This amp uses a configuration called "screen-fed self-split", in which you add a certain voltage drop on the screen grid of the tube being driven by the preamp, and the screen will work as a "second plate" with an inverted signal that can be taken from it. The .02 capacitor feeds this signal to the other 6V6, and the .01 capacitor helps prevent squealing. This is a cool configuration, because with a little work you can have almost 90% of signal going to the lower tube.
@@RobRice-so5nvit was known pretty early on, but 2 main things made it unpopular: the odd harmonic distortion from the output being imbalanced, and logistics. Why sell 1 amp with 2 output tubes when you could sell 2 amps with 1 output tube each for much more? Or make the 2-output-tube amp real fancy-like with more tubes, so people spend more for one? After all, more tubes, more better! This kind of thinking made these self-split amps fall into obscurity.
@@Bleats_Sinodai I think the point was to eliminate the phase inverter to cut the cost, and sell one amp with one less tube for less and still have practically the same output.
Thanks for filling in the blanks, BC. One of the great advantages of a public forum like TH-cam is that it gives us access to people with the expertise to answer questions that we cannot. Your explanation makes perfect sense......I appreciate it.
I am far from being anything close to expert on tube amps. It just happens that I've looked into making one on my own before, and with that I started searching in forums for projects I could mimic, and I've learned the little I know from that. I'm always glad to contribute.
This s one of the most distinctly 50’s-early 60’s sounding amps I’ve heard. Even with the TH-cam compression you can get a good feel for it. I actually REALLY like the cleans. I’m surprised it stays that clean even at noon in the dial. Very interesting output section as well.
@@UncleDoug I DO get mistaken for Russell Crowe when he was in his Gladiator period quite a lot. He asked me to show him some combat moves when he was making the film,too. I’d let him win during boxing matches to boost his confidence 🥊 😏
Another new one on me. Thank you. Concerning that power cord falling out that we've all experienced at some point. I've used velcro wraps. One or two will keep it together, they just fold over. Keeps that cord from hitting the floor and one from tripping over it. Cheers!
Uncle Doug, Greetings ! I'm a long-time voyeur, first time comment-er. First of all, thanks for your thorough and down-to-earth approach to maintaining, reconditioning, and appreciation of vintage amps. Your videos are a pleasure to watch, and I love learning new things about old amps. I have been a player, collector, and admittedly, an occasional volume abuser of amps for going on 30 years now, and I can't get enough of them ! One thing I noticed during the 1955 Magnatone Melodier video above is that you mentioned the EIA speaker code prefix of '395' being Cletron. I have several old Mother-Of-Toilet-Seat Maggies dating between 1949 and 1952 that also have speakers with the '395' prefix. I scoured and searched the internet when I first acquired them, and I found several different references that state that '395' prefix speakers were actually made by Permaflux, a Chicago speaker company that, by all accounts, was out of business by the late 1950s. They also apparently made speakers for consumer radios of the period as well. Since they were already out of business by the mid-late 1950s, most EIA code charts circulating the internet don't even mention that number now. I'm not 100% sure on this, as data is hard to come by, but since I've seen this mentioned in more than one place, I was just wondering if you were familiar with that company at all. Thanks for your time, and keep up the great work ! Best regards, Christopher (Feedback Attack)
Feedback Attack Christopher, there is all sorts of misinformation and confusion over early speakers and speaker codes. Many sites contradict each other and there is virtually no way of knowing whose right. My understanding is that the code 395 is associated with the Cletron speaker used in the 5E1 Fender Champ, which is pretty well documented. Some sites say that Permoflux is either 258 or 395 and that Cletron is 374. Here is a site discussing Permoflux speakers (which I have never heard of until now): www.magnatoneamps.com/manufacturers.html#permoflux
Eagles, the Vintage Guitar Price Guide has a value of between $550 and $650 for a nice Melodier Model 109 with dual speakers. The single-speaker version, Model 110, is $525 to $625.
Just saw this gem for the 1st time since following your channel, Doug! Interesting circuit and Sister Golden Hair to boot. Hope to see you in cyberspace again on Ewetube soon!
Hello Doug my name is Dwight behm you are a great man with a good sense of humor thank you for the way you teach things you explain things very well just wanted to say thanks I'm learning a lot from you because I love Electronics to especially in the ham radio service or Hobby whichever you want to call it been a ham radio operator for 30 years love talking to people I probably bore you to death talkin to me but you're a nice man just thank you wish I would have met you back in high school and you become my mentor I struggled too many times over the years anyway I hope you live 20 more years I'll be watching your videos all eventually see them all thanks again you were a nice man thanks for who you are not trying to be weird here but I admire your way of doing things I'll leave it at that bye for now dog God bless your friend Dwight
Hi Uncle Doug, My question is off-topic or maybe just off-subtopic. I'm a fortunate owner of this same model and year of amp. They sound great, especially for blues harmonica. The response is quick between the player's breath and the speakers' output so my harp playing friends love it. I discovered, while stressing the power cord's plug end in an awkward set up situation on stage, that the insulators of the two wires are completely rotten from end to end. Luckily no one was hurt, but the breaker for the stage tripped. I purchased a three pronged cord for it and read up on the conversion until I found a similar circuit diagram with before and after drawings. The black lead is connected to the fuse, the fuse is connected to the switch and the switch is connected to the transformer lead that used to go to the switch. The white lead is connected to the transformer lead that used to go to the fuse.I removed the death cap on spec. I tested the chassis for potential without the cap and read 2.0mV and 0.0A. I tested the chassis again with the cap alligatored in place, and the voltage was 3 times higher, still no current. I noticed the amp hums (maybe it did before but I didn't notice) and that I can reduce the hum by touching the chassis with my hand (pretty brave, am I not?). So my question is, did I mix up the black and white leads? Would it make a difference? The cord I bought has them both black, no white. I marked with painter's tape the one that should be white according to which spade it connects to, but I removed the tape prematurely while positioning componets for soldering. Thanks for giving us so much useful information. Cheers! Andrew
You may well have reversed the black and white wire. You can reverse them and see if there is a difference; however, I would think that, if the green ground wire was securely attached to the chassis and the wall receptacle offered a proper ground, that touching the chassis should make no difference. Double check the black/white connection, the security of the green (ground) lead, and the wiring of the receptacle. A properly installed 3-wire power cord and receptacle should never cause hum.....it should only reduce it.
I redid the ground wire at the amp and that solved the problem, thank you very much. I tinned the ground lead and wrapped it around the PT bolt. I redid that with a crimped on lug and that was the fix.
In my "Radiotron Designer's Handbook" page 585 the circuit is simply called "Phase inversion in the power stage" so at the time when the book was written there wasn't any name for that circuit yet.
+lucancherby Several other viewers reported specific names for the phase inversion circuit and explanations of how it functions, LC. If you read through the comments below, you will find them.
I could hear that 5Y3 right off that bat ! great sounding amp Doug. I have a Silvertone model 4721, has the 5Y3. its got personality. thanks for sharing
You're not alone. Several people liked this amp so much that they are currently building clones of it. It has a very unique phase-inverter circuit (described in video), and it has two 8" speakers.....both of which give it a very special sound.
You are so right on the money... the absence of a typical phase-inverter has robbed a little gain from the amp. It still sounds pretty solid... I wonder what would happen if we added an extra gain stage, or increased the gain of the two existing stages with cathode bypass capacitors? I wonder how the amp would sound?
I'm not sure, Mark, since I am reluctant to change the circuit in this nice, original vintage amp. Perhaps you could build one, incorporating the changes you mentioned.
Thanks for spending your time producing your videos. You have a very good voice for it. To give a little insight to how this type phase inverter works here is the explanation on it. Look at the screen grid of the top 6V6 tube. Notice it has an extra 4.7k resistor on it. In this circuit the screen grid of the top 6v6 is also acting like a plate and the extra resistor like a plate load resistor. This of course lowers the screen grid voltage on the top 6v6 tube and allows it to fluctuate with the drive signal from the 12ax7 tube giving the drive signal to the second 6v6 tube though the.02 cap which is a coupling cap. The 470K resistor on the control grid of the bottom 6V6 is simply a grid leak resistor and the .01 cap across that grid resistor is a tone cap pulling the highs off of the bottom 6v6 tube. This is a bad design lowering the output power and adding extra distortion to the signal but it does work giving it that different sound.
I thought I'd add my 2 cents - looking at the final amplifiers, one is grid driven (like most other push-pull amps), and the other one is cathode driven (what hams call 'grounded-grid'). This naturally results in opposing phases, given an identical phase input to each tube. The grounded-grid configuration is very popular for RF amplifiers because it naturally eliminates feedback from the plate circuit, since it's out of phase with the input signal, with the tradeoff of reduced gain. Tubes for this type of amplifier service are normally designed for high mu to make up for the gain loss. Although it would require a recalculation of bias, the lower 6V6 might be replaced with a 6Y6 or 6U6, which has higher mu.
An interesting analysis, Stirling. The general consensus is that the lower tube grid is driven by the screen of the upper tube, as evidenced by the .02uf coupling cap that connects them. Thanks for your input.
Doug, Your videos are much appreciated. I might have to sit down and watch ALL of them sometime. The info about Cletron speakers is helpful since I have a '54 Fender Champ. I bought it 26 years ago and never knew what sort of speaker it has. (6" Cletron!) I found an ancient Magnatone Student at a garage sale recently----the silkscreened grille cloth is in near-perfect shape. Purtiest thang you ever saw----sounds very good too. Best to you- Rick
This is so weird man... I was searching the net and came across a schematic for a 6F6 amp. For some reason, this amp's schematic came up. I sat there puzzling over that weird output section and PI... I mean, WTH!? So I google the amp to find out if anyone knows anything about it and guess whose video comes up. Geez man, is there any cool thing you don't have a hand in? :D
HEY ... I WAS WONDERING HOW LONG YOU GUYS KNEW ABOUT EACH OTHER ... I WATCH THE GUITOLOGIST AND YOU UNCLE DOUG. i GUESS US TUBE AMP JUNKIES EVENTUALLY CROSS TRACKS ... )))
Hello Uncle Doug. Many years ago I had to repair Bassman 5B6 and Champ 5F1. After repair I noticed DC voltages on tube pins and AC on power trafo. When I saw your videos about that amps I noticed that voltage values on original scheme and uploaded on my web for young tube sound fans. But, I had never repair Melodier and I don't know correct DC voltages on tubes. Have you AC and DC voltage values because I would like to put this simple excellent scheme on my web but without voltages it's very hard to control amp after some amateur made it. From my experience I know the approximate value of 12AX7 and 6V6 but whether it's a scheme with special phase inverter and I would like to know the exact values on screen grid. At least on cathode of rectifier tube. I think it must be ~ 420VDC on anode, on cathode~19VDC and~ 415VDC on 6V6 screen grid. On anode of 12AX7~110VDC and on cathode~1,6VDC. Output transformer is similary as for EL84. On one instrument channel I will, as an opportunity, to draw capacitor of 10nF in paralell 100K for bright sound. Maybe Rusty knows voltages? And of course, again and again, thanx for all your videos. Every night before sleeping I watch one your video as a memory on my youth and beautiful warm tube world. I am Croatian so sorry for my English! I hope you will understand me.
We have never owned or worked on a Magnatone amp with Vibrato, EE, but would love the opportunity. There are Internet sites that do explain the circuit, however. It's based on a component called a "varistor", which still exist, but unfortunately not in the values needed for a vibrato circuit.
Doug - I just got hip to you in 2017, but I've been interested in tube amps for thirty five years! I gotta say - for this guy's money, this Magnatone is the best sounding thing - it's got a certain something - it certainly sounds like Chuck Berry (unless it's the guitar you were using) - Love your videos - fun to watch. Tim in Seattle
Thanks, Tim, and welcome to our channel. We agree with your assessment of the mighty little Magnatone Melodier. Several other viewers were impressed enough to actually build clones of the amp. It has an unusual circuit and tone.
At that days the amp was sold new, a single 12AX7 tube worth equals nearly a workers day pay. So reducing the cost was necessary even more for let say (no fence here) second choose producers.
Hmmm..Not what I would call a "memorable amp" tonewise but your explanation of the phase inverter make sense. After WWII, people were short of money...and amazingly after 70 years of economic progress..people are still short of money.. some things never change.
SuperCarver2011 Some people loved it, and some didn't, SC. I guess it's all a matter of personal preference. I believe the unique phase inversion circuit was initially developed for radios.....probably, as you say, to reduce production cost.
More questions about the Melodier! Specifically, the cathode bypass caps on the 6V6s and the 12AX7. What voltage rating are they in the original circuit? I figure I can get away with 25V on the 12AX7, but what about on the 6V6s? 50V?
Wow, you explain these circuits in such a fashion that I'm amazed at how much I'm comprehending and retaining to memory. Grant you, as a novice I'm still far from actually building an amp, but I have more confidence in exploring the inner workings of the ones I do have. Which brings up a question about my magnatone 150: it has a multi section can cap with values of 20/450V, 20/450V, 20/50V. Is there a rule of thumb I should follow should I ever need to replace? I haven't found exact replacement for purchase online. Is it true I can use higher volt value if necessary? I have came across 20/450, 20/450, 20/450
Thanks, TP. Rusty and I are glad the videos are helpful. Yes, you can go up in voltage, but the capacitance should be within 10% (higher). The can cap you found will work just fine. The 20uf/50wv cap is a cathode bias cap, so the voltage can be higher with no problem. You can also just leave the can in place and wire in individual axial capacitors underneath the chassis.
Hi Uncle Doug, mine's finished! and I have another question. How loud is yours? At full volume, mine's bedroom level. VERY quiet. I didn't put the scope on it. My speakers are in series, total around 5 ohms. I expected it to be significantly quieter than other 6V6 push pulls, but it's nowhere near a Deluxe Reverb on 3.
@@UncleDoug that's the way they were, parallel would give a resistance of just over 1 ohm... If it was even doing 10 W it should be way louder. I'll fool with it more tomorrow. Ok, it's tomorrow, and I got it. When I put the last screw in the chassis, I caught one of the fine wires from the OT and crushed it against the chassis, grounding out the signal. When I fixed that, it got a lot louder!
The problem must reside in the circuit or the speakers themselves, Rob.....and detection of the cause will require on-site inspection. Good luck.@@RobRice-so5nv
Do you know how to get the chassis out? I just picked up one of these and don't want to break something, but i don't see what's holding it in unless it's just really wedged by the wood parts.
@@UncleDoug thanks! Found one more, hidden because of double duty on a terminal strip. Chassis still wedged, I ended up using a nylon drift with a tiny hammer as a persuader. Even after putting it back in, it doesn't want to come out.
@@UncleDoug the wood block is very tight on one side. When the chassis slides in, it wedges a little toward the back. The chassis is out, I'll get a picture. I don't know if I can post it here... maybe a link.
Perhaps your cabinet has changed shape over the years, possibly due to moisture. You can post photos on my FB page: Uncle Doug's Vintage Amps, but, to be honest, they probably would not be much help in solving the problem.@@RobRice-so5nv
Uncle Doug, I have a 1960 Magnatone custom 460 , stereo amp. But one half of the amp doesn't work. It was my dads. i got it when he passed. I've had it now for many years. Would you know any competent repair amp tech's in Saginaw,Mich.area that could fix it . It was never later worked on. My dad bought it knew in 1960. I don't know why he never got it repaired. All parts are factory as far as I know. It failed and he put it away. He then bought a Fender amp
I'm sorry to hear that, Doug. The 460 is a large, complex circuit with all sorts of possible reasons for the problem. I'm sorry, but I don't know of any techs in your area. Good luck with it.
I don't know the specs exactly, but looking at the schematic I would bet that the PT and OPT for a Fender 5E3 Deluxe would work just fine (with a little safety margin to boot). Good luck with your project :)
RiftAmps I have been looking around for the original specs on the 109 transformers as well, but it seems like the Edcor XPWR100 (www.edcorusa.com/xpwr100) would be good for the PT (and give you a couple of different options to play with as far as B+ voltages go), and the Edcor XPP25-4-7.6K (www.edcorusa.com/xpp25-4-7_6k) would make a reasonable OT. USA-made and not terribly expensive! I think the Fender 5E3 PT is a 325-0-325 B+ winding, right? This circuit is a Class-A push-pull, is it not? If so, I'd worry about cooking the 6V6s at 325*1.4.
I used a Deluxe Reverb PT (330-0-330) for my Fender Deluxe clone and ended up with a PV of 336VDC, perhaps due to the 5Y3 rectifier. The Edcor transformers do appear to be an excellent choice also. Use what you feel comfortable with.
Uncle Doug Good point, I always forget about the voltage drop with a tube rectifier (solid state rectifiers drop significantly less that can be basically ignored at B+ voltages). Perhaps a better choice would be XPWR061 (300-0-300 @ 120ma).
Just to follow up on that... I ballpark the Magnatone 109 tube complement at 100ma, and the 5Y3 data sheet shows that at 300Vac per plate will yield just shy of 325Vdc @ 100ma. So, I think I have my answer! Yay!
I do still have it, Peter, and am in the process of selling some amps to make room for more. Please contact me by private message and we can discuss it.
That amp screams “Give me a lipstick pickup and I’ll rock your world.” Interesting circuitry. I wonder if a boutique kit is available in that configuration. Sure wouldn’t be hard to change an existing kit to that.
hi uncle doug hi rusty....thank you for your very nice videos by the way you gave me the guts to dive into these tubes amps kinda things . well i have a question about the Melodier 109.. is the cathode bypass cap on 12AX7 along with 2.2k is 2uf 25v ~50v ? i tried this but it sound better with a 22uf more alive just to say. it opened that thing! on the cleans i builded that one using russians tubes 6n2p as 12ax7 and 6p6s as 6v6 very nice tubes for the price you can get vintages for a fraction of the price compare to american ones. thank you again to take the time. and happy new year cheers from montreal quebec !
+reyzn bran You're welcome, RB. We're glad you enjoy the videos :) The value of the cathode bypass cap is not legible on the schematic I have on file (and used in the video), but I would guess that it was probably 20uf@25V. Happy New Year to you from Texas, USA :)
I was just watching this video and all the talk about phase inversion got me thinking about phase shift. Do you have any videos on phase shift? If so I have missed them. I have a (heresy I know) Peavey Heritage with phase shift and I have always wondered how it works. Thanks again for the videos!!
The sound quality of this amp is exceptional. I believe it received a high number of favorable ratings on your amp comparison video from many viewers. But how does one go about finding a '55 Magnatone in this condition nowadays? Have to build one on your own is the only way.
Greetings, TF. You could file a search alert with Ebay for Magnatone Melodier and they will tell you if one comes up for auction. I may even list this one on Ebay in the near future.....I'm still undecided. The other option is to do what several viewers did, and build your own from scratch. It is an unusual circuit, with no Phase Inverter tube, but not particularly complex.
Uncle Doug This seems like a good avenue to pursue, Doug. But, why would you want to sell this rare amp? I would imagine this would only appreciate with time. I suppose I could build my own, just as you suggested.
I would love to be able to keep all of my acquisitions, TF, but limited space (and finances) sometimes forces me to "prune the tree". Also, if I don't use an amp or guitar for a while, I start thinking it might be better off in the hands of someone who would use (and appreciate) it daily. As I get older, it becomes more and more evident that you really "can't take it with you".
Would be interesting to build a clone, but with more conventional phase inversion, play it through the same speakers in the same cabinet and see what the difference is. Still way above my pay grade... I can change fuses. With supervision, obviously...
Sister golden hair First lick and the classic cocaine lick . Sweet looking amp I have an #KEIL G55 amp that i wanna get going . But keep the awesome vids coming
That's crazy how they do the phase inversion... but it works... none of the various methods to achieve phase splitting is 100% balanced... and because of this... it provides us with some sweet crossover distortion... in most cases... this method of tying the screen of one bottle to the grid of the other saves Magna $$$ due to the absence of another tube and supportive parts... How does this work? When you amplify a signal with a gain stage... you can have an inverted or non-inverted output, depending on which typology you use. Think of how we use Op-Amps? There's an invert and a non-invert wiring method; it's all the same theory. An inverted typology flips the sine-wave signal and the other mirrors it. With any pre-amp tube, you would see two wave forms, one inverted from the other flipped 180 degrees, and one that is a mirrored copy of the input, if you were to place a scope at the anode plate (inverted) and then at the cathode (non-inverted). On this Magna, the screen of one bottle is outputting an inverted signal that is 180 degrees out of phase with its input (flipped), and that inverted signal sent to the other bottle, providing the other bottle with the other side of the sine-wave. One wave up 180 degrees to one bottle and one wave down 180 degrees to the other, tied together with a common output transformer, makes a complete 360 degrees wave. The next question is... is the crossover distortion that the method that Magna uses here... pleasing or ugly as a hot place? Is it rich with the right kind of harmonics? Phase Inverter typology makes or breaks an amp if you're going to push it hard. NOTE - I guess I should explain "crossover distortion?" This is that region, that time in each full wave cycle, when the signal passes from inverted to non-inverted; and during the "crossover" of the signal from an up peak to a down peak, from one bottle to the other, there is a brief moment in time when both bottles share the signal, when both bottles are slightly on. This is crossover distortion. Does the method used here... sound pleasing or ugly when pushed?
Here is a link to a video I made with an engineer friend several years ago, before I had my own channel. He has a wonderful assortment of equipment and we were able to perform a frequency spectrum analysis on the Melodier that you may find interesting: th-cam.com/video/VufPF3OOTd0/w-d-xo.html
This amp uses a configuration called "screen-fed self-split", in which you add a certain voltage drop on the screen grid of the tube being driven by the preamp, and the screen will work as a "second plate" with an inverted signal that can be taken from it.
The .02 capacitor feeds this signal to the other 6V6, and the .01 capacitor helps prevent squealing.
This is a cool configuration, because with a little work you can have almost 90% of signal going to the lower tube.
Thanks for that info. I just gotta wonder who figured all this stuff out.
@@RobRice-so5nvit was known pretty early on, but 2 main things made it unpopular: the odd harmonic distortion from the output being imbalanced, and logistics.
Why sell 1 amp with 2 output tubes when you could sell 2 amps with 1 output tube each for much more? Or make the 2-output-tube amp real fancy-like with more tubes, so people spend more for one? After all, more tubes, more better!
This kind of thinking made these self-split amps fall into obscurity.
@@Bleats_Sinodai I think the point was to eliminate the phase inverter to cut the cost, and sell one amp with one less tube for less and still have practically the same output.
Thanks for filling in the blanks, BC. One of the great advantages of a public forum like TH-cam is that it gives us access to people with the expertise to answer questions that we cannot. Your explanation makes perfect sense......I appreciate it.
I am far from being anything close to expert on tube amps. It just happens that I've looked into making one on my own before, and with that I started searching in forums for projects I could mimic, and I've learned the little I know from that. I'm always glad to contribute.
This s one of the most distinctly 50’s-early 60’s sounding amps I’ve heard. Even with the TH-cam compression you can get a good feel for it. I actually REALLY like the cleans. I’m surprised it stays that clean even at noon in the dial. Very interesting output section as well.
Thanks for your input, Russell.
@@UncleDoug I DO get mistaken for Russell Crowe when he was in his Gladiator period quite a lot. He asked me to show him some combat moves when he was making the film,too. I’d let him win during boxing matches to boost his confidence 🥊 😏
@@williambock1821 He's a nice guy.....when he's sober.
Thanks for the kind words, TB. I really appreciate the encouragement.
Another new one on me.
Thank you.
Concerning that power cord falling out that we've all experienced at some point.
I've used velcro wraps.
One or two will keep it together, they just fold over.
Keeps that cord from hitting the floor and one from tripping over it.
Cheers!
Thanks for the tip, Amo :)
Uncle Doug,
Greetings ! I'm a long-time voyeur, first time comment-er. First of all, thanks for your thorough and down-to-earth approach to maintaining, reconditioning, and appreciation of vintage amps. Your videos are a pleasure to watch, and I love learning new things about old amps. I have been a player, collector, and admittedly, an occasional volume abuser of amps for going on 30 years now, and I can't get enough of them ! One thing I noticed during the 1955 Magnatone Melodier video above is that you mentioned the EIA speaker code prefix of '395' being Cletron. I have several old Mother-Of-Toilet-Seat Maggies dating between 1949 and 1952 that also have speakers with the '395' prefix. I scoured and searched the internet when I first acquired them, and I found several different references that state that '395' prefix speakers were actually made by Permaflux, a Chicago speaker company that, by all accounts, was out of business by the late 1950s. They also apparently made speakers for consumer radios of the period as well. Since they were already out of business by the mid-late 1950s, most EIA code charts circulating the internet don't even mention that number now. I'm not 100% sure on this, as data is hard to come by, but since I've seen this mentioned in more than one place, I was just wondering if you were familiar with that company at all.
Thanks for your time, and keep up the great work !
Best regards,
Christopher (Feedback Attack)
Feedback Attack Christopher, there is all sorts of misinformation and confusion over early speakers and speaker codes. Many sites contradict each other and there is virtually no way of knowing whose right. My understanding is that the code 395 is associated with the Cletron speaker used in the 5E1 Fender Champ, which is pretty well documented. Some sites say that Permoflux is either 258 or 395 and that Cletron is 374. Here is a site discussing Permoflux speakers (which I have never heard of until now): www.magnatoneamps.com/manufacturers.html#permoflux
Eagles, the Vintage Guitar Price Guide has a value of between $550 and $650 for a nice Melodier Model 109 with dual speakers. The single-speaker version, Model 110, is $525 to $625.
Unique phase inversion , ive never imagined that trick wow !
The signal gain may be losing power using that PI trick !
I'm not so sure, Ijams. The amp has excellent power and volume.
Just saw this gem for the 1st time since following your channel, Doug!
Interesting circuit and Sister Golden Hair to boot.
Hope to see you in cyberspace again on Ewetube soon!
Thanks so much, Vinny. Glad you liked it :)
Great stuff! One of these just came into the shop with parasitic oscillation at high volume... This review helps me get started!
We're glad it was helpful, Sawyer :)
My amp has the same problem when I use the preamp tube. But don't when I use the input going to volume pot. I'm at a loss
Great vid, as usual Uncle Doug. Got a fellow bringing me one of these for repair tomorrow - can't wait! Thanks, and big ups, as they say.
Thanks, Shaun. Good luck with it :)
Nice little vid, Doug. Thank you.
One upside to this circuit is the output tubes would probably last forever.
You're welcome, GM. Let's hope so :)
Got the amp fixed. Two new speakers. Sounds great. 🇨🇦
That's good to hear, Scott. Congratulations on a successful repair.
Hello Doug my name is Dwight behm you are a great man with a good sense of humor thank you for the way you teach things you explain things very well just wanted to say thanks I'm learning a lot from you because I love Electronics to especially in the ham radio service or Hobby whichever you want to call it been a ham radio operator for 30 years love talking to people I probably bore you to death talkin to me but you're a nice man just thank you wish I would have met you back in high school and you become my mentor I struggled too many times over the years anyway I hope you live 20 more years I'll be watching your videos all eventually see them all thanks again you were a nice man thanks for who you are not trying to be weird here but I admire your way of doing things I'll leave it at that bye for now dog God bless your friend Dwight
Wow, thanks so much, Dwight. It's great to hear from you.
Hi Uncle Doug,
My question is off-topic or maybe just off-subtopic. I'm a fortunate owner of this same model and year of amp. They sound great, especially for blues harmonica. The response is quick between the player's breath and the speakers' output so my harp playing friends love it. I discovered, while stressing the power cord's plug end in an awkward set up situation on stage, that the insulators of the two wires are completely rotten from end to end. Luckily no one was hurt, but the breaker for the stage tripped. I purchased a three pronged cord for it and read up on the conversion until I found a similar circuit diagram with before and after drawings. The black lead is connected to the fuse, the fuse is connected to the switch and the switch is connected to the transformer lead that used to go to the switch. The white lead is connected to the transformer lead that used to go to the fuse.I removed the death cap on spec. I tested the chassis for potential without the cap and read 2.0mV and 0.0A. I tested the chassis again with the cap alligatored in place, and the voltage was 3 times higher, still no current. I noticed the amp hums (maybe it did before but I didn't notice) and that I can reduce the hum by touching the chassis with my hand (pretty brave, am I not?).
So my question is, did I mix up the black and white leads? Would it make a difference? The cord I bought has them both black, no white. I marked with painter's tape the one that should be white according to which spade it connects to, but I removed the tape prematurely while positioning componets for soldering.
Thanks for giving us so much useful information.
Cheers!
Andrew
You may well have reversed the black and white wire. You can reverse them and see if there is a difference; however, I would think that, if the green ground wire was securely attached to the chassis and the wall receptacle offered a proper ground, that touching the chassis should make no difference. Double check the black/white connection, the security of the green (ground) lead, and the wiring of the receptacle. A properly installed 3-wire power cord and receptacle should never cause hum.....it should only reduce it.
I redid the ground wire at the amp and that solved the problem, thank you very much. I tinned the ground lead and wrapped it around the PT bolt. I redid that with a crimped on lug and that was the fix.
1:42 it's these moments that make me hooked to Uncle Doug's videos
We're glad you enjoy them, Dj.
Very good Demo.
Great vintage sound.
Thank you for these videos.
Travis in Ky.
In my "Radiotron Designer's Handbook" page 585 the circuit is simply called "Phase inversion in the power stage" so at the time when the book was written there wasn't any name for that circuit yet.
+lucancherby Several other viewers reported specific names for the phase inversion circuit and explanations of how it functions, LC. If you read through the comments below, you will find them.
I could hear that 5Y3 right off that bat ! great sounding amp Doug. I have a Silvertone model 4721, has the 5Y3. its got personality. thanks for sharing
+chuck jones You're welcome, Chuck.....glad you enjoyed it :)
Man I’m too late to this. Just restored an identical one. Love amp to work on!
Yes, indeed, LV :)
I really like these old Magnatones.
You're not alone. Several people liked this amp so much that they are currently building clones of it. It has a very unique phase-inverter circuit (described in video), and it has two 8" speakers.....both of which give it a very special sound.
Another great sounding amp.
Thanks, Clarence.
I'm not sure, Barry. I tend to only use it with a clean input signal.
You are so right on the money... the absence of a typical phase-inverter has robbed a little gain from the amp. It still sounds pretty solid... I wonder what would happen if we added an extra gain stage, or increased the gain of the two existing stages with cathode bypass capacitors? I wonder how the amp would sound?
I'm not sure, Mark, since I am reluctant to change the circuit in this nice, original vintage amp. Perhaps you could build one, incorporating the changes you mentioned.
I will try that. I have enough parts to do it and a great scope. I'll deadbug one up...
Good luck and be sure to share your findings with us.
Wha Happen?
Thanks for spending your time producing your videos. You have a very good voice for it. To give a little insight to how this type phase inverter works here is the explanation on it. Look at the screen grid of the top 6V6 tube. Notice it has an extra 4.7k resistor on it. In this circuit the screen grid of the top 6v6 is also acting like a plate and the extra resistor like a plate load resistor. This of course lowers the screen grid voltage on the top 6v6 tube and allows it to fluctuate with the drive signal from the 12ax7 tube giving the drive signal to the second 6v6 tube though the.02 cap which is a coupling cap. The 470K resistor on the control grid of the bottom 6V6 is simply a grid leak resistor and the .01 cap across that grid resistor is a tone cap pulling the highs off of the bottom 6v6 tube. This is a bad design lowering the output power and adding extra distortion to the signal but it does work giving it that different sound.
You're welcome, ND, and thanks for your excellent explanation of the Melodier phase inverter. We appreciate your informative input.
I thought I'd add my 2 cents - looking at the final amplifiers, one is grid driven (like most other push-pull amps), and the other one is cathode driven (what hams call 'grounded-grid'). This naturally results in opposing phases, given an identical phase input to each tube. The grounded-grid configuration is very popular for RF amplifiers because it naturally eliminates feedback from the plate circuit, since it's out of phase with the input signal, with the tradeoff of reduced gain. Tubes for this type of amplifier service are normally designed for high mu to make up for the gain loss. Although it would require a recalculation of bias, the lower 6V6 might be replaced with a 6Y6 or 6U6, which has higher mu.
An interesting analysis, Stirling. The general consensus is that the lower tube grid is driven by the screen of the upper tube, as evidenced by the .02uf coupling cap that connects them. Thanks for your input.
@@UncleDoug Good stuff, and good to hear from you sir - hope all is well, and Merry Christmas!
@@stirlingschmidt6325 Likewise, Stirling :)
Doug,
Your videos are much appreciated. I might have to sit down and watch ALL of them sometime.
The info about Cletron speakers is helpful since I have a '54 Fender Champ. I bought it 26 years ago and never knew what sort of speaker it has. (6" Cletron!)
I found an ancient Magnatone Student at a garage sale recently----the silkscreened grille cloth is in near-perfect shape. Purtiest thang you ever saw----sounds very good too.
Best to you-
Rick
Greetings, Rick, and thanks for the very kind words. It's great to hear that the videos are helpful. Best wishes to you and yours :)
This is so weird man... I was searching the net and came across a schematic for a 6F6 amp. For some reason, this amp's schematic came up. I sat there puzzling over that weird output section and PI... I mean, WTH!? So I google the amp to find out if anyone knows anything about it and guess whose video comes up. Geez man, is there any cool thing you don't have a hand in? :D
HEY ... I WAS WONDERING HOW LONG YOU GUYS KNEW ABOUT EACH OTHER ... I WATCH THE GUITOLOGIST AND YOU UNCLE DOUG. i GUESS US TUBE AMP JUNKIES EVENTUALLY CROSS TRACKS ... )))
Hello Uncle Doug. Many years ago I had to repair Bassman 5B6 and Champ 5F1. After repair I noticed DC voltages on tube pins and AC on power trafo. When I saw your videos about that amps I noticed that voltage values on original scheme and uploaded on my web for young tube sound fans. But, I had never repair Melodier and I don't know correct DC voltages on tubes. Have you AC and DC voltage values because I would like to put this simple excellent scheme on my web but without voltages it's very hard to control amp after some amateur made it. From my experience I know the approximate value of 12AX7 and 6V6 but whether it's a scheme with special phase inverter and I would like to know the exact values on screen grid. At least on cathode of rectifier tube. I think it must be ~ 420VDC on anode, on cathode~19VDC and~ 415VDC on 6V6 screen grid. On anode of 12AX7~110VDC and on cathode~1,6VDC. Output transformer is similary as for EL84. On one instrument channel I will, as an opportunity, to draw capacitor of 10nF in paralell 100K for bright sound. Maybe Rusty knows voltages? And of course, again and again, thanx for all your videos. Every night before sleeping I watch one your video as a memory on my youth and beautiful warm tube world. I am Croatian so sorry for my English! I hope you will understand me.
Hoping for some new videos soon. I am really wanting to see a video explaining the workings of the VIBRATO function in Magnatone Amps some day.
We have never owned or worked on a Magnatone amp with Vibrato, EE, but would love the opportunity. There are Internet sites that do explain the circuit, however. It's based on a component called a "varistor", which still exist, but unfortunately not in the values needed for a vibrato circuit.
Doug - I just got hip to you in 2017, but I've been interested in tube amps for thirty five years! I gotta say - for this guy's money, this Magnatone is the best sounding thing - it's got a certain something - it certainly sounds like Chuck Berry (unless it's the guitar you were using) - Love your videos - fun to watch. Tim in Seattle
Thanks, Tim, and welcome to our channel. We agree with your assessment of the mighty little Magnatone Melodier. Several other viewers were impressed enough to actually build clones of the amp. It has an unusual circuit and tone.
Just picked one up an an estate sale $40. Gonna need some work. Someone has put a 3 prong plug on it. I like watching your videos. 🇨🇦
That was a major score, Scott. They tend to cost a whole lot more in amp stores :)
i definately like you demo influences great stuff and this amp is out of the ordinary ,sounded good though
Thanks, Joe.
Magnatone lifted the circuit from Philco radio. Interesting that they promoted as their new circuit.
At that days the amp was sold new, a single 12AX7 tube worth equals nearly a workers day pay. So reducing the cost was necessary even more for let say (no fence here) second choose producers.
Just stumbled onto your channel. It's great!
+Hillbilly Hellcats Thanks so much, HH. Welcome aboard :)
Hmmm..Not what I would call a "memorable amp" tonewise but your explanation of the phase inverter make sense. After WWII, people were short of money...and amazingly after 70 years of economic progress..people are still short of money..
some things never change.
SuperCarver2011 Some people loved it, and some didn't, SC. I guess it's all a matter of personal preference. I believe the unique phase inversion circuit was initially developed for radios.....probably, as you say, to reduce production cost.
hi, I have the same year amp and in very similar condition...love it... what would the value $ be on one of these amps....curious.
More questions about the Melodier! Specifically, the cathode bypass caps on the 6V6s and the 12AX7. What voltage rating are they in the original circuit? I figure I can get away with 25V on the 12AX7, but what about on the 6V6s? 50V?
Jason Thorpe That sounds reasonable. You could go with 100V (for a few cents more) and be really safe.
Since it is out of focus do you think that maybe the handle was made from "Big Foot" hide?
Yes. Since it's impossible to focus on Big Foot.....or his hide.
Wow, you explain these circuits in such a fashion that I'm amazed at how much I'm comprehending and retaining to memory. Grant you, as a novice I'm still far from actually building an amp, but I have more confidence in exploring the inner workings of the ones I do have. Which brings up a question about my magnatone 150: it has a multi section can cap with values of 20/450V, 20/450V, 20/50V. Is there a rule of thumb I should follow should I ever need to replace? I haven't found exact replacement for purchase online. Is it true I can use higher volt value if necessary? I have came across 20/450, 20/450, 20/450
Thanks, TP. Rusty and I are glad the videos are helpful. Yes, you can go up in voltage, but the capacitance should be within 10% (higher). The can cap you found will work just fine. The 20uf/50wv cap is a cathode bias cap, so the voltage can be higher with no problem. You can also just leave the can in place and wire in individual axial capacitors underneath the chassis.
Hi Uncle Doug, mine's finished! and I have another question. How loud is yours? At full volume, mine's bedroom level. VERY quiet. I didn't put the scope on it. My speakers are in series, total around 5 ohms. I expected it to be significantly quieter than other 6V6 push pulls, but it's nowhere near a Deluxe Reverb on 3.
Why are your speakers in series? Have you tried them in parallel?
@@UncleDoug that's the way they were, parallel would give a resistance of just over 1 ohm... If it was even doing 10 W it should be way louder. I'll fool with it more tomorrow. Ok, it's tomorrow, and I got it. When I put the last screw in the chassis, I caught one of the fine wires from the OT and crushed it against the chassis, grounding out the signal. When I fixed that, it got a lot louder!
The problem must reside in the circuit or the speakers themselves, Rob.....and detection of the cause will require on-site inspection. Good luck.@@RobRice-so5nv
Thanks @@UncleDoug I got it. See edit above, OT wire was pinched to the chassis. It sounds fantastic, really great tone and breakup.
Problems like this are rarely, if ever, solvable long distance. I'm glad you located and resolved the problem. @@RobRice-so5nv
Well that's different... but different in a cool way
Yes, indeed :)
Do you know how to get the chassis out? I just picked up one of these and don't want to break something, but i don't see what's holding it in unless it's just really wedged by the wood parts.
Look for some screws through the sheet metal into the wood.
@@UncleDoug thanks! Found one more, hidden because of double duty on a terminal strip. Chassis still wedged, I ended up using a nylon drift with a tiny hammer as a persuader. Even after putting it back in, it doesn't want to come out.
Very strange, Rob. I don't recall having any trouble at all removing the chassis in my amp.@@RobRice-so5nv
@@UncleDoug the wood block is very tight on one side. When the chassis slides in, it wedges a little toward the back. The chassis is out, I'll get a picture. I don't know if I can post it here... maybe a link.
Perhaps your cabinet has changed shape over the years, possibly due to moisture. You can post photos on my FB page: Uncle Doug's Vintage Amps, but, to be honest, they probably would not be much help in solving the problem.@@RobRice-so5nv
how does it sound with some distorted guitar?
Wonders why you did not show us the physical circuitry.
So do I, Tim. I usually do show the circuitry.
Uncle Doug, I have a 1960 Magnatone custom 460 , stereo amp. But one half of the amp doesn't work. It was my dads. i got it when he passed. I've had it now for many years. Would you know any competent repair amp tech's in Saginaw,Mich.area that could fix it . It was never later worked on. My dad bought it knew in 1960. I don't know why he never got it repaired. All parts are factory as far as I know. It failed and he put it away. He then bought a Fender amp
I'm sorry to hear that, Doug. The 460 is a large, complex circuit with all sorts of possible reasons for the problem. I'm sorry, but I don't know of any techs in your area. Good luck with it.
thank you very informative
You're welcome, AA. Glad you liked it :)
Hi Doug,
Do you happen to know the TX specs for the Magnatone 109? Such an unusual design I must build one!
Thanks
Chris
I don't know the specs exactly, but looking at the schematic I would bet that the PT and OPT for a Fender 5E3 Deluxe would work just fine (with a little safety margin to boot). Good luck with your project :)
RiftAmps I have been looking around for the original specs on the 109 transformers as well, but it seems like the Edcor XPWR100 (www.edcorusa.com/xpwr100) would be good for the PT (and give you a couple of different options to play with as far as B+ voltages go), and the Edcor XPP25-4-7.6K (www.edcorusa.com/xpp25-4-7_6k) would make a reasonable OT. USA-made and not terribly expensive!
I think the Fender 5E3 PT is a 325-0-325 B+ winding, right? This circuit is a Class-A push-pull, is it not? If so, I'd worry about cooking the 6V6s at 325*1.4.
I used a Deluxe Reverb PT (330-0-330) for my Fender Deluxe clone and ended up with a PV of 336VDC, perhaps due to the 5Y3 rectifier. The Edcor transformers do appear to be an excellent choice also. Use what you feel comfortable with.
Uncle Doug Good point, I always forget about the voltage drop with a tube rectifier (solid state rectifiers drop significantly less that can be basically ignored at B+ voltages). Perhaps a better choice would be XPWR061 (300-0-300 @ 120ma).
Just to follow up on that... I ballpark the Magnatone 109 tube complement at 100ma, and the 5Y3 data sheet shows that at 300Vac per plate will yield just shy of 325Vdc @ 100ma. So, I think I have my answer! Yay!
Did i hear a little (sister golden hair) in that demo?
Yes, indeed, Mike. It's good to know that one of my (mediocre) musical interpretations is actually identifiable. Thanks !! :))
Doug do you still have this amp for sale?
I do still have it, Peter, and am in the process of selling some amps to make room for more. Please contact me by private message and we can discuss it.
That amp screams “Give me a lipstick pickup and I’ll rock your world.”
Interesting circuitry. I wonder if a boutique kit is available in that configuration. Sure wouldn’t be hard to change an existing kit to that.
After I posted this video, several viewers built the circuit at home, with excellent results.
hi uncle doug hi rusty....thank you for your very nice videos by the way you gave me the guts to dive into these tubes amps kinda things .
well i have a question about the Melodier 109.. is the cathode bypass cap on 12AX7 along with 2.2k is 2uf 25v ~50v ?
i tried this but it sound better with a 22uf more alive just to say. it opened that thing! on the cleans
i builded that one using russians tubes 6n2p as 12ax7 and 6p6s as 6v6 very nice tubes for the price you can get vintages for a fraction of the price compare to american ones. thank you again to take the time. and happy new year cheers from montreal quebec !
+reyzn bran You're welcome, RB. We're glad you enjoy the videos :) The value of the cathode bypass cap is not legible on the schematic I have on file (and used in the video), but I would guess that it was probably 20uf@25V. Happy New Year to you from Texas, USA :)
I was just watching this video and all the talk about phase inversion got me thinking about phase shift. Do you have any videos on phase shift? If so I have missed them. I have a (heresy I know) Peavey Heritage with phase shift and I have always wondered how it works. Thanks again for the videos!!
You're welcome, Jack. Watch the videos on Tremolo circuits for a detailed explanation of phase shift.
Oh okay, I will thanks!!
The sound quality of this amp is exceptional. I believe it received a high number of favorable ratings on your amp comparison video from many viewers. But how does one go about finding a '55 Magnatone in this condition nowadays? Have to build one on your own is the only way.
Greetings, TF. You could file a search alert with Ebay for Magnatone Melodier and they will tell you if one comes up for auction. I may even list this one on Ebay in the near future.....I'm still undecided. The other option is to do what several viewers did, and build your own from scratch. It is an unusual circuit, with no Phase Inverter tube, but not particularly complex.
Uncle Doug
This seems like a good avenue to pursue, Doug. But, why would you want to sell this rare amp? I would imagine this would only appreciate with time. I suppose I could build my own, just as you suggested.
I would love to be able to keep all of my acquisitions, TF, but limited space (and finances) sometimes forces me to "prune the tree". Also, if I don't use an amp or guitar for a while, I start thinking it might be better off in the hands of someone who would use (and appreciate) it daily. As I get older, it becomes more and more evident that you really "can't take it with you".
Uncle Doug
You can say that again, Doug. I've realized the same thing as I've aged.
Hey Doug, I don't suppose you could convince Rusty to measure the outside dimensions of your Melodier? :-)
Jason Thorpe Rusty says it's about 17" wide by 13" tall by 6" front-to-back at the top and 9" ftb at the bottom.
Would be interesting to build a clone, but with more conventional phase inversion, play it through the same speakers in the same cabinet and see what the difference is. Still way above my pay grade... I can change fuses. With supervision, obviously...
You might surprise yourself, Bill. Give it a try.....carefully, of course.
Sister golden hair First lick and the classic cocaine lick . Sweet looking amp I have an #KEIL G55 amp that i wanna get going . But keep the awesome vids coming
Right you are. Thanks, Adam. We will :)
That's crazy how they do the phase inversion... but it works... none of the various methods to achieve phase splitting is 100% balanced... and because of this... it provides us with some sweet crossover distortion... in most cases... this method of tying the screen of one bottle to the grid of the other saves Magna $$$ due to the absence of another tube and supportive parts... How does this work? When you amplify a signal with a gain stage... you can have an inverted or non-inverted output, depending on which typology you use. Think of how we use Op-Amps? There's an invert and a non-invert wiring method; it's all the same theory. An inverted typology flips the sine-wave signal and the other mirrors it. With any pre-amp tube, you would see two wave forms, one inverted from the other flipped 180 degrees, and one that is a mirrored copy of the input, if you were to place a scope at the anode plate (inverted) and then at the cathode (non-inverted). On this Magna, the screen of one bottle is outputting an inverted signal that is 180 degrees out of phase with its input (flipped), and that inverted signal sent to the other bottle, providing the other bottle with the other side of the sine-wave. One wave up 180 degrees to one bottle and one wave down 180 degrees to the other, tied together with a common output transformer, makes a complete 360 degrees wave. The next question is... is the crossover distortion that the method that Magna uses here... pleasing or ugly as a hot place? Is it rich with the right kind of harmonics? Phase Inverter typology makes or breaks an amp if you're going to push it hard. NOTE - I guess I should explain "crossover distortion?" This is that region, that time in each full wave cycle, when the signal passes from inverted to non-inverted; and during the "crossover" of the signal from an up peak to a down peak, from one bottle to the other, there is a brief moment in time when both bottles share the signal, when both bottles are slightly on. This is crossover distortion. Does the method used here... sound pleasing or ugly when pushed?
Here is a link to a video I made with an engineer friend several years ago, before I had my own channel. He has a wonderful assortment of equipment and we were able to perform a frequency spectrum analysis on the Melodier that you may find interesting: th-cam.com/video/VufPF3OOTd0/w-d-xo.html
Wow... Thanks... I'll check that out!
i love this amp. i made from a random hifi amp
Thanks for sharing, Cody.
Funny how cost efficiency in the 50s leads to tonality for studio musicians today Danelectro is another example
That's an excellent point, Bob. Thanks !!
Uncly Doug the 3rd chord is a ghost or even missed out on Cocaine
Thanks, H-1
Little Cocaine in the too🎸
Yep.....but only in the video ;)