0.0047uF (microfarad), 4.7nF (nanofarad) and 4700pF (picofarad) are all the same thing if anyone is getting confused. It might actually help you find a certain brand/type if you want to purchase one for your amp. I like Class 2 Z5U dielectric 1000vdc ceramic capacitors as bright caps in Fender and Marshall amps. Polystyrene and silver mica caps are also popular choices. 500vdc or higher is a good safety margin for AC service, even though bright caps in this position will never see anything over 100vac.
I have a toggle switch on my Ceriatone KK (essentially a Marshall circuit). I'm thinking of going with a 500pf, and a 100pf. I'm on the fence regarding dielectric type. I also have 500pf Sprague polyester caps. People rarely talk about these. I've been considering a ceramic in the tone stack, so I don't want too many of them in the circuit. What do you think?
@@qua7771 That's a big jump in upper mid frequincies. Also the stock value in JCM800's and 2203/4 Lead JMP's to the master volume. As to answer the previous question, I like ceramic caps in some circuits. Stuff like Valco, Silvertone, Gretsch, Gibson, Magnatone and some Fender amps used a lot of them in the small to mid sized amps. Ceramic caps are microphonic though. You don't want them in a high powered combo amp in every position.
I am still a bit confused about the values. Pete demonstrates that going from 4700 pf down to 600pf makes it more harsh. So the lower the value = more bright/thin. Then he demonstrates the lowest value at 100pf and thats the most usable through out the range. How does that makes sense? Am I understanding the values correctly: 4700pf>600pf>100pf?
I didn’t understand bright caps until I purchased the Marshall SV20. The bright cap was so aggressive and harsh that the amp, to me, was unplayable. I had the cap removed and then later purchased a 1987x and had that bright cap removed. Much better in both instances for me.
WARNING! Valve amps have huge power capacitors that hold a lot of volts (600+). If you touch them when they are charged they will discharge through you and probably kill you! Unless you learn how to use a discharge tool (easily made) and a multimeter to check it worked don't mess inside your amp. Although Pete mentions briefly at the end I don't think it was stressed enough the potential danger involved in opening your amp. I built my own amp (Fender 5e3) so not saying you can't do this but look up discharge tools and how to use them. Also keep 1 hand in your pocket whilst you are using it so you can't accidentally discharge across your chest.
My advice is to use the motherload of heat shrink in the more dangerous areas, I saw a guy building a jtm45(?) And was like "wow, How have I never thought about this?" and to obviously do the one hand trick.
Contents: With SL-68: Introduction 0:00 - 5:22 4700pF Bright Cap Jumpered: 5:23 - 6:12 4700pF Bright Cap Not jumpered: 6:13 - 6:30 4700pF Bright Cap Back jumpered, blending in Volume 2: 6:31 - 6:57 No Bright Cap Not Jumpered Adjusting Presence and Treble: 7:04 - 8:08 4700pF Bright Cap Not Jumpered Turning up Volume 1: 8:09 - 9:26 680pF Bright Cap Turning Up Volume 1 Not Jumpered: 9:27 - 10:07 680pF and 4700 pF Bright Cap Comparison Not Jumpered: 10:08 - 11:22 4700pF Jumpered - Adjusting Volume 1 and 2: 11:23 - 12:58 No Bright Cap Adjusting Presence and Treble: 12:59 - 14:44 4700pF Bright Cap Back, tightenting up gain: 14:45 - 15:19 With 1972 50W Marshall JMP: 100pF Bright Cap Not Jumpered: 15:20 - 17:12 100pF Bright Cap Jumpered: 17:13 - 17:58 100pF Bright Cap Not Jumpered: 17:59 - 18:17 Ending and Pete’s Preferences: 18:18 - 19:37
Tried this mod on my JTM45 for about a week and then had my tech take it back off. Just kills the warmth of the tone IMO. I kept preferring the sound when you had it turned off and the treble and presence pushed a bit more. That sound is what makes those amps incredible to me. All good tho, still learned something.
Great video! I am a huge fan of the bright cap! I know lots of people who remove it on Marshalls… but that’s like a HUGE part of the Marshall sound and a big no-no for me. I just finished a build a few months ago centered on a 1987 (utilizing original 60’s/70’s parts, Piher resistors, Mullard caps etc), but instead of having the “normal” channel, I added a switch to route the bright channel into v1b, so it switches into a 2204 (even switches a master volume in/out). But for this amp I wanted more control on the bright cap - it can get a bit raunchy (depending on the value) when you start dialing the gain back, so I came up with a unique (at least unique to me) mod for this… As per usual, I connected that output of stage 1 to the GAIN (1MΩ) pot input, then from there I connected my 1000pF cap to an input of another (dedicated) 1MΩ pot. Then the output of that additional pot gets wired back to the GAIN pot’s output (middle lug). So it’s like having a bright cap in it’s usual place (between the input and output lugs) with a variable resistor in series with the cap to allow me to control the amount of bright cap that is passing to stage 2. Sort of a blend knob I suppose? It’s great for when I want to dial the GAIN knob back to 5, I pull that additional pot (“tone” pot) down to 5 or 6 so it still has that bright Marshall sound, just a bit more useable in my opinion.
Really interesting and well demonstrated (as always) vid, Pete. Thanks for taking the time to do this. I’ve been in two minds about getting into this with my 1987x which I currently use with no bright cap but have the 4700uf on a push pull. I think I’ll just leave it alone now having heard a real world comparison. Rock on!
You can stack caps in parallel too, and if you are super lucky you can find a concentric pot and rotary switch so you could stack from no bright cap to 2,3,4 or 5 different values. You can make a lot of sweet spots that way.
I removed the 470pf and dropped a 4700pf on my Plexi clone, there is a HUGE difference even at low volumes. i felt the 4700pf provided all the frequencies even at low volumes, compare to all-treble that the 470pf provide….even the 1000pf sounds shrilly to my ears..
I had a PC board JCM 800 and it didn't sound great... Using my electronics and electrical background knowledge, I tore it apart and built a point to point wired JCM 800 along with custom wound mercury magnetics transformers... What an amazing difference!!! Then I played with caps and pots and installed a cap switch knob for exactly this reason. That exact amp went to Germany with "Jim" whatever his name was (Opening act for Anthrax in Germany that year) and Scott Ian asked if I could make a 100W version.. hence I began building 6-50W and 6-100W "Marshall" amps and experimenting with the 'Plexi" circuit which was good but... a little tweaking and WHOA!! it breathed FIRE!!! Anywhoo, cool video that brought back some memories of tweaking amps with just different pots and caps! Cheers dude! (1st 50W amp took 40 hours to build and another 40 hours to tweak on the scope!)
Great video as always! The way I approach it is using the cap to decide the cutoff frequency, as you clearly explained, and using an optional resistor is series to attenuate the signal going through the bright cap, therefore defining the sweet spot of the Volume I. That way, for example, a 500pF cap can sound balanced when Volume I is at lower settings.
8:00 ? why on earth would you want to change that???? That is classic Marshall 100%. Full on in your face chunky distorted growly with just enough bite.
When you have no bright cap and turn the amp volume down so that it is clean there is a treble roll off due to the capacitance in the tubes, lots of people like this treble roll off. Using 90-100pf bright cap keeps the top end more level through out the range of the volume control. That is why that value was chosen and used by many since. Adding 680 - 1000 - 4700uf makes the volume control a tone control.
The original idea was to retain some brightness as the level was rolled off. Fender maybe had a better approach with their tapped pots. They used them multiple times in varying tap percentages & tapers. There is the brown & blonde hi fi tone stacks and the 90% treble bleed cap on their 1970s master volumes, but no all of their master volume amps got that pot. The Bassman amps never got it. The volume is always a bit of a tone control and it varies with the impedance of your guitar output or whatever is last in you effects or pedal board signal chain. Sometimes a just clean buffer is a good idea. It sort of equalizes everything out so a Strat & Les Paul can show the amp's input the same impedance.
My understanding, the reason you like the no bright cap and presence sound best at 13:30 is because the presence cuts the fizz and ice picks at the power tube stage leaving behind the good stuff, the bright cap and treble pot cut at the early preamp stages which cuts out and doesn't allow the upper harmonics to develop, the presence control cuts all the fizz and ice picks at the last power tube stage and leaves all that beauty harmonic distortion behind for you to enjoy
Very cool demonstration, Pete. I'm glad that you like and played "stone in love". The song is simple but brilliant and the reason I picked up the guitar. Neal is a ferocious guitar player when he wants to be and it shines through in this song. The solo is to me, still the epitome of what a great "song within a song" solo should be along with a monstrous guitar tone :) kudos my friend
When I build amps, and voice them at the end, I spend the most time with the treble cap on the volume and mixing resistors bright caps. They get the excitement in the sound, but must be voiced for the volume you expect to play at, which is difficult. That’s why I have often put three way switches in for my amps for the caps.
I love all the tones on my stock 71 1987 from about 3-7 on the bright volume, straight into the top left input no patching. On the lower settings just use the guitar tone controls to tame the high end. Helps that I’m running through a 68 straight cab with Pulsonic Greenbacks as they are nice and warm. Modern speakers or even Blackbacks make it much harder to use these amps this way. The only time I’d ever jump channels is if I wanted a clean pedal platform….. and who buys a classic Marshall for that !!
EE chiming in here.... One way to view this cap in parallel with the pot is that it is a frequency dependent resistor. The capacitor "resistance" is known as the reactance. The formula is Xc= 1/ (2 * pi * Freq * C). where pi is 3.14, Freq in Hz, C in uF (1e10-6) or pF (1e10-12). The result is in ohms. Another thing to remember when placing resistors in parallel is the combined resistance is always lower than the lowest resistor value. So if the bright cap resistance is getting lower then it dominates the signal path and routes the higher frequencies around the pot. Lastly, if possible use a metal film capacitor type vs. a cheap ceramic as the bright cap or (bleed cap in the guitar). There are technical reasons for this but in the end they sonically sound better.
I experimented with this a while back and tried something I haven't seen anyone else describe. I left the original cap in place and added a potentiometer to control how much signal was getting to the cap (I think I placed it in series but I don't remember for certain; but parallel should as well). So I was getting the same frequency cutoff but could control the signal level. I found this to be so effective and satisfying (and especially useful at different volume levels) that I considered for while installing the pot permanently in the amp. (Maybe replace Presence with a concentric pot (two pots in one) to avoiding drilling?) I remember thinking that it was actually more effective than the Presence control.
Your Marshall sounds like mine. It's my 3rd since I got my first in London in '71 when of all guys Ron Wood was using one and put me onto one he seen from a studio I could get relatively cheap. At 75 I hope this one sees me out, LOL.
Fantastic video. It is helping me get familiar with a new amp that also has a switch that allows you to choose between three bright cap settings--one of which is no bright cap. Super helpful examples/tones--thank you!
With a Fender if I don’t clip, I just turn the amp to 6.5 and put a passive volume pedal at the end or before the delays and such. It’s bypassed but I’m sending my levels in so it’s clean or break up at full throttle. I also makes sure I have a buffer pedal in the chain before. I like a set and leave it approach, but the mods are cool as well, just to get rid of it at lower gains. But there’s a lot of ways to use or get around it. As long as I don’t have to gain stage every time I move my amp all my pedals and amp settings…I’m good!
Also that bright channel coupling cap makes a difference.. many of the marshalls used .0022 for the treble channel where others used the .022. I never liked the .0022..they just seemed way to bright and harsh.. but depends on other factors too. Others might love it..
Mine has a .022uf cap, and the bass is way out of control. With a coupling cap that large there is sound being produced below hearing range, and the speakers capability. The only way I could see it being tolerable is if the power amp has very small coupling caps. If so that would explain why the .0022uf channel sounds thin.
Great vid. I think a lot of people don’t have a good understanding of this subject thinking a lower value bright cap will have less treble when a higher value will actually sound better because it lets more high mids through. I just changed my 470 p. to 1nF in my Ceriatone 2204 and now it sounds like a Marshall.
Great video! You explained the bright cap in a very easy to understand way and then did a superb job demoing it. Thanks again, these videos are fantastic. 👍🏼
Years ago I lifted one leg of the bright cap in my 77 JMP and it completely transformed the amp for the best. The other leg is still soldered on, so if I sold it and the buyer wanted the cap in, you just bend it back into place and solder it back in place.
Tried clipping in a 4700 pf. I use the SL68 mainly as a pedal platform. I am more used to Friedman, JVM, XTC distortion so I use pedals on the SL68 for distortion. The 4700 sounded cool without pedals. Definitely need to roll off treble, presence and blend in channel 2. But with pedals it was pretty harsh. I’ll use a push pull if I keep it in. Great video. Thanks.
Awesome Pete! I've recently discovered the whole "cap" tone differences in both guitars and amps over the last few years. Makes such a HUGE difference! Your tones here are KILLER! ON A SIDE NOTE: I actually started shooting my video to showcase my old amp that Neal Schon endorsed in the early 90's & you and I played the same Journey and Zep tunes! Oh and I have my black Les Paul! Haha! I think I'll reshoot my opening.
Hey Arthur, seen U on chat with Pete, U have good advice on putting caps and resistors in the guitar or maybe to upgrade pedal or none tube Amp combos like Peavey's or Roland, Fender?? Just throw it your way and leave link would be Kool 2 C what u do and all, seen Ben Coombs show, and always like seeing others, TY, good 2 meet through Pete, he's got the right stuff,
@@Ryan-Hall Hey! Well I actually picked up a lot from Jim Wagner (Jim Wagner Pickups/ WCR Pickups) about caps. I found that caps in guitars can REALLY open up the pickups & expand the dynamics. I'm not certain about how it works with pedals & amps but I can only guess that it would do the same to bring out frequencies. Also wiring styles in guitars can create different sounds. A guitar wired in 1950's and 60's specs with caps to match definitely doesn't have the same sonic tonality that modern wiring jobs & caps will have.
@@RokDAWG1 was a industrial/control/commercial IBEW Electrician and now just a old man with time on hand and have lots of parts that I want 2 C different sounds I might come up with have old used/good USA/Japan Caps to try out, Thanks 4 follow up, have been out of music bizz from 80-90s, and and thought back thin there's got 2 B some way of get the sound I wanted, Stay safe brother, nice 2 chat, Ryan
@@Ryan-Hall The best way to do is to dive in and find those sounds! I'm an addicted tone chaser! Haha I'm always willing to pass on any information. Thanks for asking. I'll look forward to hearing what new killer tones you discover!🤘🤘
@Dewd McMan Yeah I definitely don't have any noise issues. I've been fortunate to pretty much always have had really clean sound but this is good information for those who may have run into this very issue.
I liked the tone of the 72 Marshall 50w better. I have a 68 (1200 series)Metro/Friedman 100w head that you can switch off the bright cap with Volume 1 which is also a push/pull to switch between bright cap or none. Another great video!!
This is the video I was waiting for!! Very helpful. I swapped the bright cap on my plexi 10000 times. Now I settled with a 100pf but the switch is the best solution!
This amp mod is like the treble bypass/treble bleed mod you can add to your guitar's volume pot to allow the higher frequencies through the circuit so when you roll off your volume it doesn't get muddy. I do this to a lot of my guitars.
Makes me wonder if it would also be worthwhile to put a resistor in series with the cap (e.g. Kinman mod) that can be switched in and out of the circuit.
add different tubes in the p amp and power tubes, different pup's, cord attenuation, dirty power, mismatched speaker loads, and pick attack and position, and * and it's all good for now.... GREAT stuff Pete! oB
Great topic - really helps to alter the perception about the "dimed" Marshall sound...most recorded sounds you ever hear, are in that "sweet spot," somewhere below 8 on Volume 1. Great video! Thanks Pete!
Thanks for using analogies I can understand. New to all this stuff finally understanding the “high pass” thing but your “transistor radio” comment made my 54 yr old newbie brain go 💡
I dig the no cap with the treble and presence down.He had it set perfect and then he turned the treble and presence up to 6 and screwed it all up.Pete is treble crazy😁
4700-5000pf is also the value used in the Dallas Rangemaster treble booster. It acts very much in the same way, letting through a lot of mids and not just treble frequencies and is a very guitar friendly range. Makes perfect sense that it works in the Bright Cap function as well
Bright cap makes all the difference.Good idea to make it switched that's what I do on the amps I build. You got it right Bro! Thanks for spreading the word Pete! Good video.
In case it hasn't been mentioned already, this is what Fender did with their bright switch starting in the mid 60s on amps like the super reverb. (they also originated the bright bypass cap as dealt with in the vid on the tweeds the Marshalls are based on)
Hi Pete! 👋 Thanks for sharing experience! I have removed that little perpetrator long time ago ,and yet amp was still horribly bright! I know most of people owning JMP’s suffer that problem, and most likely that is why they are here, so i would like to share with them my experience! 🙂 👋 In my case it came up to be the wall voltage! My problems began when I moved in my new house! In the place I lived before was 112V~115V! My new house was ~124V! Well someone will say few volts , does it really matter! Well it definitely did in my case! But hey! I recapped, retubed my amp ,learned how to bias it, and even thing or two more! So I have gained many things from that unpleasant experience! Everything really changed when I bought one of these things called “Variac”! People usually use them to get the so called “brown sound”! No! I did not buy it for that, but still I could use it to get that sound too! And no , It is not one of these bank busters sold for arm and leg! This one was like $60 shipped, and it was around 20A! So there was plenty of current! There are many demonstration videos around here for them! People use them for different things! But be aware! It is big, bulky and heavy piece of hardware! And another important thing ! The readings on the scale and the actual voltage are way off! So don’t count on it! I have nice meter plugged in the second socket to have the actual readings right! And let me tell You! Everything came where it should be! Ass soon as I dropped the voltage between 110V~115V, amp came to its glory! No more piercing sound, and EQ start making a lot of sense and use! So, the higher the voltage, the brighter and brittle the sound become! I have found another thing! My guitars have also voltage preferences! One of my guitars absolutely love around 108V, while another comes at its prime at 115V! I did not try to put back the bright cap tho 😅 Well hope my experience help someone’s struggle of his life! 😉 All best to all, and Happy Holidays ! 👋
Ive been thinkin about it for a long time Pete i have a 1994 1987 head when i think and you Correct me were Reissued so its been with me since 1994 bought it brand New from Manny,s in New York and it just sounds Awesome so i just will Keep it Stock ¡ Thanks for the Info ✌✌👍👍🎸🎸
Yeah, capacitors are based around 'time domain', the larger the cap, the lower the frequency can pass through them. So with a bunch of sliders and different cap sizes you can make a graphic EQ. Simples!
It’s all about the fletcher munson effect, when volume is low, bass and treble are less apparent to the human ear, the cap passes high freq at low volumes to offset the effect, when U turn up all the way it’s simply bypassed
It’s like many other things in the guitar world ,you have to just dial it in to your situation. I tried this on my 71 super lead and it was too bright but that’s just me and my rig you may feel different in your situation… Super great topic… Keep on rockin……
I prefer to remove the 470pf mixer bypass cap so both channels have the same starting point (excluding cathode caps / resistor) and then have a big bright cap on the Bright Channel and a smaller bright cap on the Normal Channel. Then a 300nf on the V2a cathode for a bright cap boost for both channels.
Great video Pete! I do enjoy these geek outs with old Marshall's. Personally I am a fan of no bright cap in my amps but run the treble and presence higher. The Suhr is cool but that old '72 is KILLER!
Nice. It seems your name comes up quite a bit on tech questions. Especially in the Marshall realm. I have the same thing going, Les Paul Custom into a Plexi and was wondering why it sounds kind of nasty on the high end sometimes. I have the presence way down between 1 and 2, bass at about 6, Treble at about 4 and mids at about 2. Seems it's the mid section giving me that tinny sound on the high note with LP in the bridge PU position and a notable difference when I turn down the mids. I have the channels bridged with the Treble channel at about 4 and the normal channel at about 6 to drown tame that bright cap. I do have a nice attenuator going between head and cab for volume control. It really does come down to just fiddling things sometimes, but a valuable walkaway from this video is turn the treble channel up to drown out the bright cap. Cool and thanks.
Great video Pete! This is a very useful component, you can keep it there and it may benefit to your sound or you can cut one leg of it and you've got a sound that you'll like a lot more! My take on this: on Marshall 2204 or 2203 I cut one leg of the 1nF (0.001uF or 1000pF) and get a (to me) more useful tone over a wider gain range. On Marshall 1959 or 1987 I take the 4,7nF (0.0047uF or 4700pF) from the bright channel and put it on the normal channel; may put a 100pF on the bright channel instead. A JTM45 or the like often got a 100pF cap on the bright channel; a 4,7nF in parallell with that is very cool; crunches it up but keeps a lot of warmth in that amp.
The cut off frequency is inversely proportional to the capacitor value. Just like a more conventional high pass filter. The capacitor is technically a bypass capacitor. Play more with the cap values and replace the 680pf cap if you don't like it. That amp is really bright in itself though.
A really interesting upload. I have no fave cap value - different values give equally useful but different tones. BUT.... of the few Marshall's I've tried the pots are not too accurate (+-20%, and seem to vary in their ratios - some lin's seem semi-log and vice-versa) so messing around with the bottom end of the dial (below 2) of the bright channel gives unpredictable results. Lowering the bright cap value decreases overall gain so moves - all other things being equal - the pot setting up a couple of notches to achieve the same volume, thus giving a little more accuracy in its useful range. Hope this makes sense!
Suuuuuuuuper interesting! Thanks for doing this, Pete. And, damn it, now I need to put in my '74 California Jam DVD. Can't get that last riff out of my gourd.
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0.0047uF (microfarad), 4.7nF (nanofarad) and 4700pF (picofarad) are all the same thing if anyone is getting confused.
It might actually help you find a certain brand/type if you want to purchase one for your amp. I like Class 2 Z5U dielectric 1000vdc ceramic capacitors as bright caps in Fender and Marshall amps. Polystyrene and silver mica caps are also popular choices. 500vdc or higher is a good safety margin for AC service, even though bright caps in this position will never see anything over 100vac.
I have a toggle switch on my Ceriatone KK (essentially a Marshall circuit). I'm thinking of going with a 500pf, and a 100pf. I'm on the fence regarding dielectric type. I also have 500pf Sprague polyester caps. People rarely talk about these.
I've been considering a ceramic in the tone stack, so I don't want too many of them in the circuit. What do you think?
Update: The I could barely hear the 100pf. I went with a 4700pf instead.
@@qua7771 That's a big jump in upper mid frequincies. Also the stock value in JCM800's and 2203/4 Lead JMP's to the master volume.
As to answer the previous question, I like ceramic caps in some circuits. Stuff like Valco, Silvertone, Gretsch, Gibson, Magnatone and some Fender amps used a lot of them in the small to mid sized amps. Ceramic caps are microphonic though. You don't want them in a high powered combo amp in every position.
@@matthewf1979 Thank you for your input. I have switches for several options. The High value works for EVH stuff.
I am still a bit confused about the values. Pete demonstrates that going from 4700 pf down to 600pf makes it more harsh. So the lower the value = more bright/thin. Then he demonstrates the lowest value at 100pf and thats the most usable through out the range. How does that makes sense? Am I understanding the values correctly: 4700pf>600pf>100pf?
I didn’t understand bright caps until I purchased the Marshall SV20. The bright cap was so aggressive and harsh that the amp, to me, was unplayable. I had the cap removed and then later purchased a 1987x and had that bright cap removed. Much better in both instances for me.
Just removed my bright cap in my SV20H, sooooo much better! Amp still has plenty of brightness without it. Strat w/ fuzz face user.
Great stuff! I feel like a 'bright cap expert' now in only 20 minutes after knowing nothing about them before. Pete is a _fantastic_ educator.
that would be the dunning kruger effect talking.
@@louiscyfer6944ironic comment
WARNING! Valve amps have huge power capacitors that hold a lot of volts (600+). If you touch them when they are charged they will discharge through you and probably kill you! Unless you learn how to use a discharge tool (easily made) and a multimeter to check it worked don't mess inside your amp. Although Pete mentions briefly at the end I don't think it was stressed enough the potential danger involved in opening your amp. I built my own amp (Fender 5e3) so not saying you can't do this but look up discharge tools and how to use them. Also keep 1 hand in your pocket whilst you are using it so you can't accidentally discharge across your chest.
I've had a whack from 240v mains caps and ouch!! Don't mess with valve amps you could die
I don't want any discharge across my pocket area either but you gave very sound advice.
My advice is to use the motherload of heat shrink in the more dangerous areas, I saw a guy building a jtm45(?) And was like "wow, How have I never thought about this?" and to obviously do the one hand trick.
@@therapist6328certain color discharges are worse than others. Green is really bad, but if it’s red, you’re in serious trouble.
Oh yes. My hand once slightly touched one when my Plexi broke down during recording. Excuse my language, but holy fucking shit
Contents:
With SL-68:
Introduction 0:00 - 5:22
4700pF Bright Cap Jumpered: 5:23 - 6:12
4700pF Bright Cap Not jumpered: 6:13 - 6:30
4700pF Bright Cap Back jumpered, blending in Volume 2: 6:31 - 6:57
No Bright Cap Not Jumpered Adjusting Presence and Treble: 7:04 - 8:08
4700pF Bright Cap Not Jumpered Turning up Volume 1: 8:09 - 9:26
680pF Bright Cap Turning Up Volume 1 Not Jumpered: 9:27 - 10:07
680pF and 4700 pF Bright Cap Comparison Not Jumpered: 10:08 - 11:22
4700pF Jumpered - Adjusting Volume 1 and 2: 11:23 - 12:58
No Bright Cap Adjusting Presence and Treble: 12:59 - 14:44
4700pF Bright Cap Back, tightenting up gain: 14:45 - 15:19
With 1972 50W Marshall JMP:
100pF Bright Cap Not Jumpered: 15:20 - 17:12
100pF Bright Cap Jumpered: 17:13 - 17:58
100pF Bright Cap Not Jumpered: 17:59 - 18:17
Ending and Pete’s Preferences: 18:18 - 19:37
Muchas gracias. Excelente trabajo.
This was excellent. Thanks Pete for the education on how to blend those channels together. I am always appreciative of your video content and quality.
Tried this mod on my JTM45 for about a week and then had my tech take it back off. Just kills the warmth of the tone IMO. I kept preferring the sound when you had it turned off and the treble and presence pushed a bit more. That sound is what makes those amps incredible to me. All good tho, still learned something.
Great video! I am a huge fan of the bright cap! I know lots of people who remove it on Marshalls… but that’s like a HUGE part of the Marshall sound and a big no-no for me. I just finished a build a few months ago centered on a 1987 (utilizing original 60’s/70’s parts, Piher resistors, Mullard caps etc), but instead of having the “normal” channel, I added a switch to route the bright channel into v1b, so it switches into a 2204 (even switches a master volume in/out). But for this amp I wanted more control on the bright cap - it can get a bit raunchy (depending on the value) when you start dialing the gain back, so I came up with a unique (at least unique to me) mod for this…
As per usual, I connected that output of stage 1 to the GAIN (1MΩ) pot input, then from there I connected my 1000pF cap to an input of another (dedicated) 1MΩ pot. Then the output of that additional pot gets wired back to the GAIN pot’s output (middle lug). So it’s like having a bright cap in it’s usual place (between the input and output lugs) with a variable resistor in series with the cap to allow me to control the amount of bright cap that is passing to stage 2. Sort of a blend knob I suppose?
It’s great for when I want to dial the GAIN knob back to 5, I pull that additional pot (“tone” pot) down to 5 or 6 so it still has that bright Marshall sound, just a bit more useable in my opinion.
Really interesting and well demonstrated (as always) vid, Pete. Thanks for taking the time to do this. I’ve been in two minds about getting into this with my 1987x which I currently use with no bright cap but have the 4700uf on a push pull. I think I’ll just leave it alone now having heard a real world comparison. Rock on!
You can stack caps in parallel too, and if you are super lucky you can find a concentric pot and rotary switch so you could stack from no bright cap to 2,3,4 or 5 different values. You can make a lot of sweet spots that way.
Thanks for the tips Pete!
I removed the 470pf and dropped a 4700pf on my Plexi clone, there is a HUGE difference even at low volumes. i felt the 4700pf provided all the frequencies even at low volumes, compare to all-treble that the 470pf provide….even the 1000pf sounds shrilly to my ears..
I had a PC board JCM 800 and it didn't sound great... Using my electronics and electrical background knowledge, I tore it apart and built a point to point wired JCM 800 along with custom wound mercury magnetics transformers... What an amazing difference!!! Then I played with caps and pots and installed a cap switch knob for exactly this reason. That exact amp went to Germany with "Jim" whatever his name was (Opening act for Anthrax in Germany that year) and Scott Ian asked if I could make a 100W version.. hence I began building 6-50W and 6-100W "Marshall" amps and experimenting with the 'Plexi" circuit which was good but... a little tweaking and WHOA!! it breathed FIRE!!! Anywhoo, cool video that brought back some memories of tweaking amps with just different pots and caps! Cheers dude! (1st 50W amp took 40 hours to build and another 40 hours to tweak on the scope!)
Great video as always! The way I approach it is using the cap to decide the cutoff frequency, as you clearly explained, and using an optional resistor is series to attenuate the signal going through the bright cap, therefore defining the sweet spot of the Volume I.
That way, for example, a 500pF cap can sound balanced when Volume I is at lower settings.
8:00 ? why on earth would you want to change that???? That is classic Marshall 100%. Full on in your face chunky distorted growly with just enough bite.
Always impressed with and appreciate your talent, knowledge, and practical no-nonsense videos, Pete. Many thanks!
When you have no bright cap and turn the amp volume down so that it is clean there is a treble roll off due to the capacitance in the tubes, lots of people like this treble roll off. Using 90-100pf bright cap keeps the top end more level through out the range of the volume control. That is why that value was chosen and used by many since. Adding 680 - 1000 - 4700uf makes the volume control a tone control.
The original idea was to retain some brightness as the level was rolled off. Fender maybe had a better approach with their tapped pots. They used them multiple times in varying tap percentages & tapers. There is the brown & blonde hi fi tone stacks and the 90% treble bleed cap on their 1970s master volumes, but no all of their master volume amps got that pot. The Bassman amps never got it. The volume is always a bit of a tone control and it varies with the impedance of your guitar output or whatever is last in you effects or pedal board signal chain. Sometimes a just clean buffer is a good idea. It sort of equalizes everything out so a Strat & Les Paul can show the amp's input the same impedance.
The ever changing quest and adventure to find the right sound . And it does make a difference . Thanks for doing this Pete .
Awesome! I have a '86 Model 1987 50 four hole. Now I'm going to check my bright cap! Fun.
My understanding, the reason you like the no bright cap and presence sound best at 13:30 is because the presence cuts the fizz and ice picks at the power tube stage leaving behind the good stuff, the bright cap and treble pot cut at the early preamp stages which cuts out and doesn't allow the upper harmonics to develop, the presence control cuts all the fizz and ice picks at the last power tube stage and leaves all that beauty harmonic distortion behind for you to enjoy
Very cool demonstration, Pete. I'm glad that you like and played "stone in love". The song is simple but brilliant and the reason I picked up the guitar. Neal is a ferocious guitar player when he wants to be and it shines through in this song.
The solo is to me, still the epitome of what a great "song within a song" solo should be along with a monstrous guitar tone :) kudos my friend
The first Journey was way better, before they went bubblegum pop. Neil really went wild then!
@@michaelcraig9449 Indeed! Infinity was the early peak... Neil's solos are so well constructed and played. Some classic tunes from that lineup.
When I build amps, and voice them at the end, I spend the most time with the treble cap on the volume and mixing resistors bright caps. They get the excitement in the sound, but must be voiced for the volume you expect to play at, which is difficult. That’s why I have often put three way switches in for my amps for the caps.
I love all the tones on my stock 71 1987 from about 3-7 on the bright volume, straight into the top left input no patching. On the lower settings just use the guitar tone controls to tame the high end. Helps that I’m running through a 68 straight cab with Pulsonic Greenbacks as they are nice and warm. Modern speakers or even Blackbacks make it much harder to use these amps this way.
The only time I’d ever jump channels is if I wanted a clean pedal platform….. and who buys a classic Marshall for that !!
EE chiming in here.... One way to view this cap in parallel with the pot is that it is a frequency dependent resistor. The capacitor "resistance" is known as the reactance. The formula is Xc= 1/ (2 * pi * Freq * C).
where pi is 3.14, Freq in Hz, C in uF (1e10-6) or pF (1e10-12). The result is in ohms. Another thing to remember when placing resistors in parallel is the combined resistance is always lower than the lowest resistor value. So if the bright cap resistance is getting lower then it dominates the signal path and routes the higher frequencies around the pot.
Lastly, if possible use a metal film capacitor type vs. a cheap ceramic as the bright cap or (bleed cap in the guitar). There are technical reasons for this but in the end they sonically sound better.
I experimented with this a while back and tried something I haven't seen anyone else describe. I left the original cap in place and added a potentiometer to control how much signal was getting to the cap (I think I placed it in series but I don't remember for certain; but parallel should as well). So I was getting the same frequency cutoff but could control the signal level. I found this to be so effective and satisfying (and especially useful at different volume levels) that I considered for while installing the pot permanently in the amp. (Maybe replace Presence with a concentric pot (two pots in one) to avoiding drilling?) I remember thinking that it was actually more effective than the Presence control.
Your Marshall sounds like mine. It's my 3rd since I got my first in London in '71 when of all guys Ron Wood was using one and put me onto one he seen from a studio I could get relatively cheap. At 75 I hope this one sees me out, LOL.
That Suhr sounds pretty amazing in any configuration!
Fantastic video. It is helping me get familiar with a new amp that also has a switch that allows you to choose between three bright cap settings--one of which is no bright cap. Super helpful examples/tones--thank you!
With a Fender if I don’t clip, I just turn the amp to 6.5 and put a passive volume pedal at the end or before the delays and such. It’s bypassed but I’m sending my levels in so it’s clean or break up at full throttle. I also makes sure I have a buffer pedal in the chain before. I like a set and leave it approach, but the mods are cool as well, just to get rid of it at lower gains. But there’s a lot of ways to use or get around it. As long as I don’t have to gain stage every time I move my amp all my pedals and amp settings…I’m good!
You can easily make a "cap switcher" box to determine which value sounds best in your particular Marshall.
The bigger cap sounds great, but no cap gives you fantastic cleans. I think I'd just clip it. That's a nice mod though!
Hi, i tried it on my origin 5, it works well. Thank you.
Those crazy nights i do remember in my youth….
One of my favorite opening riffs-
Great video Pete! - 👏🏻🔥
Just a great song.
Also that bright channel coupling cap makes a difference.. many of the marshalls used .0022 for the treble channel where others used the .022. I never liked the .0022..they just seemed way to bright and harsh.. but depends on other factors too. Others might love it..
Mine has a .022uf cap, and the bass is way out of control. With a coupling cap that large there is sound being produced below hearing range, and the speakers capability. The only way I could see it being tolerable is if the power amp has very small coupling caps. If so that would explain why the .0022uf channel sounds thin.
@Dewd McMan Is this a drunken reply? Holy crap!
Great vid. I think a lot of people don’t have a good understanding of this subject thinking a lower value bright cap will have less treble when a higher value will actually sound better because it lets more high mids through. I just changed my 470 p. to 1nF in my Ceriatone 2204 and now it sounds like a Marshall.
Great video! You explained the bright cap in a very easy to understand way and then did a superb job demoing it. Thanks again, these videos are fantastic. 👍🏼
I have an older Peavey classic Amp . It has a Brite Switch I love it !!
Years ago I lifted one leg of the bright cap in my 77 JMP and it completely transformed the amp for the best. The other leg is still soldered on, so if I sold it and the buyer wanted the cap in, you just bend it back into place and solder it back in place.
Tried clipping in a 4700 pf. I use the SL68 mainly as a pedal platform. I am more used to Friedman, JVM, XTC distortion so I use pedals on the SL68 for distortion. The 4700 sounded cool without pedals. Definitely need to roll off treble, presence and blend in channel 2. But with pedals it was pretty harsh. I’ll use a push pull if I keep it in. Great video. Thanks.
Awesome Pete! I've recently discovered the whole "cap" tone differences in both guitars and amps over the last few years. Makes such a HUGE difference! Your tones here are KILLER!
ON A SIDE NOTE: I actually started shooting my video to showcase my old amp that Neal Schon endorsed in the early 90's & you and I played the same Journey and Zep tunes! Oh and I have my black Les Paul! Haha! I think I'll reshoot my opening.
Hey Arthur, seen U on chat with Pete,
U have good advice on putting caps and resistors in the guitar or maybe to upgrade pedal or none tube Amp combos like Peavey's or Roland, Fender?? Just throw it your way and leave link would be Kool 2 C what u do and all, seen Ben Coombs show, and always like seeing others,
TY, good 2 meet through Pete, he's got the right stuff,
@@Ryan-Hall Hey! Well I actually picked up a lot from Jim Wagner (Jim Wagner Pickups/ WCR Pickups) about caps. I found that caps in guitars can REALLY open up the pickups & expand the dynamics. I'm not certain about how it works with pedals & amps but I can only guess that it would do the same to bring out frequencies. Also wiring styles in guitars can create different sounds. A guitar wired in 1950's and 60's specs with caps to match definitely doesn't have the same sonic tonality that modern wiring jobs & caps will have.
@@RokDAWG1 was a industrial/control/commercial IBEW Electrician and now just a old man with time on hand and have lots of parts that I want 2 C different sounds I might come up with have old used/good USA/Japan Caps to try out,
Thanks 4 follow up, have been out of music bizz from 80-90s, and and thought back thin there's got 2 B some way of get the sound I wanted,
Stay safe brother, nice 2 chat,
Ryan
@@Ryan-Hall The best way to do is to dive in and find those sounds! I'm an addicted tone chaser! Haha
I'm always willing to pass on any information. Thanks for asking. I'll look forward to hearing what new killer tones you discover!🤘🤘
@Dewd McMan Yeah I definitely don't have any noise issues. I've been fortunate to pretty much always have had really clean sound but this is good information for those who may have run into this very issue.
I liked the tone of the 72 Marshall 50w better. I have a 68 (1200 series)Metro/Friedman 100w head that you can switch off the bright cap with Volume 1 which is also a push/pull to switch between bright cap or none. Another great video!!
This is the video I was waiting for!! Very helpful. I swapped the bright cap on my plexi 10000 times. Now I settled with a 100pf but the switch is the best solution!
Thank you, Pete! It is so good to see you stepping up!! Impressive…
Excellent Video Pete!!!! Great playing and tones, and man I never knew so much about the BC, till Now!! Stay Groovy and Keep on Rockin' Bruddah!!
14:22 one of my favorite Blackmore riffs 🤘🏼
This amp mod is like the treble bypass/treble bleed mod you can add to your guitar's volume pot to allow the higher frequencies through the circuit so when you roll off your volume it doesn't get muddy. I do this to a lot of my guitars.
Makes me wonder if it would also be worthwhile to put a resistor in series with the cap (e.g. Kinman mod) that can be switched in and out of the circuit.
add different tubes in the p amp and power tubes, different pup's, cord attenuation, dirty power, mismatched speaker loads, and pick attack and position, and * and it's all good for now.... GREAT stuff Pete! oB
Great topic - really helps to alter the perception about the "dimed" Marshall sound...most recorded sounds you ever hear, are in that "sweet spot," somewhere below 8 on Volume 1. Great video! Thanks Pete!
Volume 1 around 7 8 on volume really is a sweet spot
Thanks for using analogies I can understand. New to all this stuff finally understanding the “high pass” thing but your “transistor radio” comment made my 54 yr old newbie brain go 💡
You just made me realize some people might not know what a transistor radio is 😂 we are older guys
Great video as usual and bonus points for the "Stone in Love" intro. Will always love that song.
Great video. I understand MUCH more about the bright cap now.
I dig the no cap with the treble and presence up.
I dig the no cap with the treble and presence down.He had it set perfect and then he turned the treble and presence up to 6 and screwed it all up.Pete is treble crazy😁
4700-5000pf is also the value used in the Dallas Rangemaster treble booster. It acts very much in the same way, letting through a lot of mids and not just treble frequencies and is a very guitar friendly range. Makes perfect sense that it works in the Bright Cap function as well
Bright cap makes all the difference.Good idea to make it switched that's what I do on the amps I build. You got it right Bro! Thanks for spreading the word
Pete! Good video.
Lots of good stuff here. Really a great video to show how the 2 volume pots work together. Thanks Pete!!!
Cool that you shared your capacitor experiment on the YT, It does provide insights otherwise I'd not indulged.
thnx for the info on what alot of people wouldn t think about,...including me,..makes a big,big difference, wow it seems the 470 is the most versatile
In case it hasn't been mentioned already, this is what Fender did with their bright switch starting in the mid 60s on amps like the super reverb. (they also originated the bright bypass cap as dealt with in the vid on the tweeds the Marshalls are based on)
Very interesting and useful information thanks P.T. 🙂
Hi Pete!
👋
Thanks for sharing experience!
I have removed that little perpetrator long time ago ,and yet amp was still horribly bright!
I know most of people owning JMP’s suffer that problem, and most likely that is why they are here, so i would like to share with them my experience!
🙂
👋
In my case it came up to be the wall voltage!
My problems began when I moved in my new house!
In the place I lived before was 112V~115V!
My new house was ~124V!
Well someone will say few volts , does it really matter!
Well it definitely did in my case!
But hey!
I recapped, retubed my amp ,learned how to bias it, and even thing or two more!
So I have gained many things from that unpleasant experience!
Everything really changed when I bought one of these things called “Variac”!
People usually use them to get the so called “brown sound”!
No! I did not buy it for that, but still I could use it to get that sound too!
And no , It is not one of these bank busters sold for arm and leg!
This one was like $60 shipped, and it was around 20A!
So there was plenty of current!
There are many demonstration videos around here for them!
People use them for different things!
But be aware! It is big, bulky and heavy piece of hardware!
And another important thing ! The readings on the scale and the actual voltage are way off!
So don’t count on it!
I have nice meter plugged in the second socket to have the actual readings right!
And let me tell You!
Everything came where it should be!
Ass soon as I dropped the voltage between 110V~115V, amp came to its glory!
No more piercing sound, and EQ start making a lot of sense and use!
So, the higher the voltage, the brighter and brittle the sound become!
I have found another thing! My guitars have also voltage preferences!
One of my guitars absolutely love around 108V, while another comes at its prime at 115V!
I did not try to put back the bright cap tho 😅
Well hope my experience help someone’s struggle of his life!
😉
All best to all, and Happy Holidays !
👋
That is the cleanest I've seen the LP Custom look. Great tones.
Yup. 13:26 is the tone.
Ive been thinkin about it for a long time Pete i have a 1994 1987 head when i think and you Correct me were Reissued so its been with me since 1994 bought it brand New from Manny,s in New York and it just sounds Awesome so i just will Keep it Stock ¡ Thanks for the Info ✌✌👍👍🎸🎸
Sounds immensely better with the cap! Invaluable info. Thanks!
Great vid, knowledge and playing! Thanks!
Hit the like button in less than 10 seconds for that opening riff. Stellar playing as usual.
This amp series is always full of knowledge. I love these!
Great video as usual! And EVERY setting you played sounded great -- as usual!!!!!!
Thanks for the info Pete. So simple and so effective.
*Timeline **11:20** shows that one's facial expressions add some good frequencies to the sound Pete!*
I play through valve PAs so it could help me.I play clean which isnt really covered here but presumably it's about the same effect
Yeah, capacitors are based around 'time domain', the larger the cap, the lower the frequency can pass through them. So with a bunch of sliders and different cap sizes you can make a graphic EQ. Simples!
Pete, I find your videos so interesting in that although I don't know much about the electronics of amps or guitars, I found it to be instructional.
Thanks for sharing your knowledge, experience and thoughts on this capacitor subject
Pete, thanks so much for sharing your knowledge. So cool to learn from you.
It’s all about the fletcher munson effect, when volume is low, bass and treble are less apparent to the human ear, the cap passes high freq at low volumes to offset the effect, when U turn up all the way it’s simply bypassed
It’s like many other things in the guitar world ,you have to just dial it in to your situation. I tried this on my 71 super lead and it was too bright but that’s just me and my rig you may feel different in your situation… Super great topic… Keep on rockin……
I prefer to remove the 470pf mixer bypass cap so both channels have the same starting point (excluding cathode caps / resistor) and then have a big bright cap on the Bright Channel and a smaller bright cap on the Normal Channel. Then a 300nf on the V2a cathode for a bright cap boost for both channels.
Cool video. I know more about Marshalls amps and bright caps now!
I’ve always liked a sort of scooped sound but without much bass. So mid and bass down all the way and treble between 3 and 4, and cranking the volume.
Any idea what Dave Friedman uses in the Small Box? Same thing, 3 way switch, off, bright, brighter… nothing in the manual with which cap is which….
Small Box is 250pf - No cap - 500pf, so bright-off-brightest or the other way around...
Great video Pete! I do enjoy these geek outs with old Marshall's. Personally I am a fan of no bright cap in my amps but run the treble and presence higher. The Suhr is cool but that old '72 is KILLER!
Nice. It seems your name comes up quite a bit on tech questions. Especially in the Marshall realm. I have the same thing going, Les Paul Custom into a Plexi and was wondering why it sounds kind of nasty on the high end sometimes. I have the presence way down between 1 and 2, bass at about 6, Treble at about 4 and mids at about 2. Seems it's the mid section giving me that tinny sound on the high note with LP in the bridge PU position and a notable difference when I turn down the mids. I have the channels bridged with the Treble channel at about 4 and the normal channel at about 6 to drown tame that bright cap. I do have a nice attenuator going between head and cab for volume control. It really does come down to just fiddling things sometimes, but a valuable walkaway from this video is turn the treble channel up to drown out the bright cap. Cool and thanks.
🌟🌟🌟🌟🌟 luv the 4700 pf.
Cool vid! Also, that's one awesome looking Les Paul!
Sounds great!
Great video Pete! This is a very useful component, you can keep it there and it may benefit to your sound or you can cut one leg of it and you've got a sound that you'll like a lot more!
My take on this: on Marshall 2204 or 2203 I cut one leg of the 1nF (0.001uF or 1000pF) and get a (to me) more useful tone over a wider gain range. On Marshall 1959 or 1987 I take the 4,7nF (0.0047uF or 4700pF) from the bright channel and put it on the normal channel; may put a 100pF on the bright channel instead.
A JTM45 or the like often got a 100pF cap on the bright channel; a 4,7nF in parallell with that is very cool; crunches it up but keeps a lot of warmth in that amp.
Great video Pete! I'm almost always a no bright cap guy.
The cut off frequency is inversely proportional to the capacitor value. Just like a more conventional high pass filter. The capacitor is technically a bypass capacitor.
Play more with the cap values and replace the 680pf cap if you don't like it. That amp is really bright in itself though.
Top notch. You should get in touch with the TPS lads and get 'em to mod their Marshall, which they've been meaning to get done for ages.
Awesome stuff Pete! Thanks!
A really interesting upload. I have no fave cap value - different values give equally useful but different tones. BUT.... of the few Marshall's I've tried the pots are not too accurate (+-20%, and seem to vary in their ratios - some lin's seem semi-log and vice-versa) so messing around with the bottom end of the dial (below 2) of the bright channel gives unpredictable results. Lowering the bright cap value decreases overall gain so moves - all other things being equal - the pot setting up a couple of notches to achieve the same volume, thus giving a little more accuracy in its useful range. Hope this makes sense!
HOLY MOLYYY! that guitar sound of stone in love was spot on! so good!
It sounds awesome. Great playing as usual.
Great job Pete. Man I love that Schon riff. So good 👍
It’s also why. a cut control aft the PI works so well
With the 100 microfarad on the Marshall, you've got to be on 6 and above on vol. 1 to sound good. Best sound at 14:20 to my ear... !
Suuuuuuuuper interesting! Thanks for doing this, Pete. And, damn it, now I need to put in my '74 California Jam DVD. Can't get that last riff out of my gourd.
okay I use to work for Martin and I make music and help Musicians Globally and I really dig what you did here. Pretty cool. I'm on your team totally
Nice! Just bought an Origins 50 to run my BE od and probably Helix - I’ll check this out
This works the same on the tone pot cap on your guitar(if you have one). Great info here as always!