I just picked up a basically new BJr IV. The newest versions from late 2019 have the new very different Bias Circuit. Sounded OK but that Brit Cap took some paint off the wall. Anyway.... I tore into it. First replaced the Cup Capacitor from .0022 to .022. The new circuitry replaced the .0022 to .022 in the last stage. Then I changed the Marshall tone stack (.022/.022) to the classic Fender tone stack (.1/.047...Twin). Then shorted out the Mid control ctlr ctr cx to left cx. And to top it off I took out the .100pf paint scraper brite cap and put in a .047pf cap on a switch. What a wonderful difference!!!! Now a small Twin with good bass, working Treble and Mid control with a brit switch that just adds more Fender sparkle. I would have never been able to do this without your videos. You gotta hold your mouth right to get that PCB (black) out. And the solder they are using is hard to vacate. Would be easy to burn some lift if not very careful. Thanks!!
A hard-rubber (soft-plastic) dead-blow mallet filled with lead shot is a great tool for applying a little persuasion or an "attitude adjustment" to a bent flange or sheet-metal chassis. Every tool-chest needs one !
I got one from a friend and one fire up that’s what it did! One power tube exploded damaging the amp. Fried chicken in parts of the board. A friend rebuilt the poor diodes and replaced all the caps with high quality ones as the factory grey caps are poor quality. Now it’s back and sounding awesome!
I have installed a MM output tranny and choke on a couple of those and it made an appreciable difference. But the best tone I got from one of them was when I plugged the speaker into a 5E3 cab with a Weber 50 watt Blue Dog. It was an amazing sound.
@@uncledoug9934 mainly what my amp tech recommends. But compare a stock tweed with the Jensen C12N against a stock Blues Junior to hear the difference.
I used to have a jensen 12 inch p12q or p12k , can't remember exactly. I change it to an eminence swamp thang 150w speaker and it's amazing. Headroom ! Rich lows! And super clean as it breaks at super high volumes. Neo speakersbare good only because they are lightweight. I would never sacrifice this sound for 2,5 kilos weight difference
Quick question - the issue with the tubes running hot - isn't that what gives them the overdriven breakup? So if that's "fixed" then they won't growl? If the answer is "that is correct" I almost feel like I'd rather go through the tubes faster in order to get that sound. My volume lives between 10 and 12, using the Fat as a solo boost and oh lord I love the sound. If fixing the bias undoes that -- it's kind of taking away the golden egg that makes this amp sing? Happy to find out if I'm wrong.
I'm close to picking up a Blues Jr for a couple hundred bucks, seller says the speaker sounds 'scratchy', but all else works...just heard you mention 'cooling the bias' on these...do you have a video on the Blues Jr? Thanks for the excellent content!
Yep, that's the unit in the US customary system. (Newton meters in metric.) How many pounds of force are you exerting on a rod one foot away from the center of rotation.
i had to replace my tube board this week in my blues jr!! checked for cracked solder joint, which it had on all but 6 solder joints. i was going to just reflow them but when i did the pads lifted right off!! so new board and good leaded solder and shes sounding good as ever! would you recommend not using the stock output tube retainer? and just for back story it has a full bill m kit with adjustable bias.
Listening to an ES 335 through this BJ I think it would have been interesting to contrast it with a Tele or Strat - with my BJ III (an Eminence Swamp Thang having replaced the Fender stock speaker) I have significantly more low end with an ES 335 than with a Tele or Strat. So changing guitars will require adjusting (at least) the Bass settings. Though I haven't yet modified the R51 to cool the bias (which I will eventually thanks to you repeatedly pointing this out) I'm somewhat surprised to see that so far (after about 10 years!) there seem to be no visible traces yet of too hot output tubes causing trouble to the PC boards or the tube sockets soldering points. But maybe that's depending on how heavily these amps are being run (or driven) after all. Also I actually feel that I haven't been forced to get new EL 84s too often in the past. Nonetheless it seems reasonable to cool the bias, anyway, as I admittedly do feel the the heat at the back at the amp when I turn it off after 1-2 hours of weekly rehearsal with the band... ADDENDUM: I did take off the back off the amp again today to take one more closer look and I noticed that there IS indeed a distinct discoloration of the orange print on the right hand EL 84 output tube, which suggests that it is actually running too hot - like you said it would! I'll have to look at this soon and add that 82K resistor piggybacking R51 to cool the bias... So thanks again for making me aware of this fact! Also - having the amp at home - noticed some tube rattle with V1 so I guess I have to rplace that one, too...
Lyle, I'm perplexed - every amp I've ever owned has the speaker mounted to the baffle with 4 screws, yet the basket has 8 holes. Do the speaker manufacturers intend their products to be mounted with 8 screws? if not then why are there 4 extra holes in the speaker? The only reason I can think for the extra holes is to allow more flexibility in positioning the wire connection tab. What do you think?
You didn't mention speaker break in. I know that makes a ton of difference. Also, what do you think of putting a 125 watt speaker in a 18 watt amp? Will it have the ump to get the speaker loosened up?
@@PsionicAudio I do not agree. When I put a new cannabis rex eminence in my BJ, I didn't like the sound at all. The sound was not good, fizzy and boxy, with no bass. And after several weeks, the sound became wonderful. It all depends on the speaker. Cannabis rex takes a long time to break in, for example.
Here's an amp that actually needs a standby switch and doesn't have one. Lol Fender, you put a standby switch in shiploads of amps that should not have one and then on the odd amp that does actually need one you don't bother omg lol. My MkIV series 2 blew a tube within weeks and fried the board. Good job Fender, you also know they run too hot and still haven't fixed the problem even after having another attempt in the MkIV series 2.
I’m no expert but the new speaker in its current setup isn’t my favorite. In the name of science it will be interesting how it sounds with the amp wrapped up. Anyway always enjoy your approach.
Greenbacks are great in Blues Jrs, Swamp Thangs are a bit modern for my preference in a clean Fender amp. Both are absolutely amazing speakers though, they just do very different things
I tried 4 or 5 different speakers in my Blues Jr. My two faves are a Weber Blue Dog Alnico 30 watt speaker with the bell cover removed. It will fit just barely. Or the WGS ET65 speaker which is a Creamback clone. The Creamback clone is what I've liked best for live gigs. The Blue Alnico is best for recording.
Are the threaded fasteners for holding the speaker to the baffle board actual T-nuts with the flanges inbetween the front of the baffle and the speaker cloth?? If they are, kudos to Fender for doing it that way. But, if the inserts are merely threaded into the particle board baffle, then 😖😖😖 #@%&!! .....and regardless I would prefer to see 8 bolts rather than just 4 (even for a lightweight Neo-mag speaker, but especially if the speaker has a large heavy magnet). Not to mention that Torx-head bolts would be easier to use than Philips heads, easier to remove and reinstall/tighten without slipping or stripping.
Noticed when checking speaker screw tightness on Fender DR, that there is a substance like fingernail polish on each screw...? Is this a warranty trick...? Couldn't believe how many loose screws/nuts there were...!!! Thanks for that video that pointed out these things😉😎👍 😎👍
@@PsionicAudio I see...thanks... However... If they tightened them enough...they wouldn't need to put the fingernail polish on them to begin with...? 😉😎👍
I have a Blues Junior Mark IV... what resistor value should I use to "fix" the bias? The same value as the Mark III? Love your videos by the way. Thanks!
Not sure as I’ve heard reports of some fixed bias IVs and some cathode bias IVs, though I have not had any cathode bias ones come in. If it’s fixed bias, yes, 68K across R51.
The Texas Heat was my favorite in the Blues Jr. and came highly recommended at the time I owned one. It had way more bass than the Neo demonstrated here. I wonder if the owner purchased it by mistake or something.
Have a Texas Heat on the shelf waiting to go into my BJ. Do you think the amp has enough power to drive the 150 watt Eminence? Was it to your liking and why? Appreciate any info you can give, and I would answer any ?? you may have too.
@@averagegearreviews4109 I've had a Texas Heat in my Blues Jr for a few years. It drives it just fine. Plenty of lows. You won't get speaker break-up for sure but i rely on pre-amp distortion. Compared to Blues Jrs I hear on You Tube, I think mine is cleaner. But the amp is heavier than any OEM speaker.
@@genebrenner855 Good Morning, that's a fine point about speaker break-up. I too use pre-amp and pedals. I did some common mods to a TS-9 and it makes that amp sing. Thanks again and enjoy your day!
Good luck choosing a speaker it's kind of a One-Shot deal. You can ask that question and get a hundred different answers. there is no place to demo them that's the problem.
@@stringlocker , yeah your right! Everything else in life you can demo first and decide, guitars, amps, cars and clothing. Hard to pull the plug for $150 -$300 not having an idea.
@@kmichaelp4508 You would hope the amp companies would do that research for us but they don't they put the cheapest thing they can find in there. Boutique amp companies do the research. I guess we're a little bit to blame are we ever satisfied.
@@dangitdan9938 Yeah I understand the principles, just need to make sure that I'm not going to be electrocuted. Now just need to decide if a Greenback or a Creamback is the way to go. (I think it's the Greenback)
EL84 amps are pigs on tubes .I have owned at least an half dozen el84 amps all at a same time & all of them had the original el84's fail & had to be replaced within one year .
Place the amp *designers*, not the entire category of "EL84 amps". The amps are invariably designed to push the tubes way harder than they can take for any length of time, especially today's modern Russian and Chinese-made tubes.
@@davidfuller581 , They might have gotten away with this kind of circuit design and hot biasing 60 years ago when you could go down to the local tv/radio repair shop or perhaps even the drugstore and buy some Mullard or Telefunken EL84'S every 6 months or as needed, but nowadays with Russian and Chinese tubes and ultra high wall voltages, they need to rethink their designs.
? I have the Monoprice/Harley Benton State Right 15w amp. It is cool biased, but the gain is extremely sensitive and goes very gainy after increasing the gain nob to 2, it's like the master volume. Because at 1, and you turn the amp up with the volume, it is pretty low in volume, but nice and clean. Once you get it to 2, you are already in crunch. How can I affordablely lower that gain and clean it up going past 2? Oh. It has the original speaker. The Celestion Seventy 80 12in.
@@PsionicAudio true, but it would be worth it in the long run wouldn't it? Having an amp that I already paid off and improving it little by little to get a quality sounding amp. Yes, it will only be worth what it is worth, but the end result is what I want. Since I will not sale it because its not worth much.
I just picked up a basically new BJr IV. The newest versions from late 2019 have the new very different Bias Circuit. Sounded OK but that Brit Cap took some
paint off the wall. Anyway.... I tore into it. First replaced the Cup Capacitor from .0022 to .022. The new circuitry replaced the .0022 to .022 in the last stage.
Then I changed the Marshall tone stack (.022/.022) to the classic Fender tone stack (.1/.047...Twin). Then shorted out the Mid control ctlr ctr cx to left cx. And to
top it off I took out the .100pf paint scraper brite cap and put in a .047pf cap on a switch. What a wonderful difference!!!! Now a small Twin with good bass,
working Treble and Mid control with a brit switch that just adds more Fender sparkle. I would have never been able to do this without your videos. You gotta
hold your mouth right to get that PCB (black) out. And the solder they are using is hard to vacate. Would be easy to burn some lift if not very careful. Thanks!!
Wow the eminence sounds great on it
A hard-rubber (soft-plastic) dead-blow mallet filled with lead shot is a great tool for applying a little persuasion or an "attitude adjustment" to a bent flange or sheet-metal chassis. Every tool-chest needs one !
The neo speakers are known for cutting the lows. I like the Celestion cream back or the Alnico Gold speaker in that amp.
Celestion cream back is not one, but a series of speakers.
I got one from a friend and one fire up that’s what it did! One power tube exploded damaging the amp. Fried chicken in parts of the board. A friend rebuilt the poor diodes and replaced all the caps with high quality ones as the factory grey caps are poor quality. Now it’s back and sounding awesome!
I have installed a MM output tranny and choke on a couple of those and it made an appreciable difference. But the best tone I got from one of them was when I plugged the speaker into a 5E3 cab with a Weber 50 watt Blue Dog. It was an amazing sound.
The Jensen C12N is the best speaker for a Fender Blues Junior
What, in your opinion, makes it the best?
Why. What foes it do hetter than the O.E.?
@@uncledoug9934 mainly what my amp tech recommends. But compare a stock tweed with the Jensen C12N against a stock Blues Junior to hear the difference.
@@uncledoug9934 I think it is a warmer sound; more classic
I used to have a jensen 12 inch p12q or p12k , can't remember exactly. I change it to an eminence swamp thang 150w speaker and it's amazing. Headroom ! Rich lows! And super clean as it breaks at super high volumes.
Neo speakersbare good only because they are lightweight. I would never sacrifice this sound for 2,5 kilos weight difference
Quick question - the issue with the tubes running hot - isn't that what gives them the overdriven breakup? So if that's "fixed" then they won't growl? If the answer is "that is correct" I almost feel like I'd rather go through the tubes faster in order to get that sound. My volume lives between 10 and 12, using the Fat as a solo boost and oh lord I love the sound. If fixing the bias undoes that -- it's kind of taking away the golden egg that makes this amp sing? Happy to find out if I'm wrong.
No, amps don’t need to be dying to sound cool.
@@PsionicAudio So biasing the amp won't change the sound? Thanks for responding.
Agree with your sonic perspective.. The ET65 seems to have that little bit of midrange notch that works really well through that cab.
The Celestion G12M-65 cream chassis sounds very good, and the Jensen C12N also.
I'm close to picking up a Blues Jr for a couple hundred bucks, seller says the speaker sounds 'scratchy', but all else works...just heard you mention 'cooling the bias' on these...do you have a video on the Blues Jr? Thanks for the excellent content!
We always called it Foot Pounds. My brother did auto mech for many years before aviation. Too many head gaskets.
Yep, that's the unit in the US customary system. (Newton meters in metric.) How many pounds of force are you exerting on a rod one foot away from the center of rotation.
For smaller fasteners, we use inch-pounds.
i had to replace my tube board this week in my blues jr!! checked for cracked solder joint, which it had on all but 6 solder joints. i was going to just reflow them but when i did the pads lifted right off!! so new board and good leaded solder and shes sounding good as ever! would you recommend not using the stock output tube retainer? and just for back story it has a full bill m kit with adjustable bias.
Listening to an ES 335 through this BJ I think it would have been interesting to contrast it with a Tele or Strat - with my BJ III (an Eminence Swamp Thang having replaced the Fender stock speaker) I have significantly more low end with an ES 335 than with a Tele or Strat. So changing guitars will require adjusting (at least) the Bass settings.
Though I haven't yet modified the R51 to cool the bias (which I will eventually thanks to you repeatedly pointing this out) I'm somewhat surprised to see that so far (after about 10 years!) there seem to be no visible traces yet of too hot output tubes causing trouble to the PC boards or the tube sockets soldering points. But maybe that's depending on how heavily these amps are being run (or driven) after all. Also I actually feel that I haven't been forced to get new EL 84s too often in the past. Nonetheless it seems reasonable to cool the bias, anyway, as I admittedly do feel the the heat at the back at the amp when I turn it off after 1-2 hours of weekly rehearsal with the band...
ADDENDUM: I did take off the back off the amp again today to take one more closer look and I noticed that there IS indeed a distinct discoloration of the orange print on the right hand EL 84 output tube, which suggests that it is actually running too hot - like you said it would! I'll have to look at this soon and add that 82K resistor piggybacking R51 to cool the bias... So thanks again for making me aware of this fact!
Also - having the amp at home - noticed some tube rattle with V1 so I guess I have to rplace that one, too...
I’d like to bring you my 90’s Fender ToneMaster head for service. Basically needs caps, etc….
I’d like to see that video. I’m considering the same with mine.
Lyle, I'm perplexed - every amp I've ever owned has the speaker mounted to the baffle with 4 screws, yet the basket has 8 holes. Do the speaker manufacturers intend their products to be mounted with 8 screws? if not then why are there 4 extra holes in the speaker? The only reason I can think for the extra holes is to allow more flexibility in positioning the wire connection tab. What do you think?
Fender twins use all 8 holes
8:05 - who doesn't love a bit of "full wrist"?
You didn't mention speaker break in. I know that makes a ton of difference. Also, what do you think of putting a 125 watt speaker in a 18 watt amp? Will it have the ump to get the speaker loosened up?
Speaker break in is over hyped IME. They change but not that drastically.
I wouldn’t choose a 125W speaker for this amp. But I wasn’t asked.
@@PsionicAudio I do not agree. When I put a new cannabis rex eminence in my BJ, I didn't like the sound at all. The sound was not good, fizzy and boxy, with no bass. And after several weeks, the sound became wonderful. It all depends on the speaker. Cannabis rex takes a long time to break in, for example.
@@PsionicAudio Speaker break in is absolutely a thing.
Here's an amp that actually needs a standby switch and doesn't have one. Lol Fender, you put a standby switch in shiploads of amps that should not have one and then on the odd amp that does actually need one you don't bother omg lol. My MkIV series 2 blew a tube within weeks and fried the board. Good job Fender, you also know they run too hot and still haven't fixed the problem even after having another attempt in the MkIV series 2.
It doesn’t need a standby.
So would a evm speaker be not ideal in an amp like this? They’re rated crazy high, aren’t they?
I’m no expert but the new speaker in its current setup isn’t my favorite. In the name of science it will be interesting how it sounds with the amp wrapped up. Anyway always enjoy your approach.
What's another good speaker for the Jr.?
Swamp Thang
I like a celestion .green back .
Greenbacks are great in Blues Jrs, Swamp Thangs are a bit modern for my preference in a clean Fender amp. Both are absolutely amazing speakers though, they just do very different things
That is the Dilemma. There's no place to demo speakers.
I tried 4 or 5 different speakers in my Blues Jr.
My two faves are a Weber Blue Dog Alnico 30 watt speaker with the bell cover removed. It will fit just barely.
Or the WGS ET65 speaker which is a Creamback clone.
The Creamback clone is what I've liked best for live gigs. The Blue Alnico is best for recording.
Are the threaded fasteners for holding the speaker to the baffle board actual T-nuts with the flanges inbetween the front of the baffle and the speaker cloth?? If they are, kudos to Fender for doing it that way. But, if the inserts are merely threaded into the particle board baffle, then 😖😖😖 #@%&!! .....and regardless I would prefer to see 8 bolts rather than just 4 (even for a lightweight Neo-mag speaker, but especially if the speaker has a large heavy magnet). Not to mention that Torx-head bolts would be easier to use than Philips heads, easier to remove and reinstall/tighten without slipping or stripping.
I use JIS bits and screwdrivers instead of Philips. This reduces the inherent mangling that the Philips standard is designed with...
Noticed when checking speaker screw tightness on Fender DR, that there is a substance like fingernail polish on each screw...?
Is this a warranty trick...?
Couldn't believe how many loose screws/nuts there were...!!!
Thanks for that video that pointed out these things😉😎👍
😎👍
It's supposed to keep them from vibrating loose. You're very welcome!
@@PsionicAudio
I see...thanks...
However...
If they tightened them enough...they wouldn't need to put the fingernail polish on them to begin with...?
😉😎👍
I have a Blues Junior Mark IV... what resistor value should I use to "fix" the bias? The same value as the Mark III? Love your videos by the way. Thanks!
Not sure as I’ve heard reports of some fixed bias IVs and some cathode bias IVs, though I have not had any cathode bias ones come in. If it’s fixed bias, yes, 68K across R51.
@@PsionicAudio Awesome. Thank you so much!
@@PsionicAudio I thought you'd put an 82K across R51? Anyhow probably isn't all that different in the end.
The Texas Heat was my favorite in the Blues Jr. and came highly recommended at the time I owned one.
It had way more bass than the Neo demonstrated here. I wonder if the owner purchased it by mistake or something.
Have a Texas Heat on the shelf waiting to go into my BJ. Do you think the amp has enough power to drive the 150 watt Eminence? Was it to your liking and why?
Appreciate any info you can give, and I would answer any ?? you may have too.
@@averagegearreviews4109 I've had a Texas Heat in my Blues Jr for a few years. It drives it just fine. Plenty of lows. You won't get speaker break-up for sure but i rely on pre-amp distortion. Compared to Blues Jrs I hear on You Tube, I think mine is cleaner. But the amp is heavier than any OEM speaker.
@@genebrenner855 Good Morning, that's a fine point about speaker break-up. I too use pre-amp and pedals. I did some common mods to a TS-9 and it makes that amp sing.
Thanks again and enjoy your day!
foot lbs on the drill
Hi Lyle. What speaker would you recommend for the B Jr? I have similar amp with a seventy 80. Crapola.
Anything but the 70/80. I put an eminence swamp Thang in mine, sounds excellent
Eminence Legend is a great speaker for this amp.
Good luck choosing a speaker it's kind of a One-Shot deal. You can ask that question and get a hundred different answers. there is no place to demo them that's the problem.
@@stringlocker , yeah your right! Everything else in life you can demo first and decide, guitars, amps, cars and clothing. Hard to pull the plug for $150 -$300 not having an idea.
@@kmichaelp4508 You would hope the amp companies would do that research for us but they don't they put the cheapest thing they can find in there. Boutique amp companies do the research. I guess we're a little bit to blame are we ever satisfied.
Question: Is swapping the speaker on a Marshall DSL20CR something that a layman can safely do or would I need to get a tech to do it?
You can do it. Make sure it's the proper ohms and wattage.
@@dangitdan9938 Yeah I understand the principles, just need to make sure that I'm not going to be electrocuted. Now just need to decide if a Greenback or a Creamback is the way to go. (I think it's the Greenback)
You won't get zapped changing a speaker. Greenbacks don't like being in open-backed 1x12 combos. Creamback 65 will kill it in that context.
@@09philj I second the cream back. 🤘 I put one in my origin 20 and loved it.
@@PsionicAudio I see. What would generally be the downsides of putting a Greenback into a little 1x12?, out of interest?
That's the problem choosing a new replacement speaker there's no place to demo different speakers.
EL84 amps are pigs on tubes .I have owned at least an half dozen el84 amps all at a same time & all of them had the original el84's fail & had to be replaced within one year .
Place the amp *designers*, not the entire category of "EL84 amps". The amps are invariably designed to push the tubes way harder than they can take for any length of time, especially today's modern Russian and Chinese-made tubes.
I blame the designers assuming they can bias is crazy hot.
@@davidfuller581 , They might have gotten away with this kind of circuit design and hot biasing 60 years ago when you could go down to the local tv/radio repair shop or perhaps even the drugstore and buy some Mullard or Telefunken EL84'S every 6 months or as needed, but nowadays with Russian and Chinese tubes and ultra high wall voltages, they need to rethink their designs.
? I have the Monoprice/Harley Benton State Right 15w amp. It is cool biased, but the gain is extremely sensitive and goes very gainy after increasing the gain nob to 2, it's like the master volume. Because at 1, and you turn the amp up with the volume, it is pretty low in volume, but nice and clean. Once you get it to 2, you are already in crunch. How can I affordablely lower that gain and clean it up going past 2? Oh. It has the original speaker. The Celestion Seventy 80 12in.
Correcting the problems in those amps costs way more than the amps do.
@@PsionicAudio true, but it would be worth it in the long run wouldn't it? Having an amp that I already paid off and improving it little by little to get a quality sounding amp. Yes, it will only be worth what it is worth, but the end result is what I want. Since I will not sale it because its not worth much.
Not in this case IME. You'd be better off buying an amp you already like the sound of. The HB/MPs are landfill destined by design.
@@PsionicAudio thank you for your honesty. It does help some decisions I am making for sure.