I just acquired one of these in a trade. It needs adjustable bias and I will also swap the audios for linear. Thanks for the tips, Lyle. You and Uncle Doug are tops in this industry!
seems like a lot of wha you read in the interwebs, says bias a push pull amp to up to 70% dissipation. I, have never found a Fender amp that sounds it's best biased with that much current. Around 50-55% always seems to sound best to my ears. Thanks for the video
I have a 5E8A built from a Weber kit, with many component upgrades and a bias pot. Sounds great! Interesting that mine has a big difference between the Normal and Bright channels.
You don’t need to bridge the channels on the 5E8-A like in the Bassman, etc., the channel inputs use both triodes of the corresponding preamp tube, rather than just one. You can use a Y cord into the #1 input of each channel and have a blast with these amps.
Not quite. Input 1 of each channel uses two triodes if nothing is plugged into Input 2 of that channel. Input 2 only uses one triode, hence lower gain. If you use a Y cable into both inputs of a single channel it’s the same thing as using just Input 1 of that channel.
Thank you for the tutorial on the 5E8A. I built one after a 5E3 and always felt something was wrong. I had it to 2 different techs, neither found the simple things you did. I knew about the 12ax7 swap out and that helps either my playing style. I’m going to linear pots as soon as soon as they come. Oddly Stewmac doesn’t even sell them. Question - given that the kit came with audio pots for treble and bass as well, does it make sense to change them all to linear? I read the science of perception etc but just asking your opinion.
I was thinking of buying a MOJOTONE twin reverb kit. I have a TR `79 SF that is rusty and the plate has mold, I was thinking of rebuilding it completely but doing it black face. So I think I will be safe with that kit.
Don't use Mojotone. Check out the Hoffman Amps version. I used that on my AB763 build. Also the Mojotone 18 watt TMB is just a bad amp design. Super noisy. I made the mistake of building that. Ended up ripping it out and rebuilding based on the Trinity designs.
I am getting ready to build this same Mojo kit. I would like to make the Bias adjustable. Can I use a Fender style chassis mount 10K bias pot in series with a 12K 1W resistor in place of the 56K resistor to achieve a good useable bias range? Can I go from the diode to one leg of the pot, then the wiper with 12K resistor in series to ground? Leave the other pot leg unused? Thanks so much in advance; I love this video series!!!
You played it and it has a good sound. Using 12ax7 to drive 6l6 is a very poor choose . Found the lack of screen grid resistor and running them at a voltage above the plates note worthy . As we see here the use of prudent design in the operation and choose of tube types may well not have provided the sound they where looking for. However it does appear to work in that amp .
Well it’s a cathodyne PI so a 12AX7 is “fine” there - it’s an inherently flawed circuit so there isn’t really a Best Practice for it. And lots of Marshalls and Voxes do great with a 12AX7 LTP - there’s “proper” sound design and there’s what sounds interesting to our ears. Guitar amps sound awful built to Hi Fi specs.
@@PsionicAudio Well cathodynes work better with more current thru them a 6cg7 , 6sn7. even 12au7 is a better choose . Given that they used so few types of tubes ay7 and ax7 and power tubes I see the design "criteria" Fender used . The purpose of a Guitar amp is quit different than a Hi-Fi amp . Thou they both may use the same tubes Hi-Fi tries it best to not change the signal just louder. The Guitar amp is as you have so finely have shown is in fact of the sound shaped by the player and does not have the same flavorless design . Having said that I prefer that the small signal tubes do all the color and the power amp section just amplifies . A view that is not that of most famous players . Enjoyable video.
335 sounds great through this amp😎👍 Hope someday you get to try out a Revstar RSS02T with the P90's and focus control...Montgomery octaves sound so good😃😎👍❤🖖
Would the 1meg Linear pots hold true for an AB763 circuit? I've been fighting with this for a while now. I've verified everything and the amp sounds great but the volume doesn't start to come up until you hit about 2 1/2 on the dial. I know that Vox's call for Audio taper due to circuit design, but I can't find a good answer on the Fender AB763 circuit.
AB673 should have 30% taper volumes and trebles. J taper. Sounds like you ran into the CTS 1MA problem where there is nothing nothing nothing ON. No gradual taper below 9:00.
I built 5E3 (deluxe) and a tweed princeton - 5E3 is my fav, after watching this video the Princeton is in 3rd place. All amazing tone amps. I’m floored that I have this quality of sound in amps i built myself.
100% on the bias. Totally different type of bias, cathode biased on the 5E3, fixed bias on this. You can go a little above 100%, depending on the tubes. JJ 6V6s are rated at 14 watts so there's more wiggle room. I've got a pair of ANOS Ken Rads biased at around 92% and they sound awesome.
The 5E3 uses a different method of dealing with mixing two volume controls together. They wire the volume pots bass-ackwards. In other words, input to the wiper and output from the CW lug. I think you'll have better control using audio taper pots. If you want decent longevity in your output tubes, biasing around 50% of rated power is a good choice. If you have issues with crossover distortion, 70% will cure that. A 5E3 is push-pull so biasing near 100% doesn't accomplish anything other than shortening the life of the output tubes.
@@retread1083, biasing at 100% would likely cause significant power-supply drop or sag and also saturate the heck out of the output transformer, unless they're both a bit over-sized/over-spec'd (for a 5E3 clone).
A mixture of good and bad advice here. You want J or A taper volumes in a 5E3. The bias should be set to between 12-14W at idle. That’s 100% or slightly over. The bias resistors come in standard values and you can’t get too precise. So long as it’s at least 12W and no more than 14W, you’re good. This is a cathode bias amp. Bias it at 50% and you’ll have low output with nasty crossover distortion and your B+ will skyrocket and probably kill 6V6s.
Howdy all....I have a question.....I've always been interested in owning a fender blues Jr. I always notice though when I look them up on GC there are always a lot of used blues jr amps for sale. I guess my question is why are there always so many of these amps on the used market. From a technicians perspective are they not put together well with lots of issues, or is it a one trick pony that people eventually get tired of. Any input or thoughts would really be appreciated....thanks johnny from Albuquerque NM.
Hey there.....thanks for the reply. I watched the videos and I understand your point. I wonder why their engineers dont figure this stuff out before the finalize a design....thank you for the info.
More versatile than I would have expected. Pleasantly surprised by how much natural overdrive can be had.
I just acquired one of these in a trade. It needs adjustable bias and I will also swap the audios for linear. Thanks for the tips, Lyle. You and Uncle Doug are tops in this industry!
I built this circuit about 15 years ago. It’s a great pedal platform amp too!
This amp sounded WAYYYY better than I was expecting…really some fantastic classic rock recording sounds in there.
The Radial A/B/Y boxes are amazing. I have basic non-LED model and it’s worth every penny.
They do the job they were designed to do ... I have 2 going on 3 soon ...
Interesting, I have a low power tweed twin that I built back in 2009, still gig with it now! Think I'll try some linear volume pots in it.
Hope you and yours had a nice holiday weekend from your friendly neighbourhood Canuck! 🇨🇦
I sent a comment on your 66 Gemini video regarding standby switch wiring.
Your channel got recommended on Phil McKnight's live stream on Friday!
Yeah, that was very cool of him. I left a sincere thanks.
seems like a lot of wha you read in the interwebs, says bias a push pull amp to up to 70% dissipation. I, have never found a Fender amp that sounds it's best biased with that much current. Around 50-55% always seems to sound best to my ears. Thanks for the video
I have a 5E8A built from a Weber kit, with many component upgrades and a bias pot. Sounds great! Interesting that mine has a big difference between the Normal and Bright channels.
You don’t need to bridge the channels on the 5E8-A like in the Bassman, etc., the channel inputs use both triodes of the corresponding preamp tube, rather than just one. You can use a Y cord into the #1 input of each channel and have a blast with these amps.
Not quite. Input 1 of each channel uses two triodes if nothing is plugged into Input 2 of that channel.
Input 2 only uses one triode, hence lower gain.
If you use a Y cable into both inputs of a single channel it’s the same thing as using just Input 1 of that channel.
@@PsionicAudio Right, I meant a y cable into each #1 input. Sorry!
Hi if the plate voltage on the tubes is around 450v or less you could also use thje tung sol 6l6 (non-gc).
Nice!! For the price compared to Fender custom shop ???????
You can build a much better amp from the kit than the Fender reissue.
Yeah, though it depends on how well it’s built.
This builder did a better job than the FCS does. Sadly the Mojotone instructions hampered his efforts.
Thank you for the tutorial on the 5E8A. I built one after a 5E3 and always felt something was wrong. I had it to 2 different techs, neither found the simple things you did. I knew about the 12ax7 swap out and that helps either my playing style. I’m going to linear pots as soon as soon as they come. Oddly Stewmac doesn’t even sell them. Question - given that the kit came with audio pots for treble and bass as well, does it make sense to change them all to linear? I read the science of perception etc but just asking your opinion.
Treble and Bass pots were originally linear on the 5E8A as well. But see what your ears like. Noon on a linear is about 2:30 on audio.
I was thinking of buying a MOJOTONE twin reverb kit. I have a TR `79 SF that is rusty and the plate has mold, I was thinking of rebuilding it completely but doing it black face. So I think I will be safe with that kit.
Don't use Mojotone. Check out the Hoffman Amps version. I used that on my AB763 build. Also the Mojotone 18 watt TMB is just a bad amp design. Super noisy. I made the mistake of building that. Ended up ripping it out and rebuilding based on the Trinity designs.
Very nice work Sir.
I am getting ready to build this same Mojo kit. I would like to make the Bias adjustable. Can I use a Fender style chassis mount 10K bias pot in series with a 12K 1W resistor in place of the 56K resistor to achieve a good useable bias range? Can I go from the diode to one leg of the pot, then the wiper with 12K resistor in series to ground? Leave the other pot leg unused? Thanks so much in advance; I love this video series!!!
Thanks. Yes, but 12K is likely too small. Start with 47K, might go down to 39K or 33K. Don’t leave the “extra” lug disconnected - tie it to the wiper.
@@PsionicAudio Thank you so much!
You played it and it has a good sound. Using 12ax7 to drive 6l6 is a very poor choose . Found the lack of screen grid resistor and running them at a voltage above the plates note worthy . As we see here the use of prudent design in the operation and choose of tube types may well not have provided the sound they where looking for. However it does appear to work in that amp .
Well it’s a cathodyne PI so a 12AX7 is “fine” there - it’s an inherently flawed circuit so there isn’t really a Best Practice for it. And lots of Marshalls and Voxes do great with a 12AX7 LTP - there’s “proper” sound design and there’s what sounds interesting to our ears.
Guitar amps sound awful built to Hi Fi specs.
@@PsionicAudio Well cathodynes work better with more current thru them a 6cg7 , 6sn7. even 12au7 is a better choose . Given that they used so few types of tubes ay7 and ax7 and power tubes I see the design "criteria" Fender used . The purpose of a Guitar amp is quit different than a Hi-Fi amp . Thou they both may use the same tubes Hi-Fi tries it best to not change the signal just louder. The Guitar amp is as you have so finely have shown is in fact of the sound shaped by the player and does not have the same flavorless design . Having said that I prefer that the small signal tubes do all the color and the power amp section just amplifies . A view that is not that of most famous players . Enjoyable video.
335 sounds great through this amp😎👍
Hope someday you get to try out a Revstar RSS02T with the P90's and focus control...Montgomery octaves sound so good😃😎👍❤🖖
One has been on order for nine months… ;)
@@PsionicAudio
Had to wait 4 months for it🙄
However...can tell you that the wait will be worth it.
😉👍
Would the 1meg Linear pots hold true for an AB763 circuit? I've been fighting with this for a while now. I've verified everything and the amp sounds great but the volume doesn't start to come up until you hit about 2 1/2 on the dial. I know that Vox's call for Audio taper due to circuit design, but I can't find a good answer on the Fender AB763 circuit.
AB673 should have 30% taper volumes and trebles. J taper.
Sounds like you ran into the CTS 1MA problem where there is nothing nothing nothing ON. No gradual taper below 9:00.
@@PsionicAudio Yes Sir that's exactly it. Once it's on, it's on. It basically acts like a Gain from that point. Thank you for the info my friend!
If I was going to do a tweed Twin, I’d go 5F8 so you get the LTP phase inverter.
Do you have any kits you would suggest? I actually built a Mojotone kit before and would love to do another someday…
I built 5E3 (deluxe) and a tweed princeton - 5E3 is my fav, after watching this video the Princeton is in 3rd place. All amazing tone amps. I’m floored that I have this quality of sound in amps i built myself.
Is there a source for the correct pot?
Lyle, would you recommend linear taper volume pots in a 5E3 clone as well? Also what is a good bias percentage to shoot for in a 5E3.
100% on the bias. Totally different type of bias, cathode biased on the 5E3, fixed bias on this. You can go a little above 100%, depending on the tubes. JJ 6V6s are rated at 14 watts so there's more wiggle room. I've got a pair of ANOS Ken Rads biased at around 92% and they sound awesome.
The 5E3 uses a different method of dealing with mixing two volume controls together. They wire the volume pots bass-ackwards. In other words, input to the wiper and output from the CW lug. I think you'll have better control using audio taper pots. If you want decent longevity in your output tubes, biasing around 50% of rated power is a good choice. If you have issues with crossover distortion, 70% will cure that. A 5E3 is push-pull so biasing near 100% doesn't accomplish anything other than shortening the life of the output tubes.
Try the mod that separates the channels on the 5e3 , with the 220k mixer resistors, the volumes will be more usable .
@@retread1083, biasing at 100% would likely cause significant power-supply drop or sag and also saturate the heck out of the output transformer, unless they're both a bit over-sized/over-spec'd (for a 5E3 clone).
A mixture of good and bad advice here.
You want J or A taper volumes in a 5E3.
The bias should be set to between 12-14W at idle. That’s 100% or slightly over. The bias resistors come in standard values and you can’t get too precise. So long as it’s at least 12W and no more than 14W, you’re good.
This is a cathode bias amp. Bias it at 50% and you’ll have low output with nasty crossover distortion and your B+ will skyrocket and probably kill 6V6s.
Howdy all....I have a question.....I've always been interested in owning a fender blues Jr. I always notice though when I look them up on GC there are always a lot of used blues jr amps for sale. I guess my question is why are there always so many of these amps on the used market. From a technicians perspective are they not put together well with lots of issues, or is it a one trick pony that people eventually get tired of. Any input or thoughts would really be appreciated....thanks johnny from Albuquerque NM.
Johnny, go to my Playlists. Click on Blues & Hot Rods. Tons of videos on the Blues Junior.
Or save time - avoid at all costs.
Hey there.....thanks for the reply. I watched the videos and I understand your point. I wonder why their engineers dont figure this stuff out before the finalize a design....thank you for the info.
Anyone else tried linear pots? Any use?
What is a good low microphonics 12ay7 these days?
If you find one let us know, even the vintage ones ring like a bell
These days? The one in stock that you can actually get. Tube Depot will sort for low noise and microphonics for $4 extra.
Does this have the 12ay7's in the amp?
ok 12:00
I have a 1995 american Fender Blues Deluxe but its cream colored with ox blood grill cloth are these the same amps
No, very different amps despite any cosmetic similarity.