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What is the difference between the Traynor YBA-1 and Marshall JTM?

JTM fan

Member
I've heard the JTM and YBA are similar to tweed Bassman's.......

...I've also read that the YBA's has 4M pots.....normal marshall's have 1M pots.

How does this change the tonal response of the amp.......beyond that, how does the tone differ?
Will the YBA compare to the JTM?
 

cugel

Supporting Member
yes they are a similar circuit but i am pretty sure that the plat voltages on the yba are sig. higher than the other two. i have neer played a yba but i think the headroom is higher. it seems traynor wanted to improve reliablity etc and mayde some changes accordingly. but also keep in mind that the trannys are hammonds vs radio spares etc which is another, still the traynor is a killer amp
 

drewl

Member
Shhhh!
They are incredibly similiar, especially the early YBA's with a choke.
A little tweaking and you'll have an awesome amp.
 

daddyo

Guest
Not so fast - the United Nations has declared a moratorium on modding vintage Traynor amps. Sanctions could be imposed on violators.:nono
 

cugel

Supporting Member
there is a site velvet black i think where a guy details the mods he did and gives you clips try this http://kilback.net/Traynor_Tweaks_rev12_sk2007.pdf
traynors are a not so well kept secret in vintage amps such a piece of cake to work on you just open op the top and its all right there no need to remove a chassis for most stuff and the schematic is on the lid

clearly you will need to change the pots and the values of the tone stack
 

DGDGBD

Member
Actually the plate voltages are very similar on the YBA-1's (at least the 60's vintage that people compare to JTM-45). Mine is at about 410v to 420v. YBA-1 uses 4Meg vol pots. I think there were minor differences in the tone stack and mix resistors. YBA-1 uses a huge bright cap while JTM-45 uses 100 pf. JTM-45 use tube rectifier and KT-66 tubes into a 6K or 6.6K OT primary. Only the very earliest YBA-1's have the tube rectifier. They typically use 7027 or EL34 tubes into a 4K OT primary. SS rectifier YBA-1's put out 45 to 50 watts; stock JTM-45's put out something like 30 to 35 watts.
 

Thomas27

Member
If you have a quick looksie through the old JTM schems there's a few minor cap value differences and the afforementioned huge 4meg vol pots. Fiddle with the knobs enough and those traynors sound great, I wouldn't bother trying to mod it to Marshall specs, there's enough JTM sounds in there if you look. The traynor has a bit more of the bassman sparkly grind and of course we all know where the JTM comes from. That circuit's made a lot of different companies a lot of amps.
 

keto

Member
I'm not a tech but I recently had my tech do *minor, reversible* mods to my '77 YBA-1.

-4 meg pots mean when you roll up the volume it's INSTANTLY MIND NUMBINGLY LOUD AT '1'. Replacing with 1 meg gives it some semblance of roll up, but it still gets LOUD fast.
-he clipped a bright cap and inserted something or other in the circuit to tame a bit of brightness, the type of brightness that made the amp almost unbearable with both treble and presence at '0'
-he said that the schematic is a sort of hybrid of Marshall & Fender with Traynor's own spin added, elements of both are in there but neither is it a copy of either.

It's an ignorantly loud amp with a lot of clean headroom before crunch starts. I can stand my 50 watt Hiwatt (nearly) dimed in the basement, I couldn't handle the YBA-1 on '4' for more than 10 minutes - and my kid, who plays lead in a hard rock band, would run to his room when he saw me plugging it in....yes, THAT loud. So I recently got a Ho attenuator, and NOW I know what the amp sounds like run well up. It definitely isn't Marshall crunch/gain/power tube saturation exactly, but it's in the neighbourhood. Mine sounds a bit loose, needs a pedal to tighten up. I'm running EH 6CA7's in it for power section.

I recognize that my '77 might be a bit different than the earlier ones, just passing on my experience.
 

JTM fan

Member
I haven't modded mine yet......and I don't think I will.....

Although, the swapping of pots sounds like a good idea......not to mention I'm getting some sort of microphonic feedback through my Ch. 1 knobs??? If I flick the knob you can hear a *ping*.....some times it even feedsback until I tap or jiggle the knob. :confused:
 

johncarte

Member
there is a site velvet black i think where a guy details the mods he did and gives you clips try this http://kilback.net/Traynor_Tweaks_rev12_sk2007.pdf
traynors are a not so well kept secret in vintage amps such a piece of cake to work on you just open op the top and its all right there no need to remove a chassis for most stuff and the schematic is on the lid

clearly you will need to change the pots and the values of the tone stack
Yup...been here....
 


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