# Traynor YBA-1 updating



## stormbringer (Aug 27, 2014)

Traynor YBA-1 with updated power input (3-prong power cord, no ground switch, no death cap), newly adjustable fixed bias, new filter caps, and greatly improved grounding scheme. Since taking this photo, I added a shielded wire from input to V1, bridged the inputs, isolated the input jacks from chassis, and tied the grounds to the appropriate point in the power supply (rather than to random spots on the chassis). Sounds KILLER.


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## Frenchy99 (Oct 15, 2016)

Cool... you made those small boards to replace the top can filter caps ? is that your design or it that something available online ?


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## stormbringer (Aug 27, 2014)

Frenchy99 said:


> Cool... you made those small boards to replace the top can filter caps ? is that your design or it that something available online ?


Yes, those are my own PCBs. The two caps can be in parallel or separated by a dropping resistor to supply two nodes. The longer board holds an additional dropping resistor. 

For the YBA-1, I use 500V caps for the first two boards (to supply plates and screens of the output tubes), and 450V caps elsewhere.


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## Frenchy99 (Oct 15, 2016)

stormbringer said:


> Yes, those are my own PCBs. The two caps can be in parallel or separated by a dropping resistor to supply two nodes. The longer board holds an additional dropping resistor.
> 
> For the YBA-1, I use 500V caps for the first two boards (to supply plates and screens of the output tubes), and 450V caps elsewhere.


Im doing cap jobs for most of my amps lately and found new 50uf-600 volts axial caps so only 1 cap to replace 2 of the old 350uf400volts ones in series. Putting in additional strips to hold them secure inside and leaving the existing can caps for aesthetics. 

Nice clean work you've done there !


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## stormbringer (Aug 27, 2014)

This YBA-1 had the dynamite-stick axial e-caps inside the chassis rather than the can caps. Curiously, those axial e-caps were rated at 450V, and the B+ was a bit higher than 450V with my 120Vac mains power.


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## Frenchy99 (Oct 15, 2016)

Ok. You have a 1975-76 model. 

The YBA-1 has many different revision.


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## stormbringer (Aug 27, 2014)

Frenchy99 said:


> Ok. You have a 1975-76 model.
> 
> The YBA-1 has many different revision.


It's the one with three gain stages, a T-filter, and a plate-driven tone stack. I used to call this the 'Mark II' until I realized that the Mark II is the 80W one...


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## stormbringer (Aug 27, 2014)

I kinda went crazy with Traynor amps lately...


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## Frenchy99 (Oct 15, 2016)

stormbringer said:


> I kinda went crazy with Traynor amps lately...


Welcome to the club !!!


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## Ti-Ron (Mar 21, 2007)

Nice looking job!!!


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## stormbringer (Aug 27, 2014)

Totally revised the preamp...


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## Mikev7305 (Jan 6, 2020)

Please enlighten me about those new switches


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## stormbringer (Aug 27, 2014)

Mikev7305 said:


> Please enlighten me about those new switches


They are miniature switches.


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## stormbringer (Aug 27, 2014)

Mikev7305 said:


> Please enlighten me about those new switches


ok, sorry 'bout that.
The left-most switch is a 'bite' switch. Like a bright switch but better.
The right-most switch is a 'punch' switch. Kinda like a Friedman S switch.
There are two switches on the back panel for FAT and Era (gain switch; not clipping)

Gain II is now a master volume.
Inputs are low- and high-sensitivity inputs, like a 2204. Sort of...


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## stormbringer (Aug 27, 2014)

Today, I turned the other Traynor YBA-1 into a Soldano-SLO-based thing. Single channel, one-trick pony at the moment. But it does that one trick very well.

There weren't enough preamp gain stages in the stock amp for the full SLO preamp, even after omitting the effects loop. So I got a little creative. Any guesses?


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## Markus 1 (Feb 1, 2019)

I'd guess you inserted a gain stage either mosfet or a tube screamer circuit

Wild guess because that is what I may have done


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## stormbringer (Aug 27, 2014)

Markus 1 said:


> I'd guess you inserted a gain stage either mosfet or a tube screamer circuit
> 
> Wild guess because that is what I may have done


Correct!
I built a source-follower using the LND150 and some other components to take the place of the tube cathode follower.


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## Markus 1 (Feb 1, 2019)

Love it!!!!


May I ask do you have a schematic or source?


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## stormbringer (Aug 27, 2014)

I found a schematic for a FET version of the JCM800 by online user KMG (ssguitar.com) and designed my own PCB around the source follower in that schematic. I have a whole stack of PCBs now... (more than I'll ever use)


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## Markus 1 (Feb 1, 2019)

Interesting
I'm looking at designing over- built (robust, thick, wide trace) PCB circuits soon myself for an amp design


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## stormbringer (Aug 27, 2014)

Markus 1 said:


> Interesting
> I'm looking at designing over- built (robust, thick, wide trace) PCB circuits soon myself for an amp design


I follow thickness and spacing guidelines for the PCBs; I don't make the traces unnecessarily wide, because it leads to other issues (e.g., spacing). 

I wanted to install this PCB right onto the YBA-1 eyelet board. So the mounting holes are 1.75" apart, just like the eyelets. And I added a shield plane on the bottom of the PCB that I attached to the chassis, with the hope that it would help shield the source follower circuit from stuff on the eyelet board below.


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## Markus 1 (Feb 1, 2019)

Very cool
Thoughtful design


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