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My '71 Traynore YBA-1 has been Plexified

Riffraff

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Joined
Jun 16, 2002
Messages
167
My parts order was delayed a little over a week due to the snow storm backing up USPS shipments but the parts came last week and I couldn’t wait to get into it. I went out in my barn at 5 am Saturday morning to do the mods to my YBA-1. It was 25 deg and I froze my ass off but it was worth it.

Here is the before picture:



And the after (picture taken before I added the cathode bypass cap and changed the feedback resistor):



The work done:

I installed long overdue new filter caps.

I removed the 470k linear volume controls and put new 1 meg logarithmic volume pots in their place. I used a switching pull pot for the bright channel to control some preamp changes.

I swapped the 100k mixing resistors replaced with 220k. Antique Electronic Supply was out of 270k and naturally the local Radio Shack didn’t have them either so I used the closest value I had.

I replaced a .1 cap in the tone stack with a Mallory .022, replaced the slope resistor with a 33k and swapped out the 320pf cap with 500pf silver mica. That makes the tone controls a lot more useful.

I connected a 2.2k resistor and a 22uf cap to the switch on the pull pot which connects parallel to V1B's 1.5k cathode resistor when pulled. That provides a nice gain bump when engaged and is at stock value when off.

Lastly I replaced the 100K feedback resistor changed to 47k.

Everything is working perfectly. The volume controls are no longer on/off controls and the amp has definitely shifted to the Marshall camp in the tone department.

Here’s my frozen fingers test clip through a V30 loaded 212 cab.

Les Paul straight in, no pedals at all.

 
Last edited:

renderit

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Jan 19, 2009
Messages
10,951
Dang! Those caps look like sumpin' ain't supposed to be in there! I hopes you was careful in 'da disposal of those. Don't be hittin' dem wit 'da rock!
 

MapleFlame

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Jul 3, 2005
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14,044
I really like the tone of this amp. Very versatile and great note separation. Grind is great too.
 

Riffraff

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Jun 16, 2002
Messages
167
It gets SICK with a clean set SD-1 slamming the front end. Loads of CHUNK there.

 

TM1

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Jun 27, 2003
Messages
8,349
Did you add a choke to the power supply? Makes a big difference in the way the B+ operates in those amps and also gets rid of the underlying slight hum that Traynor's have(basically any amp without a choke will have that. It goes between the 1st & 2nd stage of the filtering.
 

Riffraff

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Jun 16, 2002
Messages
167
No I didn't do the choke mod.....................yet. :D
It does get a bit addicting doesn't it?
 

TM1

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Jun 27, 2003
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8,349
No I didn't do the choke mod.....................yet. :D
It does get a bit addicting doesn't it?

Yes, it certainly does! I've played Traynor's on & off since 1971. I own two Guitar Mate's, Actually one is a "Studio Mate-YGM-4". Same chassis but has 4-8" speakers. Great little 25 watt amps. They're fun and easy to work on!
 

Riffraff

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Joined
Jun 16, 2002
Messages
167
I know a guy that has a Studio-Mate. It looks new and is still full of it's original Philips labeled Mullards.
 

TM1

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Jun 27, 2003
Messages
8,349
I know a guy that has a Studio-Mate. It looks new and is still full of it's original Philips labeled Mullards.

Since Canada is part of the Commonwealth, they were using many of the same makes of parts as their U.K. brothers. Phillips imported the "mustard caps" from the Czech Republic that were made by Iskra. Phillips was a massive electronics supplier for all the member nations of the Commonwealth, so not at all uncommon to see similar parts common to many amp makers. I know my first CD player back in the late `80's was a Phillips made in Belgium. It certainly was on a better level than most newer Chinese rubbish units. I got probably 15 years use out of it..
 
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