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NAD: Traynor YBA-3 Custom Special

Discussion in 'Amps and Cabs [BG]' started by Patrice B, Apr 18, 2021.

  1. Hello all,

    Following this thread Traynor YBA-3 impedance rating and info (for posterity) , I’ve decided to open a new thread for this latest acquisition/resto.

    Couldn’t help myself, wanted one for a while and I saw one in a local guitar shop being there for almost three years. I didn’t really got a deal but anyway!

    It was announced as being a 1970 but upon email exchange with Yorkville/Traynor, it’s a 1969. Date codes on the cans indicates DEC 09 too.

    First tests showed no hum, scratchy switches and annoying crackling/popping.
    Three prongs conversion already done, good.

    After two weeks sitting gathering dust on my bench, I’ve completed all what’s needed yesterday evening:

    - all filter caps were replaced with two times [email protected] in series, reusing the original 100k’s balancing resistors. Under the hood with some old clamps and zip ties;

    - Illinois [email protected] filtering for the preamp/PI was replaced with a Xicon 100uf. The Illinois was probably there since the 90´s, so 30 years;

    - the two 8uf bias caps got replaced;

    - the two 250uf’s at V1 and V2 got swapped each for a 200uf paralleled with a 47uf. Hard to find value nowadays...;

    - Deoxited all switches and pots;

    - crackling/popping was cured by swapping V1 with another 12AX7 in my collection. Weird, as I tried previously two swap around the three original 12AX7’s but the problem remained. Probably that the two other ones don’t exhibit their noise in other positions (V2 and V3 PI);

    - undocumented and short lived 1 Meg PI balance pot appears to be seized and stuck at the middle (500k on each side). Not sure, but it could also be that someone put a little circlip to block it... Anyway, I won’t bother. Not looking for high fidelity here...;

    - precedent tech added a 10k bias pot: it was set at 85-90 ma for each pair! Yikes, talk about hot bias, almost 100 percent dissipation!! Got it dialed back at 53-55 for each pair, 60 percent with a plate voltage of 550vdc. Those JJ’s E34L did had a hard life but still test at 80-85 percent on my tube tester. Tough tubes!

    I’m tinkering about the addition of a master volume as shown on the later version but I will try it as is for now.

    Dead quiet, powerful and it was a breeze to bring in it up to specs technically wise. One evening of work, thanks Mr Traynor for the simple layout!

    It’ll go back in its cabinet today and will be paired with my Ampeg SVT-210AV bass cab. The SVT-210AV was paired with my V4 but someone local built me a 2x12 cab for the two Basslite’s S2012 remaining from my YGL-3 combo project.

    Last edited: Apr 18, 2021
    westrock, xn34, BeauZooka and 3 others like this.
  2. Work done, not that pretty but nobody will see it upload_2021-4-18_11-7-19.gif



    Appears to be a circlip on the PI balance pot, what do you think?


    I will post some pics once back in its cab.

    **Ah, the fan: the original is loud. I’ve removed the little cap and put sewing machine oil, a bit better. Got two replacement models from Addison but they are louder than the original. Not sure I’ll connect back the fan as my Ampeg V4 don’t have one.

    I could also put a 12 inches computer fan and run it with an adjustable DC wall wart (at 4.5 or 6v) from the convenience outlet, like I did on the V4.
    westrock, Ellery and Rockbobmel like this.
  3. i usually throw a 220uf in place of 250uf, although even as low as 47uf likely wouldn't negatively effect the tone
    Patrice B likes this.
  4. Good on ya, I got one a month ago, they're pretty sweet
    Patrice B likes this.
  5. Ah, not that important to have the exact value... Yes, 220uf is more common. Too late...
  6. Sweet beast! Like the utilitarian but classy look, to my eyes!

    Easy to work inside, big trannys, huge sound. Traynor is our Fender here!
    pie_man_25 likes this.
  7. I see you have an Eico 460; that was my first scope, and used it until I bought my Hitachi V1065 in the 1980's. Brings back memories.
    Patrice B likes this.
  8. Computer 12 VDC running at 4.5, plugged through universal DC wall wart. There is an off switch if I need for recording.

    Yeah, not recapped but working! Now to learn how to use it! I also have a Telequipment tubed one.
    Ellery likes this.
  9. groovaholic

    groovaholic The louder the better. Supporting Member

    Sep 19, 2004
    Mount Prospect, IL
    You know, there are those who would argue that your amp will sound better if you bias it with a tube-based oscilloscope... ;)
    Patrice B and Engle like this.
  10. Biasing at 55-60 percent. Longer tube life and not sure I could hear the difference...

    It’s not the first time I hear about that biasing with an o’scope is the best way but my ears are not what they had been, so... ;)
  11. Hmm! Someone noticed in another forum that the three prong wiring is not right (white to fuse).

    I’ll have to open it again to correct this (already under a pile of three other speakers/amps/devices in the home studio).
  12. xn34


    Dec 17, 2020
    I am sooooooo Jelly!!!! I'd love to have one of those!
    Patrice B likes this.
  13. Hawkbone

    Hawkbone Supporting Member

    Mar 23, 2009
    Nice! I just scored a YBA-4 so guess a NAD thread is in order.
    Patrice B likes this.
  14. I've owned 9 or 10 YBA-3 Custom Special amps over the past 50+ years and in my opinion the early pre master volume versions sound the best. If I was to buy one today, it would be identical to the one in Patrice's photo above in post # 9. I bought my first one in 1969 used along with a YC-810 Big B cab.

    Patrice B likes this.
  15. Ampslut


    May 15, 2017
    I had that amp with a single 8x10 cab back in the early 70's. It had a tone that would cut through a marching band.
    Patrice B and Hawkbone like this.
  16. Comparing with my V4 (non B) no master volume, it’s different even if they are « 100 watts » amps. I hear that a good healthy V4B with 7027 is around [email protected] percent distortion (Bass Mag Gear review). I think the YBA-3 could reach a tad higher but at unknown to me distorsion figure. Anyway, basement playing here so girlfriend and neighbors (and my ears) wouldn’t be happy if I try them at max.

    The Ampeg has... the Ampeg sound! And the Traynor... the Traynor sound ;)

    It’s fun to have several amps to practice and the YBA-3 was on my holy grail list (as was the V4 too). No, YBA3-A or the SVT weren’t on my holy grail list: too much power for a little home studio!
  17. Jeff Scott

    Jeff Scott Rickenbacker guru..........

    Apr 11, 2006
    My first bass amp was a YBA-3, bought new in 1974 (the model with the "bumpers"). Later on, in the early '80s I bought a used, similar era, YSR-1 for recording bass with. That amp I wish I still had.
    Patrice B likes this.
  18. Update:

    I’ve took the time to rewire correctly the three prongs AC: I’ve copied what’s inside my YVM-1 (had to correct it too back in 2019).

    Being in there, I swapped the four Shuguang Preferred Series from my YGL-3. The JJ’s ended in the YGL-3. A small mod to the bias feed had to be done: 56k and the already present 10k trimmer. Someone had put a 47k in serie with the 10k. Not enough range to bias the Shuguang colder...
  19. Interesting snippet from EL34world.com:

    « From Kevin O'Connors TUT3, Custom Special, chapter 14, 9 pages. (With Traynor's schematic and Kevin's 'improved' clone schematic and Kevin's full layout drawing, but no measurements on layout.);

    He writes that for the 160w (4xEL34) YBA-3 Custom Special Traynor used the Hammond 278CX which is a higher plate current version and higher heater current of the 278X already being used in the 80w YBA-1A. And Traynor used the stock Hammond 1650T 120w full bandwidth OT with a 1K9 aa. This stock OT had Hammond's usual dual winding secondary with 5 leads. Traynor had this simplified to 3 leads for 2 Z taps, so custom ordered.

    "The 1650T is just less than half the Z of the 165N, and in both cases, he also ordered his units without UL taps."

    My understanding is that the snipped green tap could be 4ohms. No way for me to measure though…

    Source: Traynor amp- OT Tranny Specs
  20. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    May 8, 2021

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