Traynor YBA 1 Plexi mods - Les Paul straight in

I did the work in my 25 deg work shop and then made this clip by recording my tone tests. Forgive the playing, My hands were so cold I could barely move my fingers and you can really hear that in the first part. LOL These are the mods I did:
Replaced volume controls with 1 Meg log type, replaced 100K mixer resistors with 220K (all I had, need 257k), replaced the slope resistor with 33k, replaced 320pf cap with 500pf, replaced .1 uf Mustard cap in the tone stack with Mallory .022uf, used a pull pot on bright channel to change the cathode resistor value and add a bypass cap on V1B, Feedback resistor changed from 100K to 47k.

[@Riffraff12571]

They are fantastic. I wish I had one years ago. I like this amp more than any Marshall I've ever owned. It's so simple, just plug in and turn it up.

[@roncarter2188]

Just latched onto one of these amps and I can't wait, I've always wanted one and I've got one being shipped to me right now, I really like the mods that you've done to this amplifier. I hear that they are great amplifiers stock and they take pedals really well but what you've done really sounds good man.

[@Riffraff12571]

Thanks. I love mine. It did sound really good stock but the mods made it everything I hoped for. They where easy and they gave it just a bit more plexi DNA than Bassman. It's glorious with a Les Paul straight in. Congrats....you'll love it.

[@Killian_Courtney]

I just bought one and had it modded to Super Lead specs. Changed all caps out and added a master volume. Yours sounds great as does mine now!

[@Riffraff12571]

That sounds similar to what I did to mine, new volume pots, change the mixing resistors, few cap changes in the tone stack, change the slope resistor then my favorite, a pull switch on the bright channel volume pot that drops the cathode resistor on V1B and adds a bypass cap. It brings the snarl. \m/

[@Killian_Courtney]

That's pretty much the same, with the exception of the pull switch. May have to add that one in the future. I jumper mine for that dark heavy sound. Might do the negative feedback mod and add a choke in the future.

[@Riffraff12571]

I jumper mine too. I used the old ground switch for the negative feedback mod. One direction is the stock 100K and the other is 33K. 33K sounds a little looser, more sag. I like the stock setting a little better.

[@Stillkickingarse]

What a tone... wow... Best secret Made in Canada ;-)

[@perfectfan2006]

been running them since 1971

[@JB-bs7vn]

Sounds amazing! What cab and speakers did you use for this demo? Thanks

[@Riffraff12571]

Thanks! It was a V30 loaded Carvin Legend 212.

[@heythere6983]

This sounds pretty good , I literally just Heard about the amps as I was looking into “wang” amps, pronounced Wong, they hand old school wiring and replicate the 1987 and jcm800 amps . They sound nice enough but someone on a forum mentioned these amps. I wonder about the hassle of vintage amps and their transformers and upkeep. I’d have to get a tech to mod it, whatever you did to yours sounds pretty nice though, no pedals huh?

[@Riffraff12571]

'70s Traynors like this YBA1 have oversized High quality Hammond transformers in them. Peter Traynor was originally a tech and designed these for equipment rentals. He built them so they wouldn't blow if someone used the wrong impedance. They can be beaten & abused and keep on rockin'. There's a video on the web of him dropping a head off of the roof of his store and it still worked afterward. As far as the mod goes it's a simple one and I have everything that needs to be done in these pictures: i.imgur.com/36TtVOj.jpg i.imgur.com/z9WwS47.jpg

[@heythere6983]

Nice, it sounds pretty good. I feel like it sounds like a plexi but maybe a little more open and less compressed , maybe the tops a little rounder/sweeter. Do you find combining the bright channel with the bass channel is too boomy? If so, is there a way to mod it to bring in the bass without excessive bottom? Edit, I just remembered you’re using both channels here , bass is strong but sounds controlled . Do you bother to variac to keep the voltage down to where it was back then? I’m assuming 110, or since it’s so durable , it’s not really worth it. Thanks for the response

[@heythere6983]

Also wondering if this was the 40 or 100 watt? I’m wondering if the mods would need to be different for a 100 watt since usually 100 watt amps seem to have more bottom and thickness . I feel like yours here sounds about perfect

[@Riffraff12571]

@@heythere6983 I have the YBA-1 which is the 40W version. There is a YBA-1A which is a 60W version which is very similar and a YBA100 which is a completely different amp.

[@heythere6983]

Thanks. Yeah I was lookin at a yba-1a that is 90 watts. They run very hot and have a fan .Apparently those exist too, every video Iv seen of those don’t sound great but maybe they were not modded . I read those don’t break up the same and I think they have larger transformers so there may be more lows and highs, I’m assuming that would require different values to the mods to get it in a decent midrange tone for guitar . Frankly I don’t know if I’d want more lows and highs . You seem to have yours in a really good spot tonally it’s tasty

[@jobluez]

I need to do some of this on mine, thanks for posting.

[@JeremySteamsack]

Sounds fantastic. Matches early Eddie Van Halen sound in the zero demos perfectly

[@superduperman7202]

I got one under my stairs.

[@MrMudEagle]

Had any problems running this thing with the attenuator?

[@Riffraff12571]

No, none at all and I often set the attenuator to load, jumper channels turn the amp up around 6 - 7 on the bright channel, 4 on the darker channel in typical Plexi fashion and reamp the attenuator's line out so I can add my effects and have better control of the volume without affecting the tone of the amp. It's a rock solid piece of equipment with overspec'd transformers. I'm using a Weber MASS100 with it which has a tone stack for the line out that's excellent for this application.