Amp guys, read. '75 Traynor YBA-1.

[ModestCargo]

Hey guys, I have a Traynor YBA-1 Bassmaster that is basically a Fender Bassman 5F6-A circuit with a few changes and an EL34 power section.

Now, the problems with this amp are - it has way too much low end (and it's low low end, not punchy low end) and it's harsh (too much ear piercing high treble). The second "bright" channel is also unusable and will make your fillings ache. The Vintage 30s in my Marshall cab probably don't help as they are bright sounding speakers.

The other problem is the amp has a really nice feel to it - until it gets to my favorite point - where it's clean but breaks up when I dig in. It has a raspy distortion that especially doesn't sound too sweet when playing lead, say, up around the 12th fret.

Here's the plan so far:

1. Change the 500k volume pots to 1meg.

2. Change the 1000pf bright cap to 120pf.

3. Change the tone stack to 5F6 values, and the presence control.

4. Change 100k feedback resistor to 50k to tighten up the output stage.

5. Add a .68 cap with the 820 ohm resistor to give it a Marshall like mid boost. This will be switched on and off via the unused SPST ground polarity switch.

As you probably have figured out, this should take the EQ qualities that I don't like out of the amp and get the preamp closer to 5F6-A territory.

My question is how do I help the raspy distortion? Is it to do with the transformers, and if so, how much difference would Mercury Magnetics or Heyboer plexi style transformers make in the overdrive character? What else can I do? Does the fact that the amp does not have a choke have anything to do with it?

Closest and easiest to read schematic of a YBA-1 like mine:
http://www.informatik.uni-bremen.de/~dace/vb/traynor_bassmaster_yba1a.pdf

Bassman schematic:
http://www.drtube.com/schematics/fender/bassman-5f6-a-schematic.gif

Here's the Marshall 1987 circuit.
http://www.drtube.com/schematics/marshall/1987u.gif

 

[Rich_S]

Re: Amp guys, read. '75 Traynor YBA-1.

I wouldn't mess with the transformers. IIRC, Traynor used pretty good ones, so the benefits of swapping them out are going to be small compared to the cost.

I think with some patience, the low-dollar mods you have planned (EQ and feedback, especially) can get you what you're looking for.

Not having a choke might make the amp a bit saggier - don't worry about it for now.

 

[J Moose]

Re: Amp guys, read. '75 Traynor YBA-1.

When was the last time the main filter caps were changed?

If the answer is probably never... or more then 15-years ago... start by changing those before any other mods are completed.

Those are pretty solid amps, shouldn't be overly low-endy or harsh... probably caps. If not the cab/speakers...

 

[drew_half_empty]

Re: Amp guys, read. '75 Traynor YBA-1.

ok man

first, it has 1 meg volume pots now, take em down to 500k

then put in the bright cap like you said

then put in a 33k slope resistor

then bias it a little hot, just a little, and put it back together

you'll be happy. i promise.

oh and for tubes i found SED's work best for the EL's and jj's for the preamp

 

[ModestCargo]

Re: Amp guys, read. '75 Traynor YBA-1.

It has 500k pots, I want to use the Fender/Marshall stock value of 1meg. The earlier Traynors had 4 meg pots and that's what I expected but they turned out to be 500k.

Can you please point out the "slope resistor" on the schematic?

Filter caps were changed about 6 months ago.

 

[jeremy]

Re: Amp guys, read. '75 Traynor YBA-1.

that .68 is only gonna make it brighter. those amps are pretty nice and with a little work you should be able to get it to sound really nice

 

[kevlar3000]

Re: Amp guys, read. '75 Traynor YBA-1.

I have several earlier ( late 60s early 70s) Traynors which were easy to dial in via a simple change or two. I then had a later bassmaster combo that I just could not get to warm up. A very different feeling and sounding amp. I ended up trading it for a 68 Bassman.

Do your mods, one at a time so you can hear what each one does, if you get it sounding great save that recipie! It would be helpful for others that have later models.

 

[Lewguitar]

Re: Amp guys, read. '75 Traynor YBA-1.

Now, the problems with this amp are - it has way too much low end (and it's low low end, not punchy low end) and it's harsh (too much ear piercing high treble). The second "bright" channel is also unusable and will make your fillings ache.

You're describing the tone of a tweed Bassman. :lmao: I've always said they have to much bass and to much treble.

One thing to try is, if there's a 250 mfd. cap on the cathode of the first 12ax7 (It's a 12ay7 in a Bassman) try something smaller like 25 mfd cap. That'll cut back some on the excess bass.

I'll see if I can get Bruce to post on this thread with some advice.

Also, buy Dan Torres book Inside Tube Amps. Or call him for his kit on modding that particular Traynor. He has a chapter on modding the Traynor like yours in his book.

That's a great book for a beginner.

Don't send him your amp though. The work out of the Torres shop is legendary for being sloppy.

Lew

 

[Lewguitar]

Re: Amp guys, read. '75 Traynor YBA-1.

http://search.store.yahoo.com/cgi-b...http://www.torresengineering.com/nsearch.html

 

[Rich_S]

Re: Amp guys, read. '75 Traynor YBA-1.

Dave Hunter's article in the new Vintage Guitar magazine that arrived today is on the YBA-1.

 

[ModestCargo]

Re: Amp guys, read. '75 Traynor YBA-1.

Sounds like I should have played through a Bassman to see if I liked the sound, before trying to buy something and mod it to be a Bassman. Thanks Lew.

I'm seriously thinking about selling the ****ing thing. I jammed with a keyboard player today and I could have taken a ****, plugged my guitar into it, and got a better sound. Sounded like a pile of ****. Couldn't get anything dialed in. In no time I was getting the Deluxe Reverb out - ahh, there it is.

Edit: Never the less, I'll have a look at that VG article.

 

[Rich_S]

Re: Amp guys, read. '75 Traynor YBA-1.

Unlike most Dave Hunter articles in VG, he isn't just recounting the history of some classic. His take is, yeah, the sound is meh, so here's what a lot of people do to fix it. It's a well-built amp with bad voicing.

Here's what I recommend you do:

1) Box it up securely with the tubes pulled and wrapped separately.
2) Take it to the Air Products plant in Forest Park.
3) Ask for "Russ" or "Koz".
4) Give it to them, tell them to check it as baggage on their next trip home.
5) Tell them, once they are back at corporate headquarters, to put it in intercompany mail with my name on it.
6) You'll never have to listen to it again. :joke:

 

[Lewguitar]

Re: Amp guys, read. '75 Traynor YBA-1.

Sounds like I should have played through a Bassman to see if I liked the sound, before trying to buy something and mod it to be a Bassman. Thanks Lew.

I'm seriously thinking about selling the ****ing thing. I jammed with a keyboard player today and I could have taken a ****, plugged my guitar into it, and got a better sound. Sounded like a pile of ****. Couldn't get anything dialed in. In no time I was getting the Deluxe Reverb out - ahh, there it is.

Edit: Never the less, I'll have a look at that VG article.

You know...you shouldn't give up on it. If you don't have much $$$ into it you can have it modded into a very respectable sounding Marshall 50 watt Plexi kind of sound.

The quality of those amps is very high. They're ugly, but still, those excellent Hammond transformers and hand wired circuit board make it very much worth fixing up.

Lew

 

[Lewguitar]

Re: Amp guys, read. '75 Traynor YBA-1.

Which one of these does your amp look like?

BTW, here's alittle more info on your amp: http://www.traynoramps.com/products.asp?type=11&cat=66&id=394#yba1