Hi, I stumbled onto this site the other day when I was reading up on Trainwreck amps, and today I decided to go ahead and sign up today (great little site here, by the way).
My problem is I can't afford a Trainwreck at the moment. So I'm wondering if it's possible to mod my Blues Jr into a Trainwreck-ish sounding amp, or is it impossible. Or would I be better off getting ahold of the parts and just building a clone from scratch.
I looked around a little and did a search, but either missed something on this subject or didn't turn it up. So I apologize if this has been brought up before.
It's a good place to get started learning how to mod what you have, to make it better. The knowledge you gain modding what you already have will help you tackle something more ambitious, like a Trainwreck build. Or you might decide you don't enjoy, or feel safe and confident, doing that kind of work. It ain't for everyone. It's dangerous, even if you do know what you're doing.
In my opinion, it would be an exercise in futility trying to turn a Blues Jr into any of the three types of Trainwreck circuits (Rocket, Liverpool, Express). I don't think it can be done. But as someone that has done all of the BillM mods to the Blues Jr, I can testify that it will improve the tone of that amp for modest cost.
And I can testify that, even after making BillM modes to a Blues Jr, if you have played a TW, any variety, you will realize what a POS the BJ actually is.
Ooh. Harsh. Sorry. In my family, we always told our kids not to "yuck someone's yum."
I build and repair tube amps. http://amps.monkeymatic.com
xtian wrote:And I can testify that, even after making BillM modes to a Blues Jr, if you have played a TW, any variety, you will realize what a POS the BJ actually is.
Ooh. Harsh. Sorry. In my family, we always told our kids not to "yuck someone's yum."
Harsh indeed! I've had a lot of BJ's in my life; I never considered any of them a POS
Thanks, guys. I have been planning on doing some of Bill M's mods to it already, I was just hoping I could add some Trainwreck flavor while I was in there. And I feel comfortable working on amps. Back when I was driving truck, I used to repair my CBs myself and have successfully made a minor mod to my Marshall JVM.
Yeah, I know you're thinking, "This guy has a JVM, but can't afford a Trianwreck?". I had a really good tax return back in '07 when the JVM came out (truck drivers get a lot of deductions), and didn't even bat an eye when I saw it sitting there at the local music store. Man, if I could go back......
So anyway, that answers my question. I guess " build a Trainwreck clone" is now on my to do list.
I had a look at the Blues Junior Schematic. I don't see any real problem with converting it to a Trainwreck, it is basically just moving circuit blocks around and a component value change.
This is the basic idea (YOU need to check).
1)Remove C2
2) shift tone stack to be fed from V1-B pin 8, cut at track from V1A-pin 1 and add a wire to the C2 input pad.
3)Remove R15 and link treble wiper output across to volume control (C2 output pad)
4) Link V1-A (track previously cut) via 2n2 coupling cap to 150K to 0V and 22K into R15 pad which connects to V2-B pin 7 .
5) change R17 to 10K
You MAY then have a low frequency stability problem - if so then, find the B+ feed to R3 and R8 and and cut the track from feed 'Y' and add an extra stage of power supply decoupling (10K + 22uF) .
That (last) is a mistake on the existing circuit which sould have been addressed at design time. You NEVER run more than 2 cascaded inverting stages from the same power supply node. Couldn't read the designers signature nor the checked and approved signatures but there are 3 guys who need a boot in the preverbial.
My 2 cents......your amp will never sound correct, and may likely be worse for wear after modding. Piecing together parts into an amp is the BEST part.....and you will have an intimate knowledge of every component...
Here in Oz I found an old AWV/Philips PA Amplifier from the early 1960's. It was push pull 6CA7 output. I rebuilt that into a Trainwreck. I'm sure that there must be similar old cheap amps in your part of the world which would make a modification or rebuild platform. If you want to see what I did go to the Trainwreck section and search for "Junkbox Trainwreck".
Cheers,
Ian
gingertube wrote:I had a look at the Blues Junior Schematic. I don't see any real problem with converting it to a Trainwreck, it is basically just moving circuit blocks around and a component value change.
This is the basic idea (YOU need to check).
1)Remove C2
2) shift tone stack to be fed from V1-B pin 8, cut at track from V1A-pin 1 and add a wire to the C2 input pad.
3)Remove R15 and link treble wiper output across to volume control (C2 output pad)
4) Link V1-A (track previously cut) via 2n2 coupling cap to 150K to 0V and 22K into R15 pad which connects to V2-B pin 7 .
5) change R17 to 10K
You MAY then have a low frequency stability problem - if so then, find the B+ feed to R3 and R8 and and cut the track from feed 'Y' and add an extra stage of power supply decoupling (10K + 22uF) .
That (last) is a mistake on the existing circuit which sould have been addressed at design time. You NEVER run more than 2 cascaded inverting stages from the same power supply node. Couldn't read the designers signature nor the checked and approved signatures but there are 3 guys who need a boot in the preverbial.
Cheers,
Ian
Wow, thanks for taking the time to look at that. But I've decided to just build a Trainwreck from scratch. It'll take me awhile to get the parts together, but after looking around here some more and reading the posts in this thread, I feel that it would be the better route.
But I've decided to just build a Trainwreck from scratch. It'll take me awhile to get the parts together, but after looking around here some more and reading the posts in this thread, I feel that it would be the better route.
Thanks again.
Great move! Anything worth doing is worth doing right. Take your time, enjoy the process, and have your patience and discipline richly rewarded with a far better amp.
While I'm thinking about it, has anybody used a breadboard for experimenting with a build before soldering everything to a turret board? Or is that too dangerous to even think about? Lol
ETA: And where's a good place to buy a blank chassis?
GoneShootin wrote:While I'm thinking about it, has anybody used a breadboard for experimenting with a build before soldering everything to a turret board? Or is that too dangerous to even think about? Lol
ETA: And where's a good place to buy a blank chassis?
I've seen a web site where someone had done the breadboard thing. Honestly it made me cringe.
For good quality blank chassis, here's one source:
