Trainwreck With Power Scaling ???

[boogieongtr]

I have been hanging around this forum for a while but just joined a couple days ago. I have been using a Komet Concorde as my main amp but after hearing Glens Trainwreck clips I thought I'd give one a try. I am having a Trainwreck clone built with the London Power scaling kit installed. I am curious, has anyone done this build before with the power scaling? Any feedback would be appreciated, thanks.
Jim

[UR12]

I have been hanging around this forum for a while but just joined a couple days ago. I have been using a Komet Concorde as my main amp but after hearing Glens Trainwreck clips I thought I'd give one a try. I am having a Trainwreck clone built with the London Power scaling kit installed. I am curious, has anyone done this build before with the power scaling? Any feedback would be appreciated, thanks.
Jim

Hi Jim

There has been a few guys build TWs with power scaling . Which amp are you having built? (Express/Rocket/Liverpool)

[boogieongtr]

Dana,
Thanks for the reply. I'm having the Trainwreck Express built. I'll do a search to see if I can find an Express with the power scaling.
Jim

[UR12]

I think most of the guys here have scaled Liverpools. The Express has fixed bias and requires KOCs bias tracking circuitry to get it to work. I'm pretty sure if you do a search someone has also done an Express. It should work really good depending on how low you want to go. Are you having the whole amp scaled or just the power amp section?

[boogieongtr]

I am meeting with the builder next Saturday. I'm not sure at this point as I don't need bedroom level DB but want to use the amp for small club work as well as outdoor festivals. The builder is Nate Burks - owner of Bumbox Amps and is licensed by London so I hope to get a good schooling on the PS.
Jim

[UR12]

Keep us posted on how everything turns out.

[Matt72]

If you're not worried about in-home volume levels, and just want small club and outdoor, a good alternative is a pentode/triode switch. That'll give you about 34w or 17w or so and you can keep it "stock" in the pentode position. Give you 18 ro 9watts too with 6v6s.

[racerx23]

Hey guys

Hey UR12 any chance you can show us how to wire in a ...
''whole amp scaling system'' using just one pot in place of a ppimv.

Craig

[Fischerman]

I built a power scaled Express. However, my Express never sounded right (not uncommon IMO*) and I can't say for sure if the scaling had anything to do with that (all voltages were spot on...I can tell you that). But the power scaling worked very well. I think you can get somewhat close by using a good post-PI MV but the scaling makes it even better. Most people either scale just the power tubes or the power tubes + PI but somebody here scaled their whole amp and reported good results. IMO/IME...for an Express it's best to scale just the power tubes but that might depend on how well your post-PI MV works.

* - IMO many homebrew Expresses don't sound right...my amp did the ZZ Top thing but it's not difficult to get a homebrew Express to do that (they'll all do it). It would get the feedback too but it still wasn't right. It didn't sing/sustain right, didn't clean up right, and was too harsh/bright/aggressive. I'm trying to be picky/discriminating here...I'm not going to be satisfied with an amp that doesn't sound any better than a good pedal. It sounded good but I'm not satisfied with just 'good'. I'm in the process of making a whole new preamp board...based on the Concorde.

[Paul86]

Hi everyone, sorry to jump the thread but I'd like to ask Fischerman to keep us posted. I followed his thread on a PS Wreck with interest. I'm about to do the same with my amp - an Alessandro Bloodhound, but I'm having cold feet because I don't want to change the sound of the amp. Unfortunately, there's no more place for so much volume in my life anymore, and attenuators kind of spoil the fun for me. Keep us posted, please.

[Fischerman]

Paul, the power scaling in my amp worked fine...my 'problem' with my amp is the same ole problem that people have always had with building Expresses. I have been a member of Ampage for years and messed around with the Express circuit in the late 90's when I first found the .pdf file on Blue Guitar with all the different versions of the Express...people were having the same problems with them at that time as well. I liked the K60 preamp a little better than the Express and I liked the Concorde a little better than the K60...so Concorde it is.

[Paul86]

And what about the heat issue? I worry a bit since the head is such a small one.

[UR12]

Hey guys

Hey UR12 any chance you can show us how to wire in a ...
''whole amp scaling system'' using just one pot in place of a ppimv.

Craig

That would depend on the amp your installing it in. The circuit i'm using only works on Cathode biased amps. Basically you break the connection from the input to the first filter caps and insert the powerscaling circuit there so that every voltage in the amp is scaled instead of just the power/pi.

And what about the heat issue? I worry a bit since the head is such a small one.

There really isn't a heat issue up to about 35 watts. Once you get to say 50 watts you need to look into a way to dissipate the heat.

[Paul86]

The amp is 55 watts. Would I have to use heatsinks/ventilation?

[UR12]

The amp is 55 watts. Would I have to use heatsinks/ventilation?

Short answer is yes. I would be looking for some kind of heat sink and ventilation for the cab.