Building a Trainwreck Express - Please talk me out of it

shaunf

I dunno why, but ever since I heard and saw them on Youtube, I've been obsessed with owning one of these amps. For some reason, all I have been able to think about for nearly a week now is building one.

Please talk me out of this! The obsession is ruining my life!

singemonkey

I suspect EZ's gonna talk you into it. He gets a weird twitch every time they're mentioned.

ezietsman

:-[

Do a 6V6 model and put in VVR also and you're 8)

shaunf

Why 6v6 and not EL34?

VVR is a definite!

ezietsman

Well, EL34 is probably OK but you'll need to very carefully think about the cooling of the mosfet if the power output nears about 50W. I always thought these amps were closer to 100W but Makepeace told me they're closer to 35 W and likely closer to 20 Watt with the 6V6s. IF they're about 35 Watt with EL34s then thats prob OK. Those mosfet chips needs to be cooled somehow, if they are eating up less than 20 watt bolting them to the chassis is fine (with the heatsink paste and the insulating washer) but if they need to eat more you will need to be careful about it, else it'll burn out. I think up to 50 watt is OK with this method.

VVR with fixed bias is more tricky and doesn't work as well (from what I've seen) if you have to scale the amp back to less than halfway. The 6V6 version will not be so loud so you'll go easier on the VVR too ?

rikus

ez wrote: :-[

Do a 6V6 model and put in VVR also and you're 8)

Holy crap! InstaGAS! Would a tried and tested schematic for something like that we available online?

ezietsman

I haven't looked much. Ceriatone has a schematic but I'm sure one of the various fora dealing with DIY amps will be able to provide all the necessary info.

shaunf

ez wrote: Well, EL34 is probably OK but you'll need to very carefully think about the cooling of the mosfet if the power output nears about 50W. I always thought these amps were closer to 100W but Makepeace told me they're closer to 35 W and likely closer to 20 Watt with the 6V6s. IF they're about 35 Watt with EL34s then thats prob OK. Those mosfet chips needs to be cooled somehow, if they are eating up less than 20 watt bolting them to the chassis is fine (with the heatsink paste and the insulating washer) but if they need to eat more you will need to be careful about it, else it'll burn out. I think up to 50 watt is OK with this method.

VVR with fixed bias is more tricky and doesn't work as well (from what I've seen) if you have to scale the amp back to less than halfway. The 6V6 version will not be so loud so you'll go easier on the VVR too ?

Cool, thanks, will bear that in mind.

shaunf

rikus wrote:
ez wrote: :-[

Do a 6V6 model and put in VVR also and you're 8)
Holy crap! InstaGAS! Would a tried and tested schematic for something like that we available online?

Pretty much everything you need to know is located here:
http://ampgarage.com/forum/viewforum.php?f=3&sid=1d6dd061fbd47a0f474122872e9b1d11
(You need to register as a member of the Ampgarage forum before you can view and download these documents. Well worth it though. Someone put a hell of a lot of work into all the info there.)

MikeM

El34 is where it's at.

I say build it. You might even be able to get away with a MV and not a vvr even ?

aja

Just buy one.

http://www.ultrasoundampsales.com/amp_browser.php?ampid=56

makepeace

I say what the shit are you waiting for ?

Think I've said this, but the EL34 version is pretty much a tweaked Bluesbreaker. So yeah, the roof is probably 35W, but you would probably press mid (maybe high) 40s. You can do this with a VVR. Have a look here: http://www.hallamplification.com/main.html?src=%2F#2,2. You'll just need to do some good planning. But if it were me I'd build most of it and then compare the Lar/Mar post PI master volume with a VVR, and if they're both useful, put them both in.

Also, here:

http://www.blueguitar.org/new/schem/trainwreck/wreckxpr.pdf

?

PS. I'd seriously give the 2 x EL84 versions some thought.

Wizard

I think I need a quick crash course here on the difference between the sounds of 6v6 and EL84 etc ...

makepeace

Pretty much (and this is a terrible generalization, as there's an innumerable number of other factors involved)

EL84 = Vox (AC15, 30)
6V6 = Fender (think champs, deluxes, DRs, princetons etc)
6L6 = Fender (bandmasters, bassmans, etc)
EL34 = Marshall (JTM45, 50, 100 etc)

Pretty much hard to describe otherwise.. I was mainly referring to the fact that you'll get quite a bit less power out of the EL84s than the 6V6s and way less than the EL34s, which may be useful.

nicovlogg

makepeace wrote: EL84 = Vox (AC15, 30)
6V6 = Fender (think champs, deluxes, DRs, princetons etc)
6L6 = Fender (bandmasters, bassmans, etc)
EL34 = Marshall (JTM45, 50, 100 etc)

That's also in descending order of tonal desirability. [ducks] :?

MikeM

nicovlogg wrote:
makepeace wrote: EL84 = Vox (AC15, 30)
6V6 = Fender (think champs, deluxes, DRs, princetons etc)
6L6 = Fender (bandmasters, bassmans, etc)
EL34 = Marshall (JTM45, 50, 100 etc)
That's also in descending order of tonal desirability. [ducks] :?

ezietsman

=

Even the strat sounds good through an Express }?

makepeace

nicovlogg wrote:
makepeace wrote: EL84 = Vox (AC15, 30)
6V6 = Fender (think champs, deluxes, DRs, princetons etc)
6L6 = Fender (bandmasters, bassmans, etc)
EL34 = Marshall (JTM45, 50, 100 etc)
That's also in descending order of tonal desirability. [ducks] :?

Haha.. Totally unintended, guess the subconscious had its way.

Just another NB, your choice of OT will be very important. I wouldn't know where to start with that one.. Also, you're going to have to put metal resistors in wherever possible and plan your layout carefully.. Apparently the noise tendency of these amps is overboard.

MikeM

makepeace wrote:Just another NB, your choice of OT will be very important. I wouldn't know where to start with that one.. Also, you're going to have to put metal resistors in wherever possible and plan your layout carefully.. Apparently the noise tendency of these amps is overboard.

Keep them a high wattage too. If you're planning to order some "high end"-ish types, I've done some research and found really decent resistors for a reasonable price.

Attila

Hell no Shaun ..... Just Do it !!!! Dude

Finished my Carolina Songbird D-style amp the other day and loving it