Pre-Express build questions...

[Tonegeek]

After spending years in TAG's Dumble area, I am now drawn to building something similar to a TW Express. I say "similar" because I have no desire to make a physical clone. I do however want to get the amazing tone of the Express and will stick with what works in terms of small parts, layout and schematic to achieve that goal. I am not too keen on the Bud chassis and if a thicker aluminum chassis will work, I would prefer that. I would keep close to the original dimensions otherwise. I would like to get the transformers that work best for this amp but if I have a choice, would prefer ones that give up the goods at the lowest volume. I have read on this forum that some Expresses are louder than others and it seems some of that may be due to the transformers. Of course other components (tubes for sure) can affect the output as well, but those things I can afford to experiment with. I plan on using EL-34 tubes, not 6V6.

In that regard:

1) How much does the Bud chassis contribute to the sound? I would rather use a 2mm (.090") thick aluminum chassis. Has this been done without sacrificing sonic quality?
2) What would be the best transformers (especially the OT) to use? Given a choice, I want the amp to have the best tone, touch, harmonics and feedback at the lowest volume (doesn't everyone!) I understand some of the available PTs have 260 and 300 VAC windings. It appears most people use the 300V winding for the Express. Is that correct? I see that Edcor has a 6.6K 30 watt OT. Has anyone tried it? Here is the link: https://www.edcorusa.com/cxpp30-ms-6_6k Also Mojo has something similar and it appears to be the Heyboer HTS 5200. And, Magnetic Components has an OT that would work. I have had great results with some of their other trannys. Anyone used MC in their Express builds?

If I wanted to use Pacific trannys (2112, 2113), where can I get those? Are they a special request?

Finally: What gauge wire is used? It seems I read #20 except for the heaters. Solid or stranded?

I look forward to building this amp!

thanks,
Whit

[martin manning]

TAG member rj can fix you up with a nice sturdy chassis and a transformer set from a couple of options.

[RJ Guitars]

Thanks Martin!

As far as transformers, i like the Edcor transformers as much as anybody, and i sell a ton of them. They are #1 on my list for a power transformer in a Wreck. However, the high gain Wreck amps and the 30ish watt Edcor output tranny are not an especially good match in my experience. I did some pretty extensive testing on this and it turns out that if you can't score an old Stancor A3801, then a clone of that same unit works quite well.

As far as A3801 clones go, i ran a thread on that testing and there are a few good options. For the original Express sound and maybe a bit of darkness go with a Pacific. For clarity and fullness i liked the Mercury Mag A3801 clone they wind for me best... lots of options but Edcor was down the list a bit.

FWIW - the 15 watt OT's that Edcor winds for me, they sound awesome in a high gain amp... its a mystery to me??

[Tonegeek]

RJ, I read with great interest about the experiments you spearheaded using printed circuit boards for the Express amps. I have a similar mindset when it comes to building amps. What really gives me satisfaction is to achieve the sound of whatever amp it is that I am trying to emulate, but do it in my own way. And the icing on the cake is when I can enhance the original design to my personal taste. I also am interested in building amps at a reasonable cost, especially now that my financial status is not what it once was (being your own boss is costly!). Also as a matter of full disclosure, when I build amps for other people, it helps me as well to keep the parts cost in check as long as the tonal goals are met. In that regard I am hoping to get more responses to my original post concerning transformers that have been tried in these amps. If it turns out there is not enough data on the Heyboer HTS5200, Edcor CXPP30-MS-6.6K, or the MC 40-18064 then I may try them myself and report my findings here. If, on the other hand, the TAG community has ruled out these and other components, then I will not beat the dead horses.

BTW I agree that I can't go wrong with the Pacifics. I have unlimited access to one of Allyn's Pacific equipped Express clones and hearing this amp is what got me interested in building one in the first place.

So to recap:

1) I am interested in more opinions on transformers tried in the Express.
2) Might as well get this out the way too: Brands of current production caps that work well in the Express.

Thanks,
Whit

[RJ Guitars]

Whit,
For a long time the Heyboer clones of the Stancor A-3801 were the gold standard for Express clones. The HTS9633 aka 5200 is a great transformer and is a variant of that lineage. For a few years the standard in the Express was the HTS9384, the 6.6K variant of that same line. These two trannies were known as the vintage series and were great sounding iron... tens if not hundreds od Wreck clones used these OT's. These were preceded by a model that had both the 5.2 and 6.6K taps (I don't recall the #) and it was recognized as a bit edgey and aggressive sounding in comparison tot he Vintage series.

I sold a ton of the Heyboer trannies until Pacific sorta emerged as the more correct and ultimate answer for Express iron. I still keep a few Heyboers around to listen to and compare with. I actually like them better than the Pacific because they have a little more life to them... 2nd only to Mercury Mag on my favorites list for an Express.

[Bonsaimaster]

As for chassis they are not going to affect the sound per say. An open chassis does give advantages of separating components. More cooling less crowding are important but there are diminishing returns. Therefore there is an adage of open spacing open sound. As for transformers I have used Classic Tone's in my Trainwreck builds. They are spec for the Express and Liverpool circuits. They sound great and are reasonably priced. I would recommend them over the Edcor. The trainwreck circuit is simple and well designed. Use good gauge wire 18 for power and 20 for interconnections. I use MIL spec Teflon but that is overkill. Don't use cloth covered wire or solid core for builds. Resistors can be 1/2 watt and does effect sounds with different brands. Tolerance is more important for consistency. Capacitors can make some difference in sound but I like both Orange Drops and Mallory. Anything more exotic is a waste of money. There are some good modifications of the circuit to make it less harsh sounding. Tube choice is also the most important to effect sound. Along with speakers and pickup choice.

[geetarpicker]

i'll first mention I own an original '89 Express (bought it new) and an '85 Express so I have quite a bit of experience with them.

I will say the best sounding and feeling TW clones I've played were built on original thin Bud chassis with the screwed on bottom plates. It is quite accepted that aluminum chassis can sound different than steel, and I believe the concept is debatable that there may be a slight audible difference between a thin and much thicker aluminum chassis especially if we are talking almost 3 to 4 times the metal. I've heard that JM is building the new "authorized" Trainwrecks on thin Bud chassis. Apparently he thought it was worth the sizeable order he must have placed with the manufacture to have them build this otherwise discontinued part. That said it might be more marketing to stay with Ken's recipe. Still it would take some effort to build two otherwise identical amps to compare chassis thickness on tone. IMHO I think there are still some aspects of these amps that have yet to be fully figured out.

I'd perhaps suggest the Pacific transformer set if you have seen and liked my videos with my '89 as it has Pacifics. On the other hand with original Stancor a3801 transformers showing up on eBay there is also the option to use the same OT used in the earlier tamer and more bluesy sounding TWs. NOS may be pricey, but used ones come up for much less money. I guess I'm biased a bit here, as my '89 has Pacifics (6.6k OT) and my '85 has the grey bell Stancor OT.

My originals have solid core PVC signal wire, stranded filament wiring, and just a couple wires off the power supply (screen feed to power tubes) use a larger gauge stranded wire.

I'd also suggest the original spec PVC signal caps and the Mallory TC electrolytics if you can find them.

Hope that helps! GK