Might be heresy - but will this PT be ok on a TW build?

[Axeplyr]

The Convertible Universal Multi-Tap Transformer...

http://www.triodeelectronics.com/the-co ... ormer.html


Has anybody seen this guy??? Looks pretty cool to me!

Would it work (and sound ok)?

[jaysg]

That would probably work fine, however, it doesn't have the current capacity that the HTS-5199 has (300mA vs. 210mA)...and it's more expensive.

[GrungeMan]

For $134US? you could almost buy a TW set for that kinda dough from Moose or someone else.

That looks like a Fender tranny.

As stated by another poster it doesn't have the prescribed current for a TW which is around 300ma.

Power tranny's don't sound, Output tranny's do.

Grungy

[mcrracer]

Talk to RJ or Allen-Mey

[Cliff Schecht]

For $134US? you could almost buy a TW set for that kinda dough from Moose or someone else.

That looks like a Fender tranny.

As stated by another poster it doesn't have the prescribed current for a TW which is around 300ma.

Power tranny's don't sound, Output tranny's do.

Grungy

I'll disagree with that. Power transformers will have an effect on the sound in that switching from an underrated supply to an overrated one will cause an audible increase in transient response. The PT works with the reservoir caps to build up that reserve and if you put a big continuous strain on them, you're going to sag and get more compression.

[geetarpicker]

I agree that the power transformer is a key to the puzzle. A Trainwreck relys on the power supply sag for part of the natural compression, and if you measure the B+ you will notice the sag is quite apparent. This in turn leads to some net volume sag when you push the amp and yet more dynamics when backed off as the PT recovers for the clean work. This is part of why the wreck does so well with the clean to mean range, with little volume change. I think part of this natural PS sag is from the resistance string on the B+, the PS caps, but also in the power transformer it self. In some ways Ken simulated the sag one associates with tube rectifier circuits, but he carefullly tweaked it so that it doesn't sound too mushy. Most tube amps have a power supply that sags a bit on demand. The trick to the wreck however is I think Ken worked with this aspect closely and came up with a nice spec for the PT that worked well along with the somewhat smallish OT and low B+.

This isn't to say a wreck can't be built with a varity of PTs. Just that the expected results might be quite different, especially in the feel, bloom, and dynamics. Point is the PT may make quite a bit more difference in a wreck than most amps.

[lumox0013]

I understand the theory butt isnt 300ma higher than most amps ,how does this create sag or are you speaking of the 600vct? thanxx

[rooster]

That's an interesting thought, Glen. And now, in looking at the Tonesluts spec sheet for the PT, I see that the filament rating is listed (7.5A) but not the B+. For that matter, does anyone know exactly what the Pacific rating is?

I hadn't really thought about the Express from this perspective. This said, I think the real compression starts with the 1K choke, and of course the power caps - but I'm willing to see what others have to say about this.

And to be clear Glen, you are suggesting that a PT with, say 500ma of B+, would probably ruin the stock Express feel, provided the stock PT was 300ma or so. Right? Glen, do you or does anybody know what a stock Express PT delivers for B+ current? I have not seen that number kicked aroung here as far as I can recall.

[geetarpicker]

If you measure the B+ right at the center tap you will see a noticable amount of sag when you push the amp into strong overdrive. Short of a regulated power supply I don't think there is much of a way around it short of a pretty substantial overbuild. Point is most power transformers will deliver more voltage when stressed lightly, such as in an Express when played clean and/or with the guitar backed off. However if one built an Express and used a master volume backed way down or VVR I wouldn't think it would make nearly as much difference what PT you used. However if the amp will be played cranked in the sweet zone I'd personally go with an original spec PT. Also since in the Express the bias taps off the same PT feeds as the B+ perhaps there is even some interaction happening there that also contributes to the clean to mean potential. On the other side of the coin perhaps a PT with a weaker current delivery than "stock" would be too compressed and mushy in an Express. Just speculating, I could be out to lunch on all this...

[paulster]

The Express PT is very stiff for its application, but will still have some sag under load.

The major sag in the amp will be coming from the dropping string, and also the 1K 'choke' resistor, which will cause the screens voltage to bog down under load.

Changing out the PT for a smaller one will likely yield more power supply compression as the transformer struggles to maintain the supply voltage at high current, which could end up too squishy and mushy, rather than being right in the compression zone that Ken has engineered for.

The power supply is a system, particularly as regards the compression, and in this amp it's a key part of the Trainwreck experience.

[GrungeMan]

Cliff wrote:

I'll disagree with that. Power transformers will have an effect on the sound in that switching from an underrated supply to an overrated one will cause an audible increase in transient response. The PT works with the reservoir caps to build up that reserve and if you put a big continuous strain on them, you're going to sag and get more compression.[/quote]

I reread the question.

I agree the 300ma current makes for a better regulated more efficient power PT and that sag is created from a less efficient PT such as the one in question and that sag is not part of the TW's mystique.

I'll clarify that I don't see compression and sag as tone but yes, sag does affect the sound.

[Axeplyr]

Thanks for the replies.

I should probably clarify that I'm interested in this PT not only as a Trainwreck PT. I really want a platform for experimentation, and noticed that the website specifically mentioned Trainwreck as an option. So I figured I'd ask the gurus if it was really suitable, or more of a marketing ploy.

I like the fact that it is a chameleon, and I can use it to try various combinations of B+ voltages and ss/tube rectification. While I am waffling between a Plexi circuit or a Trainwreck circuit, I like to have the option of possibly trying both with one PT. That said, I really just want two EL-34's in the power stage. The rest will be trial and error.

But judging from the response here, it might not be such a good idea?