Liverpool PT Choice

[ckpop]

I needed some input on my choice for my Liverpool PT. I have a Pacific K&M spec PT 250-250/280-280. Now Allyn uses ken's line card spec of 260-260/300-300 which is correct for the express.
My question is Allyn's spec correct for a Liverpool amp ? The difference would between 395v with the K&M spec and 410v-420v with Allyn's correct express.

I was wondering just because 395v would seem to be a comfortable B+ on EL84's instead of 420v. Maybe I'm thinking too much but what do you guy's think about this ?

Trying to see what B+ most are going with on the Liverpool ?

[dave g]

Personally I don't like going above 350 volts for EL84s. I even prefer to keep them under 300. The lower voltage taps are there for a reason...the Liverpool is meant to use the 250 or 260 volt tap

[RJ Guitars]

The transformer thread where all that talk about 280-250-0-250-280 versus 300-260-0-260-300 was reasonably well sorted out in some of the later posts by rhinson. In that thread the Pacific Trannies you have mentioned were identified as appropriate for the Express and Liverpool amps. It all has to do with whether the transformer voltage rating is provided using a loaded or unloaded value.

In other posts rhinson has explained his role in providing the specifications for Heyboer for the 300-260-0-260-300 Power Trannies. rhinson is "The" transformer guy and has led us through the history of these things several times. I've studied his old posts and he is consistent and well informed on all issues of Trainwreck transformer technology. If he says the Pacifics are the right stuff, they are the right stuff.

If you have an inclination to color outside the lines, it is entirely reasonable for you to actually change the dropping string resistor values to tweak that voltages to the exact value you want. This is not "True Clone" procedure but kind of a no-brainer operation if getting an exact voltage value matters to you.

It might also be interesting to consider that the voltage you plug into is probably higher than was common in the heyday of Trainwreck amps. Even today the voltage varies greatly across the US and into Canada. These differences may as significant as the ones you're concerned with between the different transformers.

Just for grins, Google K&M Analog Designs. These were some of the very first guys to clone the Trainwreck amps. Interesting read and also gives you some confidence that the Pacific trannies are the right stuff.

rj

[M Fowler]

When I built my Liverpool there was no one saying not to use the suggest Heyboer HTS-5199 noted as supplier number 11410 TWPT. It was the accepted PT of choice.

The problem lies with the Express and when I wanted to build my first Exact Clone I went with Allynmey's recommendation of his line card Pacific trannies rather than the Heyboer.

The Rocket recommends Heyboer PT and Dynaclone A-470-S. But there again I used Edcor PT and the A-470-S OT.

Even Ken Fischer used what he had on hand and changed suppliers during his TW era.

Mark

[M Fowler]

To waste more time I am going to start a chart. Work in progress.