P2P pultec EQP1A questions

[Deepdark]

Hi folks

Couple of questions for you. I'm building 2 of them, according to cayocosta layout, for a friend.

The original PT was rated 274v-ct. What if i use a 250v-ct PT? Less voltage to the first tube won't be a big issue I guess?!

I was looking at the inputs and output trannys. There is a model from cinemag, for the input one,  rated 600/600 + 18db, looking similar to the sowter one. Is there some particularities i should looking for or it's safe to go with cinemag?

For the interstage, on the schematic, the triad is wired to be 20k/80k, but the sowter replacement is wired to be 2.5k/10k. What's the main influence such a difference make on the sound/general use? I saw a carnhill vtb2424 wired exactly like the triad hs-29. (20k-80k).

For the rotary pots, the greyhill are really expensive. Is it safe to go with lorlin switch? I know some hate them, some like them. Personnaly, i never got Any issues with them. They work really well. Is there some particularities about the greyhill? I guess i should choose non-shorting switch?

For the pilot lamp, if i go with a pt without 12v secondary tap, i could wire the lamp to the heater tap, like on a la2a. I know someone make a voltages multiplier to pluging in a 12v lamp on a 6,3v tap. I would like to know exactly how to do that.

Thanks all. Have a nice day.

 

[ruffrecords]

This tube circuit is relatively insensitive the HT voltage variations so the transformer you have should be fine.

There's nothing wrong with Lorlins as long as you only need the one deck. People use them all the time in my poor man's Pultec desgn.

Cheers

Ian

 

[Deepdark]

Thanks Ian. I'm planning using the lorlin only for the high freq and attn. Selector and the bypass. But why using a 2 deck instead of a regular 2 pole on the bass freq? Do you know something about the sowter interstage tranformer? Is the impedance difference between the triad hs-29 and the sowter 9330 (triad clone) will have an issue on the sound/performance?

 

[ruffrecords]

Thanks Ian. I'm planning using the lorlin only for the high freq and attn. Selector and the bypass. But why using a 2 deck instead of a regular 2 pole on the bass freq? Do you know something about the sowter interstage tranformer? Is the impedance difference between the triad hs-29 and the sowter 9330 (triad clone) will have an issue on the sound/performance?

The popular Lorlins have a single deck. You can get a one pole 12 way or a two pole 6 way on a single deck Lorlin. So if you need two poles then you can only have 6 frequency selections with a Lorlin. There's only 4 lo frequencies on the regular EQP1A so it is not a problem.

I am afraid I know nothing about the various interstage transformers.  It is anybody's guess which part of the circuit contribute to the 'sound'.

Cheers

ian

 

[Deepdark]

Thanks a lot Ian.  ;D