What transformer should i choose for a 19" rack preamp?

[Rod]

Hello!

What transformer should i choose for a 19" guitar preamp ?

There is also Kit that i could start with?

[The Dude]

We're gonna need much more info than that. Tube preamp or solid state? What is the expected current draw? If tube, how many tubes (filament supply current)? How many rack spaces/How much room do you have? etc., etc. Can you post a schematic?

[Rod]

We're gonna need much more info than that. Tube preamp or solid state? What is the expected current draw? If tube, how many tubes (filament supply current)? How many rack spaces/How much room do you have? etc., etc. Can you post a schematic?

Hello Dude!

Im thinking in building a guitar preamp tube for a 19" rack, im thinking in the smallest preamp to fit a 1 unity of heigth space of a 19" preamp rack.

For Current drawm im thinking something near a modded jcm800, as for number of preamp tubes, maybe around 5 or 6 preamp tubes for a clean channel with is own circuit path and a crunch and lead sharing some preamp tubes.

As soon as i finish the preamp schematic i will post it here.

[The Dude]

Here's an existing JCM800 pre. You'd have to modify for your requirements.

http://www.pisotones.com/GORG/Pabloc..._por_gak_2.pdf

[glebert]

I have a friend who had to replace a PT in an Ampeg SVT IIP, which is a 1U tube preamp and there were very few options, I think he had to use a very pricey one from Mercury Magnetics. He may have had more space constraints than you might have though.

[The Dude]

^^^^^^^^ Agreed. Hard to find something with correct specs that will fit in something less than 1 3/4" tall. It can be done, but I'd consider making it at least 2 rack spaces to give yourself more options.

[J M Fahey]

Just thinking aloud: you might split the job, so split size requirements.

Main constraint is height, no big deal in fitting 2 (or even 3) smaller transformers.
Search for a 6.3VAC transformer with current enough for those filaments and another to feed +V

You might even use a small 2 x 120VAC primary, 2 x 120VAC secondaries "isolation" transformer, wire secondaries in series for 240VAC and use a voltage doubler, you can get almost 600V DC which you can filter and tame down approppriately, or even simple bride rectify it for some 300VDC which might be enough.

[Bloomfield]

Antek has some toroids such as this https://www.antekinc.com/as-05tc300-...v-transformer/ that might work. The nominal height is given as 1.6", so it may or may not fit in a 1U enclosure. Remember proper mounting- don't put a metal bolt through the centre connecting both sides of the chassis.

[glebert]

Will preamp tubes need to be mounted horizontally to fit in a 1U? Maybe use a narrow chassis and mount them out of the back panel.

[catalin gramada]

19" rack size preamp - toroidal transformer FLAT size. Any transformers shop can offer the same transformer in at least three sizes: flat, normal or tall.

[Gregg]

It looks like this one will be able to do 6 preamp tubes in 1U rack:

https://www.tube-town.net/ttstore/to...30va-8808.html

Use voltage doubler for anode voltage.