One-Bottle Preamp

[ForthMonkey]

He says "i've quiet kill the ringing with a 470pf cap+18K resistor".Is this ok for this preamp?

BTW this transformer has no its own screening.Should i buy screening can?

 

[gemini86]

The zobel network is tailored to the transformer, mostly. So, it should work fine in this amp. A screening can is nice, if there's a lot of interference in your chassis, but you can make a quiet amp without by using physical distance from any AC power sources.

 

[ForthMonkey]

The zobel network is tailored to the transformer, mostly. So, it should work fine in this amp. A screening can is nice, if there's a lot of interference in your chassis, but you can make a quiet amp without by using physical distance from any AC power sources.

Thanks to answer.For now i have no problem about components.12AV7 on the way but...

I can't find power transformer for this amp.Actually i have a transformer for tube amps.

Pri=220V
Sec=2x190V
Heather=6.3V
Power=60W

I think it's not enough for this amp,right?

 

[gemini86]

It would be really useful to know what the heater supply current is.

But if it's 60W total, that should be more than enough. Even a 30W transformer should be enough to run this preamp.

 

[ForthMonkey]

It would be really useful to know what the heater supply current is.

But if it's 60W total, that should be more than enough. Even a 30W transformer should be enough to run this preamp.

I got this transformer for free and it's just standing.Actually i don't know what is heater supply current but i asked my friend.He knows.I'm waiting for answer.

 

[bruce0]

Is there a schematic anywhere for this?

 

[gemini86]

Schem

 

[gemini86]

Specs

 

[Kingston]

A closely related "no-feedback" mod that also seems to have disappeared.

 

[Kingston]

The "two bottle" version for increased gain. (was also posted in this thread and lost)

 

[ForthMonkey]

It would be really useful to know what the heater supply current is.

But if it's 60W total, that should be more than enough. Even a 30W transformer should be enough to run this preamp.

My friend doesn't know,too.But i think it's okay for this preamp,right?

 

[rock soderstrom]

A closely related "no-feedback" mod that also seems to have disappeared.

This is my favorite OneBottlePreamp. I have build it up with a 6cg7 and a slightly hotter first stage. Wow, that's a tube amp! (...for a rock'n roll guy;-)

 

[L´Andratté]

Thanks, Gemini and Kingston, for updating!
I think, some not too distant day this will be my first tube project!

 

[gemini86]

It would be really useful to know what the heater supply current is.

But if it's 60W total, that should be more than enough. Even a 30W transformer should be enough to run this preamp.

My friend doesn't know,too.But i think it's okay for this preamp,right?

I'd just go for it... at 60W, there should be an abundant supply of heater current. I would bet there's around 2-3 amps available there.

 

[ForthMonkey]

It would be really useful to know what the heater supply current is.

But if it's 60W total, that should be more than enough. Even a 30W transformer should be enough to run this preamp.

My friend doesn't know,too.But i think it's okay for this preamp,right?

I'd just go for it... at 60W, there should be an abundant supply of heater current. I would bet there's around 2-3 amps available there.

Yes,i think like you.I'm still waiting my shipment.When i build all circuit,i will try my xformer.If it doesn't work,i will try anything else.

Thanks for helps.I have some questions but i will ask while i build.

 

[ForthMonkey]

Can i use 400V caps instead of 450V?

 

[Kingston]

Can i use 400V caps instead of 450V?

With your particular PSU transformer, yes. See the LA2A schematic on how to configure your high voltage supply. It's perfectly compatible.

 

[ppa]

how does one bottle preamp sound?

 

[Kingston]

how does one bottle preamp sound?

It sounds like the transformers you choose. The very simple design and relatively high amounts of feedback are very transparent. No "tube warmth" to be found, just a very flat traditional high gain utility amp. Pretty much the same with two bottle version. Something like 0.1-0.3% THD+N on common gain staging scenarios. (NYD's spec above was with no output transformer and very loud output)

The non-feedback version on the other hand can sound a bit "farty". It doesn't clip particularly nicely or "warm", but more a guitar overdrive type effect.

 

[ppa]

Nice, since the circuit is small which uses one tube only so the heater current is reduced so it is possible to place side by side 4-6 channels in a single 2U chassis, with the PSU inside. 
What do you think a version with an output stage with a solid state buffer with the advantage to have a trasformerless out too? It could reduce price and space.