Triodes plate voltage

[hentai]

Hi, i'm thinking to build a preamp for my bass guitar using some triodes and pentodes. My question is does the plate voltage needs to be that high like in most schematics 150-350 V? If i drop the voltage the plate current will drop 2 but i dont need much current output for it will drive a solid state buffer. My main concern is if I use lower plate voltages will this have an effect on the input range, the grid voltage? Will it affect the dynamics? or this can be solved by biasing the grid the right way?
thx

 

[Nigel Goodwin]

Personally I don't see the reason for using a valve preamp at all, and certainly not for bass - but if you want to produce the high distortion, poor frequency response, of a valve? - then use the proper high voltages and circuits. The anode of the triodes don't run that high, the anode load is a high resistance so drops it considerably - this is an important function of the circuit, and probably partly responsible for the poor sound you're looking for!.

 

[hentai]

Yes that distorted sound is what im after. I dont know why are u refering as poor sound i have an intrument amp (it has a bass guitar input) with 2EL84 finals and sounds really nice. Still can it be done? can the plate voltage be lowered?

 

[cadstarsucks]

Yes that distorted sound is what im after. I dont know why are u refering as poor sound i have an intrument amp (it has a bass guitar input) with 2EL84 finals and sounds really nice. Still can it be done? can the plate voltage be lowered?

The plate voltage is an integral part of how the tube functions. I do not recall the tube curves as I have not even contemplated them since high school.

That said, I believe there is a way to run a pentode at a lower voltage and still get the same response out of it, but the info is on my machine at work

D.

 

[Analog]

Yes that distorted sound is what im after. I dont know why are u refering as poor sound i have an intrument amp (it has a bass guitar input) with 2EL84 finals and sounds really nice. Still can it be done? can the plate voltage be lowered?

Tube amplifiers are the best sounding amplifiers in my humble Analog opinion. The human ear cannot differentiate between distortion above ~1%. Anyone saying that it can is blowing smoke - and I have the studies to prove it.

That being said, tube amps do not clip as cleanly as solid state, and thus have a different harmonic response when driven, thus giving them a softer, warmer sound. I have designed many tube power stages, and I truly believe they are superior 'sounding', but if you want to talk rote specs, they cannot match solid state amps. I vote for sound, rather than a spec sheet.

 

[kchriste]

You can (well you used to) get tubes that run with plate voltages of around 12V. I don't know if they will produce the "right" distortion though:
http://www.duntemann.com/12vtubes/12vtubesindex.htm

 

[hentai]

cadstarsucks i would apreciate if u remember me and return with some of that info
Analog i agree with u entirely. if the results are better on the osciloscope it may not tell much went it comes to music.
kchriste thx alot for the link... i'll be looking for those

 

[audioguru]

Vacuum tubes deteriorate from the moment they are turned on.
Years ago my tube amp kept needing replacement tubes to keep terrible distortion away. The output tubes lost their matching very soon. Every corner store had a tube tester and sold replacement tubes.

 

[Sceadwian]

You could always figure out how to add the proper distortion and slew rate charactoristics to a semi conductor design.

 

[hentai]

Hi thx for replies.
audioguru u r right but i'm not gonna use this for gigs or anything just for home use and i think will be a good practice
sceadwian yes i've seen some circuits claiming tube like sound but i have some tubes and i wanna use it... i guess i'll have to experiment a bit.

 

[Nigel Goodwin]

Hi thx for replies.
audioguru u r right but i'm not gonna use this for gigs or anything just for home use and i think will be a good practice
sceadwian yes i've seen some circuits claiming tube like sound but i have some tubes and i wanna use it... i guess i'll have to experiment a bit.

Like I said, use the high voltages - you're looking for the specific 'valve sound' rather than high quality - so it makes sense to do it as it's always been done, and use the valves as designed.

 

[hentai]

Sir, Yes Sir! thx for ur answers

 

[Nigel Goodwin]

You might have noticed, the older members, who come from the valve days, aren't impressed by their 'sound' - it's mostly the youngsters who seem to find their low performance somehow sounds 'better'

 

[Roff]

Here is a hybrid amp that includes a triode running on a 24V plate supply, with plate current at 0.56mA. It is includes a very thorough description and analysis of the circuit.

 

[audioguru]

iThe nput of the tube amp is 1kHz and the output is 2kHz. 1/20th of the output is added distortion.

 

[Roff]

iThe nput of the tube amp is 1kHz and the output is 2kHz. 1/20th of the output is added distortion.

Depending on the tube and the bias.
All the better for our OP. He's not trying to reproduce concert hall sound. he's building a bass guitar amp.
For a headphone amp, as this circuit was designed to be - now that's a different issue. I think I would pass on the tube amp.

 

[hentai]

Hi!
thx alot Ron!
as for the others dont worry about how is going to sound cuz ur not gonna listen to it
thx again for ur inputs

 

[cadstarsucks]

cadstarsucks i would apreciate if u remember me and return with some of that info
Analog i agree with u entirely. if the results are better on the osciloscope it may not tell much went it comes to music.
kchriste thx alot for the link... i'll be looking for those

Well I've found it, but it is only saying to double the power at a given voltage.

There are still tubes like the ones mentioned elsewhere, but I believe the only source is russian. I know they are still around because an old design here uses them on the input side to get the "tube" sound.

D.