I am going to build a pre-amp from a triode connected EL84...
What is a good Va and Ia to run it at?
Probably use a CCS or mu-follower configuration with either pentode or SS.
low voltage 100-150v ?
Thanks!!!
maybe 120v 10mA 4v bias..
?
What is a good Va and Ia to run it at?
Probably use a CCS or mu-follower configuration with either pentode or SS.
low voltage 100-150v ?
Thanks!!!
maybe 120v 10mA 4v bias..
?
because....
well because i want to.
🙂
I want to use current production tubes mainly.
any other ideas?
besides the 6H30 which sucks.
well because i want to.
🙂
I want to use current production tubes mainly.
any other ideas?
besides the 6H30 which sucks.
Re: because....
Hello ,
How about the 12B4A ? Pro's : Look nice , cheap , plentiful , good sounding . Cons : can be microphonic but saying that , at $2 a throw on Ebay.... Plenty of other candidates along the same lines : 6S19 , 2C50 , 6BX7 , CV1884 , A2293
cheers 🙂
316a
AudioGeek said:
Hello ,
How about the 12B4A ? Pro's : Look nice , cheap , plentiful , good sounding . Cons : can be microphonic but saying that , at $2 a throw on Ebay.... Plenty of other candidates along the same lines : 6S19 , 2C50 , 6BX7 , CV1884 , A2293
cheers 🙂
316a
In current production triodes, JJ's ECC99 is definitely worth trying.
BTW, what sort of source and what sort of power amp are you going to mate with the line stage? Be alert for a possible "hair trigger" volume control.
BTW, what sort of source and what sort of power amp are you going to mate with the line stage? Be alert for a possible "hair trigger" volume control.
AudioGeek said:
I'm thinking about 125v on the plate with a -4 bias on the grid @20mA. You would need a 200 ohm cathode resistor. the problem is you would need to use a CCS on the plate or you would need to use a plate choke because a plate resistor ain't gonna get the job done. With a CCS or a choke it may end up being a killer linestage. Here is a link to a alternative plate load that is dirt cheap at digikey. It will take some tweaking but it's definately doable. :
http://www.pmillett.addr.com/current_source.htm
You will need to use a heatsink with the IXYS current source. Also you have to understand that when using a solid state CCS you have to bias the tube with the plate to ground voltage drop in mind. It looks like you would need a 150 ohm resistor on the current source for 20mA. You might try a 500 ohm 5 watt resistor in parallel with a 500 ohm 2 watt pot so you can just dial in the current. If you build a supply that will provide 40mA at 250 volts all you would need to do is adjust the pot until you got a 125v drop from plate to ground across each tube and viola, you have a EL84 linestage. Strange but interesting🙂 🙂 . Cheers.
hehehe
I threw together a linestage with some 6BQ5's...
120v on anode, 20K plate resistor, 4v bias.
gain is good.
FLAT response to about 35Khz...
smokes my 6H30 pre-amp.
no noise really.
VERY low distortion.
I am going to convert this to a mu stage with SS CCS and a regulated power supply.
Any thoughts on the power supply???
Thanks!
I threw together a linestage with some 6BQ5's...
120v on anode, 20K plate resistor, 4v bias.
gain is good.
FLAT response to about 35Khz...
smokes my 6H30 pre-amp.
no noise really.
VERY low distortion.
I am going to convert this to a mu stage with SS CCS and a regulated power supply.
Any thoughts on the power supply???
Thanks!
You still using the el84 as a line stage? I’ve got a perfect setup to try that with regulated HV B+.
Can you share some schematic details? I do have a pair pair of 5k OTs to load them.
Cheers,
Greg
Can you share some schematic details? I do have a pair pair of 5k OTs to load them.
Cheers,
Greg
I have to say that I found useful the necroposting.
The reason is simple: the user wasn't there when the argument was discussed, the same way most of us weren't there when RCA (Mullard, Telefunken, etc...) discussed and discovered what we are talking about here. But we still talk about it.
When I read something, even if it's 10 years old, most probably has been written by someone that is still here around, and can better explain some details, and this can be the trampoline to new ideas. Or others can do.
The reason is simple: the user wasn't there when the argument was discussed, the same way most of us weren't there when RCA (Mullard, Telefunken, etc...) discussed and discovered what we are talking about here. But we still talk about it.
When I read something, even if it's 10 years old, most probably has been written by someone that is still here around, and can better explain some details, and this can be the trampoline to new ideas. Or others can do.
You bring up a good point and my response is that many of us (from 16 years ago ) are thankfully alive and well. Also, someone who was not part of the original thread may see this and chime in with an answer.
It's the old adage "ask and you shall receive" idea 😉
Audiogeek was last on the site days ago, and started a new thread Oct 24. I don't see an issue with a question to an active member.
I am interested in the OP's response too, considering that I have quite a few 6BQ5s and 8BQ5s of several mfrs.
I am interested in the OP's response too, considering that I have quite a few 6BQ5s and 8BQ5s of several mfrs.