Tried EL34's in place of 6L6's

[mat]

What I'm missing ? The 6L6's were biased at -40mV(A) (DMM connected to back panel bias points (1ohm resistor method). I swapped to EL34's and the meter shows (+)2mV(A) ??

I have the pin 1&8 tied together of the octals and then they go via 1ohm resistors to ground.

I did not know that bias can differ so much depending of the tube

[llemtt]

usually you have at least 10v difference between 6L6s and EL34s

Teo

[dogears]

Normal....

Just crank em up!!

Also, try the 6L6 a little cooler than 40ma

[mat]

Normal....

Just crank em up!!

Also, try the 6L6 a little cooler than 40ma

I have first to check if my bias can go to -40mV(A) - -50mV(A) with the EL34's because with 6L6/40mV(A) setting it is with EL34's at +2mV(A) !!

Would You think about -45mA would be better to 6L6's ?

[Bob-I]

Normal....

Just crank em up!!

Also, try the 6L6 a little cooler than 40ma

Would You think about -45mA would be better to 6L6's ?

No, wrong way. Try them at 33-35ma.

[BobW]

I tried a pair of EH EL34s last night, and immediately noticed an increase in the upper midrange. I'll need to crank it up tonight and give it a workout before I decide. B+ = 465V, bias at 31mA.

[mat]

I tried a pair of EH EL34s last night, and immediately noticed an increase in the upper midrange. I'll need to crank it up tonight and give it a workout before I decide. B+ = 465V, bias at 31mA.

I did put the EL34's in (bias 49mA, B1 474V) and made a clip awailable on thread: https://tubeamparchive.com/viewtopic.ph ... c&start=30

I like them alot

[mat]

Normal....

Just crank em up!!

Also, try the 6L6 a little cooler than 40ma

Would You think about -45mA would be better to 6L6's ?

No, wrong way. Try them at 33-35ma.

DOH! I think I'll never learn this one

[BobW]

I did put the EL34's in (bias 49mA, B1 474V) and made a clip awailable on thread: https://tubeamparchive.com/viewtopic.ph ... c&start=30

That's 23W per tube at idle! Max dissipation per Svetlana EL34 is 25W. They won't last long.

[mat]

I did put the EL34's in (bias 49mA, B1 474V) and made a clip awailable on thread: https://tubeamparchive.com/viewtopic.ph ... c&start=30

That's 23W per tube at idle! Max dissipation per Svetlana EL34 is 25W. They won't last long.

I'll put them immediatly to 30 something.. (..searches the biasing method prints..)

EDIT- better sound.. huh, hope I did not take too many hours of their live

[dogears]

Mat,

Just measure the current across the 1 ohm to ground on pin 8! Same as a 6L6. Set them at 30-32ma for starters.

I did put the EL34's in (bias 49mA, B1 474V) and made a clip awailable on thread: https://tubeamparchive.com/viewtopic.ph ... c&start=30

That's 23W per tube at idle! Max dissipation per Svetlana EL34 is 25W. They won't last long.

I'll put them immediatly to 30 something.. (..searches the biasing method prints..)

[mat]

Just measure the current across the 1 ohm to ground on pin 8! Same as a 6L6. Set them at 30-32ma for starters.

Yes, that much I know, but I was sure when I searched for the bias current of the EL34's on the forum I found suggestion to put them at 50mA, but that depends always also of the B+..
They are now 31.5 and do sound smoother on the clean channel. I cannot crank the OD channel any more today

[dogears]

Is your amp individual bias or both tubes at once?? If it is both at once, I'd set to 60ma-65ma


If it is seperate tube adjustments, then you are good now.

Just measure the current across the 1 ohm to ground on pin 8! Same as a 6L6. Set them at 30-32ma for starters.

Yes, that much I know, but I was sure when I searched for the bias current of the EL34's on the forum I found suggestion to put them at 50mA, but that depends always also of the B+..
They are now 31.5 and do sound smoother on the clean channel. I cannot crank the OD channel any more today

[mat]

Is your amp individual bias or both tubes at once?? If it is both at once, I'd set to 60ma-65ma

It is individual bias

If it is seperate tube adjustments, then you are good now.

Ok, huh Luckily I have summer holiday now. I must study the biasing of the amp a lot more.

[BobW]

Well after cranking the amp with EL34s installed, I then tried a combo of 1 6L6 (Winged C) and an EL34 (EH). I liked the tone of the mixed set, and here's what I have concluded:

6L6 pair cleanest, Less overdrive
EL34 pair brightest, more upper midrange and overdrive (maybe due to EL34 gain increase)
6L6/EL34 pair more upper midrange and more overdrive (maybe due to asymmetrical clipping).

I know these are ambiguous terms, so this weekend, I'll try to scope out the waveforms w/sine wave input and capture them on a digital scope.