EL34 biasing for an idiot (e.g. me)

Bob · Post by **Bob** » Mon Jun 25, 2007 11:48 pm

Yeah... we *just* figured that out...the way the numbers are on this socket is really confusing...

So just pull that jumper... replace w/ the resistor.

It looked totally wrong to me... now it makes more sense.

tfrost33 · Post by **tfrost33** » Tue Jun 26, 2007 3:12 am

just so you all know, we got the 800 problem figured out, retubed and biased and the amp sounds amazing. thanks everyone!

Bob · Post by **Bob** » Tue Jun 26, 2007 3:22 am

We got the 900 rocking too, though it was a totally different beast and we had to kind of guess, as the above described method didn't seem to apply.

Fuck 900s anyway... the 800 smoked it.

toner · Post by **toner** » Tue Jun 26, 2007 3:31 am

Bob wrote:...Fuck 900s anyway... the 800 smoked it.

Well, yeah, I'd have to agree with you on that.

I just listened to a couple of your songs and you guys need some work. Just kidding!

My first impression was "Ramones meets Motley Crue". Good stuff!

Glad everything worked out.

PCollen · Post by **PCollen** » Tue Jun 26, 2007 12:28 pm

[quote="rockstah"]pin 1 and pin 8 are tied together and the 1 ohm resistor runs from pin 1 to ground.[/quote]

RS:

If using EL34's, isn't it recommended to have pin 1 (suppressor grid, g3) grounded directly, and have the 1 ohm resistor between pins 1 and 8 ? Do you leave the 1 ohm resistor in the circuit after biasing, or switch it out ?

rockstah · Post by **rockstah** » Tue Jun 26, 2007 12:41 pm

pin 1 and pin 8 are tied together pin 1 runs to ground. this is how they come from the factory. we remove the ground wire from pin 1 to ground and put a resistor in its place leaving pins 1 and 8 tied together.
what is all the confusion here? the resistor stays in place. no switches.

Bob · Post by **Bob** » Tue Jun 26, 2007 4:26 pm

toner wrote:
Bob wrote:...Fuck 900s anyway... the 800 smoked it.
Well, yeah, I'd have to agree with you on that.

I just listened to a couple of your songs and you guys need some work. Just kidding! My first impression was "Ramones meets Motley Crue". Good stuff!

Glad everything worked out.

Thanks... those first two songs in our myspace link are metro JTM45s. The song from Blacktop is an 87 100w 800 and a 78 100w JMP.

Even though this 800 I was working on smoked that guy's 900, they still both can't hold a candle to our JTMs.

tfrost33 · Post by **tfrost33** » Tue Jun 26, 2007 7:08 pm

rockstah wrote:pin 1 and pin 8 are tied together pin 1 runs to ground. this is how they come from the factory. we remove the ground wire from pin 1 to ground and put a resistor in its place leaving pins 1 and 8 tied together.
what is all the confusion here? the resistor stays in place. no switches.

No confusion at all anymore Rockstah! For us it was more wanting to be sure we understood everything. Being it was the first time both of us had peered into an 800, we justed wanted to be sure. But your method worked perfectly and is really VERY simple. Thank you!

PCollen · Post by **PCollen** » Wed Jun 27, 2007 9:14 am

[quote="rockstah"]pin 1 and pin 8 are tied together pin 1 runs to ground. this is how they come from the factory. we remove the ground wire from pin 1 to ground and put a resistor in its place leaving pins 1 and 8 tied together.
what is all the confusion here? the resistor stays in place. no switches.[/quote]

It's not a matter of confusion, or not knowing the stock configuration. The question was about inserting the 1-ohm resistor such that BOTH suppressor grid and cathode are "influenced" by the current flowing through, voltage dropped across , the 1-ohm resistor during playing as they will be with the resistor tied between pin 1 and ground. With the resistor between P1 and P8, ONLY the cathode is influenced...the suppressor grid (P1) is clamped to ground.

It probably doesn't matter......fugetabowdit.

rockstah · Post by **rockstah** » Wed Jun 27, 2007 9:22 am

it can go either way. in fact in a discussion with john suhr recently he asked Kevin O'Connor and he stated the resistor can go between pin 1 and pin 8 and pin 1 to ground. so either way u want to do it.

toner · Post by **toner** » Wed Jun 27, 2007 2:08 pm

+1 It's probably a non-issue. 'nuff said, now play some music!

raindropz · Post by **raindropz** » Wed Sep 24, 2014 6:41 am

I was not aware that if we use the transformer shunt method OR if we buy a bias probe, we don't need to install the 1 ohm resistors. I was confused in this part as I am using the transformers to Review OmniTech Support . Thank you.

bill bokey · Post by **bill bokey** » Fri Sep 26, 2014 12:00 pm

toner wrote:
Bob wrote:What wattage and voltage resistor?
1 or 2 watts is fine.

Do these HAVE to be 1W or 2W ? Isn't 0. 6w enough ? There's hardly any current so what's the need for a 1W resistor ?

neikeel · Post by **neikeel** » Fri Sep 26, 2014 1:48 pm

bill bokey wrote:
toner wrote:
Bob wrote:What wattage and voltage resistor?
1 or 2 watts is fine.
Do these HAVE to be 1W or 2W ? Isn't 0. 6w enough ? There's hardly any current so what's the need for a 1W resistor ?

Yes - can also act as fuse if you get a short

bill bokey · Post by **bill bokey** » Fri Sep 26, 2014 4:05 pm

Damn ! I've just ordered 100 0.6W metal film resistors !

Metropoulos Forum

EL34 biasing for an idiot (e.g. me)

Re: EL34 biasing for an idiot (e.g. me)

Re:

Re: Re:

Re: EL34 biasing for an idiot (e.g. me)