New Rectifier Tubes Pulling massive current.

[Intergalactic Tourister]

I don't know what your plate voltage is with the 6L6GC's installed, but assume it's high 400's or around 500V, since you had 530V without any power tubes installed.. 48mA @ 500V is like 24W dissipation. Too hot for 6L6GC's. 35mA @ 500V plate would be around 17.5W dissipation, and more than adequate. I assume your bias meter can measure both plate (cathode) current and plate voltage.

Is this a custom build amp, or a commercially built amp? I recall the statement 'Fender-like' in the opening thread. You also have the option of using some 1N4008 rectifier diodes in place of the rectifier tube. Your plate voltage would be higher than with either a 5U4GB or 5AR4, but it would take the rectifier tubes out of the variables.

Thanks,

Bias meter measures plate current only.

So, I adjusted my bias pot range... now allows the JJ6L6GC to operate between 15w and 20w dissipation (I get about 470v @ 33ma, 15w, at the coldest setting.)
Its been repainted so I dont know what its is. It could have been an old kit.

I'll keep the rect tube in for now.

[Intergalactic Tourister]

Who cares? Itīs a DEAD tube.
Why would you want to calibrate your amplifier with a broken part?

Just use the modern, working parts, calibrate following the standard procedure everybody uses and call it a day.

What do you mean?

The tube is DEAD? The old tube works fine in the other amp... almost identical to the new tube.

I don't want to calibrate with a broken part. Here's my quote: "I'm also thinking a previous owner may have added this bias pot and biased this amp WITH the (faulty?) Tung Sol. I'm going to go ahead and add the 30k or so to the bias pot so the new rect tubes are in range."

Yes, I'm using modern new working parts. New rect tube and new power tubes.

[pdf64]

The tube should have 2 functioning diodes, the likelihood is that it now only has 1 functional diode.
Yes it still 'works' but it's performance is massively compromised.
Measure the other amp's power output with the old and a new rectifier and see if it truly does work fine with the old rectifier (ie rather than just idle cold).
Do the test Enzo outlined in post #43.

[J M Fahey]

What do you mean?

The tube is DEAD? The old tube works fine in the other amp... almost identical to the new tube.

I don't want to calibrate with a broken part. Here's my quote: "I'm also thinking a previous owner may have added this bias pot and biased this amp WITH the (faulty?) Tung Sol. I'm going to go ahead and add the 30k or so to the bias pot so the new rect tubes are in range."

Maybe you donīt see a contradiction between "works fine" and "faulty"?
Weird

Yes, I'm using modern new working parts. New rect tube and new power tubes.

Maybe so, but you are asking about the old/dead/broken/faulty parts

what you think might happen when rebiased @ -50v and I plug in the Tung Sol?

and Iīm answering to *that*.
I even underlined the Tung Sol bit, so, why would you think it applies to the new stuff?
I am perplexed.

EDIT: and rereading this I see you still use the wrong assumption:

add the 30k or so to the bias pot so the new rect tubes are in range."

you still assume that bias, somehow affects "what rectifier tubes pull" like in your very first post (and later ones) and thread title itself.

Read this until it sinks:
* LOAD pulls current from the PSU
* Rectifiers SUPPLY such current on demand
Cause and effect, donīt confuse them.

[Intergalactic Tourister]

Maybe you donīt see a contradiction between "works fine" and "faulty"?
Weird

Maybe so, but you are asking about the old/dead/broken/faulty parts and Iīm answering to *that*.
I even underlined the Tung Sol bit, so, why would you think it applies to the new stuff?
I am perplexed.

EDIT: and rereading this I see you still use the wrong assumption:

you still assume that bias, somehow affects "what rectifier tubes pull" like in your very first post (and later ones) and thread title itself.

Read this until it sinks:
* LOAD pulls current from the PSU
* Rectifiers SUPPLY such current on demand
Cause and effect, donīt confuse them.

Maybe you don't see the contradiction, from my standpoint, of the tube 'working fine' in one amp and appearing faulty in another amp? Maybe I didn't know if the tube was good or faulty? What is your point?

So what if I ask about a faulty part?

Please quit taking my post out of context. Go back and read. Context being that if I bias my amp with the new rect tube... then plug in old rect tube, amp should be very cold. Why can't I ask? As some have responded, it appears one side of the tube is bad. Well, I didn't know that. I just wanted to know why the old tube was doing that. Now I know- one side went bad.

If you read my earlier posts, yes, I had to correct/edit myself. So what? It was a mistype. Read the very sentence before the one you quote me on... you would know that it was a mistype ("I'm also thinking a previous owner may have added this bias pot and biased this amp WITH the (faulty?) Tung Sol."). I know that I'm not biasing the rectifier tube or whatever. Again, my fault for the mistype... but come on already.

So I'm done with this thread. Amp seems fine. Tube seems bad. Thanks.