D-type with 4 - 6v6 Txer question

[danotron]

I just built a d-style amp that will run 4 - 6v6 tubes. I have a matched quad of JJ's.

The power transformer I used is a Hammond 290EX. It gets very hot. I am guessing the problem is that the amp is drawing to much heater current.

4 - 6v6 (4x0.65=2.6 amps) and 3 - 12AX7 (3x0.3= 0.9 amps) draw about 2.6+0.9=3.5 amps

The transformer is rated at 3.15 amp. Could this be my running hot problem.?

When I run a pair of 5881, there is no problem with heat.

I would rather run the 4x6v6..I love the tone.

To fix this problem (if it is the problem) I was thinking of running the preamp tubes from a different transformer. I was thinking a Hammond 266JB6. This would lighten the current draw on the PT for the 4- 6v6 by 0.9amps.

Does my thinking make sense?
Do you think the 266JB6 is the correct txer for the preamp tubes?

Thanks

Dan

[10thTx]

I thought four 6V6's would be closer to 1.8 amp?

http://tdsl.duncanamps.com/show.php?des=6V6GT

With respect, 10thtx

[danotron]

The data sheet says .5A but I am finding articles that say .65A.

http://billmaudio.com/wp/?page_id=370

[amplifiednation]

The data sheet I just pulled shows .45A

How hot do you have it biased?

[danotron]

biased at %70 but I'll double check that today....tube a JJ 6V6 they draw a bit more

[mhartman]

This might help:

http://www.dreamtone.org/Calculate_Current_Form.htm

[FUCHSAUDIO]

Just treat 4 6V6 like 2 6L6 (same power and output iron) and you will be fine....grid bias voltage a little less, thats it !

[danotron]

Yes..that calculator says 4-6v6 and 3-12AX7 draws 4.5A......way over my PT rating of 3.15A.....according to that page 4-6v6 draw 3.6A...do you think it's correct?

My data sheet says 2.6A.....

[mhartman]

Yes..that calculator says 4-6v6 and 3-12AX7 draws 4.5A......way over my PT rating of 3.15A.....according to that page 4-6v6 draw 3.6A...do you think it's correct?

My data sheet says 2.6A.....

I'm thinking that the calculator is wrong. 3.6A is around what a 4x6L6 would pull, not 4x6V6s.

[Zippy]

Why not either measure the resistance of your heater circuit and voltage across the heaters, and calculate the current draw? Or/and insert your ammeter and directly measure the current in the heater leg?

Yeah, I know that talking about tables is so much more fulfilling - even if less accurate.

[Teleguy61]

Just treat 4 6V6 like 2 6L6 (same power and output iron) and you will be fine....grid bias voltage a little less, thats it !

Exactly!
Bassman type PT is fine for a 4X6V6 amp.

[10thTx]

My experience is that Hammond trannies seem to be over built. I've used a number of Hammond PT's and have been very happy with them.

My suggestion is check the voltage on the heaters with four 6V6's. And then check with two 5881/6L6's. IF the voltage is pretty much the same, then I wouldn't worry about it.

You can also check the heater voltage with two 6V6's and then four 6V6's. Does it change/drop much? If not, then I wouldn't worry about it.

IF the head & four 6V6's are hanging upside down ....... and the 4 tubes are reasonably close to the PT, then I'd expect it to get hot.

With respect, 10thtx

[xtian]

"Hot" is a pretty vague term. Can you keep your hand on it for 10 seconds? ("Carry the PT across the room between your wrists, Grasshopper.")

[danotron]

I will do some measuring tonight and report back. Thanks or all the great advice!

[tubedogsmith]

What is your wall voltage there and what is the trannie spec'd for?