OT for 6550

[mauiboy81]

Aloha, Aloha, Aloha fellow tweakers.

I am finishing up a build based on #124 (sorta). See, I am only doing the clean section, no od. Crazy I know but it is what it is. I also am only using 2 power tubes for lack of space.

My OT is a Heyboer tweed bassman type with 2/4/8 so naturally i began with the thought of using 2 6l6gc's but naturally i am starting to question that and am wondering if I would be able to use 6550's instead. Can my OT handle it?

My PT is Heyboer with specs as follows:
-710v @ 300mA
-50v bias tap
-6.3v @ 7A
-6v @ 4A

Any thoughts are welcome. thanks

Nick

[mauiboy81]

Also, knowing i have no od would you recommend the rock/jazz or deep switch?

[Bob-I]

I'd be concerned about that OT. The Tweed bassman OT was underspec'd for the 5881's (who would EVER play that loud). I'd stick with the 6L6's myself, it'll be plenty loud, plus the 6550's tend to be a bit stiff when cranked to breakup where 6L6's get very sweet.

I have the Jazz/Rock on 2 of my amps but I always play in Rock mode. I can see the use though. In Jazz position with the bass up above 3:00 it has that very typical 1950's mellow jazz tone.

[talbany]

Aloha, Aloha, Aloha fellow tweakers.

I am finishing up a build based on #124 (sorta). See, I am only doing the clean section, no od. Crazy I know but it is what it is. I also am only using 2 power tubes for lack of space.

My OT is a Heyboer tweed bassman type with 2/4/8 so naturally i began with the thought of using 2 6l6gc's but naturally i am starting to question that and am wondering if I would be able to use 6550's instead. Can my OT handle it?

My PT is Heyboer with specs as follows:
-710v @ 300mA
-50v bias tap
-6.3v @ 7A
-6v @ 4A

Any thoughts are welcome. thanks

Nick

I would advise against it as well..Tweed Bassmans were rated
60 watts at less than 5% distortion.
Frequency Response: With optimum tone control settings +1 dB 20 to 20,000 cycles per second at 50 watts.
2 6550's @ 450V will dissipate close to 75 watts and 40 at idle.. Seriously pushing the envelope on that OPT transformer..

Tony

[mauiboy81]

Thanks guys,
I figured I would be pushing it with 6550's so will stick with 6l6gc's.
I got it working last night and it sounds great. The only 6l6's i could get on maui are the Groove Tubes 6l6-ge and I couldn't wait to order any others so that is what's in there now.
Now I'm adjusting the dropping string to get proper voltages.

[mauiboy81]

What is it that determines an OT's power rating? Is is the gauge of wire or the insulation used or somezing like zat?

[talbany]

Everything contributes..But the main ones are Wire size, insulation type and thickness ..interleaving method and of coarse core size to dissipate heat..Larger core = more laminates= smaller magnetic field= less chance of magnetic coupling..

Tony