New build Complete: 45W, four 6V6, non-HRM

[ER]

You can use an LED for bias on preamp tubes, or a AA battery for that matter, anything that passes ~-1.5v, works well in some hi-fi apps. But I don't think it's biasing per se on split power tubes like that.

Just for clarification, splitting a 4 tube power section doesn't change the primary impedance on the OPT, it stays the same, so for 2 tube 1/2 power mode it will be too light of an impedance load on the power tubes. But since a transformer is simply a step-up/step-down device based on winding ratios, by changing the secondary (or speaker load) it will reflect back a higher or lower load to the primary. So like structo said, if you plug in an 8 ohm load to the 4 ohm winding, or a 16 ohm to the 8 ohm winding, you should be good with 2 tubes pulled. It will probably work just leaving it as is but the tubes won't be operating optimally power-wise and won't last as long.

When is someone going to build a 4x7591 SSS?

-Erik

[Structo]

What does a 7591 bring to the table?

Is it because it is more high fidelity?

[groovtubin]

What does a 7591 bring to the table?

Is it because it is more high fidelity?

sorry ta break in, used x4 in a HRM twin trannies when i didn`t know JACK @ these amps, but it produced a really nice milky fat OD nonetheless, my how times have changed since then!

peace, jim

[ToneMerc]

Done deal and topped off by another fine cab by Taylor.

TM

[Structo]

Looks real nice TM.

BTW, what is your new avatar?

[dcribbs1412]

Congrats on another stunning build TM
nice looking cab also

One of these days I gotta pull the trigger on one of Taylors cabs


Darin

[ToneMerc]

BTW, what is your new avatar?

Twin turbo SBC, I gotta mount an external oil pump on it. Although I would rather it be a dry sump.

TM

[amplifiednation]

TM, very nice with the cream knobs!

That engine is insane.

[ER]

Love the wheat grill cloth, makes me miss my brown vibroverb. I'm looking at that or cane (ala boogie) for my walnut twin combo style cabinet.

[Structo]

SBC as in, Twin turbo Small Block Chevy?

What kind of car is it and do you race it?

[ToneMerc]

SBC as in, Twin turbo Small Block Chevy?

What kind of car is it and do you race it?

Yep, 76mm twins with 20lbs of boost, if setup right should easily make 1600HP@8000 on race gas and only have to check valve springs between rounds. It's a new car being built, but once upon a time it was a 70 Camaro. Now the only thing that remains is the steel roof and rear quarters, everything else is glass.

No plans as of yet, I would have to get recertified and buy all updated fire protection gear.

TM

[dreric]

Another great build!

TM has cool toys!

Eric

[M Fowler]

I would love to hear the waste gates dumping on this bad boy

Mark

[marshamps]

Apparently the two 10K resistor half power approach doesn't change the primary impedance. A least that is what the TUT bibles would indicate. Unless I misunderstand mr. O'connor, which is possible

[jelle]

What's the claim? They don't fully switch off?