6v6 OT

[Tone Junkie]

So I know a standard p-p 6v6 ot for a pair is 6.6k has any one used an 8k with good luck I know I can use it , but I just wanted to see if any one has used one and liked it . I started this build as a el84 build but the reality after playing a few 18 watters lately Im thinking i would probably like a 6v6 better , just seeing if I should order a new OT before I start.
Thanks Bill

[tubeswell]

8k is standard for many 6V6 fenders including BFPR and tweed deluxe

[Tone Junkie]

Thanks tubeswell thats what i wanted to hear.
Bill

[tubenit]

I use 8k on my 6V6 amps.

With respect, Tubenit

[rzenc]

I used 8K on 5E3 and 5E9-A builds.

Best Regards
Rzenc

[jojokeo]

Bill,
I've experienced some upside to the increased loading affect on tubes & trannies recently in several amps. Could I ask you to hook up the tranny in 4k and report your findings & feelings on what you hear & think compared to the 8k tap regarding headroom, tone, punch, & overall volume differences?
I'm looking for more feedback on this from others. Thanks-

[Tone Junkie]

Jojokeo I can do the same thing by running an 8ohm speaker on the 4ohm tap right or do I have that backwards 8 to 16 I seem to get those things confused.
Thanks Bill

[jeff]

Is there such a thing as a 6V6 transformer? I think using 6V6s is only part of the equation.

Isn't the impedance of the OT dependant on the B+?
Different voltages different transformer?
(doesn't a deluxe use a 6K6 and a princeton use a 8K? but the deluxe is cath biased and lower voltage than the princeton)

What I'd like to know is if you know the plate dissipation and the voltage, what's the formula for the transformers impedance?
  

[jojokeo]

Jojokeo I can do the same thing by running an 8ohm speaker on the 4ohm tap right or do I have that backwards 8 to 16 I seem to get those things confused.

Just think about the speaker being less than normal tap (8ohm into 16ohm tap) then primary impedance drops. If speaker is greater than normal impedance (8ohm into 4ohm tap) then impedance is also greater on pri Z.

What I'd like to know is if you know the plate dissipation and the voltage, what's the formula for the transformers impedance?

Pri Z = V^2/W where V is actual plate voltage squared divided by W which is the Pdiss in watts you have the otuput tubes biased at.

[jeff]

"Pri Z = V^2/W where V is actual plate voltage squared divided by W which is the Pdiss in watts you have the otuput tubes biased at."

That's the formula I've always used for SE amps.

According to the schematic a Princeton Reverb runs at 410V. If it's biased to 70% of 12W that's 8.4W.

So (410 X 410)/8.4=20011
20K doesn't seem right.

Is there a different formula for PP AB amps?

[jojokeo]

You can also use R=V/I and need to know your current. I think these are only estimates at best. As PRR says in another post - this is difficult and depends on various factors and then you use your ears for what's best. BUT crap, by that time you've already got a specific OT bought and installed. This is why I'm trying to get various feedback on others pri Z being lower than might be recommended. Lately I'm experiencing a lower load is giving me more of what I like.

You don't need to bias a SE amp so low. You can go up as high or higher than Pdiss as long as the tube doesn't redplate.

[jeff]

I hear ya, The sound is what counts.

[PRR]

> for SE amps. .... If it's biased to 70%

"70%" is for FIX-bias amps. The maximum power is not limited by idle dissipation. Loading is a multi-step analysis.

Self-bias (SE is usually self-biased), you only get out what you put in, actually half, actually less. So for max power for the tube-buck you must bias to 99% Pdiss. Maybe 120% if you are brave.

Plagiarize. The tube-manual conditions DO work. Two 6V6 can run around 300V at 8K or 10K for a happy 10W-14W output. The Fender amps do work, for post-1940 6V6es, with gitar-amp reliability.