Voltages too high in Rocket

[JoeCon]

I finally got around to measuring the voltages in my Twin Tube Rocket build.
Seems every one is high for the "expected" voltages. But I used an Edcor 280-0-280 xformer not a 250-0-250 so I was expecting them to be a bit high but is this too much??

V1
pin 1 128V
pin 3 .99V
pin 6 126V
pin 8 1.02

V2
pin 1 214V
pin 2 128V
pin 3 128

V3
pin 1 186V
pin 2 37V
pin 3 52V
pin 6 189V
pin 7 35V
pin 8 52V

V4 / 5 EL84
pin 3 12V
pin 7 366V
pin 8 342

B+1 375V
B+2 348
B+3 244
B+4 215
B+5 210

AC Wall 119.5
PT Secondaries 585

With a 150 Ohm cathode resistor I'm seeing 14.5 W on the EL84's.

With all of that it sounds awesome! It's clean and clear and LOUD!! Both my Tele and Strat never sounded better.

Do I need to make adjustments to those voltages or play on!!??

[xtian]

Play on, mate! Doesn't look bad.

[JoeCon]

Xtian

Thanks man that's what I thought but it's my first scratch build!

Got it's KT66 big brother lined up next!!

...Play On!

[Blackburn]

Which brand of EL84s are you running currently?

[JoeCon]

Blackburn

JJ's!
They look fine and sound great.

[M Fowler]

Looks good Joe.

I run mostly JJ tubes and no complaints from me.

Mark

[JoeCon]

Mark

I wanna thank you sir, you gave me lots of good off line advice that made this build easy and right the first time I fired it up. I don't have a lower voltage PT to compare to but the 280V Rocket you suggested sounds amazing!
Clear, clean, BIG and Loud. Not an overdrive amp at all, can do that with a pedal, but open chords sound huge and the two position boost, either a 1uF or 10uF bypass cap on V1a, give a nice push without distortion.

When you examine it it's really a simple amp with simple controls, not a lot of bells and whistles but it's that simplicity that lets the sound just come right thru beautifully. Audio purists talk about the best amp as "a straight wire with gain." That's about what this is but a musical version of it.

As you might be guessing, I LIKE IT!!

Thanks again to everyone here, you have provided inspiration to join this group of "amp hackers!" LOL....

[M Fowler]

The Rocket is a great platform for a pedal board glad to have helped.

Mark

[Blackburn]

Good to know you're running JJs! Very good candidates for running hot. How about some pics?

[Mark]

Mark what is the difference between using a transformer with 260vac and 280vac?

I'd imagine greater headroom, but there would have to be adjustments to the screen stoppers and cathode bias resistor.

I'm nearly inclined to use 270 ohm screen grid resistors over the stock 100 ohm.

[M Fowler]

Mark what is the difference between using a transformer with 260vac and 280vac?

I'd imagine greater headroom, but there would have to be adjustments to the screen stoppers and cathode bias resistor.

I'm nearly inclined to use 270 ohm screen grid resistors over the stock 100 ohm.

Tone.

[Mark]

The voltage thing is so subjective, a friend builds AC-30's and swears by 320V for a good sounding AC-30. I have played his amps and they do sound very good, in fact very much like a good vintage AC-30.

The last "real" AC-30 I tried had a larger rail, by comparison I could smell the paint burning off the valves and the amp sounded one dimensional and stiff.
Obviously there is more to good tone than raising the rail voltage. What do you get from the larger rail?

[JoeCon]

Mark and Mark,

I have a variac I could use to turn the AC power down while measuring B+1 and try a lower rail voltage and report what I hear if that would be a way to hear the differences.

But to the subjectivity issue, there are different cabs and speakers and guitars involved so those wlil contribute to the difference we hear as well as our own set of preferences for what tones we want and like.

Variac test??

[ampgeek]

Joe,
Use caution on the variac testing gig. It will need to be done in such a way that won't significantly alter the voltage on the tube heater filaments.

Cheers,
Dave O.

[JoeCon]

Dave

Thanks good catch. I have a bench supply that will work. Disconnect PS from heaters and use it to keep filaments HOT!! This is getting more complicated all the time...