7591's, how much power to expect?

[azatplayer]

Been looking thru old Ampeg schemos. I built a B15N coupe years ago with fantastic results. Used some hammond iron i had from an earlier build.
My brother uses it for guitar as well as baritone and it sounds brilliant. I added a bias vary tremolo which is also pretty cool.
Been looking at the R12R reverbarocket and also GU12 and other schemos using these 7591's/7591A's. Data says theyre about a 19watt tube, yet duncans say in AB1 they produce 45watts at about 450V plate.
WHat kinda tones do they produce? And what kinda output?
Something between a 6V6 and a 6L6?

[Phil_S]

The data sheet http://tubedata.itchurch.org/sheets/127/7/7591.pdf says fixed bias AB1 PP, Va=450, 45 watts. That is power out for two tubes.

19W is maximum plate dissipation. I don't understand the technicalities, but this is somewhat different from power out.

In any case, if you figured 19 x 2 = 38, that's actually not far from 45. I am going to guess you will not get a full 45W out of a pair.

[azatplayer]

Yeah i see Ampeg usually ran around mid high 300's with these tubes in these early guitar offerings. Thats around 6V6 volts in a tweed, but using the BFDR impedance of 6K6, they would have to be around 25-28 watts at a guess.
Could be a real sweet gigging level.
Wondering what they would sound like in a more contemporary design.

[renshen1957]

The data sheet http://tubedata.itchurch.org/sheets/127/7/7591.pdf says fixed bias AB1 PP, Va=450, 45 watts. That is power out for two tubes.

19W is maximum plate dissipation. I don't understand the technicalities, but this is somewhat different from power out.

In any case, if you figured 19 x 2 = 38, that's actually not far from 45. I am going to guess you will not get a full 45W out of a pair.

Hi,

How much power a pair of tubes can generate depends on the Plate voltage, the Screen Voltage, and the primary impedance of the output transformer and other a few factors in the circuit. The 7591 has been called half a 6550!

Using another Tube as an example, the EL 34 or its North American cousin the 6CA7, were used by Traynor was able to extract about 80 Watts clean from two 6CA7 (EL 34) in the Bassmaster YB 1A Mark Two. The Marshall Plexi would have difficulty exctracting 50 Watts Clean (and higher Watts into distortion) from an EL34.

The difference was the Plate and Screen Voltages are higher.

The 7591 tube/valve would be frequently found in Hi Fi amps, for its low distortion, a linear tube. Ampeg's use would be for its target market amps for bass players and jazz guitarists.

Best Regards,

Steve