Anyone one build something with 7591's?

[ER]

Any sound impressions? Anything comparable tone wise? Seems like they would fall somewhere between 6v6 and 6l6. Maybe a mini EL34?

I've been looking at the new JJ's and might try them out on something in the 35 watt range.

-Erik

[BackwoodsJoe]

I heard a amp at Indoor Storm in Raleigh a while back that used the 7591's. I think it was an Oldfield brand. Sounded great with plenty of low end. What I heard was 6L6ish.

[Structo]

Interesting, not familiar with that tube.

Looks like the quick specs are:
Ih 0.8A
VaMax 550v
Vg2Max 440v
PaMax 19w

Is this one of those tubes you can still get at bargain prices?

[Firestorm]

Is this one of those tubes you can still get at bargain prices?

Alas, like the 7027, this is one of those damn Ampeg tubes (I think one Fender in the mix, too), so NOS is pricey. Not as bad as the 6BK11, tho, which is gone, gone, gone.

[ER]

Yeah the old stock is pricey (no bargains here), but the new JJ's are in line with modern offerings price wise.

[Alexo]

I've been fiddling around with 7591's lately.. They are neat tubes.

From what I understand, they were developed towards the end of the gilded age, and are pretty highly evolved. They are very compact, require relatively low heater current, low bias voltage = very easy to drive, capable of a LOT of power, up to 45 watts a pair if you believe the datasheets, and they really have a clean and balanced sound. You will have no complaints about their tone, they just sound nice, although they seem to have less coloration than other types (considered a good thing at the time).

They are pentodes though, and you have to watch out for screen current - if you build a guitar amp with datasheet values for load and voltages, they will melt in no time.

The JJ's sound pretty good, but they only gave me 28 clean watts where NOS RCA gave me 36. Meh...

[boldaslove6789]

the Kalamazoo Bass 30 used 7591's and sounded great for guitar. It was a small combo but it put out about 30w. Perfect clean to scream grab and go amp but not powerful enough to kill your ears.

[skyboltone]

Commenting on Alexo here.....who was it? Skip I think. He built a 7591 cathode bias PP guitar amp with those. Swapped them out for KT-66s because (as Alexo has alluded) they were too fragile in Guitar amp mode. He said the KT-66 was tonally about indistinguishable.

Dan

[ER]

What are folks using for PI with these? I'm thinking of doing a stereo rig for recording using some old Sanui Hi-fi iron and a clean pre, something like a stereo dumbleland for home use using the 6AN8 drivers.

[skyboltone]

What are folks using for PI with these? I'm thinking of doing a stereo rig for recording using some old Sansui Hi-fi iron and a clean pre, something like a stereo dumbleland for home use using the 6AN8 drivers.

Probably pretty much a standard LTP. Take a look at a '50s bassman scheme. They were designed for 5881/6L6GB. You'll need to increase the bias resistor maybe one notch and experiment with the tail for clean/clipping tastiness. Stick a pot in there for trial.

Wait a minute. Hold the phone. 6AN8 drivers? You'll control your drive voltage there not with the PI. Use a 0 gain cathodyne PI like a Fisher or Dyna PA.

[gearhead]

65 Amps makes a 7591-based unit:
http://www.65amps.com/stonepony.html

Bought one used from Doug (Dougs Tubes). It's pretty cool.

Kinda fendery until PT distortion, and then takes on a marshallish mid range roar.

[Structo]

I see JJ makes a 7591.

Eurotubes has them for $36 a pair.

[jcat5503]

65 Amps makes a 7591-based unit:
http://www.65amps.com/stonepony.html

Bought one used from Doug (Dougs Tubes). It's pretty cool.

Kinda fendery until PT distortion, and then takes on a marshallish mid range roar.

This is an interesting amp!

Im sure its cathode bias, as most of their amps are

Any one know much about it?