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7591XYZ tube size

MickeySmile

MickeySmile

Well-Known Member
I Just acquired the home brew amp and it uses four 7355 tubes in output. Just want to try out this 7591XYZ tube but worry about bottle size. Don't want to buy and can not put them in the amp. Has anyone own this tube? Could you give me the diameter size of the tube. Thank you much for your help!
 

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The tubes are the same size; but as I remember there is a tiny dif. in how the screen grids are connected in the socket.
 
Biggest difference is height. They're about 1/2" taller than original 7355s, which can sometimes cause a problem with fitting the top cover back onto some amps. Diameter hasn't been a problem yet. And the last Bogen amp I put some 'XYZs in was as tightly-packed as that amp, easy. They don't seem to run that hot, either.

The only connection issue that sometimes comes up, is that pin 4 of the 7591 is connected to pin 8 inside the tube, where it is NOT in the 7355. This just means that anything that happened to be connected to pin 4 (i.e, if pin 4 was being used as a connection/terminal point for anything), that would have to be moved off of pin 4. This has not been the case for anything I've worked on so far (Bogen and other companies I've seen so far, have not used pin 4 for anything), but it COULD happen... you need to check for it. Just check to see if anything is soldered onto pin 4, on the bottom of the 7355 sockets...

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Regards,
Gordon.
 

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cademan said:
This is just me, but I would stay with the 7355. It's a good tube!
Click to expand...

Yes, I agree with you. The 7355 tube set in the amp I borrow from another HK TA260 amp therefore I still need for new set. The matched quad of 7591XYZ is 48 bucks, so tempted to buy them :D
 
They certainly work well. Basically, the 7591XYZ is a repinned 6L6... and it's hard to go wrong with a 6L6. Especially when they are virtually IDENTICAL in every parameter, to the 7355...

Regards,
Gordon.
 
"Pin 4 connected to pin 8 on the 7591"---On the Harman Kardon A500 and A50K amps, (7355 tubes), pin 4 on all the output sockets is used as a tie point, so you would get 'mutch spitzersparken' if you directly substituted a 7591XYZ. I didn't trace out the wiring, but can't believe it would be good.
Tom
 
If something is soldered to pin 4 on the amp and you're not comfortable soldering you can simply use a dremmel tool with a cut off wheel and zip pin 4 off the XYZ tubes.
 
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