substitution for 7355

sweet · 29th December 2005, 04:10 PM

I have a HK A500 and not happy with the limited supply of 7355 tubes. Can I substitute 7355's with 7591 and how much would I have to motify or is there a better question I should be asking or a better tube.
Thanks Steve

Giaime · 29th December 2005, 06:21 PM

I think you can replace them with 7591 without trouble. Please take note that in 7355 pin4 isn't connected, but many datasheets on the 7591 show pin4 connected to the screen grid. So remove any component or wire that's using pin4 as a tying point.

Tom Bavis · 29th December 2005, 11:24 PM

7591 is a good replacement, but bias will have to be adjusted, as they will be at cut-off with the bias for a 7355.

The Sovtek 7591XYZ is a rebased 6L6, and it's a perfect plug-n replacement if it fits... it's the same size as EH 7591, but doesn't require rebiasing. Check pin connections as mentioned...

sweet · 30th December 2005, 10:49 AM

I thank you all for the info. I spent alot of time restoring this amp.
I am now planning on fixing it up cosmetically. I will be using brass plate for chassis and getting rid of some of the pots and unnessisary junk. Rearranging layout and just making it look pretty so my wife will allow it in the living room. I have connected up to my Marantz D77's. I was into the 70's amps and recievers (SS). I have a storage shed full of Marantz's Pioneers and Sansui's along with 70's Speakers. My wife as commented and said this was the very first amp she listened to and could really tell the differances. So she really wants me to make this pretty. After I fix this up cosmetically, I have purchased a set of mid horns and tweeter horns so I am going to try my hand at a set of speakers.
Thanks Steve

29th December 2005, 04:10 PM	#1
sweet diyAudio Member Join Date: Dec 2004 Location: Carolinas	substitution for 7355 I have a HK A500 and not happy with the limited supply of 7355 tubes. Can I substitute 7355's with 7591 and how much would I have to motify or is there a better question I should be asking or a better tube. Thanks Steve

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29th December 2005, 06:21 PM	#2
Giaime diyAudio Member Join Date: Oct 2004	I think you can replace them with 7591 without trouble. Please take note that in 7355 pin4 isn't connected, but many datasheets on the 7591 show pin4 connected to the screen grid. So remove any component or wire that's using pin4 as a tying point.

29th December 2005, 11:24 PM	#3
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	7591 is a good replacement, but bias will have to be adjusted, as they will be at cut-off with the bias for a 7355. The Sovtek 7591XYZ is a rebased 6L6, and it's a perfect plug-n replacement if it fits... it's the same size as EH 7591, but doesn't require rebiasing. Check pin connections as mentioned...

30th December 2005, 10:49 AM	#4
sweet diyAudio Member Join Date: Dec 2004 Location: Carolinas	I thank you all for the info. I spent alot of time restoring this amp. I am now planning on fixing it up cosmetically. I will be using brass plate for chassis and getting rid of some of the pots and unnessisary junk. Rearranging layout and just making it look pretty so my wife will allow it in the living room. I have connected up to my Marantz D77's. I was into the 70's amps and recievers (SS). I have a storage shed full of Marantz's Pioneers and Sansui's along with 70's Speakers. My wife as commented and said this was the very first amp she listened to and could really tell the differances. So she really wants me to make this pretty. After I fix this up cosmetically, I have purchased a set of mid horns and tweeter horns so I am going to try my hand at a set of speakers. Thanks Steve

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