# 7591 VS 6L6



## AWC (Mar 31, 2008)

I have a 68 Ampeg that is spec'd to have 7591 output tubes but has 6l6's instead. Why would this be, what is the draw-back/benefit? Is it a problem?


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## spydertune (Sep 9, 2005)

AWC said:


> I have a 68 Ampeg that is spec'd to have 7591 output tubes but has 6l6's instead. Why would this be, what is the draw-back/benefit? Is it a problem?


A 6L6GC is roughly equivalent in terms of power to a 7591. 7591's were more expensive too and usually used when clearance was an issue in the amplifier chassis. I would bet the conversion was done when it was very hard to find 7591's. That isn't the case now and you might want to go back to the original. I did a quick search (.....ahem.....) and found this -

6L6GC vs. 7591


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## AWC (Mar 31, 2008)

spydertune said:


> A 6L6GC is roughly equivalent in terms of power to a 7591. 7591's were more expensive too and usually used when clearance was an issue in the amplifier chassis. I would bet the conversion was done when it was very hard to find 7591's. That isn't the case now and you might want to go back to the original. I did a quick search (.....ahem.....) and found this -
> 
> 6L6GC vs. 7591


I got your ahem right here, buddy. Thanks. I found my answer after spoonfeeding failed


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## chad (Jun 30, 2005)

You will want to obtain the schematics and go back to 7591's. I have never liked the 6l6/5881 in place of a 7591.

Sovtek sold the 7591XYZ for a long time that came as a kit, it was essentially a 6l6 with the base wired different and came with a cathode resistor to replace. It was not ideal. Now Electro-Harmonix (still Sovtek) sells a new production 7591 as does JJ Tesla. I have heard good things about both although I can usually find them NOS. I did not care for the sound of the 6l6 in a 7591 circuit, it has too many different characteristics.

7591's 









Sylvania 6U8 driven, Telefunken diamonds on the front porch


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## spydertune (Sep 9, 2005)

AWC said:


> I got your ahem right here, buddy.




(lolz)


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## spydertune (Sep 9, 2005)

chad said:


> Sylvania 6U8 driven, Telefunken diamonds on the front porch


Hard to tell what Scott that is, the knobs I can see are throwing me.


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## chad (Jun 30, 2005)

It's a 299C, it was produced during the line changeover from the C to the D, it does not match either schematic and even has a little 229 spice thrown in for good measure. 

It baffled a bunch of us for a while as to what the beast was, after hashing it out for a while on the HH Scott forum this conclusion was made, no other comments other than a gazillion "do you want to sell it" posts. I have been told it's worth some cash.

Re-capped:


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## Oliver (Jun 25, 2007)

Beautiful ... just beautiful


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## spydertune (Sep 9, 2005)

chad said:


> It's a 299C


Very Nice!

The only 7591 unit I have is a 233. The 222C & 299 (no suffix) I have use EL84's or 7189's. But I've also got some real beasts too: the 272 & 296! They use EL34's & 7581A's! Here's one of a 296. Not mine but it does appear to have KT66's stuffed in it.










OP - Sorry for the thread hijack.


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