Sherwood tube use in Vintage Amps

[Ron Glaze]

This a a SHERWOOD Brand question, I find this gear
to be very good vintage equipment, and it plays well
with old JBL. i.e S-5000 & S-5500's

Seems Sherwood makes the same model i-amp using two
types of output tubes either the 7591 & 7868. I can't seem
to get when they did what... at first I thought 7868's
were used early in S-5000II's ,then I see a later version
S-5500II also using 7868's. Did Sherwood have a plan
or was this random, maybe based on tubes available?
I received a Photofact manual which was ment for my
S-5000II model ID. (5013979) using 7591 however the
schematic shows 7868's. eh?
Anyone understand this?
And do people have a preference sonic wise between
either tube?

Regards
rg

 

[ejfud]

Can't help with the questions because it has always baffled me as well.

I do own a 5500 that uses 7868 and it sounds great.

 

[fsjonsey]

I'm guessing they did it by whatever was cheaper at the time of production. Since the 7591 and 7868 are pretty much identical electrically, sherwood probably changed sockets depending on what tube was cheaper during that particular production run.

 

[jaymanaa]

According to the manuals I have, it appears to be a serial number thing. For eaxample, S-5500III S/N 31001 and above use 7868s. S-5500II S/N 38634 and above also use 7868s. I also have a plain jane S5500 here (not mine) with serial number 01723 (obviously an early one) that uses 7591s. Also, it may have a little to do with the circuits, but I prefer the ones with 7868s hands down. To me they have a lot more detail, are faster, and way more dynamic. The 7591 models I've heard (only on my bench) were way to "warm" for my old ears.