FA: Sherwood s 8000 Tube Receiver - Awesome Condition
OldGold
The original Sherwood 8000 is one of the prize gems of the tube
audiophile classic era. It is widely recognized as one of the top
vintage USA receivers ever made.
This unit was just removed form it's one and only home inside a custom
built-in home system of a retired audiophile. It has been meticulously
cared for and today it looks and sounds AMAZING. Original early 1960.
The face is near flawless. No wear to any of the white finish or
lettering. Looks MINT!!
Unit has been tested to power up and provide all basic functions.
Amazing!!
Unit has mostly all original Sherwood tubes preamp section, EV tubes
in the power section. 7868 Tubes in the Power stage
Please view all the photos. I'm happy to send HI RES photos on
request.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260656369665
Patrick Turner
That is an impressive tubed stereo receiver. If it is a 1960 model
then does it not predate the addoption of the Zenith-GE multiplexing
for stereo info using a 38kHz sub-carrier?
I searched for a free online available schematic for the S-8000 which
this receiever seems to be. Probably it is after 1961 and with the
addopted standard MPX stereo decoding circuits of the time. Anyone
bidding for this would be able to check this out because you have a
picture of the front cover of the owner manual.
I could not find a free schematic although someone was able to sell a
service manual for just about all Sherwoods from those ancient times.
These old sets usually develop a number of faults over the years. It
happens also with Scotts and Fishers et all. But they do respond to
having all dud tubes and R&C parts replaced along with some upgrade to
electrolytic cap values, and some possible revisions to output tube
biasing methods.
A schematic is essential for upgrade work unless the upgrader can take
the time to trace the whole schematic and draw it up accurately and
then make intelligent mods to improve performance.
Patrick Turner.
Watt? Me worry?
>
> - Show quoted text -
Hi RATs!
Early 1960's, perhaps? Not many iBuyers are able to discern the fine
line betweet 48 and 50 years ago...
My first "steerio", in 1971, was a Sherwood. I carefully compared all
the measurements in the Stereo Review Buyer's Guide and bought the
best numbers, but, in those days, I thought the major and minor
horizontal diameters of women were important, too. Numbers are
perfect, right?
But, it was SS, and built in Japan.
Doing manufacturing where labor is cheaper is not exactly wonderful
news... unless you live in the neighborhood where the jobs arrive.
The only thriving business in the USA these days is bullshit. Rush
Limbaugh is the savior of mankind, ask him ;)
Well, perhaps not, but, he does tell cutesy lies that entertain his
"ditto-heads".
Even though they are listening on the radio in the car they now live
in.
Theere are many games available on Earth. The most popular is trying
to become really rich so you do not have to starve like the people you
screwed to get there. Your grandchildren will never even think about
it. But, they won't think about you, neither.
Happy Ears!
Al
MarkS
"Patrick Turner" <in...@turneraudio.com.au> wrote in message
news:68f4631a-fb50-45e1...@t5g2000prd.googlegroups.com...
Patrick Turner.
I have one of these. It's a pretty stable & solid performer. It might not
have the FM high fequency extension of my Scott 340B but its well built and
neat looking. It currently resides on my work bench riser with a pair of
Infinity speakers.
There were at least 4 circuit variations I'm aware of. The last version was
about 1964 I think.
Cheers,
Mark
John Byrns
<68f4631a-fb50-45e1...@t5g2000prd.googlegroups.com>,
Patrick Turner <in...@turneraudio.com.au> wrote:
> That is an impressive tubed stereo receiver. If it is a 1960 model
> then does it not predate the addoption of the Zenith-GE multiplexing
> for stereo info using a 38kHz sub-carrier?
> I searched for a free online available schematic for the S-8000 which
> this receiever seems to be. Probably it is after 1961 and with the
> addopted standard MPX stereo decoding circuits of the time. Anyone
> bidding for this would be able to check this out because you have a
> picture of the front cover of the owner manual.
> I could not find a free schematic although someone was able to sell a
> service manual for just about all Sherwoods from those ancient times.
The top of chassis view clearly shows the presence of a post June 1961
Pilot Tone Stereo decoder.
> These old sets usually develop a number of faults over the years. It
> happens also with Scotts and Fishers et all. But they do respond to
> having all dud tubes and R&C parts replaced along with some upgrade to
> electrolytic cap values, and some possible revisions to output tube
> biasing methods.
What revisions do you recommend to the output tube biasing methods?
Most of these old receivers originally used a "fixed bias" scheme.
--
Regards,
John Byrns
Surf my web pages at, http://fmamradios.com/
Patrick Turner
> In article
> <68f4631a-fb50-45e1-8d23-d6ed908a7...@t5g2000prd.googlegroups.com>,
> Patrick Turner <i...@turneraudio.com.au> wrote:
>
> > That is an impressive tubed stereo receiver. If it is a 1960 model
> > then does it not predate the addoption of the Zenith-GE multiplexing
> > for stereo info using a 38kHz sub-carrier?
> > I searched for a free online available schematic for the S-8000 which
> > this receiever seems to be. Probably it is after 1961 and with the
> > addopted standard MPX stereo decoding circuits of the time. Anyone
> > bidding for this would be able to check this out because you have a
> > picture of the front cover of the owner manual.
> > I could not find a free schematic although someone was able to sell a
> > service manual for just about all Sherwoods from those ancient times.
>
> The top of chassis view clearly shows the presence of a post June 1961
> Pilot Tone Stereo decoder.
>
> > These old sets usually develop a number of faults over the years. It
> > happens also with Scotts and Fishers et all. But they do respond to
> > having all dud tubes and R&C parts replaced along with some upgrade to
> > electrolytic cap values, and some possible revisions to output tube
> > biasing methods.
>
> What revisions do you recommend to the output tube biasing methods?
> Most of these old receivers originally used a "fixed bias" scheme.
I cannot see the full schematic of the receiver in question.
But many such things were seriously compromised by very poor bean
counter inspired biasing of OP tubes.
It was common practice to use the heater filaments of the phono
stages for the common cathode resistance for all 4 output tubes so
that you could have Ek at every OP tube at +25V at a total Ia = 300mA,
if there were 4 x 12AX7. Trouble occurs when OP tubes drift and don't
all bias the same with Ia variations of +/- 70% as I have seen in bad
cases.
Almost none of the well known brands used separate individual RC
cathode biasing for each OP tube which was the most user friendly
method. None I know of ever had separate trim-pots to set the fixed
bias which most owners got wrong causing smoke and burned out parts.
As I have so often said, much of the design methods used in 1960
receivers was bloody crook shite, and they always used a minimum cost
design method which meant poor lowest common denominator performance.
Patrick Turner.
MarkS
Patrick Turner.
One integrated amp, the Fisher KX 200, had a nice arrangement for setting
the fixed bias. A bias and balance pot for each pair of output tubes. It
also had a little meter and a rotary switch so that each pair could be
biased and balanced fairly easily. The KX 200 was a kit, the kit instruction
manual has some tough in cheek humor to it which is a little entertaining.
Pretty cool. My LK72B Scott also has the bias and balance pots but no meter.
Probably the exceptions rather than the rule I would imagine.
MarkS
Patrick Turner
> "Patrick Turner" <i...@turneraudio.com.au> wrote in message
>
> One integrated amp, the Fisher KX 200, had a nice arrangement for setting
> the fixed bias. A bias and balance pot for each pair of output tubes. It
> also had a little meter and a rotary switch so that each pair could be
> biased and balanced fairly easily. The KX 200 was a kit, the kit instruction
> manual has some tough in cheek humor to it which is a little entertaining.
> Pretty cool. My LK72B Scott also has the bias and balance pots but no meter.
> Probably the exceptions rather than the rule I would imagine.
>
>
> - Show quoted text -
In Australia we didn't get FM transmissions until the 1970s and so
there were never any big sales of FM receivers with tubes in them. By
the time FM arrived here the sets were all imported and already they
were using integrated chipery.
Meters and bias balance and bias pots are nice, but deadly in the
hands of technically challenged inexperienced brain free audiophiles
who still manage to wreck good tube gear. They find a way, somehow.
Nobody who has ever manufactured new audio gear or kits with tubes
has provided fail safe bias protection which visually indicates bias
balance status at all times ( with a pair of LED ) AND with the added
circuit which turns off the amp if one or more OP tubes conducts more
than twice the idle dc current for longer than 4 seconds.
Patrick Turner.
JC
The older S8000's used 12AX7 tubes in the low level stages, and the newer
ones use the 6EU7. The schematics are somewhat different.
I have the older model, bought from a HI-FI store in Austin, Texas back in
1977 for $15.00 as-is not working. Since then I have gone through it twice,
although some of the original tubes remain. I put in a new set of Sylvania
7868's in 1981, and they remain there to this day. The Sherwood logs about
10 hours a week minimum use since it is connected to the home entertainment
system whick includes the Nintendo Wii where we stream Netflix almost daily.
Back in 2002 it finally crapped out after limping for a while. All the
wiring to the power transformer started falling off. I almost junked it.
http://pages.prodigy.net/jcandela/Sherwood_S8000/Transformer/
After redoing that wiring, along with the output transformers as well
(primary only), I got a wild hair to re-cap, and then start a crazy crusade
to play with SS FET regulators:
http://pages.prodigy.net/jcandela/Sherwood_S8000/HV_REG/S8000_Mods2.htm
All those regulators fit on a 2" x 2" perf board with a small processor
heatsink with a tiny fan. Been working fine for the last 7 years, other than
losing a receiver IF tube filament. The sound is awsome with really enhanced
bass due to the stiffer plate and screen supplies to the output tubes.
I don't necessarily reccomend anyone do these mods unless you have a well
equipped bench, and a lot of understanding of how things work. It is tough
to make solid state requlators short circuit proof. I tried, but was too
chicken to test! :-)
Jim in Texas