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I really need a copy of a Sherwood S-7200 User Manual if anyone could make me a copy.
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I have an S-7200 as well, also sans manual. It is a very (very!) nice little receiver.
I do note that vinylengine has the service manual for the S-7210. I think (??) that the only significant difference between the S-7200 and 7210 is a quad synthesizer (a la Dynaquad, I suspect?)in the latter.
At any rate, depending on what you want to know, you might want to look at the S-7210 SM. It does have specs and a control listing.
Amusingly enough, I used to have an S-7210, too -- but I gave it away...
all the best,
mrh
Thanks!
I actually have a service manual but want the owner manual to figure out what the purpose is for the A/B speaker switch (among other things). The S-7200 is a two channel, 8ohm receiver. I can see playing either speaker pair A or B, one pair at a time, but how would you have to wire 2 sets of 8 ohm speakers so that all 4 speakers would play at the same time?
I know the S-7210 was Dynaquad and when you switched it to play both A/B speakers that used the Dynaquad circuit. But as far as I know, the S-7200 was not a Dynaquad receiver. Am I wrong?
...run the A and B (stereo) pairs in parallel if you would switch it to "A+B". This is pretty standard in the solid state arena (even today); of course, paralleling the speakers means that, e.g., two pairs of 4-ohm speakers in parallel produces a 2-ohm (nominal) load on the amp... and many/most amps wouldn't be too happy for two long driving a load of such low impedance.
all the best,
mrh
That's what I was wondering. What did the owners manual say about a 4ohm load on the amp? If I connect 2 pairs of 8 ohm speakers in parallel and run them using the A/B switch, then I'm putting a 4ohm load on the amp, correct? I didn't think that was a good thing to do to your amp.
It depends on the amp. The results can vary from not a problem to imploding at any level as the amp is totally unstable.
I do not know about the 7200 but their series of receivers that initially did not have a version with a suffix of "A" and later did were unstable into 4 ohms after the the new FTC rating system was mandated. My son uses a S7650CP with a set of 4 ohm speakers for hours at a time and there are no indications of any problems but, he does not run it hard. My earlier S9500c and SEL200 amp and receiver likewise seem okay with the load but, again, I do not run them hard.
An easy way to tell is to run the unit with an 8 ohms load at your usual listening levels and monitor the heat generated by the power transformer and output transistors. The do the same with a 4 ohm load. If the unit runs appreciably hotter with the 4 ohm load then they do not play nicely together. You can sometimes minimize the issue by reducing the volume and seeing if there heat level reduces.
Another test if you do not the test equipment is to get a pair of the original Advent Loudspeaker, the version with the masonite ringed woofer and a pair of The Smaller Advents Loudspeaker. The closer they come to sounding the same the better the amp is as to handling 4 ohm loads. They were designed to sound the same but with most amps do not as most amps are not as stable with 4 ohm loads. Even with the autoformer McIntosh, they do not sound the same. I did hit nirvana with a Rat Shack STA2250, though. The amp section on this receiver is excellent while the tuner sounds terrible. It is easy to mod to use as a power amp and are usually very inexpensive.
Don Brian Levy, J.D.
Toronto ON Canada
Thanks! I went ahead and hooked 'em all up and monitored the heat. There was no appreciable difference that I could tell. I still want a manual though.
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