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4 speakers on my Sansui 7000?

Sonofswede13

Sonofswede13

Active Member
Hello!

I am pretty much a noob here, but have had the vintage hear bug for a couple years and have posted the occasional question to you fine folks and received some excellent advice.

I was wondering if anyone knows if it's safe to run 2 sets of 8 ohm speakers on my Sansui 7000. I just picked it up off of CL today and grabbed some Dynaco a25's at the same time. I brought it home and plugged it in with my HPM 100s to compare/contrast the speakers and found I am most in love with this when I run all 4. Admittedly, this could just be the novelty of it, but so far, I love the sound.

I have one set in Speaker A and one set in Speaker B. I assume this means I'm running a 4 ohm load, but I don't understand the technical aspects of "Why a 4 ohm load stresses your amplifier" really at all.

I listen often late at night at lower volumes, but I do like to crank it now and then.

Does anyone know if it's safe to run a 4 ohm load on this beautiful old receiver (if that's what I'm doing?)

Thanks folks. As always, your time, knowledge and assistance is greatly appreciated.

Best,

-john

p.s. I plan to try the same thing with my 9090 when I can afford to have it fixed, so if you happen to know the answer to the same question with that receiver, I'd be much obliged!
 
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Of course, I figure that if they have a switch that says "A+B" and "A+C" that it should be fine, but I don't know what they were thinking in terms of ohms and the info I see about 4ohm loads being hard on amps worries me. Thanks!
 
It appears to be OK to do this, (see spec) however I would be cautious about cranking it too much.


7000_4.JPG
 
Awesome, thanks! I saw this spec sheet online, but couldn't make it out. It seems I should keep a close eye on the temp. I'll make sure to do that at any higher volumes. After several hours at a low volume, she was giving almost no heat at all.

Thanks much for your help!

-john
 
SOA (safe operating area) is a strange thing. The danger spot is at far less than half power.

That said, a 7000 should take it just fine. I've never seen one with bad outputs.
 
I have heard the 7000 has no speaker protection and could feed DC straight to the speakers. In the event that there is a failed cap or transistor the power limiter would reduce the risk of frying your speakers.
 
What size speaker cable are you using? I have read on other sites that some are using outdoor landscaping cable 14 gage to keep temps down, I have a set of bozaks that are power hogs on my 5000X that was running warm to hot so I think that the 14 gage will work for me and it does fit into the connector in the back of the Amp. Ken
 
Thanks again!

59volvo said:
I have heard the 7000 has no speaker protection and could feed DC straight to the speakers. In the event that there is a failed cap or transistor the power limiter would reduce the risk of frying your speakers.
Click to expand...

I'm unfortunately, not sure what this means. I guess I don't know what a power limiter is? Is it something I need to get to protect my speakers or is it something built into the receiver that you're saying should help protect them in this event? Sorry! I don't know jack about the insides of these yet. I bought a Sansui 350 that's a little beat up. I'm planning on using that to try and learn a little.
 
sansui 74 said:
What size speaker cable are you using? I have read on other sites that some are using outdoor landscaping cable 14 gage to keep temps down, I have a set of bozaks that are power hogs on my 5000X that was running warm to hot so I think that the 14 gage will work for me and it does fit into the connector in the back of the Amp. Ken
Click to expand...

It's pretty much as big as I can get in the connectors! The HPMs are hooked up with Signature Select 14. The Dynacos I'm not sure, but it's some pretty hefty "Monster Compact Precision Stranded High Resolution Speaker Cable with Magnetic Flux Tube and LPE Dialectric." Which, btw, seems like a pretty ridiculous name.

But your question does bring me to this: Should I be using the same size/type and length of speaker cable out of both sets of speaker outs or does that only matter for L/R of the amp?

Thanks!
 
I think that the length is not so much of a concern it's the length of the run out to the speakers over 30-40' is when you need the bigger gage because of resistance in the smaller gage wire, efficent speakers play a role as well,the bozak's I am useing are only 15-20' away from the 5000X I had been useing 16-18 gage so think about all the factors.good luck Ken
 
Up to 50' 18 or 16ga. Over 50', 14ga. That's info I got from FISHER and PIONEER Way back when most of my equipment was new (Early 70's.)



Larry
 
Thanks all for the advice and Hyperion for the clear look at that spec sheet. She seems to be handling this just fine! And I'm loving it. Appreciate the help.

-john
 
59volvo said:
I have heard the 7000 has no speaker protection and could feed DC straight to the speakers. In the event that there is a failed cap or transistor the power limiter would reduce the risk of frying your speakers.
Click to expand...

This is not true because the 7000 is capacitor coupled. It cannot feed dc to your speakers.

Also, even though the 7000 has a built in "Power Limiter" switch on the back (which it isn't really), it could still output enough power to blow speakers. The power limiter just selects between two different power supply rail voltages, (62 or 45) the full 70 watts and about 45.

The 7000 has a Protector board F-1317, but all it appears to do is ground the input to the drivers if too much output is measured at it's inputs. You have to power off and back on to reset it. So if it loses sound, power cycle it.

I have found the SCR shorted on this "protection" board, and that was the only thing wrong with the rcvr! I disable it on all the 7000s I work on for that reason. Just cut the blue and grey wires that feed it from the outputs.
 
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