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Marantz 2270 with 4 8-ohm speakers

MBuras

MBuras

Restoration is an Addiction
Been a bit absent from the Marantz forum working on some Sony amps. Disgraceful, I know. :D

Have a friend that decided to run 4 8-ohm bookshelf speakers (2 on main, 2 on remote) from his Marantz 2270 and reports the right channel cuts out at anything beyond low volume. Where's the first place I should be looking? Receiver has been recapped by me with a few transistors & relay replaced. Has been working perfectly with 2 speakers for quite a while.

Thanks,
Mike
 
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First of all I would have him check his wiring. Also ask him the exact model of speakers and find out if they are indeed 8 ohm.
Start with the very basic things....does he run it with the loudness on and the bass up. What does he really consider low volume?
If possible go yourself to check out his setup?

I restored a Scott A437 for a friend, he was complaining it would blow speaker fuses at low to mid volume.
Turns out he was using big uninsulated banana plugs and the plug bodies were touching and shorting....

Good luck !
 
Thanks for the ideas. He doesn't live too far away so I'll probably end up stopping over one of these days to check the setup.
 
Just to close this thread out. I visited with my friend to check out his 2270 4-speaker setup. He's running 4 Advent 3002's which according to the manufacturer are rated at 8-ohms. We verified all speakers were wired correctly to the receiver and no wires shorted. Sure enough there's clipping at relatively low volume with all 4 speakers engaged. So I pulled the speakers one by one and measured the ohms across the 2 terminals with my DMM and came up with anywhere between 5.2 ohms to 5.8 ohms. So in my book those are not 8 ohm speakers and probably putting too much load on the receiver when they're all engaged and an active load applied.

I'm going to dig around in the speakers forum to see if there's a reason these speakers are measuring so low compared to spec. I'm not a speaker guy so should be a fun distraction.

EDIT: some quick reads show it's normal to measure a resistance 1/3 lower than nominal impedance so maybe the speakers are fine.
 
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I hope you swapped speakers from each side to see if it was something in one of the speakers. Otherwise it's another trip!
 
rBuckner said:
I hope you swapped speakers from each side to see if it was something in one of the speakers. Otherwise it's another trip!
Click to expand...

You speak wisdom. And of course that's the one thing I didn't do, but here's why. With just the primary 2 speakers engaged volume was acceptable with no clipping. With only the addition of the extra speakers the same speaker that was fine before (one of the primary speakers) was now exhibiting clipping. My logic at the time, possibly faulty, was that the added speaker should exhibit a problem if it added the problem.

Either way I'll probably be back to run a few more checks. It's actually good to catch up and talk stereos/vinyl/etc so I don't mind the short trip. :rockon:
 
I'll assume when run just on the secondary / Remote speakers there was no problem either. Still I'd swap both speakers on the bad side over to the good side and vice versa just to be sure. After that I'd have to guess there's a driver that is low gain in the affected channel somewhere, or is a bit leaky. Possibly an out put? An emitter resistor off value but close enough while using an 8 ohm load? Good luck Mike, you may have a real puzzler.

Quote: "It's actually good to catch up and talk stereos/vinyl/etc..." now it is YOU speaking wisdom! I know I've met some very nice folks in this hobby / side business.
 
I'm no speaker expert, but I have heard that the impedance of some speakers can dip to very low values at certain frequencies.

Tom
 
Weren't there some very early units in the 2270 series that didn't fancy 4 ohm loads? I thought there was an old thread here at AK talking about this issue but I couldn't find it.
 
I had followed some of those discussions as well but even if that is true this one is serial #U462378 so it's definitely a later model. I did not replace drivers or outputs on this restoration as they tested fine during the rebuild. But I don't have a curve tracer so maybe they're breaking down under load. As part of my usual break in process I not only tested this receiver on the bench with 8-ohm dummy loads up to 87wpc before clipping without any strangeness on the scope, but also ran it on my primary system which features two very large Axiom M80 towers which are 4-ohm. No problems detected.

I tend to lean towards the idea of something on the right amp board being weak/leaky/borderline bad. They only received 3 new caps and a new diff pair. Tried to save a friend some money. Figures the one time I don't go whole hog on a rebuild and something goes wrong. Doh!
 
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