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Marantz amp problem, sudden "gargly" sound


Larry Kart

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1 hour ago, Larry Kart said:

Took the speakers in to Audio Consultants, and they/we heard the same thing I've been hearing at home. They found what we were hearing to be "strange" but will have their tech take a look and report back. So it's almost certainly/exclusively the speakers that are the problem. Also, almost without doubt, if there is a way to fix/repair the problem, that would be worthwhile. A new pair of B&W 805s now goes for $7,000!

Fuck that! 

Glad they're on the case, Larry. 

Still incredibly strange. 

1 hour ago, sidewinder said:

 

Sounds about right. Scary !  I would love to try a set of the new Dynaudios but the 'damage' would be comparable.

Which model? 

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1 hour ago, Larry Kart said:

Took the speakers in to Audio Consultants, and they/we heard the same thing I've been hearing at home. They found what we were hearing to be "strange" but will have their tech take a look and report back. So it's almost certainly/exclusively the speakers that are the problem. Also, almost without doubt, if there is a way to fix/repair the problem, that would be worthwhile. A new pair of B&W 805s now goes for $7,000!

When B&W switched over their entire Nautilus line to diamond tweeters in 2010, the list prices were nearly tripled. As a result, the used market for the older Nautilus speakers without the diamond tweeter has spiked recently.

If yours need work, I would definitely get it done. They are nice sounding speakers.

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2 hours ago, Kevin Bresnahan said:

When B&W switched over their entire Nautilus line to diamond tweeters in 2010, the list prices were nearly tripled. As a result, the used market for the older Nautilus speakers without the diamond tweeter has spiked recently.

If yours need work, I would definitely get it done. They are nice sounding speakers.

I like them better than any speakers of just about any size I've ever auditioned. To me they just sound like "music."

BTW, while I was waiting in Music Direct's listening room for them to check out my amp yesterday, I was listening to, I think, some George Benson played though Wharfedale Diamond 250 Tower Loudspeakers, around $2,600 a pair. Just awful IMO, trashy and brittle.

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Oooooo... I'd like to hear those! Still absolutely LOVE my Excites. Dynaudio knows their stuff. 

Have you seen some of their really high end models? If they sound even a quarter as good as they look, they must be phenomenal. They have some serious cabinet designers in their studio. 

Edited by Scott Dolan
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5 hours ago, Scott Dolan said:

The problem being the only way to blow a tweeter is by overloading the voice coil, which would have to be done by cranking the tone control/EQ to limits it cannot handle. Is there any other way? Because Larry stated earlier he's only used factory settings. 

A mono Miles album with the treble turned up could have been the culprit. His piercing trumpet, with or without harmon mute, used to regularly cause my B&W's to shut down when I employed an EQ in the chain. 

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2 hours ago, Scott Dolan said:

You mean it made your amp shut down? 

No, the speakers. They were late 80's B&W's (CM 1 CM2 - https://www.google.com/search?q=b%26w+cm1+cm2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwicpLW3t7LWAhWHKiYKHZwGAhkQ_AUICygC&biw=1018&bih=550). The Miles Tokyo disc with Sam Rivers would shut them down every time because I was using a mild smiley face EQ . I presume it was a built-in protective mechanism which Larry's speakers apparently didn't possess. And, again, it was only Miles. Diz, Don Cherry, Roy, etc., never had the same effect. Nor for that matter did Terry Gibbs.

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1 hour ago, Scott Dolan said:

Interesting. I've never heard of any speaker that had an emergency shutdown mechanism built into it. 

How did you reset them?

No "reset" was required. I just got in the habit of listening to Miles without EQ and as I upgraded my gear, slowly weaned myself from using it in general. I'm computer/file based now and the only time I use EQ (or DSP) is when listening to boots. And even then I'm careful to make sure the output gain is reduced to compensate for any EQ I apply that might cause clipping.  

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13 hours ago, Scott Dolan said:

Interesting. I've never heard of any speaker that had an emergency shutdown mechanism built into it. 

 

I'm still using the same POS-ish pair of Fisher ST-915s that my wife had when I met her back in 1981, and they do each have a reset button on them. I have triggered it on occasion, Sex Pistols, electric Miles, and Ellington's Great Paris Concert.come to mind as culprits. There is such a thing as "too loud" after all, at least for these speakers (which we bought by her at a furniture store as part of a Sanyo-Fisher component system when she was divorcing her first husband. The speakers have survived longer than did their relationship, although in terms of quality...).

These are not them,but they have the same feature mentioned here:

abbf277547544a2abd68b19238861c31.jpg

 

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B&W speakers back then had a protection circuit built into them. Here's the owner's manual for the CM-1/CM-2 Matrix speakers that dicky is talking about: http://bwgroupsupport.com/downloads/manuals/bw/CM1-CM2-OM.pdf On Page 5, they mention the APOC circuit.

Edited by Kevin Bresnahan
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2 hours ago, Scott Dolan said:

I wonder why it didn't become commonplace. 

Too expensive to justify, perhaps? 

It's very hard to put current protection in a signal path that doesn't change the signal going through it. The B&W APOC circuit had several diodes that shunt excess current to ground until they shut off the speaker completely. As these circuit elements started to turn on, they most likely changed the sound. There are forums around the 'net telling people how to bypass or remove the APOC circuitry in these older B&W speakers and the dramatic improvement in sound after it's done.

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So there's no way to build a flat cutoff rather than speed bumps? Almost seems counter-intuitive, IMO. If you're going to create hurdles that alter the signal, why not just shut the whole thing down at the first sign of trouble? 

I don't think anyone would prefer an altered audio signal to no signal at all. 

Am I missing something? (no pun intended, BTW) 

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1 hour ago, Scott Dolan said:

So there's no way to build a flat cutoff rather than speed bumps? Almost seems counter-intuitive, IMO. If you're going to create hurdles that alter the signal, why not just shut the whole thing down at the first sign of trouble? 

I don't think anyone would prefer an altered audio signal to no signal at all. 

Am I missing something? (no pun intended, BTW) 

 

What you're asking for is a fuse. And sure, some speakers are fused. But of course, even fuses have their limitations due to the dynamic nature of audio signals. Remember, most tweeters blow because the tweeter draws more current than the thin voice coil wires can handle. So if you fuse the speaker at a current level that protects those thin tweeter wires, that current limit will probably be too low for the woofer to reproduce a loud passage filled with low bass. The best fused speakers have separate fuses for each speaker element. Then there's the resistive nature of the fuse. It's not a simple wire. It has resistive properties that many claim hurts the sound.

Protecting speakers is not as easy as it sounds (pun intended).

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Update:

Amp checked out by tech at store, driving other speakers, everything sounds fine (heard the results myself).

Speakers checked out by tech at store (different store, both high-end places), everything sounds fine (heard the results myself).

Speakers hooked up at home, same gargly problem.

Also, using new Rocket 33 speaker cables.

Tried hooking up everything to a different wall outlet, no change.

Unhooked my power-line conditioner, no change.

Sound through headphones is still as it should be.

I'm baffled, as is everyone else out there who's tried to help.

Audio Consultants suggests that their tech, for a price, could come out to the house, listen, and perhaps detect something that everyone has missed, or they could lend me an amp and see if that makes a difference. I'm thinking of an exorcism.

 

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