What to do with unsaleable speakers?

[Mike Rubin]

Recently, my system developed a severe channel imbalance, with the left speaker being louder than the right.  I have been troubleshooting to find the source of the imbalance by swapping cables and sources.  After switching the speaker cables at my amp, I concluded that the issue almost certainly is with my 15 year-old Revel F32 Concerta speakers because the imbalance did not change.  

 

Reading a bit online, I concluded that the problem likely is with the crossovers or with one of the drivers.  It might be my hearing to blame, although there aren't huge differences between ears that would explain the shift in imaging.  My recent hearing exam discloses that I no longer hear anything in either ear above 10khz, so I can't really hear tweeter-only information with my ears near the tweeters, but I ended up suspecting a tweeter failure.  After coming to that conclusion, I called Revel, which confirmed that, in the F32 model, it's likely to be the tweeter that failed. 

 

Unfortunately, Revel no longer stocks parts for speakers this old and it doesn't have a factory-authorized service facility within 400 miles of here.  If parts were available and affordable, I might drag these 75 pound things down the stairs and into the van so I could take them to an independent facility to have them evaluated and repaired, but that can't happen without parts to fix them.

 

I now am reluctant to try selling these things because I can't guarantee they work properly.  I think I have the original boxes buried somewhere at the back of a storage unit.  Shipping two 85 pound boxes runs about $250 each way, so I can't see sending them anywhere from which they might have to be returned.  I could list them "as is" on Craigslist for a few hundred bucks, I suppose - they would be worth at least $1000 if healthy - but my wife is reluctant to admit Craigslist purchasers to our premises after being voir dired for a jury trying a murder that occurred during a Craigslist electronics sale.  I guess that leaves Goodwill, which could either sell them at retail or to an electronics recycler.   

 

Any other venues for disposal that I am overlooking?

 

I am not looking forward to replacing these, especially with compromised hearing.

[Mike Rubin]

2 hours ago, GregWormald said:

I would have though that there was a local expert/enthusiast who could do the evaluation and find a way to repair such a speaker. Admittedly it could be hard to find a useful tweeter, but it's also possible that a standard crossover component (or something else easily obtainable) could be causing the problem.

 

Even if it's the tweeter, with your high-end hearing loss, close might be good enough--providing that you still like the sound.

I have zero doubt that sort of expertise exists, but I don't know how to find it, unfortunately.

 

You are right about the hearing loss. The speakers still sound listenable.  The concern at this point is about the effects on the imaging.  Maybe I should just spend some time rearranging placement so that the balance issues are minimized.

[Mike Rubin]

1 minute ago, Lone Mountain Audio said:

 

Boy I understand that!  I have a n old pair of Dahlquist DQM 909 with Magnat drivers.  One speaker has a  mid not working right, and needs to be replaced.  Where on earth would one go to find these drivers that no longer exist, with a manufacturer that no longer exists?  

 

Working in the industry, drivers go obsolete all the time.  I know some folks who own older ProAc Studio 100s and the woofers are no longer available.  There is no solution.  You want to know that person out there who is sitting on a few spare parts, that must exist, but how would you find them?

 

Brad

There might be some Revel parts at one of its distributors, I found out, although I am not holding my breath.

I have been mitigating the issue.  I switched the two speakers and the louder left is now the right.  (I can’t lift the speakers, but I was able to get a blanket under them and drag them along the hardwood floor.)  The louder speaker now plays in a less-enclosed space and the softer one is being reinforced by the proximity of an armoire where I keep the electronics.  The channels now are almost balanced, actually, so that much is good for the moment.

 

At some point, I will have to get serious about repairing or disposing of these speakers.  Until then, this change will help me limp along. 

[Mike Rubin]

3 minutes ago, GregWormald said:

I'd be trying internet searches (Google, DuckDuckGo...), asking questions at hi-fi forums, consulting local dealers/repairers, any FAQs for Revel, etc. Good luck.

Thanks!  Good tips.

[Mike Rubin]

1 hour ago, rwwjr44 said:

You may be able to find tweeters that are a good match for what you have and change them out. There are probably lots of substitutions that will work well. Ditto the crossovers. Look at the later Revel models for which parts are still available.

 

Thank you. 

 

During my conversation with the Revel tech support guy, I got the impression that this isn't a great idea, but maybe he just wanted me to buy new speakers. 

 

If I did this, I assume I would need to buy two of these, so that the two speakers are configured identically? 

[Mike Rubin]

59 minutes ago, Blake said:

HARMAN LUX-A USA Return_Repair Form REV 10.11.16.pdf 495.15 kB · 1 download

 

Hi Mike, 

 

When my Revel subwoofer went out, I was able to just remove the rear panel and then I mailed the panel to Pyramid Audio (Revel authorized service provider).   They fixed it and mailed it back to me at very reasonable price.  Could you just remove the tweeter and mail it for service?

 

P.S. I understand the Performa F32, C32, and M22 speakers share the same tweeter.

Nope!  The Revel support guy checked and said there are no repair parts available.  He told me that they stop carrying repair inventory after about 15 years from start of production (although I suspect that it's really the industry-standard seven years from end of production, given the dates of start, end, and inventory discontinuance that he gave me.)

 

At this point, I think I will live with what I have until I replace these. With at least 20 years of speaker development since these came to market, I probably can find their equal at less than what I paid for these. 

[Mike Rubin]

14 minutes ago, bluesman said:

I don’t think you know exactly what’s wrong yet - you’re trying to treat an unknown disease on the basis of guesswork, but you need facts to make the diagnosis. The fact that tweeters “often fail” in that model does not mean that yours did.  You describe the imbalance as “severe” but say you can’t hear anything over 10k.  Your tweeters start putting out at close to 3k, as I recall, and that’s where timbre, brilliance, “air” etc start to be defined but none of the fundamentals and major harmonics are that high.

 

It’s a bit hard to believe that you can easily hear a gross imbalance in SPL from lack of output above 3k, especially if you truly have no functional hearing sensitivity above 10k. It’s a truly rare audiogram that breaks sharply at a specific frequency and even rarer if it’s bilaterally symmetric - so you almost certainly have a progressive loss of threshold sensitivity that starts at or below 1k.

All you know for sure (assuming that it’s constantly on the same side despite swapping input or output channels/cables) is that there’s a problem in one of your speakers.  There are several things you can do to get a more accurate diagnosis.

 

1. A simple, cheap SPL meter is very useful, but if the imbalance is truly big, just download a free SPL “meter” for your smartphone 
2. You can use recorded music as a test source, but you might want to use an online sine wave generator to ensure consistency of input levels and signal between channels. You can use the audio out jack on your phone or computer - SQ is irrelevant here.  Obviously an external DAC is also fine to use.
3. I’m pretty sure your speakers are designed for biamping.  Remove the jumpers and connect your amplifier’s outputs to the bass input terminals ONLY.  Listen to and measure the SPL from each channel from a close, fixed distance on the axis of each driven speaker.
4. Move your speaker leads to the high frequency terminals and do it all again.  If using a tone generator, start at 1k and go up from there.

I don’t know where those terminals are in the crossover chain, i.e. whether there’s any filtration between them and the drivers or if they’re direct (which I doubt). You’ll need to find out from Revel, because it will affect the information this test will give you.  If those terminals are inputs to the crossover, any imbalance could still be caused by a driver or a component in the crossover.

If the imbalance is audible only through the bass terminals, the problem is almost certainly not your tweeter.  If it becomes audible at some point while sweeping the frequency upward using a tone generator into the full frequency inputs (with jumpers in place), you’ll know where it starts and that should narrow the search.  Just for completeness, you might also want to check the jumpers themselves and the terminals to which they connect.

 

And if it really is a tweeter, you can simply remove the jumpers and wire up to a pair of external add-on tweeters. There used to be many on the market.  You could even use a good, small, inexpensive “monitor” as your new tweeter - the JBL 305s are excellent and have onboard adjustable attenuation.  If your HF hearing is that compromised, this should be fine - just sit them on top of the Revels.

 

Good luck!

Thank you very much for this detailed precis!  
 

I will be home a lot for the next few months - nearly all of us will- and this gives me a chance to undertake more detailed testing.

 

Just a few things:  

 

These are jumpered now, so I can play with the two sets of terminals that you suggest.  
 

I also have a system test record that plays tones at about 40 closely-spaced frequencies.  I haven’t had the patience to start at the bottom, but, beginning at about 2500 hz does reflect an audible imbalance, although the degree depends on the end of the couch that I occupy.  I will use my phone’s SPL app to verify more precisely; that hadn’t occurred to me.

 

Finally, if I end up having to mate outboard tweeters, I will just move on from these speakers.  Their market value isn’t really that high snd I’ve gotten my money’s worth ovr the more than 15 years I have had these.

 

Thanks again!