Single Revel F208 with low midrange output

[PatentLawyer]

That response from Revel is startling.

 

[617]

Wow, that's really bad support. @amirm doesn't your company sell Revel in some capacity?

 

[dasdoing]

it don't know shit about electronics, but the driver is clearly atenuated by a fixed amount over it's whole range. no low- or high-pass does this. the only thing in this speaker that could do it is one of the 5 resistors, probably the one for the LF adjustment, which actualy shares the binding post with the mid

 

[617]

If they're going to be dicks about it you might just pull the crossover out; I think with these revels it's mounted to the binding post plate.

IDK how a resistor fails. Maybe something shorted it out?

If it's past warranty I bet we could figure it out.

 

[DVDdoug]

It's probably a capacitor. Inductors are very stable (unless they are burned-up). Even without a schematic, you can probably figure-out which capacitors are used in the mid-range and replace them. That's assuming it's not some kind of factory defect... It might have the wrong coil or something. (The odds of the coil having any markings is slim.)

Can you solder? "Worst case" you build new crossovers if you know the crossover frequencies. Parts Express sells bare crossover boards and the components or there are probably other suppliers. It's unlikely that you exactly duplicate the factory design (and frequency response) but at least both sides would match. ...It would be a shame to make an "imperfect" repair like that but it should be better than what you've got now.

Or if you can't do it yourself it's probably worth finding a repair shop even if it's not a Revel authorized shop.

 

[617]

Added shading at the crossover frequencies. Clearly the mid driver crossover at fault.

 

[Thomas_A]

Get the mid crossover out and measure the resistors first. Check soldering. Then caps.

 

[More Dynamics Please]

Considering that the speakers were purchased used and not new I wonder if the previous owner might have known about the issue and was looking to dump the speakers? I'd sure want to express my displeasure to the previous owner though they could easily say there was no issue when they were sold. The Revel warranty says it's not transferable so any repairs would need to be paid for in full by subsequent owners.

 

[MichaelJ]

Thanks for the support, everyone. I purchased this pair used, unfortunately, so I don't know that I have a claim with respect to the factory warrantee. That's the risk with purchasing on the used market, and I've always known that. (Maybe from now on I'll do some cursory measurements to validate speakers are up-to-spec before finalizing purchases...lesson learned???) The sheer size/weight of these makes it extremely inconvenient to ship, but I'm not opposed to driving it to a good shop if it's close-by and they might have a shot at fixing it. I'm in Yardley, PA, which has both a Revel dealer within driving distance and is relatively convenient to Philadelphia and NYC (in case anyone can refer me to a good shop or trusted individual DIYer...) I'm also not opposed to digging into the circuitry myself to try to diagnose the issue, though I don't have a ton of confidence in my requisite knowledge or abilities. I'll keep y'all posted on what I do and find out. And please keep any and all ideas coming...

 

[MichaelJ]

Did another set of measurements just to verify my own sanity on this. I individually measured each speakers' midrange driver from ~1in from the dust-cap. Swapped back the speakers to their original locations in the room and source/amplication channels and ran the same measurements. Pretty conclusive...

 

[617]

Thanks for the support, everyone. I purchased this pair used, unfortunately, so I don't know that I have a claim with respect to the factory warrantee. That's the risk with purchasing on the used market, and I've always known that. (Maybe from now on I'll do some cursory measurements to validate speakers are up-to-spec before finalizing purchases...lesson learned???) The sheer size/weight of these makes it extremely inconvenient to ship, but I'm not opposed to driving it to a good shop if it's close-by and they might have a shot at fixing it. I'm in Yardley, PA, which has both a Revel dealer within driving distance and is relatively convenient to Philadelphia and NYC (in case anyone can refer me to a good shop or trusted individual DIYer...) I'm also not opposed to digging into the circuitry myself to try to diagnose the issue, though I don't have a ton of confidence in my requisite knowledge or abilities. I'll keep y'all posted on what I do and find out. And please keep any and all ideas coming...

Pull the crossovers and at least inspect them. Mark the one that works. Upload pics. We'll figure it out. Revel probably uses crimp connectors for the xover/speaker connection.

Do you know how to use a multimeter?

 

[MichaelJ]

Pull the crossovers and at least inspect them. Mark the one that works. Upload pics. We'll figure it out. Revel probably uses crimp connectors for the xover/speaker connection.

Do you know how to use a multimeter?

I temporarily removed the rear terminal/crossover board of the offending speaker the other day just to take a look. The connections looked good and there was no obvious visual damage. Speaker wire was soldered to the board and it was a little difficult to see all the components. I reinstalled it without taking any pictures, but I'll do it again and take some photos to share here. I have a multimeter and I can take some readings if y'all are willing to provide some basic instructions. I'll report back tomorrow. Thanks again.

 

[Laserjock]

Are we sure the lower output mid is the offending speaker?

The F206 has similar crossover, I wonder if manufacturing installed the wrong component in one of the speakers ?

 

[tmtomh]

Considering that the speakers were purchased used and not new I wonder if the previous owner might have known about the issue and was looking to dump the speakers? I'd sure want to express my displeasure to the previous owner though they could easily say there was no issue when they were sold. The Revel warranty says it's not transferable so any repairs would need to be paid for in full by subsequent owners.

Or the prior owner never measured them and just had a nagging feeling they could be better - never realizing that there was a specific fault/issue like this at play.

 

[FrantzM]

That response from Revel is startling.

+1

 

[Beave]

Remove the midrange driver from each speaker and make sure they're the same model #. Also, if you have a multimeter, measure the DC impedance across the terminals for each midrange driver and make sure they're just about the same.

If they are, then it's likely a crossover problem.

****(Edit to add: I just read the thread more closely, and I saw that you already swapped the midrange drivers between the two speakers. Since the problem followed the speaker, not the midrange driver, it must be that the drivers are ok and it's the crossover somewhere.)****

I think the F208 crossover is actually three separate boards, one for the two woofers, one for the midrange, and one for the tweeter.

You'll probably have to remove drivers to get to the midrange crossover. My guess is that it's right behind the midrange driver, so hopefully you can see it when you remove the midranges.

Here is a pic of the three crossover boards for the little brother speaker, the F206:

The top board is the tweeter crossover. The middle, for the midrange, and the bottom board for the two woofers. The F208 crossovers should be similar, except that the board for the woofers will be more complex due to the addition of the boundary gain switching circuitry.

 

[Beave]

I found this review from 6Moons (6Loons) that shows a couple of the boards for the F208 crossover:

https://6moons.com/audioreviews/revel2/2.html

The board directly connected to the binding posts on the rear is just a resistor bank for levels for the two switches.

Then I think there are three separate boards, as with the F206 in my previous post, one for the woofers, one for the mid, and one for the tweeter.


And here is a 6moons review of the F206, showing the midrange removed and the midrange crossover behind it:

https://6moons.com/audioreviews/revel2/2.html

 

[617]

I suspect it isn't the mid crossover but rather that other board where the trims are.

 

[Larry B. Larabee]

You can compare the component values against the other speaker to see if there is any difference.
About Revel's response, It's a Samsung company and I suggest that everyone get used to it from now on.

 

[Beave]

I suspect it isn't the mid crossover but rather that other board where the trims are.

That's a good guess - with all those resistors. But looking closely at that board, all I see is outputs to the woofers and to the tweeters (HF and LF ins and outs). I don't see anything going to the midrange driver.