Single Revel F208 with low midrange output

[MichaelJ]

First of all, "Hi." I'm a longtime lurker on the forum. I have a pair of Revel F208s, one of which seems to be outputting 5-10 fewer db in the midrange than its counterpart. I purchased this pair used a few months ago, and, up until now had assumed that the disparity I was seeing in my room measurements was due to room anomalies and not the speaker itself. It was not as obvious as you'd think during critical listening and Dirac on my SHD did a pretty good job of correcting for it. Nevertheless, something has always felt slightly "sub-optimal" about this setup, and it's been nagging at me for so long that I've decided I can't ignore it any longer.

Lo and behold, it's definitely the speaker. I've taken some measurements from my listening position of both speakers in the exact same location in the room. The difference in the midrange is pretty obvious, proving it's not the room or my associated equipment causing this. Seems to me it's either an issue with the midrange driver or the crossover network. Is there any way to determine which one based on the measurements I'm sharing? Could it possibly be caused by faulty or out-of-phase wiring in the offending speaker? Thanks in advance.

 

[Laserjock]

Using the same channel power and preamp on both?
Maybe reverse wiring On speaker ?
Check the level dials on the speakers for boundary and tweeter ?

 

[MichaelJ]

Yes, the measurements above are using the same volume level, same preamp/power amp channel, wiring, etc. Only difference is I swapped physical speaker. Both speakers are set to normal on the boundary knob and “0” on the tweeter level adjustment. In the measurements I’ve shared, you’ll notice that the bass and treble lines match almost exactly—it’s only in the 250hz-2.2khz where it diverges—which indicates to me that the issue is isolated to that frequency range and most likely due to the midrange driver, the crossover network, or, maybe, the wiring thereof.

 

[dasdoing]

there is no phase issue. the mid-driver is just quieter for some reason. First thing to do is contact Revel support. Might be known issue to them

 

[Laserjock]

Very odd indeed.
Only other option for you to try is to physically swap the midrange driver on both units to see if it follows.

Might be inclined just to see if you could purchase another midrange and swap it.

 

[MichaelJ]

Very odd indeed.
Only other option for you to try is to physically swap the midrange driver on both units to see if it follows.

Might be inclined just to see if you could purchase another midrange and swap it.

Good idea—just tried this. Swapping the midrange driver did NOT change the output of the speaker. I guess that proves the driver is up-to-spec. I guess that leaves the crossover network as the problem? I reached out to Revel support, so I'll wait to hear what they have to say on the matter.

 

[Laserjock]

Good idea—just tried this. Swapping the midrange driver did NOT change the output of the speaker. I guess that proves the driver is up-to-spec. I guess that leaves the crossover network as the problem? I reached out to Revel support, so I'll wait to hear what they have to say on the matter.

I would say you’ve done what you can short of checking/swapping crossovers

 

[Thomas_A]

Crossover fault.

 

[FrantzM]

Contact Revel support.

 

[617]

The driver is clearly playing, just quieter than it should. Very odd. Unlikely to be a driver problem; I feel like driver variation crops in in differences in the fundamental resonance of the driver, not differences in over all output.

 

[Laserjock]

The driver is clearly playing, just quieter than it should. Very odd. Unlikely to be a driver problem; I feel like driver variation crops in in differences in the fundamental resonance of the driver, not differences in over all output.

Yes, he figured that out already by swapping individual drivers.
Would think a bad component or crossover difference would have a different response and not just a lower output of same response.

 

[dasdoing]

how does a crossover atenuate a whole driver? that doesn't seam to be the cause.
it must have something to do with the active resistors, though they strangely should be only wired to LF and tweeter. maybe a short made mids pass through one of those resistors?

 

[Thomas_A]

Baffel diffraction compensation components. Most likely for the mid.

 

[MichaelJ]

At least part of the crossover network is attached to reverse side of the binding posts, so I briefly removed it to see if anything looked askew or damaged. To my untrained eye, all the connections seemed pretty solid and the components looked intact.

I will need to double-check this, but I'm pretty sure the midrange driver has its own sealed compartment in the enclosure with a decent amount of polyfill (or similar material). Would more or less of that in the offending speaker affect the driver's SPL?

 

[Thomas_A]

Does anyone have the schematics?

 

[JayGilb]

Looks like there is a attenuator pad on the tweeter and a normal/boundary switch on the woofer.
That adds additional wiring complexity and it might have been incorrectly wired at the factory.

 

[617]

Baffel diffraction compensation components. Most likely.

Although crossovers don't have components dedicated to correcting individual acoustic phenomena, the midrange likely has some kind of over-all padding included to bring it down to the level of the woofers. Generally you want this to be kept to a minimum as these resistors will often be the hottest running components in the whole crossover.

 

[Thomas_A]

Although crossovers don't have components dedicated to correcting individual acoustic phenomena, the midrange likely has some kind of over-all padding included to bring it down to the level of the woofers. Generally you want this to be kept to a minimum as these resistors will often be the hottest running components in the whole crossover.

Agree with that. Schematics would help.

 

[MichaelJ]

Revel support was no help. Had a couple emails back-and-forth, culminating in this:

It is highly unlikely and exceedingly rare that it would be your crossover network. But here is the problem, in order for you and us to really know that, you'd need a dealer or service provider to take a look at those speakers. If after some servicing in person mentions the need for a new crossover, you would have to send the speakers into service which we never recommend. But, crossover networks are not purchasable by consumers. So this present a dilemma.

 

[sarumbear]

It is highly unlikely and exceedingly rare that it would be your crossover network. But here is the problem, in order for you and us to really know that, you'd need a dealer or service provider to take a look at those speakers. If after some servicing in person mentions the need for a new crossover, you would have to send the speakers into service which we never recommend. But, crossover networks are not purchasable by consumers. So this present a dilemma.

That is not a dilemma. It is flat out refusing to service the speaker. How long ago your purchased it? Their warranty is 5 years.