Blown woofer in Quest

[evvster]

Had a few nice chats with ML yesterday trying to track down a replacement woofer for my epically blown Quest woofer. No luck there, and they don't forsee having any in the foreseeable future.

I'm here with two agendas. The first would be figuring out if anyone had a woofer they could sell me. (can't find a fingers crossed emoticon)

The other agenda would be sourcing the wealth of knowledge here to find a suitable replacement that would sonically match the other channel in the hopes of not having to swap both (though I'm not opposed to that)

I ran across a couple of posts that referenced swapping out cones and bi-amping to use the lower cabinet as a subbox, but no one seemed to be swapping to keep original characteristics.

Any help would be greatly appreciated!

If anyone even had exact specs on the cones that are in there past the response numbers ML gives in the manual (excursion etc...) that would be awesome!

Thanks! Evan

 

[Thegainster]

I'll be no help with the ML part of this problem but... I talked with Ty at length this week and he is a wealth of info on speakers and cabinets. He may be able to help in the replacement end of this. Good luck. Sorry to hear about your troubles.

 

[evvster]

Does knowledge think I'll have any hope of swapping something in that will match the original on the other side or am I in for two swaps?

 

[Tosh]

I'm not familiar with the Quest, so I don't know if the 12 inch woofer is in a sealed or ported box, or what its impedance (Ohms) is. If it's sealed, finding a replacement is easier.
On the still functioning woofer, what is the DC resistance? If it measures around 5 Ohms, then it's nominally an 8 Ohm woofer; if it measures around 3 Ohms, then it's nominally a 4 Ohm woofer. You will also want to exactly measure the outside diameter of the woofer basket to ensure the replacement candidate fits the hole and any counterbore. Pics might help...

 

[evvster]

Sounds good! I'll break out yee ole ohm meter this afternoon and start pulling some good info. We are certainly looking at a sealed box unless ML has some incredibly stealthy port somewhere. (and it certainly performs sonically as a sealed box)

 

[Tosh]

My educated guess is the original is a 4 Ohm woofer, which the replacement also needs to be for the stock crossover to work correctly. I notice that Parts Express has two 'Goldwood' brand 4-Ohm, 12 inch woofers that should work 'OK' spec-wise, if they will physically fit the opening (and they're both on SALE through TODAY!)

option A ($38):
Goldwood GW-1244
MOUNTING INFORMATION
Overall Outside Diameter 12.00"
Baffle Cutout Diameter 11.00"
Depth 5.8125"
# Mounting Holes 8

option B ($53):
Goldwood GW-12PC-4
MOUNTING INFORMATION
Overall Outside Diameter 12.25"
Baffle Cutout Diameter 11.125"
Depth 5.375"
# Mounting Holes 8

Madisound also has the Goldwood GW-1244 at a higher price. I don't know who Goldwood is, but I suppose the fact both PE and Madisound has carried them for years is an 'endorsement' of their quality....?

 

[Solo]

I wonder if you or anyone else has found a replacement for the Quest woofer? I have a set of Quests that I bought new about 21 years ago and I had a woofer failure in the first few months (voice coil rubbing on magnet) and at that time I bought a new woofer from ML. I still have the original and suppose that someone might be able to repair the voice coil, but don't really know. I'm just thinking ahead to the day when one of the woofers dies again.

 

[Gordon Gray]

Evan,

Absent access to the original part, recommend replacing both woofers.

GG

 

[Sambob2]

I agree with Gordon's comment.

Without a direct replacement from the original manufacturer for the Quest's, I would replace both drivers.

There's so much more to matching a speaker than just the physical size and impedance - Free air Resonance, Q, Frequency response, flatness or variation over frequency, sensitivity, sound pressure level, power level capacity, damping factor, and many more...

As Tosh mentioned above, if you do choose to replace both drivers (highly recommend), you will need some physical dimensions from the cabinet and the speaker manufacturer to make sure it will fit, otherwise be prepared to modify the opening.

There are many choices of raw drivers to replace with, however, you may want to look into purchasing two drivers from a parts list from one of Martin Logan sub-woofer systems.

 

[JonFo]

See if ML will send you the Thiel-Small (TS) parameters on the original woofer. ML purchased those from vendors like Eminence, so often there will be an existing stablemate that has close if not identical specs. If not, then it's now easier to find a close match.
Also agree, replace both woofers at the same time.

IIRC, the Quest and the Monolith had very similarly speced bass drivers. I recall finding several third-party parts that would do well in that application, but that was in 2006. I'm sure you've read my adventures updating drivers in my speakers, but as you note, I had the luxury of not caring about exact matches.

So it all starts with the TS specs of your originals.