How to determin suitable replacement driver

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thebisch

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Joined 2010
#1
Hi, how does one go about finding a suitable replacement driver for a speaker that the manufacture doesn't support any longer?

I have a pair of Mirage M-460 speakers that to me sound pretty nice. I did manage to blowup one of the drivers though (don't ask...).

Mirage does not support this speaker any more and does not offer replacement drivers.

Anyone have any advice for a reasonable priced replacement that would be suitable for this speaker? I would hate to have to throw these away. They are in great shape, and the cabinets are pretty beefy in the build dept.
 
#4
Was it the woofer that was 'blown' or the tweeter?? A two-way ported with a 7-8 inch driver...the tweeter as I have read is an old out-of-production Vifa brand. IF your tweeters are still working & it is the woofers that are out....Since it is ported it kinda complicates things. We need to match impedences...not an issue as most are 8 Ohms, Sensitivity, frequency coverage (35-2.5 K)??? So lets have at it. Since we don't know sensitivities, shoot a little low, we can pad down(Add an L-pad)the tweeter to match it up. This will be done by ear. If we pick a driver too high one really can't pad down a woofer....so we shoot for around 86-88 Db, kinda low here. Next we pick & choose as wide a F coverage as you can find..the crossover will do the rest. And here is the biggie....chances are whatever driver you choose it won't match up for the fixed internal volume and the fixed port tube. So the logical & easiest solution will be sealing up the port , changing the system to a sealed design. Given the complexity of ported design this would seem the best option. With the fixed sealed volume your Bass performance could sound quick with good transient response, with the bass not wanting to reach way down. This would be a box "too large" with a system Qtc approaching 0.5. With the sealed box too small the Bass will be pronounced & sounding "muddy" with too little control of transients....a Qtc approaching 1.0 or over. WE will be aiming for a compromise between the two extremes, a Qtc of .707 You will of course need to replace drivers in both enclosures so you don't have left to right differences.

-----------------------------------------------------------Rick........

_______________________________________________
 
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#5
Wow, what a response, most of which is over my head! LOL! Yes, it is the woofer that is blow. The Tweeters work. And yes, I was planning on replacing both woofers.

So in other words, you propose to basically redesign the speaker as an acoustic suspension design. Sounds good to me, as long as this can stay a budget project.

If it matters design wise, I like laid back, non bright sound. I also prefer sound staging behind the speakers rather than up front. I also don't mind a mid bass/upper bass hump, probably due to the mostly crappy classic rock recordings I listen too. The system as of now (if it matters) is...

Speakers toggling between...
B&W 604s2 (these are probably out the door soon. I find them too fatiguing and forward for my tastes)
Advent Heritage (pretty good, but strange to me in the mid range)

ATI 1502 amp
NAD 1020 preamp
Marantz CD-63SE (super screechy sounding)
Panasonic PD-65 Blu Ray (less screechy than the Marantz, but more closed in sounding than the Marantz)
Denon DP-47f turntable
Old original P mount Blue Point cart.
 
#6
OK.....so look thru the site Parts Express: the #1 source for audio, video & speaker building components, go to the selections for 8" drivers....some are way pricey, some not too bad.
keeping within your budget, selecting as wide a band as possible(Frequency range) and a sensitivity around 88 Db. All these specifications are listed, as are others......next, as you remove the bad driver make some measurements & calculations of the internal volumes.....to get a value from which we can derive the sealed performance of any one driver that you've selected.
There are some simple formulas we can derive values of Qtc (Total system performance) from the 'other' specifications of your prefered driver.

______________________________________________________Rick........
 
#7
Hi,

Substituting bass/mid drivers for a 2-way is nearly always a wing and a prayer.

I've done it successfully, with carefully chosen similar drivers, but its risky.

I'd say its a toss up between this :
MCM Audio Select 8" Carbon Fiber Die-Cast Woofer with Rubber Surround - 75W RMS | 55-3550 (553550) | MCM Audio Select
http://www.mcmelectronics.com/content/ProductData/Spec Sheets/55-3550.pdf
and this :
MCM Audio Select 8" Poly Cone Die-Cast Woofer with Rubber Surround - 70W RMS | 55-3190 (553190) | MCM Audio Select
http://www.mcmelectronics.com/content/ProductData/Spec Sheets/55-3190.pdf

The two drivers are very different at first sight, the best one is the one
most similar to what you have, and that depends on the amount of BSC
built into the crossover. Note that the 89dB driver is actually more
sensitive in the c/o region than the 92dB driver, these things matter.

Of the two I'd say the poly driver is the most likely to generically work
well, but the other driver could replace a more unusual fitted driver.

Both will work well in your cabinets with the original vented tuning.

Really what you need to do is listen to the working unit full range and
decide which of the two very different frequency responses of the above
drivers is most similar, dark and laid back for the carbon, or lighter and
more lively for the poly unit.

Its still a risk, but it will get your speakers working, never the same
as original though. You may also need to adjust the tweeter level.

rgds, Sreten.

It is also possible the fitted drivers are a known quantity, pictures help.
 
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