MCM 55-2421 came unglued in a T18. What alternatives??

[Gregory East]

You found out the hard way precisely why I recommended L brackets. Sorry, I assumed you already had enough fun with t-nuts to see it coming.

[But it Hertz]

Has the driver or the box got any info on it?

You might track down (eventualy) that Brand X sub is loaded with blah blah driver, and get some TS specs if it has some and go from there...

No, this fictitious scenario is completely blind. But you must hurry! The punters are arriving soon and they are in the mood for dancing!

[shawn_g]

Nice work. Glad to hear that it all worked out.

[Grant Bunter]

Has the driver or the box got any info on it?

You might track down (eventualy) that Brand X sub is loaded with blah blah driver, and get some TS specs if it has some and go from there...

No, this fictitious scenario is completely blind. But you must hurry! The punters are arriving soon and they are in the mood for dancing!

Fictitious or otherwise, look for any info and research.
If you can't find anything at all, buy a driver that fits and has TS specs and you can start to work it out from there.
Or keep turning it up with the DMM on it until you get to "oops that was to far".

16 hours until I start my load in. Plenty of time...

Great result for you BTW

[Gregory East]

The JBL gto804 is good to 40 volts above 40 hz only in cab)

If this is true, that's pretty awesome!

This leads leads me to talk about another thread running in my brain:

After "enjoying" a BFM near social death experience last night... say someone gives you a subwoofer in a box but you have no idea what the design or driver is. How do you go about figuring out what your limits are without damaging it?

voltage limit relates to impedance. 40v is 200w for 8ohm. Plenty loud!

Direct radiators you can push to the limit by ear. No such luck with horns. Dunno about bandpass.

You seem very concerned with the friendly correction of your error.

[But it Hertz]

You seem very concerned with the friendly correction of your error.

Maybe just a little

[Bas Gooiker]

I was in no mood to take it out and fix so in a huff I put a dash of PL over each gasket joint. I was CRAZED at this point. I don't mind admitting I did a little dance, stamped my feet and shouted at the walls.

Good to hear you you had fun making your modifications...
Great you did not give up and so now you are rewarded with a better then expected end result.

[But it Hertz]

So I made a couple of SPL charts today. Here is the setup:



The sound card is a Beringer UCA202, the SPL meter is a checkmate CM-140, the DSP is miniDSP and I used REW to take the measurements.

Before I started the sound card was calibrated and the CM-140 calibration file was used as supplied by REW. C weighted.

This is the before Eq (red) and after (green) sweeps. If you were generous with this and squinted a little you could say it was relatively flat from 30Hz to 100Hz... but how ever you say it you can see that with a little more time & effort I could definitely get that curve flatter.

I have the cut off frequency set at 90Hz when in use.



This is what the miniDSP settings page looked like when I was done. Took me about an hour messing around to get this far:



Now of course I'm going to put it back into the corner and will have to start again... but that's all part of the fun isn't it?

[But it Hertz]

This is the sub in the corner. I have a room node causing a big dip around 55Hz.

The purple line is the T18 in the corner with the Eq I applied to make it flat in the middle of the room (same as above). Note it still had the cross-over enabled when I took this.

The red line is with all Eq and the cross-over bypassed

The green line is with new Eq for the corner.

[rebar]

This thread makes me second guess my decision on MCM 55-2421's for my truck tuba's..

Is there a way to make the TrT enclosure more adaptable for other drivers so I dont go through this when/if I upgrade drivers?

And is there a thread on how to strengthen the weak spider glue joints of the MCM 55-2421 ?

Thanks !

[Grant Bunter]

This thread makes me second guess my decision on MCM 55-2421's for my truck tuba's..

Is there a way to make the TT enclosure more adaptable for other drivers so I dont go through this when/if I upgrade drivers?

And is there a thread on how to strengthen the weak spider glue joints of the MCM 55-2421 ?

Thanks !

I can only recall a couple of threads in my time here about the MCM spider letting go.
I couldn't even begin to guess how many cabs have been made up with MCM drivers in the same amount of time, but say it's 100. That's would = a 2% failure rate for a cheap driver.

Why think about "upgrading"?
Buy what you want to put in and then you don't have to bother.

You have to remember, invariably it is the design, and not the driver, that dictates response.
In that regard, it doesn't matter what driver you put in, out of the recommended drivers.

I think you'd have to be unlucky to get an MCM driver that fails...

[rebar]

Why think about "upgrading"?
Buy what you want to put in and then you don't have to bother.

You have to remember, invariably it is the design, and not the driver, that dictates response.
In that regard, it doesn't matter what driver you put in, out of the recommended drivers.

I think you'd have to be unlucky to get an MCM driver that fails...

Failure is when I upgrade. If the TrT's with 55-2421's keep me happy Ill be all set. But if something happens, I would consider a upgrade. I'm guessing L bracket mounting is the most flexible in that situation.

[jimbo7]

This thread makes me second guess my decision on MCM 55-2421's for my truck tuba's..

Is there a way to make the TT enclosure more adaptable for other drivers so I dont go through this when/if I upgrade drivers?

And is there a thread on how to strengthen the weak spider glue joints of the MCM 55-2421 ?

Thanks !

I had the exact same problem with my mcm. I just smeared some epoxy on it and let it cure a day. It worked great even after some hard use the next day at a halloween party.

[rebar]

This thread makes me second guess my decision on MCM 55-2421's for my truck tuba's..

Is there a way to make the TT enclosure more adaptable for other drivers so I dont go through this when/if I upgrade drivers?

And is there a thread on how to strengthen the weak spider glue joints of the MCM 55-2421 ?

Thanks !

I had the exact same problem with my mcm. I just smeared some epoxy on it and let it cure a day. It worked great even after some hard use the next day at a halloween party.

After hearing about two failures Ill be sure to build my TrT so that it excepts the recommended drivers. Dayton DCS 205-4, Tang Band W8-740, JBL GTO 804

[DJPhatman]

After hearing about two failures Ill be sure to build my TrT so that it excepts the recommended drivers. Dayton DCS 205-4, Tang Band W8-740, JBL GTO 804

Don't forget about the Infinity 860W. Very reasonably priced and used with great success.

Make 6-8 mounting L-mounting blocks so you can change it out without much trouble.