QTR QR 15 (passive)

Well I have a suggestion for re-purposing those boxes (I agree they _are_ likely to sound fairly 'orrible if used in a "regular" PA system).

Use em as a full-range battery-powered system - drive em with 2 bridged channels (each speaker, or just one speaker) of a decent class D car ampfier - so 100-150W or so each - and they'll probably do OK .... by virtue of being relativley portable, and -  in which context expectations are different.

These kind of speakers _can_ be acceptable when driven well below their rated power. Up the power and cone break-up and crossover saturation will kick in a make em sound like a bag of nails.

odc04r wrote: Never hurts to open them up and have a look.

+1

Don't believe too much of the descriptions of these boxes. They're liable to describe things based on wht they _look_ like, rather than what they actually are :-)

...not others, me! I said it.

I have seen a fair few of these now and they have compression driver write on all the bumpf and on the box. Open it up and there's the rather large piezo. Now I'm not saying this one has one but it is an educated guess and I would say right 9/10. This box may be the 1/10. With any luck it is (hopefully)

So on the grounds it is very likely one I have advice on what to do IF it is.

Don't get your knickers in a twist sweetie... I am allowed to be wrong and I accept when I am. Just don't get so angry and jump on your keyboard. I would gladly accept "nope, opened it up and it's a comp driver... you was wrong mate, what should I do next?" The heat gets to us all sometimes... have a nice cold beer and relax!

It's not the piezo per say that's the bad sound... it's the gap it creates between the 15 and the lower roll off of the piezo that I find the problem with.

A piezo should roll off at around 3.5-4k and the 15 (if it can be helped) shouldnt play that high.


...anyway as suggested why not just try EQ and tame it a little.. I have found a shunt resistor in path of the very likely piezo helps ALOT! And then just raise the high pass of the box to around 50hz and play from there..

Make some £££ in the mean time and start hunting for some new toys.



Edited by mini-mad - 23 June 2017 at 3:26pm

Fingers crossed it is... I opened a similar looking one. Was a huge piezo. I hope it is a comp, will make Upgraging a tad easier

So... i opened one of them

and will get the pics up asap hopefully by the end of today, to me looks like crossover wired wrong
as the wires for input come straight of the woofer which is wired to the speakon

the only think i see wired to the crossover is the tweeter (thats what written on x over )
where it says woofer nothing wired to it

once the pics up you guys can have a look

OK…. you have a 1” compression driver and your “x-over” is just a HP filter with a resistor to drop the compression driver’s output level to approximately match the woofer.

The woofer is just left to roll off naturally; L1 (when fitted) would normally be in series with the woofer to form a “Frist Order” (6db/oct) Low-Pass filter to remove  the High frequencies going to the woofer.