[Lost81]

Hi all,

I have been having this weird problem with my sound system.
When the volume is turned up (beyond 85 dB) in tracks where there is high frequency content, the right tweeter occasionally experiences intermitten distortion, crackling, drop outs.

This only happens in the right tweeter.

Now, I am trying to isolate the problem.

Based on previous experiences with troubleshooting, I am leery of blaming this on the AKSA monoblock responsible for the tweeter.

I opened up my speakers, and I discovered an oddity:
For the Mission 753 Freedom 5 speakers, the folks at Mission designed the 3rd order, 3-way crossover in an unusual manner. When the speakers are bi-amplified, the Hi-Freq pair of binding posts are responsible ONLY for the 1" silk-domed, ferro-fluid cooled, tweeter.

The Low-Freq pair of binding posts lead to the mid-range and woofer.

Now that is weird.

That essentially means that I have a pair of 100W Nirvana AKSAs driving a 1" tweeter (140W into 6 ohms, actually).  

Is there such a thing as OVERDRIVING a tweeter?
The tweeter is protected by an inductor, 2 resistors, and two film capacitors.

Anyways, I thought that the problem is either the tweeter in the right speaker, or the monoblock amplifier, but right now I am playing the soundtrack to "The Last of the Mohicans" (Varse Saraband version) at 95 dB now, and there is NO DISTORTION. Maybe I have some crappy recordings?

Any help in isolating this "problem" is highly appreciated  

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A related question I have is:

Is it possible to separate the physical components of the passive crossover for the midrange/woofer, install a 2nd pair of binding posts, and passively tri-amp in this manner?

Please do not direct me to to active crossovers, as I have no wish to go that route.

My unschooled hunch at this moment is this:
Since the speakers can be bi-amped by removing the bridges between the Low-Freq and Hi-Freq binding posts, why can't the same be done for the mid-range and woofer?

Thanks and have a merry christmas!


Cheers,
-Lost81

[JohnR]

I'll bet a round of beers that it's an interconnect

Try jumpering the connectors on the speaker and driving with just one amp.

[PSP]

... and you can always switch around the monoblocks and see if the problem stays with the speaker or moves with the amp...

I had a bad tweeter diaphragm once... I would get breakup type distortion, but always at the same point in the music... it just couldn't handle certain sounds.  I replaced the tweeter diaphragm it's been good ever since.

Good luck,
Peter

[andyr]

A related question I have is:

Is it possible to separate the physical components of the passive crossover for the midrange/woofer, install a 2nd pair of binding posts, and passively tri-amp in this manner? ...

Hi, Lost,

If you have a 3-way speaker (base, mid-range and tweeter) then, yes, you could rebuild the crossover to have:
* a base LP section
* a mid-range BP section, and
* a tweeter HP section (which is already there).

Then you could put a separate amp on each - voila, passive tri-amping!    

However:
a) you would probably be doing yourself a favour if you replaced all the stock components with high quality components (if the Missions are anything like Maggie crossovers!).
b) bring the crossover outside the cabinet because the high-quality coils are likely to be much larger than the stock.

Regards,

Andy