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Proac problem: tweeters or crossover?

Recently, something moved me to listen closely to the tweeters, and when I couldn't hear anything I hooked up the speaker cable just to the tweeter binding posts. I can't say there was no sound at all, because there was the faintest of recessed, tinkly sound that didn't seem to vary much with the level of the volume control.

I called up Modern Audio and they told me just to get the Scanspeak D2010s from Madisound. I soldered them in this morning. Now the new tweeters are a bit louder than before, but not nearly as loud and not as strong on the higher frequencies as I would have expected. They still sound subdued, recessed and tinkly/jangly, but not as much as before, and there's a bit more change in level when varying the volume control. This is as always with the cable hooked up only to the tweeter binding posts.

So...is this how they're meant to sound, or is there a problem with some component in the crossovers? If there is, it must be the same in both speakers' crossovers. I wish the result of the change-over had been less ambiguous: either virtually no sound, or a great improvement. Instead, it falls somewhere in between, but the result makes me think that I haven't solved the problem.

BTW, the Response 2.5s must be ~17 years old. Custom yew finish bought new from Accutronics in Ann Arbor in 1998/99. The mid-woofers still sound great.

Does anyone know what a Proac tweeter driven in the way I've described should sound like when it's functioning correctly?
twoleftears

Showing 5 responses by twoleftears

twoleftears's avatar
twoleftears OP
5,320 posts
 
Thanks for responses.

I did install the new tweeters carefully, and they definitely are in correct polarity. I noted that the internal hook-up cable was labelled Bandridge Superflex 2.

The mid-woofers sound great, so it isn't the electronics.

I'm using Synergistic Research Signature 2/3, and I've hooked both the thick and thin runs of cable up to both the tweeter and the mid-woofer binding posts, individually, to confirm that everything's running as it should.

Basically, my questions boil down to this. If a tweeter is blown, or has failed from age, will it pass any sound at all, or can it pass a little "throttled" sound? Likewise, if a component in a crossover is going bad or had gone bad, depending on what that component does, can the mid-lows be left totally unaffected, while the highs are impacted in the way that I've described in my original post?

I have to confess to being baffled and frustrated from the results I've got so far. When I installed the new tweeters, I either expected no improvement (=crossover the problem) or 100% improvement (=solved!). Instead, I got about a 25% improvement. I'm still struggling to understand how this could be, unless Proac tweeters, when run on their own, sound very different from how you'd expect a tweeter to sound when not underpinned by the other drivers.
twoleftears's avatar
twoleftears OP
5,320 posts
 
P.S. I'll try and describe what I'm hearing from the tweeters.

The basic sound level (volume) is a total mismatch with that of the mid-woofers, if they were running. The tweeters are at a much lower level. It's hard to imagine that when both drivers are running, the tweeters would contribute more than 2% to the total sound.

The quality of the sound coming out of the tweeters is very distant, like it's several rooms away; it's thin, tinny, tinkly, jangly, disembodied. Also, curiously, it doesn't seem to have a lot of upper-octave energy.
twoleftears's avatar
twoleftears OP
5,320 posts
 
Almarg: will do re. test CD. I should have added earlier that I've inserted an Ayre AX-7e into the system (that led to initial scrutiny of the speakers).

Zd542, as per original post, Modern Audio, the distributors for Proac in the US, told me to acquire the Scanspeak D2010s. When I queried them as to whether they were identical, or whether Proac did some mods to them or not, they claimed that they were identical. For a while there, there was quite a lot of "cloning" of the 2.5 in DIY designs, so there's a good deal of discussion of components on the web.

The SR Signature 2/3s are like this: at the amplifier end, there is a spade, immediately after which the cable splits into two, so there are two separate runs, physically, all the way to the speaker. I don't know what's going on inside, but the run for the woofer is thicker, which is the only way you can tell the two of them apart.

Dover: according to the web, the 2.5s use Ansar Supersound caps. I'm keeping my fingers crossed that there's nothing broke.
twoleftears's avatar
twoleftears OP
5,320 posts
 
For anyone coming across this thread I thought I'd add the following information.

I recently had a very useful conversation with an highly knowledgeable technician. He expressed surprise that both speakers were equally affected, until he enquired as to whether they had been in storage for any length of time. Indeed, they had gone essentially unused for quite a while before being brought back into service recently. According to him, while electrolytic capacitors can just fail with age, they are more likely to go bad if they are not juiced or goosed from time to time with some signal from your amplifier. Who knew? He added that the effect of capacitors going bad is like soldering a resistor into the signal path, resulting in a much lower level signal to the tweeters and just a faint sound coming out of them, which is exactly what I am experiencing.

They'll be off to him for repair soon, and I'll report back in due course.
twoleftears's avatar
twoleftears OP
5,320 posts
 
Yes. I realized that shortly after I posted. In the tech's defense, we only had a telephone call, so it wasn't "eyes on". I gather that the Ansar Supersounds are polypropylene. I'm assuming, unless someone can tell me otherwise, that polypropylenes can go bad too and act in the same way (essentially, as a resistor) as electrolytics.

I find this theory about the problem highly plausible, because when I went back and tested the newly installed new tweeters again, the sound level was back to where it had been when I realized I had a problem, i.e., there was just a very faint, throttled sound coming from the tweeters, pretty much no matter what the volume on the amplifier was set at.
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