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
Did you make sure you connected the new tweeters in the correct polarity ?

Good Listening

Peter
I was just about to say polarity and then read your response, lol. I have had many sets of Proacs since the 90's (just sold off three pair) and everytime we worked on the tweeters, we were so careful to hook them back up correctly as the first time we didn't and it sounded similar to what you are sharing. In anything that old, it could be a failed component in the crossover. Are you able to hook them up to another system to see if it's the speaker or the electronics?
Hard to know exactly what you're hearing but tweeters alone don't make a lot of the sound when music is played. Assuming the crossover point is above 2kHz, there wouldn't be much information to produce as the majority of the music signal is below a the tweeters cutoff.
I once bought a pair of Eminent Technology speakers with a blown tweeter. I didn't notice until I was standing directly in front of the of the faulty speaker and noticed no energy from the tweeter ribbon.
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.
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.
I recently had some Proac EBS with no tweeter output. The Solen caps in line with the tweeter had failed - very unusual for a polypropylene cap.
There's a couple of things to consider here. The first is that the new tweeters are going to break in, and will sound different when that happens.

"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."

Those are 2 runs of completely different cables, they're not just thicker. Different materials are used. You need to try the speakers with either 2 runs of the exact same speaker cables, or 1 run and use the binding post jumpers.
Those cables that you have are a band aid type fix for a speaker with a very harsh tweeter like B&W. You don't need that with the 2.5's.

It wouldn't be a bad idea to list your entire system.
Zd542,
"Break in" for tweeters…Really? I am sorry, but please don't provide such advice when clearly you know nothing about how electronics or transducers work.

Twoleftears, this is exactly how normally properly functioning tweeters sound when operating w/o a woofer.
"03-06-15: Bojack
Zd542,
"Break in" for tweeters…Really? I am sorry, but please don't provide such advice when clearly you know nothing about how electronics or transducers work."

Sorry about that. Can you tell me what line of speakers you design? You didn't say.

Twoleftears,

I forgot to ask in my other post if the new tweeters are exactly the same as the ones you took out?
Twoleftears, as you may be aware tube amplifiers having output transformers should not be operated without a speaker or equivalent load being connected, especially when signals are being put through them. Assuming you are still using the Cary SET amp listed in your system description, it occurs to me that when you connected the amp to just the high frequency section of the speakers you were running the amp unloaded across those parts of the spectrum where the great majority of the energy of most music is concentrated. I say this given that the crossover point of your speakers is a bit higher than 3 kHz, as shown in Stereophile's measurements, and the rolloff of the high pass part of the crossover below that point appears to be a fairly rapid 18 db/octave.

Which leads me to suggest two things:

1)Don't do it no more :-)

2)I'm not certain of this, but it seems to me to be possible that the anomalous sonics you heard when only the high pass sections of the speakers were connected might have been the result of amplifier misbehavior resulting from the improper loading. So I'm not sure that any of those observations were meaningful.

And perhaps the differences you observed with the new tweeters vs. the original ones were simply due to what would under normal circumstances be inconsequential differences in their parameters.

What I would suggest is that with a little Googling you should be able to find a test record or CD you can order which has a set of 1/3 or 1/2 octave warble tones, or something similar, the set of tones covering the entire audible spectrum. That would allow you to very readily tell whether the tweeters and their associated crossover elements are working properly or not, which I don't think any of us can say at this point with any certainty.

Good luck. Regards,
-- Al
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.
With the crossover at 3kHz as Almarg stated, I think what you are hearing is normal. I had a pair of Paradigm Studio 60s that experienced a tweeter failure, the dome disintegrated. When I replaced it I first listened to the tweeter separately as you are doing and heard what you described. I compared it to the good speaker's tweeter as I was concerned.
You could measure the resistance of the tweeter and see if there is any difference between speakers. If there is a difference then there may be an issue with the crossover, but as you say both sound the same I doubt it. As for break in, not the issue here.
The real question is, how do the speakers sound when being played normally? I think you purchased an extra set of tweeters.
"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."

What they did was take 2 separate pairs of speaker cables and terminate them at the amp end with the same spades for easier connection. Otherwise you would have to double up and put 2 sets of spades in 1 binding post because most amps only give you 1 pair to work with. Since Synergistic always recommended using the 2's and the 3's together, they ended up taking the exact setup you have with the 2 pairs terminated together at the amp end, and wrap both pairs in 1 sleeve, making it look like one pair of cables. They renamed it the Signature 10.

What I said about them in my first post still applies. Given your problem, and how different those speaker cables sound from each other, I wouldn't want them in the system until you solve your problem. So you can either use different cables, or just connect 1 of the 2 pairs of the Synergistic to the speakers and use the binding post jumpers. Just be sure to cover the spades on the cables you don't use. And it doesn't matter which pair you use. Try it both ways and pick ones that sound best.

"The real question is, how do the speakers sound when being played normally? I think you purchased an extra set of tweeters.
Timrhu (System | Reviews | Threads | Answers | This Thread)"

That's a good question. After reading your post again, I can't tell if the problem exists during normal operation. A assume there's a problem otherwise you wouldn't post.
Regarding my suggestion of a test record or CD providing 1/3 octave warble tones, Stereophile's Test CD 3 appears to be suitable (specifically tracks 17, 18, and 19), and is available here. Further description is provided here.

A possible limitation of that particular test CD, though, is that as far as I can tell it may not provide separate tones for the left and right channels. If so, and given that your Ayre integrated amp apparently does not provide a balance control, you would probably have to disconnect one speaker, or one input channel to the amp, in order to accurately assess the other speaker.

Good luck. Regards,
-- Al
You could try to replace the two capacitors in the XO, you can find suitable replacements here 4.7uF Capacitors and here 3.3uF Capacitors The XO calls for a 3.4uF, the 3,3 will suffice but if your a stickler bypass it with one of these 0.1uF bypass Cap

It would be veery unlikely that the capacitors have failed, however like Dover
I can recall some Solen Caps fail many years ago.

Best of luck

Peter
Having sold Proacs for 24 years
It could be a simple fix.
Unscrew and remove both top tweeter section knurled binding post nobs.
Insert carefully a small blade screwdriver into the hole and gently tighten the top binding posts clockwise a half turn till snug if its still loose go for another half turn but do not over tighten.
If this seems to get back your volume you are set.
If its still intermittent removing the woofer and get into the crossover board connection area and clean up the star washer x over board area where the binding posts meets the board will complete this.
Hope this works for you
JohnnyR
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.
Good luck and keep us posted.
Hello Twoleftears,
I haven't chimed in before now because I saw that Peter has given you solid advice on what to look at... I'm replying now to give a quick response to your last post. Proac doesn't use any electrolytics in that speaker. An experienced tech would look these up and tell you that. Just don't want you to go down a road of a lot of expense without solving this.
Tim
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.
I have seen a bad Polypropylene cap, but it was bad from the factory, I've never seen one go bad. I would suggest, you go more the way that Al suggested, get a test tone cd and a decent mic and measure frequencies at about a 3ft away... turn your volume up until you measure 90 db or so, then without changing your volume, change the frequencies and measure... I'd probably check from 2k to 5k in 500hz brackets. All should range from 87 to 93.
If it all falls in that range, your tweeters are fine. I think we all have been tricked into thinking there are problems... on the other hand, if it measures weird then at least you have a frequency that gives a barometer of where to look. Odd things happen, you could have gotten tweeters with the wrong diaphrams...
If you plan on continuing in the speaker game, I would highly recommend purchasing a LCR meter
Could it be that you are just unfamiliar with how a tweeter sounds on its own with a crossover in front of it? To the inexperienced it can sound like you describe. If you play the speakers with input to both sets of terminals i.e mid woofer and tweeter does it sound normal ?

Jonny R from audio connection gives some good advise on terminals however don't tighten them from the outside, open them up and tighten the nuts on the inside. Proac use Mitchell binding posts they have a knurled shaft you don't want to loose the grip they have in the mdf plate that they are mounted in.

Best of luck

Peter
PNB, that's also great advice. I have had to do that with a few different Proacs that either I owned or my friends have owned. Wish that was fixed by them in the 90's when they first encountered the problem.