HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

Ok, so, I have the top and mid sections of the Cubix-Pro and from day one I've struggled a bit with the tweeter output. On sibilants they were really, really sharp and I stated as much on the forum at the time. The Doc actually came to my house to have a look/listen and see if there was anything that could be done. He brought with him a can of Plasti Dip and duly gave each tweeter a coat. It certainly tamed it to a degree and after listening for a wee while he left, suggesting that I could repeat the process if I so desired. Well I did actually apply a few more coats and have managed to reduce, but not eradicate the problem. I don't want to just keep layering on Plasti Dip as I'm sure I'm losing resolution. I'm starting to think that maybe the tweeters used, (don't know what they are but knowing the Doc they won't be expensive), are just a bit "uncouth" for my taste and I'd like something a little "sweeter". I never had this issue with my Cube 1's though. I'm quite capable of swapping in new tweeters but don't want to just launch into it blind, so what do I need to consider? Is it just a case of matching the electrical specs like impedance, etc, or is there more to consider? Is there anything else I can try first? Cheers.

Not sure what tweeter were used as I believe your one were build "before my times" ( as a part of 3 stack for Applemark? ) but if there were fitted as the later ones changing it will require a lot of effort as glue used is kind of permanent and you need to be very careful not to damage the acrylic case - you might be lucky and Doc might use Bison Kit then changing it will be much easier ;]

I use a scan speak d2904. Not cheap £114 quid each, but I don't have any sibilance.

I've also used a seas model at £50 quid each with no problems.

I did not dope any of them.

With the celestion modidded speakers I used a 7ohm resistor.

With the wharfedale model I now use, I used no resistors just a cap.

The doc used 2 tweeters a cheap Chinese one and a £50 one(I've forgotten make) don't know which one you had.

If you don't want to go down the route of a new tweeter, you can increase the ohms of the resistor (again don't know yours) or you can change the value of the cap to increase the frequency at which the tweeter kicks in.

Ithilstone wrote: ↑Thu Apr 23, 2020 10:55 am Not sure what tweeter were used as I believe your one were build "before my times" ( as a part of 3 stack for Applemark? ) but if there were fitted as the later ones changing it will require a lot of effort as glue used is kind of permanent and you need to be very careful not to damage the acrylic case - you might be lucky and Doc might use Bison Kit then changing it will be much easier ;]

Would a hot air gun help for softening the glue to remove the old tweeter, or would it be a waste of time due to the type of glue used?

And how careful would you have to be with a hot air gun to avoid damaging the acrylic of the speaker cabinet?

RD's favourite tweeter for Cubes was the Visaton G20SC costing around 50 pounds.

A very sweet and clear sounding unit.

When I refurbished the 1990's Cube3 boxes he recommended them and they sound really good.

Hmm, yep that looks like it. Wonder why I get this sibilance then? I realise that I may just be more susceptible to it possibly?
Going to be talking to Thomaz at some point so hopefully might have a direction to move in. Cheers.

I think sibelance is one of those things you have or don't have and everybody hates it.

I to hate the dread S........ . My experience says it's usually the cables - needing a good run in.

My friend had a set up to die for until he moved house. The room was essentially the same shape as his former house, just a little smaller. He was having terrible trouble with his system. Sounded like it needed run in again. Turned out it was a large coffee table sitting between him and his speakers. Moved the table and "hey presto" all back to normal.

Moral - it might be the room not the system?

I'm not a speaker expert, but have played around with various tweeters in various speakers and have achieved unpleasant sibilance from all of them before I'd attenuated their relative level to my tastes.
My guess is your problem is due to the level of your tweeter being too high for your ears.

Can you confirm this by attenuating it digitally? (Maybe some digital parametric EQ roll-off from around 4kHz?) You could do it subjectively, on the fly while listening to music. If it does, you could permanently fix the issue with attenuation via an appropriately rated resistor / L-pad.

If instead you want to try a different tweeter, do check how the sensitivity of a possible new unit compares to the tweeter you have now. In my limited experience, those figures are not the be all and end all, but fitting a new tweeter with a higher sensitivity may mean that the sibilance problem actually gets worse.

EDIT: Just noticed your sources in your signature. No computer audio source. That makes digital attenuation more difficult. Do you have a laptop you could connect up, just via the headphone socket? You could download JRiver Media Centre on its free 30 day trial and use the parametric EQ tool integrated into that while playing one of the better included Radio Streams (e.g. Radio Paradise). So you wouldn't need any local audio files.

Thanks Doc, and others, for taking the time to respond.
Managed to have a chat with Thomaz, (it is spelt with a z isn't it?), and he was pretty horrified by the Plasti-dip tweak! We are going to spend some time passing pictures and information back and forth to see if we can find out what's going on and what I can do to correct it. Will probably get some replacement tweeters at some point anyway, to remove the Plasti-Dip from the equation. In the meantime we will be looking at resistors and capacitors etc