What could be wrong with my LE85 + H91 horn?

[FoolForARadio]

At first it was deteriorating foam and shot diaphragms, but I cleaned up the foam and put in 16 Ohm Radian diaphragms, correctly I think, but maybe not? They sound great with some music, but there is a distortion in the horn during some high loud passages, particularly noticeable in solo piano and soprano voices.

I disconnected the woofer and it's definitely a horn thing. I also removed the lens, so it's not a loose or broken lens.

I'm going to clean the magnet gap out again in case I missed something the first time and try again. But what else might the problem be? Any ideas? Someone suggested the problem might be in the crossover...? Or maybe I didn't install the diaphragm properly, although it seemed to go in pretty well.

Well, thanks for your help...

[hjames]

The most likely problem is crud in the gap - I'm not a pro but getting it really clean seems to be an issue often mentioned here.

Another factor - its not the factory diaphragm, its an aftermarket replacement, so the specs may not be the same and there may be some issues in response due to that.
DO you know if you had aluminum or titanium diaphragms before?
Do you know what the replacement diaphragms are?



At first it was deteriorating foam and shot diaphragms, but I cleaned up the foam and put in 16 Ohm Radian diaphragms, correctly I think, but maybe not? They sound great with some music, but there is a distortion in the horn during some high loud passages, particularly noticeable in solo piano and soprano voices.

I disconnected the woofer and it's definitely a horn thing. I also removed the lens, so it's not a loose or broken lens.

I'm going to clean the magnet gap out again in case I missed something the first time and try again. But what else might the problem be? Any ideas? Someone suggested the problem might be in the crossover...? Or maybe I didn't install the diaphragm properly, although it seemed to go in pretty well.

Well, thanks for your help...

[grumpy]

I'd also guess rubbing of the voice coil, whether on junk in the gap, an out of round
coil (or a stacking of tolerances... e.g., large dia gap, small dia coil), a tilted or
misaligned VC relative to the mounting holes (possibly bad, but I don't know if you
have any recourse in doing a DIY install).

I'm pretty sure I know the noise you're describing, as it is more noticeable on pure-ish
tones (exciting the "rub resonance" ... the mostly non-harmonic tones stand out more).

I've cured that at least once by re-aligning the voice coil with the mounting screws a
partial turn loose, until the racket stops... then snug down the screws and recheck.
Easier to do with the proper equipment... that pros, who do things like this for a living,
typically have in their shop.

[FoolForARadio]

You are right about the type of sound that sets it off - close miked well tuned vocal harmony (Tallis Scholars for example) and close miked solo piano (Glenn Gould, Well Tempered Clavichord.) Both are bristling with overtones.

Good to know about reseating the diaphragm - it's something to try.

I had the original aluminum diaphragms before but I never heard them except when they were already toast. The replacements (Radian) are also aluminum.

[Eaulive]

I agree with Grumpy, remove the diaphragm, clean the gap and clean the gap. Then when it's clean, clean it again :)

Make sure nothing rubs and is well centered.

If you have access to a variable tone generator, it's easier to identify and fix the problem.

[Earl K]

Radian Diaphragms ( as JBL replacements, IME ) are notorious for their difficulty at getting setup properly. ( I own 7 1225 types & 1 1228 ) . The difficulties are usually due to their sloppy tolerances ( for the guide hole diameter or the fastener holes / which are all slightly over-size ) .

One really needs test equipment to have any chance at success for a clean mounting .

<> EarlK

[FoolForARadio]

Just to follow through with this, I remounted the diaphragm, loosened and tightened things, moved it around, and things got better but never just exactly right. So I bought another diaphragm off the internet. It cleared the problem right up! Maybe I damaged the Radian when I installed it, although I wasn't aware of it. Now I guess I need to get matching diaphragms but I'm so happy to have the rubbing noise gone that I can live with the mismatch - I can't even hear it, but maybe with time or different music I would.

Anyway, thanks for all the help!

[Audiobeer]

Is it just me? I actually like the sound of the Radian over the JBL Titanium.

[Rolf]

My experience is to use original parts.

[macaroonie]

Just to follow through with this, I remounted the diaphragm, loosened and tightened things, moved it around, and things got better but never just exactly right. So I bought another diaphragm off the internet. It cleared the problem right up! Maybe I damaged the Radian when I installed it, although I wasn't aware of it. Now I guess I need to get matching diaphragms but I'm so happy to have the rubbing noise gone that I can live with the mismatch - I can't even hear it, but maybe with time or different music I would.

Anyway, thanks for all the help!

Hey if you want to check on your speaker system in general for rattles and buzzes download a slow sweep tone from http://www.nch.com.au/tonegen/index.html press the get it now and you will get a trial version. You will need to define a time for the sweep , ie a minute and a range. If you are only looking at the HF 500 - 20k is good.
Either playback from your computer or burn a CD. If you are running straight from your computer you can incrementally increase the frequency till you hit the offending buzz . At that point you leave the tone running and attend to the mechanical issues ie centering the dia.
Low watts for this I should add.
Any oddities will show up very clearly.