# Diaphram help



## oabeieo (Feb 22, 2015)

Tonight I put the cd10nd Beyma CD on the full-size horn for fun and to try something I haven’t done in awhile. 

Both horns seem to sound ok.....they measured with RTA very similar, the right horn was a little weaker in the lower end of the horn (900hz to 1.2k) than the left. No big deal I was doing my normal tuning , and when I got to the part where I run 20/20 sweeps through entire left and right channels for furthering my measurements I noticed what sounded like the right horn sounded weak (very) in the low end response of the sweep and had a almost muffled like sound to the sweep. I compared left and right and right wasn’t as far off as I was hearing in the driver seat. 

So I thought maybe driver interaction, I muted the midbass and ran again. Same thing. I finished my tuning and the right side (the same side that sounded quieter) was about 2db louder than the left (which it should have sounded the same. 

I pulled apart the driver , pulled on voice coils and no separation, no burn marks on coil. All looks good no debris in gap. Put cap on and listened. Same thing. Cap off and tryed a better alignment on coil. Same thing. 


Is there any other way I could have a bad Diaphram or can a horn just sound totally different from other seat and maybe I’m just trippin. 
Something tells me something is wrong. But before I go spend another hundred bucks on a Diaphram I thought I would ask and see if anyone has ever heard of anything like this


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## GEM592 (Jun 19, 2015)

Hate to say it but if you think it's a diaphram it probably is.


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## oabeieo (Feb 22, 2015)

GEM592 said:


> Hate to say it but if you think it's a diaphram it probably is.


Yeah..... your probably right. 
I just not seeing it tho . I’ve inspected that thing it looks perfect 
I’ve got to be missing something or going bonkers


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## GEM592 (Jun 19, 2015)

oabeieo said:


> Yeah..... your probably right.
> I just not seeing it tho . I’ve inspected that thing it looks perfect
> I’ve got to be missing something or going bonkers


A slight change in the geometry, meaning the former is even slightly tweaked, would make it sound wrong. As you know, this could result from running them a little too wide, maybe even with an amp that is a little too small on paper, or just from normal use.

Maybe swap the diaphrams and check? That's alot of work but it might be definitive.


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## oabeieo (Feb 22, 2015)

GEM592 said:


> A slight change in the geometry, meaning the former is even slightly tweaked, would make it sound wrong. As you know, this could result from running them a little too wide, maybe even with an amp that is a little too small on paper, or just from normal use.
> 
> Maybe swap the diaphrams and check? That's alot of work but it might be definitive.


Okay maybe your on to something 

Which made me remember last time I had them installed I had them on a focal amp that would clip easy. That amp wanted like 5 full RMS volts in or it was gutless, when you would use the gain up on it would clip easily. I wonder if it’s maybe super tiny amount that I can’t see warped or something. 

Visually it looks brand new still. 

Okay fine. If someone else thought that’s a possibility than I’m not bonkers 
Fine I’ll suck up the hundred bucks for a new one. (Expensive diaphragm)
I might (if I’m lucky) find a genuine one on eBay for 60$


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## Eric Stevens (Dec 29, 2007)

If its a diaphragm issue you should be ale to see something wrong physically or measure something in the DCR. Its a simple mechanical device and problems are always evident from my experience. One thing is if the diapragm height relative to the phase plug is off it will have an effect on FR.

Have you confirmed its the driver and not something up the signal chain by swapping channels?


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## oabeieo (Feb 22, 2015)

Eric Stevens said:


> If its a diaphragm issue you should be ale to see something wrong physically or measure something in the DCR. Its a simple mechanical device and problems are always evident from my experience. One thing is if the diapragm height relative to the phase plug is off it will have an effect on FR.
> 
> Have you confirmed its the driver and not something up the signal chain by swapping channels?


Thank you Eric! 

Yes I have confirmed, I have compneo loaded on another horn body and I can plug it in and sounds fine changing nothing. 

It’s the weirdest thing, it sounds okay, no audible distortion , just definitely missing a little bottom end and the top end is definitely a little louder.


I have looked in the gap as best I can, the neo stack looks in alignment with the top plate that I can see . 

I wonder .......if , this is an aftermarket Diaphram, I changed it out once before and bought the new one from us speaker, thinking I was getting an authentic beyma, but that dosent seem like anything al would do. He’s such a good dood I don’t think he would have even sold me an aftermarket one. 

I just don’t know.... I’m worried I’ll spend 100buck and not fix it. 
Maybe it’s wortnthe extra 50$ to just get a whole new assembly.


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## oabeieo (Feb 22, 2015)

And if anyone’s wondering, I’m not a hammerhead and don’t listen super loud 
It blew last time when I lent them to my buddy and his Rockford 360 liked to completely loose all settings and revert back to default setup on its own with no HPF. 
Mi haven’t blown a compression driver in about 10plus years I would guess, since 2010 at least. But anyway that’s why I had to replace it once. 

When I did swap the Diaphram I played it for about two days and stuck it on the shelf and been sitting for about a year , and now this


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## Eric Stevens (Dec 29, 2007)

oabeieo said:


> Thank you Eric!
> 
> Yes I have confirmed, I have compneo loaded on another horn body and I can plug it in and sounds fine changing nothing.
> 
> ...


compare both diaphragms side by side for any small differences in materials or thickness of parts and windings of voice coils. also you can press lightly on the diapragm and feel for clearance between phase and dome on both as well. y


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## oabeieo (Feb 22, 2015)

Eric Stevens said:


> compare both diaphragms side by side for any small differences in materials or thickness of parts and windings of voice coils. also you can press lightly on the diapragm and feel for clearance between phase and dome on both as well. y



You were right 
No need to compare. It’s smashed up against phasing plug. What the .........
How in the world.  
Other one works fine in this assy. 

No idea how it could happen from just sitting. It has maybe 3 or 4 hours on it. 
But I guess weirder things have happened before. 


New one is on way. 

Thank you BTW.


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## oabeieo (Feb 22, 2015)

GEM592 said:


> A slight change in the geometry, meaning the former is even slightly tweaked, would make it sound wrong. As you know, this could result from running them a little too wide, maybe even with an amp that is a little too small on paper, or just from normal use.
> 
> Maybe swap the diaphrams and check? That's alot of work but it might be definitive.


You called it first man. :wink:


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## oabeieo (Feb 22, 2015)

Lol here’s one for ya and how old I’m getting.


So apparently I already asked this before and completely forgot about it 
So I must have had this problem with this same driver after I even made a thread just like this. So this isn’t the first time. 

It’s entirely possible I had this issue before I packed them. Forgot to repair it and a year later ask the same question and try to solve it again. 
I’m pretty sure at least. 

Either way, I’m glad it’s figured out and I can get it fixed. 
This driver is fun to tinker with for sure it has really good low end midrange, it sounds a lot like the compneo except the compneo is smoother and 1/4th the size and needs way way way less eq. But it’s still a very fun driver to play around with I’m glad I can keep it working now. 

I stuck a bit of masking tape and made a shim , ha it seems to actually work, the added overhang probably isn’t good and it looks like the coil is still all the way in the gap so anyway but it sounds ok now, at least till I can get it properly repaired. Honestly with a tape gasket it seems to sound just fine. And if I blow it up I won’t be sad being it’s already faulty.


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## Helyani (Aug 9, 2019)

How was the problem solved?


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## oabeieo (Feb 22, 2015)

Helyani said:


> How was the problem solved?



New diaphragms. Done 


So the modern polyamide diaphragms can get slightly stretched or warped if they get too hot. This is a completely new issue that I never saw with titanium 

It’s hard to to do you have to hammer on them fairly bad to damage them but it can happen. Especially if your asking the horn to play lower than it can load at full power.


Just because you can get 800hz out of a horn don’t mean you should play it with a lot of power down that low. If the response isn’t there.

Better phase matching to the midrange should allow the lower frequencies on the horn so you don’t need to put near as much power on it at lower frequencies

Meaning, if your horn doesn’t sound like it’s playing very loud under 1k more than likely it’s the mid canceling the output. The horn should play the lower band effortlessly and need fairly large cuts on the eq. It should never be driven hard under 1k.


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