Celestions and cone breakup

[Rhodesplyr]

I've been working on a 1995 Matchless amp with their OEM version of the Celestion Vintage 30 in it, and after some extensive diagnostic tests, we've determined that some annoying harmonics on certain notes are the result of cone cry/breakup. You can actually feel it--and damp it--with your hands. Rather than remaining round, the cone is flexing elliptically. The cone also feels much softer and more flexible than a new speaker I have with the same 444 cone. Being an OEM version, it was undoped, but doping it to try to fix the problem didn't work.

I've owned lots of JBLs and Jensens, but I don't have as much experience with Celestions, so I'm wondering for future reference if this is a typical issue with Celestion cones as they age. The amp's owner reports that this problem has gradually been getting worse, so he finally brought it in to be fixed.

The resolution is that the owner wants a new OEM speaker from Matchless and wants me to recone this one as a spare since he has two of these amps (S/C-30).

[pdf64]

I'm a martyr to cone cry!
My experience is that Celestions (V30, Gold, Greenback, G12H30, G12M25) and likely other speakers with a lightweight cone (eg Jensen P12R) exhibit cone cry if pushed hard with a heavily overdriven power amp, especially when used singly.
The only way I've found to avoid it is to use an array, so as to limit the power to any one speaker.
It may be more effective to put them in parallel, so that they act to damp each other's resonances.
Re-coning, or applying additional dope (within reason) has no benefit.
I've sent a Gold back under warranty and they couldn't find a problem; I suspect their test conditions don't adequately replicate the issue, eg they may be feeding test waveforms via a clean lab amp which maintains a high damping factor.
They reconed it anyway and it was just the same. Applied another layer of their dope around cone edge - no change.
I've reconed V30s using the Celestion kit due to the horrid kazoo noise (before I knew it was called cone cry); again no change.
It's much more prevalent with the heavy / high flux / high efficiency magnet types.
A Weber 12F150 (light dope) was fine under the same conditions but they have a medium size magnet.
Also my Fluxtone (with an Eminence cone) is fine; but a Gold or V30 is noticeably louder than either.
A G12 80 is fine; H magnet but not a lightweight cone.
So, if the aim is to use a vintage type speaker with an overdriven amp, best to limit power per speaker to about 15W.
Pete

[Rhodesplyr]

Thanks, Pete. It almost seems like we should have a Speaker forum on MEF since they have their own issues...

[bob p]

A speaker forum is an interesting idea. I had always thought that speakers were covered OK in the amps section, but I can see why people would be interested in a separate area.

[bob p]

> So, if the aim is to use a vintage type speaker with an overdriven amp, best to limit power per speaker to about 15W.

That's even more true for clean tones!

I did my own speaker shootout several years ago, pitting various celestions like the V30, Greenback and Blues against a handful of Eminence and a few other brands. My experience was that the Celestions always ended up sounding nasty if you pushed them hard enough, the Greenbacks being the first to turn obnoxious in that way. I like your idea to limit power power per speaker to about 15W. In the 2x12 closed back cabinet. I thought that the pair of Greenbacks started behaving badly at about 30W just like you mentioned. The V30 lasted longer. I second your idea on limiting wattage per speaker.

but then this wisdom has been around a while. Leo and Jim created amps with big speaker arrays in the 50s/60s and I remember reading an interview in the 70s where Tom Scholz said that he built his first attenuator for exactly the reasons you mention. He wanted to separate amplifier distortion from speaker distortion, and instead of increasing the size of his speaker array beyond the stack, he just use a brute force method to throttle down the amps to the point that the speakers never started misbehaving.

I think 15W per speaker is spot-on for the low powered speakers like the Greenbacks. Some speakers can handle a bit more, but I think your 15W rule is a good one.

[Steve Conner]

Another data point: I have a Celestion Gold in a 40W 1x12 combo and I've not heard any kazoo noises from it, even cranking it all the way. I think it's a great sounding speaker. I tend to run the bass quite low, though, and I have NFB.

Maybe mine does it too and one man's cone cry is another man's rockin' distortion.

[pdf64]

As it's a combo, assume it's an open back cab?
I can imagine that an infinite baffle might act to keep better control over the cone (but there again I can imagine the opposite too!).
The kazoo only pipes up on certain, heavily overdriven sustained single notes, especially if they're being bent up; maybe it's commenting on my playing?
I've never noticed it with chords or clean/ish tones, though I concur that a Greenback will tend to mush up the 'attack' of the signal envelope.
Pete

[bob p]

Had the Golds been available when I bought my pair of Blues, I probably would have bought the Golds instead.

[Rhodesplyr]

In this case, the owner of the amp is playing loud, but clean, and when he hits the higher of the two C#'s on the B string, the speaker makes a blatty sound. Otherwise, it seems to work fine. I'm able to reproduce the problem with a signal generator on the same frequency, but I had to have him show me the issue twice. I could easily have missed it and thought the speaker had no issues.

The resolution, which was the owner's decision, is to buy a new OEM-branded G12H30 from Matchless, so we'll see if that one performs better...

[Daver]

Matchless, at least at one time, would treat their cones to soften them. That could be the cause of the cone cry. Getting another Matchless speaker may not improve things. The stock Celestion G12H30's I've used never had an issue with cone cry. FWIW.
Dave

[Rhodesplyr]

Matchless, at least at one time, would treat their cones to soften them. That could be the cause of the cone cry. Getting another Matchless speaker may not improve things. The stock Celestion G12H30's I've used never had an issue with cone cry. FWIW.
Dave

Thanks, Dave. I'll check the speaker when it arrives. Since I recone speakers, I have a spare 1777 cone in the shop I can use for comparison. I believe that Matchless is now using a speaker with the stiffer 1777 (75Hz) cone rather than the 444 (55Hz) cone in the V30. In fact, Matchless told me that they don't recommend replacing the speaker in the S/C-30 with the current V30.

[J M Fahey]

Matchless, at least at one time, would treat their cones to soften them. That could be the cause of the cone cry. Getting another Matchless speaker may not improve things. The stock Celestion G12H30's I've used never had an issue with cone cry. FWIW.
Dave

I still remember a Guitar Player article where they did visit the Matchless Factory and "some guys in a back room were pulling Celestion speakers from boxes and wiping their edges with solvent soaked rags".
He didn't understand very well what they were doing, but it's clear for me: those were over the counter or standard Celestions and they were wiping them with acetone to try to pull doping.
A very poor idea by the way, at most you can pull what's outside and little or nothing from what's already absorbed by the paper fibers .
More for looks or mojo than for any useful end.
And working by hand is very inconsistent.

And .... why just don't ask "without"?
Because I guess the minimum order at Celestion for non standard stuff probably runs into 1200 units or something .

While buying standard stuff straight from Factory may involve 6 60 to 120 speakers.