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King Tut

Valve Amps and Farting Cabs

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I've recently bought a Peavey VB-2 all valve 225W amp. Through my BF Big Baby II it sounds superb. Over the last couple of days I've been trying it through an Eden EX112 which is a small 12" cab with a whizzer cone instead of a tweeter. With this cab however, when the amp start to break up on the preamp, rather than smooth loveliness, the cab makes a horrible high pitched farty tone. Assuming the driver was fooked, I plugged a Trace SMX AH250 into it. Not so much overdrive on this but the cab sounds just fine. So my question is, is it likely the driver in the Eden is damaged and it's only apparent when overdriven tones are put through it, or is the cab just inherently unsuited to valve type overdrive. Please discuss!

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25 minutes ago, Jus Lukin said:

Do you have the horn on with the BBII?

Yeah tried it with the horn open and shut!

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Quick update. I've taken the cover off the Eden cab. Looking at where the whizzer cone joins the main driver, I can see that the shiny black sealant stuff isn't consistent all the way round. Does this mean the speaker has failed? See pics.

IMG_20201018_115251950.jpg

IMG_20201018_115239711.jpg

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It could well account for the distortion at higher, er, distortion levels!. As far as you can tell, is the whizzer attached ALL the way round, with no air gaps?

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7 hours ago, MoonBassAlpha said:

It could well account for the distortion at higher, er, distortion levels!. As far as you can tell, is the whizzer attached ALL the way round, with no air gaps?

I've got a feeling that the white bits showing in the pic are gaps. It's hard to tell though. I've tried the amp with a 4x10 with tweeter also and it's fine.

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A Big Baby has much higher power handling and much greater excursion. You're probably overdriving the Eden.

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7 hours ago, Dan Dare said:

A Big Baby has much higher power handling and much greater excursion. You're probably overdriving the Eden.

I was wondering if that was the case. It happens at low volume levels though. Or do you mean that through using them together I've damaged the speaker?

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6 hours ago, King Tut said:

I was wondering if that was the case. It happens at low volume levels though. Or do you mean that through using them together I've damaged the speaker?

Probably not if it still sounds OK at moderate levels. It's difficult to damage just the parasitic cone and not the whole thing. It's only a piece of shaped compressed paper pulp stuck to the centre of the main cone, after all. It has no separate motor to drive it, unlike, say, a Tannoy dual concentric unit, which has a complete tweeter mounted in the centre of the main cone that works independently of it. Parasitic cone drivers do have limitations as far as power handling and frequency range are concerned. The parasitic cone is part of and being moved by the main cone, which affects what it does.

Edited by Dan Dare
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This sort of noise might well be due to failure of the adhesives around the cone if this is an older cab. It may well be that the whizzer cone is coming away, also have a look at where the main cone is fixed to the frame and around the corrugated surround. Look at the dust cover, the dome in the middle. I've always used copydex adhesive to glue thins back together. It's latex based and stays flexible and is great with wood pulp things like speaker cones. 

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Whizzer cones are quite unflattering to overdrive tones even if everything is working correctly and you're playing at low volume. I certainly found that with the EA Wizzy 10 I had.

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