Good discussion. I had assumed that 'breakup' was areas of the cone kind of 'doing their own thing' and not 100% what the VC is doing. I guess this is a definition of distortion. I was thinking of glueing toothpicks in a radial pattern to try to get all areas of a thin cone to be more pistonic. I am of course hampered by a lack of knowledge in this area, but obsessive compulsive about a cure! I want what y'all want: the smoothness of an 85db Scan-Speak with the efficiency and wide response of a good 8" fullranger.
Edit: I've been using foobar to find the frequencies that sound bad with the Audio Nirvana Super Eight. I suppose it's low tech, but I play a track that's especially annoying to me and then I can use the spectrum to identify the problem frequency and the equalizer to boost or cut the area. So far it seems to be 3khz.
Edit: I've been using foobar to find the frequencies that sound bad with the Audio Nirvana Super Eight. I suppose it's low tech, but I play a track that's especially annoying to me and then I can use the spectrum to identify the problem frequency and the equalizer to boost or cut the area. So far it seems to be 3khz.
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I start with a fairly efficient, 'shouty' ceiling PA drivers and treat them with a thinned varnish to stiffen it up to make it as pistonic as practical, i.e. several very thin coats, use an airbrush for best results), then selectively damp with Dammar or even high solids enamel paint or even rubber cement if a lot is required such as the rim of a whizzer.
I've wondered about superglue in lieu of varnish ever since repairing some compression driver aluminum diaphragms and getting a more robust HF response than less as I assumed would happen when gluing the VCs back on, but have yet to try it.
GM
Using precision scale I have found that a set of 10 toothpicks weighs just ca 1.1-1.2 g
glueing them by means of appropriate glue would result in 5<10% increase of Mms in case of Fostex FE 206E
how would it affect the rest of T-S parameters?
and what about glueing some cork onto the paper cone?
1 cm2 of cork of 2mm thickness weighs ca 0.05 g
glueing three pieces of cork in a three-leaf clover or radioactivity sign pattern that cover ca 1/3 of the cone area would lead to ca 20% increase of Mms (from 15.35 to 18.85)
how would it affect the rest of T-S parameters?
best,
graaf
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oh yes, and actually many times
the guy - Stewart Hegeman - is regarded as one of the most respected engineers in the history of high fidelity industry
interesting interview:
Eico HFS-2 Advertisement
best,
graaf
I haven't figured out a way to keep the VC centered horizontally AND in the proper vertical position simultaneously in order to attach the disks. Suggestions would be welcome.
I've messed up Eminence 15's going overboard w. shellac -might be ok by now after thinner and acetone attempts to dissolve - - -is it considered generally "safe" to do one full coat of violin varnish then a partial diameter (or radioactivity symbol pattern) 2nd coat? - Sammi 8 might be a guinea pig
I would attach the discs (membrane) first to the basket as precise as
possible (using a surround ?).
Then put the driver with the membrane facing on a table top with some
blocks under the basket, so that the face of the membrane is still
reachable.
Then attach the VC to the membrane preliminary using double sided tape
or kneading mass. Shift position until there is no rubbing when moving the
membrane. You can reduce stickyness of double sided tape by fumbling
it with your fingers if needed.
Mark position of VC. Then apply the final glue you want to use,
center VC according to marks. Test for rubbing carefully:
Movement with fingers on center OR battery OR sine wave generator.
Then put spacers under the membrane (without de centering it !)
to make it move slightly inwards to put glue under light pressure.
VC carrier must not touch the membrane directly, glue has to
be between parts everywhere (to avoid singing noise).
Wait and hope ...
You can also use kneading mass (small amount as possible,
best is chewing gum like consistence) to test
the driver to get an impression. Of cause using kneading mass,
there will be some highs absorbed and the moving mass is increased,
but it is sufficient to get an impression of the behaviour of
the membrane.
And if you do not like the membrane you can keep the driver for the
next one to be tried ...
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yes, but isn't breakup in higher frequencies easier to tame? after all the higher the frequency the less energy in musical signal
therefore apart from stiffening which would certainly move the breakup to a higher frequency I propose applying some asymmetrical damping to the cone - eg. with pieces of cork - introducing this differential wave impedance of Ogilvie and Hegeman modifications and of JVC "wood cone"
the idea is to damp the resonance asymmetrically along certain radiuses and in such a way to disperse it
what do You think?
and BTW - would glued toothpicks give more stiffness to the cone then liquid treatments that is dammar and the like?
best,
graaf
I have found something interesting in Gramophone from March 1966, p. 110:
see image attached
also in Gramophone from March 1971, p. 140:
I have done quick search for the patent but so far unsuccesfully.
BTW - Gramophone archives are fantastic! I have just logged in. It's the whole history of high fidelity!
see image attached
also in Gramophone from March 1971, p. 140:
I have done quick search for the patent but so far unsuccesfully.
BTW - Gramophone archives are fantastic! I have just logged in. It's the whole history of high fidelity!
Attachments
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damaging? I would say adapting to specific application. Would You say that Stewart Hegeman was damaging Lowther drivers for His Citation X?
Or would You say that He was allowed to do it because He had a diploma of an engineer and I am not because I haven't?
best,
graaf
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