Orthodynamic Roundup - Page 185

What we (meaning I and Wualta) fear about the Maior is that it's sound signature is, like the PMB 'phones, so carefully engineered as to make it nigh impossible to change it. Specifically i suspect that the diaphragm in the T50v2 / Maior has a higher self-resonant frequency than the T50v1.

It's a Really Good Headphone. Which is only disappointing if you were expecting a Gobsmacking Great Headphone.

I sometimes balefully consider telling wualta to send me back the Maior. But my problems with that specific Maior are that i can detect buzzing caused by some frequencies of audio, and i'm undecided on how to fix that. It's not a hair in the driver for sure.

Oh yeah, and all SFI 120R drivers that are paid for have been shipped.

Many pairs still available. If you've asked for a quote for overseas shipping, I'll get it to you tonight. Had a busy weekend and a busy monday.

I'll be sending a payment for 2 sets Friday or Saturday.

First, some major disclaimers.

1) This is based on my recollection of what I've read, and my recollection isn't what it used to be!
2) Materials used may be different.
3) Might not even be the same issue.

Bottom line, research and consider before you act.

That said, I recall the Carver 'ribbons' could eventually loosen up to the point they could 'flap' which if I recall correctly often was reported as a 'buzz'.

If I recall, this could be fixed by *carefully* heating the Kapton membrane with a hair drier or heat gun which would shrink the Kapton and thus re-tension it.

As I said. This may or may not be the problem, I may or may not have recalled any part of this incorrectly, and the solution may or may not work based on the materials involved, and even if everything applies, it is still possible to ruin your driver(s).

-john

Believe me, untold hundreds of hours have been spent worrying over it.

Well, on the driver that gives me the most trouble, there's one point on the diaphragm that has a subtle ripple, that when poked with a soft object, makes a crinkling noise. I believe this is the #1 offender.

iirc we believe that the yellowish T50v2 diaphragm is kapton. This is as opposed to the SS-100 diaphragm which is crystal clear and probably mylar or something, yet has the same trace printed on it.

My supposition at this point is that if i apply just enough hot air, the whole diaphragm might not shrinky-dink, but the crinkly ripple - which is crinkly because of the stresses on the material - will de-stress itself and flatten out. Or at least go to some non-crinkly geometry where there isn't a threshold in it's motion where it goes *POP* and snaps the other way.

IIRC, the hair dryer trick was discussed on the 'Bass and DIY Loudspeakers Mailing List' which appears to be long defunct. I'll check my bookshelf as I had kept a 3 ring binder of the Carver content at one point.

It appears that the owners of the Carveraudio web site do repairs of the Carver 'ribbons', and searching their forum, don't seem to suggest the hair dryer. That said, they somewhat have a vested interest in repairing the drivers themselves*.

That said, some repair information might be gleaned from their approach and the discussion in the speaker sub-forum.

There is also occasional talk on the topic on the Planar Speaker Asylum, but a quick search didn't turn up any in depth discussion on the topic.

BTW, how is the Kapton attached?

-john


* Which is not to say it is a bad thing. Looks like when they are done, the driver is as good as new and requires some special skills (dealing with the various tensions, and the mega magnets in these are all daunting tasks for the casual speaker owner).


Edit: Other random links of interest:
Audio X Stream Site Tests of Carver and BG drivers and other interesting stuff.
ACOUSTIC LINE SOURCE RESEARCH - Table of Contents More technical tidbits.

Thanks for the links. The kapton is sandwiched (and glued) between two phenolic rings which are in turn held in place by fiber spacers. iirc.

I found the folder, but there are many hundreds of pages, so not sure if I can find the related material, or if I even saved it.

That said, I had a thought on my way home. You could build a simulated driver and practice the repair.

Buy some Kapton, drill a bunch of holes in a board with a hole-saw, glue the Kapton to the board, let it dry, then 'simulate' the defect by pressing it with an object.

Then, you can practice repairing it. See what works, what doesn't.

-john

I considered that course of action, but you can buy kapton film in a variety of grades - some rated for plenty of shrink, some rated to shrink very little.

Since we don't know what the properties of the original T50v2 film are, i wouldn't necessarily learn anything.

I guess that would explain the much lower sensitivity. I can't wait for some sound impressions (even though I was in the recent batch of shipments and will probably be getting my drivers very soon).

Well I'm halfway through modding my YH-1 and I just realised I might have put the driver in backwards. The other one popped out before I could tell which side was up, the soldered side or the blank side. Now the sound comes out of both sides, so does it make a difference which way it's facing?

Well if they're backwards I can't imagine how good they'll sound put on the right way. The mid veil and darkness are gone and the bass is considerably tighter and more impactful. There's a definite "realness" to the sound, I guess thats down to detail and speed. It would seem that they're a tad harder to drive now, or I'm just listening to them too loud.

Oh, the drivers and materials from ericj arrived today to spur all this on. Now I went with the normal felt, what will super felt change about how these sound? Improvements I'd desire would be even more impact and greater treble extension.

Well, in theory, as long as both are the same, it should sound fine.

But you can't get a good seal with the solder-tab side in front. The big solder tab goes in back. and you really should employ a thin line of some poster tak to seal the driver to the baffle.

The superfelt might be too much. you'll know it's too much when the mids and treble are even sharper but the bass has dropped off.