'LGT' Construction Diary - Page 96

ShinOBIWAN · 23rd June 2007, 07:58 PM

Finished modifying the RAAL faceplate to get the look I was wanting. Just need to pad the rear a little so it doesn't sit as deep in the recess.

I'm going to grab some black dye and do the foam deflectors as they just look odd at the moment. Hopefully they'll blend a little better then.

And another baffle trim done

Hartono · 23rd June 2007, 08:02 PM

Cool !!!

MJL21193 · 23rd June 2007, 09:14 PM

Hi Ant,
Very, very good.
The foam is a bit of a waveguide? I thought ribbons didn't have much vertical dispersion?

ShinOBIWAN · 23rd June 2007, 09:27 PM

Quote:

Originally posted by MJL21193
Hi Ant,
Very, very good.
The foam is a bit of a waveguide? I thought ribbons didn't have much vertical dispersion?

The foam broadens the vertical directivity and removes most of the off axis combing in the extreme high frequencies.

RAAL's explanation for the foam:

Also, the wide angle polar response is of great importance for the natural reproduction, therefore using the larger ribbon drivers bares a problem, since they are showing very intensive “beaming” of high frequencies, as they are line sources far bigger than the wavelengths of high frequencies in audible range. For model 140-15D, we found the solution for that problem in using the specially shaped foam pads in front of the ribbon. The dispersion pads are working as an acoustic lens, by slowing down the velocity of sound and thus shaping the sound wave front from cylindrical to spherical. The parasitic effect of partial sound absorption is inevitable, but acceptable. The pads are magnetic and they can slide on the front plate. By adjusting the distance between the pads, sliding them toward or apart each other, it is possible to shape the on-axis linearity vs. wide angle vertical polar response. In this way anyone can adjust the high frequency output by his-hers own liking. If the pads are completely removed, 15 kHz on-axis response is increased in level of about 7 dB.

And a better shot of the driver

augerpro · 23rd June 2007, 10:39 PM

Goodlooking stuff! I cringe just thinking of all the work those enclosures took. I suppose you do to by now

terry j · 24th June 2007, 01:02 AM

lookin good-no scratch that..-great!

You have probably mentioned it earlier, but my mind boggles at re-reading it all again, so forgive me for asking you to repeat it.

The material you have put on the baffles looks fantastic and really is set off against the paint. What is it??, and would it be available in Australia (maybe under a different name I don't know).

Am looking around for nice material to put on my future builds, leather or an acceptable lookalike is high on my list at the moment, but I do like the look of what you are using.

My big problem is when I mount my tweeter, it's the cabasse Dom 40 which (awkward french!) is mounted from the rear, a proverbial PITA. So unlike face mounted drivers I can't cover up any ragged holes by mounting the driver itself, the material has to somehow be securely rolled over into the hole (if that description made sense) and the edge be hidden inside the hole by the driver. Understand??

Do you think that material can be gently eased over into the hole and secured sufficiently to allow the driver to be inserted later?? I hope my description made sense.

Tenson · 24th June 2007, 01:23 PM

Ant,

I doubt you can dye the pads. I tried to bleach some very similar acoustic foam and even neat, it didn't affect the colour one bit. What you might do is cover the pads in a very thin layer of black fabric.

I have some that might do the tick without messing up the sound. It might need 2 or 3 layers but like I said it is very thin and open. If you want me to send you some just email me your address.

ScottG · 24th June 2007, 10:16 PM

Quote:

Originally posted by Tenson
Ant,

I doubt you can dye the pads.

A permanent magic marker (the blackest you can find), should do the trick.

David Gatti · 25th June 2007, 12:19 AM

You may be able to dye them with black ink. Whatever you use, test it on some similar spare foam first as the foam may react to the chemicals.

ShinOBIWAN · 25th June 2007, 12:21 AM

Quote:

Originally posted by David Gatti
You may be able to dye them with black ink. Whatever you use, test it on some similar spare foam first as the foam may react to the chemicals.

Like the fountain pen ink reservoirs you buy from stationary stores?

23rd June 2007, 10:39 PM	#955
augerpro diyAudio Member Join Date: Aug 2006	Goodlooking stuff! I cringe just thinking of all the work those enclosures took. I suppose you do to by now __________________ ~Brandon DriverVault Soma Sonus Old Driver Tests

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23rd June 2007, 07:58 PM	#951
ShinOBIWAN diyAudio Member Join Date: Feb 2004 Location: UK	Finished modifying the RAAL faceplate to get the look I was wanting. Just need to pad the rear a little so it doesn't sit as deep in the recess. I'm going to grab some black dye and do the foam deflectors as they just look odd at the moment. Hopefully they'll blend a little better then. And another baffle trim done

23rd June 2007, 08:02 PM	#952
Hartono diyAudio Member Join Date: Nov 2002 Location: currently in China	Cool !!!

23rd June 2007, 09:14 PM	#953
MJL21193 Account disabled at member's request Join Date: Mar 2007	Hi Ant, Very, very good. The foam is a bit of a waveguide? I thought ribbons didn't have much vertical dispersion?

24th June 2007, 01:02 AM	#956
terry j diyAudio Member Join Date: Aug 2006	lookin good-no scratch that..-great! You have probably mentioned it earlier, but my mind boggles at re-reading it all again, so forgive me for asking you to repeat it. The material you have put on the baffles looks fantastic and really is set off against the paint. What is it??, and would it be available in Australia (maybe under a different name I don't know). Am looking around for nice material to put on my future builds, leather or an acceptable lookalike is high on my list at the moment, but I do like the look of what you are using. My big problem is when I mount my tweeter, it's the cabasse Dom 40 which (awkward french!) is mounted from the rear, a proverbial PITA. So unlike face mounted drivers I can't cover up any ragged holes by mounting the driver itself, the material has to somehow be securely rolled over into the hole (if that description made sense) and the edge be hidden inside the hole by the driver. Understand?? Do you think that material can be gently eased over into the hole and secured sufficiently to allow the driver to be inserted later?? I hope my description made sense.

24th June 2007, 01:23 PM	#957
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	Ant, I doubt you can dye the pads. I tried to bleach some very similar acoustic foam and even neat, it didn't affect the colour one bit. What you might do is cover the pads in a very thin layer of black fabric. I have some that might do the tick without messing up the sound. It might need 2 or 3 layers but like I said it is very thin and open. If you want me to send you some just email me your address.

25th June 2007, 12:19 AM	#959
David Gatti diyAudio Member Join Date: Mar 2004 Location: Melbourne, Australia	You may be able to dye them with black ink. Whatever you use, test it on some similar spare foam first as the foam may react to the chemicals.

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