Gamma Horn loaded Ribbon VLD-13 - Application Advice Needed - Page 2 - diyAudio
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Old 15th October 2004, 02:58 PM   #11
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Pmik,

Not to worry. I liked that movie, too!

Are these Gamma ribbons out of production now? So little info on them that I got that impression.

Tim
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Old 15th October 2004, 03:58 PM   #12
PMik is offline PMik  United States
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I have come across a Bulgarian site
this site should be the best source for brand new Gamma's since its in the land of origin for Gamma units.
http://www.vissokogovoriteli.plc.bg/home.htm

Like this one original "stripped" VLD-13
http://www.vissokogovoriteli.plc.bg/pics/d/vld40.html

I remember a new Gamma product was released in the mid 80's cant remember its model number
It was a dedicated "super" ribbon-tweeter with integrated 7KHz/18dB crossover, housing was made in solid marble.
The danish "High Fidelity' made a servere testing of it and there verdict was "its full of stars" or somthing like that was said about this unit (hehe).....biggest difference "new feture" was a new larger and better quality of stepdown transformer.
cant remember its price since it was way over my budget , but it didnt come cheap afir.

This is the budget version of the marble tweeter
i believe the performance is close to or equal to the marble version, look at the deepth...shows the large trannie is used in this model.
http://www.vissokogovoriteli.plc.bg/pics/d/vldd80.html

http://www.vissokogovoriteli.plc.bg/p01d.htm
seen in this list...the bulgarians claims less Sensitivity for the VLD-13...as far as i know it should be 94dB...not the showed 84dB
VLD-40 Sensitivity is just like whats my impression of my stripped VLD-12's
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Old 15th October 2004, 06:04 PM   #13
PMik is offline PMik  United States
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And hey!!!

The prices is what i regard as cheap

VLD-13 aprox. US$63.86 ~ 51.59

VLD-40 aprox. US$65.49 ~ 52.91

VLDD-80 not available
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Old 16th October 2004, 12:57 AM   #14
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Default Gamma

Huh? 84 dB is pretty far off from the previous 94 dB. Strange.

You would need to actively crossover with volume control and then use a separate amp for the Gamma highs to get levels right.

90 dB without the horn sounds about right - a common sensitivity for tweeters.

The need to measure the Gamma seems pretty clear. I guess you could still just lash it up and try it.

Prices are pretty good.


Tim
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Old 16th October 2004, 01:20 AM   #15
PMik is offline PMik  United States
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And latest news....the links is for the Gamma factory
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Old 16th October 2004, 01:40 AM   #16
PMik is offline PMik  United States
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Hmmmm....look here my "maggies" had about 87dB SPL 1watt and i used a L-Pad for the Gamma's the scale showed aprox. -1.5dB level to match the MG-II output.
This figure match pretty well with the VLD-40 specs

But now...Im going to mail for specsheets for VLD-13 and VLD-40

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Old 20th October 2004, 07:20 PM   #17
icefox is offline icefox  Hong Kong
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May I know what is L-Pad? Where can I get them? Do I have to DIY it?
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Old 20th October 2004, 07:27 PM   #18
icefox is offline icefox  Hong Kong
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Guys,

To provoke further discussion, I would like to re-post and email I received from another kind soul I meet here in DIY Audio, Sjef. He has shared with me some serious info on the application of the Gamma VDL-1x tweeter.

----
Hi Icefox,

Yes I have these speakers for quite some time now and have a lot of experience with them. They can be filtered very easily because the impedance is nearly totally resistive and because of there extremely lineair frequency response.

There are different models though, mine measure about 12 ohms of
impedance while they are stated as 8 ohm units. See if you have a possibility to measure it's impedance (not with an ohmmmeter, that only measures dc resistance wich is very low)

For a quick use of them you can calculate just simple textbook
crossovers for them (calculated acoording to the real impedance of the tweeter). If you want to do better the only alternativ is to measure them yourself (as always with building speakers)

A couple of tips though. Stay away from 6dB/oct filtering, they just
don't like it. Even when you cross at say 10kHz it's better to use higher order crossovers. In the days I was filtering passivly I ended up using a 5th order butterworth at 3.5 kHz for them (30dB/oct). If you use activ filtering always put a (best quality) capacitor before the tweeters. The DC resistance of the tweeter is very very low and just a little 50Hz hum or DC offset of you amp might kill them instantly. But don't worry, when used properly they are as hard to destroy as any other tweeter.

Another problem is the driver offset. The horn of the tweeter is
rather deep so you have to compensate for that in some way. I compensate it with active delay of the midrange, but if you don't have that possibilty just try to move them a little bit more to the front up until the point it sounds best.

I have read on the forum that you wanted to use them as a super
tweeter with some tannoy's. You can just try that with different value's of capacitors and a L-pad for level attenuation. But even when you cross over at say 16 kHz it works better if you put an inductor in parallel with them (say about 0.5 to 1mH). This way you create a 6dB/oct crossover witch goes steeper into 12dB/oct at lower frequency's.

The cuttoff frequency of the horn is about 1.5kHz and as with all
horn you have to be sure that the tweeter doesn't get any input near that frequency (or at least 20 dB down). That's the point where horns start to shout and that exactly the thing why horns are given such a bad name. That's also one of the reasons a very steep crossover sounds better, I'm using then at 3kHz with a 90dB/oct crossover at the moment.

Feel free to experiment and don't give up. Thes are very good tweeters. I know there are better ones but at this price or even much higher. I like it a lot more than the top range scan speak and seas domes out there, I know because I have them too. But as with all speaker, it's the combination that counts.

With best regards,

Sjef
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Old 20th October 2004, 07:40 PM   #19
icefox is offline icefox  Hong Kong
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Guys,

As I also own the Decca Superweeter box, have had hooked up with Howard Dawson. He provided some great info on protecting the unit by statying away of 6db/octave crossover (I don't know exactly what it means, I assume it's just one capacitor in series of the +ve terminal of the driver unit).

I would like to know if what HD recommended would also apply to the Gamma unit?

Cheers, iCefoX
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Old 20th October 2004, 07:42 PM   #20
icefox is offline icefox  Hong Kong
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Sorry, missed the URL.

http://users.argonet.co.uk/business/...on/fixdst.html
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