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cbb 27th December 2012 08:33 PM

What did I buy?
 
6 Attachment(s)
I bought some cherry veneered 2-ways a while ago and decided to look under the hood. Not sure if they were a kit. They are 15 7/8" x 9 7/8" x 7 1/8" with 1/2" walls. 6 1/2" woofer labled Eclipse W6518 with 719834 on the magnet. The tweeters say made in Germany 28 8 ohm 95-6383. They had a diffuser on them that I removed. The speakers were ok but had an odd peak in the highs. After I snipped out the plastic in front they were a bit dull. A little boost on the treble control of an older Luxman receiver has them sounding pretty balanced and the peak is gone.

If anyone can tell me anything about them I would appreciate it.

tvrgeek 27th December 2012 08:45 PM

That piece in front of the tweeter is more of a lens, not a diffuser. It has a large effect. Without a lot of work, the "odd peak" is hard to identify. My experience is to look at baffle edge diffraction first. A notch is an easy fix. I see expensive wire, so someone spent a little on them.

mondogenerator 27th December 2012 10:38 PM

+1 There is for example a Visaton metal dome with a similar 'lens'. I once removed one on a Audax 10mm dome tweeter and subsequently wished I hadnt.

phivates 27th December 2012 10:54 PM

I have Magnat tweeters in a Dahlquist with that kind of grid in front of the dome, maybe just for protection. Eclipse as a brand was at one time a Matsushita deal; they paid a local speaker builder to stop using it when they went upscale (slightly) in car audio. Many Euro domes had such a structure in front. We had to remove the grills, remember?
The peak in the highs is probably cone breakup/basket resonance conspiring to make us blame the tweeter.

Dissi 27th December 2012 11:12 PM

The tweeter is a MB Quart MCD 26 titanium dome:

MB Quart 980S MK II - MB Quart 980S MK II Aktiv

cbb 28th December 2012 02:19 PM

2 Attachment(s)
Thank everyone for the replies! I think the builder tried to replicate the Proac Studio 1's. They along with MB Quart and the Avalon Ascent II, which I have heard, used this tweeter. The Avalon unit had a screen mesh with the plastic protection removed. I have also seen a few Proac Studio 1's sold that had the plastic piece removed so I may have done the right thing. The speakers sounded fair before as I had to turn the bass up and the treble way down to be even a bit beareble. Seemed like substandard parts with the crossover saying 'hear I am'. After the removal of the obstruction they became overly mellow. A very slight cut in the bass and the treble at 1:30 has these sounding near amazing. My wife and I have heard a lot of high end gear over decades and these are now worthy of being in our bedroom.

So I dug a bit deeper and unearthed the crossover. Any hints to boasting the highs just enough to be neutral now? I know this is a tough call. Is the 3ohm resistor the key? Not sure if the value should go up or down. Are the crossover parts of low quality? Try not to laugh too hard at my drawing, I am a listener not a builder.

Any ideas about the mid/woofer driver? It seems to sound quite good just would like to know what it is.

By the way I bought these a few years ago off an older gentleman who had them built for his wife to listen to Classical music on. He told me they were of very high quality and a friend that worked at a community college had built them. He said if I did not like them within a few days I could return them. I kept them around to demo equipment and felt the twenty I gave him was fine for that purpose. Now I am thrilled. ;)

chris661 28th December 2012 03:32 PM

The crossover is decent.

I'd say try altering the 5ohm resistor. Get a load of 1ohm resistors (say, 5-10w each), and try different resistances.
I'd guess 3-4ohm to be about right.

Chris

sreten 28th December 2012 07:20 PM

Hi,

As shown the x/o has a coil in series with the bassmid, and a series
capacitor + L-pad on the tweeter, one inductors connection is not
shown but I assume its for the tweeter.

Reducing the 5 ohm will raise treble levels.

rgds, sreten.

cbb 28th December 2012 08:02 PM

1 Attachment(s)
Yes, I tried to revise my post but I could not. I will post the corrected 'diagram'. What is the 3 ohm resistor doing? I have estimated the db's on the tweeter needed to be about 2-3 db up. Does that translate/can it be calulated somewhere to be a change from the 5 ohm resistor value? Such as 1 ohm lower = x db's or are there too many variables?

Anyone want to take a wag at the maker of the mid/woofer driver? Suppose a small change in the resistor will not effect anything else in the crossover.

Is the big blob of Santa's beard all that is needed for the interior? :hohoho:

Thank you for everyones input.

mjf 28th December 2012 09:54 PM

hello.
the 3ohm/5ohm res-combo is a voltage divider.......is like a fixed volume control for the tweeter.
i played around with the simulator.
if you change 5ohm to 4,7ohm and 3ohm to 3,9ohm you should get +1,5db more treble (this shifts the entire frequency response of the tweeter upwards....)


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