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Centre speaker using vintage drivers?

 
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T.O. Chef
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Location: Toronto Canada

PostPosted: Mon May 17, 2010 9:30 pm    Post subject: Centre speaker using vintage drivers? Reply with quote

Wondering if anyone cares to suggest an idea for making a center speaker using Kef drivers to compliment some 105 II's.

I've been using a modern KEF Q-10 with its twin 5.25" bass drivers, 5.25" mid and metal uni-Q tweeter. To date it's the best I can do. I believe all 4 drivers in that box are 4 ohms.
It does spread the dialogue evenly throughout the room, but it can be a bit shrill especially with feminine voices.

I have some B-110's both A and B's, a single T-52, and a single T-27 any of which can be put to use for a center channel speaker.
I suppose if designed correctly with an appropriate crossover & cabinet these drivers could make for a much better timber matched system.

I've tried other solutions such as a pair of Corellis, and a pair of R.101's both running mono but the results were disappointing, beam of focus being too narrow for one thing.

Anyone tried anything homemade for this application?
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proffski
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PostPosted: Tue May 18, 2010 8:26 am    Post subject: Re: Centre speaker using vintage drivers? Reply with quote

Yes, I'll attempt to post picture in due course.
Units used were two 6" Son Audax and four tweeters by the same company.
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T.O. Chef
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PostPosted: Wed May 19, 2010 12:34 am    Post subject: Reply with quote

Thank you Proffski.

That sounds like a BIG center speaker! You are so right though when you commented in a prior post that the center channel in 5.1 / 6.1 / 7.1 set up is a very important part of the HT system. It could be argued it's deserving of more attention than the fronts. +60% of the audio information.
I'd love to see that design of yours.

I was thinking to dissect that Q-10, check the rating of the mid driver and uni-Q tweeter. If they are 8 ohm units, perhaps they can be substituted with a B-110 and a top mounted T-52 .... leaving the twin 4ohm bass units intact.
Of course I can't predict the interaction with the existing X/O, and attenuation may be required on one or both drivers. Could possibly be made to work I suppose .... as long as the sensitivity of the 110 / T-52 is not less than what's in there now. You think?

Perhaps if I reverse engineered the X/O and provided the schematic someone here could advise me on the feasibility of the idea (?)
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proffski
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PostPosted: Wed May 19, 2010 11:19 am    Post subject: Centre Speaker Reply with quote

You are of course quite right, the centre channel is for much more than just dialogue as a lot happens with modern films than just voice information.

The reason for using Son-Audax is because I have had a huge collection I bought of bankrupt stock; my friend being retired spent all he could on KEF drive units for the front main speakers.

Voicing the front to try and match the KEFs I found very difficult, a lot of theory added and then removed!

Before I finalised the design we played around with the placement of the four tweeters for the best sound in that particular room and his and his partner’s favourite sitting position when watching films.
The layout we arrived at looks horribly wrong and in theory probably is but it really works!

I must say that the articulation and presentation of vocals and effects is stunning, transients are sharp without being exaggerated, there is no sibilance considering the cheap tweeters and even the bass is quite respectful.

The total layout I warn you is very unusual and unorthodox, any purists will be shocked, but it had to be in order to win his wife’s approval and permission.
Once I have figured out how to post pictures on here I shall, but be warned and make sure you are sitting down first!!!
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François
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PostPosted: Wed May 19, 2010 1:37 pm    Post subject: Reply with quote

I'm comfortably sit and waiting, because I'm very interested in this too... Same story here : how to compliment 105.2 with a central channel.. I also have some kef drivers B200, B110...
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proffski
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PostPosted: Wed May 19, 2010 9:08 pm    Post subject: Fiends Home Cinema by yours truly. Reply with quote

Ok, I cannot work out as to how I can load images here direct, D'oh! Confused

However here is the link to PhotoBucket, you may have to zoom into the picture in order to see it comfortably.
The KEF CS7 design is exactly as per KEF original except that the mid-rage unit loads into a long progressively damped tube.
THe cabinet is very well braced and damped, consequently it was built deeper in order to keep the internal volume as recommended.
And yes they are on their sides! That was the deal he had to strike with the wife...
The grille is held on with small neodymium magnets, so all that is presented to the room is a nice light neutral grey surface.
The subwoofer is a bit of a monster utilising two 12" units back to back and with electronic equalisation, each driven by seperate 300W amplifiers.

I have promised not to post the picture of the subwoofer till it is fully veneered. (Not my words or choice) Very Happy
Now here is the link: http://s891.photobucket.com/albums/ac114/AndyGoloskof/?action=view&current=TheLot.jpg&jwidget_action=album PLease be patient, slow to load.

The subwoofer is a bit of a monster utilising two 12" units back to back and with electronic equalisation and driven by two 300W amplifiers.

Oh, the KEF bits were bought as 'New Old Stock' and no it was NOT Eprey!
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T.O. Chef
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PostPosted: Wed May 19, 2010 9:59 pm    Post subject: Reply with quote

Brilliant!
I see nothing overly "odd" about that arrangement. I'd LOVE to hear it.
Unfortunately I would be unable to have my L/R so close to the center.
What did the crossover look like? Anything complicated in there to accommodate all those tweeters?
(BTW .... my collection of 4 B-110A's were picked up through ebay from a man who took apart his own home built TL's. He even had the original boxes they came in when purchased.)
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François
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PostPosted: Wed May 19, 2010 11:02 pm    Post subject: Reply with quote

Thanks Proffski. The Cognac with two glasses is a nice touch Wink

So what are these Audax units exactly ?

Quote:
we played around with the placement of the four tweeters for the best sound in that particular room and his and his partner’s favourite sitting position when watching films.
The layout we arrived at looks horribly wrong and in theory probably is but it really works!


May I ask what looks horribly wrong ?
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proffski
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PostPosted: Wed May 19, 2010 11:13 pm    Post subject: Reply with quote

Nothing special about the crossover, I do not remember much but will post details when I find them. Tweeters were wired series / paallel, so they still presented eight ohms.

I had to play around with the crossovers and the tweeter placing until both clients were happy, I got the idea drom a Mission 78C : http://www.audiojournal.co.kr/review/img/mission-78c.gif and http://www.hometheaterhifi.com/volume_8_3/diy-13-audax-center-channel-speaker-9-2001.html

We did try reflex but it just did not sound quite right no matter what configuration we used. Really it is just a bastardised D'Appolito / Mission ripoff which works superbly!

Please note that the units used were not the ones as shown here and neither was the crossover, they were food for thought! http://www.hometheaterhifi.com/volume_8_3/diy-13-audax-center-channel-speaker-9-2001.html

THe software used was by Eminence Designer: http://www.eminencedesigner.com/ which as far as I know is identical to Bass Box Pro http://www.ht-audio.com/pages/BassBoxPro.html
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T.O. Chef
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PostPosted: Fri May 21, 2010 12:39 am    Post subject: Reply with quote

Well Proffski ... I really like the look of the whole set up. If you'd like to offer up the complete CC design with driver versions, X/O map, cab details it seems there's 2 of us here who would be very interested in exploring the feasibility of building it.

Imitation is the sincerest for of flattery, No? And why try to reinvent the wheel ... at least when I know that you know your stuff.

I'm curious to know if your client made use of any rear channel speakers. I use R.101's. Not likely the most ideal match with the 105 II's (T-27's up against T-52's) but mine are necessarily close to the seating, the size is right for the available real estate, and frankly I'm not sure how important it really is to match rear with center & front. Any thoughts on this?
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proffski
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PostPosted: Fri May 21, 2010 8:31 am    Post subject: Obsolete Drivers Reply with quote

Sadly the Audax units were new old stock and obsolete. just as the KEFs which he found and bought locally.
I grabbed a van load of the long discontinued Audax units from Maplin at around a paltry few £ each plus staff discount! Smile

So unless you have access to the original units sadly I cannot help you.
However any other help or advice is free and I'm sure that Colinn and SG (Speaker Guru) would be more than willing as well.

I still have a few tweeters and smaller mid drivers left, I'd be more than happy to pass on at the same price I paid for them + P&P.

The rear and side speakers are all Audax as well albeit somewhat smaller to keep his wife happy. The enclosure obviously was designed for the particular units and adapted for "Domestic Harmony".
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T.O. Chef
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PostPosted: Sat May 22, 2010 12:35 pm    Post subject: Reply with quote

It's encouraging to hear that the Audax tweeters were able integrate well with the T-33's in the CS-7's.

Both Francois and I it seems are looking to find a good match with the R.105's and their T-52's.
Myself, since I have this KEF Q-10 center (with its awful Uni-Q tweeter, mid range & bass that's not too bad), I think the best place to begin is trying a top mounted (T-52B) tweeter. Perhaps even a B-110B to replace the 5.25" mid driver.
IF it's possible to do so.

I'll be sure to post results of this experiment. Meantime ... if anyone else wants to wade in with recommendations / suggestions on the subject I'm "all ears".
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proffski
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PostPosted: Sat May 22, 2010 5:52 pm    Post subject: Reply with quote

The Audax tweeters were a bit aggressive and fizzy; some judicious crude filtering tamed them quite well at the expense of ultimate bandwidth, but at least they ended up singing almost in tune with the KEFs.
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