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Beyma, a Spanish coaxial driver
http://diyaudioprojects.com/Forum/viewtopic.php?f=11&t=4835
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Author:  mwhouston [ 25 Jul 2014, 20:34 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

Cat 5 solid core is used in Xover and wiring inside boxes. I also use it for bi-wire runs from the amp. One wire type and all twisted in pairs from amp to driver. In the last image they are siting on my stereo subwoofers. I called the speakers "VoXConcentric".

Attachment:
VoXConcentric _2.jpg
Attachment:
VoXConcentric _3.jpg

Author:  Gio [ 27 Jul 2014, 10:53 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

Looks good Mark. How do you like the sound. Being separate pieces there is the advantage that you can adjust the alignment of the speakers.

Cheers

Author:  mwhouston [ 27 Jul 2014, 18:30 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

As I posted earlier single driver high efficiency speakers have a sound of their own. Mids and treble good and still playing with bass\treble balance. Works well with all my low power amps.

Author:  mwhouston [ 29 Jul 2014, 07:35 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

I tried to out smart myself my padding down, right from the start, the very efficient dome tweeter in the Bayma. What I discovered tonight is I had suppressed the tweeters far too much. By only dropping the tweeters a few db all the treble and mid range came back.

I had felt the sound a little cardboardy before. But after bring up the tweeters about 4db that "honky" sound has gone. The spin-off is there is a little more volume. About 4db (lol). Treble has lifted.

I also tried my 0.5W UX-171A tube power amp with a newly a Parley (comision job) and the Beymas VoXConcentriC. 98db efficient big drivers worked extremely well with the uP amp. But Parley is the secret that drives the whole system.

Author:  mwhouston [ 07 Aug 2014, 19:32 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

I have replaced the grills on the sub-woofers with 15" and left the top grills 12". It looked unbalanced before. The top grills pop off but the bottom ones stay on. Should be no problem with on low bass coming from the sub-woofers (bottom)
Attachment:
P8072834.JPG

Author:  mwhouston [ 11 Oct 2014, 18:42 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

I'm about to make a new 2-way Xover for the Beymas. This time Xing at 1600hz and a third order Xover on the tweeter section and first on the woofer section. I have now a third order on my smaller 2-ways, VoXDeuX, which I am yet to listen to fully.

Author:  mwhouston [ 10 Nov 2014, 18:51 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

mwhouston wrote:
I'm about to make a new 2-way Xover for the Beymas. This time Xing at 1600hz and a third order Xover on the tweeter section and first on the woofer section. I have now a third order on my smaller 2-ways, VoXDeuX, which I am yet to listen to fully.


I finished the Xover, installed it and had a few listens. I'm not sure this has been a good step. I have read where on the new Zu(s) they use two very efficient large drivers and a tweeter. The tweeter is connected by a single cap. They claim an expensive one. I did look it up and I think about $50 for the cap.

I thought I may go right back to a 1st order Xover and back to a Xing point of 2K. I wound my own choke with heavy gauge enameled copper wire and ferite rod. Two neat layers then a lighter layer proves 1mh. I can trim this back to the 0.56mh I require for a butterworth. The cap is simple just a 4.7uf metalised poly. If I make a Solen split I require a 0.9mh choke and 3.52uf cap (3.3 + .22uf). Here is my hand wound ferite choke.
Attachment:
Choke_1.jpg
Attachment:
Choke_3.jpg


Funny my early electronics as a 12 year old kid was winding electro-magnets. When wounding this I could apply all the tricks I had developed right back then in winding and securing the winding (e.g laying upside down tape toward the .end to then fold back and hold the ends in). I had a little chuckle to myself remembering the hundreds of magnets I wound.

Author:  mwhouston [ 13 Nov 2014, 20:10 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

I decided to follow a butterworth 2K 1st order Xover. For this I only needed a 0.64mH choke and a 4.7uf cap. I like to stay with reasonable quality Xover caps and use a metalised poly. For the 2K Xover I required a 4.7uf cap, a standard size. I measured the caps on my meter and both were spot-on 4.7uf. Very accurate. The caps are rated 250V also.

I took the top layer of wire off my 1mH ferite core choke and this gave me 0.65 -> 0.64mH - more than close enough. I have a 100g 1mm (18BS) diameter enameled copper roll and FYI you could easily make two 1mH chokes. Maybe 3 X 0.64mH. For 0.64mH two tight and close layers on a 4" long ferite rod is all that is required. Resistance of course is extremely low for the choke.

I have hooked the choke and cap up to the Beymas and listening to some spirited jazz. So far so good.

Author:  mwhouston [ 13 Nov 2014, 22:55 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

Well I have now gone full circle and are back with the original Xovers. 2K - Xing, 2nd order on the tweeter and 1st on the woofer. There is still some resonance but the music sounds better on the whole.

Author:  mwhouston [ 23 Dec 2014, 23:28 ]
Post subject:  Re: Beyma, a Spanish coaxial driver

Because one of the Beymas is close to one wall at the TV end of the house the left channel always sounded louder than the right. Toeing the left in hard the the right straight ahead balanced the problem. But then I remembered Gio's tip to toe the Fostex in to focus 1m infront of the listening position. Tried it with the Beymas and now good volume balance and excellent sound stage. Works a treat.

It has changed the whole character of the spekaers. They sound very 3D all of a sudden. Currently the Beymas are powered by my tube and chip amp "Number 9" and Oppo BDP-93 SE.

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