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Old 12th April 2009, 04:43 PM   #1
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Default My first Open Baffle Speaker

I owe DIYAUDIO so much.....first the shigaclone, then Peter Daniel's very good DIY amplifier, and now my first DIY speaker.

Used the eminence beta LF 12" and removed the whizzer. Added the Beyma cp380 tweeter crossed at 4 uf series and used a VERY shallow horn.(I also removed the rear plate to allow a kind of dipole configuration, as there was obvious light coming from the front mesh to the rear cap under the metal cover on the rear !) I augmented this with two dipole subwoofers utilising 8" Peerless xls subwofers with the behringer super pro for the low crossover and Quad 606 power amp, (almost certainly inadequate for this will get a Yam p4500 shortly for these duties, and i have also acquired the 12" xxls Peerless subwoofers)).

Having used Avantgarde Duos, Harbeths 30, audio physic avantis, Rogers lS 3/5//8/9, quad esl 57 stacked and recently highly modified YAmaha NS1000's, I am getting very excited by the very musical, open, lifelike size and sounds I am getting. Dynamics both micro and macro are excellent considering there is no box augmentation whatsoever. Timing and rhythm is very good as I am tapping my feet now, initially before burning in it felt like it was a digitilized sound with robotic like singing, but that went after about 24 hrs burn in. The tonal colours are fully apparent and the coherence from top to bottom at my first attempt are very smooth indeed. I am not gonna use any measurements but just my ears!!! Go on have a go. But I am not young and have many many years of experience of listening to hifi.

For what in all honesty including cnc cut birch ply wood frame, amounts to less than 600, this is amazing value for money. Until I do a direct comparison with the Yams I cannot be entirely sure but I have a feeling these must be the best speakers i have ever owned and the list is a good one.

The voices even after 48 hrs burn in were still a little shouty, but after some more reading I added small circular 1cm dia pads around the inner perimeter of the cones and this led to substantial improvement in tonal warmth and lessening of the shoutiness, which I initially suspected was probably due to the tweeter. Only 48 hrs on the speakers and it is improving all the time.

Next will come experimentation with the eminence beta cx and the pro delta 12" drivers, lacquering of the outer perimeter, doubling the mid/bass drivers so as to get 16 ohms etc etc I have not even tried my prize possession yet the Fouriere Panthere OTL's on them, I am just burning in Peter Daniels amplifier. I also need to remember to put the rear cover back on the Beyma's to see if this makes a difference. Of course finally measurement would be interesting though my ears come first. i will look into buying the stuff to do this.

Now where have we heard all this before i wonder???


I read on another thread that these open baffles would murder the so called very high end fancy speakers like the Wilsons etc. out there, but you know what i am beginning to believe that this might just be possibly true.

For those interested I will upload pictures.
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Old 12th April 2009, 05:16 PM   #2
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Almost forgot i wonder what effect the PIEZOBEE would have on the speakers. Must admit they were crap on the DAC but good+ on the Shigaclone and in comparison to the large Bybees I had with me both seemed to have a similar audible effect on the shigaclone dc 9v power supply.
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Old 13th April 2009, 09:31 PM   #3
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I have tonight increased the series cap to the tweeter to 7 uf!! and the midrange has improved dramatically with a more natural tone that has made voices sound so much more real and present. It is getting scarily close to the Quad electrostatics as i remember them!!!

Removing the whizzer aids sound quality??so i have read........ but how much of the high frequency has it knocked off???

6uf would mean a crossover of around 3-3.5k according to one calculation on line.

Do i next increase the frequency response of the woofer by applying violin lacquer to the perimeter?? adding a wooden phase plu?? how wide should the phase plug be??

Appreciate any help anyone can give me.
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Old 14th April 2009, 09:06 PM   #4
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any takers??

No??

not to worry must be my style
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Old 15th April 2009, 12:09 AM   #5
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any pics?

ARTA is a cheap way to take measurements, see thread here,
ARTA

all you need is the software & a mic

re:'applying violin lacquer to the perimeter' - I don't know how predictable this is; I found that applying Dammar to paper cones on 8" stiffened them up, but gave a a peak, similar to ALU cones, but not as strong, and at lower freq, ~1.5Khz - where it's really noticable.

Phase plugs - Planet 10 is the resident expert - maybe ask him on the 'Fullrange' forum?
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Old 15th April 2009, 02:23 AM   #6
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Quote:
Originally posted by audiojoy
Removing the whizzer aids sound quality??so i have read........ but how much of the high frequency has it knocked off???
depends on the whizzer and what else you do to the driver...

Quote:
Do i next increase the frequency response of the woofer by applying violin lacquer to the perimeter?? adding a wooden phase plu?? how wide should the phase plug be??
If anything you increase the stiffness near the voice coil. HF are limited by the size of the voice coil. I wouldn't start modding the driver cone until you have done more research... puzzlekoat on paper cones can lower the cone self-noise, stiffening the whizzer with damar usually helps lift the HF. Drivers with whizzers seem to really benefit from phase plugs. You can also try the 98 cent trick.

dave
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Old 15th April 2009, 02:42 AM   #7
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Hi AudioJoy... where are the pics ?

I'm with Pete, get a simple measurement kit as judging by ears can lead to frustrations (or joy? heh..e).
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Old 15th April 2009, 07:27 AM   #8
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thanks guys for the response much appreciated i will get photos shortly.
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Old 15th April 2009, 07:34 AM   #9
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the spare cut out is for the second equivalent driver to get a 16ohm look in for the amp.
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File Type: jpg my speaker1.jpg (35.9 KB, 4184 views)
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Old 15th April 2009, 08:00 AM   #10
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here is the back using my favourite caps PETP
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File Type: jpg my speaker2 (2).jpg (74.0 KB, 3962 views)
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