AudioCircle
Industry Circles => Sonic Craft => Topic started by: OSIB16 on 18 Dec 2018, 06:08 pm
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Hi everyone, I just thought I would document my progress by posting images and info on here regarding my latest Bang & Olufsen classic speaker project. I’m in the middle of modifying multiple pairs of Beovox CX-50 for use in a high end Dolby Atmos 7.1 cinema system. The first picture below is of them before mods are done. Jeff helped advise with the circuit construction...
B E F O R E
(https://www.audiocircle.com/image.php?id=188113)
A F T E R
(https://www.audiocircle.com/image.php?id=232374)
(https://www.audiocircle.com/image.php?id=232375)
(https://www.audiocircle.com/image.php?id=232376)
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The CX-50 uses a bombproof (heavily braced) aluminium cabinet with a thin plastic rear cover.
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SONICAP PLATINUM GEN 1 FILM CAPACITORS (6.8uf)...
(https://www.audiocircle.com/image.php?id=188093)
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Pure Cotton washing line cut into multiple lengths for use as sleeving. Neotech 16awg solid core copper wire for the bass mid drive unit (going to strip off the pvc sleeve). I also used some 6N Jupiter 23 awg copper wire for the tweeter unit which I already had laying around the house...
(https://www.audiocircle.com/image.php?id=188094)
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CIRCUITS BEFORE MODIFICATIONS...
(https://www.audiocircle.com/image.php?id=188114)
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TWEETER HAS AN OBSTRUCTIVE SHIELD COVER (DETRIMENTAL TO PERFORMANCE) WHICH I CUT OFF...
(https://www.audiocircle.com/image.php?id=188115)
(https://www.audiocircle.com/image.php?id=188116)
(https://www.audiocircle.com/image.php?id=188117)
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REPLACEMENT SOLID ALUMINIUM PANELS FOR THE REAR OF CABINETS...
(https://www.audiocircle.com/image.php?id=188118)
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ALL INTERNAL WALLS OF CABINET LINED WITH 4.5MM THICK WOOL (ADHESIVE BACKED)...
(https://www.audiocircle.com/image.php?id=188119)
(https://www.audiocircle.com/image.php?id=188120)
WOODEN BISCUITS GLUED AND SCREWED INTO EACH CORNER. THE REAR SPEAKER PANEL SCREWS ONTO THESE TO SECURE IT TO THE BACK OF THE SPEAKER...
(https://www.audiocircle.com/image.php?id=188170)
(https://www.audiocircle.com/image.php?id=188172)
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MODIFIED CIRCUITS ON NEW REAR PANELS...
(https://www.audiocircle.com/image.php?id=188121)
(https://www.audiocircle.com/image.php?id=188122)
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FITTED REPLACEMENT REAR PANELS...
(https://www.audiocircle.com/image.php?id=188123)
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Thanks for the detailed report . The million dollar question ... How does the refurb sound in comparison to stock ?
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The tweeter cap was to stop bad beaming and make off-axis volume on par.
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Thanks for the detailed report . The million dollar question ... How does the refurb sound in comparison to stock ?
Maplegrovemusic, the stock version has an attactive open sound. Imaging pretty good. Virtually no low bass. Significantly shrill treble. After the modifications the sound becomes “Shockingly Good”. It simply shouldn’t sound this good! Compared to my “SONICCRAFT MODIFIED” Martin Logan CLS IIZ electrostatic speakers; the refurbed CX50 actually produces 90% of the performance (NO WORD OF A LIE!). It does not make sense! The speakers vanish. I’m hearing solid 3D holographic imaging. Super large ‘Soundstage’ producing sounds coming from outside the living room and through the wall. Virtually zero cabinet coloration. Treble shrillness has gone. Thinness has gone. Still no low bass though. The overall sound very much reminds me of the modded CLS IIz. Jeff what the hell is going on? How does a cheap modified speaker like this, sound this realistic and amazing? :scratch: :scratch: :scratch: :lol:
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I’M USING THEM UPSIDE DOWN. PREFER THE SOUND THAT WAY...
(https://www.audiocircle.com/image.php?id=188156)
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REPLACED THE CRAPPY ‘2 DIN’ CONNECTOR SOCKET WITH A SET OF GOLD PLATED SPEAKER BINDING POSTS...
(https://www.audiocircle.com/image.php?id=188159)
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I’M SITTING THE SPEAKERS ON TOP OF “DIY VIBRATION ISOLATORS” THAT I MADE OUT OF OLD PARCEL PACKING MATERIAL...
(https://www.audiocircle.com/image.php?id=188160)
(https://www.audiocircle.com/image.php?id=188161)
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The tweeter cap was to stop bad beaming and make off-axis volume on par.
Folsom, with the cap in place I could hear a slight coloration in the treble region. After removing the cap; the treble opened up and sounded more natural.
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Well, I guess I should check in every once in awhile :oops: I never get update notices after a thread goes awhile... :x
Anyway, your project looks great :D I'm glad to hear it turned out. I would have not removed that phase plug/lens. But, it tends to help more on hard domes, or bright tweeters. If you say it sounds better...you are the ears on the ground :wink: At first when you were referring to it as a cap, I thought you meant capacitor :scratch:
Well done. I'm surprised you used those low copper brass BPs after being so meticulous with the wire. However, I bet they beat what you had.
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Well, I guess I should check in every once in awhile :oops: I never get update notices after a thread goes awhile... :x
Anyway, your project looks great :D I'm glad to hear it turned out. I would have not removed that phase plug/lens. But, it tends to help more on hard domes, or bright tweeters. If you say it sounds better...you are the ears on the ground :wink: At first when you were referring to it as a cap, I thought you meant capacitor :scratch:
Well done. I'm surprised you used those low copper brass BPs after being so meticulous with the wire. However, I bet they beat what you had.
Jeff, advice is appreciated. The tweeters were definitely too bright before I cut off the phase lens. After I did this the treble smoothed significantly. The cabinets are hermetically sealed (more or less); which prevents the problem of the open sleeve copper wires oxidising. How long should I burn in the Sonicaps?
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How long should I burn in the Sonicaps?
I hear improvement up to ~350 hours.
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Can you please share the modified crossover schematic? I have CX50 and would like to upgrade it.
Thanks!
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Can you please share the modified crossover schematic? I have CX50 and would like to upgrade it.
Thanks!
Sorry I didn’t draw a modded schematic. The best I can do for you is provide the following photo shown here...
(https://www.audiocircle.com/image.php?id=212350)
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PURPLE = 18 GAUGE TWEETER
WHITE = 18 GAUGE TWEETER
ORANGE = 16 GAUGE BASS/MID
YELLOW = 16 GAUGE BASS/MID
((ALL SOLID CORE WIRE. NOT STRANDED)))
((DON’T USE THINNER THAN 18 GAUGE WIRE FOR TWEETER, OTHERWISE TREBLE IS TOO BRIGHT))
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Thank you very much for the reply. So the original x-over design for your project remained the same as stock design?
I have some Van Den Hul CS-18 from other project and Jantzen Standard Cap so will tackle it soon. One of my concerns is that silver plated wire will be to bright sounding for tweeter.
I might as well post some pictures after its done.
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Thank you very much for the reply. So the original x-over design for your project remained the same as stock design?
I have some Van Den Hul CS-18 from other project and Jantzen Standard Cap so will tackle it soon. One of my concerns is that silver plated wire will be to bright sounding for tweeter.
I might as well post some pictures after its done.
I have stuck with original circuit board layout. The worst thing you can do is to use silver for the tweeter. As it stands the tweeter suffers with excessive brightness. The best thing is to use 18 Gauge copper (solid core). The fatter you go with copper, the more you can reduce the treble.
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Thanks, will test it with VDH wire and see the result. The issue I am facing is how to solder the wire to tweeter terminal as the factory jack was not intended to be changed. Its quite narrow space for manipulating the soldering iron.
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Thanks, will test it with VDH wire and see the result. The issue I am facing is how to solder the wire to tweeter terminal as the factory jack was not intended to be changed. Its quite narrow space for manipulating the soldering iron.
Just buy some female spade terminals from EBay. Very cheap and do the job. Link below...
https://www.ebay.co.uk/itm/Insulated-Female-Spade-Terminals-Crimp-Connector-Electrical-Terminal-Wiring-Wire/132076481575?hash=item1ec05f2c27:g:aLkAAOSwc1FXYlm~
The other option is to reuse the original spade terminals. Use a thin flat screwdriver and a small pair of pliers to carefully prise them off the existing wires.
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ALL INTERNAL WALLS OF CABINET LINED WITH 4.5MM THICK WOOL (ADHESIVE BACKED)...
(https://www.audiocircle.com/image.php?id=188119)
(https://www.audiocircle.com/image.php?id=188120)
WOODEN BISCUITS GLUED AND SCREWED INTO EACH CORNER. THE REAR SPEAKER PANEL SCREWS ONTO THESE TO SECURE IT TO THE BACK OF THE SPEAKER...
(https://www.audiocircle.com/image.php?id=188170)
(https://www.audiocircle.com/image.php?id=188172)
Jeff, just stumbled across this and it brought back memories as I used to sell these speakers. A couple of comment if I may...
Instead of damaging the cabinets with external screws for your biscuits, I would have recommended exposing an threaded .5-1" hex spacers in each corner which would also allow you to use machine screws. It is not clear that you did this but I would also use a gasket between the back panel and the enclosure. Hope you are enjoying them!
Mark
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They are not mine. Agreed, I'd have done somethings different, but my advice there is not all that helpful post completion :wink:
(OT) Making any headway on those SC3s?
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Sorry, Jeff, I misattributed the post :(. RE:SC-3As, Awaiting on some pick tools.
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Sorry, Jeff, I misattributed the post :(. RE:SC-3As, Awaiting on some pick tools.
Hi Marks, this was my CX-50 speaker, project. Thanks for the tip for attaching the rear metal panels. I’ll bear it in mind for the future. Luckily I only paid approx £50 for the speakers on EBay which is pretty cheap. Anyway; I cut the protruding screws off, and filled any small dents with a decent filler. Then I painted the cabinets. Below is the finished product which works great and are a vast improvement over the originals. By the way I also used a gasket tape equivalent between the rear metal panels and the cabinets, which stops any vibrations.
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(https://www.audiocircle.com/image.php?id=220481)
(https://www.audiocircle.com/image.php?id=220482)
(https://www.audiocircle.com/image.php?id=220483)
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Great write-up. I found this thread searching for upgrade ideas to the CX100's.
I will be following suit on adding billet rear panels to them.
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Wish the early C30's had a simpler x-over design like the 50's. However, got them rebuilt to factory specs/components. They sound excellent. Thanks for the input/advice again.
https://forum.polkaudio.com/discussion/199034/b-o-c30-rebuild#latest