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Chris74 10th January 2009 08:36 PM

Mark Audio Alpair 5/CSS SDX7 DIY
(Link to my ad with pictures from Audiogon)

Mark Audio Alpair 5 suspension-less wideband driver (aka EJ Jordan JX53) paired with CSS SDX7 6.5" Carbon mid woofer in a bass reflex cabinet. This was built in accordance with the plans submitted on Mark Audio's website. The Alpair 5 possesses electrostatic type qualities in transparency and high frequency reproduction, it is housed in a dedication sealed chamber within the cabinet. its overall character is open and fast sounding, a very impressive driver to say the least. Paired with the CSS SDX7 which is a super high quality 6.5" Carbon woven mid-bass driver with fast, punchy bass and superb low frequency capabilities for its size. Crossover components used are Air Foil Alpha Core Goertz inductor, Clarity Cap SA and Duelund resistors. Crossover is 1st order Butterworth and tuned by ear over a period of 4 months for optimum performance. Performance will be unmatched by other similar designs at this price point. Frequency response 30k-40Hz in most rooms and can be powered with modest amplifiers, tube or solid state.

Enclosures are from Parts Express and have several marks on the bottom from spiked stands and Mark Audio drivers have slight cosmetic damage around the outer plastic flanges from drilling and one driver has a tiny tiny dimple on the surface, hence the conservative 6/10 rating. PayPal please add 3.5%. These blemishes in no way affect sonic performance. Please contact me with any questions, thanks. Chris



Creative Sound

ASKING $585 USD o.b.o.

planet10 10th January 2009 10:34 PM

A couple questions (i am playing with these same drivers):

1/ where is the XO? Did you need to pad down the Alpair to match efficiencies. Do you have a link to the construction article (i can't find it on the Mark Audio site)

2/ did you do the easy mod to the SDX7 to cure the "rattle" of the carbon fibre strands? (a must IMHO)


Chris74 11th January 2009 01:56 AM

Hi Dave, the crossover is set at roughly 500Hz using a 10W 2ohm resistor for the Alpair. There is no construction article per se but you can find more detailed contruction pics within the full range forum on this site.

Can you describe to me the easy mod to the SDX7 for the "rattle"? There is no rattle that I can detect in either drivers. Thanks, Chris

planet10 11th January 2009 03:46 AM


Originally posted by Chris74
There is no rattle that I can detect in either drivers.
Get your ear up close to the SDX7 and run your finger and then the back of your fingernail over the cone... hear the ugly noise?


Can you describe to me the easy mod to the SDX7 for the "rattle"?
3 coats thinned puzzlekoat (each successive coat will take less PK. Hold the cone such that you are applyong pPK underneath the voice coil (ie gravity will not cause PK to get into the voice coil gap -- you don't want to glue the voice coil to the phase plug.

Hopefully Bob will be able to get the factory to do this at the factory with subsequent batches of SDX7.


bm815 17th February 2009 02:44 PM

I'm really interested in these speakers...are they still available? If they are please send me an email!

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