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Issue with ProAc D40 speaker - any suggestions to resolve the issue

Hi,


I recently bought used ProAc D40R couple of months back, and driving them with Bluenode streamer —> Digital Audio company Marachino Class D Mono blocks.


After a month or so I realized that absence of the sound from one of the ribbon tweeter, showed it to local audio equipment dealer, they fixed the issue (it was loose tweeter harness wire), now I get the sound from both the tweeter.


Recently i compared these speakers against my exiting DIY Audio Nirvana 8” Alnico single driver speaker using ‘Spanish Harlem’ Track by Rebecca Pidgeon, to my surprise Audio Nirvana sounded more clear and I can hear all the details especially shakers in the left back corner and all other details while on ProAc D40r I can barely hear all those tiny details in the background to me that should not happen with ProAc being such great speaker especially with Ribbon tweeter, so just wondering What could be the issue, Can it be a Crossover Caps issue (as the person I bought these from mentioned those were in storage for almost a year and I read it somewhere here on audiogon thread that caps in crossover may go bad if you store it for long time). 

Really appreciate any recommendations/remedies to resolve the issue, eventually i will have take it back to audio dealer but just wanted to check on forum that if anyone else experiences this kind of issue and what was the solution.


Thank you,



listener111

Showing 3 responses by motokokusanagi

motokokusanagi
189 posts
 
If there is a defect (hard to know without doing a frequency sweep and using proper measurement equipment), it may be a crossover component, wiring fault, or faulty driver. Caps are unlikely to just fail after being in storage for 1 year, but that doesn’t mean there isn’t a fault somewhere.

In the meantime, perhaps do some basic testing with a microphone app. Level match the amp volume to the speaker outputs at a given frequency using a test tone (e.g. 261hz, middle C), then compare the volume levels at different frequencies. Ensure also the volume levels match between the individual left and right Proacs.

Not sure what frequencies shakers are at; going off of hi-hats and cymbals, have your testing include the 2khz-3khz range, and up from there, if we're suspecting there's an issue with treble reproduction. 
motokokusanagi
189 posts
 
@rcprince might be right. @listener111 mentioned previous diagnosis said tweeter wiring was loose. IIRC, Proac crossovers generally have the tweeters connected in reverse polarity. They’re probably attached using quick connects, so if you felt up to it, carefully unscrew and remove the tweeters and check the wiring and connections are consistent both left and right. If one is not wired the same as the other, rewire it so that both are the same and see if that fixes it. It might be wired after the last "fix" so that they’re now out of phase and cancelling each other out left and right.

Levels discrepancies from 2-3khz and above would occur if that is what’s happening if you still wanted to test that way.

Hopefully Proac’s internal wiring cable distinguishes positive (e.g. red) and negative (e.g. black) legs. If reverse polarity, then the black (negative cable) would be going to the positive tweeter terminal (usually marked with a red dot)

Otherwise, http://www.troelsgravesen.dk/polarity.htm
motokokusanagi
189 posts
 
Sure thing. The crossover frequency should be between 2-4khz. You can verify any gross discrepancies in volume output using your phone, using the old speakers as a control, then the left and right Proacs, and both together. Find some percussive music also and do a sanity check if you find a discrepancy using just test tones. If you find a drop in volume output between the individual speakers of -3db or more, then there's a fault.

Subsequent fault diagnosis would require removing the drivers and crossovers.
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