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-   -   Scan-Speak Discovery woofers ragged FR below 100Hz? (http://www.diyaudio.com/forums/multi-way/194531-scan-speak-discovery-woofers-ragged-fr-below-100hz.html)

Andersonix 12th August 2011 09:56 PM

Scan-Speak Discovery woofers ragged FR below 100Hz?
 
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The four new Discovery woofers at Scan-Speak's site all have ugly response below 100Hz on their FR curves. Is this a "measurement anomaly," and is it even physically possible to have such extreme variations over such a small bass frequency range?

Actually, even the larger Revelator woofers are just as ragged, so what's going on?

Andersonix 12th August 2011 10:09 PM

The data sheets from SS say blah, blah..."it results in very low distortion and a smooth and well behaved frequency response..."

I understand the cone break-up up in the mids, but BELOW 100Hz? FR in datasheets for older SS woofers are much smoother, so have they changed their test method?

Peter M. 12th August 2011 10:20 PM

If you look at the curves of all their woofers, they all seem to have the same peaks at about 25, 40 and 60 hz, even the old ones.

My guess is some kind of measurement anomaly.

Andersonix 15th August 2011 07:11 PM

Indeed Zaph's FR curve for the Scan-Speak 22W/8851T00 looks nothing like Scan-Speak's own curve, so I suppose the smoothing (and other parameters?) is not the same. Now I wonder why SS would want to publicize such relatively ragged curves if it's not a real part of the woofer's response...

pinkmouse 15th August 2011 07:13 PM

Not half as ragged as they'll be once you get them in a real room. :)

speakerdoctor 15th August 2011 07:58 PM

I've been told by one of SS wholesale customers that SS uses state of the art Klipple measuring equipment.
FWIW

adason 15th August 2011 08:28 PM

its quite possible that Scan-Speak measurement has lot less smooting done in comparison to Zaph's measurement, otherwise they do look similar

I have seen similar bumpy response on numerous woofers, I do not think its an artifact. You have to consider Y scale too. Some publish data (like TangBang) practically from 0 dB to 100 dB range for the graph to look better.

dlr 16th August 2011 02:15 PM

Quote:

Originally Posted by Andersonix (Post 2673199)
Indeed Zaph's FR curve for the Scan-Speak 22W/8851T00 looks nothing like Scan-Speak's own curve, so I suppose the smoothing (and other parameters?) is not the same. Now I wonder why SS would want to publicize such relatively ragged curves if it's not a real part of the woofer's response...

The magnitude of those peaks/dips isn't a big problem until below 70Hz, although they appear at around 100Hz. They look like the result of measurement in an anechoic chamber, maybe one designed to be most effective down to around 100Hz. The high Q of the upper range breakup indicates that they're not using any smoothing.

The reason why zaph's curves look better is due to his need to splice a close-mic measurement to a quasi-anechoic measurement due to the limited reflection-free time available for the window of the impulse. His splice is somewhere around 300-500Hz I think, I forget if he provides that detail.

Publicizing these curves isn't an issue for those familiar with the conditions. I'm sure that most of their major customers understand that the response is due to these conditions.

Interesting reading from Meyer Sound here.

Dave

Saturnus 16th August 2011 02:33 PM

Finally a manufacturer publish real and unsmoothed frequency response graphs, and then that's a bad thing?

I give supreme respect to Scan-Speak have the guts to do what no other speaker manufacturer dares.

digits 16th August 2011 03:31 PM

If these are anything like their higher priced lines it will sound phenomenal.
The best speakers I ever heard was a DIY scan speak 3-way, in fact two completely diffirent implimentations built by two friends who did a bulk order. I couldn't choose between them, they were both that good. Especialy the bass, dry and smooth.


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