100 – 3000Hz, 95+ dB, without peaks?! - diyAudio
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Old 23rd March 2006, 09:34 AM   #1
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Default 100 – 3000Hz, 95+ dB, without peaks?!

There was a mini consensus of “established” thinkers in a local audio club forum, that it’s better to have lower sensitivity drivers and a high powered amp, than vice versa. The idea being higher sensitivity drivers have more ragged response.

I think this is often true, eg a club member has a 95(?) db Focal 6.5 inch that has a pretty unpleasant “shouty” quality, apparently a peak around 1 kHz.
I know from a friend’s experiments that the 100 dB PHL 3451 has a lot of peaks starting around 2.2 kHz, so many that they were not possible to tame with notch filters. I believe the 96 dB Fostex 166 full ranger also has a number of peaks 2- 3 kHz.

I think this is a handy generalization but what are the exceptions?

Eg, I believe the 96-100 dB Aurum Cantus (once ESg) ribbons – yes not cones, and tweeters, are exceptions.

What mid drivers can cover say 100 – say 3000, 95 or more dB, without unwanted peaks (or dips or distortion)?

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Old 23rd March 2006, 05:20 PM   #2
el`Ol is offline el`Ol  Germany
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Is this good enough?

http://www.ciare.com/pdf/catalogo/PM250.pdf
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Old 23rd March 2006, 08:00 PM   #3
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Hi el`Ol

It’s efficient but the graph shows it does have a rising (95 at 200 Hz, 100 db at 1000 – that probably could be filtered) but also apparently a little ragged response . . maybe it just hasn't been smoothed

what does sound like and what does it cost?
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Old 23rd March 2006, 10:20 PM   #4
lndm is offline lndm  Australia
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Combining crossover and carefully tuned shunt notch filters can flatten a peak including the phase anomaly, and IMO can sound very good .
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Old 23rd March 2006, 11:36 PM   #5
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Yes, those techniques can work, but are there any 95 dB mids that don’t need that sort of work?

Cheers
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Old 24th March 2006, 01:12 AM   #6
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Would a wider range than 100 to 3K be ok? The Eminence Beta 8 drivers are very nice. Fast, clean, transparent and 95dB. They do have a rising response above 1K but that is easily flattened with a .4mh choke in series with the driver. The Beta 8 drivers have good response out to 4.5Khz then roll off nicely.

I’m currently using the Beta 8’s in a U-Baffle system. There are 2 drivers per side with one running full range with the .4mh series choke and the second driver running bass reinforcement with a 10mh series choke. The Beta 8’s are covering the 60Hz to 6Khz range. The 6Khz+ range is covered by Hi-Vi Research RT-8 tweeters.

The 20Hz to 60Hz bass duties are covered by a pair of OB subs each having 2 Dayton IB-15 drivers in W frames. The added mass of the air load from the W frames lowers the Fs of the IB-15’s into the 16Hz range. My room supports 20Hz nicely from the OB subs, drops quickly in the 18Hz range but comes back up again in the 16Hz to 14Hz range.

Here is an image of the frequency response measured on one of the early OB test baffles. The dips at 900 and around 2K were caused by the baffle. These don't show up in the current U-Baffle version. There is no crossover other than the .4mh choke. The Beta 8 has a nice natural roll off without out of band peaks.
Beta 8 Frequency response

Here is a current picture of the OB bass, U-Baffle midbass-mids system.
Current system

Gary
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Old 24th March 2006, 04:13 AM   #7
el`Ol is offline el`Ol  Germany
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Quote:
Originally posted by rick57
Hi el`Ol

It’s efficient but the graph shows it does have a rising (95 at 200 Hz, 100 db at 1000 – that probably could be filtered) but also apparently a little ragged response . . maybe it just hasn't been smoothed

what does sound like and what does it cost?

List price is 122 Euro. I`ve seen a kit where it is used BLH, but no reports. The Supravox GMF drivers all have holes.
http://www.supravox.fr
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Old 24th March 2006, 08:52 AM   #8
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A look at the manufacturers’ frequency response graphs shows the Focal (6WM) peaky around 1 kHz, and the Beta 8 peaky around 3 kHz.
Beta 8 Focal
100 93 92
1000 94 97
3000 98 93

I agree the Beta 8 seems much better value than the (now discontinued) 6WM.

Your chokes seems to have worked very well. Though I guess they’re not the answer for a middle of passband problem like the Focal.

Your U-Baffle system is cool! What is (approximate) system efficiency?


If I understand chokes' operation correctly, in shaving off the rising response or peaks, they lower sensitivity to the lowest level in the passband. If the lower XO is 100, the Beta 8 becomes about 93 db, the Focal 92 dB; while the Ciare (which per manufacturers’ graph is > 100 dB at 2.2 kHz) would be more like 95 dB. (And 122 Euro seems quite reasonable)

Cheers
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Old 24th March 2006, 10:35 AM   #9
el`Ol is offline el`Ol  Germany
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I would get them down to 96dB and use an Aurum Cantus G2, which has more reasonable vertical dispersion than the 100dB ribbons.
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Old 24th March 2006, 04:53 PM   #10
ScottG is offline ScottG  United States
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Quote:
Originally posted by Gary P
Would a wider range than 100 to 3K be ok? The Eminence Beta 8 drivers are very nice. Fast, clean, transparent and 95dB. They do have a rising response above 1K but that is easily flattened with a .4mh choke in series with the driver. The Beta 8 drivers have good response out to 4.5Khz then roll off nicely.

I’m currently using the Beta 8’s in a U-Baffle system. There are 2 drivers per side with one running full range with the .4mh series choke and the second driver running bass reinforcement with a 10mh series choke. The Beta 8’s are covering the 60Hz to 6Khz range. The 6Khz+ range is covered by Hi-Vi Research RT-8 tweeters.

The 20Hz to 60Hz bass duties are covered by a pair of OB subs each having 2 Dayton IB-15 drivers in W frames. The added mass of the air load from the W frames lowers the Fs of the IB-15’s into the 16Hz range. My room supports 20Hz nicely from the OB subs, drops quickly in the 18Hz range but comes back up again in the 16Hz to 14Hz range.

Here is an image of the frequency response measured on one of the early OB test baffles. The dips at 900 and around 2K were caused by the baffle. These don't show up in the current U-Baffle version. There is no crossover other than the .4mh choke. The Beta 8 has a nice natural roll off without out of band peaks.
Beta 8 Frequency response

Here is a current picture of the OB bass, U-Baffle midbass-mids system.
Current system

Gary

Looks like someone has been visiting the audio-consulting website.. I wonder if they have been looking at your Tabor?
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