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Multi-Way Conventional loudspeakers with crossovers

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Old 9th February 2018, 02:23 PM   #2421
lowmass is offline lowmass  United States
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sooo I would like to hear more on the low Q high Q thang.

I have an OB planned in future as a test bed for a ribbon design. The ribbon is 88 db sens and is used down to 200 hz. I would like to stay with one woofer (ribbon mounted above woofer NOT to side) and keep the overall baffle no more than about 35-38 inches tall)

So heres my question,I would like to not have to pad the ribbon down and my calcs say I need approximately 10-12 db more sens on woofer to get the correct FR down to about 40hz. That means a 98-100db woofer.

From what I see there are no 98-100 db woofers with a high Q. The Eminance Alpha 15 A is a high Q but its about 3 db shy of desired sens.

So the question is this. are the high Q woofers really OK in OB setup to get to 40 hz or is the high Q going to roll the lows off to quickly?
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Old 9th February 2018, 03:08 PM   #2422
heinz1964 is offline heinz1964  Denmark
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Default Not 100 dB

Hi

I think the sensitivity that is in a datasheet of most of the woofers I know of is measured at ore above 100 Hz.

At 40 Hz there is a lot less sensitivity.

Uwe
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Old 9th February 2018, 03:18 PM   #2423
lowmass is offline lowmass  United States
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Quote:
Originally Posted by heinz1964 View Post
Hi

I think the sensitivity that is in a datasheet of most of the woofers I know of is measured at ore above 100 Hz.

At 40 Hz there is a lot less sensitivity.

Uwe
Ok but isnt that FR a result of the baffle they use in those measurements??
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Old 9th February 2018, 05:59 PM   #2424
rjbv17 is offline rjbv17  Portugal
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Quote:
Originally Posted by lowmass View Post
...

So the question is this. are the high Q woofers really OK in OB setup to get to 40 hz or is the high Q going to roll the lows off to quickly?
See this: Open Baffle woofer what is important?

You will not reach a conclusion, I warn you.

And see the projects of Troels Gravesen with low Q woofers here: DIY Loudspeaker Projects Troels Gravesen

After about 6 years using the Alpha-15A in my narrow baffle OB project (with Fostex Fe206En FR), with only a 1st order low pass (800 Hz) for the woofer, I decided to try a low Q high sensitivity woofer (Faital 15PR400). Still waiting for it because it is sold out here in Europe.

In my small room and with a 300b SET amp (6 W), the Alphas, although pleasant, are a bit shy (I'm not bass dependent).
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Old 13th February 2018, 01:15 PM   #2425
lowmass is offline lowmass  United States
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Originally Posted by rjbv17 View Post
See this: Open Baffle woofer what is important?

You will not reach a conclusion, I warn you.

And see the projects of Troels Gravesen with low Q woofers here: DIY Loudspeaker Projects Troels Gravesen

After about 6 years using the Alpha-15A in my narrow baffle OB project (with Fostex Fe206En FR), with only a 1st order low pass (800 Hz) for the woofer, I decided to try a low Q high sensitivity woofer (Faital 15PR400). Still waiting for it because it is sold out here in Europe.

In my small room and with a 300b SET amp (6 W), the Alphas, although pleasant, are a bit shy (I'm not bass dependent).
I look forward to your report on the difference
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Old 13th February 2018, 06:12 PM   #2426
MITsound is offline MITsound  Canada
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Quote:
Originally Posted by lowmass View Post
I look forward to your report on the difference

Me, too. I went to Onkens with dual 15" each, to get some wallop out of a 300B set.
Far nicer bass than a sub woofer.

They have 511B horns in again, but I'll be trying either 12P or 12PW open baffles augmented by these soon.
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Old 13th February 2018, 06:29 PM   #2427
mkane77g is offline mkane77g  United States
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The Eminence Beta 15A works well for $79. Eminence Beta-15A 15" Driver
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Old 15th February 2018, 01:37 PM   #2428
lowmass is offline lowmass  United States
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Originally Posted by mkane77g View Post
The Eminence Beta 15A works well for $79. Eminence Beta-15A 15" Driver

can you give details? design, crossover point etc...
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Old 15th February 2018, 02:04 PM   #2429
stijn001 is offline stijn001  Netherlands
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Quote:
Originally Posted by lowmass View Post
can you give details? design, crossover point etc...
I recently replaced a Eminence Kappa 15LFA with a Faital 15PR400. On paper they look very similair. But it was a really good sound improving upgrade, the Faital goes about 5Hz deeper and augments the mid/low with more of a throaty presents. I like it a lot.

It's filtered low pass/second order with 12mH and 100Uf. I estimate overall system efficiency around 97dB

Click the image to open in full size.

Last edited by stijn001; 15th February 2018 at 02:06 PM.
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Old 15th February 2018, 03:03 PM   #2430
mkane77g is offline mkane77g  United States
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Active crossover 4th order BW low pass.
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File Type: gif OB SPKR (1).gif (78.6 KB, 155 views)
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