Canít get this Volt woofer to model. - diyAudio
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Old 28th June 2004, 02:31 PM   #1
jonk is offline jonk  Canada
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Default Canít get this Volt woofer to model.

Iím thinking of trying one of the Volt woofers in a new project and was using winISD for modeling. Most Volts seem to model as predicted except for the b2500.1 (ironically the one I was planning on getting). Iíve heard great things about this driver but canít seem to get respectable response. Am I missing something? Hereís the T/S

Fs 25
Qm 1.4
Qe 0.25
Qt .21
Vas 51 L
Xmax 5.5mm
Sd 299 cm2
Le 0.8 mH
Re 5.9
BL 20.3

Iíve search the archives and found praise for this woofer in 70l tuned to 30hz but I doesnít model like that.
TIA for any help.
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Old 28th June 2004, 03:11 PM   #2
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I haven't modelled it because I can tell from experience of modelling similar specs that the low Vas and Qts in a 70 litre box will give a very 'dragged out' response. Ideal alignments will use a box in the range 25-50 litres, I reckon. If you drag the response out by using a large box I think it worsens the transient response and you get slightly sharper roll-off. Overdo it and you get a dip in the response followed by a peaking just before the response plummets.
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Old 28th June 2004, 03:13 PM   #3
sreten is offline sreten  United Kingdom
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You are correct it does not model well in 70L with 30Hz.

IMO anything with box volume > Vas of the driver
there is always a better driver choice out there.

I think you have to realise studio drivers are optimised
for very high levels, so even a 10" would not be used
to go that low as it would run out of excursion.

Volt drivers have a reputation of not being able to
be aligned to go particularly low in the bass, seems
to be another case in point.

sreten.
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Old 29th June 2004, 02:52 PM   #4
jonk is offline jonk  Canada
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Thanks for the response(s).
I just found it strange that many people feel the b2500.1 to be one of the best 10 inch woofers made but it models totally different than any of the other Volt woofers (they model well). I thought the B2500.1 was the woofer used in the rel subs. Obviously eqíed but stillÖ.
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Old 30th June 2004, 12:44 AM   #5
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With 5.5mm of xmax thats going to run out of excursion pretty quick if EQ'd to give good bass flat to 20hz as per sub.... I doubt Rel use this driver.
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Old 30th June 2004, 01:47 AM   #6
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Quote:
Originally posted by jonk
Thanks for the response(s).
I just found it strange that many people feel the b2500.1 to be one of the best 10 inch woofers made but it models totally different than any of the other Volt woofers (they model well). I thought the B2500.1 was the woofer used in the rel subs. Obviously eqíed but stillÖ.
REL dont just use Volt anymore,i am told.
The b2500.1 has a very dry sound quality and its good, but am not one of the people that think its the best, Wilmslow audio may disagree.
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Old 30th June 2004, 03:41 AM   #7
GM is offline GM  United States
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>Iíve heard great things about this driver but canít seem to get respectable response. Am I missing something?

>Iíve search the archives and found praise for this woofer in 70l tuned to 30hz but I doesnít model like that.

====

Looks like a fine EBS to me once the cab is critically damped to flatten the Fb peak. This yields a very 'tight' ~aperiodic alignment of the type best suited for blending to a horn or electrostat, think TL with gain (see sim). Terrible efficiency, but otherwise very nice if it meets the needs of the app.

GM
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File Type: zip volt b2500.1 30hz ebs.zip (71.9 KB, 79 views)
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Old 30th June 2004, 04:53 PM   #8
jonk is offline jonk  Canada
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That is an interesting set of compromises GM. Maybe one I could live with. I would be using this woofer mounted close to the floor, up to ~180hz, crossed over to mangers. I can drive them with a Bryston so power isnít an issue. Plus my room is peaky at 100hz anyway. I was going to use a sealed low q alignment to compensate for room gain.

A few questions (and please forgive my ignorance, I am a beginner) if you donít mind?
By critically damped do you mean keeping the peak at the bottom of the shelf flat?
Iím having a hard time following your sim as far as tuning is concerned.
Whatís the volume of the box?
Are your stuffing the vent?
If I sim it, I tune to 25hz in 30L box but end up with a 20Ē port. How did you arrive at 3Ē port 4 ĹĒ long? Interesting results though. 25 Hz is only 5 db down from 180hz with max spl of 104db (at 25hz!) from 30L.
Maybe Rel did use this driver (well two of them actually).

Paradise ice. Those are some crazy looking drivers on your page.
Thanks all.
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Old 30th June 2004, 05:05 PM   #9
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Quote:
Originally posted by jonk
. I can drive them with a Bryston so power isnít an issue. Plus my room is peaky at 100hz anyway. I was going to use a sealed low q alignment to compensate for room gain.
If I sim it, I tune to 25hz in 30L box but end up with a 20Ē port. How did you arrive at 3Ē port 4 ĹĒ long? Interesting results though. 25 Hz is only 5 db down from 180hz with max spl of 104db (at 25hz!) from 30L.
Maybe Rel did use this driver (well two of them actually).

.
Your no novice if you have Bryston!
I like the Volt but they can be so fussy!
It sounds like your Box design is almost a homage to REL home subwoofers but smaller?
Do you guys like the Mangers in Canada?
Sound like your a pro to me!

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Old 30th June 2004, 08:18 PM   #10
GM is offline GM  United States
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>That is an interesting set of compromises GM. Maybe one I could live with. I would be using this woofer mounted close to the floor, up to ~180hz, crossed over to mangers. I can drive them with a Bryston so power isnít an issue.

====

OK, but the lack of efficiency and sufficient Xmax is, so I recommend using two with twice the Vb/vents/channel.

====

>Plus my room is peaky at 100hz anyway. I was going to use a sealed low q alignment to compensate for room gain.

====

Then EQ will be required to flatten it since either of these rising response alignments will just aggravate the problem.

====

>A few questions (and please forgive my ignorance, I am a beginner) if you donít mind?

====

If I did, I wouldn't be here.

====

>By critically damped do you mean keeping the peak at the bottom of the shelf flat?

====

Correct.

====

>Iím having a hard time following your sim as far as tuning is concerned.
Whatís the volume of the box?

====

Sorry about that, but to model the effects of high aspect ratio cabs required MJK to use internal dimensions instead of net volume (Vb), so net Vb in ft^3 will be the length (L)*SO or SL/1728 since it's a straight tapered (rectangular) cab, or ~2.471ft^3, the referenced 70L.

====

>Are your stuffing the vent?

====

No, the entire cab with 1.0lb/ft^3 of polyfil, though somewhat less is required if acoustic fiberglass is used.

====

>If I sim it, I tune to 25hz in 30L box but end up with a 20Ē port. How did you arrive at 3Ē port 4 ĹĒ long?

====

Small cab tuned low = huge vent required if it's to be driven to its limits with low distortion. Larger cab combined with stuffing dramatically lowers vent mach, allowing a smaller/shorter vent to be used.

====

>Interesting results though. 25 Hz is only 5 db down from 180hz with max spl of 104db (at 25hz!) from 30L.
Maybe Rel did use this driver (well two of them actually).

====

This alignment is what Focal calls a Daline and is very similar to Wayne Parham's Pi Align. Damping the long vents are 'de riguer' for a smooth, well damped wide BW response.

GM
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