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Old 8th May 2005, 07:28 PM   #1
jemraid is offline jemraid  United Kingdom
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Location: NE Derbyshire
Default TQWT for FR10 ?

I am listening to a pair of SOLO TQWP's with just one Visaton FR10 per cabinet, they sound OK but the cab's were made for some Fostex units, one facing the listener and the other to the rear and firing upwards at 45 degrees.

I noticed a great deal of interest in Berndt Berghard's Cyburg Needle that uses the Visaton FR 8.

I wondered if there was a similar design for the FR 10.

Any help appreciated.

Jim Read
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Old 9th May 2005, 03:23 AM   #2
GM is offline GM  United States
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Greets!

I looked at this driver some time ago for someone and it's a very poor candidate for a MLTL/ML-TQWT due to the tiny Vas, but FWIW this golden ratio BR tuned to ~65Hz sims nice using published specs and has enough gain to maybe not need any BSC:

L = 10.96"
w = 6.78"
d = 4.19"
zdriver = 5.06"
0.75" diameter x 0.75" long vent near/at the bottom

It should work well in an end loaded TL, but the amount of stuffing required to smooth one out tends to 'suck the life' out of a FR driver:

L = 31.448"
So/SL = 21.176"^2
stuffing = 2.108lbs/ft^3 polyfil for an IB response or 1.5lbs/ft^3 for a bit of gain though with what I consider an acceptable amount of 'ripple'

GM
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Old 9th May 2005, 06:16 PM   #3
jemraid is offline jemraid  United Kingdom
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Default RE: VAS FR 10 - FR 8

Thanks for the quick reply GM,

I'm not into the maths thing alas, thats why I asked the question, but the answer goes right over my head.

One thing I did notice is the VAS you mentioned at the start of your post 1.71 Ltr for the FR 10, apparently this is very small.

And yet the Cyburg's Needle uses the FR 8 which has a VAS of 0.67 Ltr, even smaller.

People say it sounds great and there's a whole raft of posts about it.

Confused !!

Jim
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Old 9th May 2005, 06:32 PM   #4
joensd is offline joensd  Germany
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On a search for a low budget fullrange driver I came across the FR10 as well. For a TQWT or the like you should consider the 4Ohm version which has slightly higher Vas (1.9l) and lower Qts (0.566).
I did a sim with the mathcad-sheets with no guarantee :
(BTW: You can download the mathcad explorer and the ported box and TL sheets from http://www.quarter-wave.com/ and play with some numbers yourself)

L=40cm
driver=0.35
S0/SL=2.9*Sd
port radius=1.5cm
port lenght=5.8cm

mathcad numbers assumes inner dimensions and SO/SL is the cross-section area; L the lenght.

Let me know how the speaker turns out (whichever cabinet youŽll choose).
greets
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Old 9th May 2005, 07:22 PM   #5
GM is offline GM  United States
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Default Re: RE: VAS FR 10 - FR 8

Quote:
Originally posted by jemraid
Thanks for the quick reply GM,

I'm not into the maths thing alas, thats why I asked the question, but the answer goes right over my head.

One thing I did notice is the VAS you mentioned at the start of your post 1.71 Ltr for the FR 10, apparently this is very small.

And yet the Cyburg's Needle uses the FR 8 which has a VAS of 0.67 Ltr, even smaller.

People say it sounds great and there's a whole raft of posts about it.

Confused !!

Jim
Greets!

What 'maths'?! All I provided were dims to a simple box and pipe designs.

I didn't do a sim of the other pipe design, you asked about the FR 10. All I know is that of all the various sims I did using well proven design philosophies only yielded the two designs I posted that I would recommend or consider building for myself.

As always though, YMMV.

GM
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