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Old 23rd December 2012, 03:37 PM   #1
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Default Enclosure for very low QTS ?

HI,
Of course, I read the other threads before posting, but I didn't find exactly what I'm looking for. I plan to build enclosures for my new drivers that have a VERY low Qts.

My listening room is 16' x 14 'x 9' and yes, I can place the speakers in the corners. I mostly listening to jazz and classical.

I'm open to any suggestions (BIB, BLH, TQWT, etc.) and I don't really care about the size or the look...

The spec. :
Driver : Audio Nirvana Super 8 Cast Frame
sensit. : 97.3 db
equivalent diaghram radius : 88 mm
equivalent mass : 10.023
magnet weight : 1400 g
net weight : 3690 g
Fs : 44.63
Re : 7.2
Mms : 11.748 g
BL : 11.84 TM
Qts : 0.162
Qms : 3.836
Qes : 0.169
Vas : 66.495 ltre
Xmax : 1.0 mm
no : 3.379 %

Thanks a lot !
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Old 23rd December 2012, 03:54 PM   #2
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with such low Qts and not small Bl - backloaded horn should be considered.
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Old 23rd December 2012, 03:58 PM   #3
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Quote:
Originally Posted by Charcoal View Post
with such low Qts and not small Bl - backloaded horn should be considered.
Thanks for your reply. If I go with BLH, do you have some particular suggestions?
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Old 23rd December 2012, 04:12 PM   #4
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I'd 2nd the use of a back-horn for this unit, but you'll need some help from the amplifier (viz. a reasonably high output impedance), or Eq of xyz kind, be it passive, active, or high resistance speaker wire, since if the advertised spec. is correct, the driver's -3dB mass corner will be at 528.16Hz -higher than any back-load can be practically run.
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Old 23rd December 2012, 05:00 PM   #5
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Quote:
Originally Posted by spartiate1952 View Post
HI,
Of course, I read the other threads before posting, but I didn't find exactly what I'm looking for. I plan to build enclosures for my new drivers that have a VERY low Qts.

My listening room is 16' x 14 'x 9' and yes, I can place the speakers in the corners. I mostly listening to jazz and classical.

I'm open to any suggestions (BIB, BLH, TQWT, etc.) and I don't really care about the size or the look...

The spec. :
Driver : Audio Nirvana Super 8 Cast Frame
sensit. : 97.3 db
equivalent diaghram radius : 88 mm
equivalent mass : 10.023
magnet weight : 1400 g
net weight : 3690 g
Fs : 44.63
Re : 7.2
Mms : 11.748 g
BL : 11.84 TM
Qts : 0.162
Qms : 3.836
Qes : 0.169
Vas : 66.495 ltre
Xmax : 1.0 mm
no : 3.379 %

Thanks a lot !
measure your t/s specs exactly for your units first and make sure you're actually dealing with those specs first!

Measuring Frequency Response Using ARTA
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Old 23rd December 2012, 05:02 PM   #6
kevinkr is offline kevinkr  United States
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Screams Onken box to me.. I'm running Onkens with low qts drivers - namely the Iconic 165-8G which is essentially similar to the GPA 515-8G or late Altec 515..

Xmax seems very limited which IMO would mean that you should not be going for the ultimate in bass extension with these drivers and should probably cross to something else around 100Hz or so. Certainly would measure the TS params as suggested in a previous post, and probably try a simulation in a tool that will give you your xmax limitations..
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Old 23rd December 2012, 05:10 PM   #7
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Quote:
Originally Posted by Scottmoose View Post
I'd 2nd the use of a back-horn for this unit, but you'll need some help from the amplifier (viz. a reasonably high output impedance), or Eq of xyz kind, be it passive, active, or high resistance speaker wire, since if the advertised spec. is correct, the driver's -3dB mass corner will be at 528.16Hz -higher than any back-load can be practically run.
Thanks Scott for those useful informations. I already start to take a look at some BLH design, but it meens a lot of wood working. I would have more time to realize this kind of project in 1 or 2 mounts. Till this moment, I would like to do something more simple. I talk to a guy who made BIB enclosure to use with a pair of AN super 8 (regular, not cast frame). He did it 5 years ago, was very satisfied, but for some reasons, didn't keep them. Here the thread :

giant BIB audio nirvana super 8

He also told me that you gave him some advices and measures. I'm not asking you to do the job for me , but I would be very happy to have your opinion. Do you think it worts it do the experiment of using AN in BIB? I already made some calculations with the BIB Spreadsheet from Zillaspeak and it gave me some bizarre results (not sure to use this tool correctly) : Suggested Dimensions : Depth=12.51, Width=8.84 and Height=75.42

Thank you very much and sorry for my awful English. It would much better in French...
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Old 23rd December 2012, 05:12 PM   #8
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You'll need some series resistance, but you could use a ported box.

Throw the parameters at WinISD.

You can use 20-40L, tuned between 60 and 40Hz respectively, with 5-8ohm series resistance (the option to add resistance is in the "signal" tab).

You'll lose some power in the resistor, but given the high sensitivity of the driver, I don't expect that to be a big problem.

Chris
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Old 23rd December 2012, 05:19 PM   #9
sreten is offline sreten  United Kingdom
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Hi,

A driver screaming for a variable output impedance amplifier IMO.
See Elliot Sound Products for how to DIY one (feedback mod).

rgds, sreten.
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Old 23rd December 2012, 05:54 PM   #10
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thanks everyone!

I guess ported box would work, but I already use this type of enclosure with my Tannoy HPD315 and I'd like to experiment something new for me. About the resistance, You're right AN are sensitive, but my amp is not very powerful, it's a SET tube 45 type 1,72 w.
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