Possible use of a very low QTS driver?

giralfino · 10th January 2011, 09:59 AM

Hi all,

I have a TB W4-656 midbass driver. According to the datasheet it should have a Qts of 0,33. I measured instead a value of 0,16.

Apart from the annoying discrepancy, what is the best enclosure for such a low Qts?

TIA, Ralf

richie00boy · 10th January 2011, 11:11 AM

That seems very low, maybe you need to check your method was correct. If it is that low, you would have to use a ported box.

phase_accurate · 10th January 2011, 01:29 PM

Such a driver would be suitable for a horn, but I do also suspect a measurement error.

Regards

Charles

Cal Weldon · 10th January 2011, 01:39 PM

First time a Tang Band, (or most any driver) measured lower than spec'd?

giralfino · 10th January 2011, 02:43 PM

I used the added mass method on Limp with this jig: ARTA Jig
Only need to run a sweep, measure driver diameter and DC resistance (on a ohmmeter across terminals). What could I have done wrong?

I suspect that the driver is NOS, and probably sat unused in a warehouse for some years. Could this be the problem?

Ralf

a.wayne · 10th January 2011, 02:58 PM

Manufacturers Qts specs are usually lower than actually measurements, never seen it the other way hevar .

Vented box for sure ...

richie00boy · 10th January 2011, 04:05 PM

Quote:

Originally Posted by giralfino

I used the added mass method on Limp with this jig: ARTA Jig
Only need to run a sweep, measure driver diameter and DC resistance (on a ohmmeter across terminals). What could I have done wrong?

I suspect that the driver is NOS, and probably sat unused in a warehouse for some years. Could this be the problem?

Ralf

The mass needs to be accurately known and change Fs by approx 50 percent. You need to include a third of the surround in the cone diameter measurement. Did you take a baseline DC resistance reading to account for lead resistance?

So potential for a lot of errors really!

godfrey · 10th January 2011, 04:12 PM

How do the rest of your calculated values compare to the specs? e.g. Moving mass, compliance and resonant frequency.

10th January 2011, 09:59 AM	#1
giralfino diyAudio Member Join Date: Feb 2009	Possible use of a very low QTS driver? Hi all, I have a TB W4-656 midbass driver. According to the datasheet it should have a Qts of 0,33. I measured instead a value of 0,16. Apart from the annoying discrepancy, what is the best enclosure for such a low Qts? TIA, Ralf

10th January 2011, 11:11 AM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	That seems very low, maybe you need to check your method was correct. If it is that low, you would have to use a ported box. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

10th January 2011, 01:39 PM	#4
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	First time a Tang Band, (or most any driver) measured lower than spec'd? __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
what sounds best . . . Low Qts in small cab or higher Qts in bigger cab	mikelm	Subwoofers	18	15th July 2009 10:46 AM
What Is The Problem With Low Qts Drivers in QWTLs?	CarlosT	Subwoofers	7	1st April 2008 03:07 PM
Long voicecoil, low Qts drivers	TwangBar	Multi-Way	0	12th October 2006 12:47 AM
Need 8" sub - low Qts, low Fs???	geolemon	Subwoofers	14	19th June 2005 12:38 AM
Low Qts woofer	bigwill	Subwoofers	19	15th March 2005 07:45 PM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

10th January 2011, 01:29 PM	#3
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	Such a driver would be suitable for a horn, but I do also suspect a measurement error. Regards Charles

10th January 2011, 02:43 PM	#5
giralfino diyAudio Member Join Date: Feb 2009	I used the added mass method on Limp with this jig: ARTA Jig Only need to run a sweep, measure driver diameter and DC resistance (on a ohmmeter across terminals). What could I have done wrong? I suspect that the driver is NOS, and probably sat unused in a warehouse for some years. Could this be the problem? Ralf

10th January 2011, 02:58 PM	#6
a.wayne diyAudio Member Join Date: May 2008 Location: Front Row Center	Manufacturers Qts specs are usually lower than actually measurements, never seen it the other way hevar . Vented box for sure ...

10th January 2011, 04:12 PM	#8
godfrey diyAudio Member Join Date: Nov 2009 Location: Cape Town	How do the rest of your calculated values compare to the specs? e.g. Moving mass, compliance and resonant frequency.

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read