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Measuring driver parameters vs the data sheet values
Measuring driver parameters vs the data sheet values
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Old 11th February 2019, 08:42 AM   #21
wintermute is offline wintermute  Australia
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Measuring driver parameters vs the data sheet values
Oh I think I need more sleep, now I see it. You switched drivers

Can you post the actual impedance plots from the T/S measurement run?

Tony.
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Old 11th February 2019, 08:47 AM   #22
Lojzek is offline Lojzek  Croatia
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Quote:
Originally Posted by ggidzinski View Post
...initial box sizing was way off because the data sheet specs are BS.

George

Now you understand that speaker units are not nuts & bolts, their specs change with climate conditions, age, different materials introduced in production line, etc. You are wasting your time searching for a better way of measuring TSP. I have got Audiomatica Clio, one of the best performing measurement systems in their own time, the 90's of the past century, and I also measure this kind of changes, with Scan Speak, Visaton, Peerless...only Focal and Dynaudio were spot on.
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Old 11th February 2019, 03:17 PM   #23
ggidzinski is offline ggidzinski  United States
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Quote:
Originally Posted by ente View Post
...before going on with your discussion about measurement software /systems have a look at this Klippel paper:

https://www.klippel.de/fileadmin/kli...equency_fs.pdf

Regards
Heinrich
Thank you, this is interesting. Unfortunately it only prolongs the dilemma of figuring out how to determine a box volume for two drivers sitting on my work bench with measured TS parameters that are off by as much as 50% from the data sheet. I still donít know if my measurements are of any value or if I should even be considering doing my own measurements given that I canít spen $5k for this process. Since this thread has enlightened me that measurement condition, order, calculations, etc all affect the result I will restate my earlier question:

Some of you have recommended solutions for raw driver TS parameter measurement like CLIO and Smith & Larson WT2. Do any of these also provide detailed instructions on how to measure to get proper results (proper order, how to do added mass for Vas, warm up driver, etc)? I find for instance that my added mass process is not repeatable so I have little confidence in the results.

Thanks,

George
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Old 11th February 2019, 03:42 PM   #24
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If i remember correctly there is described in the clio standard manual a procedure how to get correct drive level for measurements of driver parameters
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Old 11th February 2019, 04:24 PM   #25
ggidzinski is offline ggidzinski  United States
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Quote:
Originally Posted by wintermute View Post
Oh I think I need more sleep, now I see it. You switched drivers

Can you post the actual impedance plots from the T/S measurement run?

Tony.
Sorry about the confusion. I started pulling drivers to see if I have a consistent problem and I did wind up doing the burn in experiment with a different one.

This is an Aura NS3-193-8A that I bought new that sat around for a few months but was not used. I played music material through it for 24 hours this week to burn it in. Here are the data sheet specs (A), the initial TS measurements with DATS2 (B), and TS measurements after 24 hours of burn in (C). Also attached is the impedance plot of today's 24 hr burn in measurement as well as the data sheet. I did not include Vas because I can't get consistent measurements on this parameter using added weight:

Aura NS3-193-8A:

--------A------B-------C
Re---7.60---7.72---7.77
Fs------80---123----116
Qts---0.67--0.87---0.88
Qes---0.73--1.08---1.06
Qms--8.00---4.49--5.08

Thanks,

George
Attached Files
File Type: pdf Aura NS3--1932-A.pdf (312.4 KB, 18 views)
File Type: pdf 296-258_AuraSound_NS3-193-8A_Specifications (1).pdf (901.3 KB, 3 views)
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Last edited by ggidzinski; 11th February 2019 at 04:29 PM.
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Old 11th February 2019, 04:34 PM   #26
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http://parkaudio.ua/DOCz/knowledgebase/aes02-2012-f.pdf
Chapter 5.4

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Heinrich
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Old 11th February 2019, 04:35 PM   #27
ggidzinski is offline ggidzinski  United States
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Quote:
Originally Posted by planet10 View Post
T/S are curves, not scalars.

Different measuring kit pulls the number from a different part of the curve, so measures can be significantly different. Also whether the sw estimates the parameters or actually measures them. Short of the pro stuff the factories use (ie $5k-ish), Smith+Larson Woofer Tester 2 is probably the best short of them.

I always start with the factory numbers,i have rarely had to redo a box. Also keep in mind that depending on the manufacturer parameters will vary from plus-minus 5% to plus-minus 20& or more.

I use S+L for driver matching and unknown drivers.

dave
Smith & Larson WT2 looks interesting as they claim very good accuracy and repeatability. One thing that I have learned here is that measurement techniques and conditions matter a lot. Do they include good instructions on the process to be able to achieve their claimed results?

Thanks,

George
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Last edited by ggidzinski; 11th February 2019 at 04:39 PM.
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Old 11th February 2019, 04:44 PM   #28
ggidzinski is offline ggidzinski  United States
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Quote:
Originally Posted by ente View Post
Thanks. I suspect that in the case of this small driver that I may have problems with the light added mass weight vibrating under test. In you tube videos guys are measuring giant woofers with water bottles attached to rolls of tape. I have layers of post it notes on mine, measuring them with a sensitive gram scale. Do I need to attach my weight to the surround with double sided tape or something?

Thanks,

George
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Old 11th February 2019, 05:44 PM   #29
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you can use coins for weights

some uses magnets on either side of the cone

some uses clay
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Old 11th February 2019, 05:45 PM   #30
ggidzinski is offline ggidzinski  United States
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do you let the coins sit loose on the cone or do you tape them down?

Thanks,
George
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