Dale M7 against Thiersch M7

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
ricardo said:
bockaudio said:
Also, don't measure mics with crossed over multi-speakers. Use one point source.
What would you use today?  In da old days, I used a Tannoy DC but these are silly money in da 21st century.  :(
I've been through the grinder with every Tannoy, for mic measurement,  from the smallest to the largest. What seems like a great idea on paper doesn't work out in the real world. Without the crossover & subsequent EQ, the time delay & huge resonance of the horn make it difficult, even with a digital delay. Bottom line is with measurement, even with modern computers, is that the more errors in the sound source the more errors in the final result.
I have seen single 15" drivers used, as well as uncouples horn drivers.
No one who measures mics for a living uses anything beyond a single driver.
 
bockaudio said:
I've been through the grinder with every Tannoy, for mic measurement,  from the smallest to the largest. What seems like a great idea on paper doesn't work out in the real world. Without the crossover & subsequent EQ, the time delay & huge resonance of the horn make it difficult, even with a digital delay.
Can you please clarify?  "Without the crossover & subsequent EQ" any multi way speaker will be nasty.  But even an old Tannoy DC (with its correct crossover) is reasonable .. at least for comparison measurements against a reference mike.

The main criteria is that the response is smooth and doesn't vary too much with small variation of measuring position.  This millenium I've used an Infinity Primus 150 with some success.  You have to pick your axis carefully.  For the 150 at 1m, its actually the bass unit axis.

What do use for your measurements?

 
Well remember I'm talking about measurements, not mixing. So crossovers are out. You can however, use a delay once you have measured the time difference between the woofer and horn, but both must be fed straight from the amp. This is for either a single sweep or, in case of Bell Lab's SysID, multiple sweeps. I suppose you could segment the sweep into two parts, but then something complicated becomes more complicated. Anyway, the delay is used on the Tannoy to fix the two driver problem. But then you are left with a HUGE peak from the horn, about 15dB IIR. This is why the crossover on the Tannoy is so important, the raw driver is highly resonant. And in measurement, you are already battling room notches (unless you've got the big bucks big chamber) and a 15dB midrange peak is just too much to battle.
I might not disclose all of my measurement stuff, but the driver I use for far field is FLAT from 200Hz-20k. Really. Made in Germany.
For mixing I have ATC, Dynaudios, original JBL lsr28 & 32 (more pretty than sounds good) & the little speaker in my Otari mtr12.
 
bockaudio said:
This is for either a single sweep or, in case of Bell Lab's SysID, multiple sweeps ....  And in measurement, you are already battling room notches (unless you've got the big bucks big chamber)

I might not disclose all of my measurement stuff, but the driver I use for far field is FLAT from 200Hz-20k. Really. Made in Germany.
SysID is a bit lacking this millenium.  You might want to look at Clio.  I recommend it as an inexpensive acoustic measuring system for R&D.  For more money, the latest AP has Prof. Angelo Farina's log sweep (as does Clio) which is the method of choice today.

Less expensive (with free versions) are Angelo's Aurora plugins for Audition & Audacity.  Also ARTA.

All these will do a quasi-anechoic measurement.  By allowing you to window out the room reflections, this allows me to do better measurements in my shed than I could do with big anechoic chamber etc in da old days.

http://www.aes.org/e-lib/browse.cfm?elib=12875 Extending Quasi-Anechoic Measurements to Low Frequencies
(Also the Clio manual which has the best explanation of quasi-anechoic I've seen)

eg. In a normal domestic room with 10' ceiling, I routinely get measurements which are truly 'anechoic' above 200Hz.  With a bit (??) of know how and evil 21st century digits, you can extend the anechoic frequency slightly lower.

For microphones, cos most (all?) reference mikes are omni, you can do good omni measurements to 20Hz.  Cardioids and fig-8s only have pukka info down to the 200Hz limit in a normal room so data below that needs careful interpretation.

BTW, you have similar problems even with a big anechoic.  An anechoic good to 20Hz for pressure measurements is roughly only good to 200Hz for velocity (cardioids & fig-8s)

Single diaphragm mikes have simple behaviour so extrapolating from their behaviour above 200Hz is good.  Alas, you can't do this with double diaphragm capsules.  :(

This is with a cheap Infinity Primus 150 but many other small monitors are good too.

For production testing, there is no contest.  ClioQC has become a de-facto standard in the better Chinese mike & speaker factories.

.. You can however, use a delay once you have measured the time difference between the woofer and horn, ... 
I withdraw my recommendation for using an old Tannoy DC.  The difference in arrivals between horn & cone complicates selection of a window for quasi-anechoic and is not optimal.  Various KEF Uni-Q units are possible but in fact, the small Infinity 2-way was a more repeatable solution.
 
While I genuinely appreciate all that you have laid out in your post, I hope you can see the irony in this statement:
For production testing, there is no contest.  ClioQC has become a de-facto standard in the better Chinese mike & speaker factories.
  :eek:
In other words: that's no endorsement, but I'll take your word for it.
Again, I genuinely appreciate your info, just not the Chinese factory part.
FWIW sysid is our backup software, we primarily use Soundcheck by Listen, as does Shure and Rode.
 
For production testing, there is no contest.  ClioQC has become a de-facto standard in the better Chinese mike & speaker factories
bockaudio said:
In other words: that's no endorsement, but I'll take your word for it.
I suggest there are people / persons in China determined to make the best speakers/mikes/cars etc in the world.  They will probably bemoan the fact that their decadent Western customers simply want the cheapest possible product.

We might call them Akio Morita & Soichiro Honda for convenience.  What's the betting they will achieve their hearts desire within 20 yrs?

If I was making speakers again, I would have them made in certain factories in Sam Chan; not because of price but for quality.

I introduced ClioQC to these factories in the 90's.  Their management was eager to learn how to use it to improve their product.  The Western factories I was dealing with (particularly their management) didn't want to know.
 
Sounds like we've had different experiences in the PRC. But, to the credit of your forward looking statement, I do know of at least <one> builder in PRC who has successfully made  good sounding production capsules, even with improvements.
In re-visiting Clio, in which I was unsuccessful last time I looked about eight years ago, I found the current website to be disorganized at best. Seems like they don't want to sell anything.
But the free links are quite valuable, thanks so much.
Just to clarify, you are using a two way speaker with a crossover for microphone measurements?
 
bockaudio said:
Sounds like we've had different experiences in the PRC.
In all business, you have to know your supplier.  Gold Peak bought KEF & Celestion in the early 90s.  They sent one of their factory managers to the UK to see how to make quality speakers (they already supplied speakers to Philips and some of the better car audio people.  This guy was a caricature of a Chinaman, with thick glasses & buck teeth; always polite & humble.  He spent time in all departments and happily swept the shop floor.  All the other engineers laughed at him and didn't believe me when I said he was probably a king in his own factory.  When I visited his factory, I was astonished at the progress he had made.  Within less than 12mths, his factory was producing better quality than the UK factories.  And yes, it was good to have a king in China who felt he owed you something.  8)

But, to the credit of your forward looking statement, I do know of at least <one> builder in PRC who has successfully made  good sounding production capsules, even with improvements.
Fantastic!  Care to tell use who?

Just to clarify, you are using a two way speaker with a crossover for microphone measurements?
As I said, the most important criteria is "response smooth and doesn't vary too much with small variation of measuring position."

Small 2 way 'monitors' are usually good for this.  There is a small issue with velocity response not being quite pukka cos the units are spaced but I get around this by measuring on bass rather than treble axis to get this right at LF.  At HF, 1m is far enough for 'plane wave' at HF.

The 200Hz 'anechoic' limit is set by the room ceiling height.  All the stuff I'm playing with is single diaphragm so I can make accurate estimates below that even for cardioids & fig-8s.

A small speaker also means your S/N at LF is limited but again, single diaphragms are precisely predictable from data above 200Hz and comparison with an omni reference below that.

David, I see you are a fan of the AKG C12 type capsule.  Calrec's heritage is via Bernhard Weingartner who did C12 for them so we sneer at the Neumann centre terminated rubbish  ;D

I was saddened to see AKG have gone over to the dark side in some of their China made stuff.  :(
 
Mic tester using dc Tannoys here.

Using these only after seeing them used (quite successfully) in production environments. 

Gold-Line TEF (TDS) is used for units under test, also used by Telefunken, Electro-voice, Peluso and others.


 
Certainly speakers and single diaphragm 1/2" mics are a different world than I live in.
David, I see you are a fan of the AKG C12 type capsule.  Calrec's heritage is via Bernhard Weingartner who did C12 for them so we sneer at the Neumann centre terminated rubbish  ;D
I was saddened to see AKG have gone over to the dark side in some of their China made stuff.  :(
Re: center terminated: yes, but, we use both types now.
RE: AKG: I'm not as their change help make room for me. BUT they are still not forgiven for photoshopping  a clearly visible brass CK12 into the headgrille's box photo of the Perception series. :mad:
Fantastic!  Care to tell use who?
(re: Chinese capsules) at least 797.
Mic tester using dc Tannoys here.
Who are you?
I did start out with a TEF system I bought from Keith of KRK back in the day.
using dc Tannoys here. Using these only after seeing them used (quite successfully) in production environments. 
With the time delay compensation?
But, not for R&D, or critical measurement, or yes for those?
I would be surprised if your accuracy did not improve with selection of at least two of the other choices available today for that app.



 

Latest posts

Back
Top