Aurum Cantus AC-200MKII 8" what the heck!!

[GOWA]

What the heck is going on with this woofer?
Aurum Cantus AC-200MKII 8"

PE posted these specs:
Specifications: *Power handling: 200 watts RMS/250 watts max *VCdia: 2" *Le: .62 mH *Impedance: 8 ohms *Re: 7.0 ohms *Frequency range: 26-3,500 Hz *Fs: 26 Hz *SPL: 90.0 dB 2.83V/1m *Vas: 2.47 cu. ft. *Qms: 4.41 *Qes: .19 *Qts: .18 *Xmax: 8 mm *Dimensions: A: 8-3/4", B: 7-1/4", C: 3-7/8".

Aurum Cantus gives these specs:


The WT3 gives me the following free air parameters with the driver lightly broke in.
Re = 7.05
Fs = 32.3 Hz
Qts = .4485
Qes = .4764
Qms = 7.667
Le = .8579 mH

Has anyone done proper measurements of this driver? At almost $100.00 a piece, you would think they could do better. Will the real AC-200MKII please come on down!

[speakerdoctor]

Good question GOWA. I bought a pair of their ribbon tweeters (not cheap either) and ended up returing them. They also tested bad.
Don't know what's going on with that outfit. I believe the designs are Euro-based and mfg. is in you-know-where

[badman]

It's a shame that you-know-where has so many who are either incompetent or thieves or both. Lots of fake parts, lots of bad designs, lots of nonsense. It makes the respectable people from you-know-where ashamed. Like the fake space walk.... wth!

Come on, you-know-where, GET WITH THE PROGRAM!

[GOWA]

Here is the Email I sent to PE:
Good day,
Let me start out by saying that I understand that you can't measure every driver you have but it would sure be appreciated if you could do this one. I just measured the Aurum Cantus AC-200MKII woofer with your WT3 and the results are so far off the published specs that I'm puzzled. http://www.parts-express.com/pe/show...number=296-420
The WT3 gives me the following free air parameters with the driver lightly broke in.
Re = 7.05
Fs = 32.3 Hz
Qts = .4485
Qes = .4764
Qms = 7.667
Le = .8579 mH
Is there any possible way you could measure this driver properly? I asked you this question some time ago and was told that it was on your list for testing. I love the way this driver is built and would like to get it in a box with a proper x-over but from listening to the driver and looking at the specs it's hard to know where to start. I just have a feeling that this driver will be a great performer. I think you will be doing all a great service by providing your own measurements. I don't have proper measuring equipment and I've been searching the forums to find measurements but no luck.
Thank you for your time.

Here is the return email from PE:
Hello,

Thanks for contacting us. Actually this driver has been tested by Aurum Cantus and the response plots can be viewed here http://www.aurumcantus.com/aurumcant...AC-200MK2.pdf. If you want I am able to test one of these with the WT3 to check the T/S parameters but I am not personally able to test it with the Clio measurement rig as that is handled by a different department. I hope this helps!
Best regards,

Alex Arnold
Parts Express
Technical Support
800-338-0531 x104


Well, I sent another email to PE and the reply will determine whether or not I will continue as a customer. I bought this driver from PE, not Aurum Cantus. When I first purchased it, I noticed the discrepancy between their posted specs and the Aurum Cantus published specs. So, I contacted PE to let them know of the discrepancy and who ever I was talking to, assured me that the driver was slated to be tested. That was a year ago! I also deal with Madisound where the technical assistance is top notch. I also deal with Solen and CSS where they are sensitive to ones concerns and are genuine. When I contact PE, I always feel like I am being sold not helped.

Last email:
Hi Alex,
Well I think you owe it to your customers to straighten this out. I'm a professional photographer and I can't imagine buying a lens from Nikon that has three different spec sheets. Your posted specs don't match the manufacturer's specs and neither matches the specs given by the measurement tool that you sell. I intend to have a measuring rig set up next summer so I will not have to go through this again. Normally, I don’t buy drivers which don’t have independent testing. I use Usher, Seas, Eton and Morel for most of my work and I was excited to get my hands on a pair of these Aurum Cantus drivers. My hunch was correct. This is a well built driver but from listening tests I think the published specs, spl graphs etc, are way off. I would certainly appreciate it if you could contact the department responsible for measuring drivers to see if this can be done.

Many thanks

[inertial]

Hi ,
these AC have intrigued me too for the hightech cone and huge Xmax.
Do you have measured frequency response? I'm very curious to see one, more than the T/S parameters

Cheers,
Paolo

[GOWA]

Originally posted by inertial
Hi ,
these AC have intrigued me too for the hightech cone and huge Xmax.
Do you have measured frequency response? I'm very curious to see one, more than the T/S parameters

Cheers,
Paolo

The only frequency response chart that I know is the manufacturer's.
http://www.aurumcantus.com/aurumcant..._ac200_mk.html

[SpeakerScott]

Originally posted by GOWA
What the heck is going on with this woofer?
Aurum Cantus AC-200MKII 8"

PE posted these specs:
Specifications: *Power handling: 200 watts RMS/250 watts max *VCdia: 2" *Le: .62 mH *Impedance: 8 ohms *Re: 7.0 ohms *Frequency range: 26-3,500 Hz *Fs: 26 Hz *SPL: 90.0 dB 2.83V/1m *Vas: 2.47 cu. ft. *Qms: 4.41 *Qes: .19 *Qts: .18 *Xmax: 8 mm *Dimensions: A: 8-3/4", B: 7-1/4", C: 3-7/8".

Aurum Cantus gives these specs:


The WT3 gives me the following free air parameters with the driver lightly broke in.
Re = 7.05
Fs = 32.3 Hz
Qts = .4485
Qes = .4764
Qms = 7.667
Le = .8579 mH

Has anyone done proper measurements of this driver? At almost $100.00 a piece, you would think they could do better. Will the real AC-200MKII please come on down!

GOWA,

As a former semi-professional speaker system designer I can certainly sympathize with your TS measurement quandary.

Measurement Stuff:

1. What method did you use to measure the woofers? Added mass or known volume?
2. If you used added mass, how much mass did you add, and how did you add it?
3. How was the woofer oriented facing up or down, or facing forward like in normal use?
4. How was the woofer held in place during measurement? Rigidly fixed or allowed to move?
5. What is the output drive level of the WT3, can you vary it and measure at different levels?

I have found that:

1. Rigidly mounting the driver facing forward.
2. Attaching nickles (5grams thank you US Mint) to the back of the cone with the smallest amount of blue-tak possible.
3. Measuring at a variety of different drive levels...(I use Praxis)

I can get results very close to what manufacturers publish....that said...sometimes drivers do change...and sometimes you do get bad drivers or a bad spec sheet. Your measurements aren't very close...but within the realm of possibility depending on measurement method.

Now for the driver manufacturer...

Sometimes things change...it could be they don't control their process well.

Now for PE....

I've only had excellent support from them. They've taken back drivers that were clearly "off". They can't measure every driver in inventory...

-S

[inertial]

Originally posted by GOWA



The only frequency response chart that I know is the manufacturer's.
http://www.aurumcantus.com/aurumcant..._ac200_mk.html

It is a pity. We need indipendent good measurement like Zaph.
I am perplex, DIYer seems prefer only Dayton these days, and these AC are really beautiful...

Cheers,
Paolo

[GOWA]

It is a pity. We need indipendent good measurement like Zaph.
I am perplex, DIYer seems prefer only Dayton these days, and these AC are really beautiful...

Cheers,
Paolo [/B][/QUOTE]


I couldn't agree with you more. John's contribution to the DIY community is so very valuable.
It would be nice if someone with that kind of talent would pick up the torch. John's recent test of the 18 Sound drivers are a real eye opener to what kind of products are available to the public.

[inertial]

Hi GOWA,

Agreed. Anyway when Zaph have tested the AC 5 1/4 poly , he has commented positively. Good driver. Maybe the frequency respose have a bit more peak than AC's chart, but 90% is ok.
T/S also can vary a lot because CMS is very difficult to respect tollerance.
But normally a bit of compilance shift do not modify enourmusly the
alignment IMO.
Personally I am intrigued by your 200, the 250 and the 170 always with the carbon cone.
We will see............

Cheers,

Paolo