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 Post subject: Unusual CSI MDM-TA3
PostPosted: Sat Jun 30, 2012 7:44 pm 
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Location: Winnipeg, MB, CA
Came across these recently and brought them home. Anyone here own a pair? Calibration Standard Instruments model MDM-TA3

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sat Jun 30, 2012 8:07 pm 
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Never heard of 'em but it is pretty obvious based on the driver layout and grandiose(!) name that they were intended for control room monitor use. Too bad that the designer didn't pay any attention to edge diffraction while he was so focused on physical time alignment of the drivers. The sharp edged recess around the tweeter and the nearby big step between the woofer baffle and mid/tweeter baffles are bound to create some pretty nasty comb filtering notches in the high frequencies. Application of some thick felt on the step and in the recess surrounding the tweeter would be a great idea.

Happy Trails!
MTB Vince

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 6:08 am 
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Location: Fisher Branch, MB, CA
Audio Ideas Guide used to sell those little felt ring diffusers that went around the tweeter. They were said to make a difference. I don't see why they wouldn't work around a woofer as well (you may have to make your own).


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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 7:47 am 
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Hi, the pair did have open cell foam across the step and in the tweeter recess but has long since fallen away. The same people behind UREI came up with this company by the looks of things. The drive parts are all handwritten serial numbered.

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 12:57 pm 
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Location: London, ON, CA
How do they sound?

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Ohms

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 1:20 pm 
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How Much is Shipping wrote:
Hi, the pair did have open cell foam across the step and in the tweeter recess but has long since fallen away. The same people behind UREI came up with this company by the looks of things. The drive parts are all handwritten serial numbered.


That makes more sense then. Well thick wool felt like Spica used to use would work better than open cell acoustic foam anyway. The speakers should definitely sound cleaner and image better with the absorbent surround in the tweeter cavity and on the baffle step.

Albert wrote:
Audio Ideas Guide used to sell those little felt ring diffusers that went around the tweeter. They were said to make a difference. I don't see why they wouldn't work around a woofer as well (you may have to make your own).


As the frequency drops, the wavelength gets longer so unless we're talking about the upper end of a mid-woofers pass-band in a two way design like the Spica and Dunlavy designs, the foam or felt surround trick isn't all that useful. BTW, precisely rebating the drivers so the driver flanges sit flush with the front baffle, offsetting the tweeter (and midrange in a 3-way) on the front baffle, and then heavily radiusing the front baffle edges around the tweeter (& midrange driver) will pretty much eliminate diffraction problems too.

Happy Trails!
MTB Vince

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 1:47 pm 
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Yeah, at 1 khz the wavelength would be larger than the driver. I guess the felt tweek works better for higher frequencies like 10 khz, where the wavelength would be a few cm.


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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Sun Jul 01, 2012 7:12 pm 
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AudiOhm wrote:
How do they sound?

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Ohms


Hi, I don't know. The woofers use foam and call for new. It's unsure what I'll do with them. There's someone here in town who has an x-large cro-moly ten speed who's into audio. Perhaps a mutually beneficial trade is in order. I bought them for curiositys' sake. Looking closely at them, thus far, there was some consideration to detail put into these.

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 Post subject: Re: Unusual CSI MDM-TA3
PostPosted: Wed Oct 18, 2017 11:21 am 
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Funny, it's taken me forever (as evidenced by how late to this thread I am) to find another person with a pair of these.

I had a job gutting one of the studios which a major network in NYC used to shoot soap operas, in order to set it up for a newer talk show. I got to take a pair of these home, and I've been using them as my main speakers in my living room since then. Mine also have a strip of black foam along the step, and the same "Hand Calibrated - Serial ########" on the sides.

I also have a pair of their younger brothers, the MDM-TA2s (obtained from the same studio).

I think they sound fantastic - I just haven't been able to find out any info about them (or until now, anyone else who owned a pair) other than that they were hand-calibrated by E.M Long, the owner of the Time-Align patent.


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