Compression Driver as Midrange Dome?

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Tenson

Member
Joined 2006
audiosmile.co.uk
Hi all,

I was browsing for 3" (75mm) midrange domes with an idea for a new project.

However I found that two of the best are no longer available! The ATC and the TangBand :(

How possible is it to use a good compression driver as a midrange dome? I'm sure I've heard of people doing this.

I've got absolutely no experience with compression drivers. Would one remove the back cup to access the dome side, or what?

The drivers from BMS and Radian look like very well engineered items.

Yeah I know about the Volt driver and the ScanSpeak / Vifa D75MX
 
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JMFahey

JMFahey

Member
Joined 2009
First you whould need to remove the compression chamber to expose the dome, but I guess main problem will be compression drivers are designed with VERY SHORT excursion in mind, because that´s how *compression* works, inside a TIGHT chamber.

Not so sure about them pushing free open air.
 
T

Tenson

Member
Joined 2006
audiosmile.co.uk
Audio Elite said:
Why dont you go for the Volt, its almost identical to the ATC and certainly leagues better than the Tangband!
Click to expand...

From the data I've seen that is not the case.

The Volt is pretty average looking in terms of HD (about 0.4% at 94dB) - Test Bench: Volt Loudspeakers VM752 3” Midrange Dome Driver | audioXpress

The ATC was about 0.1 - 0.2% at 96dB when ShinObiwan tested it.

Over at Zaph Audio he tested the ATC and the TangBand too.

ATC: http://www.zaphaudio.com/temp/ATC-SM75-150S-HD.gif
TangBand: http://www.zaphaudio.com/smalltest/Tangband-75-1558SE-HD.gif

TangBand looks better IMO, with similar 2nd HD but much lower 3rd and higher harmonics.

Dynaudio do make a 75mm midrange sold for car use. I wonder how that performs? Esotec MD 142 - Aftermarket car dome midrange speakers - Dynaudio
 
A

Abbiendi

Member
Joined 2009
This has been tested, there are users in Japan that listen to CD as direct radiators. There was a company in AU that sold a 2-way speaker with the TAD 4001 hornless but with the back cover in place. Magnetar/others have posted this is possible. I have a 950PB with the Be Truextent and I plan to test it hornless and no back cover from 1Khz up. I have been told the lost in sensitivity will be about 10dB. We will see what is possible.

loudspeaker system,loudspeakers,speakers,high-end,audio,hi-fi,groove,vintage
 

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H

hweb

Member
Joined 2011
I had a set of those Dynaudio dome mids in my 2008 Volvo (part of the premium audio package). I have to say that it was one of the best car audio systems I've ever heard. Better than my current Lexus premium audio system (with an aftermarket sub added). I have often thought about buying a set of those "Volvo" mids to make a home speaker around.
 
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TMM

Member
Joined 2007
As others have said, xmax of compression drivers is too low to be useful without a horn. This will limit how low you can cross it without bulk distortion, and is also what makes or breaks a hornless dome midrange. The whole point of a hornless dome midrange is excellent polar response. If you have a 2-3" dome that has a faceplate that is 5-7", you need to crossover to the tweeter at a lower frequency than the measurements suggest the dome mid is capable of, otherwise the polar response of the system as a whole will be terrible due to the CTC spacing. If it can't cross to the woofer at a low enough frequency, the bandwidth you use the dome over will become so narrow that you will ask yourself why you even bothered with it and didn't just design a system with 1 less 'way'.

The TangBand 75-1558SE and ATC SM75-150S are the best dome midranges I've seen data for. Sadly both discontinued. The Volt driver is vastly inferior to the ATC from what I've seen, despite looking similar. The TB and ATC can't really be directly compared, they are different beasts. The ATC faceplate is HUGE which requires you to cross much lower than the TB, but that is no problem as the ATC low end is far cleaner allowing it to still cover a decent range and pair with a decently large woofer. The TB is cleaner in the higher freq, which can be taken advantage of since the faceplate is so much smaller - it's more suited to a smaller woofer and tweeter.

The Dayton RS52AN-8 (not RS52FN-8) is another decent performer which deserves mentioning and while it needs to operate over a narrower bandwidth than the 3" drivers, it still works very well to bridge the gap between a 6.5" woofer and 1" tweeter.

ScanSpeak / Vifa D75MX is old tech unfortunately. Overhung motor and not enough xmax gives disappointing performance compared to newer drivers with 1mm+ underhung.
 
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