HI-VI M8A 8" how good are this drive??

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but im most interested in the 8" drives from hivi...

Those are the M8a. Browse around that forum and you will find several projects using them - WT and WTW in ported boxes as well as the big dipole where they are used as mids. Good drivers but they need to be crossed pretty low because of a resonance at about 2500 Hz. Jon crosses to the tweeter with a quasi-8th order Cauer elliptic filter at about 1250 Hz.
 
Im Using the M4N along with the Tang 2" with phase plug in a .75 ft^3 ported cabnit and i am shocked at the bass extention of the little 4" driver. Im shockes that it has somthing you can almost ;) call punch down to 45 hz. I am a big fan of hivi now, for the price there better than vifa imho.
 
All the projects using the M8a detailed on HT-Guide and the links in my signature started from an article in the Sept/Oct/Nov issues of AudioXpress. The M8a-MKIV. That design is ported. And several people have built other ported versions.

We've also used the M8a drivers in several dipole designs. They are VERY good drivers for the money

Below is the original posted TM design that was detailed in AudioXpress

M8-IVNoGrilleSS.jpg


Below is copy made into a floorstander

An externally hosted image should be here but it was not working when we last tested it.


Below is the M8a-MKIII it has a Focal TC120 tweeter

An externally hosted image should be here but it was not working when we last tested it.


Below is a variant, it's ported and is using a Hales tweeter

LivingRoomW_DrvrsSS.jpg


The speakers shown below are ported

An externally hosted image should be here but it was not working when we last tested it.


Avro Par't design dipole

An externally hosted image should be here but it was not working when we last tested it.


An 'extreme' version of the Arvo dipole

An externally hosted image should be here but it was not working when we last tested it.


Click on the link to see another ported MTM design.

attachment.php4


There are 1/2 dozen or so more designs we've created using the M8a driver. But I think this is enough of a sample to see that we think it's a good driver in many applications
 
Here's a link to the important files that relate to the M8a-MKIV version Vifa XT-25 tweeter (there are other tweeters that will just drop into this design, one is the SS9800).

If you use a sub a sealed box is fine. If you're not using a sub, I recommend going ported to lower the excursion of the driver.

http://pwp.t-3.cc/ttriff/M8aArticle/

If you want all the R&D info related to the design, buy or borrow the back issues of AudioXpress.
 
I found and uploaded a rough draft of the text only of the AudioXpress article. You can download it at THIS link.

Although incomplete since it's a rough draft and is lacking the supporting graphics, it will give you some idea of the rather exhaustive research that went into the M8a- MKIV design
 
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