Hi Vi M8

[GeorgeS]

Several interesting projects here include the Hi Vi M8a. Parts Express shows this as discontinued on their web site. They carry the M8n, which seems quite similar but is obviously a different model. I seem to remember reading something about the M8a motor that I didn't see in the M8n 'blurb'. How does this driver compare to the M8a?

On a more general note, suggestions for a 6.5 to 8 inch driver (bonus points for shielded) for a small enclosure (8 to 18 L) would be gratefully received. Plan is to XO at ~500 Hz and apply Linkwitz transform to compensate for cramped quarters and extend LF. Quality and range are primary concerns but only modest SPL.

Thanks very much.

[ThomasW]

Hi and welcome to HT-Guide,

Although we haven't had one to measure; the expectation based on what we read, is that the M8n will be a drop-in replacement for the M8a.

I doubt that production of the M8a has been discontinued by Hi-Vi. I think that PE no longer stocks it given the cost. In the past PE has been willing to special order drivers that they've 'discontinued'.

The M8a/M8n can be effectively shielded after the fact. I helped a friend build a horizontal MTM that's positioned directly under CRT, mounted in an entertainment center. We lined the cab with 2 layers of thick sheet metal and glued 9oz bucking magnets on the drivers. There's absolutely no interference with the TV.




theAudioWorx
Klone-Audio

[Dennis H]

I think the main difference is the "a" series has a cast frame and the "N" series has a stamped frame. Motors, etc. should be very similar if not identical.

[GeorgeS]

Thanks for the quick replies.

They look very similar as do the numbers but I figured it would be better to ask than assume.

I was planning on doing the sheet metal lining thing if I ended up with an unshielded driver. I've seen drivers with bucking magnets but don't know anything about how they would be selected or applied. Could you point me at a reference?

The project is actually for 2-channel music, but the speakers will be near a monitor (major overkill 'computer speakers').

[ThomasW]

I don't have a reference for bucking magnets. The idea is to get one that's about 50% the weight of the magnet on the driver.

We used 9oz on each M8a, as I recall the Hi-Vi magnet is ~20oz.

We built the cabinet a little differently. We built an outer 3/4" MDF box, and lined the inside of that with sheet metal. We then built an inner box, again 3/4" MDF, we line the inner box with sheet metal as well.

The reason for this was the fact that his 32" CRT would be sitting directly on top of the speaker. I wasn't sure if this concept was going to work. I was thrilled when we set it up, and the TV picture was perfect.

BTW, Parts Express and Madisound sell bucking magnets




theAudioWorx
Klone-Audio