Near full range BMR (Balanced Mode Radiator)

[Monteverdi]

Hi Oliver
Thanks for all your explanations and links. I did some simple measurements on the MSW using Fuzzmeasure and they are corroborating the published ones. May be I should experiment with my own bending wave design. More reading and may be then more questions for you.

[calvert73]

Hi Derek, just sent you a PM.
Regards RC

[theJman]

FWIW... HiWave is finally releasing their new BMR drivers. The 3.5" version will have a part number of HiBM65C20F-8. Parts Express should be getting them by the end of April or beginning of May. I already have my credit card in hand, waiting to place an order.

[vaugi]

4" Square

HiWave HIBM85C20-4/DD 4" BMR Full-Range Square Speaker 4 Ohm 297-2150

[vaugi]

And two HARP (High Aspect Ratio) models -

HiWave HIBM130H10-8/LP 1" x 5" HARP BMR Speaker 8 Ohm 297-2159

HiWave HIBM130H10-6 130mm HARP BMR Speaker 6 Ohm 297-2158

[Monteverdi]

I got one Hiwave HIBM85C20-4/DD and made some initial tests. Shown in a open baffle. Looks quite good for the price except the peak at 9 kHz (also high distortion). In a 3l box identical above 5khz but a -10dB notch at 3.5 kHz. I am wondering what is the optimal enclosure as some data are missing on the HiWave website.

[theJman]

Originally Posted by Monteverdi

I got one Hiwave HIBM85C20-4/DD and made some initial tests. Shown in a open baffle. Looks quite good for the price except the peak at 9 kHz (also high distortion). In a 3l box identical above 5khz but a -10dB notch at 3.5 kHz. I am wondering what is the optimal enclosure as some data are missing on the HiWave website.

There are actually going to be 2 very different 3.5" drivers, the HIBM65C20F (in 4 and 8 ohm versions) and the HIBM85C20F (8 ohm only). When I inquired as to why HiWave told me "85C was designed a while back by an audio company licensed to design BMR using our IP and the 65C was recently designed by HiWave to fulfil some other design / market requirements not met by the 85C. Also the 85C is Neo and therefore costly (it was designed pre-Neo crisis) whereas the 65C is Ferrite and therefore in a different price bracket (designed during the Neo crisis to give us a cost competitive driver)".

The 85C looks virtually identical to the driver Cambridge Audio uses in the Minx speakers, so if I were a betting man I would say they are the "audio company" who designed it. That's speculation on my part though. Personally I like the 65C better, so I'm holding out for that. It might be a while longer because the driver "is still not shipped from the factory due to some delays with engineering mass production sign-off. We are getting there but it’s been slower than expected".

I can't attach the PDF's HiWave gave me though, because they exceed the size limit on this forum. If anyone wants a copy PM me with an email address and I'll send them that way instead.

[Monteverdi]

The HiWave HIBM85C20-4/DD looks very similar to:
http://www.cotswoldsoundsystems.com/...5DD_N4Y_r1.pdf
Jman are the ones you mentioned: HIBM65C20F (in 4 and 8 ohm versions) and the HIBM85C20F (8 ohm only) similar to any BMR46 on the CSS website? These are mostly Neo and seem to be also only 2.5" but these apparently have an better highend. As none of these are complete full range I would prefer better mid and high frequency behavior even if the lows would be more restricted (higher fs).

[vaugi]

Originally Posted by theJman

The 85C looks virtually identical to the driver Cambridge Audio uses in the Minx speakers, so if I were a betting man I would say they are the "audio company" who designed it. That's speculation on my part though. Personally I like the 65C better, so I'm holding out for that. It might be a while longer because the driver "is still not shipped from the factory due to some delays with engineering mass production sign-off. We are getting there but it’s been slower than expected".

The 85 model was designed by Cotswold Sound Systems (you can see their models which map roughly to Hi-waves, on the "models" page - CSS). Graham Bank was the chief designer of BMR at Hi-wave, when it was NXT, and he has some kind of cross licence of the technology to use in his own company, CSS.

They are nothing to do with Cambridge, although CSS worked with Cambridge Audio to design the Minx (along with other BMR speaker systems I believe, e.g. Wilmslow audio).

You are right about Hi-wave designing the 3.5" version with ferrite to get over the neo costs, and you can see from this press release the large differential ($6.79/unit per 100 pcs) - HiWave: sensation innovation

I'm not sure exactly why some BMR models are on CSS but not Hi-wave (some kind of exclusivity, or marketing exclusivity?). I might ask James Lewis, the CEO, as I'm a shareholder (for transparency I thought I'd mention it too).

[theJman]

Originally Posted by Monteverdi

The HiWave HIBM85C20-4/DD looks very similar to:
http://www.cotswoldsoundsystems.com/specifications/CSS_Specification_Sheet_BMR85DD_N4Y_r1.pdf

They do indeed look very similar, but the spec's aren't the same. Even the depth of the two drivers is different, so I suspect they may actually be different.

Originally Posted by Monteverdi

Jman are the ones you mentioned: HIBM65C20F (in 4 and 8 ohm versions) and the HIBM85C20F (8 ohm only) similar to any BMR46 on the CSS website? These are mostly Neo and seem to be also only 2.5" but these apparently have an better highend. As none of these are complete full range I would prefer better mid and high frequency behavior even if the lows would be more restricted (higher fs).

The 85C does look quite like the CSS drivers, most of which share a familial appearance. The 65C looks nothing like any of the CSS drivers though. The mounting flange is round not square, the frame is far more substantial (probably to handle the extra weight of the ferrite magnets) and the surround is much larger while the diaphragm is smaller. The different 65C versions -- 4 and 8 ohm -- aren't even identical in appearance; the mounting frame and flange are similar to each other, but not the same. Even the terminals and their location differs.

The PDF's I have are marked "preliminary", but they're the most current (I got them less than 2 weeks ago) so it stands to reason they should be pretty accurate to the current drivers.