Bliesma M74 series 3” dome midrange lineup

I'm VERY interested in the measurements for all of them, though purchasing the Be version is almost certainly out of the question for me. Along with third party measurements for an anticipated Purifi small dedicated midrange and the Kartesian Wom_120. Those are the current short-list midrange candidates for my personal reference 3-way build. Fortunately, I can afford to be patient.


2004-06-21 10:19 am
the old 3inch ATC dome had double suspension plus overhung coil and a balsa wood stabilizer ring (10x3mm) recessed some mm from upper edge of the coil former ... later they gave up this concept for more upper bandwith (underhung coil)

the coil was made of flat edgewound CCAWire on kapton former

winding height 10mm and pole plate was 5mm thick

in their ads of the time they praised this driver as indestructable , taking limitless power!

they must have been on cocaine in these days!
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Here is a measurement I took of the JA-0801 (that was broken in a way where it would not play loud and still measured nice). My hope was to make the slices similar to the ones hificompass uses. I was looking for the slanted delay in time that starts around 500hz. Sure enough, it looks similar.

What happens in the first 1ms of the decay between 500hz and 5000z is something I want to focus on for my next speaker.
B.png T.png E.png

I have these lined up where about 800hz is the middle and tried to put the box at the top spl for each driver. The scales are a bit different for each graph but it is the size of the drop that i am looking for.

The first is the Be M75. The second is the 5" satori textreme. The third is the eton 3-212 mid (which I own/rock).

I was hoping not to see the steps on the M74 but maybe it is what comes with a solid dome? Or maybe it is intentional for woofer integration? It reminds me of what Ti dome tweeters do in the decay- artificial steps in time. Everything else about it looks fantastic.. well, the off-axis past 2khz is shakey too. Ah, I am reminded that no driver is perfect but I am still excited to hear a M74.


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@mbrennwa "what are those pulses that precede the main impulse?" I dunno? Maybe me letting go of the mouse? My desk is less than 6ft away from where I measured. I took a few dozen measurements and will look through them if you think it is a big deal.

Back to the decay... I think I might be missing the trick due to the angle of hificompass's graph. If I compare my ja-0801 vs hifijim's textreme vs my hexacone mid I can see the difference in the decay at 1.5khz. So now I assume the new m74 mid looks closer to the ja-0801 in that the decay is happening in very fast steps- if you look at them head-on it looks worse than what they are doing in time. Ok, I take back most rant. Anyone with REW and a new m74 Be? I'd be curious to see a waterfall with the settings in my graphs.

close_ja0801.jpg close_textreme.jpg close_hexacone.jpg
The timing of those pre-pulse wiggles is very consistent, so it can't be you or your mouse. There's something in your measurement setup.

Also, don't get too excited about comparing CSD waterfalls. Much of what you see is related to how the software processes the data for plotting. Many (most) software tools tend to smooth out those CSDs to hide the noise in the data, so the graphs are nice to look at. However, this also means that it is not straightforward to compare CSDs from different software tools, or CSDs done with different processing/plot settings. If you really want to compare, use the raw data (impulse response) and run them through exactly the same software tools with exactly the same settings.


2019-04-08 9:48 am
Good points, mbrennwa.

I looked at my other measurements and they all have a little pre-wiggle. My amp would go into protection mode when I tried to play the broken ja-801 too loud so maybe it was the mid? I dunno. I no longer have the mid since I returned it.

ETC_comp.jpg ETC_comp_aligned_32db.jpg md60n_vs_m74s.jpg

Made some more images to help me understand. Hificompass had diff. sized graphs so I had to stretch them to overlap.

Eton 3-212 vs Satori mw19tx vs Satori md60n vs BlieSMa m74b,


2004-06-21 10:19 am
Is the excitation signal white noise?

So the signal is not dynamic in nature no fast acceleration of the cone/dome then the impulse response is pure fiction only a calculated response not a real one!

Look at true music signal shapes do they sound like noize?

Science is a religion too with it's own math where you can imagine anythink :)

Heresy! Heresy! (catch me if you can)


2019-04-08 9:48 am
So the signal is not dynamic in nature no fast acceleration of the cone/dome then the impulse response is pure fiction only a calculated response not a real one!
I assume you have never used REW? Try it.

REW is playing a frequency and recording what is happening. That's it. No magic. No myth. No human bias.

Look at true music signal shapes
Music is hearing and hearing is with a flawed ear using flawed drivers. Ok, now what is true?