Small Driver for MEH

[Dave Zan]

If that is the OPs reason then I am surprised, I didn't think a typical conical(ish) MEH has a mechanical impedance that ever becomes sufficiently "inductive" (as it were) to be effectively nulled.
So I am keen to research this, do you have a specific reference?

Best wishes
David

 

[cowanaudio]

You can see the effect in hornresponse when you play with rear volume, even on a conical horn. Google should come up with lots of references.

 

[cemeterysounds]

What is the objective, just for isolation?
I believe there is a school of opinion that it helps the top end, but as far as I can see, that is mistaken.
So I have always wondered what was the rationale.

Best wishes
David

I was mainly doing it to get the Fb to the point where I am crossing it over. Any larger and you use a lot of sensitivity.

I have tested the 2fe22 and it seems loads better. gets a little high lower down but if I cross over at 650 it will hopefully be ok. This was at 10w it was a bit lower at less power

My test setup for this:

I haven't measured the sensitivity of it yet, next this is redesigning the front chamber and seeing whether that adds any distortion. I need to measure the cone as it seems different to the 3d model then also do some more path length correction on it so it might take me a while haha

That aspect of their testing varies in how it is plotted, what the level is, and whether a test box is used or not. That makes interpreting the plots a little harder. I looked around a bit for comparable drivers tested the same way and included a few below.

With a driver this small running free air, dipole cancellation is happening so high in frequency that I can imagine it causing accuracy issues even at lower midrange frequencies. I haven't run a distortion test this exact way, so can't say for certain what the impact is though or what conditions interact.

https://audioxpress.com/article/tes...r070wa05-aluminum-cone-full-range-2-75-driver
"For the distortion measurement, I mounted the FR070WA05 driver rigidly in free-air and set the SPL to 90dB at 1m (7.66V) using a noise stimulus. Then, I measured the distortion with the microphone placed 10cm from the dust cap."




https://audioxpress.com/article/test-bench-wavecor-s-fr4x6wa01-oval-full-range-driver
"For the distortion measurement, the Wavecor 1.75” × 2.5” oval full-range driver was mounted rigidly in free-air, and the SPL set to 90dB at 1m (6.0V), using a noise stimulus. Then, I measured the distortion with the microphone placed 10cm from the dust cap."


https://audioxpress.com/article/test-bench-the-dayton-audio-dma58-4-2-full-range-speaker-driver
"For the distortion measurement, the DMA58-4 was mounted rigidly in free-air, and the SPL set to 94 dB at 1 m (9.86 V), using a pink noise stimulus. The distortion was measured with the microphone placed 10 cm from the dust cap."



https://audioxpress.com/article/test-bench-the-dayton-audio-dma80-4-3-full-range-driver
"For the distortion measurement, I mounted the DMA80 rigidly in free-air and used a pink noise stimulus to set the SPL to 94 dB at 1 m (7.55V). Then, I measured the distortion with the microphone placed 10 cm from the dust cap."


https://audioxpress.com/article/tes...phany-pmt-40n25al01-04-mini-full-range-driver
"to measure distortion and generate time-frequency PMT-40N25AL01-04 in free air, and used a noise stimulus to set the SPL to 94 dB at 1 m (8.1 V). I measured the distortion with the microphone placed 10 cm from the dust cap."


https://audioxpress.com/article/test-bench-scan-speak-5f-8422t01-2-full-range-driver
"For the distortion measurement, I rigidly mounted the 5F/8822T01 in free-air and used a noise stimulus to set the SPL to 94 dB at 1 m (7.2 V). Next, I measured the distortion with the microphone placed 10 cm from the dust cap."



https://audioxpress.com/article/Test-Bench-SB-Acoustics-SB65WBAC25-4-2-5-full-range-driver
"For the distortion measurement, I rigidly mounted the SB65WBAC25-4 in free air and used a noise stimulus to set the SPL to 94 dB at 1 m (7.2 V). Then, I measured the distortion with the microphone placed 10 cm from the dust cap."

Wow, these are all pretty high. A lot of 2" drivers have pretty high Qts which I'm guessing contributes to this?

 

[mattstat]

I think it's more about the realities of trying to cheaply make a small driver with decent frequency response. Many are made for TVs, Bluetooth speakers, and other low power non-audiophile applications. I don't think they have the budget to do all the things they need to to get really good sound when shooting for those markets. Of the 10 or 15 drivers I looked at around this size, most didn't do very well at high or low frequencies from an audiophile standpoint. On the bottom end they tended to get muddy at moderate to high excursion. On the top end, most lacked air and detail even though many measured pretty flat (EQ helps, but doesn't fully resolve this). A "noisy" looking impulse response is pretty common with these kinds of drivers as well.

Though they cost more, the three I named earlier were some of the ones with the least problems in my tests. But I was also going to higher and lower frequencies than you are, so some of my criteria may not be relevant to your application.

 

[cemeterysounds]

Yeah, that is true. I will see how well this one works with what I have done so far.

I am planning on using 8 or 12 per mid top so want to keep the costs down a bit but also if it doesn't work then I will look at some of the more expensive drivers