Adire HE10.1, HE12.1, Beta8A

[oneoldude]

I am working on a three-way High Efficiency dipole for a friend who purchased a SET amp and I have no experience with High Efficiency drivers. My choices for the M are Lowther, Fostex and the Eminence Beta8A. There is much published on the Lowther and Fostex drivers but nothing on the M8A. So I am trying to get a handle on how the Beta8A measures and sounds. Since I can not find anyone with measurements or experience with the Beta8A, I am hoping that those who have heard the Adire 10.1 and 12.1 will reply because the MW drivers are Betas in both cases. I hope there is a family resemblance between them all and I can at least get an idea of the "flavor" of the Beta8A. So:

How does the HE12.1 sound in the mid range? Especially in comparison to Lowther and Fostex units? How about vs high-quality low efficiency M units?

Has anyone any experience with the HE10.1? How does it sound in the mid range vs Lowther and Fostex? How about vs high-quality low efficiency M units?

Any comments, observation and suggestions, including drivers not mentioned above, are welcome and appreciated.

[Saurav]

Try the high-efficiency forum on Audio Asylum, you'll probably find more people who've heard these speakers. I've heard/owned the 12.1, and I think it's strengths are its dynamics, impedance, step response, etc. ... not the smoothness of its midrange. I've heard people say that the 10.1 is better integrated through the midrange. There are a few reviews of the 10.1 available online.

[Jam_Master_J]

I was looking in HE 10.1s for quite a while, but ultimately decided to spend some more do M8/RS28 based MTM design. However, I've heard the HE series is pretty satisying for music. One complaint I heard was that the off-axis performance wasn't great but most comments were positive other than that.

[joecarrow]

I built a pair of Beta-8a mass-loaded transmission lines last year, and I was really happy with the midrange. I didn't know a lot about speaker design at the time, so I tried to do something I could learn from and not mess up too badly.

Partsexpress has the frequency response for it- here . The way I did my crossover was a first order lowpass on the woofer at a bit below 4 khz, and a first order highpass to a Morel MDT20 at around 5.5khz. I didn't use any software to plan that, but I knew that a first order crossover would at least keep me from worrying about phase. The spread between crossover points was supposed to counteract the rising response of the Beta-8.

In the end, the response wasn't too flat. I used a parametric EQ on my PC to fix things, mostly cutting from 1khz to 5 khz by 3 or 6 db, adding a boost from 40 to 300 hz, and a sharp highpass for the whole thing at 30 hz. Equalized like this, I still had trouble from running the 8s too high and getting beaming (easy to tell off axis)- but overall, people noticed that this system had really low distortion and great dynamics... but it was excursion limited down low.

For your application, I think you should look at its Xmax, Qts, and sensitivity within your desired passband. I have a lot of praise for what this driver can do, but I'm not so sure it's right for your application.