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**GranteedEV** · 04-30-2014, 04:54 PM

Re: Full Review of ATC SM75-150S Midrange Driver

awesome stuff... and basically what I expected.

**feyz** · 04-30-2014, 05:10 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Hi Jeff, nice review.

I THINK,the S versions are not just the big magnet used. From what I remember of their very limited and veiled documentiation there is some sort of "ring" on the air gap, but doesn't look like Faraday shorting tings. What I guess is that, they use a different material at the tip(s?) of the air gap of the magnet structure, then the rest of the steel. What I think they have, (since it is not explained in their literature) is a more linear magnetic material at the section of the tip(s?) of the air gap than the rest of the steel magnetic circuit. This material probably provides better saturation and less hysterisis due to its different B-H curve. This is my guess though. There are some old AES papers and even patents I think that use this kind of approach, they were Japanese sources from what I remember. Making the whole magnetic circuit from such metal would be very expensive, so using it in that section probably is beneficial enough.
The huge magnet also would keep the magnetic circuit into more saturation, resulting in good distortion values as well.
Again these are all guesses on my part.

**feyz** · 04-30-2014, 05:13 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Do you happen to have any off axis measurements?

**Jeff B.** · 04-30-2014, 05:31 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Originally posted by feyz View Post

Do you happen to have any off axis measurements?

I didn't. But fortunately, Zaph did:

His lines are 0, 15, 30, 45, and 60 degrees.

**isaeagle4031** · 04-30-2014, 05:41 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Excellent write up Jeff. Thank you for sharing. I would love to hear them when they are setup in his studio.

**Jeff B.** · 04-30-2014, 05:46 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Originally posted by isaeagle4031 View Post

Excellent write up Jeff. Thank you for sharing. I would love to hear them when they are setup in his studio.

I'm sure it's just a drive to Nashville......

**bkeane1259** · 04-30-2014, 06:12 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Great writeup. I'll never use that driver, but it was nice to read your review. Very well done, informative and easy to understand for noobs like me. Thanks.

**DE Focht** · 04-30-2014, 06:45 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Originally posted by Jeff B. View Post

Hi everyone,

I have been asked to design a studio monitor using the ATC SM75-150S 3" dome midrange driver. Since this driver is so hard to get your hands one, and since it has near-legendary reputation as a mid, I thought I would submit of full review with measurements and subjective listening thoughts. You can download the full review in pdf form here: https://app.box.com/s/j1pwj8exbmioz350nu0n

Comments are welcome,
Jeff B.

Thanks for the expose Jeff!

You make me miss my 150's

I'm imagining with the AE woofer and your recent trend of small speakers, the impact these new speakers can send to the listening chair probably required an adjustment.

The ATC dome turns noises into actual sounds better than any driver I know. I am glad the Raal works with the dome, I was concerned 2 drivers with such precise performance may not match well but this is great news that they worked for you. Thank You again.

**bigfishe** · 04-30-2014, 07:20 PM

Re: Full Review of ATC SM75-150S Midrange Driver

I'll be calling Mark :-D
Thanks jeff!!!

**bigfishe** · 04-30-2014, 07:21 PM

Re: Full Review of ATC SM75-150S Midrange Driver

I'll be calling Mark :-D
Thanks jeff!!!

**scholl** · 04-30-2014, 07:22 PM

Re: Full Review of ATC SM75-150S Midrange Driver

How does it compare to the 6MD38 used in the Basslines?

Thanks for the writeup

**Jeff B.** · 04-30-2014, 07:38 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Originally posted by scholl View Post

How does it compare to the 6MD38 used in the Basslines?

Thanks for the writeup

I have no idea.

**Jeff B.** · 04-30-2014, 09:27 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Originally posted by DE Focht View Post

Thanks for the expose Jeff!

You make me miss my 150's

I'm imagining with the AE woofer and your recent trend of small speakers, the impact these new speakers can send to the listening chair probably required an adjustment.

The ATC dome turns noises into actual sounds better than any driver I know. I am glad the Raal works with the dome, I was concerned 2 drivers with such precise performance may not match well but this is great news that they worked for you. Thank You again.

Yes, these speakers have Slam. They do seem to be exploiting a midbass peak in my room more than the little guys do though. I find I tend to listen to these a lot louder than I do most of my other speakers. They are just so comfortable playing at a pretty high level that I forget how loud I have it.

**ngjockey** · 04-30-2014, 09:28 PM

Re: Full Review of ATC SM75-150S Midrange Driver

Thanks Jeff.

Would like to see comparison tests to get a sense how one driver compares to another. I know, completely impractical. Different crossovers, different baffles ... For example, would like a comparison between these ATC's and Tang Band 3" dome or a BG Neo10. Not to state which is better or better value, but how they are different.