ATC SM75-150 versus SM75-150S

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From what I have read, the only difference is the sensitivity increase for the S version. The cone assembly is the same for both (the same recone kits work for both versions). If you look at pictures of the units, the S version has a much bigger/stronger magnet which provides the sensitivity increase.



  • ATC SM75-150.jpg
    ATC SM75-150.jpg
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  • ATC SM75-150S.jpg
    ATC SM75-150S.jpg
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That looks very similar. We could just cross the tweeter a little lower to get more detail in the lower highs. I don't know. :S

But where to find them for cheap?! On a students budget I will only afford one. Called ATC in the UK and they wanted ~300 pounds for it.

Oh, and ATC is keeping the S version to their own speakers now, I asked them on the phone. So this discussion is pretty fruitless.

I am planning to use my single, mono :( SM75-150 driver to build a ATC SCM50 clone to go with my Krell KSA-100 clone, of which none is of course completed. I happen to have the chinese made tweeters from the ATC SCM16A (still on ebay for $21: "atc tweeter") and a pair of unknown ATC PA75-260 STD 8 ohm (!). Not the -314. Not the -243. Not the -234. But a rare -260. I measued also. 255mm across. It likes to be between 250Hz and 900Hz. They are very revealing. I played it a long time before they loosened up a bit, or my stereo warmed up properly. I was scared the first two days and thought, "what a crappy speaker I bought!" We will see if I can decide on a cabinet for these rarities. 255mm is not 243mm across, like in the original SCM50.

I asked ATC and they didn't have anyone old enough to answer what they were. Does anyone here know? I need to know things like cabinets, and if the official scm50/100 crossover still works.

I know I am kinda hi-jacking the thread, but it is on the topic of using the SM75-150 in a sensible way. And since nobody can really buy the S version anymore we could just talk about my speaker project instead. ^^,
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Solen will sell you both version, but they are more expensive than direct buy from ATC.
I find the price quite right compared to compression drivers and horns...

True, true. Good compression drivers are equal in price. It is not like I have to buy the worlds best speaker more than once.

It is interesting that you mention compression drivers. Maybe the SM75-150 is considered to be a compression driver, but I am thinking more of TAD, JBL, BMS, etc, when I think of CDs. How would they fare against the SM75-150? The Avantgarde Trio is considered by many, not all, as one of the finest speaker in the world.
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