ATC SM75-150S Dome Mid Measurement Data

Never said I was 'better' than ATC just that my design is a more linear. Why is that so difficult for you to understand? I'm guessing its because you don't understand half of what were talking about and just see the words 'ATC' and 'can be bettered' and then go into your usual one dimensional self.

and again

and once more

Maybe it just sank in now.

 

Absolutely,

But your post clearly demonstrates that you've never heard the 2001 and that you are totally unfamiliar with the differing beryllium drive units employed in both that Usher and the DD66000 - let alone any other design details.

Given that your ignorance of the subject matter shines through, don't you see that posting comments like the idiotic one ascribed to you in the link puts your position of authority into some perspective for those with genuine experience?

I agree with Bub frankly. I find you utterly repulsive as an individual.

You've sent offensive and unsolicited PM's to me

You've insulted me on numerous occasions and inferred that one of the moderators is biased

And now you've called another member a Spastic.

Utterly disgusting.

 

who gives a shit about measurments anyway
its what it does to your head & heart that counts
stop bloody fighting!!!

 

Dunc,

a clue would be that ATC bass units do not like to be run very high up. Crossing them over low can reduding spurious output from early cone breakup that completely dwarfs any supposed distortion benefits in the mid, and causes excessive energy in that area to distort the picture as a whole.

The solution, as used by some manufacturers is to use an alternative source of bass driver.

All the measurements show is that the ATC mid is capable of being a decent midrange driver. They are not enough to discredit ATC, nor to give any indication as to the performance of the posters home made speakers.

 

Its a sad fact that this thread started off about measurements and moved past that to topics completely superfluous.

Its good to see that with the exception of the insult, people agree with me(cheers for the PM's), I don't always write in the best style but I certainly know what I'm talking about having large amounts of practical experience unlike the arm chair designers, especially in regards to ATC where they can only summise based on virtually zero measured data. Its a shame that my enthusiasm and knowledge is undermined by a couple of individuals.

The acts in correcting my misinformation peddling are commendable(and transparent) but I suggest SM move on.

Despite the drama I still think a good discussion can be had.

Dunc:

Good questions (some at last!)

Most of the ATC loudspeaker range, with the exception of the lower end, use SL or Super Linear drive unit technology. SL is basically a non-magnetic material in the bass driver's motor which helps decrease higer order distortion products caused by differences in the magnet force relating to the magnet material leading to an effect called hysteresis.

ATC use this driver exclusively in their own products, its not available to the DIY'er nor to OEM's. Instead what they have available is a range of drivers that are built on the same basket, cone material and voice coil(VC) but have a motor sans SL technology. Available to the DIY'er are two variations on the 9" and 15", the variation are differing VC topologies. The short coil version is an underhung design which offer a more linear BL product with varying excusion as opposed to the long coil version which is overhung and offers higher efficiency and output.

I use the 9" SB75-234SC which is the shortcoil/underhung design.

So ATC use a different bass driver that I have no measured data on and only subjective experience. I've said it before but one unlikely reason for the lower XO point on the bass/mid transition is that the ATC SL drivers don't go up high enough to be usuable in those regions. So it could have been a lesser of two evils - problems with the mid or problems with the bass driver. However given the measured performance I have on the 9" SC - that shows its quite linear upto 2.5Khz, I'd suggest that that not be the case as with 24dB/Oct filtering the response would be around 55dB down at that point.

Here's the measurements I took on the 9" SC late last year:





Conditions were 1w/1m.

In light of this and the fact that ATC wouldn't design a bass/mid driver for a 'high performance' loudspeaker intended to cross at 380hz that didn't actually extend a good way past that, I'd suggest that wasn't the reason for the lower XO point.

So its unlikely that the bass driver can't actually cross higher. What does that leave us with?

Another consideration is voicing and maximising the range that mid driver covers. Crossover points are often ugly things and having one right at 500hz is in one of the ears more sensitive regions so lowering it may have been subjectively better at the expense of linearity of the design as a whole since they're using the mid where distortion starts to sky rocket near driver resonance, However, given digital crossovers, phase problems at the XO point can be virtually eliminated on axis and the ATC also lends itself well to a superb power response which also means good linearity off axis too. This was the gist of my point all along, the digital XO's allow to move the XO point up, improve driver integration and allow more linear operation. Whilst we know that ATC use the 9" SL rather than the SC we can take it as a given on the performance of the mid because that is exactly the same as the one I've shown data on here and distortion is bad low down, so being sensible about things we'd like to avoid that rather than start to use it at 380hz with shallow filters.

I seriously doubt any ATC representative would touch this thread given what's gone before. A real shame because they'd be able to say exactly why they did what they did.

As it stands we have measured data on the ATC mid which shows where the driver is most linear and where its not. Someone designing the for the most linear operation will make sensible decision based on that data.

The debate isn't "ATC made a bad speaker but why?" But rather "hey this can improved for more linear operation". Of course I have radically different XO topologies to the ones ATC decided to use and these are both more flexible and costly. The ATC mid benefits from these more extensive crossover technologies.

 

Its bub reading into things too much.

I'm not sure if your aware of this but the ATC midrange driver has a strong following, much subjectivism or opinions on its performance but very little objective or measured data.

You never know really where you are with subjectivism, especially when its a bunch of folks on a forum arguing that they heard lots of 'air' etc. etc. But once you understand how to interprete and read the measured data then that certainly gives a clear picture that's based on facts rather an infinite number of variables based around 'this is what I heard' type conversation.

The ATC mids are expensive drivers at £390 each. That's most likely why their held in such reverence.

The reason why I posted data was to show others what it can and can't do. As well as give further evidence as to why some do and some don't like ATC's.

I'm no self appointed expert, I listen to others and base my opinions on plain and simple experience. If I don't know I'll keep quiet. In the case of the ATC mid, I know it well after nearly 2 years designing around it.

 

Can I just ask shinObiwan whether he has actually heard this driver (ie. the one he supposedly subjected to all his measurements) in the actual ATC products for which is was presumably designed? I may be wrong but I am going to assume one such product is the SCM100, as used by bub and fox.

After all, surely if it works in these speakers then it does, for me, question the relevance of these single-driver measurements in the first place - not that I can understand any of them anyway

 

I've pruned the thread and deleted all posts that contained personal insult(s) or any subsequent reference to it. I know that I have deleted some very good posts as well but I can't sit here and edit literally dozens of long posts. Please refrain from personal attacks. Despite what some people might believe, this is against the AUP and is taken very seriously here. Such offences can result in a permanent ban.

If any of our members find themselves at the receiving end of such attacks, please report the post. Don't react yourself.

Thanks for your cooperation.

 

...

 

Unfotunately Bub is right, I have no idea what I'm doing:





The next project will likely be the same shambles too:

 

These speakers are placed pretty close to a corner. Does that sound right?

 

I've noticed since I've redone the room and removed the treatments the overall sound has become less transparent and they don't quite image like they used to, despite my best efforts. They're firing along the length of the room in that shot. Before saw them on the width of the room which gave well over a meter between the sidewalls.

Bonus is a pretty flat bass response to 30hz with only a small amount of EQ needed to flatten the peaks at 40hz and 90hz.

I had plans for some new treatments but that's a bit up in the air because of a move.

Your right though, its not ideal and, compared to running them along the width of the room, doesn't make the best use of the speakers.

 

They look smart - I reckon bub should make you an offer!

 

Don't know about Bob but I'd be proud to own them, if only for their looks. Obviously can't comment on the sound as I've not heard them but expect them to sound good.

 

Shin, looks like you plan to use the Manger driver.
Heard great things from that recently.

 

Really Rob?

Could you give an account of what you heard and some insights into the sound?

Thanks
Ant

 

I heard the Oerkill Adio speakers at the Heathrow show which use the Manger with two open baffle bass drivers.
Two things stood out. Firstly, the image lacked the usual smear seen to some degree in conventional two way speakers - the sound was rock solid and bold. Secondly there was a very noticeable lack of top end spit and grain. I think the Manger is a very clean driver.

I've head it in a different configuration but can't go into that here. The same stability, precision and lack of distortion was in evidence in both designs.

Bloomin expensive though - I wouldn't wanna slip with the screwdriver

 

EDIT: The guy's not worth a reply.

 

Thanks for that Rob

Could I press you for a little more info?

Obviously much is down to implementation but how would you rate the dynamics in the range the Manger was covering(I believe its 300hz up on the 3-way Finale). The only real concern I have about adopting the driver is a few reports of a laid back nature that does rock, dance and other high energy music no favours. These few comments also went on to say its really best suited to jazz, acoustic and smaller classic pieces, I believe this was in reference to the zerobox 109 implementation which by all accounts is a far lesser speaker than the Overkill Finale and Encore loudspeakers. I'm hoping to get some opinions from Simon who also uses the Manger but its a bit of deal breaker for me as I like a wide variety of music and often find myself listening to the likes of The Prodigy, Tiesto, Massive Attack, Chicane and so on.

Any clarification would be excellent and much appreciated.

 

Praise for the Manger driver at the heathrow show isn't universal (when is it ever however?)

I listened for a couple of minutes, and thought it sounded pretty awful to be honest.

I've heard the driver sounding better in a pair of.....ahhh what were they.....it'll come to me..

but to be honest, I don't rate the drive unit, I've never heard it sounding as good as the best of the rest.

I reserve the right to change my opinion if shown the error of my ways.