..with ATC possibly being the exception for the reasons cited previously amongst others.
Well, the pro world is quite a bit larger than ATC. I suppose you are familiar with e.g. B&C, 18Sound, Precision Devices and others.
What is fascinating about ATC though is that it has managed to manoeuver very succesfully somewhere in between Home Hifi and Pro Audio, applying Pro Audio power handling standards to souped up home hifi type drivers.
Well, the pro world is quite a bit larger than ATC. I suppose you are familiar with e.g. B&C, 18Sound, Precision Devices and others.
What is fascinating about ATC though is that it has managed to manoeuver very succesfully somewhere in between Home Hifi and Pro Audio, applying Pro Audio power handling standards to souped up home hifi type drivers.
you seem to be suggesting ATC moved from domestic to pro audio, when it was the other way around? They were in business nearly 15 years before their first domestic product came out.
No, I intended to say their products cleverly fall in between Pro and hifi/home, having hifi charateristics and pro power handling and ruggedness.
Do not get me wrong L this is great compliment to a fairly small company.
Do not get me wrong L this is great compliment to a fairly small company.
ahhh. I see. Thank you for clarifying that.
I've not heard the big monsters they do, but the 50A and 100A (pre-SL days) did impress me. I would have bought the SCM-10s but they came out a month after I had just bought new speakers (I was in a bedsit at the time, so needed small).
I've not heard the big monsters they do, but the 50A and 100A (pre-SL days) did impress me. I would have bought the SCM-10s but they came out a month after I had just bought new speakers (I was in a bedsit at the time, so needed small).
I think a better way to express things might be an engineering company first and a marketing company second
The loading may be minimal, but the horn exists, and is physically large, as is the magnet. These make for a drive unit that uses substantially more baffle and requires larger spacing than a 4" cone driver.
For the referenced ATC monitor (SCM 200 ASL Pro), the mid & tweeter centres are 163mm apart.
A pair of the nominally 5.25" Scanspeak mids would easily fit this same c-to-c spacing, and are specified to handle the same power* as the ATC mids.
So it appears that the thing which makes the ATC mid a unique and beautiful snowflake is not uniquely high power handling, but that it nails a specific bandwidth better than other options.
e.g. it looks like you could get similar SPL & dispersion from:
200-2kHz - 6" cone (various)
250-3kHz - 5" cone e.g. Scanspeak 15M (SD 80 cm ²)
380-3.5kHz - 3" cone ATC (SD 49 cm ²)
600-5kHz - 2" dome, e.g. Morel EM 1308 (SD 28 cm ²)
Interesting. I didn't find that test. Is there a typo here - did you mean to say 1,000W?
The idea of 100W killing a modern high power pro driver in less than a minute seems pretty unusual - I couldn't find any information to support this.
For example, in this test I quote here, the writer intentionally overpowered some relatively small woofers (1" voice coil). To intentionally destroy them required over 100W:
"After 45 minutes of cooking (I mean testing) the speakers at 28.3 volts without any evidence they were going to fail, I raised the signal input by 1db to 125 Watts to further stress them"
Loudspeakers & Power Ratings Part III: The Test Results | Audioholics
...so surely a pro 12" with a much larger voice coil would be fine under the same conditions.
Also, the tests at Data-Bass regularly go well beyond these power levels, to see how 12"-21" drivers behave at their excursion limits, and to give power compression ratings.
I don't think he has ever reported a driver failure, which is handy, because many of the drivers he tests are on loan.
If the EAW survey was accurate (all but 2 of the 12" drivers tested died in less than a minute with only 100W) then it seems amazing that the Data-Bass testing has never resulted in a failure when applying multiple times as much power.
*I don't have the specification documents myself, but from secondary sources, I find:
Signal is described by the International Electrotechnical Commission (IEC) Standard number 268-5; it is a pink noise signal with a crest factor of 6 dB, filtered at 12 dB/octave below 40 Hz and above 5 kHz. Test duration is 100 hours, after which the speaker should not show appreciable damage.
This sounds to me like a pretty thorough test.
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Intuitively, this seems like a good thing - a large amount of the diaphragm being 'driven'.
The Morel midrange and midwoofer drivers have this too: 3" voice coils on 6" frames. Lowish sensitivity but high power handling. I'm surprised they don't get as much attention as other brands (of similar price / engineering).
But even if not an ATC fan you have to admit that those 3" midranges do look the business!
But interesting discussion.
But interesting discussion.
It's interesting how low the distortion is - I don't think shorting rings are used in the motor. Part of the high sensitivity comes from that short waveguide. One issue to overcome is the huge 17 lb magnet which may limit ultimate CTC distance between tweeter and mid or woofer and mid.
You are right. The one concern I have with the ATC mid is it's a bit too big for the X-over frequency they use. I've only seen the Zaph measurements for the non-SL unit and if H3 is 10-15dB lower on the SL that is pretty good.
These two tweeters are no or not much deeper than the ATC horn part so physically you could move them very close indeed. Don't know if the ATC magnet would affect them unduly.
http://www.falconacoustics.co.uk/downloads/Scanspeak/d3004-602000.pdf
http://www.falconacoustics.co.uk/downloads/Seas/h1396_datasheet.pdf
Or if you feel adventurous you could go the way K+H did with their O500c, discard the ATC horn and mount it with the tweeter in a combination waveguide.
People who know both tended to prefer the K+H over ATC 150s. Could be due to the WG or K+Hs use of dsp FIR filters which would have been optimized to the specific room or both. I've never heard the K+H myself.
http://www.falconacoustics.co.uk/downloads/Scanspeak/d3004-602000.pdf
http://www.falconacoustics.co.uk/downloads/Seas/h1396_datasheet.pdf
Or if you feel adventurous you could go the way K+H did with their O500c, discard the ATC horn and mount it with the tweeter in a combination waveguide.
People who know both tended to prefer the K+H over ATC 150s. Could be due to the WG or K+Hs use of dsp FIR filters which would have been optimized to the specific room or both. I've never heard the K+H myself.
Zaph tested the ATC midrange, when I saw the distortion, I wet my pants.
If they use the same tech to make some 5" and 6" midbass, god knows what will happend. But, they still, stand still.
http://www.zaphaudio.com/temp/ATC-SM75-150S-HD.gif
If they use the same tech to make some 5" and 6" midbass, god knows what will happend. But, they still, stand still.
http://www.zaphaudio.com/temp/ATC-SM75-150S-HD.gif
A few years ago I compared Avantagarde Duo (DUO - Avantgarde Acoustic? Hornloudspeaker GMBH) powered by a sweet sounding Cary Audio CAD-805AE mono blocks (http://www.caryaudio.com/products/cad-805ae/) and the ATC SCM100 (http://atcloudspeakers.co.uk/hi-fi/loudspeakers/classic-series/scm100/) powered by a solid state amp. The ATC had a much better midrange than the hornloaded 7" driver of the Duo, even if hornloading was a nice feature. The ATC tweeter was beaten by the modded Beyma CP380/M in the Duo, even if the Beyma is far from a great tweeter. The midbass of the Duo was not playing in same room almost, they were doing their thing and the horns were doing something else, something magical, yet the ATC 75mm dome did it better even without a horn. The ATC woofer was doing a good job and mixed well with its dome drivers.
After numerous homebuilt horn speakers I think neither speaker did a fantastic job. There is always better.
After numerous homebuilt horn speakers I think neither speaker did a fantastic job. There is always better.
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As I said previously, the gain from the wave guide is negligible. The high sensitivity comes instead from the motor.
Precisely! As I also said previously, the 3" dome provides a fantastic engineering compromise that combined with the other aspects of the design deliver something rather special.
Also two cone drivers do not usually form a coherent array as well as might be expected due to the decoupling. For best results some attenuation of one driver at the higher frequency end often works better.
No. ATC use their proprietary non-conductive pole pieces in their own SL versions and the two publicly-available units make do without any such treatment.
Quite different to other manufacturers' approaches, the non-conductive pole pieces produce a near pure inductance and series resistance rather than the semi-inductive impedance apparent where eddy currents are allowed to circulate (with shorting rings or without).
The effect of non-conductive pole pieces or with effective shorting rings (which for the mid-band means coating the pole tips) is to reduce predominantly 3rd order harmonic distortion. Subjectively that imparts much less "glare" or "haze" to the sound and is not remotely negligible.
Another means of removing the impedance modulating effect is to use current drive, which if other factors are taken care of, provides a simple means of evaluating the audible gains from removing this source of distortion. I urge you to try if you haven't already...
You will need to arrange a means for the current driving. Not sure what else you need me to point to?
Some "Current Drive for Dummies" and distortion measurements comparing voltage drive and current drive would be cool...
All you need know in that case is that the two distortion mechanisms described so far in this thread - namely impedance modulation from eddy currents flowing in pole pieces and resistance modulation from voice cool heating (and cooling) - produce no effect whatsoever with current drive. Measurements would show their absence but be somewhat meaningless therefore.
Subjectively the two effects are very different, however. The distortion due to the magnetic non-linearity of the pole pieces produces third harmonic distortion and its absence produces a markedly cleaner midrange. The thermal modulation is a longer term effect whereby one band changes in sensitivity compared to another so changing the frequency balance somewhat (typically making things bass-light).
But theory and measurements do nothing as well as trying it for yourself. There are other articles in the forum that discuss simple ic based transconductance "amplifiers" required for current driving. Whilst there are better methods these will suffice for demonstrating the effect of obviating the magnetic non-linearities if not the thermal modulation without too much effort.
There are further advantages of current drive that may also become evident but again there are other threads in this forum dedicated to that subject.
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