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Old 14th August 2010, 03:33 PM   #7171
KSTR is offline KSTR  Germany
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Quote:
Originally Posted by mige0 View Post
As it just fits so well what I have lots of fun to read at the moment :
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Quite so. There is one gotcha which sometimes can fool you, like tweeter tests with higher power levels involved. There I find power compression visibly influence FR's obtained from logsweep+convolution, depending on the sweep direction. One might precondition the driver to factor out power compression.

- Klaus
consider that preconditioning would need to determine the main thermal behaiour of the speaker at first - as there is no other way to precisely hit thermal steady state (equilibrium) during measurement otherwise.

This is of course of a nitpicking point of view - from a more practical point of view - as you most possibly meant it - quite *any* pre-heating in the same order as the measurement signal will improve the situation.

Michael
Michael, my somewhat more hidden point (not especially addressed to you) was that the impulse from a top-down sweep + convolution on a tweeter with power compression still leads to a valid capture of the stimulus-dependent behaviour. If you play back the same logsweep convolved with that impulse you will get exactly what the microphone saw in the time domain. In other words, the impulse is just the very one needed for a perfect LTI system to then (and only then) faithfully reproduce the original time response when fed with the original stimulus although the original system was sligthly and slowly non-LTI. Faster nonlinear waveform distortion can also be reproduced (with a bit of math involved) when the impulse response contains extractable harmonic impulses in the pre-echos.

Besides preconditioning, compression from DCR rise can be factored out when using current drive (needs preequalizing when you hit impedance preaks).

- Klaus
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Old 14th August 2010, 05:09 PM   #7172
JohnPM is offline JohnPM  United Kingdom
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Originally Posted by Elias View Post
Your analysis is too simplisctic.

Instead if you write
(0 + |e|)*(u + |e|) = 1
where limes(e) -> 0 and limes(u) -> oo
it can be seen that CMP system can be equalised with an equaliser having impulse response h where limes(h) -> 0 and limes(length(h)) -> oo.
Elias, now you're posting gibberish, which is in danger of becoming your trademark. No matter how much sophistry, wishful thinking or self-delusion you multiply that zero by or convolve it with, it will stubbornly remain zero. You're still making the effort though, despite an increasing resumé of gaffs, so I'll be charitable and tell you what you should have said.

If the null in the response was the result of a single delayed copy of the input after time T, an equaliser could be constructed with tap values of (-1)^n, n=0..infinity at intervals of T. The earth-bound among us would look at that infinity and conclude such an equaliser was not going to be much help, given our finite resources. It's success would be rather transient . More serious though, especially for our unfortunate listener, is that we're going to have to nail his head to the floor because the slightest change in the delay of that echo would ruin the whole thing. I'm not sure who is worse off, the listener or those of us posting in this thread.
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Old 14th August 2010, 07:55 PM   #7173
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Originally Posted by mige0 View Post

Once again Lynn - thanks for the great platform you allow here

Michael
When the cat's away the mice will play (old English proverb). I've been buried in the arcana of 5 to 7-channel home theater systems with the arrival of the Panasonic 58" 3D plasma TV, 3D-capable Panasonic Blu-Ray player, and the latest Comcast/Motorola HDMI-interface cable box (3D-capable also).

Have discovered some truly remarkable HDMI bugs, like the ability to lock out all remote controls until the power is cycled on one of the devices. This is a really weird protocol - DVI with an additional layer of unwanted and bizarre inter-device communication. I understand Hollywood and Congress are the bad guys here, with legally-mandated inter-device authorization protocols that still have a lot of rough edges. HDMI does work most of the time, fortunately.

Will spend today with Karna out of the house - gone shopping with our daughter-in-law and grandson - doing noise-burst auto-measurements of the HT setup. The ancient 2805 Denon receiver uses a crude form of digital parametric EQ, but it should still be interesting seeing just how mismatched the new Center speaker will be. I'm hoping the $3200 Dynaudio SC X center speaker will not need a lot of equalization, but the (admittedly crude) Denon measurements will tell the tale. Over at the AVS Forum, the latest super-duper versions of Audyssey are purportedly capable of sonically acceptable results. Maybe.

The HT world seems to have very different expectations of what music should sound like than I do. Finding an even halfway decent Center speaker turned out to be a major project, and the sound of nearly all HT receivers is truly dreadful. The only one I've warmed up to has been the Marantz AV8003/MM8003 combo - at a mere $5000 price. The Anthem pre/pro and amps, nope. Any Denon, nope. Onkyo, maybe OK, but on the murky side. Pioneer Elite, tipped-up and edgy. Audiophile exotica - no thanks.

It has slowly - very slowly - dawned on me that the HT reviewers have little or no experience listening to unamplified acoustic music, while that's the only thing I'd consider using as a sonic yardstick. HT dreck does explosions, car crashes, and similar adolescent movie fare just fine - but music? Not so much. An iPod Touch & Sennheiser HD 580 phones sounds better than most of this stuff. Very, very thin pickings if you're the kind of person that actually prefers music to the latest Hollywood action movie. The HDMI fiasco has driver most of the specialist manufacturers out of the HT sector, but then again, I don't care for audiophile transistor products anyway, so no loss from my perspective.

As for the now-famous measurements of the TD15M, I did briefly consider an square or diamond array of 9 Vifa 5.5" drivers to get a similar efficiency. But I don't like non-coincident arrivals from large driver arrays - it was a bad enough problem in the Ariel with its compact MTM, and I'd expect a larger array to be worse.

So it came down to subjective and measured preferences with 12 and 15-inch drivers - thus, the TD15M (or Altec/GPA 416) combined with a large-format compression driver and a low-diffraction horn with a smooth falloff on the edge of the dispersion pattern. In some ways, a modern version of the Lansing Iconic studio monitor or the Altec Model 19.

Last edited by Lynn Olson; 14th August 2010 at 08:22 PM.
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Old 14th August 2010, 08:05 PM   #7174
Pano is offline Pano  United States
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Hard to beat a classic.

As for HDMI, the cable is cool, the protocol is not. Systems installers and manufacturers are like Extron are already running into huge problems with systems that are only slightly complex. Too many restrictions and bugs. It's a nightmare.
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Old 14th August 2010, 08:41 PM   #7175
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I guess I was foolish in expecting high-dollar HT to actually sound good, while mainstream high-end audio doesn't. Gritty generic transistor-amp sound everywhere, audibly and measurably inferior to the 33-year-old Audionics CC-2 amplifier designed by the late Bob Sickler.

This is just inexcusable; good transistor-amplifier design principles have been known since the early Eighties. It's not complicated: adequate and linear current delivery in the driver stage, adequate phase margin with any likely speaker load, a full-power bandwidth at least 3 to 4 times the maximum audio bandwidth, and some attempt to lower rectifier noise in the power supply. I don't see any of that done in the HT field, while we took all of this for granted back at Audionics a third of a century ago.

Either the HT design guys don't know or don't care. I'm appalled to see the art actually go backward over the last 30-plus years. Transistor amps don't have to sound gross; they can actually sound halfway decent if a modicum of care is applied to the design. But it just doesn't seem to be there, with the exception of a handful of products. I'm trying to track down the schematics of the Marantz and Onkyo products, to see what DACs, opamps, and power-amp circuits they are using, but this appears to be Super Secret Eyes Only information, despite the fact that most of these multi-thousand-dollar products are made in a handful of factories in the Shenzen region of China. The Chinese are certainly aware of the schematics, since they're the ones that build them; why the secrecy from the rest of us?

Last edited by Lynn Olson; 14th August 2010 at 08:52 PM.
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Old 15th August 2010, 01:11 AM   #7176
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Default That artifact

Quote:
Originally Posted by augerpro View Post

From John J's comments I take it that this is a suspension or cone issue. It is not as noticeable with the fabric surrounds, although it is still there. It is also most noticeable on the 15" drivers. My guess is it is cone/surround interface issue. Similar to the dip you see around 800-1000hz, on smaller drivers, especially 8" woofers for whatever reason. Or cone flex issue that is mitigated by fabric surrounds but not helped by foam surrounds.
If so it might be interesting to add (temporary) additional to the cone or surround to identify the source.

VAF Research have been doing this on their DC series speakers for more than a decade - the DC-X was, in some ways, solving a similar problem to the question the Ariel answered.


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Originally Posted by augerpro View Post
Anyway I haven't seen any big woofers with better IR than the AE drivers so not sure what the fuss is about.
Or one could leave it well enough alone.
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Old 15th August 2010, 02:43 AM   #7177
soongsc is offline soongsc  Taiwan
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Having listened to many high priced stuff, nowadays, I'd start looking from the lowest price reasonable and work up the price latter till the sound is reasonably well.
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Old 15th August 2010, 03:06 AM   #7178
ScottG is offline ScottG  United States
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Originally Posted by Lynn Olson View Post
..and the latest Comcast/Motorola HDMI-interface cable box (3D-capable also).


..Over at the AVS Forum, the latest super-duper versions of Audyssey are purportedly capable of sonically acceptable results. Maybe.
The only one I've warmed up to has been the Marantz AV8003/MM8003 combo - at a mere $5000 price. The Anthem pre/pro and amps, nope. Any Denon, nope. Onkyo, maybe OK, but on the murky side. Pioneer Elite, tipped-up and edgy. Audiophile exotica - no thanks.

Is is 1.3 or 1.4? 1.3 will pass through 3D at 1080i, 1.4 will do 1080P. (..something to look at with the various receivers/processors.)


This one will "only" pass through 3D at 1080i.. (currently).

Emotiva Audio UMC-1 Audio-Video Processor

That in combination with amplifiers of your choice may be a better option. It isn't an Audyssey solution, but I've read opinions where the very best integrated Audyssey stuff wasn't that great. (and Emotiva's pricing isn't exactly consumer gouging. )

There policies aren't bad either:

http://emotiva.com/whybuy.shtm
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Last edited by ScottG; 15th August 2010 at 03:12 AM.
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Old 15th August 2010, 03:56 AM   #7179
soongsc is offline soongsc  Taiwan
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Originally Posted by Lynn Olson View Post
...
Either the HT design guys don't know or don't care. I'm appalled to see the art actually go backward over the last 30-plus years. Transistor amps don't have to sound gross; they can actually sound halfway decent if a modicum of care is applied to the design. But it just doesn't seem to be there, with the exception of a handful of products. I'm trying to track down the schematics of the Marantz and Onkyo products, to see what DACs, opamps, and power-amp circuits they are using, but this appears to be Super Secret Eyes Only information, despite the fact that most of these multi-thousand-dollar products are made in a handful of factories in the Shenzen region of China. The Chinese are certainly aware of the schematics, since they're the ones that build them; why the secrecy from the rest of us?
I think what we are experiencing is a product that meets spec with the lowest recurring and non-recurring cost possible. Even in the software world, we see this happening. Does this mean the days of having schematics in the manual are over? This is the way it seems because everyone is headed towards commonized modules for the consumer market. Some here opened up a Goldmund CD player and found the main circuit board that was pretty much the same as a popular consumer brand. The schematics are probably in the hands of some unkown smaller OEM factory.
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Old 15th August 2010, 04:16 AM   #7180
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Originally Posted by ScottG View Post
This one will "only" pass through 3D at 1080i.. (currently).

Emotiva Audio UMC-1 Audio-Video Processor

(and Emotiva's pricing isn't exactly consumer gouging. )

There policies aren't bad either:
Emotiva HQ is just a couple of hills away from my place and I thought I would go over and check 'em out at their upcoming "Emofest". If anyone else is local it would be a good chance to hook up at the show.
Emotiva Audio: Audiophile Quality Multi Channel Amplifiers, Stereo Preamplifiers, Audio/Video Processors, and Award Winning Speaker Systems At Direct Prices

I have not had a chance to see or listen to their gear so it should be interesting. They will have some live musicians at the show - http://compassrecords.com/alison-brown - (it's pretty easy to find musicians around the Nashville area) so comparing "live sound" to their equipment will be interesting.

I'm interested if they actually make their gear there or sub it out to you-know-where.
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Last edited by c2cthomas; 15th August 2010 at 04:18 AM.
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