[John Ashman]

nt

[ctviggen]

But how can one even know what the event is supposed to sound like?  My CDs don't sound anything like the concerts I attend.  For instance, I don't think I could ever place the bass player on stage just by using my ears (I'm talking amplified rock concerts here, with extra speakers).   Most times, I can't even hear the words as everything is turned up so loud.

[doug s.]

...If this piques your interest at all, browse to ambiophonics.org and start a little bit of reading. This isn't just another audiophile tweak, it is the real deal and once you hear it as I've had there is no going back if real reproduction of the even is the goal, not just audiophile hi-fi sound....

funny you should mention this site.  a few years back, i purchased three jvc xpa-1010's direct from jvc - they were sitting unused/unsold in one of their warehouses.  they gave me a good deal, to get rid of 'em; i sold two to ralph glascal to help subsidize the purchase of the one i kept.  a great li'l dewice, imo, for imparting that *live* sound to conwentional 2-channel audio.  unfortunately it was the wictim of a personal family dispute, & ended up in a pile of little pieces.     oh well.  at least i am still here to tell about it!    

this is the only way i am presently interested in doing surround sound - from properly processed signal derived from conwentional 2-channel audio.  perhaps i may run across another xpa1010, or something else similar & relatively inexpensive will be deweloped in the marketplace, in the future.

regards,

doug s.

[JoshK]

Yeah I've been looking for one of those too, but shhhh don't want that much competition.  Actually the JVC is only part of the solution, the other part isn't as easy because there is no off the shelf solution.  

Bob, I understand where you are coming from but when you hear Frank's system I think it answers questions that I could never explain to you satifactorily.  Basically though, Frank's system allows you to choice the approximate venue size, say Jazz club for a rock recording (not live), or concert hall for an orchestral piece and then the acoustics choosen actually matches what is on the recording so you really think you are in that venue.  It isn't like the cheesy DSP stuff inside most mass market receivers, JVC actually went around and measured a lot of popular venues and got really info, this meshes well with the ambiophonic processing of the stereo to give a really realistic reproduction.  If you close your eyes you can't tell that you aren't there from the spatial cues alone.  

There are many other benefits to this system as well that I have never experienced in my hi-fi or any other hi-fi system.  One is that when Frank played an old LP that had some surface noise, the surface noise was completely non-irritating.  It was on a totally different realm, not part of the recording.  This is what Frank analogized to like a baby crying in a concert.  You hear it but if you are into the music it isn't part of your focus and all background noise in this system was like that.  This is a lot different than background noise in my system, which gets confused with the spacial information and becomes fatiguing.  Another is that imaging is real, not hyper real like stereo and doesn't shift or change when you move to the side a few feet, instead only the direction of the image towards the center changes, which is like what you would hear if you were there.

[csero]

i believe the purpose of hi-fi is to enjoy music.  to reproduce the musical ewent is a misnomer, in most cases.  sure, some music is live & unamplified.  but, unless yure listening only to classical music, this is not the majority of what yure gonna be hearing.  even if you go to a live music concert.  the "musical ewent" is usually amplified electronically, if live, or recorded from highly-proccessed multi-layered tracks from individuals in small soundproof rooms.  and, in many cases, the sound i hear from ...

So you are also an audiophile who could not change to something better, because you think your sound is better than the original. You don't "prefer accurate musical reproduction",  and can't "easily identify it when you hear it"  because it is not as pleasant as the sound of your hi-fi.  

[doug s.]

You mean like the guys that buy a hot car and then are to terrified that it will get a nick in the parking lot that they begin stalking people in the parking lot? Or are you talking about the guys that have all these nice cars that they spend more time buffing than driving?  

YES!!!  

plus, ya forgot all the folk that think their cars are the best, yust cuz they cost more than a lot of houses...    

there was a recent thread about cars here.  (moved to the fight club, i think.   )  seems a lot of folks are pretty perturbed (in the automotive community also, not yust here), that the mitsu evo can spank the pants off lotsa cars up to three times (or more?) the price.

as the owner of alfa romeo daily drivers, & a weekend de tomaso pantera "fun" car, i know what this is all about.  i guess i have the same outlook about cars as i do re: audio - champagne taste, beer budget; so i yust look for the best end result possible, on a shoestring budget!  

regards,

doug s.

[doug s.]

So you are also an audiophile who could not change to something better, because you think your sound is better than the original. You don't "prefer accurate musical reproduction",  and can't "easily identify it when you hear it"  because it is not as pleasant as the sound of your hi-fi.  

frank,

it is a misnomer to say the *original* is real, if it is amplified, & heard thru a pa system...  what part of it is real?  and, what i said is not an absolute.  *many* times, i come home from a concert totally wowed.  so, you cannot judge whether or not i prefer accurate musical reproduction, or whether or not i can "easily identify it when i hear it", based upon what i said.  

the point i am making is that at least 95% of music software has absolutely nothing to do with "accurate musical reproduction", so this term "accurate musical reproduction" is meaningless.  what i enjoy is music.  sometimes it sounds "natural", sometimes not.  and, i do not choose to listen only to software that has been naturally recorded.  i listen to music i like.

i also find it interesting that you also enjoy the xpa1010 in your system, something i found extremely fun to listen to music with, in my system.  tho, i admit, that when i switched to all-tubed gear in a 26x38 listening room, its utility was dramatically reduced, as i was getting a really nice sound from conwentional two-channel.

regards,

doug s.

[mcgsxr]

Pantera, very nice - lots of fun that is.

As for bang for the buck vehicular fun, that is why I was so passionate about building Suzuki bikes all those years.

Take one 1986 Suzuki GSXR750 (lightest one ever made).  Remove all bodywork, and passenger related equipment.  Remove 750 motor.  Install 1107 motor from 1992 GSXR1100 (most torque ever...).  Optional upgrades include suspension from the 1991 GSXR750 (inverted forks) and wheels from same (17 inch, and 5 inch wide rear to accomodate wider and stickier rubber).

Add a helmet, and complete disregard for posted speed limits.

Now hunt EVERY nice car and bike that you can find... 0-60 in around 2.7 or so, IF you are light enough, and can ride well enough - I was light enough, but did not have the lightning reflexes for those launches, so my 0-60 times at the track tended to be in and around the boring old 3 second timeframe...  Not many cars will show you a tail light even at that time.

Oh, and count on spending somewhere around $4000 US for this treat.

Nobody said it was pretty, or could carry groceries, or could attract the ladies - it was just straight up performance.  Period.

Somehow that does not mix with marriage and family... funny that!

[doug s.]

Pantera, very nice - lots of fun that is.

As for bang for the buck vehicular fun, that is why I was so passionate about building Suzuki bikes all those years.

Take one 1986 Suzuki GSXR750 (lightest one ever made).  Remove all bodywork, and passenger related equipment.  Remove 750 motor.  Install 1107 motor from 1992 GSXR1100 (most torque ever...).  Optional upgrades include suspension from the 1991 GSXR750 (inverted forks) and wheels from same (17 inch, and 5 inch wide rear to accomodate wider and sti ...

birds of a feather...  

regards,

doug s.,

'78 ducati darmah,
'95 buell s2, hot-rodded...

[Occam]

The following link has some more information about the product. Go to the link and scroll down until you see 2004_NHT_Xd_WhitePaper.pdf. .....
http://www.nhthifi.com/scripts/nhttech.cfg/php.exe/enduser/std_adp.php?p_faq ...

I found that comparison betweem your Xd and SB-3 speakers (complete with graphs!!!), as well as the non-ambiguous technical talk, particularly illuminating. Thanks.

[John Hidley]

The other speaker used in the comparison is actually an SB1, not an SB3. For some reason the version of the white paper on the website is slightly corrupted. Some fonts don't show up. I'll try to post an updated one with some more measurements.

[Occam]

SB1.... oh, even better.

[mcgsxr]

doug s wrote -

'78 ducati darmah, '95 buell s2, hot-rodded...

- "yust" gotta respect a guy with great taste in twins!

[doug s.]

doug s wrote -

'78 ducati darmah, '95 buell s2, hot-rodded...

- "yust" gotta respect a guy with great taste in twins!

thanks, mark!     i know these won't touch yer "gixxers" in outright performance, but they're so much fun, & they make such nice noises!    and, really, 0-60 in the high 3's/low 4's is plenty fast for me.   and, i don't usually wanna cruise much over 100...  

regards,

doug s.

[Occam]

The actual XdA hardware has a microphone input and USB port to allow use of the room correction software. The XdA currently ships without any software of any kind. There are four preset filters programmed into it for the XdS satellite. Each filter is designed to compensate for the XdS placed in a different environment. The four settings are 4pi (free field), 2pi (against a wall), 1pi (in a corner) and on top of a large television as a center channel.
When the room correction software is available, it will be licensed to trained installers and dealers on a per installation basis. It will not be sold with the Xd product to the consumer.

The consumer will be able to download different filter sets for the XdA from our website. We will provide optional filter sets for particular applications. For example, if you want higher output from the system, you can use two of the XdW bass modules placed very close to the XdS speakers and install a filter set that raises the crossover frequency to 180Hz. This will allow the XdS speakers to play quite a bit louder.

Currently the DEQX software only does linear corrections to the frequency and phase response. We are working on some new techniques that will allow it to do nonlinear correction. This will allow us to reduce the actual THD that the driver is producing.

The following link has some more information about the product. Go to the link and scroll down until you see 2004_NHT_Xd_WhitePaper.pdf. You can right click on this and save it or left click and open it in your browser.

http://www.nhthifi.com/scripts/nhttech.cfg/php.exe/enduser/std_adp.php?p_faq .. ...

Mr. Hidley,

A few questions -
Regarding the first graph in your WhitePaper comparing the THD (total harmonic distortion) -
1. To what extent is the the difference in THD attributable to dsp or the differences in the drivers? [Yes, we understant those benefits of the high crossover slope with regards to driver overlap. Davey has addressed this.]  How significant is the choice of these very different drivers, a polypropolene cone on the $300/pr SB1, and a magnesium cone,  distortion reducing Faraday ring, etc... on the Excel driver in the Xd system.
2. As you've cut off the THD at <3,000 hz and the curves appear to be converging, can we assume that the tweeter on the SB1 is quite good? The   descriptions for both tweeters appear quite similar.
3. The present legend on the graph descibes it as "at 10W". Should I assume this is 10 watts drive, as 10watts of acoustical output would destroy the drivers? I am used to seeing comparisons at equal SPLs(which might call for different drive level) at the same distances and preferred axis. Would you explain the possible resulting differences?

Regarding the 2nd & 3rd graphs on  that same referenced WhatePaper which compare dispersion characteristics -
4. To what extent are those characteristics, for specific frequency ranges, influenced by DSP and which is attributable to flat baffle on the SB! and and the molded baffle on the Xd?
5. The legends and descripions on all the graphs are inadvertantly obscured, and I can't discern what angles off the listening access they represent. Would you clarify?
6. Both graphs show that expected crossover off axis nulls. On the Xd I see that impressively deep null, but on the SB1 I see a shifting null. A low sloped crossover largely explains the minimal depth of the null, but the shift puzzles me.  Could you clarify and describe the crossover on the SB1? Is it similar to the Xover on your SB3, with its deliberately implemented lobing via its asymmeteric? Xover specifically engineered for its reccomended positioning and listening axis?

Your R&D efforts towards the reduction of non-linear distortions is facinating. Will this be possible with the computational capabilities on your present DEQX modules or will this have to wait for the next couple of gernerations of DSP engines? I do hope that this will not delay your efforts to deliver that room correction with conflicting resource demands.

IMO, your eventual delivery of your room correction cabability will be a tremendous upgrade. I've recently been astounded by the impact of this rather modestly demanding capability, parametric equalization(s) below 200-300hz,  can have. I'd never really realized how much room modes/nodes at low frequencies can obscure resolution at higher frequencies.

Thanks in advance.
Paul

[John Ashman]

nt

[John Hidley]

Paul,

My training of John is going better than I thought. He hit almost all of the relevant points right on:)

1) The THD difference in the first graph is entirely due to the driver choice. The Xd 5.25" motor design is responsible for about 70% of its distortion performance. The cone design is responsible for the other 30%.  

2) Yes, the tweeter in the SB1 is very good. It has almost the same distortion performance that the Xd Seas tweeter has, but the Seas unit is more consistent.

3) The THD measurements are made at a drive level of 8.94V. This is 10W into an 8ohm load. I can run the same test in a regulation mode that automatically adjusts the output level at every data point to hold the SPL exactly constant. There are two problems with this. It takes a long time. It causes the voice coil to heat up during the test. This makes the results dependant on how close the driver is to the target SPL at a particular place on the curve. Since the two 5.25" woofers in question have the same nominal sensitivity, we choose to just sweep them at a constant voltage.

4) The depth and narrowness of the notch at the crossover frequency is entirely due to the DSP high slope crossover. The smoothness of the off axis curves above 3kHz is due to the baffle design of the Xd. The relative lack of smoothness in the off axis curves in the SB1 is due to diffraction from the baffle.

5) I've posted the updated white paper on the NHT site. It has all of the legends fixed so you can read them and has a few more measurements.

6) The wide area of cancellation in the SB1 speaker is typical of passive loudspeakers. When designing the crossover, the number one priority is to get flat response on the most likely listening axis. Since the drivers each have their own varying group delay with frequency and non textbook rolloffs, this can be very challenging. This wide area of cancellation is the result of having to compromise the frequency and phase response at the exact crossover frequency with the frequency and phase response adjacant to the crossover frequency. You can use higher order filters, but in the passive world this costs more money, but more importantly it requires ridiculously high tolerance components to function.  

The nonlinear distortion reduction will work on the existing hardware. It uses some very simple techniques to achieve our goals. The room correction option doesn't add any processing overhead beyond what the XdA is already doing. The DEQX processing is already using long convolution FIR + IIR filters to do the impulse response correction. When the room correction is applied to the system, the necessary filters for the room correction are just convolved with the existing filters to correct for the drivers themselves. This results in only one set of filters being processed in the XdA for either situation.

Frequencies between 100 and 400Hz do a very good job of masking higher frequencies.

[Occam]

Mr. Hidley,

Thank you very much for the direct answers and the update of the WhitePaper. [excuse the formality, but I don't want confusions between the Johns]
Indeed, having Mr. Ashman on your team is a tremendous plus. The danger of his priaprismatic hyperbole sending certain participants into diabetic shock is far outweighed by the effect of his salesmanship on most readers.

Thanks again,
Paul

[Red Dragon Audio]

Mr. Hidley,

Thank you very much for the direct answers and the update of the WhitePaper. [excuse the formality, but I don't want confusions between the Johns]
Indeed, having Mr. Ashman on your team is a tremendous plus. The danger of his priaprismatic hyperbole sending certain participants into diabetic shock is far outweighed by the effect of his salesmanship on most readers.

Thanks again,
Paul

what does priaprismatic mean? Can't find it on dictionary.com and it's bugging me not knowing what it means... I figure over enthusiastic or something along those lines    

[Occam]

Ryan,

Sincere apologies for my wretched spelling. The word should have been 'priapismatic', from priapism - Persistent, usually painful erection of the penis,...

As the television ads say - If your erection lasts more than 4 hours, you should seek medical help immediately. Though my tendancy would be to call everyone I know and brag....