Hi folks, is the so called holographic imaging with many tube amplifiers an artifact? With solid state one only hears "holographic imaging" if that is in the recording, but with many tube amps you can hear it all the time. So solid state fails in this department? Or are those tube amps not telling the truth?
Roger, I have many times had test tones being played through loudspeakers with microphones and frequency counters in use- never in the years of working in and out of the recording studio have I ever observed a connection between gain and pitch as you assert, nor have I until now, known anyone to make such an assertion. How have you measured this effect to prove or disprove your hypothesis and add what outcomes does it suggest?
I have also been able to alter the speed of the amplifier circuit (speed in this case being equal to slew rate) and again seen no measurable effect on pitch. How were you able to test your hypothesis in these conditions?
For a given change in gain, say 20 db, how much change in pitch will be measured?
So- how do you measure Doppler effect in an amplifier? What is the unit of measure? What test equipment do you use for this? How much DE is reduced by your circuit?
Guitar and synthesizer players often use a tuning device that mutes the output of the guitar so the musician can tune the instrument silently, then after that, regardless of volume, the pitch will be found to be in tune. This does not seem to matter whether there are tube or transistor amps in the signal chain.
IME again, I have found that the measurable propagation delay in an amplifier circuit does not change with the input level. How do you square this with your hypothesis? Do you have a different meaning for the word 'speed'? If so, could you define it?
Again IME by changing the volume in my system, I've never experienced a change in the soundstage perspective- that of being in the 10th row as opposed to the 2nd row for example. I would describe sound as seeming the same 'distance' away, just not as loud -certainly not a change in perspective! Does your hypothesis support exceptions or does it predict that the experience of perspective is universal?
Since when listening I am usually seated, why exactly should I care if there is Doppler effect if I move? In a real life situation, would you not also experience Doppler? It seems to me that you would want to preserve the Doppler effects of real life music. What am I missing?
"You would agree that the act of moving away from a sound source makes the frequency/pitch appear lower?"
No doubt.
I need to think about the volume knob analogy some more though since that would seem more relevant. I'm thinking Roger paul is right on this one though....
We may be entering the Twilight Zone....where's Rod Serling?
As long you like what you hear, it really doesn't matter what other people think is best.
If you think flat is more real, then more power to you.
Personally, I'd rather deceive myself into thinking I can do better since I've been given an additional dimension to play with, but then again I also like Pro Wrestling.
You missed the point entirely. If you read my post again you will see that it is not where you sit - the Doppler only occurs during the relocation process. IOW when you travel from the front of the hall to the back (walking). Once you sit down - your going to hear the same pitch as the guy in the first row but delayed by X distance.
You would agree that the act of moving away from a sound source makes the frequency/pitch appear lower?
"Not that "holographic" necessarily equates to truth either, but I can't see how "flat" could be closer to the real truth either."
Actually I can think of a way. That would be assuming "flat" refers to a projection of the original 3-D sound onto a flat plane, much as portions of the real earth are projected onto paper maps.
In this case, realize that projected representations of 3-d objects onto a map are inherently and by design distorted reproductions of the real thing.
If these "doppler" errors are indeed there, and are "microscopic" how does one determine where they occur, read them at each occuring stage, and how is their (I'm assuming) delicate effect, effectively corrected and how is that delicate(?) correction calibrated at each stage? In regard to the effect of moving the listening position in a typical listening room, I would guess that the issues of the sound changing due to the change in effect the room would have, and the issues of driver intergration might swamp the effect of such "doppler" issues.
If one says: "Wow, your amplifier sounds very holographic and 3D, far more holographic than my amplifier, which sounds a bit flat" --> then this mean that the holographic sounding amplifier sucks? Sometimes I'm confused about this issue. If "holographic" or "3D" sound is an artifact, then an amplifier should sound "flat", because that is closer to the truth (and the truth is far more "flat" than many audiophiles are accustomed to)?
>> 09-25-08: Atmasphere Tbg, sorry, but, **there is no doppler effect in an amplifier**! If a designer of a 'holographic processor' tells you something like that, turn around and run as hard as you can!
Atmasphere, with all due respect.
I know I have mentioned this until I'm blue in the face - but here it goes again for clarity.
A - There IS Doppler in amplifiers - just not to the best of your knowledge.
B - H-CAT is not a processer,generator,gimmick, or something that "alters" the original recording and therefore creates distortion. It on the other hand is the only method of amplifying that deals with the real problem of where distortion comes from. Doppler distortion is the SEED of harmonic distortion. Harmonic distortion is the result of Doppler distortion that has been allowed to get out of control. If you can detect and correct Doppler errors in real time - you cannot generate harmonics.
I owned a Hitachi Class G receiver once back in the 70's when I lived in a dorm and wanted high power in a small package. It had some good attributes but for whatever its worth I would say low distortion and holography were not this piece's strength compared to most every other piece I have ever owned..
Sounds like a common theme is low distortion is good for holography and each company/designer has their own ways of dealing with the distortions they care about most.
Each approach has up and downsides. Which is best? Who knows and who cares.
If your getting good "holography" on your system, then whoever designed your amp is probably doing a good job of dealing with distortion in a manner that delivers positive results effectly.
Nothing new here. There is seldom ever a single approach to anything that has all the benefits and none of the disadvantages. So I wouldn't lose any sleep wondering who does it best. Just listen and judge for oneself...what else is needed?
The Doppler effect in amplifiers is not actually a different problem than the one "solved" by NFB. It is the root of the problem that NFB cannot fix by design.
NFB is a servo system that only works for steady state sine waves. Not for complex music.
Even if you use massive amounts of NFB - you cannot remove Doppler. It is the wrong tool.
Is doppler effect in an amp a different problem than the one solved by application of negative feedback? If so, how much is it different in terms of the effect on the sound?
Thank you for understanding at least part of the science behind Doppler interference in an audio system. Of course none of the above is "moving" (ignoring the speaker cones for now). However, the electronics used to amplify the audio signal can alter the speed and therefore the pitch of what you hear. Since the effect is based on the relative distance between the sound object and the observer - it is not necessary to move any of the sound objects - just the observer. You and your system are the observer. Now since I don't expect that you are moving toward or away from your speakers, that leaves the delivery speed of your system.
Once you accept the fact that you can alter the speed of your system electronically and therefore emulate the physically induced Doppler effect - then everything will fall into place.
How can you induce Doppler electronically? The easiest way is to do this is by adjusting the playback speed on a tape deck while you are listening to music. An increase in playback speed (velocity) will cause an increase in pitch.
Moving toward a sound object PHYSICALLY will do the same thing. So you can see that it is possible to cause an effect (electronically) that we normally associate with the physical world.
I know your saying to yourself "but I'm not listening to a tape deck with poor speed control - I'm listening to my very stable digital front end."
Here is the problem – the analog amplifier circuitry in your system contains very small variations in speed (velocity) as the audio signal travels through your entire system and exits via you speakers. How can you change the speed of a signal as it is being amplified? All you need to do is alter the gain by a tiny amount and you have altered the speed.
Take for example you are listening to a recording of a live concert. You adjust your volume control for a “normal” listing level. You feel like you are in about the 10th row back. Now you decide to turn up the volume and you feel like you are in the front row (closer). If you then turn down the volume much lower so you feel like you are 20 rows back.
By adjusting the gain of your system – you have zoomed in and out of the scene. You have electronically moved the stage closer and farther away from you. Now, here is the most important aspect of this example to grasp – what I described was an action taken by you in your living room (setting the volume) to simulate the 3 relative listening positions at the concert hall. Now picture the actual physical repeat of this example. In other words you ARE at the concert hall. You are sitting in the 10th row and listening to real musicians play through the medium of air. There is no change in pitch / no Doppler. Now you get up and walk toward the stage to sit down in the front row. Again you listen from the front row (louder) but again with no change in pitch / Doppler. Everything seems normal and stable so what is the point?
Here is what you missed. It is not the location you listen from that changes the pitch. It is the movement you made between the locations that introduced Doppler. In other words when you walked toward the stage – the pitch of all the instruments was increased. If you were to walk toward the back of the hall to sit in row 20 you would experience the lowering of the total pitch of the music.
To tie this into what happens in your living room – the act of walking toward the stage IS the same as you turning up you volume (as it is being adjusted). Once you stop adjusting the volume – you are again stable and free from Doppler.
In case you think this is BS – here is a way to prove it in you own system.
Get a reference CD of pure tones and select a 1Khz tone to play in your system. Set you volume control to some “medium” level. Now turn the manual volume control up and down rapidly (wiggle).
What do you hear? Besides the obvious change in loudness – yes the FREQUENCY goes up and down. Your 1000 hertz tone can drift up to 1100 hertz and down to 900 hertz depending on the speed and depth of the physical changes to your volume control. (Turning it up and down slowly will give almost no perceived change in pitch)
How is it possible to alter the frequency just by changing the gain? It is because the gain represents the efficiency of the delivery system and is directly related to the velocity of the traveling signal. Increasing the gain will accelerate the velocity and decreasing the gain will de-accelerate the velocity.
This all boils down to the involuntary changes in gain that occur in your system when you are not making adjustments (yourself). These microscopic changes in gain happen all the time while you are listening and your brain translates (correctly) that the relative distance between you and the sound objects is drifting and unstable. This wobbling distance is actual Doppler. As a result your “scene” is out of focus and bloated. This produces harmonic distortion on a scale that is far below the radar of all modern test equipment. However your brain has no problem picking up on this effect. It immediately recognizes that “this is not real”. In order to convince the brain that “this is real” – you most stop the Doppler effect from happening during the amplifying process.
BTW – the natural side effect of stopping the Doppler is holographic imaging.
I haven't heard the H-Cat gear. I am dubious of these claims. How does one determine just where in the circuit these errors occur? Does the circuit allow for the approporiate correction to be applied in each instance of error, and is that necessary? If in fact these errors are in evidence, wouldn't a (with prejudice aside) digital input read compared to a digital output read and correction make more sense?
Tbg, sorry, but, **there is no doppler effect in an amplifier**! If a designer of a 'holographic processor' tells you something like that, turn around and run as hard as you can!
You have propagation delay in any amplifier circuit but that does not create doppler effect, in either an amplifier or a preamp. It is possible to get some in a loudspeaker driver that has wide range and high excursion, but that can be dealt with by proper speaker design. IOW, if 'doppler effect' is really the reason, its at best a fix for a problem that does not exist. At worst--? Certainly such a 'process' can be considered a distortion in the overall output...
I get the feeling that a lot of these holography systems that have appeared over the years are aimed at those who have a lack of resolution in their systems- and can stand listening to an effect, rather than the music.
FWIW: It is easy to add holographic effects or wide soundstage by using a flanger or adjusting phase between two channels - guitar folks know this all to well - there are literally hundreds of sound effects. Another effect is reverb circuitry like Harmonix
There is a science behind these effects too but it is too much to go into here. I share Ralph's opinion though - I prefer not to add extra effects to the CD's I play - even if some of it on some tracks can be pleasing addition/change.
" the so called holographic imaging with many tube amplifiers an artifact? With solid state one only hears "holographic imaging" if that is in the recording, but with many tube amps you can hear it all the time. So solid state fails in this department? Or are those tube amps not telling the truth?"
It is not artifact. On the contrary. In Spectron stereo there is good 3D representation. In fully balanced monoblock mode where distortions are almost zero, every owner and every reviewer report uncanny holographic imaging.
Doppler effect ? What is moving ? Were the instruments and musicians on wheels during the recording or were the mikes? Of is it during the playback - I picture speakers on motorized wheels careening first toward the listener and then shifting into reverse.
Atmasphere, the Doppler shift is not in the recording it is in the electronics that you are using to recreate it.
The WTC afforded matching the H-Cat P12R line stage with other electronics. Frankly I wish it were auto-focusing like second generation cameras, but like cameras this is not to say that the properly focus image is not worth it.
Theaudiotweak, arguing with Audiofool is like conversing with an epileptic in a seizure.
There was a tube amp some years back that had a front panel selector to adjust the amount of negative feedback.Click..click click. The reviewer a friend and co worker of mine felt that the 6db selction point of feedback was to his preference. His thoughts were that his choice was a combination of texture, speed and detail. Zero feedback was to fat and slow to much feedback was thin and slightly bright. I have not heard the H-Cat..but negative feedback is not in the brew here. Tom
I agree with the merits of fessing up to a mistake, but given the apparent severity in this particular case, what other option is there?
At least it sounds like it has a chance to work now if adjusted properly.
I guess the only way to know would be to listen and compare.
Still not sure though how this is better in practice than negative feedback? Sounds like a tricky proposition to get right, certainly harder than providing an adjustment.
Amazing that an ego attached to a design such as the original H-Cat would attest to a possible flaw and then decide to publish a fix. I think thats great! Live and learn and learn a whole lot more. So many designers and manufacturers never fess up to their mis calculations in design or production. I think this is a progressive reality of the ongoing design process and not a flaw but a tribute to the designer/builder. Tom
I don't know for sure whether the H Cat does what it claims or not since I've never heard.
But my understanding from their web site is that they sold early models of a device that requires adjustment to work right without any way to perform the needed adjustment.
Doppler effect??! I would think that if there is any doppler effect in the recording, you would certainly **not** want to compensate for it. Otherwise you would not be playing it back right :)
I get the feeling that a lot of these holography systems that have appeared over the years are aimed at those who have a lack of resolution in their systems- and can stand listening to an effect, rather than the music.
Sorry for the criticism, but I've always felt bad for people who've laid out the cash over the years for such things. IMO/IME the best performance in the audio system will be when there are as few processors/audio building blocks between the recording microphones and the playback speakers as possible.
I carry "memories" of live music, and still attend performances from time to time (but recently I hardly ever get the time) but I tend not to use live music as a benchmark except for some classical music - specifically chamber music. For me, there are very few times when I have been able to get the seat at the venue I would have needed to get in order to achieve the sound I can get at home. In addition, a lot of performances are amplified and the music sent out over speakers and the music competes with the girl next to me shouting to her boyfriend how TOOOOHHHHTALLY AWESOME the whole thing is, the guy in front puking his guts out, and the person behind me spilling beer he smuggled in. So much for rock concerts.
Jazz is OK, but jazz and classical concerts for me are so much more about appreciating an interpretation of music you already know. There are, as Detlof knows, umpteen versions of the Goldberg variations, and I'd swear I can hum along with the best of them and not get a note wrong, but I can still be surprised by little things when I hear a performance, and it is the interpretation, NOT the sound, that I seek when I go out of my way to listen to live music. And THAT benchmark is tough to emulate at home.
My personal 'benchmark' for my system is more an 'image' of what that particular performance SHOULD sound like. It may not be a memory per se; instead it may be an image created in my head, a mishmash (partly based on memory) of knowing what a given musician should be able to do with a given piece of music and a given group of people, along with the instruments, the temperature, whether it was the first take or the 5th, and trying to figure out whether the conductor or ensemble really was satisfied with what they did. Indeed, the chance to actually compare live with 'memorex' is indeed very small, but that doesn't bother me in the slightest - the live performances I appreciate the most are the ones which would lose their charm if repeated anyway.
Tbg, Thank you for your detailed response. Seems, that you - like me -carry an idea, a "memory" if you like, in you what "real" music sounds like and use it as a benchmark in critical listening of your rig. The chance to get direct comparisons between a specific live event in a specific venue with a take of that very event through your rig at home is indeed very small.
I take great pleasure in hearing and speaking about concepts and tweaks that cost only a few dollars and make more fundamental difference in sound quality than what a blowviating dealer may offer for thousands and is obsolete in weeks or months. Tom
Detlof, I have been to many concert presentations at the University auditorium which is useless unless you sit in the first two rows center. It is an electronic reverb hall and is awful. I have been is several symphonic halls but have no recordings from any. I did some recordings of big jazz presentations at Florida State Un. and was there, of course. I no longer have a tape machine, but do have recordings of the North Texas Jazz band and was present at one of these. Here I did hear actually better presentation than I heard from my left side seat.
I have also heard many small group un-amplified sessions and have many near-field records done in such a configuration.
What I am talking about, however, is a very precise location on the sound stage both left and right but also in depth. Plus a very sharp leading edge that startles you as is the case in real-life. Plus a top end that shimmers, especially on high-hat and brass bites. Finally, the speakers are gone and you are enveloped in the sound stage.
What Feil is ragging on about in his characteristic way is that the secret of the H-Cat circuit is a Doppler correction that keeps all frequencies emerging at the same speed.
Bill, I'm bald, which now that you've said it, might interfere with the soundstage, sometimes even mimicking holography. What would you suggest? should I buy a wig? Worried and waiting for expert advice.......
You write in your post: "I had excellent imaging and close to realism." Could you please expound what you mean by the term "realism". Are you reminded of what you remember to have heard on several occasions at live events with similar kinds of music or do you have a sort of fixed engram in you what live music of any kind in any given venue would sound like?
Have you ever, being familiar with a concert venue and having heard music there, compared exactly the same music, recorded at the same venue, with what you heard at home with exactly that recording?
Tvad, you know from our previous exchanges that I have used tube traps, RPG diffusors, Room Lens, acoustic mirrors, LEDE, and Holographs, one pair of which I still use. I have tried digital corrections also. I have had tube traps. I have used Combac and Marigold dots on the walls, I have used MD Brilliant Pebbles, Shun Mook Mpingo disks, and recently Acoustic Revive guartz products. Once I even had the Cello analog equalizer. The rug never proved very important for the good or bad. You knew all of this so why did you post?
I've heard Ohm CLSs outdoors and they sound best, very close to lifelike, with just a single wall behind them. They also tend to like larger rooms in order to have sufficient "room to breathe".
True omni's should not be placed close to walls from what I hear.
One advantage of the Ohm pseudo-omni design (for two channel stereo systems they are physically attenuated with sound absorbent material inside the "cage" in the wall facing directions as I believe you know) is that they can be placed within 2-3 feet of walls where they tend to sound much like more conventional box speakers with very wide dispersion and the huge soundstage.
I know no one believes me but the electronics play a greater role in imaging than any of you or I believed. If you get a chance to hear the H-Cat amp, perhaps at the RMAF, you will know what I mean. I thought with my careful set up, speaker placement, vibration control, and room treatments in an already good sounding room that I had excellent imaging and close to realism. I won't say that I have absolute realism now, but I was only about half way before.
Though it might be an anthema to those who fancy omni-directional (or those trying to aproximate that goal) speakers, I can't help but wonder what omni's might sound like in a heavily treated room that would mitigate the surrounding reflections.
I agree with Detlof but I'd like to add that once ones equipment and the recorded music and room is capable of the holographic image, speaker placement is paramount.
I have an absolutely beautiful 3-d sonic hologram image with my electrostics. When my housekeeper just nudges them ever so slightly (i'm talking 1/4 inch...), that image is grossly effected.
Yes, it is the recording, the rig, the room, the speakers, their placement, state of the power, even the weather and last not least our ears and what is between them. Which does what is devilishly difficult to pinpoint and the more experienced you are the more unsure you become. Just like real life, ain't it? (:
" I have found that putting sound out in front of the plane of the speakers is more related to speaker design (I have only experienced this phenom with a horn/cone hybrid and it a general soundfield attached to most recordings. But it was fascinating especially with that old Carver 9 holograpy machine in the loop). "
I have heard it to a huge extent recently in a dealer showroom using Krell 400xi integrated driving either Martin Logan electrostats or Focal dynamic/cone designs. Which speaker made little difference.
I think it had something to do largely with room acoustics as well, in other words, the portion of the room behind and to the sides of me was "hot" or very lively in relation to the area behind the speaks.
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