hi-res may not be necessary according to theory, however in practice modern D/A chips behave better with it (digital filtering), and as a result it sounds better.
Steve N.
Empirical Audio |
Onhwy61, yes most of the electronics today is still well below 100KHz bandwidth. Hi-end does not mean hi bandwidth; it means better sonics in the 20-20K band. It might be easier for preemie to extend to 10s of KHz above 20K but for power amps to have a power bandwidth of 100KHz will cost you very close to a 2nd mortgage. Don't believe me, do some research yourself & find out just how many power amps have a power bandwidth that even touches 50KHz. Find out what your gears' bandwidths are. Almost all audio gear was never meant to amplify ultrasonics. The Pro studio gear might be a different ball of wax. Thanx. |
Bombaywalla, Making amplifiers cutoff frequency at 20kHz means that phase shift at this frequency will be in order of 45 degree causing bad summing of harmonics. My small Rowland 102 amp has 65kHz bandwidth with about 22deg phase shift at 20kHz. New Rowland amp model 625 ($15k) has bandwidth of 350kHz. Mr. Jeff Rowland knows what he's doing (I'd like to think). As for 50kHz - a lot of power amps have -3dB bandwidth of 50kHz:
All Atmasphere amps: >100kHz
All Rowland Amps: >65kHz
All Cambridge Audio Amps: >50kHz
All Krell Amps >95kHz
All Classe Delta Series: >100kHz
All Classe CT series: >80kHz
All Luxman Amps: >100kHz
All Parasound Halo Amps >100kHz
All Parasound NewClassic Amps >50kHz
etc.
But if you won't to spend 2nd mortgage you'll find amps like:
MBL Reference 9011: 320kHz
Goldmund Mimesis 8: 800kHz +/-1dB
Soulution 710: 1MHz |
According to all the engineers and tests and specs, vinyl does not sound as good as a CD right? But so many people would prefer the sound of vinyl and/or tubes over SS amps and a CD player. So I guess all this talk about specs and cutoff freq., etc. is just a numbers thing. Will it tell you if one amp sounds better to a person than another? |
The same recording transfered to 16/44 does not sound as good as the same recording transfered to a higher resolution whether it is SACD or 24/96 (or 24/192). Can we move on and try to get recordings put out on something higher than 256k? |
Kijanki, do you know what the power bandwidth is on ARC amps, particularly the VS-115. Freq. response is approx. 100K, but I don't know if that is the same as power bandwidth. |
Kijanki thanx for that info on power amp freq bandwidth. I suppose that many more amps are higher freq bandwidth than I imagined but I don't know how many of these have the same number for power bandwidth? Any idea? |
Bombaywalla, Bifwynne - No, I don't know the numbers, but suspect it is at about a half or less. Delivering full power at high frequencies is not really important since very little power goes to tweeter. In my Rowland 102 max power at high frequencies would damage amplifier (burn out output choke). Icepower module 200ASC used in my amp is specified at 200W at 10Hz-20kHz but it is only momentary power. FTC rated power is specified as 55W but only up to 8kHz, with warning about damage to the choke at higher frequencies. It is not really important because average power when playing music is only few percent of peak power. The reason for that is that if on average music has half of peak loudness, it means 1/10 of power (logarithmic scale) and then music also has gaps (unless one listens to sinewaves). 55W of power at any frequency above 8kHz would most likely damage any tweeter, not to mention hearing. What worries me a little is 22 deg phase shift at 20kHz (-3dB bandwidth is 65kHz). It would weaken upper harmonics summing. My amp would benefit from a little more "air" but it might also be my hearing (not getting any younger) or the fact that speaker has warm character and is never bright - even on worst CDs. It has, in the system, very clean, pronounced natural sibilants. I don't want to change it and before I audition another amp (like Rowland 625) I need to fix room acoustics.
I understand Rowland's idea behind 350kHz bandwidth in model 625 - no phase shift at 20kHz and perfect step response but 1MHz bandwidth of Soulution 710 is perhaps too much. According to reviews it is excellent amplifier with very little negative feedback but in general the easiest method to improve most of amplifier's spects (like THD, IMD, DF, Bandwidth) is to use deep negative feedback that also enhances odd harmonics (overshoot in time domain caused by amps signal delay and thus late feedback summing - known as TIM) making unpleasant bright sound that SS amps are famous for. Class D has small advantage here, being practically one stage (little delay). Less than perfect design of such 1MHz amp can cause problems including instability followed by oscillations that can damage speakers or sensitivity to RFI. I would tend to agree with Audiofreek32 that numbers are not that important and often amplifier with the best spects has the worst sound. Selecting gear for audition by company reputation or designer's name makes more sense to me. |
Kijanki, u could have answered your own question about ultrasonics from 192K sampling now that you have answered the question of power bandwidths of power amps. Now you can see why a power amp would be nonlinear in the ultrasonic range & why those ultrasonic intermod distortion products folded down to the 20-20K. Now , the amplitude of these ultrasonics might not be large enough but better not to have them at all..... |
Excellent post by Kijanki. I agree completely. 04-22-12: Bifwynne
... do you know what the power bandwidth is on ARC amps, particularly the VS-115. Freq. response is approx. 100K, but I don't know if that is the same as power bandwidth. My understanding is that unless otherwise stated frequency response and bandwidth are usually specified under "small signal" conditions. I believe that for power amplifiers "small signal" is commonly defined to mean 1 watt or 2.83 volts (2.83 volts corresponds to 1 watt into 8 ohms). Full power bandwidth will sometimes be considerably less, in part because in some designs it will be limited by what is called slew rate, which isn't a factor under small signal conditions. The specifications at the ARC website do not appear to indicate either full power bandwidth or slew rate for your VS-115, so there isn't enough information to answer your question. As Kijanki indicated, though, high power levels are not required at ultrasonic frequencies, so small signal bandwidth is a more meaningful number than full power bandwidth. Returning to the question of ultrasonic intermodulation distortion, I'm not sure that bandwidth limitations are directly relevant to the issue, although they might play a role. What is relevant is non-linearity. As long as the amp's output amplitude is linearly proportional to input amplitude, at each of the frequencies for which an ultrasonic spectral component is present, there won't be a problem. Perhaps there will often be a tendency for linearity to degrade at frequencies where the amplifier's small signal frequency response is rolling off, in which case bandwidth would have some relevance to the issue. Or perhaps not; I have no particular knowledge on that question. Best regards, -- Al |
Thank you Al. If there are any harmonics within 50kHz amplifiers should be still linear (modulation can only happen on nonlinear element). Any problem would already show with vinyl gear that has similar bandwidth. I don't really see any source of audible harmonics above it. On one hand studio engineers would clean it up but on the other microphones already do it. Most of microphones go only to 30kHz and some extended response go to 50kHz. One of the most popular Neumann U87 ($3600) goes only to 20kHz while the most expensive I could find Sony C-800G ($8000) is only 18kHz. At the concerts as well as in the studio nothing goes directly - everything comes thru microphones to PA system or studio console. Further more, I suspect that studio equipment bandwidth does not extend any higher providing natural filters as well. |
Al and Kijanki, not sure this is relevant about extended bandwidth, but when I play the Four Seasons/Jersey Boys, I hear neighborhood dogs howling when Frankie Valli hits the high ones. LOL |
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To summarize....
I guess we have concluded just the opposite - that 24/192 is a VERY GOOD idea actually, as it SOUNDS GREAT and hard drive space is fairly inexpensive.
Using dbPoweramp (very cheap program) to rip your CD collection into 24/96 or 24/192 FLAC/WAV is easy to do and once the up-front work is done, you can sit back and enjoy music at least at or above the quality level of your current CD playback system all in the comfort of your listening chair.
Also, we have concluded that all the specs, tests, charts and measurements will not tell you how good a component will sound (especially how it will sound to a given person), as that is 100% personal opinion which cannot be measured at all.
Note: For what I would consider a "budget friendly" choice for a DAC solution that will play up to 24/192 files - the "Wyred 4 Sound" model DAC-2 is a very, very good piece at $1,499 and has many connection choices and built-in volume control. |
04-23-12: Audiofreak32
To summarize....
I guess we have concluded just the opposite - that 24/192 is a VERY GOOD idea actually,.... I don't know how you concluded this? I concluded that there is no need for 24/192 - 24/96 suffices as it solves the issue of steep skirt analog filter for 16/44.1 & that once this issue is resolved & we have more DR w/ 24 bits there is no real need for 24/192. |
I concluded that you are wrong... |
