These two sites gave the highest ratings to the Naxos production of the Shostakovich 10th Symphony in 2011 (V. Petrenko & Liverpool Philharmonics). I bought the CD, did not like the sound, and subsequently found out that the recording is clipped at quite a number of places.Whilst being 'subjective' I found a couple of reviews of it. Reading them you really wouldn't think they were reviewing the same piece
TCHAIKOVSKY Symphony No 6. Romeo and Juliet | gramophone.co.uk
Good, Not Great Tchaikovsky From Bychkov - Classics Today
Gramophone even awarded the Orchestral of the Year 2011 prize to the recording! Here is a quote from the review:
"With the possible exception of the brass balance, noted above, the Naxos recording is clear and full-bodied."
A record I dare recommend for the dynamics is the Grieg & Liszt Piano Concertos by S. Hough (Bergen Philharmonic, A. Litton) on Hyperion.
The polar diagram in the MusicScope analysis report of the 1st Movt. of the Liszt shows a dynamic range of some 50dB (difference between the lowest RMS value (orange) and the highest peak value (green), the angle being the time axis). I've got it in a HD version, downloadable from the Hyperion web site; a CD version is also available.
Regards,
Braca
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Chris, if your system has for instance 0.1% THD, meaning that frequencies not in the input signal are created 1/1000 the strength of the signal, I can imagine that the resonance of the heatsink fins, might also reach 1/1000 of the sound from the speaker and thus be audible. Reasonable?
In a world where 0.001% cap distortion is thought to be audible, surely mechanically vibrating heatsink fins would be audible??
Jan
DNi I have quite a lot of Hyperion recordings, but that one is not in my collection, I will look it out. They are swines as they produce long running series of often first recordings to keep you hooked (Romantic piano concertos is up to volume 73). BIS are also bad at that, but I couldn't stretch to their complete sibelius set last year.
It is a good time to be a music lover
It is a good time to be a music lover
Hi Jan,
I'm pretty sure the amplitude of the mechanical noise is lower than 1/1000 of the audio from the speaker system. I have difficulty hearing it over the ambient noise sometimes. Cheap amplifiers often have ceramic capacitors that are louder than a heat sink would be, just to add some perspective. I don't think that any mechanical aspect of the amplifier would be noticed. In fact, speaker cabinet vibrations, and vibrations in the listening environment would swamp anything coming from the amplifier.
This is more a curiosity detectable with special circumstances. Running an amplifier to higher power levels while connected to a dummy load is pretty much a service bench specific situation. A nonissue when you consider all the other sources of vibration and distortion.
-Chris
I'm pretty sure the amplitude of the mechanical noise is lower than 1/1000 of the audio from the speaker system. I have difficulty hearing it over the ambient noise sometimes. Cheap amplifiers often have ceramic capacitors that are louder than a heat sink would be, just to add some perspective. I don't think that any mechanical aspect of the amplifier would be noticed. In fact, speaker cabinet vibrations, and vibrations in the listening environment would swamp anything coming from the amplifier.
This is more a curiosity detectable with special circumstances. Running an amplifier to higher power levels while connected to a dummy load is pretty much a service bench specific situation. A nonissue when you consider all the other sources of vibration and distortion.
-Chris
Indeed, Jan. But if you consider this acoustic parasitic sound is not part of the electrical signal itself, do not create artifacts in it, like IM or harmonic distortion, and that our hearing system is pretty good to isolate sources from different locations, I believe, like anatech, that the impact will be a lot less important.
Think of two musicians, playing the same melody with different instruments. Easy to isolate each. or your wife, whispering the melody at yourr left.
Reasonable?
Anyway, if you worry about this, as you said: it is easy to find "working solutions".
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What probably happened is that leakage current put dc on the case/earth connection of your audio system. High voltage, but high impedance and AC. However, all grounds are low impedance and DC to boot, so by the time you feel a shock through earth potential differences, in all likelihood your heart will stop beating.
Btw, Dutch cable does FM radio, I thought that was pretty much standard. Quite analogue, for listening, that is.
It has been about 12 years since I was first asked for this 'schematic' that started this thread. Of course the reason for all this has been lost in time and squabble. '-) But here it is. I have left out the servos and the power supply buffers, do your own thing! (PS, I stole the original circuit from Charles Hansen so blame him, not me.)
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Hi, vacuphile,
As far as I know, The cable, in my country only provide digital TV, digital radios and Internet, no analog in it.
Anyway, FM is a an analog signal, yes, but it is just a modulated frequency at constant level. If the cap is chosen to be large enough to pass those frequencies, i doubt any evil on the demodulated content. The bandwidth of the modulation is very thin, in regard to the frequency of the "porteuse" (Radio carrier ?)
Not sure of the word in English, I apologize.
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Chris (and Tryphon), what worries me with these things is that it is very narrow-banded. You sweep the signal frequency, hear nothing until you hit the mech res freq and it takes off, relatively loud. But I admit I never did any real measurements. Ears-only and we all know how unreliable that is ;-)
So maybe I worry unnecessarily...
Jan
Jan, I was pulling your leg when I suggested
I have encountered the issue many times in the past with amplifiers on the bench.
In the past I also broached the subject and was similarly met with ridicule from the usuals.
Sweeping sine will find particular resonances, running rock music into a dummy load will excite a whole bunch of sounds out of the heatsinks, and clipping makes the effect much louder acoustically.
The HS fin resonances are slow to decay so will contribute to 'in room sound' and reduction of 'silence between notes'.
This problem is recognised by some audio manufacturers whose solution is to fit rubber wedges between the fins, just like motorcycle engines with rubber wedges to quench cylinder head/barrel fins resonances.
On this subject of spurious acoustic sources, I venture that the natural sound of a phono stylus 'adds' to the experience, and is undesirable.
Listening to the acoustic sound of a stylus tells much about how it performs when amplified and reproduced.
Dan.
Oh, I don't think so. it is interesting, anyway. Each detail matter, when you look for the best, and each question we ask for ourselves can be productive.
There is one thing that seems obvious to me: if there is a noise produced by the amp, it means that an energy is stolen somewhere, at least in the power supply. It implies more work for the feedback, or more distortion if no feedback loop, don't you think ?
This said, this energy can be, anyway, dissipated in heat, so, I am probably stupid, saying this (more a question than anything else) ;-)
On the acoustic point of view, it is not so difficult, to cure most of the issue, with trasfos where wires are strongly glued, and with radiators acoustically dumped.
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Yes.
Yes.
In my experimentations, I find that heatsinks are not entirely benign.
Coatings and other formulations applied to heatsinks can change the overall sound of the amp, go figure.
Dan.
That's an interesting viewpoint. You could also say that any distortion involves extraction or insertion of energy not normally in the signal.
It puts me to think because I am just now looking at a MOSFET driven at the source (common gate). It is generally considered that this is low distortion because there is no gate current so the output current at the drain is pretty much the same as the driving current at the source so low distortion.
But in my case, a high-voltage VAS, the drain current is very low like 5mA, and in that situation the gate current, charging/discharging the parasitic capacitances, is a sizeable fraction of Id thus causing distortion. Energy lost.
If you measure Igate and sink the same current from the source, you compensate by inserting energy at the source that is lost at the gate.
Jan
Hi Jan,
These resonances are not excited by a continuous tone, so they won't build up to some maximal output Not unless you listen to a "sine wave symphony". Kidding here.
The rubber wedges sound like an interesting approach that would be very effective I would think. But I think a test would be in order before deciding on a course of action. Remember too, there are many components that would output noise at higher levels. Maybe a touch of silicone on these parts would damp them enough?
So, the test. Move the amplifier out of the room and hopefully around a corner. Then listen to some music with high crest factor passages. This should be a repeat of what you had done with the amplifier (with extended leads) in the room. You can repeat the test with friends and reach some consensus first. It is possible that you may discover that rather than treat the amplifier, you decide it has to be mounted in another room or downstairs. At least you will have learned something and can decide on the strength of knowledge. Of course, you also may find that the concerns are not important enough to warrant any action on your part. I would be interested in what you find. Your amplifier is likely silent from the look of the PAX. If not, you have intimate knowledge of the amp and can design a silicone party if need be.
Best, Chris
These resonances are not excited by a continuous tone, so they won't build up to some maximal output Not unless you listen to a "sine wave symphony".
Kidding here.The rubber wedges sound like an interesting approach that would be very effective I would think. But I think a test would be in order before deciding on a course of action. Remember too, there are many components that would output noise at higher levels. Maybe a touch of silicone on these parts would damp them enough?
So, the test. Move the amplifier out of the room and hopefully around a corner. Then listen to some music with high crest factor passages. This should be a repeat of what you had done with the amplifier (with extended leads) in the room. You can repeat the test with friends and reach some consensus first. It is possible that you may discover that rather than treat the amplifier, you decide it has to be mounted in another room or downstairs. At least you will have learned something and can decide on the strength of knowledge. Of course, you also may find that the concerns are not important enough to warrant any action on your part. I would be interested in what you find. Your amplifier is likely silent from the look of the PAX. If not, you have intimate knowledge of the amp and can design a silicone party if need be.
Best, Chris
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