For what it is worth......
Some years ago I bought a pair of crude, home made speakers that turned out to contain an old but nice pair of Tannoy12 inch Monitor golds.
They were complete with the separate enclosed crossover with the old 'Roll Off' and 'Energy' controls. At this point the units had beem removed from the cabinets and were 'naked' on the workbench for testing. After testing I played some music through the units and noticed that the crossover box was rattling a bit on the bench.
For some reason I unplugged the 4 way connector from the crossover to the the drive unit and played the music again, the crossover was very clearly rattling an buzzing along with the music, in fact so loud and clear that you could easily tell what the song was and sing along.
In this case we are looking at the crossover as a transducer, electrical to mechanical in this instance, given the nature of transducers I would not be at all surprised if the crossover box worked in reverse, ie was microphonic.
Some years ago I bought a pair of crude, home made speakers that turned out to contain an old but nice pair of Tannoy12 inch Monitor golds.
They were complete with the separate enclosed crossover with the old 'Roll Off' and 'Energy' controls. At this point the units had beem removed from the cabinets and were 'naked' on the workbench for testing. After testing I played some music through the units and noticed that the crossover box was rattling a bit on the bench.
For some reason I unplugged the 4 way connector from the crossover to the the drive unit and played the music again, the crossover was very clearly rattling an buzzing along with the music, in fact so loud and clear that you could easily tell what the song was and sing along.
In this case we are looking at the crossover as a transducer, electrical to mechanical in this instance, given the nature of transducers I would not be at all surprised if the crossover box worked in reverse, ie was microphonic.
Jota180
Well-known member
davedotco said:
It's to give the older people the comfort blanket of the sound they grew up with and are used to. It's arguable as to whether deliberately lowering the fidelity to give something the 'analogue sound' is 'hifi' or not.
Covenanter
Well-known member
davedotco said:
I'm not wholly surprised that a crossover unit might be microphonic although the extent of the effect you describe is somewhat extreme (I'm not doubting it!). Inductors are easily affected by vibrations (just simply be varying the distance between the coils) and some capacitors can also be (either because the distance between the plates might change or because the materials may have peizo-electric properties) and put those things close to a generator of vibrations like a loudspeaker and you are likely to get some effect. How large that effect might be I do not know but I would have thought that loudspeaker designers would take it into account.
I am much more sceptical about the effect on components inside a device which is physically separate from the source of the vibration.
Chris
Jota180 said:
You are not quite getting it. The music on in the file remains unchanged, it is still the same digital recording.
All that happens is that a little noise is added, the noise level is pretty low, around the edge of audibility. Some people did not hear the noise but prefered the file with the added noise (that they did not hear), which they considered to be 'more analogue'.
The fidelity of the recording is not changed in any way, the noise floor is just raised a little that is all.
Interesting theory by Bob Carver about the "magic" behind tube amps.
Home Theater Geeks 29: Audio Legend Bob Carver
People love loudness but also reverbination in acoustics. It makes things bit more realistic to us, more ambiental.
Home Theater Geeks 29: Audio Legend Bob Carver
People love loudness but also reverbination in acoustics. It makes things bit more realistic to us, more ambiental.
Interesting read about voltage matching between amps and how it influences on amps sonic character. Example a Naim is a Class B high gain pre-to-power and Exposure is Class AB passive attenuator making all the gain in the power amp stage. They sound different even with similar power output specs.
/quote/
So if too little gain is a problem, we should flock to amplifiers with higher than average gain, right?
Not so fast! A very high level of gain leads to its own problem, namely noise. It makes sense when you think about it: in the previous scenario, our AVR was being asked to put out a lot of output, whereas now it is being asked to deliver relatively little voltage. As the voltage from our preamplifier output goes down, our signal will get ever closer to the noise floor of the system. Get too close, which is more likely with a higher sensitivity speaker, given that they need less output from the amplifier to begin with, and you’ll quickly learn the meaning of the saying “garbage in = garbage out”.
Besides noise configuration, an increase in amplifier gain will decrease in the bandwidth (BW) of the circuit, meaning some valuable data may get eliminated from the input signal (the amplifier works as a filter). Additionally, having a high gain amplifier may introduce DC offset at the output. In an amplifier with high input impedance, increasing the gain will introduce a DC offset which affects the operating point of the circuit (changes the balance of the amplifier).
/source/
Amplifier Voltage Gain Explained – Matching Amp to Preamp
/quote/
So if too little gain is a problem, we should flock to amplifiers with higher than average gain, right?
Not so fast! A very high level of gain leads to its own problem, namely noise. It makes sense when you think about it: in the previous scenario, our AVR was being asked to put out a lot of output, whereas now it is being asked to deliver relatively little voltage. As the voltage from our preamplifier output goes down, our signal will get ever closer to the noise floor of the system. Get too close, which is more likely with a higher sensitivity speaker, given that they need less output from the amplifier to begin with, and you’ll quickly learn the meaning of the saying “garbage in = garbage out”.
Besides noise configuration, an increase in amplifier gain will decrease in the bandwidth (BW) of the circuit, meaning some valuable data may get eliminated from the input signal (the amplifier works as a filter). Additionally, having a high gain amplifier may introduce DC offset at the output. In an amplifier with high input impedance, increasing the gain will introduce a DC offset which affects the operating point of the circuit (changes the balance of the amplifier).
/source/
Amplifier Voltage Gain Explained – Matching Amp to Preamp
Vladimir said:
To be honest Vlad, the above article is over complicating the issue.
If you choose pre-amp output level and power amp input level that are in a sensible range and not a hopeless mismatch you will be fine. In any case it will be pretty obvious from the volume setting on the pre-amp if you have a real problem.
Any reasonably experienced enthusiast will match levels and gain almost without thinking, it really is not that difficult.
Indeed. However, in this topic we are deconstructing which elements in hi-fi components give them their overal sonic character. People want to know why tubes sound different, why naim sounds different or arcam or mosfet or class D etc. All part of the hobby, curiosity on how our toys work.
Vladimir said:
Technically I have no real idea how components work, I kind of understand how some aspects of the design will alter the sonic character but I think, assuming an overall competent design, the voicing is pretty much down to the designer.
I have owned and used a fair amount of ARC product over the years and they use all valve, hybrid and solid state designs seemingly as the mood takes them. Irrespective of the technology, there is a fair consistency of character across the range, I once demo'd a Classic 120, all valve against my solid state D400-2, the Classic was a little more 'see through', the D400-2 had a little more 'presence' but the differences were smaller than you might imagine.
A well made valve amp and a well made solid state amp will both sound (amplify) the same if used within their operational levels without clipping. It is when tube amps start clipping in large dynamic transients (basssss) when they begin clipping but unlike SS amps with a pleasant distortion.
Only audible difference would be the low damping factor in tube amps making them reactive to speaker impedance changes. Same thing happens with Naims, its what makes them "musical". Also the bass gets a bit flabby but many don't mind, even prefer it with instrumental music.
Tubes like volts but hate amperes and thats the whole secret really. You can't chuck out as many amperes as a BJT or MOSFET amp would to maintain voltage when loudspeaker drops impedance (V=IR). Tubes are beautifully linear for preamp use (many say better than SS) but outdated for power amps. An ARC hybrid preamp using FET and valve is a superior solution.
Only audible difference would be the low damping factor in tube amps making them reactive to speaker impedance changes. Same thing happens with Naims, its what makes them "musical". Also the bass gets a bit flabby but many don't mind, even prefer it with instrumental music.
Tubes like volts but hate amperes and thats the whole secret really. You can't chuck out as many amperes as a BJT or MOSFET amp would to maintain voltage when loudspeaker drops impedance (V=IR). Tubes are beautifully linear for preamp use (many say better than SS) but outdated for power amps. An ARC hybrid preamp using FET and valve is a superior solution.
Vladimir said:
A long time ago Peter Walker of Quad, set up a blind test comparing the companies three power amps, The valve Quad II, the class AB Quad 303 and the current dumping Quad 405.
I believe a high quality studio tape was used and the speakers were Quad ESL57. Lots of jounalists and industry figures tried the test and none could tell which amp was which, and that was the best part of 40 years ago.....!
chebby
Well-known member
Glad to know that you were there.
This was a comparative demonstration of power amplifiers used under circumstances that allowed each amplifier to work within it's capabilities. As such it was a serious attempt at showing what does and does not make a real difference in the reproduction of music.
As such it made no attempt to engage the listeners preferences or predujices, just a simple question of whether the type of amplifier is important or not. In this case it showed that any differences are most likely to caused by other factors, ie 'voicing'.
Bob Carver proved the qualitive aspects of this kind of demonstration a few years later, by tweaking his own modestly priced solid state amplifier to sound indistinquishable from a multi thousand pound 'state of the art' valve amplifier.
This was a comparative demonstration of power amplifiers used under circumstances that allowed each amplifier to work within it's capabilities. As such it was a serious attempt at showing what does and does not make a real difference in the reproduction of music.
As such it made no attempt to engage the listeners preferences or predujices, just a simple question of whether the type of amplifier is important or not. In this case it showed that any differences are most likely to caused by other factors, ie 'voicing'.
Bob Carver proved the qualitive aspects of this kind of demonstration a few years later, by tweaking his own modestly priced solid state amplifier to sound indistinquishable from a multi thousand pound 'state of the art' valve amplifier.
davedotco said:
I have never made a serious adition of power amps, and maybe because of that I am missing the point.
Do you think that the reason that they were not able to tell one amp apart from the other was because the three were from the same vendor—i.e., similarly voiced? Or just because it is difficult to tell apart similarly specified amps?
Vladimir said:
There were actually two challenges.
The best documented was the Stereophile challenge where a Conrad Johnson Premier 5 valve power amplifier was used. The Audio Critic magazine used the Levinson.
Bob Carver actually won the challenges in both cases.
unsleepable said:
Firstly the amplifiers were not 'similarly specified'.
If measured in the modern manner, with distortion held below 0.1%, into an 8ohm load, the Quad II would be about 8wpc, the 303 about 28wpc and the 405 approaching 100wpc, so very different.
The famous Stereo Review blind test showed just how similar amplifiers could sound in certain circumstances and these were from different manufacturers. In my experience any substantial differences that are heard are either deliberate 'voicing' on the part of the designer or functions of the amplifier/loudspeaker interface.
davedotco said:
This seems to go in the line of what I was asking in another thread… Voicing (or sound signature) is clearly distinguishable in a preamp—when there is one, anyways—, and my doubt is whether it happens the same in power amps.
So according to this, the (probably oversimplified) conclusion could be that specs like power and damping are for a power amp more important than voicing. Is it that?
/quote/
Veteran reviewer Julian Hirsch of Stereo Review tackled the subject of amplifier sound in an article in the 1980’s. Hirsch was a meticulous reviewer, a formally-trained engineer who put his faith in rigorous, repeatable, scientifically-valid tests and procedures. He completely eschewed imprecise fads like green Magic Markers, Shun Mook M’pingo discs, and $1000/ft interconnects that had no discernable or measurable differences compared to standard cables.
After exhaustive testing of several amplifiers with several different speakers (some known to be “easy” loads and some known to be “difficult” to drive), Hirsch made some interesting observations that simultaneously explained why there were potential sound differences between amplifiers while at the same time remaining utterly faithful to the quantifiable, repeatable scientific process. It remains, in my view, the best explanation for this entire topic that I have yet seen.
Starting with the huge and all-important assumption that the amplifier under test is not being driven into distortion or being operated in a way that could elicit bad behavior, overheating, or engage any protection circuitry, Hirsch found the following:
Some pre-amp/power amplifier/speaker systems combined in such a way as to produce a very slightly rising or drooping frequency response across the entire 20-20 kHz audible spectrum. It could be a combination of the way the pre-amp and power amp combined on an input/output impedance basis, it could be because of the way a particular amp behaved with the specific load presented by that specific make/model of speaker, but there were system combinations where the frequency response showed a variation across the band.
/source/
Audioholics - The Loudspeaker & Amplifier Interface
Veteran reviewer Julian Hirsch of Stereo Review tackled the subject of amplifier sound in an article in the 1980’s. Hirsch was a meticulous reviewer, a formally-trained engineer who put his faith in rigorous, repeatable, scientifically-valid tests and procedures. He completely eschewed imprecise fads like green Magic Markers, Shun Mook M’pingo discs, and $1000/ft interconnects that had no discernable or measurable differences compared to standard cables.
After exhaustive testing of several amplifiers with several different speakers (some known to be “easy” loads and some known to be “difficult” to drive), Hirsch made some interesting observations that simultaneously explained why there were potential sound differences between amplifiers while at the same time remaining utterly faithful to the quantifiable, repeatable scientific process. It remains, in my view, the best explanation for this entire topic that I have yet seen.
Starting with the huge and all-important assumption that the amplifier under test is not being driven into distortion or being operated in a way that could elicit bad behavior, overheating, or engage any protection circuitry, Hirsch found the following:
Some pre-amp/power amplifier/speaker systems combined in such a way as to produce a very slightly rising or drooping frequency response across the entire 20-20 kHz audible spectrum. It could be a combination of the way the pre-amp and power amp combined on an input/output impedance basis, it could be because of the way a particular amp behaved with the specific load presented by that specific make/model of speaker, but there were system combinations where the frequency response showed a variation across the band.
/source/
Audioholics - The Loudspeaker & Amplifier Interface
Yes.
1) Tonality - The mere variations in Frequency Response is what makes them sound different. Use an EQ and that will be solved as well.
2) Synergy - The differences in output impedances change how amps perform with different speakers presenting different loads.
The perfect amplifier turns small electrical signal to big electrical signal with no changes to the FR at any load (impedance) variation of the speakers. A wire with a volume knob, as they say.
But who wants to buy that? Boring, dull, lifeless, fidelity.
1) Tonality - The mere variations in Frequency Response is what makes them sound different. Use an EQ and that will be solved as well.
2) Synergy - The differences in output impedances change how amps perform with different speakers presenting different loads.
The perfect amplifier turns small electrical signal to big electrical signal with no changes to the FR at any load (impedance) variation of the speakers. A wire with a volume knob, as they say.
But who wants to buy that? Boring, dull, lifeless, fidelity.
Vladimir said:
This is a good answer to another thread " tone controls" or even better 'an equalizer control'
lpv said:
As always it depends what you want eq for.
When I lived with a Quad setup I found the tilt control to be useful, mainly because the system as a whole sounded a little dark, a very slight uptilt worked very well. The other side of the coin being that I would not have owned such a system given the overfurnished nature of the room so probably I would not have needed the tilt control.
Other than that I am struggling to recall when I found regular tone controls to be of any use whatsoever. I would however, like an eq designed to help with the integration of a speaker into the room, a precise, variable eq working below about 500hz should do the job, but I have yet to find any such thing on a hi-fi amplifier.
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