I beleive class AB sounds better than A or D . The class A problem is simply money . Throw the same amount of money at a class AB amp and see what I am saying proved . Often class AB hides ripple . It is still there and makes the sound muddy . Sure common mode rejection does a good job . Ask it to do nothing and it will be happier . This might not have been true before spectrum analyzer ? We now can seek out the distortion and say if that stays I will not bother to listen . In the past it was guess work .
AB calculates as having the highest dynamic power . It has greater grip on it's power supply and can bootstrap the rails to swing up above the rail for a fraction of a second . Don't believe this at your peril if driving a coil . D has a less good grip on the power supply . As far as I can see D will make better use of the power supply . As an approximation it will need 50% less capacitance .
FM distorted is usually multi-path if a RF feed ( some will say FM when meaning internet of the same ) . This was seen as ghost images on old TV's . The only cure is a more directional aerial , in extreme cases a anti-phase aerial and mixer circuit . The beam angle of the anti-phase important . Often the anti-phase is smaller and could be the one that was replaced . If living near water that can be a problem . Worse when the tide is in . FM is worth getting right .
AB calculates as having the highest dynamic power . It has greater grip on it's power supply and can bootstrap the rails to swing up above the rail for a fraction of a second . Don't believe this at your peril if driving a coil . D has a less good grip on the power supply . As far as I can see D will make better use of the power supply . As an approximation it will need 50% less capacitance .
FM distorted is usually multi-path if a RF feed ( some will say FM when meaning internet of the same ) . This was seen as ghost images on old TV's . The only cure is a more directional aerial , in extreme cases a anti-phase aerial and mixer circuit . The beam angle of the anti-phase important . Often the anti-phase is smaller and could be the one that was replaced . If living near water that can be a problem . Worse when the tide is in . FM is worth getting right .
Last edited:
Rem acu tetigisti there I think. Crossover distortion in particular I have heard people say is not very audible, and yet I find it obnoxious, if not immediately obvious with everyday material. Then I thought about what musical material these people tend to use, mostly with fairly limited dynamic range, often products of recording studios with a lot of amplified instruments. For really wide dynamic range recordings in real halls, on occasions where one is listening deeply into the reverberant tails, down into the hall noise and microphone noise and other electronic noise, crossover distortion is more audible, and can resemble but not precisely mimic the low-bit digital without dither of the early days.
For me the sad thing is even when there is the potential of hearing really wide dynamic range, and doing a first-rate job reproducing it, modern urban and even many suburban environments are far too noisy to hear it. You have to be in the country, or in a very well-isolated room. And then you may realize that you have more tinnitus than you'd supposed
Agree , everyone i have ever heard sounds different , unfortunately they cost . Take a look at how much PSU 8K buys you , pathetic, yet sonic dash to spare ..
Try and find the PSU caps and yes it hates the big Bembeh ....
What's the problem, Wayne? I easily see 4 6,800uF caps per side, plus an additional pair lower down, in grey.
Please bear in mind that the energy capacity of a PSU is not only the function of power transformer size and electrolytic cap size, but also of operating voltage. By way of example, if I used the same at my +/- 51V, I'd have about 17.7 Joules. But at Krell's +/- 90V, that becomes about 55 Joules - and that's PER SIDE.
Enough to burn to a cinder just about every loudspeaker ever made.
About tinnitus, I think we all have it. Just like you see noise in a dark environment. Sensory horror vacui.
This noise might be useful to push signals that would otherwise go undetected over the threshold of perception, but I am just guessing here. Fact of the matter is that, like with high sensitivity microphones or optical sensors, my own sensor pod suffers from noise at high gain settings.
This noise might be useful to push signals that would otherwise go undetected over the threshold of perception, but I am just guessing here. Fact of the matter is that, like with high sensitivity microphones or optical sensors, my own sensor pod suffers from noise at high gain settings.
Curious comments. Either the parts of the world where others live are incredibly noisy, or you're listening at very low volumes ... I prefer realistic volumes, as a simple guide the reproduction of solo piano should sound the same as a 'real' piano, the SPLs should be similar. Of course, with energetic recordings this means that all background noise will be drowned out, as they would be for the live experience - impossible to hear the phone ringing, say ...
The downside of realistic sound levels is that all playback defects are then very obvious - requires a high degree of tuning of a system to allow this to be comfortably achievable ...
The Wikipedia entry for stochastic resonance is not that good, but relevant.
pull down R, CCS biasing op amp outputs to Class A for small mA loads has been suggested for decades
Brad, that's indeed the phenomenom I was pointing at, but I don't think it is part of accepted wisdom when it comes to our own senses yet. Just indications etcettera.
BTW, the effect is relevant when it comes to the discussion on the audibility of signals below the noise floor, which some think are inaudible. The opposite is more likely to be true: we often can perceive those signals, but in the absence of noise, they might be inaudible.
BTW, the effect is relevant when it comes to the discussion on the audibility of signals below the noise floor, which some think are inaudible. The opposite is more likely to be true: we often can perceive those signals, but in the absence of noise, they might be inaudible.
Rem acu tetigisti there I think. Crossover distortion in particular I have heard people say is not very audible, and yet I find it obnoxious, if not immediately obvious with everyday material. Then I thought about what musical material these people tend to use, mostly with fairly limited dynamic range, often products of recording studios with a lot of amplified instruments. For really wide dynamic range recordings in real halls, on occasions where one is listening deeply into the reverberant tails, down into the hall noise and microphone noise and other electronic noise, crossover distortion is more audible, and can resemble but not precisely mimic the low-bit digital without dither of the early days.
For me the sad thing is even when there is the potential of hearing really wide dynamic range, and doing a first-rate job reproducing it, modern urban and even many suburban environments are far too noisy to hear it. You have to be in the country, or in a very well-isolated room. And then you may realize that you have more tinnitus than you'd supposed
Yes,
Very obvious When listening to classical music , agree on steady state compressed music , most will not appreciate the difference, making it loud evens out ...
Ohh yeah , much less than the others i have had , you should see me holding on to the circuit breaker in the back just to hear the dynamic passages before tripping ..
Last edited:
AVP1,
In theory, I would agree with you on the subs, but I was quite surprised when I switched from a plate (Class AB) to an HCA1200 of about the same power on my subs that I DID hear a difference in definition. I have not had the opportunity to try a "good" class D on them. If you have a recommendation, I might consider it.
It has taken quite a few years to get analog amps to behave as well as they do. Class D has only been looked at for high fidelity use for a very short time. We are somewhat at the mercy of the chip makers. I guess we should think of this as just passing 741's for TLO74's. A useful technology for cars, portables, etc. Not quite there for high end.
In theory, I would agree with you on the subs, but I was quite surprised when I switched from a plate (Class AB) to an HCA1200 of about the same power on my subs that I DID hear a difference in definition. I have not had the opportunity to try a "good" class D on them. If you have a recommendation, I might consider it.
It has taken quite a few years to get analog amps to behave as well as they do. Class D has only been looked at for high fidelity use for a very short time. We are somewhat at the mercy of the chip makers. I guess we should think of this as just passing 741's for TLO74's. A useful technology for cars, portables, etc. Not quite there for high end.
Our ability to discriminate below the noise floor is best demonstrated by making a comment at a loud party with your wife on the other side of the room. I can guarantee she will prove our incredible ability to discriminate signals out of noise.
The class D that I've heard that seems o.k. is at least a hybrid of discretes and ICs. The NXP stuff is very conventional PWM and is reasonably mid-fi, and they do a fair job of fine-tuning the tradeoff between excess deadtime and shoot-through current spikes --- but I wouldn't consider it top-notch. I find it ironic, but probably explicable if one knew the internal politics, that Philips/NXP didn't pursue integrating Putzeys' approach. However one guy that remained there did a high-power version (high compared to the one reference design they published) and called it some sort of "ultimate", so the approach was certainly appreciated.
Gerald Stanley's invention and subsequent developments with interleaving I've studied, but not lived with. It's in a recent Mark Levinson amp, and reports have been mixed, with Stereophile not much caring for it, one owner writing in to say he thought it fine (and in all the areas where SP panned it). So I don't know.
As I've mentioned a few years ago I was part of a startup and inherited a design based on an IR reference design, and added a front end that I was pleased with and that permitted me to change the gain structure of the power amp section for higher loop gain and lower noise/distortion. The thing was close to being bulletproof and produced good sound to my ears driving a borrowed TAD speaker. But I didn't have near enough time to evaluate it before four of us abandoned ship in a clash with the other three. The IR design was a sort-of noise-shaped hysteretic free-running one, and although the specter of heterodyne artifacts attends to those, despite having two channels on the same small board I could only coax it into this with intentionally clumsy connections, which surprised me. The layout guy was very very good.
Not really, Frank. It's simply life.
I live on a corner of tripe crossorads, a classic crossroads with a third street passing just under the bridge. I have 3 tram lines and 6 bus lines passing by my house, and much of heavy druty truck traffic. Since 1975 until last year, my corner was measured as the noisest spot in the entire city of Belgrade (pop. 2 million). My only plus point is that I am on 8th floor.
With heavy duty Diesels powering the trucks and busses, I can't even dream of low noise before like 10 PM.
**************
MODS: This is NOT a plug, but a relevant parallel !!!
**************
I get EXACTLY that kind of comment regarding power lines. During office hours, when everything that uses electrical power is switched on, I have had people complain that the sound of their audio gear deteriorates quite audibly because of increased line noise. They say detail and ambience are lost, so they listen seriosly to audio only after 10 PM.
Most who bought it tell me that the filter does its thing and they are now free to listen to audio with no loss any time of the day.
I wish at least somebody here would not take my word for it, and I am surprised at the scepticism from professional quarters here, and take just a bit of time to see for themselves. Simply plug a 'scope into the mains and slide frequency from the anticipated 50/60 Hz upwards - you WILL be surprised.
Next, take a look-see at the amplitudes of these disturbances - do not be shocked if you see like 900 V here and there, obviously lasting a few microseconds only, but the sheer number of them.
While electrical noise is obviously different from audio noise, nevertheless it still wreaks havoc with your audio, or anyway much of it. Including Krell and Levinson.
So, between physical audio and electrical noise, you are caught between the anvil and the hammer. I am willing to bet many city dwellers don't listen before 10 PM or so. Countryside is different, and of course, even in cities, not everyone has the same magnitude of these problems.
Our ability to discriminate below the noise floor is best demonstrated by making a comment at a loud party with your wife on the other side of the room. I can guarantee she will prove our incredible ability to discriminate signals out of noise.
Not "our", but "their", female ability to hear anything to do with their vanity. They have integrated phase lock loop, 15 gang, quartz controlled tuners for anything pertaining to looks, age and weight. Especially theirs.
By comparison, Day Sequerra, Marantz and the rest are simply junk in comparison for sensitivity, selectivity, capture ratio, image, spurious and IF rejection and AM supression. Carrier and subcarrier suppression doesn't even come into it.
When interested in the topic, my wife will hear grass grow and paint dry. But she doesn't notice one speaker in her stereo system not working.
Last edited:
I am very lucky, as I have harnessed her golden ears for my speaker and amp evaluations. She has no respect for what it cost or my effort and will give cold accurate evaluations that are easy for even we males to understand: Yes or no. ( She worked with engineers most of her career so she can translate into our language)
barsco,
I too have been impressed by superb layout guys. The engineer would draw up his bright idea, I would make it work on the bench and our genius would make it work for real. It was a data recovery board that we had to tune to 50 ps, variable width traces and maintaining 50 Ohms around corners, equal time length traces. Magic.
Wonder if IR still has those app guides. I am sure the ideas have progressed from the AC power line/SCR switching we used to drive out reel moters. I laughed my head off when I saw the schematic for the Carver "Magnetic amplifier". de-ja-vu.
I too have been impressed by superb layout guys. The engineer would draw up his bright idea, I would make it work on the bench and our genius would make it work for real. It was a data recovery board that we had to tune to 50 ps, variable width traces and maintaining 50 Ohms around corners, equal time length traces. Magic.
Wonder if IR still has those app guides. I am sure the ideas have progressed from the AC power line/SCR switching we used to drive out reel moters. I laughed my head off when I saw the schematic for the Carver "Magnetic amplifier". de-ja-vu.
it feeled like eternity to have SIC devices widespread on market
and yet not all of them are popular in audio
- Status
- Not open for further replies.