The question you asked, namely, "How fast can a change in level take place from in to out?" For even a cheap opamp used as a lineamp, that will be on the order of less than a microsecond.
The whole "resolution" question. If you're talking about subtleties in the music, detail in the sound of the instruments, the preamp has zero to do with that unless the design is royally screwed up. Claims to the contrary are not backed up with actual data, just hype and gullibility. What a preamp does is switch sources and raise/lower the volume. "Resolution" is limited by microphones, loudspeakers, and room acoustics.
Good point!
I wondered about this and was just getting to that point, which is:
Is the smallest reproducible level even in a well designed speaker greater than that in amplifiers?
My guess is yes.
Even though I still want to know about all the pre amp stuff.
So do designers of pre amps as well, but if we take the whole system approach, then we'd have to consider the weakest link.
Still amp designers are still very interested in the small details as it relates to perceivable results, I hope.
Well, I'm still not giving up on my need to know things.
I have interests that relate to new directions in audio.
I want to see what the industry and designers of audio, that is, the people here, are all about.
This is by far the most interesting group of people I've ever met.
It is truly pleasurable and exciting and interesting to know that I may come here and speak with so many folks in the area of my interests.
Phil, what you want is very controversial, and not of the real world of measurement. For example, I could go almost to 100dB below hearing and still resolve a single continuous repeated signal, with enough signal averaging time on the test equipment. What does that tell you about what we hear? I can also show you measurements from standard test equipment that only shows a scramble of random noise and yet you might easily hear a tone through it.
Any CLASS A audio electronics, in theory, never really stops short of reproducing signal passed through it, but in practice, relays, wires and other connectors seem to often have limitations. That is why we pay so much attention to them and invest in better rather than cheaper parts. How the ear hears, is still a mystery to me, and I just know what we hear, not how we do it.
Any CLASS A audio electronics, in theory, never really stops short of reproducing signal passed through it, but in practice, relays, wires and other connectors seem to often have limitations. That is why we pay so much attention to them and invest in better rather than cheaper parts. How the ear hears, is still a mystery to me, and I just know what we hear, not how we do it.
"To maintain short signal paths with a minimum of wires special relays are used for audio signal switching. High tech telecommunications relays from Japan have been selected for the job. All contacts are gold clad silver and signal levels as low as 10 uA@ 10 mV are easily accommodated for superb low level music detail"
Apologies for digging this up.
The relay looks like a stock standard AGN type from Panasonic. 10mV 10uA quoted as the minimum switching load. However, note that these are limiting specifications and do not imply that signals below this will be negatively affected or cannot be switched.
Self only has nice things to say about small signal relays. I agree with him.
Apologies for digging this up.
The relay looks like a stock standard AGN type from Panasonic. 10mV 10uA quoted as the minimum switching load. However, note that these are limiting specifications and do not imply that signals below this will be negatively affected or cannot be switched.
Self only has nice things to say about small signal relays. I agree with him.
OK, if the pre amp and I assume power amp are potentially faster than
the rest of the chain, speed of ear, mic/mic pre, speaker/room, then the ability of the pre/power amp to not miss the fastest signals presented to them are a given.
Your thoughts about pre amps (not mic pres) as being the least problematic unless royally messed up is interesting because there are a lot of claims about the superiority of certain designs, as you pointed out, are just hype.
So, the only thing left for evaluation in basic pre amps, no tone controls, etc., are its build quality regarding long-term reliability and the sensibility of the electrical conditions of the inputs outputs relative to its employment for normal two-channel home use.
Is this correct?
If so, and no one has any additional comments to the contrary, then I assume that my concerns as to what makes for a superior sound system lay elsewhere.
One other thing please.
John Curl responded to this post with the following:
... but in practice, relays, wires and other connectors seem to often have limitations. That is why we pay so much attention to them and invest in better rather than cheaper parts."
John is addressing pre amps, I guess, although his remarks do apply to other electronics.
So, if what you say is true, we need only be concerned with relays, wires and other connectors regarding pre amps as the only concern, since you say that what a preamp does is switch sources and raise/lower the volume.
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Phil, I think you say (without saying) a very profound element: the first and most important step in the design is quantitative and objective performance attributes, e.g., gain, bandwidth, input impedance, output impedance, balanced or single-ended, voltage range, noise- these are attributes that a user needs to determine in advance. If these are well-specified by the user, then, yes, it's down to reliability, look and feel, and perceived value of exotic design or an interesting story. If two competent line stages have their identities concealed, no one has ever been able to distinguish one from another. If I were to buy a preamp, I might want a Bryston or Parasound or Vacuum State because of the build, a luxurious feel, a good warranty, or how the "philosophy" appeals to me personally, but there won't be any difference in the sound waves that hit your eardrum.
Phono stages are a whole different story.
Relays and connectors, for sure, especially because of reliability. Many decades ago when I was a TV/hifi repairman, probably half the problems that came in were due to connectors/solder joints/switch contacts. It's still a weak point in much gear, but at least I got my first intuitive understanding of Pareto analysis.
Wires, again there's a lot of hype and Superior Dances, but no-one has ever demonstrated that anyone can tell one from another (assuming nothing pathological) when they have to use their ears alone. If it makes you feel better to use prasodymium-coated palladium, have at it, but that's not changing the sound waves, either.
Phono stages are a whole different story.
Relays and connectors, for sure, especially because of reliability. Many decades ago when I was a TV/hifi repairman, probably half the problems that came in were due to connectors/solder joints/switch contacts. It's still a weak point in much gear, but at least I got my first intuitive understanding of Pareto analysis.
Wires, again there's a lot of hype and Superior Dances, but no-one has ever demonstrated that anyone can tell one from another (assuming nothing pathological) when they have to use their ears alone. If it makes you feel better to use prasodymium-coated palladium, have at it, but that's not changing the sound waves, either.
Hi Bonsai:
Thanks for your efforts, especially visiting IRD site.
If you've been following this thread, you'll understand that I am not a designer.
However, I'm very seriously involved in music, music production, synthesizer patch design, audio effects design, electric violin and much more.
So, for sure, I do want to understand as much as possible, especially when considering a new amplification chain for my monitors.
Even if money were no object, I see that making a choice regarding excellence in quality and or accuracy of sound posses many considerations, for me at least.
Yet, as shown in this thread regarding pre amps:
Apart from the quality of the connectors, relays wiring, switches, etc.
SY, one of our fellow members, points out that quality of sound is not an issue or that provided the pre is not royally screwed-up, there won't be any discernible sonic differences.
Yet even on the forum at large, we see that this is debatable.
I had stated that, if there are no other contributing comments to the contrary, then I can assume that either no one actually wished to, had not yet gotten around to it or that SY's view is correct.
Please be sure that I appreciate SY's time end effort and that he presents a logical view, but I would like to know your thought as well.
Regarding the IRD. I should expect this pre amp to provide clean, low-noise, accurate signal transfer, and unless someone points out otherwise, reliable switching and the other things that ONLY make a difference regarding long life, etc.
I received a number of comments that basically attempted to make the designer seem dis-ingenuous or hyped or what else.
What is your impression of the unit please.
I must shortly purchase a ready made warranted product.
Would you know of other units, off-the-shelf, in that price range, that are well designed?
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Just make sure that, if it is a preamp, that it IS class A everywhere. If it is a power amp, try to get high output bias current of at least 0.5A Even more is better. True class A is not as important in power amps, but the crossover region of the outputs can lose you information and give you listening fatigue from the generation of high order odd harmonics and corresponding IM. There is more, like lower noise, dynamic stability, etc. , but class A is really important, in the area where we normally listen. ANY class A circuit will get lower and lower in distortion as you reduce level, what we call monotonically. Unlike a telescope that gives up on resolution depending on its effective width, any class A circuit will always get more accurate. This is the key.
Hi John:
I was aware that a true complete Class A design does not suffer from switching distortion.
I understand "Switching" to mean that in class AB, the output devices are usually on (not switching) at a low level to prevent heat, then at some higher level, they become class B (switching) and that the cross between those two states is potential or definitely for distortions with various designs yielding better results.
I was not aware of class A pre amps, but now that I think about it, I have seen integrated designs that are classed as true/complete class A, so I gather that those integrateds are class A in pre and power stages
But, transistors are switches.
Apparently, switching in transistors does not pose the same type anomaly,(between classes) when correctly chosen and implemented.
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Hi Bonsai:
A short reply from IRD:
... I used the best relays made, this is the source input contact specs, they have excellent specs for audio reproduction."
Bonsai:
Does the above add anything further regarding your observations of the IRD's relays' performance?
From what I've seen, usually class A are more expensive.
The pre amp and mono-block power amps from IRD Audio are fully DC coupled from in to out, but I believe not class A or not full "A".
Unless someone can point me to an off-the-shelf product that meets John's recommendations for about 1,000 dollars-pre and power, these look promising both sonically and build quality.
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Hi SY:
I'll accept your view of that unit and others that are in that category, at least for now.
About Mr. Curl:
I don't know him personally, nor am I as qualified to comment on his abilities as others may, but I want to be clear that when I say that I accept your analysis of his or other pre amps in general, I mean no disrespect to John.
This is true because I can only ask and wait for replies from those who are qualified to do so.
John did recommend that the one important consideration for a pre is that it should be 100% class A.
Your thoughts on that please?
So far, your statements have not been challenged.
At this point, I can only evaluate a pre amp based on the points you have raised so far.
Thanks for your time, which I do appreciate.
As far as i can tell the IRD Purist works with Opamps. It´s well made though and is very afordable. I can show you a way how you can bias that OPamps into class a if you like.
I have a photo of the Blowtorch on my other computer. It is owned by a friend of mine who had more or less all interesting components over the years. He seems to be happy with the Blowtorch and i can ask him why he uses it.
I have a photo of the Blowtorch on my other computer. It is owned by a friend of mine who had more or less all interesting components over the years. He seems to be happy with the Blowtorch and i can ask him why he uses it.
Dear,
Interesting subject.
And John (Curl) is right. We hear so many things that is hard to explain with measurements.
But I think we should categorize the subject into 3 catogories.
-Resolution
-Dynamic range
-Noise floor
Resolution:
Correct me if I am wrong, but I see resolution like this, Imagine a pool full with green and a few red tennis balls. Till which degree are we able to pick out a few red tennis balls in the mass of many green tennis balls, before it just all look total green to us. Many good producers, add so many many layers of synth tracks, or string arrangement far on the back-ground of a music track. Only with a few systems suddenly one is able to pick them out. If this happened you get the message of the producer/composer much clearer. This can be independed of noise-floor because, resolution can matter with signals all above the noise-floor.
How would one measure this? It is a hard question. But I am convinced we must searched it in harmonics and harmonic behavior.
Dynamic range:
Is the ability to distinguish difference between velocity of tones between it's lowers and loudest amplitude. Maybe the noise-floor can play a part here in the lowest to reproduce velocity in tone.
Noise-floor:
I think noise will always degrade all above subjects. A higher noise floor will degrade dynamic range in the lowest to hear tone or harmonic. It will degrade the resolution on levels close to the self noise of the system.
I think systems with very low noise-floor levels can excel in resolution, dynamic range detail, but of course there is much more in a design that contribute to this.
@ Joachim Gerhard, Can you show what you mean with your opamp class A biasing? Is this the well known trick with a current source or resistor at the output of an opamp?
With kind regards,
Bas
Interesting subject.
And John (Curl) is right. We hear so many things that is hard to explain with measurements.
But I think we should categorize the subject into 3 catogories.
-Resolution
-Dynamic range
-Noise floor
Resolution:
Correct me if I am wrong, but I see resolution like this, Imagine a pool full with green and a few red tennis balls. Till which degree are we able to pick out a few red tennis balls in the mass of many green tennis balls, before it just all look total green to us. Many good producers, add so many many layers of synth tracks, or string arrangement far on the back-ground of a music track. Only with a few systems suddenly one is able to pick them out. If this happened you get the message of the producer/composer much clearer. This can be independed of noise-floor because, resolution can matter with signals all above the noise-floor.
How would one measure this? It is a hard question. But I am convinced we must searched it in harmonics and harmonic behavior.
Dynamic range:
Is the ability to distinguish difference between velocity of tones between it's lowers and loudest amplitude. Maybe the noise-floor can play a part here in the lowest to reproduce velocity in tone.
Noise-floor:
I think noise will always degrade all above subjects. A higher noise floor will degrade dynamic range in the lowest to hear tone or harmonic. It will degrade the resolution on levels close to the self noise of the system.
I think systems with very low noise-floor levels can excel in resolution, dynamic range detail, but of course there is much more in a design that contribute to this.
@ Joachim Gerhard, Can you show what you mean with your opamp class A biasing? Is this the well known trick with a current source or resistor at the output of an opamp?
With kind regards,
Bas
Nor do I (mean disrespect, that is). I know John, I know his designs, and despite fulfilling the market needs for fetish objects, his designs are (for the high end) atypically solid, reliable, and have superb measured performance. If I were a person who bought amps, I would not hesitate to buy a product he designed.
Thank you.
I will have the IRD pre and mono-blocks shortly and that will be interesting about biasing, but at least for the trial/evaluation period as warranted, I will wait and see.
Yes, thank you regarding your friends possible comments regarding the Blowtourch. It will be interesting.
I hope that I am allowed to state what the Blowtorch preamp really is:
It is what we came up with, my business partner Bob Crump and I, to make the very best preamp that we could, for both ourselves, and for a limited number of customers.
The 'performance art' part of the preamp came from having to make something that our customers would accept in their system. However, very little about the preamp is arbitrary. The thick aluminum, almost airtight case, is on purpose. It is a good heatsink that allows us not to punch vent holes to let the heat out. It is a very good interference filter, that keeps RFI from computers, lamps, etc, out.
The Blowtorch has big knobs in front, showy, but necessary. The only other way to turn those big military switches is to put a vice grip plier on them, and that is unseemly.
We chose the switches, inside, because they sound better than any relay we know, and I had 30 years of experience with small signal relays, including several preamp designs, before going over to Shallco Silver switches. The circuitry, while simple in through-path, is exotic. All direct coupled with 4 quadrant symmetry to handle both single ended inputs or outputs without any negative feedback.
We used this preamp in listening contests with other preamps. We almost always won, however some tube gear was just as good. This was our goal, to win listening contests. Before making this CTC Blowtorch design, I was using passive as a line stage, and manually changed cables when I wanted to listen to another musical source. This I found better than ANY previous preamp that I owned or designed. They went to the closet, where they remain today.
It is just like trying to find the best wine tasting experience possible. Or the best restaurant experience. Some people throw their expendable income in that direction. Do I criticize? No.
It is what we came up with, my business partner Bob Crump and I, to make the very best preamp that we could, for both ourselves, and for a limited number of customers.
The 'performance art' part of the preamp came from having to make something that our customers would accept in their system. However, very little about the preamp is arbitrary. The thick aluminum, almost airtight case, is on purpose. It is a good heatsink that allows us not to punch vent holes to let the heat out. It is a very good interference filter, that keeps RFI from computers, lamps, etc, out.
The Blowtorch has big knobs in front, showy, but necessary. The only other way to turn those big military switches is to put a vice grip plier on them, and that is unseemly.
We chose the switches, inside, because they sound better than any relay we know, and I had 30 years of experience with small signal relays, including several preamp designs, before going over to Shallco Silver switches. The circuitry, while simple in through-path, is exotic. All direct coupled with 4 quadrant symmetry to handle both single ended inputs or outputs without any negative feedback.
We used this preamp in listening contests with other preamps. We almost always won, however some tube gear was just as good. This was our goal, to win listening contests. Before making this CTC Blowtorch design, I was using passive as a line stage, and manually changed cables when I wanted to listen to another musical source. This I found better than ANY previous preamp that I owned or designed. They went to the closet, where they remain today.
It is just like trying to find the best wine tasting experience possible. Or the best restaurant experience. Some people throw their expendable income in that direction. Do I criticize? No.
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