Me too. I have spent a ridiculous amount of time, effort, and money in the last year or so repairing/restoring/modifying/restoring an old vinyl playback system, and built two phono preamps (one opamp based for MM and one discrete for MC). I have no delusions about this stuff, but I enjoy the process (of building, and of playing records) and I like trying to get the most out of those old discs. They can sound quite nice if you ignore the noise and clicks and warps.
David, I usually agree with a lot of what you say, but playing records is fun! Takes me back to my youth
. And from the technical end, phono preamps present some unique challenges.Now we just need to get Ed to ask a coherent question or, better, make a coherent statement.
See the chart from the old study from SHURE
This is vinyl modulation velocities.
At 1kHz there is material 20dB above 5cm/sec
At 5kHz to 10kHz there is material 24db above 5cm/sec
At 10kHz to 20kHz there is material 20db above 5cm/sec
For the case of a non mistracking cartridge, I would consider then a 30db figure above 5cm/sec as barely adequate.
Example1
MM cartridge, 5mVrms at 5cm/sec
For +20dB, unequalised output is 50mVrms (70mVp)
For +24dB, unequalised output is 80mVrms (112mVp)
Aiming for +30dB, unequalised output is 158mVrms (221mVp)
Example2
MC cartridge, 0.5mVrms at 5cm/sec
For +20dB, unequalised output is 5mVrms (7mVp)
For +24dB, unequalised output is 8mVrms (11.2mVp)
Aiming for +30dB, unequalised output is 15.8mVrms (22.1mVp)
A mistracking cartridge will produce higher level signal than these.
A cartridge non matched to the arm, and non damped will produce subsonic signals well close to the equivalent of 5cm/sec. These will not overload the input but may cause overload after the RIAA equalisation.
George
>Edit.Slightly wrong cartridge azimuth and the dreaded antiskating dynamic miss adjustment, eat 6dB from the headroom for lunch.
Then it is the scratches and dirt.
I would go for +42dB above 5cm/sec.
This is 630mVrms (880mVp) for the MM of the example1 and 63mVrms (88mVp) for the MC of the example2
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Really ,
Didn't you state you dont care about sound and now your input is what ???
* you dont like Cary
* You dont like Mac's
* you hate toobs
that's some serious Irony there budlow .....
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No, a.wayne, what I said was I wouldn't go back to tubes. I've used Cary and other tube equipment and I don't want to do it with tubes. I am perfectly happy with solid state devices, though I have been rather disappointed in some of the monolithic amplifiers I have heard. I will keep my Mac tuner just because it hardly ever needs new tubes and pulls in stations better than so many other tuners I have tried. At the same time I have an old SAE tuner that is also really good, all solid state. I'm not saying I don't like great sound, just not going to do it with toobs!
I'm not pro toobs, havent has one in 20 yrs ...
No one wants to go "back" but how far forward have we gone , yes technological advancements are evident , but i challenge you to listen to a reference Sota system from the 80/90's and one today and rate the advancement. Tubes have advantages , there's solid technical argument for Hybrids and unless you plan on doing mission critical expeditions with the great one , nothing wrong with the mix...
Just saying ...
No one wants to go "back" but how far forward have we gone , yes technological advancements are evident , but i challenge you to listen to a reference Sota system from the 80/90's and one today and rate the advancement. Tubes have advantages , there's solid technical argument for Hybrids and unless you plan on doing mission critical expeditions with the great one , nothing wrong with the mix...
Just saying ...
Smart people = Welcome
Smart ar$$es = Unwelcome
I don't understand the continued animosity shown towards JC ? OK, i wouldn't shell out for a Baybe thingy http://www.diyaudio.com/forums/everything-else/257047-bybee-another-look-etc.html but even because of that, we could still learn from his posts. I know i have
Smart ar$$es = Unwelcome
I don't understand the continued animosity shown towards JC ? OK, i wouldn't shell out for a Baybe thingy
http://www.diyaudio.com/forums/everything-else/257047-bybee-another-look-etc.html but even because of that, we could still learn from his posts. I know i have 
You know, I find that a bit offensive, on a couple of scores. First, I didn't really see any "derogatory" answers. You asked a silly question, and you got far more reasonable answers than it deserved. Heck, I gave you 4, and they were all honest and informed answers to your question.
Second: I don't think you know what "Socratic method" means. Sure, Socrates asked his students seemingly simple questions to lead them to the truth. The difference is, he asked questions to which there was only one answer he couldn't refute (or didn't want to refute), and he listened to the answers.
You have asked a series of open-ended questions which don't lead anywhere, and which become more and more difficult to even parse, an M.O. we have seen from you many times before. You don't listen to the replies to your questions, or respond to them. Then when nobody can understand what you are asking you get shirty because nobody wants to play.
If I may make a couple of constructive suggestions: 1. Go back and read your Plato, see how Socrates did it. 2. If you have something interesting to say, about JC's experiments or anything else, then say it and stop pussyfooting around. While you're at it, stop characterizing others' replies as "derogatory" just because they aren't what you want to hear.
Finally: what's with the "warning"? Do you really think everyone here is on the edge of their seats, waiting for you to impart secret knowledge? I come here to hear intelligent discussion from people smarter and more knowledgeable than me (I count you in that class, but it's not very exclusive), but not to have some putative secret dangled in front of me and to be told that to get it I have to behave.
I'm not pro toobs, havent has one in 20 yrs ...
No one wants to go "back" but how far forward have we gone , yes technological advancements are evident , but i challenge you to listen to a reference Sota system from the 80/90's and one today and rate the advancement. Tubes have advantages , there's solid technical argument for Hybrids and unless you plan on doing mission critical expeditions with the great one , nothing wrong with the mix...
Just saying ...
I don't know about the definition of 'sota systems' but any well designed 21st century speaker runs rings around its brethern of the 80-ies.
For electronics, it may be different; sound quality wise I agree there was not much progress, mainly because 30 years ago well-designed audio electronics did all there was to do.
Jan
Hmmm ... all these "30 years ago well-designed audio electronics" must have been hidden away in a secret cupboard, under lock and key, only accessible to those in the know - because I never came across them ...
I actually was astonished when I finally heard the first power amplifier working properly, after about 6 years of looking - I thought they didn't exist ...
I actually was astonished when I finally heard the first power amplifier working properly, after about 6 years of looking - I thought they didn't exist ...
Very good! Now if one was to design a preamp for an MC cartridge one issue is added noise. In RF work we would talk about noise figure. A good figure would be 1 dB, unfortunately designing here for the lowest source impedance here would mean the preamp would need to have added noise of less then 100 pV/sqrt(Hz).
Paralleling 4 of the LME4990 will get us to about 400 nag/sqrt(Hz). That is equal to a 10 ohm source resistance.
Now if we use a standard two resistor feedback network there will be one resistor to ground at the inverting input. If we make that resistor 10 ohms then it will make as much noise as the amplifier. If we make it 1 ohm that will reduce it's noise contribution by a factor of sqrt(10).
With a 1 ohm resistor and an op amp that is rated to drive a 600 ohm load the minimum voltage gain would be 600. So with 18 volt supplies our maximum input voltage would be 30 mV.
BTY why do you think the derogatory question comment was aimed at you? Part of the Socratic method is that it shows the level of knowledge of the body. The teachers also learns. Now would you like to review all the comments?
We agreed on that a long time ago, John.
The problem with op amps is that they are pretty well closed, they are what they are and there isn't much we can change in their basic sound. Sure, we can force them more into class A, we can add current boost, but that's about it.
With discrete, the designer keeps full control of the whole circuit from beginning to end, and is free to make his own choices of using whatever device he likes at each design stage. Thus, he keeps full control of the sound.
This should not be taken as me being anti-op amp. Some of them can be made to play good music, some even very good music. Ultimately, I do have a reasonable collection of them on stock right here at home.
They are cost effective, there's no denying that fact. And not every friend I have wants to have the ultimate at home, many are quite happy with reasonably good, either because their systems can't use better effectively, because of cost considerations, etc.
In short, op amps are very useful devices which definitely have their place in the audio world, they have improved much in comparison with say 30 years ago and are still evolving, which I take as good news.
But for the very best, discrete is still the way to go.
It's more complicated than that. With an MM, you can't ignore the inductance, and the load R in parallel with the load C also comes into play.
See RIAA Noise Calculator for an aid to calculating this stuff.
Thats why i said system, the comment was not fleeting , we do the comparisons regularly enuff to be able to say such, thats why toobs, tapes and LP's are still hanging around , individually flawed , yet packaged correctly is as musical satisfying as any today .
As to speakers you must be talking Box speakers , yes they have benefitted tremendously from software ( as others to a lesser extent) but are you sure much better , Quite a few raving over those old WW horns carted around to shows lately ..
Heard an old Infinity IRS. system a couple years ago , cant say the wonder boys today have surpassed them , i wont even get into the quad 57/63 setups that were very satisfying ..
advancement by MM...
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Thats why i said system, the comment was not fleeting , we do the comparisons regularly enuff to be able to say such, thats why toobs, tapes and LP's are still hanging around , individually flawed , yet packaged correctly is as musical satisfying as any today .
As to speakers you must be talking Box speakers , yes they have benefitted tremendously from software ( as others to a lesser extent) but are you sure much better , Quite a few raving over those old WW horns carted around to shows lately ..
Heard an old Infinity IRS. system a couple years ago , cant say the wonder boys today have surpassed them , i wont even get into the quad 57/63 setups that were very satisfying ..
advancement by MM...
'Musically satisfying' is not the same as 'high fidelity' in the literal sense though.
As to speakers, there has been a lot of progress in materials for cones, magnet stuff, general the mechanical properties of drivers have improved, much more so than the electronics.
That doesn't mean that all comtemporary speakers are better, but the potential certainly is there.
jan
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