I can't find your tech question now , i only saw Scott and Spladsky 's questions.
Unfortunately i was too tired to work on my player, make simulations and also understand what Scott really asked...although now, after so many hours of listening to music i'm a bit more relaxed and i could read again all the posts seeing that indeed Scott asked a very simple question.I'm sorry for that.
I WAS STUPID!
There's still a language barrier between us.
I hope now that i answered Scott the right way.
I did understand though from the beginning that applying this circuit to an mc cartridge might not be the best solution because of the noise ,but it allows to make an additional capacitive loading of the signal so that you can filter out ultrasonic resonances ...I didn't look for 2x 2sk117 in parallel for nothing.
My dac output was 1ma and the minimum guaranteed noise of 2sk117 is met at 0.5ma in the datasheet.I could have used 2sk369 or 2sk170 but their minimum noise is at 5ma while bf862 might be even worse so their higher transconductance might not guarantee anything at 0.5ma .
I already answered these questions but answering Spladsky.
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A thinner pcb would help also. I've used 0.8mm (1/32") boards with no problems.
Osh Park will give you 2oz copper for free on 0.8mm boards.
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Somebody have suggested the use of a long pcb to make the whole tonearm as in Nad 5120(Tesla) ...I think it would be a great idea actually with the right thickness and composition of the pcb so that the resonances would be attenuated .
This appears to be an example. The RIAA phono stage could be on the lower side.
JDDPTA-PCB TONE ARM FOR YOUR PORTABLE TURNTABLE. - Jesse Dean Designs
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Actually (oddly): no.
Using BJT technology, good commercial parts, we get a good OSI for a ~~2k-5k mag needle with Ie around 50uA. The output of that emitter follower is at 0.6k. We can run the input of the next stage at 250uA. Hiss voltage will be around 1/5th of the 1st stage. Noise Figure is not increased much. (Especially in Vinyl where the elephant in the room is the hiss in the groove.)
The only commercial circuit that i'm aware doing a similar thing at such low levels is the cassette tapehead preamp used in the Pioneer top models but they take benefit of even a bigger elephant in that room, the cassette tape hiss at 4.78cm/s.
I built that thing by adding the missing parts on another model which was stripped by the fet parts , left only with the op-amp using the holes and pcb traces that were identical just left unsued.
When deactivating the muting transistors(Pioneer, like many others has a smart sistem of hiding the preamp noise when not in contact with the tape ) i could clearly hear a loud noise due to that stage although i used even lower noise op-amps than the original one.
A.N.T. on Tapeheads is using a small 1 stage fet amp next to the head to deal with that noise in some high end cassette players that he is modding, but it's the dolby system that is more effective in reducing noise than any fet input.Fet are only oreffered for the high impedance and their low noise with high z sources...Otherwise Nakamichi had the only real solution with using a fet input in a preamp. You don't need a fet trz with an mc cartridge anyway.
At such low levels, 1/5th the noise is a lot of noise!
I built that thing by adding the missing parts on another model which was stripped by the fet parts , left only with the op-amp using the holes and pcb traces that were identical just left unsued.
When deactivating the muting transistors(Pioneer, like many others has a smart sistem of hiding the preamp noise when not in contact with the tape ) i could clearly hear a loud noise due to that stage although i used even lower noise op-amps than the original one.
A.N.T. on Tapeheads is using a small 1 stage fet amp next to the head to deal with that noise in some high end cassette players that he is modding, but it's the dolby system that is more effective in reducing noise than any fet input.Fet are only oreffered for the high impedance and their low noise with high z sources...Otherwise Nakamichi had the only real solution with using a fet input in a preamp. You don't need a fet trz with an mc cartridge anyway.
At such low levels, 1/5th the noise is a lot of noise!
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First of all that out of tune theory is very thin and pointless for this topic "purpose":
https://www.diyaudio.com/forums/eve...ized-music-causing-stress-13.html#post5773465
We are talking electrical domain and no matter what frequency is produced by the instruments , the audio electronics is still about harmonics, intemodulation harmonics and noise...not out of tune harmonics!
I wonder if the thickness of the elecTRICK current is discussed here
As for the BS i spout everywhere this will be the last argument you'll ever see from me everywhere from now on:
Well Scott being right and you enjoying listening to it can both be true. Knowing Scott I'm not going to bet against him
Just imagine what it will sound like when you get it right and you start - gasp! - listening to the music!
Jan
This was not spouting everywhere, it was in my own topic from the beginning. .
BOTH I and Scott were right because we were talking about different things, me being tired and Scott being doubtful at first about this circuit working at all and after that becoming suddenly very accurate about the fet resistance, but i answered his questions just by answering Spladsky who formulated it in a different way and not being involved with anger in a topic where
I challenged Scott at showing a picture of his real digital preamp for which i was only invited to buy an article in your publication.
I have the right to doubt you both too if you can't present the real thing, while silently accepting Billshurv affirmation that your device was presented at AES with no proof of it.
I think that i started that presentation in a reasonable way as i was building my circuit for a different application and in a different form at the same time:
https://www.diyaudio.com/forums/ana...t-phono-amp-inside-tonearm-9.html#post5770583
So...what is your goal Mr Didden?Is it linked with selling this:
Linear Audio | your tech audio resource
with no proof of the existence of a real thing doing what that article is presenting?
you'll never have another discussion with me!
I will never answer to your questions again on this forum.
And i don't care of what you think about me either.
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For historical reference
Yamaha's HA-2 (1979) and HA-3 (1982) commercial phono equalizers put a JFET front-end inside the tonearm headshell. The HA-2 used a bespoke universal headshell, while the HA-3 came with a potted JFET module that could be attached to the underside of any universal headshell or tonearm headshell.
YAMAHA HA-2の仕様 ヤマハ
YAMAHA HA-3の仕様 ヤマハ
Yamaha's HA-2 (1979) and HA-3 (1982) commercial phono equalizers put a JFET front-end inside the tonearm headshell. The HA-2 used a bespoke universal headshell, while the HA-3 came with a potted JFET module that could be attached to the underside of any universal headshell or tonearm headshell.
YAMAHA HA-2の仕様 ヤマハ
YAMAHA HA-3の仕様 ヤマハ
Not much different than what Bill and I were toying with, the CFP FET has lower distortion for high output MM. You could certainly current drive it and use a TIA like they did, it's just that USB soundcards with phantom power are readily available now (very little to build).
Well the first link mentioned MC and 0.1mV to 4.0mV, there might a loading resistor, just not shown (or not), Either way a JFET won't have good noise performance at these impedance levels.
well...the late 70's and early 80's were the best turntable and vinyl era.Nothing really notable was made in that area since then.
Now we see very expensive turntables, cartridges, tonearms and preamps based on new "manufacturing technologies" , but you can hardly find high quality new vinyls and few of them if any...equals their quality before the cd appearing.The recording studios are using very old lathes and the golden analog age sound engineers are long gone with their recording experience .I don't see any revival of vinyl recordings at the same quality as it was in the 80's just because the new generation can source anything from the digital world for less.
It's almost like me modding 90's cd players when nobody's listening to cd's anymore.
And anyway , the true sound source for those vinyls was the reel to reel 2 inch tape which now is used to make better digital recordings than the vinyl recording ever was.
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A single SK147 can do 0.5nV or so, a single BF862 @ 5mA is 0.63nV.
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Without knowing the flicker-noise knee frequency its hard to judge the audio noise performance from that datasheet.
A ZTX851 can do 0.27nV/sqrt(Hz) or so (not given on the datasheet though) with a knee about 150Hz. Ultra low noise amplifiers
Thats about the noise voltage of a 5 ohm resistor.
A ZTX851 can do 0.27nV/sqrt(Hz) or so (not given on the datasheet though) with a knee about 150Hz. Ultra low noise amplifiers
Thats about the noise voltage of a 5 ohm resistor.
Specs need to quote all conditions especially Id of each device. By actual measurement on a Quantec both the BF862 and 2SK170 obey almost perfectly the theoretical noise of a .66/gm resistor.
You can't easily do the "in the headshell " buffer with a bi-polar. The 1/f data has been published here several times as well in the press by Dimitri, typically both are below 100Hz. Only the more extreme MC's need <0.5V and this would just be to meet stylus off the LP or shorted input numbers, the issue actually playing an LP in simply moot.
What a relief, it's good to see the 797 actually meets its spec.
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0.5nV/sqrt(Hz) is the noise voltage of 15 ohms, so will be noticable on many MC sources. Yes surface noise may be louder, but Johnson noise hiss when the needle is up isn't great either, as it only has to compete with the background noise of the room. It can be very noticable when switching sources for instance, and during quiet sections. And given the wide range of MC impedances it makes sense to have as low a voltage noise as possible to be fair to them all?
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