I will quote myself this time because i don't like my words being reinterpreted OUT OF CONTEXT.
Please read it for 10 times if you can't undestand that .
When you're ready look up the regulators for the phono section of Kenwood l-02A and see if its specs can be obtained due to its regulators performance alone or only if you consider the phono section and its regulators as a WHOLE.
I said that for about 10 times by now that i cannot consider any other solid state phono preamp better than that only by judging its specs. The most important spec in a phono chain is the max input signal and the only ones i know that rivals l-02a are the tube preamps and maybe a bit closer , the separate preamp of Nakamichi CA-7.
Kenwood did separate preamps too very much looking like Nakamichi ca7 in design or concept, but kenwood still claims the absolute performance with Kenwood l-08c yet i consider the slightly lower performance phono preamp found in a receiver better than a separate phono preamp and a power amp because it follows a very good principle of wholistic design.
I'm also curious if you can explain Kenwood l-08c performance by its 4 transistor parallel regulator!
I prototyped ot tweaked about 10 different phono preamps in all technologies and replicated some of the most well known ones and from that i learned that you cannot review a solid state phono preamp separate from the rest of the chain disconsidering perfect match with the power amp and claim having the best experience. Kenwood agreed with me , that's why they sold l-02a receiver and the kenwood l-08c preamp paired with kenwood l-08m power amplifier only in Japan. Nakamichi probably did the same with ca7 and pa7 initially...but never considered moving its entire production in a luxury brand like Accuphase.We are simply too attached to our ways...
Besides you can find the real world measurements done about 10 years ago of that l-02a receiver on Hi-fi do Japan or a similar japanese site and see that the measurements of a 30 years old amp at the time were better than the ones found in the service manual.I hope you don't think that Kenwood got by accident to be the main contractor for servicing the radiocommunication equipment of US army since 1980 or that its owner bought Accuphase in a charity shop ...
http://www.thevintageknob.org/kenwood-L-02A.htmlhttps://elektrotanya.com/kenwood_l-02a.pdf/download.html
https://elektrotanya.com/nakamichi_ca-7-a-e_ca-70_sm.pdf/download.html#dl
https://elektrotanya.com/kenwood_l-08c_sch.pdf/download.html#dl
Find me something better please! I want to learn more about the modern phono preamp technology!
Because most of us are too lazy to clean each damn vinyl every single time we listen to it and i don't see many people listening vinyls in a filtered hyperbaric pharmaceutical or medical facility .Other than that i don't particularly like scratching or any other sudden stylus movement driving my preamps into hard clipping.Tube phono preamps don't usually have a problem with that as there's a built in compressor in every tube, but silicon circuits need a lot of care to avoid pops and cracks .There's even a bigger problem with choosing the amplifier following a phono preamp with no built in antisaturation circuits as its volume pot won't prevent a sudden 40 db signal raise to blow out your speakers.The whole recording industry relies on compressors to tame lower speed velocity transducers like microphones why wouldn't the usual audiophile consider a simillar approach for its much faster stylus moving a magnet or coin in a cartridge?
I'm sure the Kenwood L-02A was a standout state of the art masterpiece in its day. I can't find any measurements, but based on Kenwood's own specifications today's state of the art phono preamplifiers outperform the L-02A's phono noise performance a factor of more than 10 times. The regulators in the L-02A use noisy zener diodes as the reference; it's most likely they were contributing to the noise floor of the preamp stage. I don't know what there is to argue about.
For what it's worth I have no aversion to classic designs. My amplifier is an Accuphase E-303X which has a noise spec on MC equal to L-02A.
For what it's worth I have no aversion to classic designs. My amplifier is an Accuphase E-303X which has a noise spec on MC equal to L-02A.
Measurement ... schmeasurement! 
I recently had an interesting comparison of my own (jfet-based) 'Muse' MC phono stage against an AR Reference 3SE tube phono stage.
Where the 3SE won out was in the georgeous "tonal body" it delivered. I'm wondering what would you measure to show this difference, @dreamth ?
Andy
I recently had an interesting comparison of my own (jfet-based) 'Muse' MC phono stage against an AR Reference 3SE tube phono stage.
Where the 3SE won out was in the georgeous "tonal body" it delivered. I'm wondering what would you measure to show this difference, @dreamth ?
Andy
The measurements could be found in the spec section of vintageknobs page too.
Those SNR numbers are phono in to speaker out for a combo that outputs170watts /8ohm per channel...not for just a phono preamp.
SNR can easily be improved to Insane numbers, but for vinyl you won't get anything more past -70 db which can be provided by the cheapest two transistor phono preamp you find in any 70's cheap receiver.
That is why i mentioned input max signal to be the real improvement not the SNR.
I' m not gonna play into the stupid arguments of 70 years old guys pretending to hear anything under the vinyl or tape noise treshold because I KNOW that is impossible.Dolby an DBX proved that we don't hear audible noises at all if the sound level passes some bariers where our brain processing behaves like a true compressor . If you doubt that call Ray Dolby spirit and talk to him.
At the time Kenwood used the lowest noise j fet available the 2sk146v which was made out of matched 2sk170 V ...pretty rare transistors too equivalent i think to two paralleled 2sk 170 BL but lower capacitance .
Getting lower noise by paralleling multiple jfets was done by Nakamichi for the mc stage and Denon and Sony for both mm and mc section, but there are a few catches that prove denon and sony were wrong:
First , 2sk170 has a large internal capacitance compared to more modern low noise j fets so you couldn't use too many on mm input without dinamically loading the cartrige.Nothing can stop you replacing the original 2sk146 with lsk486 i suppose...
Second, in mm stages they were the input trz of a bipolar cascode and the huge transconductance you get by paralleling input j-fets makes the cascode bipolar transistor to violently slew its current into a fairly low collector resistor and that needs to be tamed or clipping will not be limitted in time by the feedback network with all its time constants .It's quite useful to see that l-02a used the lowest impedance feedback network ever used in actuve riaa phono preamps and that is not only for lowering overall noise.APT Holman didn't used cascodes, but loaded the input jfet with a bipolar transistor ccs so their bipolar transistor feedback got both lower input noise due to a lower impedance nod for the feedback path and higher speed feedback as bipolar internal impedance(both reactance and resistance) are lower in bipolar trz and the transconductance is usually 40 times higher than j-fets for similar currents.
As far as i know Kenwood is the only company that implemented the same techniques used in high class op amps of limiting the base current of the cascode transistors.If you check several similar schematics including the best known sony or denon phono preamps with a similar structure you'll see kenwood allowing for about 8 times lower base current than the competition .You also see that every gain stage has antiparallel antisaturation diodes and to my knowledge only Nakamichi and AIWA did that in some rare models .I didn't see all the schematics of every audio equipment ever made obviously , but i chequed all that were talked about on about a hundred sites and had an available schematic.
The techniques used by Kenwood were mandatory to tame the composed cascode of a large current j-fet and a bipolar trz and nobody else used them all in one phono preamp with j-fet inputs. Starting from there i looked more into bipolar tranzistor input phono stages as i figured out at some point that bipolar tranzistors can give you a good enough experience with less effort.No wonder for me that some of the best phono stages are entirely made with bipolar technology.
Most probably the harmonic distortion spectrum...My best sounding phono preamps were undoubtedly tube preamps and i stick with them .They also measured the best under stress.Measurement ... schmeasurement!
I recently had an interesting comparison of my own (jfet-based) 'Muse' MC phono stage against an AR Reference 3SE tube phono stage.
Where the 3SE won out was in the georgeous "tonal body" it delivered. I'm wondering what would you measure to show this difference, @dreamth ?
Andy
I'm not saying you can't measure the difference in sound, mate ... simply asking WTF do you measure, to confirm the difference in sound?
Andy
Fair enough. Some people would say "tonal body" comes from the harmonic profile. I just try and avoid vague audio terms like that.
Have you ever actually listened to a tube phono stage?
Andy
As opposed to hearing it? As in actively? Of course. How else do you listen to records? I've designed and built several tube phono amps. All of which perform adequately, my go to being my actively loaded amp using 8 dual triodes.
For me, an amplifier should be as close to a wire with gain as practical. Anything else is a virtual effects box IMHO.
For me, an amplifier should be as close to a wire with gain as practical. Anything else is a virtual effects box IMHO.
Agreed. Any component that adds, or subtracts, something from the original recording isn't high fidelity, but high frivolity. And there is a simple test: does doing it twice or adding twice the amount (e.g. in the case of cable) change the sound even more?
Both switch-mode and linear supplies would work for a phono preamp, if noise is kept low. Question is, why the complexity of a switch-mode supply for such a low current application, where efficiency is a non-issue, and the switching noise could well be one? Use two simple IC linear regulators and get it over with.
Hello. Back to the starting topic. I have found another example of a switched source phono preamplifier.
And this one has dual switching power supply. One on the 5 volt wall wart and one on the internal preamplifier board, with a step up to deliver 12v+ and 12v-.
I would like you to see the measurements. and of course I'll buy it and then I'll tell you.
https://www.soundstagenetwork.com/i...reamplifier-measurements&catid=414&Itemid=547https://ifi-audio.com/products/zen-phono/
And this one has dual switching power supply. One on the 5 volt wall wart and one on the internal preamplifier board, with a step up to deliver 12v+ and 12v-.
I would like you to see the measurements. and of course I'll buy it and then I'll tell you.
https://www.soundstagenetwork.com/i...reamplifier-measurements&catid=414&Itemid=547https://ifi-audio.com/products/zen-phono/
Again not disagreeing with this, just my own experiences don't seem to confirm this fairly widely communicated wisdom.
I've used everything from tube phono stages with enormous overload specs (like 120mv IIRC) and passive RIAA between two gain stages, as well as the cheap TC-750 with a cheap switching wall wart and I believe RIAA via feedback. Everything I've read indicates these two should sound remarkably different in terms of surface noise, and yet, they don't, they sound remarkably similar as far as pops/ticks go.
Maybe the TC-750 recovers quickly enough from clipping, I don't know. All I know is, at least in terms of surface noise, I don't hear much of a difference between the two.
One "secret" of tc 750 is that it' s using bipolar transistors with high resistor value for bias to limit the current gain when the input gets too high.That bias resistor is also raising the current noise which lowers the transients dynamics, but we can't clearly hear the difference and that makes bipolar transistor phono preamps sound apparently better on dusty records.
A second "secret" is that the riaa filter is placed in a current feedback network being very fast.And this preamp also have a voltage feedback too...so i'd say it looks like a wisely elaborated one.
This "fairly wisely comunicated wisdom" is actually not that wide...i think that for a few years I'm the only preacher of this dusty theory here on diy audio although i picked it up a long time ago from another site of a very well known member of this forum .I didn't preached it because I believe it, but because I had it verified in the real wold on many preamplifiers until I actually internalized it as my own.
It might not be everyone experience...I can get it as thrre are countless phono preamps on Earth within very different setups ..it was my experience for sure though as i only listen to these preamps on headphones with pretty highsensitivity, undamped by cubic meters of air..
Truth is that my first phono preamp I ever listened was a tube one made by myself and tubes are very forgiving with high input transients too.High gm Jfet transistors aren't unless they are used with very low voltage gain or inside a circuit that behaves like a compressor or AGC.
https://www.superbestaudiofriends.org/index.php?threads/tc-750-phono-pre-amp-continued.150/
A second "secret" is that the riaa filter is placed in a current feedback network being very fast.And this preamp also have a voltage feedback too...so i'd say it looks like a wisely elaborated one.
This "fairly wisely comunicated wisdom" is actually not that wide...i think that for a few years I'm the only preacher of this dusty theory here on diy audio although i picked it up a long time ago from another site of a very well known member of this forum .I didn't preached it because I believe it, but because I had it verified in the real wold on many preamplifiers until I actually internalized it as my own.
It might not be everyone experience...I can get it as thrre are countless phono preamps on Earth within very different setups ..it was my experience for sure though as i only listen to these preamps on headphones with pretty highsensitivity, undamped by cubic meters of air..
Truth is that my first phono preamp I ever listened was a tube one made by myself and tubes are very forgiving with high input transients too.High gm Jfet transistors aren't unless they are used with very low voltage gain or inside a circuit that behaves like a compressor or AGC.
https://www.superbestaudiofriends.org/index.php?threads/tc-750-phono-pre-amp-continued.150/