Thanks guys for the gain clarification.
But how will paralleling triodes affect the sound? Doesn't Conrad Johnson do a lot of this type of design in their pre-amps?
Anyway my main question was about the replacement of tha passive RIAA component of the ecc83/ecc88 dc phono with the S&B 10k "canned" riaa module that I think Mr. Kuei Yan Wag is familiar with. So is it a simple drop in ?
Joe
But how will paralleling triodes affect the sound? Doesn't Conrad Johnson do a lot of this type of design in their pre-amps?
Anyway my main question was about the replacement of tha passive RIAA component of the ecc83/ecc88 dc phono with the S&B 10k "canned" riaa module that I think Mr. Kuei Yan Wag is familiar with. So is it a simple drop in ?
Joe
Konnichiwa,
I have already noted a NO for that, however your post prompted me to write a few short notes of how to approach making a phonostage with the 10K RIAA here:
Designing a Phonostage with the S&B 10K LCR RIAA Module
Sayonara
joe3rp said:
I have already noted a NO for that, however your post prompted me to write a few short notes of how to approach making a phonostage with the 10K RIAA here:
Designing a Phonostage with the S&B 10K LCR RIAA Module
Sayonara
Konnichiwa,
Apply the usual methode. Each stage receives a local "star" ground where the PSU Filtering capacitors and all other current loops drawing current around this stage are returned. So for example the RIAA "ground" is returned to the first stage star ground.
In fact, the best thing to do is to forget anything about "ground" and remember that ground is actually the Signal (return) shared with the Powersupply (return).
Bare solid fine silver wire, ideally goldplated in ovesized PTFE Sleeving, Litzwire from Nebraska Surplus, Enameled copper wire, in order of preference.
Any of three are quite cheap. Goldplated 0.2mm Silver Wire from wires.co.uk is around £ 5 for 10m with the PTFE sleeving costing around the same.
Sayonara
Kofi Annan said:
Apply the usual methode. Each stage receives a local "star" ground where the PSU Filtering capacitors and all other current loops drawing current around this stage are returned. So for example the RIAA "ground" is returned to the first stage star ground.
In fact, the best thing to do is to forget anything about "ground" and remember that ground is actually the Signal (return) shared with the Powersupply (return).
Kofi Annan said:
Bare solid fine silver wire, ideally goldplated in ovesized PTFE Sleeving, Litzwire from Nebraska Surplus, Enameled copper wire, in order of preference.
Any of three are quite cheap. Goldplated 0.2mm Silver Wire from wires.co.uk is around £ 5 for 10m with the PTFE sleeving costing around the same.
Sayonara
My implementation of Kuei Yang Wang's low-cost phono stage is still in it's infancy, the caps will probably improve and I have yet to install my preferred Jupiter's in the output position, at the moment they are in another phono stage.
I'm feeding the phono stage with a "Gyrorbe" SE, OL Encounter, Ortofon KB, TX103 stepups and the phono stage runs into a TX102 TVC. The PS is a based on a WAD PSU-II that is silicon rectified CLCRCRCRC.
I've perfromed a quick comparison of the phonostage with the Cornet2 and WAD Phono-II. All were using NOS tubes, mainly various Mullards.
The ECC83 / 12AX7 based WAD is a very "pleasant" performer but ultimately it's rather laid back. The Cornet2 is a much more upfront, indeed it some respects it presents almost a CD sound, which is not meant as an insult!
Thorsten's phono stage immediately sounds well balanced, possibly due to the ECC83 and ECC88/6922 etc being an excellent match.
The sound is fluid in the mid with no harsh elements, it is certainly more forgiving than the Cornet2. Bass and timing is easily the best of the bunch. There is an ease of presentation coupled with a bouncy sound and fluidity to the music that I reckon over time will mean this will be my 1st choice phono stage out of these 3.
Cheers,
Clive
I'm feeding the phono stage with a "Gyrorbe" SE, OL Encounter, Ortofon KB, TX103 stepups and the phono stage runs into a TX102 TVC. The PS is a based on a WAD PSU-II that is silicon rectified CLCRCRCRC.
I've perfromed a quick comparison of the phonostage with the Cornet2 and WAD Phono-II. All were using NOS tubes, mainly various Mullards.
The ECC83 / 12AX7 based WAD is a very "pleasant" performer but ultimately it's rather laid back. The Cornet2 is a much more upfront, indeed it some respects it presents almost a CD sound, which is not meant as an insult!
Thorsten's phono stage immediately sounds well balanced, possibly due to the ECC83 and ECC88/6922 etc being an excellent match.
The sound is fluid in the mid with no harsh elements, it is certainly more forgiving than the Cornet2. Bass and timing is easily the best of the bunch. There is an ease of presentation coupled with a bouncy sound and fluidity to the music that I reckon over time will mean this will be my 1st choice phono stage out of these 3.
Cheers,
Clive
Having spent a little more time with Thorstens low-cost phono stage I find it gets better the more I listen, it probably is getting better with time.
What I really mean is that the Hagerman Cornet2 is good and initially impressive, whereas Throrsten's unit becomes more impressive over time. My vinyl is sounding so good.....I know this is "value engineered" compared to the LCR circuit but it's damned good. Depth, control, articulation are all very good.
Currently I have CV4004 and CV2493 fitted. I'm surprised it is this good.
What I really mean is that the Hagerman Cornet2 is good and initially impressive, whereas Throrsten's unit becomes more impressive over time. My vinyl is sounding so good.....I know this is "value engineered" compared to the LCR circuit but it's damned good. Depth, control, articulation are all very good.
Currently I have CV4004 and CV2493 fitted. I'm surprised it is this good.
Thorsten's low-cost phono stage
Thank you Thorsten for this low-cost phono stage project, it really sounds absolutely great!
More I listen music using this stage; more I like it. It sounds better and better using my old Thorens 160BC, and makes me happy.
I did use 6N1P Russian tube (filament current is about 650 mA), because I don't have 6DJ8, and tube based +B PSU (EL86 as serial regulator, and ECC 83 error amplifier) I already had.
Filaments are feed from separated secondaries of mains transformer, rectified and well filtered just near the mains transformer, and then local (near the tubes) regulated using well known solid state LM7812 (ECC 83) and LM7806 (6N1P).
I feel that it helps making the sound less influenced by mains (5oHz) noise.
I would ask Thorsten opinions about (possible increasing cost) modifications of his marvellous low-cost phono stage:
-Using parallel sections of ECC83 on the input stage;
(Would make this stage less noisy, increasing input capacitance - quite positive fact for MM RIAA stage-, and increasing gm of first tube - positive fact, also);
-Using CCS on both tubes.
(it would make both tubes working with less distortion, amplification made mostly on their internal impendence parallel with the load, all stage will be less influenced by the PSU noise, and +B value could be around 100V, actually being 250V).
Mr. Thorsten I wish to thank you again for this phono project!
Warm regards,
BBB
Thank you Thorsten for this low-cost phono stage project, it really sounds absolutely great!
More I listen music using this stage; more I like it. It sounds better and better using my old Thorens 160BC, and makes me happy.
I did use 6N1P Russian tube (filament current is about 650 mA), because I don't have 6DJ8, and tube based +B PSU (EL86 as serial regulator, and ECC 83 error amplifier) I already had.
Filaments are feed from separated secondaries of mains transformer, rectified and well filtered just near the mains transformer, and then local (near the tubes) regulated using well known solid state LM7812 (ECC 83) and LM7806 (6N1P).
I feel that it helps making the sound less influenced by mains (5oHz) noise.
I would ask Thorsten opinions about (possible increasing cost) modifications of his marvellous low-cost phono stage:
-Using parallel sections of ECC83 on the input stage;
(Would make this stage less noisy, increasing input capacitance - quite positive fact for MM RIAA stage-, and increasing gm of first tube - positive fact, also);
-Using CCS on both tubes.
(it would make both tubes working with less distortion, amplification made mostly on their internal impendence parallel with the load, all stage will be less influenced by the PSU noise, and +B value could be around 100V, actually being 250V).
Mr. Thorsten I wish to thank you again for this phono project!
Warm regards,
BBB
Re: Thorsten's low-cost phono stage
Konnichiwa,
That will make the output impedance a little higher, otherwise you'll be fine.
The ECC83 is part of the RIAA (with the large value unbypassed cathode resistor, so any changes there and your RIAA response (Low frequencies) will be off. If you can re-tune it it would be easy to use two sections of the ECC83 in parallel.
If you use 51K load and 91K +B Dropper and seperate cathode resistors for the ECC83 sections you will probably need around 270K in the place of 215K for the RIAA EQ.
You can easily change the Output stage to CCS, the Input stage would (again) require the RIAA series resistor to be adjusted, this time downwards. As the input stage drops a lot of the +B Voltage anyway you could use a lower +B decoupling resistor for the first stage and leave it otherwise as is and add a CCS to the output stage. The input stage is pretty linear (at the voltages it is likel to see anyway) as is.
Sayonara
Konnichiwa,
bucurb said:
That will make the output impedance a little higher, otherwise you'll be fine.
bucurb said:
The ECC83 is part of the RIAA (with the large value unbypassed cathode resistor, so any changes there and your RIAA response (Low frequencies) will be off. If you can re-tune it it would be easy to use two sections of the ECC83 in parallel.
If you use 51K load and 91K +B Dropper and seperate cathode resistors for the ECC83 sections you will probably need around 270K in the place of 215K for the RIAA EQ.
bucurb said:
You can easily change the Output stage to CCS, the Input stage would (again) require the RIAA series resistor to be adjusted, this time downwards. As the input stage drops a lot of the +B Voltage anyway you could use a lower +B decoupling resistor for the first stage and leave it otherwise as is and add a CCS to the output stage. The input stage is pretty linear (at the voltages it is likel to see anyway) as is.
Sayonara
Hallo Thorsten,
My version of this phono stage is humming excessively. I was wondering how the DC supply for the filaments should be best grounded...? And the chassis? I have a iron chassis for a change... and am no sure if I should connect that as well to the psu earth.
Right now the ECC88 centre pin gets connected to the PSU ground. (The center pin is a sort of star ground for the cathode resistors which have a lot of current flowing through it) From there a silver bus wire to the ECC83... Input ground is close to the ECC83 and output ground is connected near the ECC88 also on the silver bus wire.
As is often the case the B+ has no ripple but after the CCS (15mA) there is major ripple visible on the scope.
Thanks very much in advance!
Regards,
Bas
My version of this phono stage is humming excessively. I was wondering how the DC supply for the filaments should be best grounded...? And the chassis? I have a iron chassis for a change... and am no sure if I should connect that as well to the psu earth.
Right now the ECC88 centre pin gets connected to the PSU ground. (The center pin is a sort of star ground for the cathode resistors which have a lot of current flowing through it) From there a silver bus wire to the ECC83... Input ground is close to the ECC83 and output ground is connected near the ECC88 also on the silver bus wire.
As is often the case the B+ has no ripple but after the CCS (15mA) there is major ripple visible on the scope.
Thanks very much in advance!
Regards,
Bas
I am coming into this thread VERY late, after a wealth of information has already been posted. However, having also built I don't know how many RIAA stages over half a century, I hope to be endured for a few general observations. (I am writing from memory and a few notes; too many posts to try to snip):
1. I must have been a singularly lucky dude to have been able to get by without very fancy power supplies. If I am not mistaken we are working in class A, which means that a load as low as an RIAA pre-amp will not form anything of a variable load. Rather my problem was to be able to isolate the pre-amp from the rest especially at below 100 Hz where the gain is most. I never had any problems the moment I used a separate power supply - and some of my designs fed a 2mV pick-up into a 150W amplifier. I found the use of dc (well-filtered!!) on heaters a more lucrative investment.
2. I would strongly echo someone's thoughts early in the discussion on attenuating at sub-audio frequencies. My circuits were mostly feedback affairs, where just by proportioning coupling time constants that were there anyway, a handy 14 dB/octave cut-off below say 25 Hz could be achieved. With 3 such constants it is easy to get 20 dB/octave. I considered this much more important than fancy power supplies (with due respect for those who found them handy). Not only is it a good rumble filter, but as someone said, it is not funny to see your expensive loudspeaker cone leaving its frame just because you bumped something.
3. I have found the use of grid leak bias in any but a low gm sharp cut-off tube (say ECC83) a distortion generator, especially when fed from a relatively high impedance circuit like a passive RIAA. Admittedly the signal level is low here, but at +20 dB peaks (which is posible with some recordings!) this will count. When one considers some of the special components mentioned here to get better performance, I personally would not compromise by using a grid leak bias with an ECC88.
4. Then I am not sold on RIAA accuracy needing precision components to reach <0.5 dB accuracy etc. Such deviations will not be audible, and considering the whole set-up where the loudspeaker response alone can vary by several dB, let alone room acoustics, it is in my humble opinion a little over the top. In fact, I normally over-compensate below 70 Hz to 40 Hz by a few dB, because everything else usually start tapering off there.
It makes for a nice deep-bass effect (but don't overdo it).
5. The nominal 50K load resistor for a pick-up is - well, just nominal! A good way of attenuating treble according to RIAA is in fact to feed the pick-up into a lower resistor, say 10K. But for accuracy here one needs to know pick-up characteristics or have a frequency record. It differs from head to head; some may need a little C as someone suggested.
Just a few side thoughts, for what they are worth.
1. I must have been a singularly lucky dude to have been able to get by without very fancy power supplies. If I am not mistaken we are working in class A, which means that a load as low as an RIAA pre-amp will not form anything of a variable load. Rather my problem was to be able to isolate the pre-amp from the rest especially at below 100 Hz where the gain is most. I never had any problems the moment I used a separate power supply - and some of my designs fed a 2mV pick-up into a 150W amplifier. I found the use of dc (well-filtered!!) on heaters a more lucrative investment.
2. I would strongly echo someone's thoughts early in the discussion on attenuating at sub-audio frequencies. My circuits were mostly feedback affairs, where just by proportioning coupling time constants that were there anyway, a handy 14 dB/octave cut-off below say 25 Hz could be achieved. With 3 such constants it is easy to get 20 dB/octave. I considered this much more important than fancy power supplies (with due respect for those who found them handy). Not only is it a good rumble filter, but as someone said, it is not funny to see your expensive loudspeaker cone leaving its frame just because you bumped something.
3. I have found the use of grid leak bias in any but a low gm sharp cut-off tube (say ECC83) a distortion generator, especially when fed from a relatively high impedance circuit like a passive RIAA. Admittedly the signal level is low here, but at +20 dB peaks (which is posible with some recordings!) this will count. When one considers some of the special components mentioned here to get better performance, I personally would not compromise by using a grid leak bias with an ECC88.
4. Then I am not sold on RIAA accuracy needing precision components to reach <0.5 dB accuracy etc. Such deviations will not be audible, and considering the whole set-up where the loudspeaker response alone can vary by several dB, let alone room acoustics, it is in my humble opinion a little over the top. In fact, I normally over-compensate below 70 Hz to 40 Hz by a few dB, because everything else usually start tapering off there.
It makes for a nice deep-bass effect (but don't overdo it).
5. The nominal 50K load resistor for a pick-up is - well, just nominal! A good way of attenuating treble according to RIAA is in fact to feed the pick-up into a lower resistor, say 10K. But for accuracy here one needs to know pick-up characteristics or have a frequency record. It differs from head to head; some may need a little C as someone suggested.
Just a few side thoughts, for what they are worth.
Konnichiwa,
NFB increases PSRR. Consider a Circuit with very little PSRR and no NFB.
I would strongly advise against. Speakers usually already have well enough LF group delay to cause audible problems, no point excebarating it in a phonostage, especially not if you can ge a turntable that does not rumble and that does support the well and makes sure it is quite flat.
One may have the occasionally exceedingly warped record that causes problems, in such cases a switchable HPF may be preferable, but it should NEVER be designed into a quality phono stage without bypass option.
First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S.
Secondly, I found that in this specific circuit the normal signal (0db) on the final stage grid is only around 15mV, with the maximum signal being 75mV. The "contact bias" system develops around 0.5V static bias (no signal) in this particular circuit. I found a rather substantiative absence of distortion at any normally expected signal levels and well past.
When one considers the absence of observable problems due to grid leak bias and the problems added by using other means of bias (cathode bypass capacitor) it seems gridleak is not a "compromise", but rather a bonus.
Neither am I.
It will also excebarate any very low frequency noise, which might explain partially the need for steep highpass filters.
Indeed, just a few thoghts back, fwtaw.
And you should really try one of these days a non nfb Phono and even gridleak/contact bias. You might be surprised. I have done it the other way many times as well.
Sayonara
Johan Potgieter said:
NFB increases PSRR. Consider a Circuit with very little PSRR and no NFB.
Johan Potgieter said:
I would strongly advise against. Speakers usually already have well enough LF group delay to cause audible problems, no point excebarating it in a phonostage, especially not if you can ge a turntable that does not rumble and that does support the well and makes sure it is quite flat.
One may have the occasionally exceedingly warped record that causes problems, in such cases a switchable HPF may be preferable, but it should NEVER be designed into a quality phono stage without bypass option.
Johan Potgieter said:
First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S.
Secondly, I found that in this specific circuit the normal signal (0db) on the final stage grid is only around 15mV, with the maximum signal being 75mV. The "contact bias" system develops around 0.5V static bias (no signal) in this particular circuit. I found a rather substantiative absence of distortion at any normally expected signal levels and well past.
Johan Potgieter said:
When one considers the absence of observable problems due to grid leak bias and the problems added by using other means of bias (cathode bypass capacitor) it seems gridleak is not a "compromise", but rather a bonus.
Johan Potgieter said:
Neither am I.
Johan Potgieter said:
It will also excebarate any very low frequency noise, which might explain partially the need for steep highpass filters.
Johan Potgieter said:
Indeed, just a few thoghts back, fwtaw.
And you should really try one of these days a non nfb Phono and even gridleak/contact bias. You might be surprised. I have done it the other way many times as well.
Sayonara
Three short comments:
"Consider a Circuit with very little PSRR and no NFB."
Why? It is possible to design excellent circuits with high PSRR, negative feedback or no.
"First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S. "
It's the stuff that's not intentional which is the problem. Real-world LPs often have very high level ticks and pops which can be dealt with effortlessly- or cause a preamp to choke for some milliseconds after, just to make the overload more annoying and noticeable. IME, this is the single greatest difference among decent phono stages; they can make ticks'n'pops very annoying or let you listen through them effortlessly.
And finally, subsonic noise can have more sources than just warps- a LOT of records do not have perfect center holes.
"Consider a Circuit with very little PSRR and no NFB."
Why? It is possible to design excellent circuits with high PSRR, negative feedback or no.
"First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S. "
It's the stuff that's not intentional which is the problem. Real-world LPs often have very high level ticks and pops which can be dealt with effortlessly- or cause a preamp to choke for some milliseconds after, just to make the overload more annoying and noticeable. IME, this is the single greatest difference among decent phono stages; they can make ticks'n'pops very annoying or let you listen through them effortlessly.
And finally, subsonic noise can have more sources than just warps- a LOT of records do not have perfect center holes.
Konnichiwa,
True, but it is eaqually easy to make a PSU that is dead quiet simply and cheaply, so why bother adding all that complication.
"First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S. "
Yes, this tends to be the problem for NFB Eq'ed stages.
The specific design discussed has well over 30db overload margin on a 5mV input, which is more than enough for that.
The excentric centerhole causes 1.8Hz stuff, as does usually record warp. Even my "fairly flat at 20Hz" phonostage has a good deal of attenuation that far down.
Sayonara
SY said:
True, but it is eaqually easy to make a PSU that is dead quiet simply and cheaply, so why bother adding all that complication.
"First, no cartridge I ever had tracked +16db ref. 5cm/S @ 300Hz cleanly and the LP standards prescrive =14db re. 5cm/S. "
SY said:
Yes, this tends to be the problem for NFB Eq'ed stages.
The specific design discussed has well over 30db overload margin on a 5mV input, which is more than enough for that.
SY said:
The excentric centerhole causes 1.8Hz stuff, as does usually record warp. Even my "fairly flat at 20Hz" phonostage has a good deal of attenuation that far down.
Sayonara
K-Y-W (post #115):
Points taken with respect, as were your usual earlier posts.
We appear to have had different experiences. As for group-delay effects, acknowledged; but to my experience there is far more of that and well into the lower audible band (or not) from loudpseaker design than from a properly designed subsonic filter. One can compare phase effects of various approaches on Spice.
Yes, a "better" turntable. But it is difficult to convince a customer to pay a 4-figure amount extra for the same audible gain achieved rumble-wise by just a few extra $ worth (or none) of components (but disregarding other possible advantages of exotic turntables).
My comments regarding grid-leak bias was general. I have used it on low-impedance fed ECC83s and EF86s, but found a measurable difference in performance compared when used with less sharp cut-off tubes, back in the days when I was priviledged to work for a top research organisation where expensive spectrum analysers were available. (Sadly no longer; retired now and such exotics have become nice-to-have's.)
There is witness that your circuit performs excellently - so be it; I am glad. Again our approaches are simply different. E.g. I am not that biased against the use of the right kind of bypass capacitor (sacrilege!); we use electrolytics in power supplies where they are also in the signal circuit. In an excellent series of articles about 6 years ago in Electronics World, Cyril Bateman investigated capacitors over the spectrum; he found that bi-polars peformed very acceptably, with graphs to prove.
As for "trying a non-nfb phono stage and grid-leak bias one of these days and being surprised..." I have tried all and explained my reasons for certain preferences. I am saddened by my inability to convey that my experiences did come over decades, they were not merely blinkered recent fixations. Also my customers appeared to have been quite satisfied (some were musicians). In that sense not too many surprises for me, but let us allow for our different approaches. I distinctly hope though that I will never cease to find surprises - I cannot imagine a more dull life! (Or, woe of woes - a greater sign of old age.)
Thanks for your comments.
Points taken with respect, as were your usual earlier posts.
We appear to have had different experiences. As for group-delay effects, acknowledged; but to my experience there is far more of that and well into the lower audible band (or not) from loudpseaker design than from a properly designed subsonic filter. One can compare phase effects of various approaches on Spice.
Yes, a "better" turntable. But it is difficult to convince a customer to pay a 4-figure amount extra for the same audible gain achieved rumble-wise by just a few extra $ worth (or none) of components (but disregarding other possible advantages of exotic turntables).
My comments regarding grid-leak bias was general. I have used it on low-impedance fed ECC83s and EF86s, but found a measurable difference in performance compared when used with less sharp cut-off tubes, back in the days when I was priviledged to work for a top research organisation where expensive spectrum analysers were available. (Sadly no longer; retired now and such exotics have become nice-to-have's.)
There is witness that your circuit performs excellently - so be it; I am glad. Again our approaches are simply different. E.g. I am not that biased against the use of the right kind of bypass capacitor (sacrilege!); we use electrolytics in power supplies where they are also in the signal circuit. In an excellent series of articles about 6 years ago in Electronics World, Cyril Bateman investigated capacitors over the spectrum; he found that bi-polars peformed very acceptably, with graphs to prove.
As for "trying a non-nfb phono stage and grid-leak bias one of these days and being surprised..." I have tried all and explained my reasons for certain preferences. I am saddened by my inability to convey that my experiences did come over decades, they were not merely blinkered recent fixations. Also my customers appeared to have been quite satisfied (some were musicians). In that sense not too many surprises for me, but let us allow for our different approaches. I distinctly hope though that I will never cease to find surprises - I cannot imagine a more dull life! (Or, woe of woes - a greater sign of old age.)
Thanks for your comments.
Konnichiwa,
I do not know what sort of speakers you are used to, they may explain the difference in experience. In my case you find that I tend to prefer systems with a well above average efficiency and high resolution, plus they tend to be impulse coherent or at least nearly so (wideband "fullrange" systems, tannoy coaxials where necesary with sealed subs extnding the LF). Conventional so called "High Fidelity" Speakers (they are all but any fidelity) will give very different results.
A "better turntable" is not neccesarily extremely expensive and the benefits extend considerably past rumble and other VLF noise.
Well, any decent laptop (or desktop) PC with AC97 audio can be easily turned into a pretty decent FFT with > 80db dynamic range and if you build a 1KHz notchfilter plus amplifier you can get at least 20-40db more range.
I will not dispute that distortion maybe a little higher with gridleak bias at high levels, but at operational levels (which is all that interrests me) distortion in my circuit is low enough (and only very low order) that together with the distortion from LP & Cartridge we are well in the real of academic differences.
Well, having done quite extensive testing I do not use Electrolytics anywhere if I can. In the powersupply at the very least the final filter section capacitor (which is the one that is actually in the signal circuit - earlier stages tend to be insulated by the divider formed by the series impedance vs the final capacitors impedance) in my use is ALLWAYS a film type capacitor.
I agree that one may very well use a bypassed cathode resistor, but 100uF/35V rubycon metalised polypropylene capacitors are first a major PITA to get hold off at all (you need to get them from shops that only speak japanese) and they cost over 50 bucks a throw, plus the rippoff from your credit card company on the exchange rate, shipping and import taxes and duties.
I think the key differences between us are that you view everything in the context of commercial HiFi while I reject such mediocrity all across the board and hence do not concern myself with designs that fit into this context (not strictly true, I actually got against better knowledge and judgement involved again in designing commercial audio gear, but my commercial stuff is nothing like my DIY Designs, simply because they are meant to sell first and perform second).
I will suggest again that if you find the time you try building a copy of the "el cheapo", including the suggested valve rectified RC filtered supply and try to have a good listen, using a system with proper studio grade monitor speakers (or Quad ESL's at a pinch) and decent Valve Amp's (preferably triode, low/no NFB).
Please do not bother with common HiFi stuff as ancillaries. When designing while using them, you do you invariably design the mediocricy of the ancililaries into your gear and when auditioning other stuff you fail to notice even quite significant differences. Most common "HiFi Speakers" are great equalisers, they make everything sound equally bad by their own severe limitations in fidelity.
To me DIY was always about creating what you could not more or less readily buy but wanted anyway (this often involves a variety of techniques and features not commonly employed in commercial gear), not as a way to save a few bucks by copying generic commercial gear (better off working a few weeks heavy overtime and buying the commercial unit me sez).
Sayonara
Johan Potgieter said:
I do not know what sort of speakers you are used to, they may explain the difference in experience. In my case you find that I tend to prefer systems with a well above average efficiency and high resolution, plus they tend to be impulse coherent or at least nearly so (wideband "fullrange" systems, tannoy coaxials where necesary with sealed subs extnding the LF). Conventional so called "High Fidelity" Speakers (they are all but any fidelity) will give very different results.
Johan Potgieter said:
A "better turntable" is not neccesarily extremely expensive and the benefits extend considerably past rumble and other VLF noise.
Johan Potgieter said:
Well, any decent laptop (or desktop) PC with AC97 audio can be easily turned into a pretty decent FFT with > 80db dynamic range and if you build a 1KHz notchfilter plus amplifier you can get at least 20-40db more range.
I will not dispute that distortion maybe a little higher with gridleak bias at high levels, but at operational levels (which is all that interrests me) distortion in my circuit is low enough (and only very low order) that together with the distortion from LP & Cartridge we are well in the real of academic differences.
Johan Potgieter said:
Well, having done quite extensive testing I do not use Electrolytics anywhere if I can. In the powersupply at the very least the final filter section capacitor (which is the one that is actually in the signal circuit - earlier stages tend to be insulated by the divider formed by the series impedance vs the final capacitors impedance) in my use is ALLWAYS a film type capacitor.
I agree that one may very well use a bypassed cathode resistor, but 100uF/35V rubycon metalised polypropylene capacitors are first a major PITA to get hold off at all (you need to get them from shops that only speak japanese) and they cost over 50 bucks a throw, plus the rippoff from your credit card company on the exchange rate, shipping and import taxes and duties.
I think the key differences between us are that you view everything in the context of commercial HiFi while I reject such mediocrity all across the board and hence do not concern myself with designs that fit into this context (not strictly true, I actually got against better knowledge and judgement involved again in designing commercial audio gear, but my commercial stuff is nothing like my DIY Designs, simply because they are meant to sell first and perform second).
I will suggest again that if you find the time you try building a copy of the "el cheapo", including the suggested valve rectified RC filtered supply and try to have a good listen, using a system with proper studio grade monitor speakers (or Quad ESL's at a pinch) and decent Valve Amp's (preferably triode, low/no NFB).
Please do not bother with common HiFi stuff as ancillaries. When designing while using them, you do you invariably design the mediocricy of the ancililaries into your gear and when auditioning other stuff you fail to notice even quite significant differences. Most common "HiFi Speakers" are great equalisers, they make everything sound equally bad by their own severe limitations in fidelity.
To me DIY was always about creating what you could not more or less readily buy but wanted anyway (this often involves a variety of techniques and features not commonly employed in commercial gear), not as a way to save a few bucks by copying generic commercial gear (better off working a few weeks heavy overtime and buying the commercial unit me sez).
Sayonara
