Keep the Black if you want.
buying very expensive Electrolytes.
Especially not for use in power supplies.
Expensive Polypropylens, yes. Especially in the signal rail.
But on the other hand,
You lose nothing in performance by wasting
your money
on Big Money Capacitance or Specially namned Resistances.
So of course he should keep them.
And those who "hears" the difference between Electrolytes
used in amplifiers, can stay happy.
There is no scientific evidence it effect the soundwaves.
But it obviously can effect your subjective listening experience.
When you know that you have bought and put a such cap into amp.
And that is what counts in the end. Be happy!
I just do not want to encourage guys here,
to spend money in vain.
In my opinion there is no reason.
/halo - knows the difference between objective facts
and subjective "facts"
In my opinion there is nothing to gain byjean-paul said:
buying very expensive Electrolytes.
Especially not for use in power supplies.
Expensive Polypropylens, yes. Especially in the signal rail.
But on the other hand,
You lose nothing in performance by wasting
your moneyon Big Money Capacitance or Specially namned Resistances.
So of course he should keep them.
And those who "hears" the difference between Electrolytes
used in amplifiers, can stay happy.
There is no scientific evidence it effect the soundwaves.
But it obviously can effect your subjective listening experience.
When you know that you have bought and put a such cap into amp.
And that is what counts in the end. Be happy!
I just do not want to encourage guys here,
to spend money in vain.
In my opinion there is no reason.
/halo - knows the difference between objective facts
and subjective "facts"
Halo, I really don't want to argue and I usually respect your opinion but in this case I think you don't hit the nail on the head.
I did a lot of experiments with all kinds of caps in the past and since I discovered the sonical qualities of BG they are my choice. As even my wife hears the difference there must be a real difference
The normal series are not that special but NX Hi Q really is the best I ever used.
To me ( and others probably ) the use of BG is a choice of building a good amp or a very good amp. Very simple isn't it ?
It is certainly not that I want to hear a difference because I bought them and they were expensive. If they wouldn't sound good I would remove them and use another brand/type.
Something else: I recently "overhauled" ( if that's the correct expression ) two old but very good Yamaha T80 tuners that were built in 1984. A type of tuner with a sound quality that is rare today.
Since caps of nearly 20 years old ( some were labeled 1981 )are not to be trusted I changed them for BCcomponents series 37 ( standard industry quality ).
BG is too expensive in this case. Almost 30 pieces. When I wanted to change them in the other tuner I ran out of them so I used series 135 ( LL, 105 degrees and low ESR ) that I had in stock.
I left the tuners on for a few hours and listened to both of them.
There was a big difference to my surprise. Before my work they were practically the same in sound. I thought that it was too early for a conclusion so I left them on for another day. The next day there was still a difference. I opened them again and searched for the differences. Then I saw that the one with the worse sound had the switched PSU series caps. Left for the shop and bought the standard series and soldered them in. The differences were gone and both tuners were practically the same.
Please don't think this is the case with all low ESR types ! I used Elna RJH and Nichicon SXE with good results. Had bad experiences in the past with PR series that made sound very dull too.
The output cap was a 4.7 uF 50 V bipolar which I first didn't change. After the tuners burned in I decided to change the caps for 2 pieces of paralled 2.2 uF Siemens MKT ( 5 mm pitch ). The magic was gone and sound was "metallic" in the high tones.
So now I ordered BG 4.7 N series and will try them. If they again bring back the magic as I expect they sure will be my default brand for the highest demanding applications.
\Jean-Paul- that asks himself what scientific evidence you want if you have a good pair of ears.
Hi,
I'm not halo, but in the last few years I must have tried about any premium "audio grade" Electrolytic capacitor, about each and every "audio grade" copuling Cap and many "audio grade" resistors. This OF COURSE includes BG's.
In most cases I find myself, strictly subjectively prefering high quality military/industrial parts as being less coloured. Adding BG's to any Amplifier I tried them in (SS, Valves, SE Valves) it gives the sound an unpleasant edge. One BG is enough. I like the NX-HiQ for specific low noise PSU applications (Clocks, PLL Loops) but prfer to avoid electrolytics at all if I can or use Elna Silmic for signal and Sanyo Os-Con for Digital rail applications.
Black Gates? Almost always - no thank you. Equally the various PIO Coupling Cap's I tried remind of wet blankets thrown over the speakers and many Foil & Film plastic types tend towards the BG "etched, edgy, unpleasant" sound.
Equally, neither Carbon Resistors nor premium metal films really sound neutral. Of course, knowing the various sonic attributes of the different parts can help to make the right choice of parts when building/modifying gear, like my recommendation of carbon composite resistors and metalised polycarbonate caps for solid state gear (like gainclones), but BG's in solid state gear that already tends towards leannesse and edginess? Not me. Try Elna Silmic instead for a much smoother, more relaxed sound while missing no detail.
Anyway, no given part is a "silver bullet" that always improves the equipment it is applied to, BG's are no exception.
Sayonara
jean-paul said:
I'm not halo, but in the last few years I must have tried about any premium "audio grade" Electrolytic capacitor, about each and every "audio grade" copuling Cap and many "audio grade" resistors. This OF COURSE includes BG's.
In most cases I find myself, strictly subjectively prefering high quality military/industrial parts as being less coloured. Adding BG's to any Amplifier I tried them in (SS, Valves, SE Valves) it gives the sound an unpleasant edge. One BG is enough. I like the NX-HiQ for specific low noise PSU applications (Clocks, PLL Loops) but prfer to avoid electrolytics at all if I can or use Elna Silmic for signal and Sanyo Os-Con for Digital rail applications.
Black Gates? Almost always - no thank you. Equally the various PIO Coupling Cap's I tried remind of wet blankets thrown over the speakers and many Foil & Film plastic types tend towards the BG "etched, edgy, unpleasant" sound.
Equally, neither Carbon Resistors nor premium metal films really sound neutral. Of course, knowing the various sonic attributes of the different parts can help to make the right choice of parts when building/modifying gear, like my recommendation of carbon composite resistors and metalised polycarbonate caps for solid state gear (like gainclones), but BG's in solid state gear that already tends towards leannesse and edginess? Not me. Try Elna Silmic instead for a much smoother, more relaxed sound while missing no detail.
Anyway, no given part is a "silver bullet" that always improves the equipment it is applied to, BG's are no exception.
Sayonara
Do you mean that you prefer Silmic over NX HiQ ? I agree on OSCON for digital although BG NX HiQ are prefered by me for digital also. OSCON in analog is ruining sound, nevertheless I see a lot of schematics that use them in the analog part of DAC's
However I will try Silmic again for a change. It can work refreshing to listen to something else once in a while.
Military grade parts are hard to obtain for most of us, I compare to normal electrolytics and for example Wima MKP 10 caps. NX HiQ wins in that cases. Although more difficult to obtain than heroin in my country BG is practically the only boutique brand one can obtain without having to order from abroad.
Agreed, neither is the trend to use S&B transformers in all gear as I remarked lately. It always is the combination that does it. In the case of BG I found that paralling them to existing caps is a failure.
Anyway the remark Halo made was not to use BG's in a Gainclone. I am sure BG gives good results here. And Silmics probably will also. And they will always be better than the standard brands too in this amp.
My non-inverting Gainclone will have Panasonic FC's probably because the price ( 15 Euro's a piece ) for standard BG 1000 uF 50 V is too high for my taste. I can afford it but it is a ridiculous price and the decadency to buy such parts confronts me with my own character. I like quality but when I realise there are people on this planet that know poverty I really can't give 15 Euro's for one cap when I can have another very-good-but-slightly-less-than-BG one for 3 Euro's. Must be that calvinistic background of the dutch I guess
First Prize for originality!
Hi Kuei Yang Wang,
Congratulations are in order here as you are the first person (certainly since the three threads on BGs which were thrashed to death since Xmas) to imply that *having tried BGs out for themelves*, they didn't like them.
Craig Buckingham has found some Jensens which he likes better, but for most of us the jury is still out on this one as we haven't made this comparison yet. Hopefully Peter Daniel will be next on the list, as he has some to try, and he likes BGs in some of his constructions.
Incidentally, Craig didn't say he didn't care for BGs, in fact in some earlier posts he raved about them, but he has stated this preference more recently.
From my own point of view, your findings are interesting, especially as the majority of *BG users* who have posted here seem to think that there is nothing to touch them in the electrolytics line.
Regards,
Hi Kuei Yang Wang,
Congratulations are in order here as you are the first person (certainly since the three threads on BGs which were thrashed to death since Xmas) to imply that *having tried BGs out for themelves*, they didn't like them.
Craig Buckingham has found some Jensens which he likes better, but for most of us the jury is still out on this one as we haven't made this comparison yet. Hopefully Peter Daniel will be next on the list, as he has some to try, and he likes BGs in some of his constructions.
Incidentally, Craig didn't say he didn't care for BGs, in fact in some earlier posts he raved about them, but he has stated this preference more recently.
From my own point of view, your findings are interesting, especially as the majority of *BG users* who have posted here seem to think that there is nothing to touch them in the electrolytics line.
Regards,
I imagine that everyone on this website wants to be able to build gear that sounds special, and audio-grade parts are certainly a quick and easy (albeit expensive) way to accomplish this goal. However, it appears that often audio-grade parts are used as a substitute for thoughtful, thorough engineering. If you wish to become a better designer (and I hope that everyone reading this wants to), rather than purchasing audio-grade parts, you will do better to purchase lots of electronic engineering texts, study them, think about the ramifications, and apply the principles to your own designs.
A professional photographer may carry a Leica or Nikon, but they should be able to take a great photo using just a Brownie camera. The same standards should be applied to audio designers. If you can make a wonderful-sounding amplifier using industrial-grade parts throughout, then, and only then, should you think about special-grade parts. These should be considered as icing on an already delicious cake, _not_ the cake itself.
Assuming that you have cleared the above criteria, you may still regard certain special-grade (ie, military or aerospace) parts as being essential to the type of sonic personality that you want your designs to convey. Nothing wrong with this.
When it comes to audio-grade parts, however, my overall sentiments go in a similar direction as Thorsten's. Like him, I have tried a ridiculous number of "audio grade" parts, including just about any capacitor and resistor that I could lay my hands on. My conclusion is that they certainly change the sound in a major way, but for that very reason, their colorations are usually too much to stomach (although there are occasional exceptions).
But at the end of the day, there are many people in this world, and each individual has different experiences, expectations, priorities and tastes, and I respect those differences. No single "solution" can satisfy or be right for everyone.
regards, jonathan carr
A professional photographer may carry a Leica or Nikon, but they should be able to take a great photo using just a Brownie camera. The same standards should be applied to audio designers. If you can make a wonderful-sounding amplifier using industrial-grade parts throughout, then, and only then, should you think about special-grade parts. These should be considered as icing on an already delicious cake, _not_ the cake itself.
Assuming that you have cleared the above criteria, you may still regard certain special-grade (ie, military or aerospace) parts as being essential to the type of sonic personality that you want your designs to convey. Nothing wrong with this.
When it comes to audio-grade parts, however, my overall sentiments go in a similar direction as Thorsten's. Like him, I have tried a ridiculous number of "audio grade" parts, including just about any capacitor and resistor that I could lay my hands on. My conclusion is that they certainly change the sound in a major way, but for that very reason, their colorations are usually too much to stomach (although there are occasional exceptions).
But at the end of the day, there are many people in this world, and each individual has different experiences, expectations, priorities and tastes, and I respect those differences. No single "solution" can satisfy or be right for everyone.
regards, jonathan carr
Of course no one will disagree with what you stated, Jonathan but in the case of this handfull of parts called Gainclone there is not much left to engineer. There are 2 major topologies with some minor ( but effective ) sub versions. Besides that most people here are no engineers but hobbyists and probably they don't even have a wish for engineering. Maybe they just want a good amp and just copy the given schematic without even wanting to think about it's exact working.
This amp has been engineered, a schematic is given and the builder are left no other options than :
1- quality of wiring, how it is done and how it is routed.
2- case quality ( as Peter Daniel showed us recently ).
3- quality of parts including power supply.
We are talking about 9 parts per channel maximum ! So the not-so-mechanically capable among us will stick to points 1 and 3.
It is a very good project for someone that want to start this hobby. The endresult when built according the old rules will be good and maybe better than discrete amps. I state maybe because I haven't built one ( yet ). This little amp has stirred up things a lot and even some of the ones that laughed most have built one out of curiousity.
The "audio grade" components are generally no better than good industrial quality parts. My experiences are from changing caps in already engineered ready made products.I am no audio designer and changing existing equipment is a challenge and it can give a great deal of insight when done with patience and a understanding of what you're doing.
Sometimes with good results and sometimes with very bad results. Just using brand X because everybody does so and because they are audio grade is not the way to go. Colorations of parts are a fact of life and picking the ultimate is a hard task and very time consuming. Maybe that's one of the things why there is a market for High End gear. Some of us don't draw the line that high and are simply satisfied with a better result than than they had before.
I make an exception for BG however. In this amp you can't go wrong by choosing BG instead of standard caps was the point I was trying to make.
regards,
Jean-Paul
>in the case of this handfull of parts called Gainclone there is not much left to engineer<
There are still things that can be done, even if you don't depart much from the Gainclone schematics. And if you are willing to design a new monolithic amplifier schematic, then you can go quite far indeed.
>1- quality of wiring, how it is done and how it is routed.<
Having put quite a bit of work into this area, I assure you that this can be a big one. Although the quality of wiring has some impact on the outcome (of course), the major gain comes in how the harness is designed and routed.
>3- quality of parts including power supply.<
How the power supply is designed can have a conclusive impact on your point 1. If the power supply is cleverly designed, the quality of the parts used has comparatively less impact. However, doing this may push you over the 9 parts per channel limit.
>Besides that most people here are no engineers but hobbyists and probably they don't even have a wish for engineering.<
I sincerely hope that you are wrong. Up to now, I have assumed that even if the readers on this website may not always have much knowledge or experience with electronic engineering, at least they have a strong desire to learn and become better. But if you are right and the vast majority of the readers here are simply looking for others to hand out ready-packaged information, without much desire to study, learn or think on their own, then for me to post on this website is a waste of time and server space.
>Maybe they just want a good amp and just copy the given schematic without even wanting to think about it's exact working.<
99.999% of the time, the desire for quality does not coexist easily on the same sheet of paper as the desire for intellectual laziness.
>I make an exception for BG however.<
While I respect the desire of others to use Black Gates, I have yet to experience any overwhelming urge to incorporate them into my own designs.
regards, jonathan carr
There are still things that can be done, even if you don't depart much from the Gainclone schematics. And if you are willing to design a new monolithic amplifier schematic, then you can go quite far indeed.
>1- quality of wiring, how it is done and how it is routed.<
Having put quite a bit of work into this area, I assure you that this can be a big one. Although the quality of wiring has some impact on the outcome (of course), the major gain comes in how the harness is designed and routed.
>3- quality of parts including power supply.<
How the power supply is designed can have a conclusive impact on your point 1. If the power supply is cleverly designed, the quality of the parts used has comparatively less impact. However, doing this may push you over the 9 parts per channel limit.
>Besides that most people here are no engineers but hobbyists and probably they don't even have a wish for engineering.<
I sincerely hope that you are wrong. Up to now, I have assumed that even if the readers on this website may not always have much knowledge or experience with electronic engineering, at least they have a strong desire to learn and become better. But if you are right and the vast majority of the readers here are simply looking for others to hand out ready-packaged information, without much desire to study, learn or think on their own, then for me to post on this website is a waste of time and server space.
>Maybe they just want a good amp and just copy the given schematic without even wanting to think about it's exact working.<
99.999% of the time, the desire for quality does not coexist easily on the same sheet of paper as the desire for intellectual laziness.
>I make an exception for BG however.<
While I respect the desire of others to use Black Gates, I have yet to experience any overwhelming urge to incorporate them into my own designs.
regards, jonathan carr
jcarr said:
I might be wrong here, but for me the best example of thoughtful and most simple engineering is a box containing a single series resistor. There is no substitute and possible improvement on that setup, but choosing the part which sonically matches best the rest of a system.
All subsequent enginnering is always variation and complication of that simple example.
... and a lot can be improved on Thorsten's gainclone design.
power supply: use common mode chokes between rectifier and reservoir caps, connect reservoir cap ground to loudspeaker ground rather than any place that may seem convenient, make sure signal ground does not carry any significant current
feedback resistors: I agree that the inverting configuration may have sonic benefits because it keeps the input transistors from performing any voltage swings. However, the impedances are so high that the circuit must be more vulnerable to EMI pickup and oscillations than it need be. Also, imbalances of the input capacitances or the feedback impedances might still cause some distortion, although this is much alleviated by the use of the inverting configuration.
I don't see the advantages of the particular choice of volume control topology, but I haven't yet put too much thought in this.
I have used the 3886 in non-inverting configuration with much lower (1.5k) balanced load impedances. I turned out I didn't even need the DC blocking cap in the feedback network.
A Zobel output load might be a good idea as I have observered that the LM3886 may start local oscillation of one output transistor if driving a low impedance load.
If somebody reports that some "Audio grade" parts cause a significant change in sound, this always has me worried. There are usually a couple of possibilities:
- The person wants to believe in the change. This might be the case especially with statements like: "The sonic signature of xy brand capacitor can be discerned no matter where in the CD player it is used.", "A single capacitor made all the difference."
- The audio grade parts are so bad (i.e. non-linear) that they actually leave some signature which may be perceived as good or bad.
- The design may be inadequate so that the part has a chance to make a difference. For example, in a power supply which has suboptimal wiring and no current limiting circuitry (resistors, inductors or common mode chokes) between rectifier and reservoir, a low ESR reservoir cap may result in sharper charging spikes that may find their way into the signal. A lower ESR (= lower quality) cap, audio grade or not, may rightfully be perceived as an improvement. However, if there is charge current limiting and the layout/wiring is done as to minimize shared ground impedance and magnetic coupling, a low ESR cap should actually sound better.
power supply: use common mode chokes between rectifier and reservoir caps, connect reservoir cap ground to loudspeaker ground rather than any place that may seem convenient, make sure signal ground does not carry any significant current
feedback resistors: I agree that the inverting configuration may have sonic benefits because it keeps the input transistors from performing any voltage swings. However, the impedances are so high that the circuit must be more vulnerable to EMI pickup and oscillations than it need be. Also, imbalances of the input capacitances or the feedback impedances might still cause some distortion, although this is much alleviated by the use of the inverting configuration.
I don't see the advantages of the particular choice of volume control topology, but I haven't yet put too much thought in this.
I have used the 3886 in non-inverting configuration with much lower (1.5k) balanced load impedances. I turned out I didn't even need the DC blocking cap in the feedback network.
A Zobel output load might be a good idea as I have observered that the LM3886 may start local oscillation of one output transistor if driving a low impedance load.
If somebody reports that some "Audio grade" parts cause a significant change in sound, this always has me worried. There are usually a couple of possibilities:
- The person wants to believe in the change. This might be the case especially with statements like: "The sonic signature of xy brand capacitor can be discerned no matter where in the CD player it is used.", "A single capacitor made all the difference."
- The audio grade parts are so bad (i.e. non-linear) that they actually leave some signature which may be perceived as good or bad.
- The design may be inadequate so that the part has a chance to make a difference. For example, in a power supply which has suboptimal wiring and no current limiting circuitry (resistors, inductors or common mode chokes) between rectifier and reservoir, a low ESR reservoir cap may result in sharper charging spikes that may find their way into the signal. A lower ESR (= lower quality) cap, audio grade or not, may rightfully be perceived as an improvement. However, if there is charge current limiting and the layout/wiring is done as to minimize shared ground impedance and magnetic coupling, a low ESR cap should actually sound better.
Hi,
This can be done, however if you have fully seperate transformers and windings for each voltage (as I imply in my comments on the gainclone board) this becomes much less of an issue and simplicity has it's own attractions.
What gives you the impression that I recommended anything else?
!!!???
The input impedance will be around 10k. This is much lower than most amplifiers, so I think teh reverse holds true. The marginal stability with a 100k linear volume control can be "fixed" with the added resistor described here. Oh and that balooney that has been bandied about "interconnect is part of the feedback path" is just an illustration how little the opration of aehh... operational amplifiers is understood in general.
Life is always full of surprises. You can never address all of them.
Then you obviously you never compared a same make log pot to one with linear law and law faking resistor, sonically I mean. I will not venture here much of a theory as to the why, yet I suspect that the varying composition of the resistance track for log pots (to get that log law) compared to the even and steady one with a linear law track is responsible for the observed sonic differences.
It does not worry me, as many issues have been documented in parts non-linearity, manetism (copperclad steel leads especially) and such. Some of these, while near measurement limits and often assumed "inaudible" based on incomplete undersatnding of the human auditory system (or plain unthinking orthodoxy), tend to be disproportionatly audible with music, due to their "dissonant" or "disconsonant" (for lack of better words) nature.
However many parts admittedly also tend to give subjectively "pleasant" (to some at least) effects.
Sayonara
This can be done, however if you have fully seperate transformers and windings for each voltage (as I imply in my comments on the gainclone board) this becomes much less of an issue and simplicity has it's own attractions.
What gives you the impression that I recommended anything else?
!!!???
The input impedance will be around 10k. This is much lower than most amplifiers, so I think teh reverse holds true. The marginal stability with a 100k linear volume control can be "fixed" with the added resistor described here. Oh and that balooney that has been bandied about "interconnect is part of the feedback path" is just an illustration how little the opration of aehh... operational amplifiers is understood in general.
Life is always full of surprises. You can never address all of them.
Then you obviously you never compared a same make log pot to one with linear law and law faking resistor, sonically I mean. I will not venture here much of a theory as to the why, yet I suspect that the varying composition of the resistance track for log pots (to get that log law) compared to the even and steady one with a linear law track is responsible for the observed sonic differences.
It does not worry me, as many issues have been documented in parts non-linearity, manetism (copperclad steel leads especially) and such. Some of these, while near measurement limits and often assumed "inaudible" based on incomplete undersatnding of the human auditory system (or plain unthinking orthodoxy), tend to be disproportionatly audible with music, due to their "dissonant" or "disconsonant" (for lack of better words) nature.
However many parts admittedly also tend to give subjectively "pleasant" (to some at least) effects.
Sayonara
>What gives you the impression that I recommended
>anything else?
Nothing, and I was not referring to your post. I just happen to have seen a few nasty examples on the web.
>The input impedance will be around 10k. This is
>much lower than most amplifiers, so I think teh
>reverse holds true.
I can see how the AC impedance on the inverting amp is around 10k if you assume the pot is used near zero. The noninverting input has 220 k for DC stability, which is AC shunted with 100 nF above about 10 Hz. So in the audio range we are faced with a variable impedance of >= 10k and close to 0R. This makes poor balance. By the way, most (non-inverting) designs I know of have impedances on the order of 1 k on both inputs, the low impedance on the noninverting input being delivered by the preamp or volume pot. A typical feedback network is 22 k / 1k which leaves you also at below 1 k on the non-inverting input.
>The marginal stability with a 100k linear volume
>control can be "fixed" with the added
>resistor described here. Oh and that balooney
>that has been bandied about "interconnect is
>part of the feedback path" is just an
>illustration how little the opration of aehh...
>operational amplifiers is understood in general.
What are you talking about???
>Then you obviously you never compared a same make
>log pot to one with linear law and law faking
>resistor, sonically I mean. I will not venture
>here much of a theory as to the why, yet I
>suspect that the varying composition of the
>resistance track for log pots (to get that log
>law) compared to the even and steady one with a
>linear law track is responsible for the observed
>sonic differences.
Ok, will read up on this. Best way though is probably a stepped attenuator.
>anything else?
Nothing, and I was not referring to your post. I just happen to have seen a few nasty examples on the web.
>The input impedance will be around 10k. This is
>much lower than most amplifiers, so I think teh
>reverse holds true.
I can see how the AC impedance on the inverting amp is around 10k if you assume the pot is used near zero. The noninverting input has 220 k for DC stability, which is AC shunted with 100 nF above about 10 Hz. So in the audio range we are faced with a variable impedance of >= 10k and close to 0R. This makes poor balance. By the way, most (non-inverting) designs I know of have impedances on the order of 1 k on both inputs, the low impedance on the noninverting input being delivered by the preamp or volume pot. A typical feedback network is 22 k / 1k which leaves you also at below 1 k on the non-inverting input.
>The marginal stability with a 100k linear volume
>control can be "fixed" with the added
>resistor described here. Oh and that balooney
>that has been bandied about "interconnect is
>part of the feedback path" is just an
>illustration how little the opration of aehh...
>operational amplifiers is understood in general.
What are you talking about???
>Then you obviously you never compared a same make
>log pot to one with linear law and law faking
>resistor, sonically I mean. I will not venture
>here much of a theory as to the why, yet I
>suspect that the varying composition of the
>resistance track for log pots (to get that log
>law) compared to the even and steady one with a
>linear law track is responsible for the observed
>sonic differences.
Ok, will read up on this. Best way though is probably a stepped attenuator.
Hi,
KYW is right here, and there has been some comment by myself and others in another current thread about both stepped attenuators (the best) and pots used with law-faking resistors, if you are interested.
Basically, with log pots, the track is usually made up of perhaps three different formulations of resistive material (carbon, or conductive plastic, or maybe cermet) because it is not easy to produce a gradual change in this material which is used for the tracks.
With a linear pot, the same material is used throughout the pot's track, so it avoids the 'discontinuity' (or jerky steps) of the log pot's operation, and, apart from this, the resultant sound quality will (generally) be rather better due to the 'single material' fabrication.
There is also another point in favour of using a law-faking resistor arrangement, in that I have found that the sound quality of such an arrangement is determined far more by the quality of the bypassing resistor, than the pot, itself.
Accordingly, you can end up with a quite good result (sonically) when using an 'average' pot but with a single good quality resistor.
Regards,
KYW is right here, and there has been some comment by myself and others in another current thread about both stepped attenuators (the best) and pots used with law-faking resistors, if you are interested.
Basically, with log pots, the track is usually made up of perhaps three different formulations of resistive material (carbon, or conductive plastic, or maybe cermet) because it is not easy to produce a gradual change in this material which is used for the tracks.
With a linear pot, the same material is used throughout the pot's track, so it avoids the 'discontinuity' (or jerky steps) of the log pot's operation, and, apart from this, the resultant sound quality will (generally) be rather better due to the 'single material' fabrication.
There is also another point in favour of using a law-faking resistor arrangement, in that I have found that the sound quality of such an arrangement is determined far more by the quality of the bypassing resistor, than the pot, itself.
Accordingly, you can end up with a quite good result (sonically) when using an 'average' pot but with a single good quality resistor.
Regards,
Hi!
Have you ever noticed the rantings of this oney guy about the LM3875 and the GainClones??
http://www.hilberink.nl/amps/lm3875schema.htm
He even links the "This is not just another GainClone"-thread.
I have to say that I understand some of the things he says (some stuff sounds right to me), but right now I tend to trust the rest of the people on this board more... I just was wondering how anyone could get so excited about a bunch of DIYers who use IC-OPs for building amps...
I understand the raving of R. Elliot about the original GainCard, but not this one fella...
Anyway, good afternoon ;-)
Arndt
Germany
Have you ever noticed the rantings of this oney guy about the LM3875 and the GainClones??
http://www.hilberink.nl/amps/lm3875schema.htm
He even links the "This is not just another GainClone"-thread.
I have to say that I understand some of the things he says (some stuff sounds right to me), but right now I tend to trust the rest of the people on this board more... I just was wondering how anyone could get so excited about a bunch of DIYers who use IC-OPs for building amps...
I understand the raving of R. Elliot about the original GainCard, but not this one fella...
Anyway, good afternoon ;-)
Arndt
Germany
Hi,
Ahh, sorry. I just noticed in one sentence "Thorstens gainclone design" and soon after recommendations to change the groundlayout....
Correction. With the 100k linear Pot AND the later suggested 22k "stabilising" resistor to ground on the inverting input the maximum AC Impedance seen on the Inverting input is around 12k7. In case of the volume fully turned up/down this becomes around 6k7. So if we place a 10k resistor to ground on the non-inverting input we will have minimised the Mismatch of AC impedances.
Without the added 22k Resistor the AC impedance on the inverting Pin varies from appx 10k to 30k, so if we want to minimise the mismatch adding a 22k Resistor in series with 1uF in parallel to 220k would be good if we use an input coupling capacitor. Without the input coupling capacitor using just a 22k Resistor will again minimise offset and mismatch.
However, given that the LM3875/3886 buffers the input differential pair with Emitter followers and at least in theory no voltage change happens on either input (inverting operation) the modulation of the base (input) current is absolutely minimised, making the AC Mismatch relatively irelevant.
Actually, if we assume a Noninverting Amplifier preceeded by a 50k Volume control and with a 1K/22k feedback loop the impedance seen by the inverting input will be around 956 Ohm. The impedance seen by the non0inverting input will vary from 0 ohm to 25kOhm. This does not strike me AT ALL as well balanced or low.
Of course, you may postulate driving from a low impedance source without intervening volume control. In this case the inverted circuit can have precision balanced impedances as easily as the non-inverting circuit.
Thus I fail to follow your argument
1) I am talking about the recent "inverted gainclone" revision that prescribes a 22k resistor to ground from the inverting input to ground and if a input coupling capacitor is used 18k to ground on the positive input, no parallel capacitor. This makes the 220k feedback resistor LM3875/3886 stable even without source or the 100k linear pot centered.
2) I have come across several claims that the FEEDBACK loop on the inverted gainclone includes the source and interconnect cable. It should not require any explanation as to why this is not so. The inverting input operates simply as near zero ohm currentsink, so the feedback loop is strictly limited to the feedback resistor.
Actually, purely based on subjective evaluation the "best" are in order:
Transformer based Attenuation
Good quality Cermet/Carbon track Linear Pot lawfaked
Single Series Resistor Single Shunt Resistor Attenuator
True "Ladder" Attenuator
Series Resistor Chain Attenuator
Good quality Cermet/Carbon Track Log Pot
Conductive Plastic Log Pot (linear w. Lawfaking not applicable due to distortion)
The preference for Cermet/Carbon is the same story as liking metal Film/Carbon Resistors, a choice, not a wrong/right.
Of course, the above reflects only my experience. I would no longer touch any of the Alps or Bourns conductive plastic pots, if you MUST use a decent quality log pot try Panasonics "for Audio" range, but even these are quite muddy compared to a lawfaked linear pot.
Sayonara
Ahh, sorry. I just noticed in one sentence "Thorstens gainclone design" and soon after recommendations to change the groundlayout....
Correction. With the 100k linear Pot AND the later suggested 22k "stabilising" resistor to ground on the inverting input the maximum AC Impedance seen on the Inverting input is around 12k7. In case of the volume fully turned up/down this becomes around 6k7. So if we place a 10k resistor to ground on the non-inverting input we will have minimised the Mismatch of AC impedances.
Without the added 22k Resistor the AC impedance on the inverting Pin varies from appx 10k to 30k, so if we want to minimise the mismatch adding a 22k Resistor in series with 1uF in parallel to 220k would be good if we use an input coupling capacitor. Without the input coupling capacitor using just a 22k Resistor will again minimise offset and mismatch.
However, given that the LM3875/3886 buffers the input differential pair with Emitter followers and at least in theory no voltage change happens on either input (inverting operation) the modulation of the base (input) current is absolutely minimised, making the AC Mismatch relatively irelevant.
Actually, if we assume a Noninverting Amplifier preceeded by a 50k Volume control and with a 1K/22k feedback loop the impedance seen by the inverting input will be around 956 Ohm. The impedance seen by the non0inverting input will vary from 0 ohm to 25kOhm. This does not strike me AT ALL as well balanced or low.
Of course, you may postulate driving from a low impedance source without intervening volume control. In this case the inverted circuit can have precision balanced impedances as easily as the non-inverting circuit.
Thus I fail to follow your argument
1) I am talking about the recent "inverted gainclone" revision that prescribes a 22k resistor to ground from the inverting input to ground and if a input coupling capacitor is used 18k to ground on the positive input, no parallel capacitor. This makes the 220k feedback resistor LM3875/3886 stable even without source or the 100k linear pot centered.
2) I have come across several claims that the FEEDBACK loop on the inverted gainclone includes the source and interconnect cable. It should not require any explanation as to why this is not so. The inverting input operates simply as near zero ohm currentsink, so the feedback loop is strictly limited to the feedback resistor.
Actually, purely based on subjective evaluation the "best" are in order:
Transformer based Attenuation
Good quality Cermet/Carbon track Linear Pot lawfaked
Single Series Resistor Single Shunt Resistor Attenuator
True "Ladder" Attenuator
Series Resistor Chain Attenuator
Good quality Cermet/Carbon Track Log Pot
Conductive Plastic Log Pot (linear w. Lawfaking not applicable due to distortion)
The preference for Cermet/Carbon is the same story as liking metal Film/Carbon Resistors, a choice, not a wrong/right.
Of course, the above reflects only my experience. I would no longer touch any of the Alps or Bourns conductive plastic pots, if you MUST use a decent quality log pot try Panasonics "for Audio" range, but even these are quite muddy compared to a lawfaked linear pot.
Sayonara
Kuei,
Thanks for the great explanation of the RC circuit on the non-inverted input. I usually get a lot of info from your posts, except when they get over my head , which brings me to my question:
Thanks for the great explanation of the RC circuit on the non-inverted input. I usually get a lot of info from your posts, except when they get over my head
, which brings me to my question:
What's "lawfaked" mean? I tried a couple of searches and could only discovered why its used and not what it is. Thanks in advance.
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