I´d be intrigued as well. More generally but maybe for tweaking.
If you think it´s worth opening separate thread, why not? Everybody needs a volume control.
You can put the link here.
Jens - who actually forgot in the meantime what´s in the A04. Was it a real Alps/fake Alps? Is that even known for sure? The smaller Alps are <2€ IIRC.
Ok, what follows is only applicable if your are using digital sources (DAC etc.) with integrated digital volume.
If, like Gilles or me you have both a digital source and say some analogue ones (turntable etc.) then you need an extra pot (or an ADC etc.) to cover the analogue part and a more complicated switch. We did it, but that's not the topic here. This is a budget amp and my bet is most use it with digital sources.
A bit of history… I have been looking into MUSES, attenuators, great pots etc. since ages. All these solutions cost a lot, say 3 figures in $, and often 4 figures if not DIY. Disproportionate for what it is IMHO, although the engineer in me loves these. In the past we had some excellent pots that could compete with the best, I am lucky to own since decades an original Black Alps and more recently a Tocos. Both do an excellent job. I have a test rig in which I can add a pot and adjust volume with a sonometer to compare pot's additional sonic signature. Compare it vs nothing and vs a pure fixed resistor network with excellent resistors and airwired (purest solution probably). That gave me the idea, known from attenuators, that top resistors networks (voltage divider set up) with excellent (or NO) switches are attractive...if you keep things reasonable.
On the other hand, a decade ago we tested similary the digital volume adjustment of an MDAC tuned by John Westlake, built around Sabre ESS9018. We would have loved that digital volume could enable us to get rid of all this volume attenuation bits sides digital. But sespite the claims, digital volume adjustement isn’t perfect and around -25dB on CDs we were starting to hear a very small drop in quality, something that increased the more we attenuated the signal digitaly while of course compensating it elsewhere to have the same overall volume to conduct our tests.
Moving on to today…As Gilles needed a DAC, we tested several and at the end dropped the SU-9 and purchased a D70S. Question was : how good would its digital volume work ? Response to our ears : absolutely perfectly until -30dB regardless the HD format, probably still perfectly until -35dB regardless the file resolution and from there on there is a very small quality drop depending on the file resolution that can finally be distinguished on CD formats from -40dB on. Still very small losses at -40dB, and then they go increasing. That’s quite a range and I thought that perhaps I could find a solution around a 2 or 3 position only switch (nearly perfect contact and cheap, a reduced enhenced attenuator) to adjust the entire range we needed combining digital and analogue volume adjustments, while retaining a remote control. That was our target.
If, like Gilles or me you have both a digital source and say some analogue ones (turntable etc.) then you need an extra pot (or an ADC etc.) to cover the analogue part and a more complicated switch. We did it, but that's not the topic here. This is a budget amp and my bet is most use it with digital sources.
A bit of history… I have been looking into MUSES, attenuators, great pots etc. since ages. All these solutions cost a lot, say 3 figures in $, and often 4 figures if not DIY. Disproportionate for what it is IMHO, although the engineer in me loves these. In the past we had some excellent pots that could compete with the best, I am lucky to own since decades an original Black Alps and more recently a Tocos. Both do an excellent job. I have a test rig in which I can add a pot and adjust volume with a sonometer to compare pot's additional sonic signature. Compare it vs nothing and vs a pure fixed resistor network with excellent resistors and airwired (purest solution probably). That gave me the idea, known from attenuators, that top resistors networks (voltage divider set up) with excellent (or NO) switches are attractive...if you keep things reasonable.
On the other hand, a decade ago we tested similary the digital volume adjustment of an MDAC tuned by John Westlake, built around Sabre ESS9018. We would have loved that digital volume could enable us to get rid of all this volume attenuation bits sides digital. But sespite the claims, digital volume adjustement isn’t perfect and around -25dB on CDs we were starting to hear a very small drop in quality, something that increased the more we attenuated the signal digitaly while of course compensating it elsewhere to have the same overall volume to conduct our tests.
Moving on to today…As Gilles needed a DAC, we tested several and at the end dropped the SU-9 and purchased a D70S. Question was : how good would its digital volume work ? Response to our ears : absolutely perfectly until -30dB regardless the HD format, probably still perfectly until -35dB regardless the file resolution and from there on there is a very small quality drop depending on the file resolution that can finally be distinguished on CD formats from -40dB on. Still very small losses at -40dB, and then they go increasing. That’s quite a range and I thought that perhaps I could find a solution around a 2 or 3 position only switch (nearly perfect contact and cheap, a reduced enhenced attenuator) to adjust the entire range we needed combining digital and analogue volume adjustments, while retaining a remote control. That was our target.
We did a lot of tests to find the right volume adjustment range and, whereas we wanted to adjust depending on the HIFI system gain and the efficiency of loudspeakers, I believe the solution we have is likely to be applicable in nearly every reasonable case, regardless the LS provided you have a standard 2V source ! If not, it could still be adjusted if needed, but from 85 to 98dB/W/m it should do the trick with this amp in this gain chain !
We found that a simple 2 position flickswitch, which is ensuring a nearly perfect contact (say 20mR resistance over hundreds of thousands of cycles) with a simple voltage divider resistor network would cover our needs. That means here position 1 being a direct line when you want party levels (position « no attenuation »), and a low gear when you are listening to usual music. We wanted Gilles not to have to stand up to switch between high and low gear all the time, so that the low gear enables in fact already acceptable levels on most materials but very quite classic. As said, we carried a lot of tests and we even developed a process to find out what attenuations was needed in what case...
The principal is very simple and not new! There is enough gain with a 2V source and the Aiyima to drive any reasonable LS that is suitable for the Aiyima. Without mod, the chain looks like this : source, Aiyima 50k pot, preamp/balancing stage with gain of 2 and then the usual chip amp with gain of 20dB. So every source sees attenuation (and a 50k impedance) before entering the first stage of the Aiyima. We will stick to that principal but be clever. We will remove the existing pot and have instead a simple non expensive 2 position attenuator that gives us 2 positions : No attenuation and -28dB attenuation. And we will go for high quality components (for 5$) while also moving « while at it » to 20k input impedance (as that’s enough but you can of course also chose 50k if you wish). From there on all the rest of the unit is untouched. We use a nearly perfect DPDT ON / (nothing) / ON switch, something with negligeable losses that works reliably for 100 of thousands of cycles… and that should be small enough to fit inside the casing. OK, you lose the round pot knob…
How does it work ? Position 1 of this simple switch is finaly NO attenuation. You are in loud party mod. From there on you can adjust/reduce the volume with your DAC. You could do so without any limit, but from a certain attenuation point on you would lose quality. So we just adjust with the DAC until -28dB, and from 0dB to -28dB we have a perfect sound quality. From there on we flick the switch, which brings us to normal mode, and that means that when our DAC is at 0dB (full volume) we have in fact -28dB attenuation in the system. Think of it like the good old MUTE function that muted a lot but not completely. That is the only time when you have to touch the Aiyima, to change bracket so to speak. From there on you can adjust the volume with your DAC, still by remote, say perfectly until whatever you ears can hear and depending on your DAC, probably -30dB at least. As you have -28dB perfect attenuation to start with, you end up with perfect -58dB attenuation… in practice make that probably perfect -65 to -70dB. And then? Do you really need a third position? Then, indeed, if you reduce further the volume on your DAC you will lose quality. Slightly to start with, but at that attenuation level you are playing so quite that you can’t really hear any sound degradation with your ears ! Remember, we are talking real dB here, not what displays sometimes show with figures without units. So you have covered your entire volume range with your DAC remote and you just have to stand up when wanting extremely loud party mode.
Now, we haven’t built this into the Aiyima but outside as we needed an extra pot for analogue plus we are driving 2 amps at the same time. But the components are IMHO small enough to fit inside the Aiyima (the switch sideways probably) where the pot board was (that needs to be dremeled out). If space is an issue, any quality switch (DPDT ON /ON) can do the job, they are some that are microswitches. Any quality resistor could also do the trick, we went for overkill and it doesn’t cost much more at the end. Attached is the schematic and the parts reference, leading to a -28dB attenuation that worked exactly as intented in practice. On the same slide you could also calculate « your brackets / attenuations » should you wish to. Keep in mind that you don’t have to start at 0 (very loud DAC output perhaps?) and that your DAC may have a different « perfect volume range » : listen to it, try its digital volume. Keep also in mind the beauty of this 2 position attenuator is the switch : nearly perfect for little money. If you need 3 brackets / position, there are still nice and affordable quality switches, but they aren’t likely to fit inside the unit and as us you may find out in practice you don’t need them, nor an expensive multi step attenuator.
We indeed thought that very efficient systems might want a range shift, first switch position not being 0dB but perhaps -10dB and second one say -40dB instead of -28dB. Gilles 96dB/m/W LS proved not, and that is quite efficient. The value we chose seem to make sense regardless the speakers and cover enough range, but you could play with it, the formula is quite simple.
How does it sound ? It sounds better than the Alps Blue, as expected, Gilles says +1.5 point. Gains are in bass, treble, airiness, integration, flow, microdetails. But said Alps Blue was already +1.5 points vs the existing pot, so at the end you get +3 points for less than 5$... and an perfect channel match/tracking even a very low volume (quite a problem with the original pot). Oh, and a remote volume control
Installation is quite simple. Once the pot board dremeled out, you have its 3 inputs (on the right hand side) with earth in the middle and channels the other 2, and the same at the exit of the pot on the left hand side. That’s where you need to insert our superpot. Schematic I attached is for 1 channel only, for you to get the idea. Quite straightforward: a simple voltage divider with only 2 resistors. Can’t be more simple : if you don’t get it, I can’t explain it any better, let someone else do it for you !
Enjoy music with this simple solution, that of course is not reiventing the wheel, but perhaps used differently here thank’s to today’s modern digital sources
Claude
We found that a simple 2 position flickswitch, which is ensuring a nearly perfect contact (say 20mR resistance over hundreds of thousands of cycles) with a simple voltage divider resistor network would cover our needs. That means here position 1 being a direct line when you want party levels (position « no attenuation »), and a low gear when you are listening to usual music. We wanted Gilles not to have to stand up to switch between high and low gear all the time, so that the low gear enables in fact already acceptable levels on most materials but very quite classic. As said, we carried a lot of tests and we even developed a process to find out what attenuations was needed in what case...
The principal is very simple and not new! There is enough gain with a 2V source and the Aiyima to drive any reasonable LS that is suitable for the Aiyima. Without mod, the chain looks like this : source, Aiyima 50k pot, preamp/balancing stage with gain of 2 and then the usual chip amp with gain of 20dB. So every source sees attenuation (and a 50k impedance) before entering the first stage of the Aiyima. We will stick to that principal but be clever. We will remove the existing pot and have instead a simple non expensive 2 position attenuator that gives us 2 positions : No attenuation and -28dB attenuation. And we will go for high quality components (for 5$) while also moving « while at it » to 20k input impedance (as that’s enough but you can of course also chose 50k if you wish). From there on all the rest of the unit is untouched. We use a nearly perfect DPDT ON / (nothing) / ON switch, something with negligeable losses that works reliably for 100 of thousands of cycles… and that should be small enough to fit inside the casing. OK, you lose the round pot knob…
How does it work ? Position 1 of this simple switch is finaly NO attenuation. You are in loud party mod. From there on you can adjust/reduce the volume with your DAC. You could do so without any limit, but from a certain attenuation point on you would lose quality. So we just adjust with the DAC until -28dB, and from 0dB to -28dB we have a perfect sound quality. From there on we flick the switch, which brings us to normal mode, and that means that when our DAC is at 0dB (full volume) we have in fact -28dB attenuation in the system. Think of it like the good old MUTE function that muted a lot but not completely. That is the only time when you have to touch the Aiyima, to change bracket so to speak. From there on you can adjust the volume with your DAC, still by remote, say perfectly until whatever you ears can hear and depending on your DAC, probably -30dB at least. As you have -28dB perfect attenuation to start with, you end up with perfect -58dB attenuation… in practice make that probably perfect -65 to -70dB. And then? Do you really need a third position? Then, indeed, if you reduce further the volume on your DAC you will lose quality. Slightly to start with, but at that attenuation level you are playing so quite that you can’t really hear any sound degradation with your ears ! Remember, we are talking real dB here, not what displays sometimes show with figures without units. So you have covered your entire volume range with your DAC remote and you just have to stand up when wanting extremely loud party mode.
Now, we haven’t built this into the Aiyima but outside as we needed an extra pot for analogue plus we are driving 2 amps at the same time. But the components are IMHO small enough to fit inside the Aiyima (the switch sideways probably) where the pot board was (that needs to be dremeled out). If space is an issue, any quality switch (DPDT ON /ON) can do the job, they are some that are microswitches. Any quality resistor could also do the trick, we went for overkill and it doesn’t cost much more at the end. Attached is the schematic and the parts reference, leading to a -28dB attenuation that worked exactly as intented in practice. On the same slide you could also calculate « your brackets / attenuations » should you wish to. Keep in mind that you don’t have to start at 0 (very loud DAC output perhaps?) and that your DAC may have a different « perfect volume range » : listen to it, try its digital volume. Keep also in mind the beauty of this 2 position attenuator is the switch : nearly perfect for little money. If you need 3 brackets / position, there are still nice and affordable quality switches, but they aren’t likely to fit inside the unit and as us you may find out in practice you don’t need them, nor an expensive multi step attenuator.
We indeed thought that very efficient systems might want a range shift, first switch position not being 0dB but perhaps -10dB and second one say -40dB instead of -28dB. Gilles 96dB/m/W LS proved not, and that is quite efficient. The value we chose seem to make sense regardless the speakers and cover enough range, but you could play with it, the formula is quite simple.
How does it sound ? It sounds better than the Alps Blue, as expected, Gilles says +1.5 point. Gains are in bass, treble, airiness, integration, flow, microdetails. But said Alps Blue was already +1.5 points vs the existing pot, so at the end you get +3 points for less than 5$... and an perfect channel match/tracking even a very low volume (quite a problem with the original pot). Oh, and a remote volume control
Installation is quite simple. Once the pot board dremeled out, you have its 3 inputs (on the right hand side) with earth in the middle and channels the other 2, and the same at the exit of the pot on the left hand side. That’s where you need to insert our superpot. Schematic I attached is for 1 channel only, for you to get the idea. Quite straightforward: a simple voltage divider with only 2 resistors. Can’t be more simple : if you don’t get it, I can’t explain it any better, let someone else do it for you !
Enjoy music with this simple solution, that of course is not reiventing the wheel, but perhaps used differently here thank’s to today’s modern digital sources
Claude
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Not a single feedback on my posts... and I hesitated to post...
Hmm, just for my very own understanding, is it because:
A) nothing new, this is something you had already in your mind or realised already
B) you need more time to digest it
C) not really interesting, you don't bother
D) else
Enjoy music
Claude
Hmm, just for my very own understanding, is it because:
A) nothing new, this is something you had already in your mind or realised already
B) you need more time to digest it
C) not really interesting, you don't bother
D) else
Enjoy music
Claude
Hi All ! As Claude said, we built his 'volume gearbox' outside the A04 box for different reasons (multi sources, bi-amp). But looking at pictures I took while tweaking the amps this winter, I'm wondering if such a switch (same kind as the power on/off one) could fit instead of the small pot (once removed with its board) and re-use the pot knob hole. There possibly is enough room there. Aside that, this is only 4 small resistors (2 by channel), very easy to fit !
Gilles.
Gilles.
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Thanks Claude for the write-up. I like your creative thinking.
It indeed makes sense if you have a digital source.
I don´t and my A04 is almost turned up as it follows an active crossover so I don´t suffer from imbalances L/R at low volume settings (sometimes the only drawback of a cheap pot). I could actually get completely rid of it but will leave the amp as is.
It sometimes surprises me that not more DIY-audiophiles think about their gain-structure.
Preamp follows power amp and then you have to attenuate it all again with superpots.
I think it should be possible to find small enough a DPDT. Just think about your settings before you move the lever or you´ll go full blast!
Gonna go now and smoke some super-pot ;-)
It indeed makes sense if you have a digital source.
I don´t and my A04 is almost turned up as it follows an active crossover so I don´t suffer from imbalances L/R at low volume settings (sometimes the only drawback of a cheap pot). I could actually get completely rid of it but will leave the amp as is.
It sometimes surprises me that not more DIY-audiophiles think about their gain-structure.
Preamp follows power amp and then you have to attenuate it all again with superpots.
I think it should be possible to find small enough a DPDT. Just think about your settings before you move the lever or you´ll go full blast!
Gonna go now and smoke some super-pot ;-)
E) your level of knowledge is far away from others and some (me included) don't understand anything about.
Hi! dani;
I tried op amp 1612, I think I prefer it to opa1656.
On the other hand .... It costs an arm.
On TI specs, despite its age, it is designed for pro audio,
Superb balance ... the cimballes resonate without this feeling of compression and the treble is magnificent
Hi Joensd,
Thanks for your kind feedback.
Your case is indeed very different. And BTW also very interesting, I like it!
I am completely with you re gain structure, having to deal with very different systems from 87dB/W/m and 96dB/W/m and trying to optimise for each it makes a massive difference to sound and money to optimise gain.
Good luck for all your projects
MFG
Claude
Thanks for your kind feedback.
Your case is indeed very different. And BTW also very interesting, I like it!
I am completely with you re gain structure, having to deal with very different systems from 87dB/W/m and 96dB/W/m and trying to optimise for each it makes a massive difference to sound and money to optimise gain.
Good luck for all your projects
MFG
Claude