Regulation need not be complex. A resistor/Zener pair to set the reference voltage and a pass device will get you started. Even softer is a resistive divider, but that won't lock the voltage.
The next step is to use a differential to compare the reference voltage to the output voltage. Still not much of a problem. Add a cap or two to smooth the reference further. Still not too bad.
It's when you start massaging the references with current sources and such that the regulator starts looking more like sphagetti. Slow start add-ons and short circuit protection come sneaking in the back door and suddenly you have a dedicated amp on your hands--one designed to current-amplify a high-purity DC signal generated within the amplifier circuitry itself. It's kinda neat, really. I mean, you think you're a hardware nut? Not until you've got a separate chassis for the power supply and regulation.
Man, I'm starting to breathe heavy just thinking about it. Someone start dragging out the heavy iron. I need a fix.
There's no question that regulators can get complex, but they can also improve the sound greatly.
The problem, at least for power amplifiers, is that they will need their own heat sinks and create a decent amount of heat. That, in turn, makes the circuit heavier and more expensive.
Fortunately, you don't have to go to those extremes in order to begin seeing some benefit.
Grey
The next step is to use a differential to compare the reference voltage to the output voltage. Still not much of a problem. Add a cap or two to smooth the reference further. Still not too bad.
It's when you start massaging the references with current sources and such that the regulator starts looking more like sphagetti. Slow start add-ons and short circuit protection come sneaking in the back door and suddenly you have a dedicated amp on your hands--one designed to current-amplify a high-purity DC signal generated within the amplifier circuitry itself. It's kinda neat, really. I mean, you think you're a hardware nut? Not until you've got a separate chassis for the power supply and regulation.
Man, I'm starting to breathe heavy just thinking about it. Someone start dragging out the heavy iron. I need a fix.
There's no question that regulators can get complex, but they can also improve the sound greatly.
The problem, at least for power amplifiers, is that they will need their own heat sinks and create a decent amount of heat. That, in turn, makes the circuit heavier and more expensive.
Fortunately, you don't have to go to those extremes in order to begin seeing some benefit.
Grey
Not quite, but close. I like to use separate subchassis for PSU and the rest, and then put them in one big chassis, star grounding all chassis. But I've not built a power amp yet, so I'm talking about smaller equipment. For a power amp I'll probably omit the overall enclosure. One thing that's a problem is the thickness of the power interconnect (unless I have a large capacitance on the amp side, so then it acts like another RC filter section, but then the regulator has to be on the amp side).
So what would be a good approach if I wanted to go a bit beyond just pi filters on the PSU for an Aleph-X? If I go to the trouble of regulating, would I need to use a complex regulator to make a difference, or would a simple one work good too?
One time I used an old power amp through a step-up transformer to generate the AC power for a DAC and headphone amp. I think the setup sounded better when the frequency was around 100 Hz rather than 60...
Actually, using a higher line frequency to get better sound is not so surprising. Given that it pushes the ripple higher in frequency, the power supply filter would be more efficient in removing it. That said, there are limits to how far you can push the frequency without taking a look at the power supply design itself.
Two other points are involved:
--The amplifier serves as a filter for bad things coming in.
--The amplifier serves as a filter for bad things going out. Anything that spews as much RF as a digital circuit can easily influence how the rest of the system sounds. Keeping the RF out of the main AC is a huge benefit. Even something as an isolation transformer can work wonders in this case.
Grey
Two other points are involved:
--The amplifier serves as a filter for bad things coming in.
--The amplifier serves as a filter for bad things going out. Anything that spews as much RF as a digital circuit can easily influence how the rest of the system sounds. Keeping the RF out of the main AC is a huge benefit. Even something as an isolation transformer can work wonders in this case.
Grey
Grey,
Your post on how far you can take a regulator reminds me of another downside to modelling/simulation software, the fact that you can test whatever you want without spending a single cent. I started a little design project a few months ago to create a high current regulation circuit for a power amp. The development path you describe is exactly what I did in spice, started with a voltage follower, changed it to a differential, started adding CCS's, then darlingtoned the pass transistors, then realized that it would work fine as long it never had to turn on, etc. In the end, I had wasted literally weeks of time refining a regulator design that became more costly and complex than the amp it was to power. One day I finally recognized my lunacy and realized that it was far too expensive and complex to justify in reality, and scrapped it. If I would have had to build and test the thing, it never would have got that far out of hand.
Cheers, Terry
EDIT: Oh yeah, I was going to mention that I 100% agree with you on the big wad of capacitance after the regulators. In the development of my Zen headphone amp the biggest improvement that resulted from a single parts change was when I added a big whopping cap after the regulation stage.
Your post on how far you can take a regulator reminds me of another downside to modelling/simulation software, the fact that you can test whatever you want without spending a single cent. I started a little design project a few months ago to create a high current regulation circuit for a power amp. The development path you describe is exactly what I did in spice, started with a voltage follower, changed it to a differential, started adding CCS's, then darlingtoned the pass transistors, then realized that it would work fine as long it never had to turn on, etc. In the end, I had wasted literally weeks of time refining a regulator design that became more costly and complex than the amp it was to power. One day I finally recognized my lunacy and realized that it was far too expensive and complex to justify in reality, and scrapped it. If I would have had to build and test the thing, it never would have got that far out of hand.
Cheers, Terry
EDIT: Oh yeah, I was going to mention that I 100% agree with you on the big wad of capacitance after the regulators. In the development of my Zen headphone amp the biggest improvement that resulted from a single parts change was when I added a big whopping cap after the regulation stage.
Precisely. I just go build the silly things instead of spinning in circles trying to argue all sides of the issue.
Now, I will confess a curious thing...while I adore simple audio circuits, I am not all that bothered by the idea of complicated power supplies. I frequently regulate each and every stage of a circuit separately. Doesn't bother me a bit to have all kinds of different voltages going on; after all, once you're using separate regulators, there's no reason not to set them to different voltages if it works out in the circuit. As a concrete example, the line stage I'm doing right now (the solid state one) uses +30 and -10V rails. The CCS under the differential didn't need to be dissipating any more heat than necessary, so I let the power supply drop the heat. They're more robust devices, anyway.
Grey
Now, I will confess a curious thing...while I adore simple audio circuits, I am not all that bothered by the idea of complicated power supplies. I frequently regulate each and every stage of a circuit separately. Doesn't bother me a bit to have all kinds of different voltages going on; after all, once you're using separate regulators, there's no reason not to set them to different voltages if it works out in the circuit. As a concrete example, the line stage I'm doing right now (the solid state one) uses +30 and -10V rails. The CCS under the differential didn't need to be dissipating any more heat than necessary, so I let the power supply drop the heat. They're more robust devices, anyway.
Grey
X vs Aleph complication
Evening All,
Until Christmas I was just about to order all my parts for 2 Aleph 30's, or a 30 and a 60, after I had consulted this venerable board for final advice on some fine points of power supply, and how to set up PSUD II to help me out.
But Christmas got in the way and I decided I needed to buy an ultralight(!), but wife, quite reasonably said "NO" and now I am back living in reality, or as near as I can so judge my current mental state to be.
I have read, but not necessarily understood, the first 400 posts of this thread thinking I might cast my attentions to the Aleph X rather than a straight Aleph. But, at around post 400, Kilowattski, quite a bright chappie it seems, was having lots of trouble setting up his Aleph X.
The impression I have picked up is that the parts selection and setting up of an Aleph X is much more difficult than for an Aleph, and that small errors and modifications are much more unpredictable or difficult to predict than the standard amp.
1. Is this correct?
I had planned to "supe" up the Aleph with some inductors in the power supply, low value bypass all the large capacitors and buy the "best" caps for the signal path I could find.
2. Bearing this in mind, has anyone compared the X with a "suped up" version of a standard Aleph? Is the "extra work" worth it? (I believe in asking purely quantitative, objective questions as you can see!)
I am concerned, because I don't want to have another unfinished project lying around if I start on something too complicated. (e.g. re-plumbing the waste pipe for the bedroom airconditioner, re-finishing the front verandah's wood grain protection, re-aligning the settling stumps under the front sliding doors which have moved over 5 or 6 wet seasons, filling in my tax returns, learning to carve a gybe on my windsurfer, and repairing the hole its nose, etc. etc.) ... although a lot of those look like work rather than "projects".
Regards,
George.
Evening All,
Until Christmas I was just about to order all my parts for 2 Aleph 30's, or a 30 and a 60, after I had consulted this venerable board for final advice on some fine points of power supply, and how to set up PSUD II to help me out.
But Christmas got in the way and I decided I needed to buy an ultralight(!), but wife, quite reasonably said "NO" and now I am back living in reality, or as near as I can so judge my current mental state to be.
I have read, but not necessarily understood, the first 400 posts of this thread thinking I might cast my attentions to the Aleph X rather than a straight Aleph. But, at around post 400, Kilowattski, quite a bright chappie it seems, was having lots of trouble setting up his Aleph X.
The impression I have picked up is that the parts selection and setting up of an Aleph X is much more difficult than for an Aleph, and that small errors and modifications are much more unpredictable or difficult to predict than the standard amp.
1. Is this correct?
I had planned to "supe" up the Aleph with some inductors in the power supply, low value bypass all the large capacitors and buy the "best" caps for the signal path I could find.
2. Bearing this in mind, has anyone compared the X with a "suped up" version of a standard Aleph? Is the "extra work" worth it? (I believe in asking purely quantitative, objective questions as you can see!)
I am concerned, because I don't want to have another unfinished project lying around if I start on something too complicated. (e.g. re-plumbing the waste pipe for the bedroom airconditioner, re-finishing the front verandah's wood grain protection, re-aligning the settling stumps under the front sliding doors which have moved over 5 or 6 wet seasons, filling in my tax returns, learning to carve a gybe on my windsurfer, and repairing the hole its nose, etc. etc.) ... although a lot of those look like work rather than "projects".
Regards,
George.
I'd build an amp that best suits your needs and skill level.
I wouldn't build an Aleph-X as my first amp. It is a little bit more
complicated than building an Aleph.
If this is your first amp, i'd build something from the ZEN series.
Construction articles are a big help! You are more likely to have
a finished, working amp if you do so.
Also, an Aleph (or ZEN) will sound wonderful without a bunch of fancy
expensive parts. Saves you money (a good thing), Allows for
"upgrades" later (when you get the bug to do some mods!)
Good luck!
I wouldn't build an Aleph-X as my first amp. It is a little bit more
complicated than building an Aleph.
If this is your first amp, i'd build something from the ZEN series.
Construction articles are a big help! You are more likely to have
a finished, working amp if you do so.
Also, an Aleph (or ZEN) will sound wonderful without a bunch of fancy
expensive parts. Saves you money (a good thing), Allows for
"upgrades" later (when you get the bug to do some mods!)
Good luck!
George,
building an X isn´t that much more complicated than an Aleph. For sound comparisons and a bit of information you can look at this thread:
http://www.diyaudio.com/forums/showthread.php?threadid=49528
William
building an X isn´t that much more complicated than an Aleph. For sound comparisons and a bit of information you can look at this thread:
http://www.diyaudio.com/forums/showthread.php?threadid=49528
William
How to archive big threads
Dear All
Just a quick question (3 questions):
1. I would like to sit and mull over the "Aleph X thread" and archive it. There are only 2700 posts after all.
When I hit the "Show Printable Version" and then "Show all 2689 posts on one page", the system seems to time-out or something about 1/3 through the process leaving me a blank page.
Is it possible to do this, or am I asking too much.
2. Also, is there a way when using "Show Printable Version" to get the thumbnails and/or images to show up.
3. Of course, if there is a way of archiving the whole lot in the "normal" view, e.g. by showing all posts rather than 10 per page, that would do also.
Regards and thanks,
George.
PS Didn't post on that thread, because it might just have started up again, and I have now downloaded the 50 pages at 50 posts per pages in html format! So now, this question is for future reference.
Dear All
Just a quick question (3 questions):
1. I would like to sit and mull over the "Aleph X thread" and archive it. There are only 2700 posts after all.
When I hit the "Show Printable Version" and then "Show all 2689 posts on one page", the system seems to time-out or something about 1/3 through the process leaving me a blank page.
Is it possible to do this, or am I asking too much.
2. Also, is there a way when using "Show Printable Version" to get the thumbnails and/or images to show up.
3. Of course, if there is a way of archiving the whole lot in the "normal" view, e.g. by showing all posts rather than 10 per page, that would do also.
Regards and thanks,
George.
PS Didn't post on that thread, because it might just have started up again, and I have now downloaded the 50 pages at 50 posts per pages in html format! So now, this question is for future reference.
40 Watt Aleph-X
I am starting to build the standard 40 watt version of the Aleph-X and am looking for a CRC power supply schematic. I believe I will need (for stereo) a 500VA transformer with +12v, -12v independant secondaries, about ten (10) 10,000uf electrolitic capacitors, a CL-60 thyrister to reduce power surge at turn-on, and four 6A fast recovery rectifying diodes. The case is under construction. The heat sinks are large enough for a 100 watt version if I decide I need more power later. I am going to use this amp to power the midrange speakers in a four way active crossover system. Comments and suggestions on the power supply and for building the standard 40 watt Aleph-X amp are much appreciated. Thanks
Larry C
I am starting to build the standard 40 watt version of the Aleph-X and am looking for a CRC power supply schematic. I believe I will need (for stereo) a 500VA transformer with +12v, -12v independant secondaries, about ten (10) 10,000uf electrolitic capacitors, a CL-60 thyrister to reduce power surge at turn-on, and four 6A fast recovery rectifying diodes. The case is under construction. The heat sinks are large enough for a 100 watt version if I decide I need more power later. I am going to use this amp to power the midrange speakers in a four way active crossover system. Comments and suggestions on the power supply and for building the standard 40 watt Aleph-X amp are much appreciated. Thanks
Larry C
Hello,
Some of you may have seen me be a real pain in the but trying to get my Aleph 30 up and running, thank you to all who helped; I learned a lot. I got it up 'ok' right some time after I received Kari's boards. The boards are so nice it made me realize all I had done was make a me a mess that made music. I'm not satisfied with myself, ime for a better project. Not to mention my toroids have a little buzz.
The transformer I plan on using is here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=41075&highlight=
The thing is really quite large and can deliver WAY more than any amp would need (almost any).
I am proposing a separate 'universal' power supply to run my Pass amps now and in the future. How about a chassis containing this transformer. Have maybe six power outputs (+ 0 - on each output..each output will run an amp). Each output having its own bridge and capacitor bank. Room would be left for a Resistor or Inductor on each rail right before it exits. The monoblocs will be tied with an imbilical cord of maybe 12/3 or 10/3 SJ type cable(maybe smaller if the cable were to be some of the resistor in a crc!). Within the monobloc there will also be local capacitance similar to what is provided in the power supply.
Reasoning:
I am effectively creating a crc or clc (long range). I can modify voltage to a certain extent on a pair of pw/sup outputs to suit a particular amp. I would expect output to be ~ +-27v prior to any resistor or choke using my 20v secondaries.
I have some nice heat sinks to make some cute 3 or 4 sided mini aleph 3 type chassis' at about 8" x 8" x 7" high all sink.
Perhaps an AX for the midbasses and a A30/Mini A (briangt) for the tweets....and room for a couple more later.
Am I losing my mind here?
Some of you may have seen me be a real pain in the but trying to get my Aleph 30 up and running, thank you to all who helped; I learned a lot. I got it up 'ok' right some time after I received Kari's boards. The boards are so nice it made me realize all I had done was make a me a mess that made music. I'm not satisfied with myself, ime for a better project. Not to mention my toroids have a little buzz.
The transformer I plan on using is here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=41075&highlight=
The thing is really quite large and can deliver WAY more than any amp would need (almost any).
I am proposing a separate 'universal' power supply to run my Pass amps now and in the future. How about a chassis containing this transformer. Have maybe six power outputs (+ 0 - on each output..each output will run an amp). Each output having its own bridge and capacitor bank. Room would be left for a Resistor or Inductor on each rail right before it exits. The monoblocs will be tied with an imbilical cord of maybe 12/3 or 10/3 SJ type cable(maybe smaller if the cable were to be some of the resistor in a crc!). Within the monobloc there will also be local capacitance similar to what is provided in the power supply.
Reasoning:
I am effectively creating a crc or clc (long range). I can modify voltage to a certain extent on a pair of pw/sup outputs to suit a particular amp. I would expect output to be ~ +-27v prior to any resistor or choke using my 20v secondaries.
I have some nice heat sinks to make some cute 3 or 4 sided mini aleph 3 type chassis' at about 8" x 8" x 7" high all sink.
Perhaps an AX for the midbasses and a A30/Mini A (briangt) for the tweets....and room for a couple more later.
Am I losing my mind here?
Banned
Joined 2002
I have noted in some previous posts that in my case the absolute DC offset is very difficult to adjust.It starts off around 3v and needs around 1 and half hours before it stabilizes very slowly to +- 200mv.If I open the top of the case to adjust then the temp change immediately affects the offset so I am chasing it around.In fact just leaving the top panel open is enough to affect offset by a couple of volts.I guess that maybe my difference is that I doubled the bias on the diff pair so maube that is why it is so sensitive.That is all I did- the rest is standard.But still I cannot believe thatl just a couple of degrees of temperature can affect the operation of a circuit that much.It is like hyper sensitive thermometer.
The good thing is that relative offset is always not more than 50mv.
However I always worry that the amp might drift too much because of various factors such as mains voltage , room temperature etc. and sometimes this has been the case.
I think the effect is mainly because of the diff pair ccs mosfet destabilising with very small temp changes.
What are your experiences and what is the solution?
The good thing is that relative offset is always not more than 50mv.
However I always worry that the amp might drift too much because of various factors such as mains voltage , room temperature etc. and sometimes this has been the case.
I think the effect is mainly because of the diff pair ccs mosfet destabilising with very small temp changes.
What are your experiences and what is the solution?
Protos,
I believe Grey recommended the two mosfets be mounted back to back (and insolated with mica pads) to a large piece of aluminum, not a heat sink per se, but just something to give the pair some thermal stability.
The Rest of you out there,
Still haven't heard from anyone who has built the stock X and what they may want to share with the rest of us. Doesn't look like there are many working Aleph X's out there as yet. Maybe a dozen or so?
Well anyway, I am forging ahead. I decided to go with a dual power supply and have purchased two Hammond 300VA, 12 volt torroids. As of now, I have built the two power supplies as C only, each with ten 4,900uf caps. I may add chokes later if the ripple is too high. I have read Nelson's tutorial on mosfet matching which is my next task. I purchased twenty IRFP044 and twenty IRFP9610, mosfets. Each type is from the same manufacturing lot. I have a question on this. Do I just match the gate turn on voltage or should I match the transconductance as well? Which way these mosfets used - common source, common drain or common gate?
Larry
I believe Grey recommended the two mosfets be mounted back to back (and insolated with mica pads) to a large piece of aluminum, not a heat sink per se, but just something to give the pair some thermal stability.
The Rest of you out there,
Still haven't heard from anyone who has built the stock X and what they may want to share with the rest of us. Doesn't look like there are many working Aleph X's out there as yet. Maybe a dozen or so?
Well anyway, I am forging ahead. I decided to go with a dual power supply and have purchased two Hammond 300VA, 12 volt torroids. As of now, I have built the two power supplies as C only, each with ten 4,900uf caps. I may add chokes later if the ripple is too high. I have read Nelson's tutorial on mosfet matching which is my next task. I purchased twenty IRFP044 and twenty IRFP9610, mosfets. Each type is from the same manufacturing lot. I have a question on this. Do I just match the gate turn on voltage or should I match the transconductance as well? Which way these mosfets used - common source, common drain or common gate?
Larry