rtirion
Good to see you online, how are you my friend? My information is from the XA160 and XA200 product manuals available on the pass website. The manuals clearly state that he is using RC filtering for those amps. I've never seen the insides of either so if there is a disparity I can't explain it.
Good to see you online, how are you my friend? My information is from the XA160 and XA200 product manuals available on the pass website. The manuals clearly state that he is using RC filtering for those amps. I've never seen the insides of either so if there is a disparity I can't explain it.
Rclc
To add to the confusion:🙂
I clearly remember a post from NP that he uses a RCLC config,
in the XA's
Maybe different revisions? Is it really important?
Very good results are achieveable with all different configs.
I just searched and found:
http://www.diyaudio.com/forums/showthread.php?threadid=22657&highlight=
I also remember the usage of NTC's in a prototype/early model,
but there were some issues.
Regards
To add to the confusion:🙂
I clearly remember a post from NP that he uses a RCLC config,
in the XA's
Maybe different revisions? Is it really important?
Very good results are achieveable with all different configs.
I just searched and found:
http://www.diyaudio.com/forums/showthread.php?threadid=22657&highlight=
I also remember the usage of NTC's in a prototype/early model,
but there were some issues.
Regards
rtirion
The manual indicates "RC filtering" and that could mean resistance before the pi filter or the 'pi portion' following the capacitance of a CRC configuration. He doesn't state the presence of thermistor(s) or their placement. Thermistors might even be placed before rectification to deal with the inrush and soften the blow to the diodes. With 6-25mF caps, the option is there to use three pairs instead of the traditional two banks of three so the configuration of the actual supply could have many permutations not indicated in the manual. Nelson Pass has posted in this thread and perhaps with some encouragement he will clear up the confusion and tell us more about the power supply in the larger XAs.
The manual indicates "RC filtering" and that could mean resistance before the pi filter or the 'pi portion' following the capacitance of a CRC configuration. He doesn't state the presence of thermistor(s) or their placement. Thermistors might even be placed before rectification to deal with the inrush and soften the blow to the diodes. With 6-25mF caps, the option is there to use three pairs instead of the traditional two banks of three so the configuration of the actual supply could have many permutations not indicated in the manual. Nelson Pass has posted in this thread and perhaps with some encouragement he will clear up the confusion and tell us more about the power supply in the larger XAs.
Hang on, hang on...
Note that the circuits use different topologies. Don't underestimate the effect of a circuit's overall CMRR. For instance, a differential is more resistant to a less than perfect rail voltage than a single-ended stage.
I've never bothered to measure the relative CMRRs of an X vs. an Aleph, but I wouldn't be surprised if the topologies differed somewhat in that respect.
Under ideal circumstances, I'd use inductors rather than resistors. However, there are times when you want to burn off a few volts to get the rail down to a pre-determined target range. Obviously, resistors are a great choice, here. If, on the other hand, you're trying to get a rail as smooth and quiet as possible with as little voltage drop as possible, then inductors are a must. Okay, so where does that leave you? It means that you have to take power supply design on a case by case basis.
Of course, you could regulate the rails. Unless you find yourself needing large heatsinks for the regulator, it's more compact and much higher performance in the sense that your rail (hence operating points) won't drift with unstable line voltages. Given the cost of large inductors, it might even turn out to be cheaper, though more expensive than resistors.
Grey
Note that the circuits use different topologies. Don't underestimate the effect of a circuit's overall CMRR. For instance, a differential is more resistant to a less than perfect rail voltage than a single-ended stage.
I've never bothered to measure the relative CMRRs of an X vs. an Aleph, but I wouldn't be surprised if the topologies differed somewhat in that respect.
Under ideal circumstances, I'd use inductors rather than resistors. However, there are times when you want to burn off a few volts to get the rail down to a pre-determined target range. Obviously, resistors are a great choice, here. If, on the other hand, you're trying to get a rail as smooth and quiet as possible with as little voltage drop as possible, then inductors are a must. Okay, so where does that leave you? It means that you have to take power supply design on a case by case basis.
Of course, you could regulate the rails. Unless you find yourself needing large heatsinks for the regulator, it's more compact and much higher performance in the sense that your rail (hence operating points) won't drift with unstable line voltages. Given the cost of large inductors, it might even turn out to be cheaper, though more expensive than resistors.
Grey
GRollins
Thanks for your input. As the man responsable for reinvigorating the Aleph and giving Nelson a new and successful product line based on your idea, I would suspect that you are privy to the information we seek and can clear up all our confusion once and for all. Does Nelson Pass use inductors in the larger AXs and if so, why does the manual describe it as 'an unregulated supply with RC filtering'?
Thanks for your input. As the man responsable for reinvigorating the Aleph and giving Nelson a new and successful product line based on your idea, I would suspect that you are privy to the information we seek and can clear up all our confusion once and for all. Does Nelson Pass use inductors in the larger AXs and if so, why does the manual describe it as 'an unregulated supply with RC filtering'?
First things first...although I posted the concept that later became the Aleph-X quite some time before I started the Aleph-X thread--and wouldn't be surprised if Nelson read the post--I don't claim to have given him the idea. He's quite capable of coming up with his own ideas. No one would be more surprised than I if it turned out that I put the idea into his head. To me it seemed quite obvious to mix and match the Aleph and X topologies, since one was centered on the front end and the other on the output stage. Nelson was kind enough to allow me to fiddle with the things without sending a herd of lawyers after me.
Yes, some of his other ideas can be matched together. Whether I do a post on one of the other permutations depends on many things.
As far as the power supply question goes, I believe Nelson started the XA production run with CRCRC filtering, using MOVs as the R. Clever. Reduced the inrush on turn-on and then got out of the way. However, in the real world, the parts weren't matching well and there was current hogging which led to unequal heating of some of the MOVs. As far as I know, current product uses inductors in a humbucking configuration.
The manual was no doubt written at the time of initial release of the XA. It could simply be that Nelson & Co. haven't had the time to revise the text of the manual to reflect the production line changes. Face it, 99 out of 100 Pass customers will not read the technical stuff in the manual (indeed, probably don't read the manual at all), and would not care whether he uses CRC, CLC, or pixie dust constrained in a toroidal magnetic field. It's easy to get the feeling that everybody in the world is as obsessed with the inner working of things as we are, but it ain't so. Most people are content if the power indicator comes on and music comes out.
Grey
Yes, some of his other ideas can be matched together. Whether I do a post on one of the other permutations depends on many things.
As far as the power supply question goes, I believe Nelson started the XA production run with CRCRC filtering, using MOVs as the R. Clever. Reduced the inrush on turn-on and then got out of the way. However, in the real world, the parts weren't matching well and there was current hogging which led to unequal heating of some of the MOVs. As far as I know, current product uses inductors in a humbucking configuration.
The manual was no doubt written at the time of initial release of the XA. It could simply be that Nelson & Co. haven't had the time to revise the text of the manual to reflect the production line changes. Face it, 99 out of 100 Pass customers will not read the technical stuff in the manual (indeed, probably don't read the manual at all), and would not care whether he uses CRC, CLC, or pixie dust constrained in a toroidal magnetic field. It's easy to get the feeling that everybody in the world is as obsessed with the inner working of things as we are, but it ain't so. Most people are content if the power indicator comes on and music comes out.
Grey
GRollins
Nelson Pass has admitted struggling with his version of a common noise rejection scheme on this forum so I wouldn't be surprised if what was obvious to you wouldn't have occurred to him until you stated it so plainly. He was probably too wrapped up in the details of the AB version of the X amps to make the quantum leap of incorporating his retired line of Alephs as you did. The instant interest and popularity of the Aleph X thread was also a pretty good test market for Mr. Pass and probably encouraged him to launch the XA line so please don't be overly modest. Nelson Pass is one of the world's greatest audio designers but he's only human, isn't he? As I have stated before on this forum, there are detail people and aggregatists and many times what is easy for one is very difficult conceptually for the other. This is not a criticisim of either but a recognition that both create wealth. It has been stated elsewhere but I'll say it again for all the newbies who don't recognize your handle, kudos on a great idea.
Nelson Pass has admitted struggling with his version of a common noise rejection scheme on this forum so I wouldn't be surprised if what was obvious to you wouldn't have occurred to him until you stated it so plainly. He was probably too wrapped up in the details of the AB version of the X amps to make the quantum leap of incorporating his retired line of Alephs as you did. The instant interest and popularity of the Aleph X thread was also a pretty good test market for Mr. Pass and probably encouraged him to launch the XA line so please don't be overly modest. Nelson Pass is one of the world's greatest audio designers but he's only human, isn't he? As I have stated before on this forum, there are detail people and aggregatists and many times what is easy for one is very difficult conceptually for the other. This is not a criticisim of either but a recognition that both create wealth. It has been stated elsewhere but I'll say it again for all the newbies who don't recognize your handle, kudos on a great idea.
I treat the world as a series of building blocks, both large and small. Given a nut and a bolt, the potential is obvious. Given a nut and a piece of string, it's not necessarily as clear at the outset what you can do with the two, but a moment's reflection will tell you that the pair would make a dandy plumb line.
From what I can tell, Nelson looks at the world from a viewpoint not too different from my own. It would naturally occur to him to try the nut with a bolt, a piece of string, and possibly even with a coil of wire. Regardless of the timing, the Aleph output stage and the "X" (aka SuSy) topology were his ideas, and the credit belongs to him.
I'm just a little kid playing on the edge of a vast ocean. I build sand castles. The tide carries them away and wipes the slate clean for my next day's play. It's his sand. I play. It's entertaining for me and once in a while I learn something new. Every so often Nelson tosses another bucket of sand onto the beach.
In the meantime, the seagulls skree and dive for morsels and care not a whit.
I try to keep all this in perspective. It's just something I do with my spare time. It eats up pocket money, but I'm at home instead of out chasing female companionship. This pleases my wife and hopefully my two year-old daughter, whose knowledge of electronics consists of the single word,"music!"
It also helps heat the house during the winter.
Grey
From what I can tell, Nelson looks at the world from a viewpoint not too different from my own. It would naturally occur to him to try the nut with a bolt, a piece of string, and possibly even with a coil of wire. Regardless of the timing, the Aleph output stage and the "X" (aka SuSy) topology were his ideas, and the credit belongs to him.
I'm just a little kid playing on the edge of a vast ocean. I build sand castles. The tide carries them away and wipes the slate clean for my next day's play. It's his sand. I play. It's entertaining for me and once in a while I learn something new. Every so often Nelson tosses another bucket of sand onto the beach.
In the meantime, the seagulls skree and dive for morsels and care not a whit.
I try to keep all this in perspective. It's just something I do with my spare time. It eats up pocket money, but I'm at home instead of out chasing female companionship. This pleases my wife and hopefully my two year-old daughter, whose knowledge of electronics consists of the single word,"music!"
It also helps heat the house during the winter.
Grey
yldouright said:
Nice speculation, but not the case. The XA's existed for years
before Grey's post.
😎
Later....
My apologies if that seemed like a curt reply. Grey deserves
considerable credit for his benefit to this audience, if not to
my own endeavors.
😎
My apologies if that seemed like a curt reply. Grey deserves
considerable credit for his benefit to this audience, if not to
my own endeavors.
😎
Oaky, okay, you guys are all awesome, there is no doubt. I marvel at the magnitude knowledge you have.
But here is my situation:
I contain the knowledge of an ant and would really like your help. My last post was concerning my lack of output power in my toroid. Now, I could blaim Kristjen for telling me to get a 1200VA trannie, but I'm not going to do that....I could have read the manual for teh 20th time instead of just 19 times and realized the retail version took a 2KVA trannie instead of the 1.5KVA I bought. How much of a concern is this for me? This is 7.5 times thea rated output instead of 10 times....I suspect this insn't a big deal am I right? I'm putting an incredible amount of time and effort into making this project the absolute best it can be. I refuse to do anything half-a$$.
Secondly, Due to the unpredicability of the inductor in the power supply, (that is the problem with the LC correct?) would it be reasonable to have an LCRC, where the inductor handles 80% of the voltage drop for the rails and the last 20% can be fine tuned my the resistor? Right now I have a PSU that's running 68.45 volts to the rails with a 500 watt halogen shop light providing the load.
Thanks again you guys, I really appreciate all your time and unlimited patience with a novice as myself.
Chris
PS. Nelson, check out Sterling Vineyards 2001 Cabernet Sauvignon. Let it breath for about an hour, served at room temperature.
But here is my situation:
I contain the knowledge of an ant and would really like your help. My last post was concerning my lack of output power in my toroid. Now, I could blaim Kristjen for telling me to get a 1200VA trannie, but I'm not going to do that....I could have read the manual for teh 20th time instead of just 19 times and realized the retail version took a 2KVA trannie instead of the 1.5KVA I bought. How much of a concern is this for me? This is 7.5 times thea rated output instead of 10 times....I suspect this insn't a big deal am I right? I'm putting an incredible amount of time and effort into making this project the absolute best it can be. I refuse to do anything half-a$$.
Secondly, Due to the unpredicability of the inductor in the power supply, (that is the problem with the LC correct?) would it be reasonable to have an LCRC, where the inductor handles 80% of the voltage drop for the rails and the last 20% can be fine tuned my the resistor? Right now I have a PSU that's running 68.45 volts to the rails with a 500 watt halogen shop light providing the load.
Thanks again you guys, I really appreciate all your time and unlimited patience with a novice as myself.
Chris
PS. Nelson, check out Sterling Vineyards 2001 Cabernet Sauvignon. Let it breath for about an hour, served at room temperature.
GRollins said:
Grey-
After 15 yrs and spending more money than the best Bass boat costs and approaching a vacation home, I'm still playing with audio without a complaint from my wife.
On Friday night’s friends come over(or I go) and we mix/match components while relaxing with ____(insert beverage of choice).
My wife has tolerated and even encouraged it because at any time she knew where her husband was, and new how to reach him if she needed.
Occasionally she makes me bench press a few amplifiers to stay in shape but otherwise does not mind this hobby.
I'm glad I'm not the only one who stays OUT of trouble because of audio!!
If it's a question of maximal efficiency--meaning you don't want to lose any more current coming out of the transformer than necessary--definitely go with inductors.
The thing about transformers is that they heat up. So what do you do with heat? Get rid of it. Ventillate well, and consider using a fan on the transformer. Note also that all transformers are not the same. For instance, I've got some surplus 2kVA transformers that are approximately the same heft as 1kVA Plitrons that I use on the Aleph 2s. Build the circuit and run it. If the transformer is beefy enough, you may not have a problem at all. Add to that the fact that transformers are pretty hardy devices and you might be surprised.
jam,
Once upon a time you had manners and decency. It's a shame to see Fred's personality shining through you so transparently. I see that he still lacks a dictionary and the will to use it.
Grey
The thing about transformers is that they heat up. So what do you do with heat? Get rid of it. Ventillate well, and consider using a fan on the transformer. Note also that all transformers are not the same. For instance, I've got some surplus 2kVA transformers that are approximately the same heft as 1kVA Plitrons that I use on the Aleph 2s. Build the circuit and run it. If the transformer is beefy enough, you may not have a problem at all. Add to that the fact that transformers are pretty hardy devices and you might be surprised.
jam,
Once upon a time you had manners and decency. It's a shame to see Fred's personality shining through you so transparently. I see that he still lacks a dictionary and the will to use it.
Grey
Clarkcr said:
1) Don't worry about the tranny. It's all based on the mfr's
temperature anyway, and a good one assumes an 85 deg C
environment. I run transformers at more than 1/2 their rating
all the time - I just don't sell them to consumers that way, mostly
because they get mechanically noisy.
2) I know that Cab well, and it's very nice.
3) I don't know what the hell Jam is talking about, but I think
I'll stay that way.
😎
Clarkcr said:
How much current is each of these PSU's going to supply ?
If it is high, you will need only small values of R to drop a few volts to do your fine tuning of V. So why not use a longish length of copper wire to give this resistance and wind it into a coil...🙂
This way you will get an even quieter supply
mike
I would not say that for a given circuit that LC was unpredictable. It's just hard to predict it's predictable behaviour. spice is nice !
If the amp dissipates 500 watts at idle, and the rail is 60+ and 60-, and if the formula for wattage is E X I then, solving for "I" gives me a current of 8.333333 right?
I have SPICE installed but have not been able to run thus far. It won't run because I haven't been able to figure out how to change the polatity of the rail output or change any of the values. I must be retarded.
c
I have SPICE installed but have not been able to run thus far. It won't run because I haven't been able to figure out how to change the polatity of the rail output or change any of the values. I must be retarded.
c
This seems to be turning into rocket science.....no need for that.
I have made unregulated PSU's with 2mH air core inductors with pretty much anything from average to extreme capacities. CLC with 22,000uF - 2mH - 22,000uF to 100,000uF - 2mH - 100,000uF works well with no bad tendencies.
2mH have been chosen in order to keep the DCR and size down to a reasonable level, actually I have only made one psu with bigger inductors (4mH), which was no improvement. The 2mH figure seems to be what Nelson Pass have ended up using as standard for the Zen projects as well.
I guess that if you use iron core inductors you could get the resistance of the inductor low enough to get in trouble, but surely not with air core. I use 1.9mm wire for my inductors, which leaves you with something like 0.25-0.30 ohm.
Magura 🙂
I have made unregulated PSU's with 2mH air core inductors with pretty much anything from average to extreme capacities. CLC with 22,000uF - 2mH - 22,000uF to 100,000uF - 2mH - 100,000uF works well with no bad tendencies.
2mH have been chosen in order to keep the DCR and size down to a reasonable level, actually I have only made one psu with bigger inductors (4mH), which was no improvement. The 2mH figure seems to be what Nelson Pass have ended up using as standard for the Zen projects as well.
I guess that if you use iron core inductors you could get the resistance of the inductor low enough to get in trouble, but surely not with air core. I use 1.9mm wire for my inductors, which leaves you with something like 0.25-0.30 ohm.
Magura 🙂
Magura said:
Well, LC... is a bit more involved than CLC. The 1st inductor has to be big enough - for a given current to be drawn - to make sure that the current flowing in the transformer is always on.
This has the advantage the switching transients and FR ringing is not reflected back into the mains supply ( which can mess up the sound of all of your other audio equipment )
Chris - I sympathise on the spice front when I first ran my b2 spice I was totally baffled for a few days. After that things began to fall into place. It was well worth the effort, even though it can't tell you how the amp will sound, it's a great tool for learning what's going on and what changes have what effect etc
good luck
mike
mikelm said:
I am aware of the issues regarding LC filters, but so far I have seen little evidence that a LC is better than a CLC, it's just more trouble. Have anybody actually made a test of a LC VS. a CLC?
I made a LC filter some time ago, but could not hear any difference (this was before I got a scope, so it may be measurable, that I can't tell anything about), and decided against LC filters, simply to avoid the trouble.
I agree the theory is correct, but I am still to see one of my PSU's pollute the mains to a degree where the regular mains pollution would not set the "pollution floor".
Besides that a LC filter would require a substantially bigger inductor, which would mean that it would be either very expensive or very high DCR.
Is there something I have gotten basicly wrong here??
Magura 🙂
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