I did post a full schematic on the previous page, including PCB layout in native formats. It should be extremely easy for anyone to take that and run with it + modify whichever way they see fit.
I have verified that the input stage works (with the previous layout) but not that the layout is good. I have sinc then enhanced the layout with a Vbe multiplier and that will be verified.
I have yet to verify that the complete deal works (but I am sure it will). I am terribly sorry this is taking me so long.
Petter
I have verified that the input stage works (with the previous layout) but not that the layout is good. I have sinc then enhanced the layout with a Vbe multiplier and that will be verified.
I have yet to verify that the complete deal works (but I am sure it will). I am terribly sorry this is taking me so long.
Petter
Petter,
no, -I- am sorry. I should have looked for the schematic better before asking.
As far as the classA vs. ClassAB argument is concerned I use to despise classA amps for the dissipated power. I changed my mind after building one. Besides the fact that I prefer the classA sound I found them much more easily 'predictable' than AB. Especially the Pass designs. Basically as long as the heatsinks is dimensioned properly everything else just falls into place.
no, -I- am sorry. I should have looked for the schematic better before asking.
As far as the classA vs. ClassAB argument is concerned I use to despise classA amps for the dissipated power. I changed my mind after building one. Besides the fact that I prefer the classA sound I found them much more easily 'predictable' than AB. Especially the Pass designs. Basically as long as the heatsinks is dimensioned properly everything else just falls into place.
Thanks Petter for the reply!
I`m planning my audio projects on the very long run always and I´m not yet in building an X-Amp. but just collecting information enough in order to decide wether a project is feasible for me.
I´m pretty sure I`ll try it (I want to design a PCB layout too) also I´m not able developing circuits like this from scratch by my own, certainly I can debug or modify an existing circuit (and be it by trial and error only ). So thanks very much for Your kind offer for assistance
- one day I might come back for it.
Of course I´m highly interested in any further progress regarding Your work on the X-Amp and wish You good luck with it!
I`m planning my audio projects on the very long run always and I´m not yet in building an X-Amp. but just collecting information enough in order to decide wether a project is feasible for me.
I´m pretty sure I`ll try it (I want to design a PCB layout too) also I´m not able developing circuits like this from scratch by my own, certainly I can debug or modify an existing circuit (and be it by trial and error only ). So thanks very much for Your kind offer for assistance
- one day I might come back for it. Of course I´m highly interested in any further progress regarding Your work on the X-Amp and wish You good luck with it!
When I built layout version 1 of the input stage, I had a lot of trouble figuring out (literally days of head-scratching) what was going on. On an earlier page, I have posted instructions for how to reduce the amount of headscratching in such situations. Basically it involves removing a few components and setting up the current sources PRECISELY before connecting everything. My servo approach a la Aleph P 1.7 (+ voltage reference to increase drop) should solve this too.
Petter
Petter
In the end it does support...
I came across the discussions in this thread about using Nelson Pass' designs.
Some consider this to be detrimental to the interests of PassLabs.
Personally, I can only say that I would probably never earn enough money to buy me an original Passlabs product.
Through the sharing of his idea's I can enjoy listening to a first-class Amp, whereas I would have to live with some harshsounding thousand dollar Amp if I would have to buy some production-model.
That said, I think that the way we DIY-builders are being allowed to listen to PassLabs designs does make for a tremendous publicity for PassLabs.
I myself would certainly have never met with those amplifiers and their wonderful sound if there were no Pass DIY community.
Maybe I would vaguely know the name...
Now that I am familiar with it, I have become an Admirer and Supporter of Passlabs.
I have recommended PassLabs amps to friends and aquaintences of mine who do have the money to buy those products.
In at least two cases those persons have chosen a PassLabs where they initiately were planning to buy another brand.
I don't know whether other DIY-ers have had this experience, but in my case Nelson Pass in the end is clearly better off this way than when he would have chosen to stop sharing his ideas with us...
I think that only the lesser gifted people rely fully on staying in the dark, since they have no real merits to offer, apart from their usual humbug ideas...
Nevertheless, I agree that asking permission in such cases as these is always an absolute necessity, and shows the respect that we must have for such gifted people.
Let's hope there will always be talented, honoust folks like Mr. Pass in the audioworld!
Lucas.
I came across the discussions in this thread about using Nelson Pass' designs.
Some consider this to be detrimental to the interests of PassLabs.
Personally, I can only say that I would probably never earn enough money to buy me an original Passlabs product.
Through the sharing of his idea's I can enjoy listening to a first-class Amp, whereas I would have to live with some harshsounding thousand dollar Amp if I would have to buy some production-model.
That said, I think that the way we DIY-builders are being allowed to listen to PassLabs designs does make for a tremendous publicity for PassLabs.
I myself would certainly have never met with those amplifiers and their wonderful sound if there were no Pass DIY community.
Maybe I would vaguely know the name...
Now that I am familiar with it, I have become an Admirer and Supporter of Passlabs.
I have recommended PassLabs amps to friends and aquaintences of mine who do have the money to buy those products.
In at least two cases those persons have chosen a PassLabs where they initiately were planning to buy another brand.
I don't know whether other DIY-ers have had this experience, but in my case Nelson Pass in the end is clearly better off this way than when he would have chosen to stop sharing his ideas with us...
I think that only the lesser gifted people rely fully on staying in the dark, since they have no real merits to offer, apart from their usual humbug ideas...
Nevertheless, I agree that asking permission in such cases as these is always an absolute necessity, and shows the respect that we must have for such gifted people.
Let's hope there will always be talented, honoust folks like Mr. Pass in the audioworld!
Lucas.
Agreed
If you think about it, designs will get ripped off sooner or later anyway. Mr Pass is certainly not unfamiliar with this fact
Now, the community marketing done by Pass is extremely smart -- it serves all sides, and it is just about the only way a manufacturer can leverage anything positive out of the fact that people copy one another. It would be useful if other designers would think along those lines. Bruce Rosenblitz over at www.transcendentsound.com is using a similar approach.
One rather somber thought about the industry is that there is not really a lot of new ground being made. Perhaps this is the reason people keep their cards close to their chests?
Petter
If you think about it, designs will get ripped off sooner or later anyway. Mr Pass is certainly not unfamiliar with this fact
Now, the community marketing done by Pass is extremely smart -- it serves all sides, and it is just about the only way a manufacturer can leverage anything positive out of the fact that people copy one another. It would be useful if other designers would think along those lines. Bruce Rosenblitz over at www.transcendentsound.com is using a similar approach.
One rather somber thought about the industry is that there is not really a lot of new ground being made. Perhaps this is the reason people keep their cards close to their chests?
Petter
Petter,
I can't read the circuitmaker file I'd have to dowload the program that would take me forever... what I have seen is the whole schematic on gif. So do you have a new input stage now? Could you make a gif out of it?
I would surely be interested in building the amp since I already have the transformers and the chassis for it already. I think the chassis I have could dissipate 100watts/chn so the output stage will need to be scaled to whatever it needs to be.
Have you asked Nelson about servos? Does he use any? I am sure he must have some tricks up his sleeve to get the circuit to behave without using complicated circuitry, which would spoil the whole fun of having only two gain stages.
Lucas_G
every once in a while this comes up; the topic of intellectual and commercal property with specific regard to Nelson Pass's has been discussed 'at nauseaum' in this and many other threads. We are in the process of printing 800 Aleph X boards and he is perfectly OK with it. As long as one behaves with respect in a sportsman fashion, with no intent to profit everything is out in the open and the problem quite simply does not exist.
This site acually provides a safeguard for these kind of abuses of ever taking place. Pretty much who is who in audio today either looks at this site or is starting to look at this site or will become aware of this site very soon. So everyone's knows what's going on.
I can't read the circuitmaker file I'd have to dowload the program that would take me forever... what I have seen is the whole schematic on gif. So do you have a new input stage now? Could you make a gif out of it?
I would surely be interested in building the amp since I already have the transformers and the chassis for it already. I think the chassis I have could dissipate 100watts/chn so the output stage will need to be scaled to whatever it needs to be.
Have you asked Nelson about servos? Does he use any? I am sure he must have some tricks up his sleeve to get the circuit to behave without using complicated circuitry, which would spoil the whole fun of having only two gain stages.
Lucas_G
every once in a while this comes up; the topic of intellectual and commercal property with specific regard to Nelson Pass's has been discussed 'at nauseaum' in this and many other threads. We are in the process of printing 800 Aleph X boards and he is perfectly OK with it. As long as one behaves with respect in a sportsman fashion, with no intent to profit everything is out in the open and the problem quite simply does not exist.
This site acually provides a safeguard for these kind of abuses of ever taking place. Pretty much who is who in audio today either looks at this site or is starting to look at this site or will become aware of this site very soon. So everyone's knows what's going on.
-->I can't read the circuitmaker file
OK, so I am posting a GIF. I thought I had already done this, sorry. Note the voltage setup for bias of power stage (not shown, see postings page 1) are resistive and could be done with Vbe multiplier. It is some time since I looked at the circuit, so you need to verify the component values for whichever current you select. I set up for 30mA in each of the bottom current sources (and thus 60 for the two top ones).
-->Have you asked Nelson about servos? Does he use any? I am sure he must have some tricks up his sleeve to get the circuit to behave without using complicated circuitry, which would spoil the whole fun of having only two gain stages.
I have made macromodels for an op-amp version but have not put it toghether yet. The concept of macromodels (with PCB layout) is great! However, I ended up with revisiting the service manual for Aleph P 1.7 and saw the (same as Aleph) use of a simple bipolar device to sense the current and slave the FET source into compliance. After thinking about it some, I decided it was probably worthwile and better to do this, particularly if some voltage source is added to the Vbe drop which is far too low for my liking. I will make new macromodels etc. to accommodate. I have not asked NP about servos, but it is a natural evolution, particularly if done discreetly to avoid having to mess with biasing or worry about drift with temperature.
Petter
OK, so I am posting a GIF. I thought I had already done this, sorry. Note the voltage setup for bias of power stage (not shown, see postings page 1) are resistive and could be done with Vbe multiplier. It is some time since I looked at the circuit, so you need to verify the component values for whichever current you select. I set up for 30mA in each of the bottom current sources (and thus 60 for the two top ones).
-->Have you asked Nelson about servos? Does he use any? I am sure he must have some tricks up his sleeve to get the circuit to behave without using complicated circuitry, which would spoil the whole fun of having only two gain stages.
I have made macromodels for an op-amp version but have not put it toghether yet. The concept of macromodels (with PCB layout) is great! However, I ended up with revisiting the service manual for Aleph P 1.7 and saw the (same as Aleph) use of a simple bipolar device to sense the current and slave the FET source into compliance. After thinking about it some, I decided it was probably worthwile and better to do this, particularly if some voltage source is added to the Vbe drop which is far too low for my liking. I will make new macromodels etc. to accommodate. I have not asked NP about servos, but it is a natural evolution, particularly if done discreetly to avoid having to mess with biasing or worry about drift with temperature.
Petter
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I see you use MAT02 units at the bottom middle current sources. Those guys will se half the rail voltage (25V or so in this case) and might get hot. The sources of the input pair will always be in the region of zero volts, so it does not matter if you loose more voltage here and thus increase current source compliance while reducing power dissipation. Where you are dropping the most volts are at the top, and I am happy to see that you have compensated for this by adding 10V. If you were going more traditional, you would probably want to add 10V or more at the bottom as well for the outside bottom pair, but as I said, the top is the most critical.
Another trick you can use is to put the PSU caps across rails instead of to ground. You will need higher voltage caps, but you will get much more mileage out of them. As you see, ground is not used at all by the power stage, why reference to it!
It is a matter of taste whether you want to reference the feedback to the output or back up one step.
680R to ground should not be necessary. Also, you might want to consider playing with the 100R bridge between input pair sources since the final gain is limited upwards by the output/input resistors.
Nice work! Let us know how you get on with it.
Petter
I see you use MAT02 units at the bottom middle current sources. Those guys will se half the rail voltage (25V or so in this case) and might get hot. The sources of the input pair will always be in the region of zero volts, so it does not matter if you loose more voltage here and thus increase current source compliance while reducing power dissipation. Where you are dropping the most volts are at the top, and I am happy to see that you have compensated for this by adding 10V. If you were going more traditional, you would probably want to add 10V or more at the bottom as well for the outside bottom pair, but as I said, the top is the most critical.
Another trick you can use is to put the PSU caps across rails instead of to ground. You will need higher voltage caps, but you will get much more mileage out of them. As you see, ground is not used at all by the power stage, why reference to it!
It is a matter of taste whether you want to reference the feedback to the output or back up one step.
680R to ground should not be necessary. Also, you might want to consider playing with the 100R bridge between input pair sources since the final gain is limited upwards by the output/input resistors.
Nice work! Let us know how you get on with it.
Petter
makes me proud
NP´s statement makes me proud!!
BTW the MAT 02 sees about 10 Volts across C-E
About 4 V drop as the sources of the IRF620 are at -4v
another 10V across that 1k resistor (running at 10mA)
another volt across the 100R res.
I´m running it at 40% rated power, you can touch it without
burning your fingers.
You have to carefully select those led´s for about 1,65V at
their current.
Reason for the MAT AND 100R 0.1% (!) is the intrinsic
matching of the 2 devices in one housing.
The combination of 680R and 100R is simply doubled values
from NP´s patent . You can buy a copy from the patentserver
wich is mentioned on Nelsons hp.(3$ per download).
There you can read the reason for that 300R-47R network.
I think you simply need some DC-current path to reference
(ground)
Adjust as follows:
shortcut the gatestoppers of the N and P Powerfets and adjust output to zero with the trimmer in the currentsource in the +v rail.
secondly open the shortcut, let the Fets warm up (1h or so)
readjust DC-offset with trimmers in the gate circuit of outputstage.
You can also swap the ALEPH Current Sink and put in a complementary stage with P-Fets as source followers, but as
the IRFP9140(N) is not really complementary to IRFP240 I´m
not so sure about the behaviour under heavy complex load.
The simple circuit of our genius
indeed works fine either with P or N-MOSFETS
Uli
NP´s statement makes me proud!!
BTW the MAT 02 sees about 10 Volts across C-E
About 4 V drop as the sources of the IRF620 are at -4v
another 10V across that 1k resistor (running at 10mA)
another volt across the 100R res.
I´m running it at 40% rated power, you can touch it without
burning your fingers.
You have to carefully select those led´s for about 1,65V at
their current.
Reason for the MAT AND 100R 0.1% (!) is the intrinsic
matching of the 2 devices in one housing.
The combination of 680R and 100R is simply doubled values
from NP´s patent . You can buy a copy from the patentserver
wich is mentioned on Nelsons hp.(3$ per download).
There you can read the reason for that 300R-47R network.
I think you simply need some DC-current path to reference
(ground)
Adjust as follows:
shortcut the gatestoppers of the N and P Powerfets and adjust output to zero with the trimmer in the currentsource in the +v rail.
secondly open the shortcut, let the Fets warm up (1h or so)
readjust DC-offset with trimmers in the gate circuit of outputstage.
You can also swap the ALEPH Current Sink and put in a complementary stage with P-Fets as source followers, but as
the IRFP9140(N) is not really complementary to IRFP240 I´m
not so sure about the behaviour under heavy complex load.
The simple circuit of our genius
indeed works fine either with P or N-MOSFETS Uli
