Nordic,
It is an implementation of a Howland type current pump using a power op amp. There is nothing really new about the current pump idea.
Mauro used this concept along with the LM318 driver similar to the MF power amp.
I simply used the same concept, but my driver is fully symmetrical and this is beneficial to for the pump, as it allows for 6db more swing.
You can read about this circuit here:
http://www.national.com/an/AN/AN-29.pdf
And here:
http://www.inginerie.protectia-mediului.ro/engineering/electronics/circuits/converters/c4.html
Mauro talked about the "Stasis Bridge" use of this type circuit before "My Ref" was ever brought to us.
I have been experimenting with it since I saw it then.
Cheers!
Russ
It is an implementation of a Howland type current pump using a power op amp. There is nothing really new about the current pump idea.
Mauro used this concept along with the LM318 driver similar to the MF power amp.
I simply used the same concept, but my driver is fully symmetrical and this is beneficial to for the pump, as it allows for 6db more swing.
You can read about this circuit here:
http://www.national.com/an/AN/AN-29.pdf
And here:
http://www.inginerie.protectia-mediului.ro/engineering/electronics/circuits/converters/c4.html
Mauro talked about the "Stasis Bridge" use of this type circuit before "My Ref" was ever brought to us.
I have been experimenting with it since I saw it then.
Cheers!
Russ
Thanks... reading it now... the "input current" they are talking about is the the current of signal?
The reason this is so exciting is because of the fully symmetrical nature of my circuit (when used in X bridge mode) you get incredibly good PSRR and CMRR, better than any single ended solution could provide.
The bonus is you get that symmetry effect with SE input or balanced input into the driver. It is the circuit GFB itself that is symmetrical. Common mode noise from both pumps is effectively neutralized.
And the sound.... well I could say, but I will let someone else build it and say it for me.
There is nothing like it, well Aleph X is very similar.
Cheers!
Russ
The bonus is you get that symmetry effect with SE input or balanced input into the driver. It is the circuit GFB itself that is symmetrical. Common mode noise from both pumps is effectively neutralized.
And the sound.... well I could say, but I will let someone else build it and say it for me.
There is nothing like it, well Aleph X is very similar.Cheers!
Russ
Ok we are going to have to have cybersex in order for me to pay you for sending me a schematic for personal use of course... I have some chips that I'd love to try this on.
Just jokeing of course.. about the first part... some people can be so weird about jokes like that...
Just jokeing of course.. about the first part... some people can be so weird about jokes like that...
troystg said:
Yes I will open a new thread. I am collecting my thoughts to do it, but just wanted to introduce it here since Mauro was the one who pointed me to the use of the Howland style pump (it is used in all revisions of My_Ref).
Thanks Mauro!! 😀
As for kits, I am not sure if or when, I will have to talk it over with Brian. We have so many projects coming to a head.
Cheers!
Russ
Evolution amp transformer.
I earlier posted that Mauro said I could use anything up to a 500VA transformer.
I feel I should qualify this statement, so as not to convey the wrong impression.
A 500VA TX can of course be used, but Mauro thinks it is not the best choice. He tried it but prefers his Nuvotem 300VA TX.
His advice to me was to use a transformer no bigger than the 400VA TX that I was thinking of using.
Audie.
I earlier posted that Mauro said I could use anything up to a 500VA transformer.
I feel I should qualify this statement, so as not to convey the wrong impression.
A 500VA TX can of course be used, but Mauro thinks it is not the best choice. He tried it but prefers his Nuvotem 300VA TX.
His advice to me was to use a transformer no bigger than the 400VA TX that I was thinking of using.
Audie.
billabong said:
It almost never hurts to use a larger VA transformer, sometimes (rarely) though some components should be adjusted, such as the cap between the AC inputs on the PS section. The reason could be that the inductance of the of the secondaries changes.
I think Mauro was probably just pointing out that anything bigger than 400VA would be wasted or overkill, and he is right.
Cheers!
Russ
Thanks Russ,
That would be at least part of the reason. He mentioned there may be a problem with the magnetic field ( a 4.5kg 500VA Toroid fairly close to the PCB).
I understood that Mauro also prefers the sound when using the smaller 300VA TX (unless I lost something in the translation).
Cheers,
Audie.
That would be at least part of the reason. He mentioned there may be a problem with the magnetic field ( a 4.5kg 500VA Toroid fairly close to the PCB).
I understood that Mauro also prefers the sound when using the smaller 300VA TX (unless I lost something in the translation).
Cheers,
Audie.
A humble request
Could you please have a dummied down explanition on the new thread for those of us that are still learning? What is GFB, I know what PSRR, AND CMRR are, but the rest of the explanition (semmety effect) is over my head. but I do want to learn all I can,
I read the links you provided and printed them to study.
Thank You.
Russ White said:The reason this is so exciting is because of the fully symmetrical nature of my circuit (when used in X bridge mode) you get incredibly good PSRR and CMRR, better than any single ended solution could provide.
The bonus is you get that symmetry effect with SE input or balanced input into the driver. It is the circuit GFB itself that is symmetrical. Common mode noise from both pumps is effectively neutralized.
And the sound.... well I could say, but I will let someone else build it and say it for me.
Cheers!
Russ
Could you please have a dummied down explanition on the new thread for those of us that are still learning? What is GFB, I know what PSRR, AND CMRR are, but the rest of the explanition (semmety effect) is over my head. but I do want to learn all I can,
I read the links you provided and printed them to study.
Thank You.
Question about rail voltage.
Since there have been several prototypes build of the ss design, what has been the range of rail voltages used?
I know the rails needed for the input circuit, I remember seeing some of the other SS circuits using low voltage rails than the 33- 34 volt used in the My_Ref.
I have looked through my junk pile and will need transformers most likely.
George
Since there have been several prototypes build of the ss design, what has been the range of rail voltages used?
I know the rails needed for the input circuit, I remember seeing some of the other SS circuits using low voltage rails than the 33- 34 volt used in the My_Ref.
I have looked through my junk pile and will need transformers most likely.
George
Re: Question about rail voltage.
I am using 28V rails for the pump (and for TPM-3886) in bridged parallel mode. The driver is using 15V rails.
I use a dual 20V 500VA per channel.
Cheers!
Russ
Panelhead said:
I am using 28V rails for the pump (and for TPM-3886) in bridged parallel mode. The driver is using 15V rails.
I use a dual 20V 500VA per channel.
Cheers!
Russ
Re: A humble request
I will try to explain better later in the new thread, but GFB is "global feedback".
Here is some reading on Super Symmetry:
http://cygnus.ipal.org/mirror/www.passlabs.com/susy.htm
ppcblaster said:
I will try to explain better later in the new thread, but GFB is "global feedback".
Here is some reading on Super Symmetry:
http://cygnus.ipal.org/mirror/www.passlabs.com/susy.htm
An interesting evening at Audiopax http://www.audiopax.com/
yesterday.
Took My_Evolution to test up against Eduardos new class A monoblocks (10,000USD retail).
Preamp was Model 5 (5.000USD), speakers were Audiopax own reference (15.000USD) and source was a good Meridian player.
Main auditioning tracks were Vivaldi:Gloria , Kings College Choir,Cambridge,EMI
Carmen Mc Rae, Live at the dug,JVC
Steve Davis,Quality of silence,DMP
Rimsky-korsakov,Dance of the tumblers,Reference Recordings
All tracks were chosen by me and were well known very high quality recordings and performances.
My great thanks and appreciation to Eduardo for indulging a DIYer like me and finding the time from his very busy schedule to spend a couple of hours listening to music.
The audiopax system is the best I have heard even compared to some really hi-end stuff I have heard at various shows over the years.Of course it is well set-up and extremely synergistic because it was designed that way.
Although we did not get a chance to hear the valve monoblocks which are already well known in hi-end circles Eduardo told me that the new class a monos are in the same league and manage to sound like a very good tube amp which was confirmed by subsequent audition.
This is a picture from my files of the Audiopax system.
yesterday.
Took My_Evolution to test up against Eduardos new class A monoblocks (10,000USD retail).
Preamp was Model 5 (5.000USD), speakers were Audiopax own reference (15.000USD) and source was a good Meridian player.
Main auditioning tracks were Vivaldi:Gloria , Kings College Choir,Cambridge,EMI
Carmen Mc Rae, Live at the dug,JVC
Steve Davis,Quality of silence,DMP
Rimsky-korsakov,Dance of the tumblers,Reference Recordings
All tracks were chosen by me and were well known very high quality recordings and performances.
My great thanks and appreciation to Eduardo for indulging a DIYer like me and finding the time from his very busy schedule to spend a couple of hours listening to music.
The audiopax system is the best I have heard even compared to some really hi-end stuff I have heard at various shows over the years.Of course it is well set-up and extremely synergistic because it was designed that way.
Although we did not get a chance to hear the valve monoblocks which are already well known in hi-end circles Eduardo told me that the new class a monos are in the same league and manage to sound like a very good tube amp which was confirmed by subsequent audition.
This is a picture from my files of the Audiopax system.
Attachments
So this is part two.
How did the My_evolution fare against a production hi-end amp as described above?
I must say that I was a little bit nervous because the last time I had taken the my_ref amp which was not fully broken in and it had been beaten soundly by the audiopax amps.However, as I said it was before its transformation.The my_evolution is even better than the my_ref.
In a nutshell I would say the my_evolution and the class a monoblocks were in the same league.
Sure , they sounded different in that super detailed system and you could tell them apart .
The monblocks had a very nice warm midrange quality that was very tubelike.It drew your attention there.The my_evolution on the other hand seemed slightly faster and perhaps more extended on the extremes with more detail in the highs.Musically speaking ,in terms of flow , timbre,timing etc the two amps were equal.It was , I think more a matter of presentation than a different musicality.If I were a reviewer I would say the my_evolution put you a few rows closer towards the event/orchestra.
So all in all i would call it a tie even though others may prefer one or the other amp depending on ancillary equipment and tastes.
Eduardo was quite impressed with the amp and he repeated this very positive impression a few times.
So there you go.This might answer some that ask how does diy compare with the ´´big boys``.
edit: Oh and i must point out that the my_evolution does not really need a preamp,even a good one, _as it was auditioned_which means that it had the ability to sound even more transparent than the way it was tested.
How did the My_evolution fare against a production hi-end amp as described above?
I must say that I was a little bit nervous because the last time I had taken the my_ref amp which was not fully broken in and it had been beaten soundly by the audiopax amps.However, as I said it was before its transformation.The my_evolution is even better than the my_ref.
In a nutshell I would say the my_evolution and the class a monoblocks were in the same league.
Sure , they sounded different in that super detailed system and you could tell them apart .
The monblocks had a very nice warm midrange quality that was very tubelike.It drew your attention there.The my_evolution on the other hand seemed slightly faster and perhaps more extended on the extremes with more detail in the highs.Musically speaking ,in terms of flow , timbre,timing etc the two amps were equal.It was , I think more a matter of presentation than a different musicality.If I were a reviewer I would say the my_evolution put you a few rows closer towards the event/orchestra.
So all in all i would call it a tie even though others may prefer one or the other amp depending on ancillary equipment and tastes.
Eduardo was quite impressed with the amp and he repeated this very positive impression a few times.
So there you go.This might answer some that ask how does diy compare with the ´´big boys``.
edit: Oh and i must point out that the my_evolution does not really need a preamp,even a good one, _as it was auditioned_which means that it had the ability to sound even more transparent than the way it was tested.
Waiting on UPS
Got a case and 23 volt 400 va transformer coming to finally start on the Evolution. The circuit board has been sitting waiting on me.
I really like the mono My_Refs with a battery supply for the LM318's. If the Evolution improves on this it will be fine.
Is the Evolution easier to drive than the My_Ref? I liked the My_Ref better with an active line.
George
Got a case and 23 volt 400 va transformer coming to finally start on the Evolution. The circuit board has been sitting waiting on me.
I really like the mono My_Refs with a battery supply for the LM318's. If the Evolution improves on this it will be fine.
Is the Evolution easier to drive than the My_Ref? I liked the My_Ref better with an active line.
George
well, Mauro himself wrote to me that he prefers/uses a passive preamp on his amp and agrees that it not difficult to drive.
I cannot honestly say i noticed a difference between the two in terms of driving.
I just hate throwing out transparency when you dont need the gain or current of an an active pre.There is absolutely no way you will avoid this loss of transparency when you let your signal pass thru a handful of passive and active components.
Of course a lot will depend on your source and its output section.
I cannot honestly say i noticed a difference between the two in terms of driving.
I just hate throwing out transparency when you dont need the gain or current of an an active pre.There is absolutely no way you will avoid this loss of transparency when you let your signal pass thru a handful of passive and active components.
Of course a lot will depend on your source and its output section.
The input impedance is the same(100K) as far as I know, so you should not need a preamp.
I use a passive Joshua Tree attenuator on a pair of Rev Cs with very good reults.
Cheers!
Russ
I use a passive Joshua Tree attenuator on a pair of Rev Cs with very good reults.
Cheers!
Russ
Thanks protos for a very useful report on the Evolution Amp.
The description does sound similar to what could be said of the my_ref-c, except that the rev-c would lack mauro's refinements to the Evolution, which would result in improved sound.
The rev-c is very revealing of the signal feed, and the Evolution no doubt more so. Minute changes to my front end are immediately noticeable.
I'm looking forward to building the Evolution. I think Panelhead will beat me to it though.
Panelhead,
Any reason for getting 23V secondary TXs? Mauro specs 25V.
Audie.
The description does sound similar to what could be said of the my_ref-c, except that the rev-c would lack mauro's refinements to the Evolution, which would result in improved sound.
The rev-c is very revealing of the signal feed, and the Evolution no doubt more so. Minute changes to my front end are immediately noticeable.
I'm looking forward to building the Evolution. I think Panelhead will beat me to it though.
Panelhead,
Any reason for getting 23V secondary TXs? Mauro specs 25V.
Audie.
Just enough
I am also building another set of speakers, these are also 100 dB efficient, but 5 ohm instead of 15 ohm. In my mind, the lower rails are better with lower impedance loads.
Used the seven dollar PEX EI unit in all versions of My_Ref. This is a 48 volt ct unit. It ends up at 34 volts using the SIP rectifiers. Using lower loss restifiers and the +/- 23 volt toriods should give about the same rail voltage.
Also I am now using a passive volume control with the monos. That is why I asked about driving the Evolution.
The passive uses LDR's and is better sounding than all the pots and setted attenuators I have tried as a passive in the past.. For some reason the LDR is more dynamic and has more color than the others. It may just be the lack of moving contacts, that is what others have commented.
George
I am also building another set of speakers, these are also 100 dB efficient, but 5 ohm instead of 15 ohm. In my mind, the lower rails are better with lower impedance loads.
Used the seven dollar PEX EI unit in all versions of My_Ref. This is a 48 volt ct unit. It ends up at 34 volts using the SIP rectifiers. Using lower loss restifiers and the +/- 23 volt toriods should give about the same rail voltage.
Also I am now using a passive volume control with the monos. That is why I asked about driving the Evolution.
The passive uses LDR's and is better sounding than all the pots and setted attenuators I have tried as a passive in the past.. For some reason the LDR is more dynamic and has more color than the others. It may just be the lack of moving contacts, that is what others have commented.
George
Panelhead,
With 100db sensitivity speakers you will probably not need the Full version of the Evolution. Anyway, I get the feeling that Mauro prefers the Base version.
I see you are a very busy diy'er!
I probably need an external volume control to give me a finer range of control than the discrete resistor stepped volume control on the valve phono preamp that I've been using with the My_Ref. Maybe a Joshua Tree connected to the Tape Out RCAs would be a good choice?
Dynamics
I'm not so sure high dynamice are such a good thing. It may be impressive, but it can be unsettling to be continually startled (especially with the many audiophile vinyl records I have), and really makes it difficult to relax and enjoy the music. My wife is continually screaming to "turn it down", which I do, then I can barely hear the quiet passages.
I've been tinkering with a diy ss MC Head amp and my aim is to get a balanced sound. If that means high dynamics, so be it. If not, that is ok. and my wife will thank me.
Audie.
With 100db sensitivity speakers you will probably not need the Full version of the Evolution. Anyway, I get the feeling that Mauro prefers the Base version.
I see you are a very busy diy'er!
I probably need an external volume control to give me a finer range of control than the discrete resistor stepped volume control on the valve phono preamp that I've been using with the My_Ref. Maybe a Joshua Tree connected to the Tape Out RCAs would be a good choice?
Dynamics
I'm not so sure high dynamice are such a good thing. It may be impressive, but it can be unsettling to be continually startled (especially with the many audiophile vinyl records I have), and really makes it difficult to relax and enjoy the music. My wife is continually screaming to "turn it down", which I do, then I can barely hear the quiet passages.
I've been tinkering with a diy ss MC Head amp and my aim is to get a balanced sound. If that means high dynamics, so be it. If not, that is ok. and my wife will thank me.
Audie.