Now now, no need to get excited over this, no need for strong words.
Quoting me that way is not fair, because that is not what I said.
I do not want to clone the original, I want a goldmund-like amp. But if we are not careful it will not be a Goldmund-like amp, but a totally different one.
If you look at the tread title it says "Goldmund Mods, Improvements, Stability" and to me that means that we should try not to depart from that design too much, don't you agree?
And I think design by committee is inherently bad if there is no-one to make decisions in the end. Committee research as you call it is fine.
This is Kean's thread, I think he should make the call. It is true what Jam says, this thread may go nowhere, but a lot of good information was passed and still will be passed, everyone goes away a little richer.
Every thread does not result in a build. I already have a garage full of amps, I take that most of us have, but because were are fanatics, we will try another idea regardless whether we get to Utopia. We know Utopia does not exist but heck what else is there to believe in.
If you have the best wife in the world, you may sometimes wonder; If I had waited a little longer maybe a better one came on offer.
On the other hand what if a better one did not came along and the one you have now was claimed by another. Where would you be then? - probably a happy, wealthy, un-stressed bachelor, but you will still wonder...
Every thread does not result in a build. I already have a garage full of amps, I take that most of us have, but because were are fanatics, we will try another idea regardless whether we get to Utopia. We know Utopia does not exist but heck what else is there to believe in.
If you have the best wife in the world, you may sometimes wonder; If I had waited a little longer maybe a better one came on offer.
On the other hand what if a better one did not came along and the one you have now was claimed by another. Where would you be then? - probably a happy, wealthy, un-stressed bachelor, but you will still wonder...
Ok point taken, I just wanted to throw in MY 2cts (how ironic haha).
I still think that if we wanted to design a completely different amp THAT should be in a different thread but the line is vague, then we'd have three threads:
a) Cloning the Goldmund as close to the original as possible (nagy's thread)
b) Fixing the flaws in the Goldmund design while staying faithful to the original (this thread)
c) Using the Goldmund as a basis for a new design.
Anyway, those are my
Carry on, carry on.
I still think that if we wanted to design a completely different amp THAT should be in a different thread but the line is vague, then we'd have three threads:
a) Cloning the Goldmund as close to the original as possible (nagy's thread)
b) Fixing the flaws in the Goldmund design while staying faithful to the original (this thread)
c) Using the Goldmund as a basis for a new design.
Anyway, those are my
Carry on, carry on.
Mace,
Besides, there is absolutely no guarantee that anything discussed here will sound any better or worse, unless we are all thoroughly familiar with how the goldmund performs and we are in agreement that we all share the same perception as well as know what we intend improving on. This is as good as it gets.
Besides, there is absolutely no guarantee that anything discussed here will sound any better or worse, unless we are all thoroughly familiar with how the goldmund performs and we are in agreement that we all share the same perception as well as know what we intend improving on. This is as good as it gets.
Well here is the magical formula quoted from the goldmund thread, maybe the electronics is not that important at all, it is all in the mechanics..... Here we have it in a nutshell!
Goldmund was a strong believer in the theory that current caused vibration in electrical components and power supplies leads to 'dramatically deteriorated' sound quality.
In the brochure that was posted earlier, they claim to have been befuddled as to why the high current version of the Mimesis sounded poorer and it was when they used the mechanical grounding the magic came back. They did things like heavily potting the torroids to reduce vibration, coupling the torriods and output stage directly to the anti virbation feet. The chassis was decoupled from the vibration feet via teflon insulators.
Then there is the issue of the input stage. Nagys seems to think the input stage was on it's own board and potted to keep it secret. But according to Goldmund, the input stage is very sensitive to microphony effects and was deliberately decoupled from the rest of the curcuit and outpage stage vibrations. Nagys could be right, but Goldmunds own literature regards this as an important part of the mechanical grounding implementation, and the picture of the newer Telos amplifiers shows the same exact same thing, an input stage on it's own board. (but with no potting)
Goldmund was a strong believer in the theory that current caused vibration in electrical components and power supplies leads to 'dramatically deteriorated' sound quality.
In the brochure that was posted earlier, they claim to have been befuddled as to why the high current version of the Mimesis sounded poorer and it was when they used the mechanical grounding the magic came back. They did things like heavily potting the torroids to reduce vibration, coupling the torriods and output stage directly to the anti virbation feet. The chassis was decoupled from the vibration feet via teflon insulators.
Then there is the issue of the input stage. Nagys seems to think the input stage was on it's own board and potted to keep it secret. But according to Goldmund, the input stage is very sensitive to microphony effects and was deliberately decoupled from the rest of the curcuit and outpage stage vibrations. Nagys could be right, but Goldmunds own literature regards this as an important part of the mechanical grounding implementation, and the picture of the newer Telos amplifiers shows the same exact same thing, an input stage on it's own board. (but with no potting)
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One thing to improve is, as the thread title says, stability. Keep the slew rate at least equal but is stable enough to remove the output coil. Such small thing will be a HUGE improvement!!
To achieve the stability with a high slew rate, the designer might be tempted to remove the driver stage, resulting in the topology used by Nico Ras. Damn, didn't I tell you that I have a faith in this extra stage (And where is Ostripper, why not check how the CXFET may turn out to be!!!). And Goldmund already did what it has to do
If input stage has to be kept, I'm worrying the JFET performance if not 2N5565. The CCS we can change to a "better" one. Probably a led based CCS. If anyone wants a K170 JFET input, I'll say I prefer a BJT input, but must be low noise with high fT (actually no need high fT as long as 100V/us can be achieved
). Matching is necessary so MAT03 is prime but difficult to source (I lost one so cannot build a stereo )The rail voltage should be chosen so we can choose to operate a superior transistor, may be with special heatsink for the driver, more class-A bias option, and of course keeping the slew rate at standard (100V/us).
Regulation, that's an important part, but could be part of individual implementation.
That's not a secret. I have been using individual implementation as a CRITICAL factor to have a superior amp, regardless the schematic. First, I'll do point-to-point with short signal path (as neat as possible so any cdom/comp can be reduced). Then matching and choosing optimum fT/hfe for the transistors. I measure the output Vgs in situ, and swap if not already matched. Then regulator types (front end regulation is a must), usualy low impedance. Low impedance supply caps, MKT bypass (values are also chosen). Superior diodes. High current transformer. Grounding. If size is not important, EI transformer can be used in separate compartment. And many other voodoos
Regarding mechanics I personally don't believe in damping, but I strongly believe in tuned mechanical grounding...This to the point where i dare to say that you have not really heard your amplifier until it's placed in an appropriate rack and fitted with good resonance control devices..
Other thing that often compromise sound is terrible earthing schemes..This is not only hum related....but if grounds is not kept clean an utterly stable.. then signal transfer between the units has tough working conditions...Bit like playing ball on a shaky wall..ball seems to bounce in all directions...So for sure in making the amplifier sing this issue must also be addressed in the very best way possible...so ground currents and ground potentials must be approaching 0.
Other thing that often compromise sound is terrible earthing schemes..This is not only hum related....but if grounds is not kept clean an utterly stable.. then signal transfer between the units has tough working conditions...Bit like playing ball on a shaky wall..ball seems to bounce in all directions...So for sure in making the amplifier sing this issue must also be addressed in the very best way possible...so ground currents and ground potentials must be approaching 0.
Hi Nico,
It seems as if you agree very much with Agisthos writing in "the other thread" about Goldmund. Have a look at post # 730:
http://www.diyaudio.com/forums/solid-state/174468-very-best-amplifier-i-have-ever-heard-73.html
Karsten ;-)
'Tuned"
like a car ?? Refined would be a good word for it. Dirty grounds and clean grounds , even mechanical grounds (heatsinks/chassis). No reason to make an amp with -120db distortion components if the ground reference is faulty. I have run my simulations on all the variants of this topology and there are BIG differences. (PIX1) is the original with and without a VAS cascode , using both the original devices and the fairchild's.(pix2) is with Nico's mods (different amp, essentially) and the figures get wild (real low) I actually pulled off .0005%- 20khz at over 100v p-p with the circuit in (PIX3)... a new record at that level.
It has 120v/us symmetrical slew ...fast as hell. ( PIX 3/4) is the circuit and crazy THD@ 10K- "normal levels". With a Jfet input and cascode it performs almost as well.Definitely a "strait vanilla" amp ... 26 PPM/10K even !!
When I make the board ,A "3 in one" universal voltage board (jumpers - extra pads) will be the way, allowing for any and all mods shown above. Then one can hear these plots for real.
OS
Attachments
Hi Karsten, I mention this because for some reason other than electronic this amp (to Nagys) sounds the best in the world - no sarcasm intended.
What about splitting the amplifier and power supply into two separate units and we tackle the PSU first to get the quietest very stable power from it. What I have found works well in the past is to use two separate transformers for each rail. The two toroidal transformers are mounted on top of each other and wired anti-phase from the mains. This cancels any stray magnetic fields. Then we place a steel housing over them and pot them so there is little mechanical vibration inside.
Therefore each amp will have two transformers (made into one) and two separate secondaries, each connected to a 35 Amp diode bridge with decoupling capacitors. Alternatively a bunch of fast diodes on a PCB. followed by the capacitor bank for each amp consisting of a PCB containing several capacitors to make up the required Joule and ripple current to supply the amplifier driving the lowest load (2 ohm) at full power.
Also contained inside the case will be a conducted EMI filter (commercial type) and a DC decoupling board to remove any DC off-set in the mains as well as MOVs to suppress any switching transients that may be present.
Mains earthing would be applied to the power supply casing, but the DC side will float from the mains earth. There is no legal or safety requirement that the DC side of the power supply has to be earthed in any way.
Also this box will contain the regulators for each amplifier on a sparate board should some not want them.
The power supply chassis would sit on vibration canceling feet that would decouple the box from the hi-fi stand so that no mains introduced mechanical vibration could couple into the hi-fi stand.
How am I doing so far?
Nico
Therefore each amp will have two transformers (made into one) and two separate secondaries, each connected to a 35 Amp diode bridge with decoupling capacitors. Alternatively a bunch of fast diodes on a PCB. followed by the capacitor bank for each amp consisting of a PCB containing several capacitors to make up the required Joule and ripple current to supply the amplifier driving the lowest load (2 ohm) at full power.
Also contained inside the case will be a conducted EMI filter (commercial type) and a DC decoupling board to remove any DC off-set in the mains as well as MOVs to suppress any switching transients that may be present.
Mains earthing would be applied to the power supply casing, but the DC side will float from the mains earth. There is no legal or safety requirement that the DC side of the power supply has to be earthed in any way.
Also this box will contain the regulators for each amplifier on a sparate board should some not want them.
The power supply chassis would sit on vibration canceling feet that would decouple the box from the hi-fi stand so that no mains introduced mechanical vibration could couple into the hi-fi stand.
How am I doing so far?
Nico
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So there will be boards for:
1. Front end, Input with FET or bipolar and VAS Mosfet or bipolar
2. Back end, either FET or BiPolar, with emitter resistors or not, 3, 4, or more pair
3. Great Front power supply or what ever
4. Standard Backend supply or enhanced
5. Protection or none needed
6. Total IR remote control with lots of LED's and shock absorbers...just kidding
Focus Focus FOCUS
1. Front end, Input with FET or bipolar and VAS Mosfet or bipolar
2. Back end, either FET or BiPolar, with emitter resistors or not, 3, 4, or more pair
3. Great Front power supply or what ever
4. Standard Backend supply or enhanced
5. Protection or none needed
6. Total IR remote control with lots of LED's and shock absorbers...just kidding
Focus Focus FOCUS
First 2 pictures show that I do not consider microphonics as audiophile "puffery". I have had my high gain "blameless" actually exhibit this while the input stage was tapped with a screwdriver. With this amp, placing it on a speaker un- isolated had a detrimental effect on the resulting sound. The isolation feet on the Genesis case plus the foam on the toroid totally cancelled out this "effect" when I tested at 200W+ with the room "a shakin' "
On my initial test bed (pix 3/4) ,I will even consider a neoprene mat to isolate my creations from the environment. I have 2 trafo's to separate the rails(voltage stage/ power stage) in my R and D setup (pix4) and will make a mini version of Nico's regulated PSU to fire up the voltage boards. If only I had some laterals , I could go "all the way".
OS
On my initial test bed (pix 3/4) ,I will even consider a neoprene mat to isolate my creations from the environment. I have 2 trafo's to separate the rails(voltage stage/ power stage) in my R and D setup (pix4) and will make a mini version of Nico's regulated PSU to fire up the voltage boards. If only I had some laterals , I could go "all the way".
OS
Attachments
What have I done
I actually intend to have the answer to all this "flurry ,bluster,yammering".. 2 huge threads (277+731 posts) , many conflicting ego's.
I am curious , but do not want to break the bank to develop better circuits. Unproven designs , group buys for circuits that are not even out of the R / D phase. Give me a break !!!Trafo with one wire ... he he...
Electrons are teleported to the amp. VOODOO!!
OS
