2SK170 is not a direct substitution of 2N5565. Some modifications to the circuit will have to be made. 2N5565 is also a dual jfet in a metal can, a much better transistor than the plastic singe 2SK170. 2N5565s are available on eBay and at many other places. Not sure why anyone would want to use the 2SK170s.
Nagys.
I never said that it was but it will work if you bond the devices togther, match them and adjust the source resistance, in fact I dare say they probably will work better........ ..., being an engineer you should realize that. The question to you is why might the 2sk170's be better?
That being said my favorite device for the job is the 2sk389, if you can get them, a far superior device to the 2N5565 in this application.
Ostripper and I have tried to point out the flaws in the amp, which is far from perfect, what better place to start than the differential, there is nothing to be learned by merely cloning a device how about improving it, this is old technology here is and can be made much better.
There are no absolutes is audio...............the danger is assuming there is.
Jam
I never said that it was but it will work if you bond the devices togther, match them and adjust the source resistance, in fact I dare say they probably will work better........ ..., being an engineer you should realize that. The question to you is why might the 2sk170's be better?
That being said my favorite device for the job is the 2sk389, if you can get them, a far superior device to the 2N5565 in this application.
Ostripper and I have tried to point out the flaws in the amp, which is far from perfect, what better place to start than the differential, there is nothing to be learned by merely cloning a device how about improving it, this is old technology here is and can be made much better.
There are no absolutes is audio...............the danger is assuming there is.
Jam
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Maybe another thread should be made for "improving the goldmund" as it seems Nagys is completely against changing anything really on it. Most of you guys know way more then me about amp circuits and I feel that you are saying much can be improved on this design, frankly that's what I'd like to build an improved design.
Nagys want to build 'Goldmund' clone, without changing anything becouse he can sale clone for better price. There is no knowlage for improvement, and most suggestion are ignored.
BD249C/BD250C no need to be on heatsink, disipation is low and heatsink just warm it.
So, lets start one or more other threads, take a vote as to which design philosophy and direction the participants want to go in. No harm in choosing which road anyone wants to go in.
This is a free board and a consensus is the best way with those with super superior knowledge nudging and pushing the players in the right direction with TESTING and listening done until there is some satisfaction for all.
I would like to see a higher current handling double sided ground planed board with more output devices. maybe a workable way of trying different front ends and or VAS.
The cost of building this version as is, just to try it out, is prohibitive to me.
Any suggestions for a name for the improved version(s) thread name?
This is a free board and a consensus is the best way with those with super superior knowledge nudging and pushing the players in the right direction with TESTING and listening done until there is some satisfaction for all.
I would like to see a higher current handling double sided ground planed board with more output devices. maybe a workable way of trying different front ends and or VAS.
The cost of building this version as is, just to try it out, is prohibitive to me.
Any suggestions for a name for the improved version(s) thread name?
'Goldmund' is interesting only for one reason: PRICE $$$. There is nothing new in this old schematic. No need to start other threads, 'Goldmund' with 'improvements' already exist in other threads as amps with different names. 'Goldmund' name on 'Pioneer' DVD player have price X20.
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Attachments
Hi Alex,
1. Can you pls rotate the BSS74, 71 +90deg and move it up so they can be further away from the 100u/160v so as to cater for heatsinks if necessary. I had some 'sunflower' shaped heatsink that takes a lot less space than the 'star' you had some time ago.
2. The ground trace was squashed by the mounting holes which can be further apart by like 1-1.5". If you do that, the ground trace can be broaden. They can be moved apart and #3 can be done.
3. If you rotate the 10000uf on the right +90, while the one on the left -90, you should be able to broaden the -ve and +ve power traces too (with the ground moved already in #2).
4. Include some voids along the power and output rails just in case you might have to reinforce them.
5. The trace after the L1 seems to be way too thin. Also can you align the 2 (1 on main, 1 on daugther, well we don't know which is which, they are about the same size now) pads.
6. Can the trace from the Source to output rail be 'unsquashed' ?
Just my 2 cents opinion.
It also look as though all parts are in position, just wondering if we can start the GB?
1. Can you pls rotate the BSS74, 71 +90deg and move it up so they can be further away from the 100u/160v so as to cater for heatsinks if necessary. I had some 'sunflower' shaped heatsink that takes a lot less space than the 'star' you had some time ago.
2. The ground trace was squashed by the mounting holes which can be further apart by like 1-1.5". If you do that, the ground trace can be broaden. They can be moved apart and #3 can be done.
3. If you rotate the 10000uf on the right +90, while the one on the left -90, you should be able to broaden the -ve and +ve power traces too (with the ground moved already in #2).
4. Include some voids along the power and output rails just in case you might have to reinforce them.
5. The trace after the L1 seems to be way too thin. Also can you align the 2 (1 on main, 1 on daugther, well we don't know which is which, they are about the same size now) pads.
6. Can the trace from the Source to output rail be 'unsquashed' ?
Just my 2 cents opinion.
It also look as though all parts are in position, just wondering if we can start the GB?
Im by far not so smart and experienced as you are
and its a much much simpler curcuit
I moved outputs away from board, which means hardwired
turned everything on board upside down
And it did seem to make a few things much simpler
noteworthy is that the board doesnt need any high power rails
a ground lines are very simple
well, as said, its a simple design
one other option could be yet another simple board for the output devices only
a bit like Nelson's Burning amp designs
With his FirstWatt design he has also shown how a long slim board makes a neat and practial design
if nothing else, at least it wouldnt need very "high"(long) heatsinks
much easier to find a standard sized box with heatsinks, and cheaper
in other words, think more about final mounting, and the needed box design
and its a much much simpler curcuit
I moved outputs away from board, which means hardwired
turned everything on board upside down
And it did seem to make a few things much simpler
noteworthy is that the board doesnt need any high power rails
a ground lines are very simple
well, as said, its a simple design
one other option could be yet another simple board for the output devices only
a bit like Nelson's Burning amp designs
With his FirstWatt design he has also shown how a long slim board makes a neat and practial design
if nothing else, at least it wouldnt need very "high"(long) heatsinks
much easier to find a standard sized box with heatsinks, and cheaper
in other words, think more about final mounting, and the needed box design
Attachments
Guys, this amplifier sounds good because of the parts and the schematic it uses. If we start changing things around and replacing parts it will no longer be this incredible sounding amplifier. So what exactly is the point then? I posted this because I believe this to be the best sounding amp that I have ever heard and I did hear a lot of them. I heard amps from just about all major manufacturers.
Yes, I'm an engineer and that's exactly why I know that a military metal can dual jfet will sound significantly superior to a cheap plastic single jfet. If some people have a hard time believing, or understanding this, I'm not sure what else I can say to convince you. Metal can dual transistors will ALWAYS sound better than plastic single transistors, regardless of their specs. In addition, changing the 2N5565s to 2SK170s is not as easy as changin a few resistors.
If anyone wants to use the 2SK170s please do so. The PCB doasn't need to be changed for that. They will fit into the existing holes. This PCB is pretty standard in design, all the parts can be changed to whatever, so those who know what they're doing can upgrade as much as they desire. Until it no longer resembles a Goldmund amplifier.
Alex's PCB is the best one and it's the one to build. He has done an incredible amount of work. My only suggestions is that I would be against mounting the PCBs one on top of the other. I like the smaller protection circuit PCB and I would mount that adjacent to the main PCB. The only thing that I would like for Alex to try, if at all possible, is to mount the relay on the main board, so that the output signal doesn't have to travel to 2 different PCBs before it gets to the speaker terminals. That would make this design 100% perfect.
I also like bigpanda's suggestions. They should definitely be taken into consideration.
I'm ready for the group buy. I don't need any prototyping because I know this schematic inside out and know that it will work in Alex's PCB. If you guys want to wait, I have no problem with that either. I can build it first and let you all know how it performs. I will take 2 pairs of Alex's PCB and 2 Pairs of the smaller protection circuit PCB.
Yes, I'm an engineer and that's exactly why I know that a military metal can dual jfet will sound significantly superior to a cheap plastic single jfet. If some people have a hard time believing, or understanding this, I'm not sure what else I can say to convince you. Metal can dual transistors will ALWAYS sound better than plastic single transistors, regardless of their specs. In addition, changing the 2N5565s to 2SK170s is not as easy as changin a few resistors.
If anyone wants to use the 2SK170s please do so. The PCB doasn't need to be changed for that. They will fit into the existing holes. This PCB is pretty standard in design, all the parts can be changed to whatever, so those who know what they're doing can upgrade as much as they desire. Until it no longer resembles a Goldmund amplifier.
Alex's PCB is the best one and it's the one to build. He has done an incredible amount of work. My only suggestions is that I would be against mounting the PCBs one on top of the other. I like the smaller protection circuit PCB and I would mount that adjacent to the main PCB. The only thing that I would like for Alex to try, if at all possible, is to mount the relay on the main board, so that the output signal doesn't have to travel to 2 different PCBs before it gets to the speaker terminals. That would make this design 100% perfect.
I also like bigpanda's suggestions. They should definitely be taken into consideration.
I'm ready for the group buy. I don't need any prototyping because I know this schematic inside out and know that it will work in Alex's PCB. If you guys want to wait, I have no problem with that either. I can build it first and let you all know how it performs. I will take 2 pairs of Alex's PCB and 2 Pairs of the smaller protection circuit PCB.
One more thought... What do you guys think of the Zobel's location on this board? I think it should be right next to the series inductor on the output. Also, one wire will go from where the series inductor is to the + speaker terminal and then the - speaker terminal will connect to the ground, which is located on the other side of the board. I personally would prefer that these 2 connections were right next to each other. Just small nitpicks, but never the less would be nice. Not sure how difficult it would be to incorporate this into the PCB's design.
Alex's PCB is the one I like the most by FAR because the power supply should be on the same PCB, just like in Alex's design and the MOSFETS should also be mounted on the main PCB.
Alex's PCB is the one I like the most by FAR because the power supply should be on the same PCB, just like in Alex's design and the MOSFETS should also be mounted on the main PCB.
Agree with NAGYS, his purpose of sharing this schematic was that he believes that this is the best amp he has heard. Let's allow him to proto and then we can follow, although he has said that he has built this amp numerous times.
I am in no way against substituting components and modification to design but that is another issue, one that is too advance for my knowledge but I definitley listen to all the suggestions. This thread was started for this specific amp. Unless anyone else wants to share a schematic that they thinks is the best that they have heard.
I am still awaiting for OS to dial in his modular design that looks interesting also.
Who else here has heard this amp?
I am in no way against substituting components and modification to design but that is another issue, one that is too advance for my knowledge but I definitley listen to all the suggestions. This thread was started for this specific amp. Unless anyone else wants to share a schematic that they thinks is the best that they have heard.
I am still awaiting for OS to dial in his modular design that looks interesting also.
Who else here has heard this amp?
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