Very well said Sander,
I had strong doubts that an amp of this caliber would perform as depicted in the photos above. The clipping and stability behavior are among the first things looked at in any worthwhile design and I don't think it was neglected in this case.
lgreen don't take this the wrong way but something isn't right and you'll need to do some troubleshooting to locate the problem.
I had strong doubts that an amp of this caliber would perform as depicted in the photos above. The clipping and stability behavior are among the first things looked at in any worthwhile design and I don't think it was neglected in this case.
lgreen don't take this the wrong way but something isn't right and you'll need to do some troubleshooting to locate the problem.
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Sander,
Why don't you really say what you think? Just another bright guy, there are so many, who turns out NOT to have designed it anyway, who attacks with no deliberate provocation, to defend turf he never owned.
My comments were never a dig at your ability, rather, I praised you thinking you had designed and developed this amp in its entirety. In truth, you gave to understand that this design was yours. Now we find Bruno had a big hand in it; shame on you for not informing the forum of this fact, and shame on you for condemning Lgreen, who built your amp more than competently, sight unseen, in good faith, as an accessible, DIY design. Finally, your condemning me for incompetence demonstrates a total subjugation to ego and bile.
Your apology for rubbing folks up the wrong way is disingenuous, only fueling the bad feeling you have created here by blaming the messenger.
Now, why do you think it is oscillating? Can you answer this from the numerous photographs posted, as you intimate? Will you bother to identify the problems with the best Class A DIY design on the planet? Do you not consider that Lgreen deserves your attention? Or will you need to ask Bruno?
Why don't you really say what you think? Just another bright guy, there are so many, who turns out NOT to have designed it anyway, who attacks with no deliberate provocation, to defend turf he never owned.
My comments were never a dig at your ability, rather, I praised you thinking you had designed and developed this amp in its entirety. In truth, you gave to understand that this design was yours. Now we find Bruno had a big hand in it; shame on you for not informing the forum of this fact, and shame on you for condemning Lgreen, who built your amp more than competently, sight unseen, in good faith, as an accessible, DIY design. Finally, your condemning me for incompetence demonstrates a total subjugation to ego and bile.
Your apology for rubbing folks up the wrong way is disingenuous, only fueling the bad feeling you have created here by blaming the messenger.
Now, why do you think it is oscillating? Can you answer this from the numerous photographs posted, as you intimate? Will you bother to identify the problems with the best Class A DIY design on the planet? Do you not consider that Lgreen deserves your attention? Or will you need to ask Bruno?
??
To me the amplifier sounds very good. I will strive to provide additional differential and valid measurements.
However, this really bothers me-
What? We know Bruno designed this and you built and measured it (and probably did more, so no offense). The supplied parts list was incomplete to a "novice" such as myself. Specs, lead spacings and so on were not on it. See parts list on Post #205 and my comments. I never tried to do my own thing; I wanted to make it as he intended but I got nothing back; I was forced to measure every part with a set of calipers and set about to find the best part that matched and would fit the board. I emailed the OP my parts list with full hyperlinks to all parts to be used; I built a jig to match the critical transistors; I strived to implement the design that was set out and wanted ZERO deviation from the orignal. Yet I got no response. No "you are an ametuer" no "don't bug me" no "its ok" no nothing. No nothing.
And it turns out the OP doesn't have a working model for comparison. No working simulation for comparison. And there are no DC values to check. And this forum has never seen an orignal amp. You have seen modules of the PS and 1 amp channel (singular) but no complete amp in the original publication. No one has seen time domain measurements from the original. No one has seen the original clipping behavior.
So having no feedback I was forced to build it the way I built it with the parts on Post #10. And this is how it looks and came out. But this was not my intent: I asked and tried my hardest to make it the way it was supposed to be made; apparently without success given that the author's chose not to reply to my parts queries. And I used parts, like dual 700 VA transformers and more caps, that were far superior than thos used by the OP in the orignal article.
So we are at a stalemate- the OP and smart people (MJL) are saying that something must be wrong. What? Twisting the wires? I think its probably more than that this at this point.
I took 10MB photos of the boards and manually matched every resistor, transistor, diode and CRD based on its profile, labeling and color banding to ensure accuracy before starting this thread. All parts, to me, are exact. If a part is wrong is I will be shocked.
All DC values, to me, are exact. But we have no baseline to compare do we?
This is getting contentious and it should have never gotten this far. People should work together no? I am sorry that I will never be the engineer of Hough or the OP, but I did make this without help. Help would be appreciated now.
- lg
To me the amplifier sounds very good. I will strive to provide additional differential and valid measurements.
However, this really bothers me-
What? We know Bruno designed this and you built and measured it (and probably did more, so no offense). The supplied parts list was incomplete to a "novice" such as myself. Specs, lead spacings and so on were not on it. See parts list on Post #205 and my comments. I never tried to do my own thing; I wanted to make it as he intended but I got nothing back; I was forced to measure every part with a set of calipers and set about to find the best part that matched and would fit the board. I emailed the OP my parts list with full hyperlinks to all parts to be used; I built a jig to match the critical transistors; I strived to implement the design that was set out and wanted ZERO deviation from the orignal. Yet I got no response. No "you are an ametuer" no "don't bug me" no "its ok" no nothing. No nothing.
And it turns out the OP doesn't have a working model for comparison. No working simulation for comparison. And there are no DC values to check. And this forum has never seen an orignal amp. You have seen modules of the PS and 1 amp channel (singular) but no complete amp in the original publication. No one has seen time domain measurements from the original. No one has seen the original clipping behavior.
So having no feedback I was forced to build it the way I built it with the parts on Post #10. And this is how it looks and came out. But this was not my intent: I asked and tried my hardest to make it the way it was supposed to be made; apparently without success given that the author's chose not to reply to my parts queries. And I used parts, like dual 700 VA transformers and more caps, that were far superior than thos used by the OP in the orignal article.
So we are at a stalemate- the OP and smart people (MJL) are saying that something must be wrong. What? Twisting the wires? I think its probably more than that this at this point.
I took 10MB photos of the boards and manually matched every resistor, transistor, diode and CRD based on its profile, labeling and color banding to ensure accuracy before starting this thread. All parts, to me, are exact. If a part is wrong is I will be shocked.
All DC values, to me, are exact. But we have no baseline to compare do we?
This is getting contentious and it should have never gotten this far. People should work together no? I am sorry that I will never be the engineer of Hough or the OP, but I did make this without help. Help would be appreciated now.
- lg
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2 channels
Yes, both channels behave *exactly* the same. And both power supplies provide correct voltages and current. This was independently verified before hooking up the amp channels and then verified again.
And after looking at the original measurements, I took a week to verify each and every piece on those amp boards was correctly installed in the right location and in the right orientation; both visually via hires photos (markings, orientation and color bands) and electrically (volts) as best I could not having any DC baseline from the original poster (OP). And during the original installation and soldering I checked every part against a check list of the installed part matching (1) the part list (2) the schematic, (3) the label on the part, and (3) the measured value (resistors, etc).
It took 2 weeks to install the parts vs. the parts list, and another week to verify via applied power, and then another week to verify via hires photos.
The point is that everything I did was carefully done to be exact with multiple checkpoints. I am not saying that I couldn't have made a mistake but if I did I would not know where. I didn't just slap this thing together. It took a long time and a LOT of effort; every part was examined many times; every wiring decision was revisited.
And lets hear from Bruno. I would like an indication of what the time domain measurements should look like. That is assuming anyone looked at them before I did. Simulated or real.
Yes, both channels behave *exactly* the same. And both power supplies provide correct voltages and current. This was independently verified before hooking up the amp channels and then verified again.
And after looking at the original measurements, I took a week to verify each and every piece on those amp boards was correctly installed in the right location and in the right orientation; both visually via hires photos (markings, orientation and color bands) and electrically (volts) as best I could not having any DC baseline from the original poster (OP). And during the original installation and soldering I checked every part against a check list of the installed part matching (1) the part list (2) the schematic, (3) the label on the part, and (3) the measured value (resistors, etc).
It took 2 weeks to install the parts vs. the parts list, and another week to verify via applied power, and then another week to verify via hires photos.
The point is that everything I did was carefully done to be exact with multiple checkpoints. I am not saying that I couldn't have made a mistake but if I did I would not know where. I didn't just slap this thing together. It took a long time and a LOT of effort; every part was examined many times; every wiring decision was revisited.
And lets hear from Bruno. I would like an indication of what the time domain measurements should look like. That is assuming anyone looked at them before I did. Simulated or real.
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So it is not the layout, the parts choices, or the execution? Could it be signal wires crossing AC power cables? We must assume that since Bruno Putzneys designed it, the potential is there for a world beater, so it must be something small.
If both channels are misbehaving, it could be a design issue. Has Sander built the prototype and tested it the same way? Do your tests replicate his?
Compensation was arrived at via simulation, or empirically? What sort of comp caps were used, silver mica?
Sander, can you come in with any suggestions?
Hugh
If both channels are misbehaving, it could be a design issue. Has Sander built the prototype and tested it the same way? Do your tests replicate his?
Compensation was arrived at via simulation, or empirically? What sort of comp caps were used, silver mica?
Sander, can you come in with any suggestions?
Hugh
Well since you are the first person here to build one of these beasts, look on
the + side, it works and it hasn't blown up - give yourself a pat on the back!
- How did you go with the IP wave form. Is the square wave clean
going into the amp? Did you check both phases?
- Where / how is your cro grounded? I have had cases when the cro
ground has formed a large loop which caused some instability.When
measuring the amps OP try unclipping the probes earth clip or inserting a
few ohms in series with it.
- Is there any chance you can do a simple sketch of the IP, OP, PSU and
grounding layout, scan & post it here?
Most likely all that is required are some small adjustments.
T
the + side, it works and it hasn't blown up - give yourself a pat on the back!
- How did you go with the IP wave form. Is the square wave clean
going into the amp? Did you check both phases?
- Where / how is your cro grounded? I have had cases when the cro
ground has formed a large loop which caused some instability.When
measuring the amps OP try unclipping the probes earth clip or inserting a
few ohms in series with it.
- Is there any chance you can do a simple sketch of the IP, OP, PSU and
grounding layout, scan & post it here?
Most likely all that is required are some small adjustments.
T
1. Bruno knows his stuff- reason why I spent over $1000 to build this.
2. The OP did not show any measurements of time domain, its all THD and so forth. I am not able to replicate the same tests. Yes, his equip was and is far superior.
3. Comp caps are in my parts list; I think that they are silver mica. But it would be good if someone actually went over the parts I actually used as I requested long ago. Certainly the original parts were not specified as silver mica by the OP.
Full images in my footer.
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Hugh,
I find your reply a little offensive, but I'll give you the courtesy of a reply. This design was done by Bruno and me together, he did most of the raw design work, I did all the simulations, the testing, the prototypes, etc. etc. So this is as much my design as it is his, we both put about a year's work into it, hence I'm perfectly qualified to post here and comment on someone else's work.
Cheers,
Sander.
I find your reply a little offensive, but I'll give you the courtesy of a reply. This design was done by Bruno and me together, he did most of the raw design work, I did all the simulations, the testing, the prototypes, etc. etc. So this is as much my design as it is his, we both put about a year's work into it, hence I'm perfectly qualified to post here and comment on someone else's work.
Cheers,
Sander.
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Well, I have my doubts about execution, just look at the wire spaghetti, the way the output transistors are mounted (long leads) etc.
It is *not* a design issue, various prototypes were built that performed in line with the simulations and expectations. The published numbers are real, not fiction.
What do you think? I already mentioned ruthless real world testing and optimization on the prototypes. Silver mica isn't needed, simpe NP0 or C0G capacitors will do, that's what we used.
It is hard to make out exactly was is going on amidst the wire spaghetti. I'm sorry, but that's just not how this amplifier, or any amplifier for that matter, is supposed to be built. If Lgreen has access to some real measurement equipment, not a 30-year old scope which hasn't seen calibration or a checkup for decades, I'm not going to be able to offer much help.
As mentioned I'm building up a set of ExtremA's myself as well, I'll document the process in a new topic and show how it is supposed to be built. At that point I'm happy to compare notes with Lgreen. Unfortunately I don't have time to debug Lgreen's design at this point, as I'm a busy guy at work, with a very busy personal agenda as well.
Cheers,
Sander.
Sander,
Thank you for your reply.
The post was strongly suggesting that you really should help this man, make the small amount of time it will require, at least answer his basic queries. He has spent a lot of money and time building something you feel is the best thing since sliced bread. Moreover, a curt reply is entirely appropriate when you imply that someone you have never met is incompetent. No one here has said or implied that of you, and in truth, this is surprising.
What is at issue is the assistance he should reasonably expect from you.
Putting the blame on old, uncalibrated CROs is just absurd. The problem is a poor square wave at 20KHz, and bursts of oscillation, plainly visible. Your design, you do not wish to help, and start with ridicule. How does that look? The design, layout, or whatever, should be addressed with some useful suggestions until these gross issues are eliminated. Your credibility is at stake here, too.
Think about dignifying Lgreen's request with a little email assistance. It won't kill you, even if you are a busy, busy guy....... it is always best to be helpful and humble.
Thank you for your reply.
The post was strongly suggesting that you really should help this man, make the small amount of time it will require, at least answer his basic queries. He has spent a lot of money and time building something you feel is the best thing since sliced bread. Moreover, a curt reply is entirely appropriate when you imply that someone you have never met is incompetent. No one here has said or implied that of you, and in truth, this is surprising.
What is at issue is the assistance he should reasonably expect from you.
Putting the blame on old, uncalibrated CROs is just absurd. The problem is a poor square wave at 20KHz, and bursts of oscillation, plainly visible. Your design, you do not wish to help, and start with ridicule. How does that look? The design, layout, or whatever, should be addressed with some useful suggestions until these gross issues are eliminated. Your credibility is at stake here, too.
Think about dignifying Lgreen's request with a little email assistance. It won't kill you, even if you are a busy, busy guy....... it is always best to be helpful and humble.
Hugh,
I've already offered my support, but only *after* having completed my own build, so we can compare notes. I don't have an ExtremA built up at this point, hence can't go around doing measurements. Sure, I can fire up the simulator and offer some suggestions from the DC operating points found there, but I'd rather do a real world comparison.
And yes, I don't trust the measurement equipment used. I've personally experienced too many times that people go on a wild goose chase because the equipment is out of order, or the person operating it is operating it wrongly.
And no, I'm not putting the blame on Lgreen completely, but at this point I have a few known and tested facts, myself, our prototypes, the final design, and a few unknown variables which is Lgreen, his build and design choices made. Unless I can hop on over to his place and eyeball the build directly and fiddle around with it for a bit there's not a whole lot I can do.
I'd suggest he starts by checking parts and parts values again, shortens the output transistor leads and reduces the build down to something which is representative of a typical build. There's too many external components (caps, resistors, etc.) bolted on now that are not a part of the original design. I'd even go as far as to suggest reducing the bias current to 20W/8-ohm, just to debug the build and then switch back to 100W/8-ohm after all issues have been found and dealt with.
Again, due to the complexity this is not an amp meant for the novice builder. If one of the cascode transistors is stuffed wrong for example it could just run, but have abyssmal performance.
@lgreen, sorry buddy, I don't mean to crack down on your build, but from an engineer's point of view you've basically built the soapbox equivalent of a F1 racecar. Maybe we should go over the parts list, or maybe I should send some high resolution photos of the PCBs I've built up previously?
Cheers,
Sander.
I've already offered my support, but only *after* having completed my own build, so we can compare notes. I don't have an ExtremA built up at this point, hence can't go around doing measurements. Sure, I can fire up the simulator and offer some suggestions from the DC operating points found there, but I'd rather do a real world comparison.
And yes, I don't trust the measurement equipment used. I've personally experienced too many times that people go on a wild goose chase because the equipment is out of order, or the person operating it is operating it wrongly.
And no, I'm not putting the blame on Lgreen completely, but at this point I have a few known and tested facts, myself, our prototypes, the final design, and a few unknown variables which is Lgreen, his build and design choices made. Unless I can hop on over to his place and eyeball the build directly and fiddle around with it for a bit there's not a whole lot I can do.
I'd suggest he starts by checking parts and parts values again, shortens the output transistor leads and reduces the build down to something which is representative of a typical build. There's too many external components (caps, resistors, etc.) bolted on now that are not a part of the original design. I'd even go as far as to suggest reducing the bias current to 20W/8-ohm, just to debug the build and then switch back to 100W/8-ohm after all issues have been found and dealt with.
Again, due to the complexity this is not an amp meant for the novice builder. If one of the cascode transistors is stuffed wrong for example it could just run, but have abyssmal performance.
@lgreen, sorry buddy, I don't mean to crack down on your build, but from an engineer's point of view you've basically built the soapbox equivalent of a F1 racecar. Maybe we should go over the parts list, or maybe I should send some high resolution photos of the PCBs I've built up previously?
Cheers,
Sander.
Lgreen,
How about we start with looking at your PCBs and the parts stuffed, do you mind sending me some high-res photos? You have the email address. Sorry for being a d*ck, but I tend to not respond well to people criticizing a design that we've poured blood, sweat and tears into and is known to work well with all of the iterations we've built over the course of a year's development.
Cheers,
Sander.
How about we start with looking at your PCBs and the parts stuffed, do you mind sending me some high-res photos? You have the email address. Sorry for being a d*ck, but I tend to not respond well to people criticizing a design that we've poured blood, sweat and tears into and is known to work well with all of the iterations we've built over the course of a year's development.
Cheers,
Sander.
Thanks
Thanks! that is why my original post says "whew" meaning working and not blown up.
Thanks! that is why my original post says "whew" meaning working and not blown up.
testing
You know, when I started this amp, I thought the design was "in the can" and well tested and proven. I was never out to be on the cutting edge.
So now it turns out no one in the world has one up and running and even the original designer doesn't know the DC values and cannot show the signals as they go about their way through the amp. All wiring, components, measurements and measurement techniques are suspect. Yet no commentary on the technical details of what should appear where.
That's ok, it seems to work and I've got time to wait for others to complete theirs. Not like I am hurting for amps over here.
Nothing gets unsoldered until I see some measurements and DC values from others who have one of these up and running; happy to compare notes.
You know, when I started this amp, I thought the design was "in the can" and well tested and proven. I was never out to be on the cutting edge.
So now it turns out no one in the world has one up and running and even the original designer doesn't know the DC values and cannot show the signals as they go about their way through the amp. All wiring, components, measurements and measurement techniques are suspect. Yet no commentary on the technical details of what should appear where.
That's ok, it seems to work and I've got time to wait for others to complete theirs. Not like I am hurting for amps over here.
Nothing gets unsoldered until I see some measurements and DC values from others who have one of these up and running; happy to compare notes.
Lgreen,
Nonsense! There's quite a few people that have one running as I have sold over 25 sets of PCBs. I know of two for example that are used at a US university as a power measurement amplifier, as it packs quite a bit more grunt that the typical 2W a measurement amplifier puts out. Obviously there's also several people that are just using them for music playback. I have two friends that have them running here in Holland.
None of these folks have had any issues, and especially the ones used at the university have been measured front to back to validate our published specifications. All of these folks built it from stock components, and their ExtremAs have been running without fault. None of these folks however frequent here, or even know of DIYaudio forum's existence. Nor do I keep records of people that built them.
I personally haven't had a use for them, as they're rather large, due to the heatsink requirements, run hot and consume quite a bit of power. I've been happy with another design of Bruno's, a UcD class-D amplifier which is running stone cold.
Hence your case is an isolated one, which although unfortunate, doesn't justify the generalization that the design is flawed, or that no one else has built one yet.
Cheers,
Sander.
Nonsense! There's quite a few people that have one running as I have sold over 25 sets of PCBs. I know of two for example that are used at a US university as a power measurement amplifier, as it packs quite a bit more grunt that the typical 2W a measurement amplifier puts out. Obviously there's also several people that are just using them for music playback. I have two friends that have them running here in Holland.
None of these folks have had any issues, and especially the ones used at the university have been measured front to back to validate our published specifications. All of these folks built it from stock components, and their ExtremAs have been running without fault. None of these folks however frequent here, or even know of DIYaudio forum's existence. Nor do I keep records of people that built them.
I personally haven't had a use for them, as they're rather large, due to the heatsink requirements, run hot and consume quite a bit of power. I've been happy with another design of Bruno's, a UcD class-D amplifier which is running stone cold.
Hence your case is an isolated one, which although unfortunate, doesn't justify the generalization that the design is flawed, or that no one else has built one yet.
Cheers,
Sander.
Fair enough- there are at least 3 (EDIT- 4). Glad to hear it. (If you don't mind please email me the name of the US University; if you don't feel comfortable about this, that is ok too.)
Now lets see if we can work together to figure out what is going on.
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