M'kay, that sounds like a plan. Thanks! You should get a nice order from me just as soon as some more money tick in.
Any tips on caps yet? Seems classd4sure is doing some testing here, but I've given up keeping track of it 🙂 And of course, there's the problem (or freedom) of choosing separate bass and mid/treble caps.
Any tips on caps yet? Seems classd4sure is doing some testing here, but I've given up keeping track of it 🙂 And of course, there's the problem (or freedom) of choosing separate bass and mid/treble caps.
classd4sure said:
I recognise that from my listning to one 700XE. Obviously these modules are as good as those and most likely even better!
Congratulations to your success and thanks for getting through all troubles you had with the testing!
Lars Clausen said:
Lars, I'm not an expert here, is the idle power about the same as traditional amps? Back in the early days we used similar technology to drive actuators to save power, are we still saving on power consumption here?
Lars Clausen said:btw here is the reason why a 'warmed up' amplifier sounds better than a cold one:
A typical capacitor characteristic, at higher temperatures, the ESR goes down due to the chemical bonding in the electrolytic fluid. From 25 to 55 degrees the ESR is halved, so it's a significant change.
I totally agree.
You could wire some turns of resistive wire around the cap body and feed it a few volts to warm it up to about 65 degrees....85 degrees might be too much because of diminishing life cycle.
Anzgar, 😉
Lars, I wouldn't rely too heavily on any sort of lowest thd claims, especially if alot of that is just thanks to high idle current which it seems to me just about any of the competing products on the market could easily do as well.
As per the comments about why an amp sounds better warming up, I think there's far better graphs to show the nature of ESR Vs Temperature.
http://www.chemi-con.com/u7002/applications.php
I do not dispute the change in ESR totally, however according to figure 23 and other graphs I've seen that I'd consider more relevant, the greatest change in ESR occurs over past sub zero temperatures, which unless you're building automotive amplifiers for this area, you can consider abnormal use conditions, being some 25 degrees below what you'd normally design for as being room temperature.
You can see from Figure 23 in the above link for instance that at 25 degrees C, and a very healthy margin above and below it, the change in ESR is far more less dramatic.
From the norm of 25 deg C in temp to what you decide is going to be the standard operating temperature for the amplifier and components in question, there's actually very little change in ESR, certainly nothing near "halving" by any means.
I also believe there's far more things occuring during the initial warm up period of any amplifier that affect the sound than are possibly worth attributing to the obvious minor change in ESR seen in caps.
Notably changes in semiconductor physics effecting performance, PCB material, parasitics, everything has to stabilize according to working conditions, including temperature. I've little doubt their tandem effect outweighs that of any one, otherwise it's probably not a very good design to start with. However caps do kind of make it or break it, but that won't change so much by just a few degrees either!
For instance why can't I just open a window or turn up the heat accordingly to do away with the signature I dislike in the FC's. It's likely not to be ESR related.
Also, Anzgar, it'd serve no useful means to invest in heating coils around the caps, unless done in such a way as to cancel their ESL, and for that reason alone, because their heating is already a self fulfilling prophecy, and the actual changes in temperature seen under normal use along with the established minor change in ESR at those given temperatures would make trying to stabilize it further a thankless venture.
I think I will try something different with the bypass caps today, moaners and grippers be damned, it's too good a learning oppertunity for me. I'm not forced to share the results though, don't worry.
Listening to the amps now as before reveals some flatness in the response of the highs.... lacks a sense of life/control, detail is extremely precise, you can distinguish echo's perfectly their fourth time over, but it's just overall a bit sloppy and laid back.
After I mess with the caps to fix that, I'll see how post filter feedback changes things as well.
Also, I'm confident that I'm enjoying the NCD modules more now that they're back on the less efficient sound dynamic speakers. From the listening position it makes them virtually silent. If you stick your ear next to them you still hear alot of noise from the source, which is at disturbing levels on my other speakers.
The high gain of the NCD amp really make it important to go with balanced inputs if you want to get the best from it, and best possible grounding arrangement as always. Without argument the UCD400's are alot quietter to plug in.
Also please note I never said anything like you'd need a turbine to cool these modules, simply stressed the importance of venting your case. I'm sure it would go much higher than 50 deg. if you didn't.
Cheers for now,
Chris
Lars, I wouldn't rely too heavily on any sort of lowest thd claims, especially if alot of that is just thanks to high idle current which it seems to me just about any of the competing products on the market could easily do as well.
As per the comments about why an amp sounds better warming up, I think there's far better graphs to show the nature of ESR Vs Temperature.
http://www.chemi-con.com/u7002/applications.php
I do not dispute the change in ESR totally, however according to figure 23 and other graphs I've seen that I'd consider more relevant, the greatest change in ESR occurs over past sub zero temperatures, which unless you're building automotive amplifiers for this area, you can consider abnormal use conditions, being some 25 degrees below what you'd normally design for as being room temperature.
You can see from Figure 23 in the above link for instance that at 25 degrees C, and a very healthy margin above and below it, the change in ESR is far more less dramatic.
From the norm of 25 deg C in temp to what you decide is going to be the standard operating temperature for the amplifier and components in question, there's actually very little change in ESR, certainly nothing near "halving" by any means.
I also believe there's far more things occuring during the initial warm up period of any amplifier that affect the sound than are possibly worth attributing to the obvious minor change in ESR seen in caps.
Notably changes in semiconductor physics effecting performance, PCB material, parasitics, everything has to stabilize according to working conditions, including temperature. I've little doubt their tandem effect outweighs that of any one, otherwise it's probably not a very good design to start with. However caps do kind of make it or break it, but that won't change so much by just a few degrees either!
For instance why can't I just open a window or turn up the heat accordingly to do away with the signature I dislike in the FC's. It's likely not to be ESR related.
Also, Anzgar, it'd serve no useful means to invest in heating coils around the caps, unless done in such a way as to cancel their ESL, and for that reason alone, because their heating is already a self fulfilling prophecy, and the actual changes in temperature seen under normal use along with the established minor change in ESR at those given temperatures would make trying to stabilize it further a thankless venture.
I think I will try something different with the bypass caps today, moaners and grippers be damned, it's too good a learning oppertunity for me. I'm not forced to share the results though, don't worry.
Listening to the amps now as before reveals some flatness in the response of the highs.... lacks a sense of life/control, detail is extremely precise, you can distinguish echo's perfectly their fourth time over, but it's just overall a bit sloppy and laid back.
After I mess with the caps to fix that, I'll see how post filter feedback changes things as well.
Also, I'm confident that I'm enjoying the NCD modules more now that they're back on the less efficient sound dynamic speakers. From the listening position it makes them virtually silent. If you stick your ear next to them you still hear alot of noise from the source, which is at disturbing levels on my other speakers.
The high gain of the NCD amp really make it important to go with balanced inputs if you want to get the best from it, and best possible grounding arrangement as always. Without argument the UCD400's are alot quietter to plug in.
Also please note I never said anything like you'd need a turbine to cool these modules, simply stressed the importance of venting your case. I'm sure it would go much higher than 50 deg. if you didn't.
Cheers for now,
Chris
Chris: Thank You for showing us this application note. It seems you have been spending some time trying to google something up to prove or disprove my claim about the capacitors ESR.
I didn't catch the ESR effect out of the blue, it came to my attention after digging down in the physics of capacitors, with help from two of the biggest experts on capacitor construction in the world. They happen to work for two different major capacitor manufacturers.
At low voltages (like 6,3 10 16V) the ESR effect is small, but increases with higher voltage. This has to do with the thickness of the paper, the etching structure of the foil, and also the actual electrolytic fluid. (Which is not the same for low and high voltage caps).
About the modules, play with them as you please, change the components you like, and what ever. But please don't report it here in the thread when you blow them up again
I thank you for your efforts to test the NCD, and from my point of view the test was a great success.
What ever further tests you might want to make with them, is your private matter. I consider these handmade prototypes now disposable, and due to excessive components changes, not to be considered reliable 'selling quality' modules. They have performed their expected task, with success, and are from my point of view now expired.
I didn't catch the ESR effect out of the blue, it came to my attention after digging down in the physics of capacitors, with help from two of the biggest experts on capacitor construction in the world. They happen to work for two different major capacitor manufacturers.
At low voltages (like 6,3 10 16V) the ESR effect is small, but increases with higher voltage. This has to do with the thickness of the paper, the etching structure of the foil, and also the actual electrolytic fluid. (Which is not the same for low and high voltage caps).
About the modules, play with them as you please, change the components you like, and what ever. But please don't report it here in the thread when you blow them up again
I thank you for your efforts to test the NCD, and from my point of view the test was a great success.
What ever further tests you might want to make with them, is your private matter. I consider these handmade prototypes now disposable, and due to excessive components changes, not to be considered reliable 'selling quality' modules. They have performed their expected task, with success, and are from my point of view now expired.
Your not offering to send any more out to us other testers then
Thanks for sharing the interesting info regarding capacitors Lars, I'm sure you've already tried all this stuff yourself anyway😉
Thanks for sharing the interesting info regarding capacitors Lars, I'm sure you've already tried all this stuff yourself anyway😉
Lars, is there any frequency response plots to be found anywhere at the NCD site? I know the text mentions 2~120KHz, but a Frequency+phase plot without data smoothing would be more informative. Some output impedance plots would also be nice to see.
Cris, I think removing dead time is always good. Especially at low level signals. One reason I don't like to just look at distortion data figures is that they are mostly sine wave based, and the signal levels are significantly large so that it effectively lowers the distortion numbers caused by dead time. Also I beleive it is possible to alter the DC content of the test signal to lower distortion figures.
I also wonder whether bolting that medal block to the chassis will be good enough for keeping the modules from getting hot. 50 degrees is really quite hot to the touch.
In respect to reviews, other components are also very important. The system performance is always revealing the weakest component in the link if the speakers can reveal enough. Some things may not be the quality of the amp, but other weak part as well. My experience is that if you flip the polarity at the speakers and you can clearly distinguish a difference, then you have speakers that can reveal many other things. REgarding how to find the weakest link in the system, well that's one too long for now.
Cris, I think removing dead time is always good. Especially at low level signals. One reason I don't like to just look at distortion data figures is that they are mostly sine wave based, and the signal levels are significantly large so that it effectively lowers the distortion numbers caused by dead time. Also I beleive it is possible to alter the DC content of the test signal to lower distortion figures.
I also wonder whether bolting that medal block to the chassis will be good enough for keeping the modules from getting hot. 50 degrees is really quite hot to the touch.
In respect to reviews, other components are also very important. The system performance is always revealing the weakest component in the link if the speakers can reveal enough. Some things may not be the quality of the amp, but other weak part as well. My experience is that if you flip the polarity at the speakers and you can clearly distinguish a difference, then you have speakers that can reveal many other things. REgarding how to find the weakest link in the system, well that's one too long for now.
Hi Lars,
I just don't think there's actually such an importance on ESR VS operating temperature/warm up. Bass for instance doesnt' improve significantly in the first few seconds of turning an amp on.
I've experienced it get a little bit cleaner if anything, but that's a change I found true across the whole audio spectrum (if any), if you're using caps that are partial to grain for instance, there be simply be less grain once warm, but if it only takes a few seconds to warm up .... how can you honestly know.
To say ESR is halved .... big deal, it changed 7.5mOhm, at their highest ESR it's probably still lower than that of the mosfets.
It's likely the physical changes within the ESR itself that has more to do with any sonic changes than ESR alone.
Also that graph of ESR VS frequency is less than believable, looks more like a marketting thing. You can see more believable graphs in the link I provided, and that's the reason for it.
Anyway, it is good to finally have permission to do with these modules as I please, after all I've licked them enough... considering everything that's occured with them.
I've yet to blow them up a first time though. I couldn't help but notice your use of the word "again". So to recap for the sake of clarity, one module was DOA, it then suffered a broken wire due to poor soldering and a resistor failure. If they faulter again I'll probably share that too. You did after all specifically ask me to share my experience with it, over the course of a year or so, that to me implies both good and bad. It got frustrating for a time as you can imagine because it was more bad than good, and I suppose that got reflected here. To avoid that you should have ensured they were in working order when they arrived and I don't think you actually did so.
The "extra testing" you said you did was most likely bringing the amp around for auditioning purposes than anything else, but it's pretty obvious to have a DC error of 20V on the output that keeps getting re-established every few seconds due to self resetting protection circuitry.
You also failed to answer any of my querries regarding their use, repair, my freedom to carry out those repairs, or further optimise their implementation. Any direct querry to those matters went ignored. Otherwise I'd have not gone against your wishes, like you said, it's your party.
You failed to instruct me to keep anything private, and further released information pertaining to the DOA incident on this thread yourself.
It seems to me that with every step you took, this is exactly what you signed on for. So I'm glad to finally get a little bit of feedback from you on the whole matter and that you'd consider it a success, which took alot of work/time on my part and which I took alot of flak over for it here too.
Anyway I now have a few comments, observations, and a question.
My comments as to whether or not I should share the results are a direct result of the endless criticism I've taken over every little thing from those who'd wish to be in my shoes with them.... and aren't satisfied it's not "review" enough for their liking. Whatever. So I do thank you for some much needed feedback, finally.
Observations:
The original SAL caps are indeed very similar to black gates, though I'd say SAL's are somewhat better still, but the black gates impart similiar properties on the audio.
The FC's, while I strongly disliked the color they imparted on the high's, were without doubt the most accurate/highest resolution cap I tried with them. Every nuance in the audio made it through, they made _alot_ of what I listened to a whole new experience that hasn't been seen since their removal.
With the FM's in place & stock caps found on the UCD module as local decoupling, it sounded alot more like a stock UCD, though not as holographic.. (post filter feedback.... bigger transformer??? I'll let you know eventually). Oddly, it also ran alot cooler with it! That was an unexpected result to say the least. They both have black gates now and are at the same hotter temperature.
The module with the black gates as local decoupling + FM really stood out for a few reasons though.
I can't say it was better, however there was a certain level of realism, mostly in the midrange, and some HF, that it did extremely well. Coupled with their infamous break in period, it made me curious enough to want to try them on both modules, and that's how they stand now.
My only beef with them would be they seem to require further HF bypassing.
In the end I'll probably end up with the FM's and film bypass.
Over all things one original problem still haunts me.
That is that one module has at least an order of magnitude more hiss than the other.
I believe I've located a resistor of incorrect value that explains this difference... I'd like to further discuss that matter with you Lars, so that I can get it replaced with the right one for both modules. While I do that I will also repair the burnt low value resistor of before which is currently simply shorted out.
It's all these little problems that have prevented me from giving a full head to toe review on the thing, that should have been worked out in the weeks prior to sending it to me, but I've attempted to repair, and implement them as best as possible along the way, sharing what valide impressions I thought I had, as much possible.
I don't feel my promise yet fulfilled. Nor do I feel it broken, or like I haven't kept up to my end of things. Since it was never discussed in email at all, will I still get replacement production versions.....? If so I'll let these suckers sit just like they are now... if not I'll continue to repair them and comment on my experience along the way.
Otherwise, would you like them back for sentimental value..... or would it be at all a bother to spot them on Ebay in a month or two from now? That I don't think would be very nice of me.
There's also the possibility to send it around to others as your demo amp once I'm done with it.....
All open for discussion .... if you ever think any of my questions are worth answering.
I just don't think there's actually such an importance on ESR VS operating temperature/warm up. Bass for instance doesnt' improve significantly in the first few seconds of turning an amp on.
I've experienced it get a little bit cleaner if anything, but that's a change I found true across the whole audio spectrum (if any), if you're using caps that are partial to grain for instance, there be simply be less grain once warm, but if it only takes a few seconds to warm up .... how can you honestly know.
To say ESR is halved .... big deal, it changed 7.5mOhm, at their highest ESR it's probably still lower than that of the mosfets.
It's likely the physical changes within the ESR itself that has more to do with any sonic changes than ESR alone.
Also that graph of ESR VS frequency is less than believable, looks more like a marketting thing. You can see more believable graphs in the link I provided, and that's the reason for it.
Anyway, it is good to finally have permission to do with these modules as I please, after all I've licked them enough... considering everything that's occured with them.
I've yet to blow them up a first time though. I couldn't help but notice your use of the word "again". So to recap for the sake of clarity, one module was DOA, it then suffered a broken wire due to poor soldering and a resistor failure. If they faulter again I'll probably share that too. You did after all specifically ask me to share my experience with it, over the course of a year or so, that to me implies both good and bad. It got frustrating for a time as you can imagine because it was more bad than good, and I suppose that got reflected here. To avoid that you should have ensured they were in working order when they arrived and I don't think you actually did so.
The "extra testing" you said you did was most likely bringing the amp around for auditioning purposes than anything else, but it's pretty obvious to have a DC error of 20V on the output that keeps getting re-established every few seconds due to self resetting protection circuitry.
You also failed to answer any of my querries regarding their use, repair, my freedom to carry out those repairs, or further optimise their implementation. Any direct querry to those matters went ignored. Otherwise I'd have not gone against your wishes, like you said, it's your party.
You failed to instruct me to keep anything private, and further released information pertaining to the DOA incident on this thread yourself.
It seems to me that with every step you took, this is exactly what you signed on for. So I'm glad to finally get a little bit of feedback from you on the whole matter and that you'd consider it a success, which took alot of work/time on my part and which I took alot of flak over for it here too.
Anyway I now have a few comments, observations, and a question.
My comments as to whether or not I should share the results are a direct result of the endless criticism I've taken over every little thing from those who'd wish to be in my shoes with them.... and aren't satisfied it's not "review" enough for their liking. Whatever. So I do thank you for some much needed feedback, finally.
Observations:
The original SAL caps are indeed very similar to black gates, though I'd say SAL's are somewhat better still, but the black gates impart similiar properties on the audio.
The FC's, while I strongly disliked the color they imparted on the high's, were without doubt the most accurate/highest resolution cap I tried with them. Every nuance in the audio made it through, they made _alot_ of what I listened to a whole new experience that hasn't been seen since their removal.
With the FM's in place & stock caps found on the UCD module as local decoupling, it sounded alot more like a stock UCD, though not as holographic.. (post filter feedback.... bigger transformer??? I'll let you know eventually). Oddly, it also ran alot cooler with it! That was an unexpected result to say the least. They both have black gates now and are at the same hotter temperature.
The module with the black gates as local decoupling + FM really stood out for a few reasons though.
I can't say it was better, however there was a certain level of realism, mostly in the midrange, and some HF, that it did extremely well. Coupled with their infamous break in period, it made me curious enough to want to try them on both modules, and that's how they stand now.
My only beef with them would be they seem to require further HF bypassing.
In the end I'll probably end up with the FM's and film bypass.
Over all things one original problem still haunts me.
That is that one module has at least an order of magnitude more hiss than the other.
I believe I've located a resistor of incorrect value that explains this difference... I'd like to further discuss that matter with you Lars, so that I can get it replaced with the right one for both modules. While I do that I will also repair the burnt low value resistor of before which is currently simply shorted out.
It's all these little problems that have prevented me from giving a full head to toe review on the thing, that should have been worked out in the weeks prior to sending it to me, but I've attempted to repair, and implement them as best as possible along the way, sharing what valide impressions I thought I had, as much possible.
I don't feel my promise yet fulfilled. Nor do I feel it broken, or like I haven't kept up to my end of things. Since it was never discussed in email at all, will I still get replacement production versions.....? If so I'll let these suckers sit just like they are now... if not I'll continue to repair them and comment on my experience along the way.
Otherwise, would you like them back for sentimental value..... or would it be at all a bother to spot them on Ebay in a month or two from now? That I don't think would be very nice of me.
There's also the possibility to send it around to others as your demo amp once I'm done with it.....
All open for discussion .... if you ever think any of my questions are worth answering.
I really feel sorry for Lars.
Lars, next time sent me the modules. 😀 I won't even announce a review until it's done, which is the right way to conduct it.
Lars, next time sent me the modules. 😀 I won't even announce a review until it's done, which is the right way to conduct it.
soongsc said:
See what I mean?
Everyone is crying for results, what's taking so long... why didn't you just plug it in... I was never asked to review but to share in my eperience with it, so by that time frame your "review" wouldnt' be out until next year, and there'd be alot of unhappy posts here.
Fact is I've delivered as promised, to the very best of my ability, and for the most part right on schedule. There's nothing to feel sorry for at all. I think the intention of Lars' last post was more to silence any further comments such as your own (sure, some from me too).
I was just in the process of typing a reply to your other post, which was interesting, but... good luck.
I, for one, have learned a lot in this thread, both about the NCD and general problems/improvements on classD amps. I haven't been around in these forums long enough to you or your preferences very well, classd4sure, but it seems to me you've addressed the problems and experiences - both positive and negative - in an objective and informative way. What issues you and LC may have had hasn't shown, unless I've turned very imperceptive 😉
Moving on, I'd very much appreciate it if you could write a litt round-up on all your experiences and mods, whether you keep working on the pre production units or get some new ones.
Thanks for everything so far!
Lars: Do you have any pictures of the production unit yet?
Moving on, I'd very much appreciate it if you could write a litt round-up on all your experiences and mods, whether you keep working on the pre production units or get some new ones.
Thanks for everything so far!
Lars: Do you have any pictures of the production unit yet?
Lars: Hi, i will take some tomorrow. Unfortunately it takes around 3-4 weeks for the cable company (TDC) to wire us up for ADSL in our new office. So i have to remember to take the camera home with me tomorrow evening, to upload the photos. So in case this goes as planned, you will have the photos tomorrow.
We completed the first two modules today, ready for shipping out. Tomorrow many more will follow.
We completed the first two modules today, ready for shipping out. Tomorrow many more will follow.
classd4sure said:
Maybe it's just my misunderstanding, but when I read that you were going to test the modules in the grand opening, I just got excited about the performance portion. I'm quite sure that Lars would have ment testing experience instead of tinkering experience.
If everyone else had access to the commercial product and could understand precisely which part of the circuit you're having problems with, then the way you are reporting it is good. Without access to the modules, many people probably would go to bed thinking "oh my god, so many problems" without any understanding whether it was the mod process that caused the problem or whether the product inherently has a problem, and I don't think anyone should criticise the circuit unless there is a published schematic to objectively talk about the issue.
Since the modules were given to you to get your hands on before commercial availability, it's just a matter of courtesy to hold off on public negative remarks until the problem is solved.
I really don't mind how people respond to my posts, but I think it's important to focus on the issue regardless who posts it. Light hearted jokes are of a different matter though.😀
Hi,
An odd occurance, I was just blasting this thing for someone and the protection circuitry tripped, under voltage maybe?? Rails must have sagged just enough I don't know...
The lights remained solidly lit, no flashing.. no sound.
Re-plug the amp and it worked fine. I'd like to know why 20Vdc output gets reset every second or two, while undervoltage, which really can't be that big a deal, certainly it's not DC output, results in forced user intervention. I think that's backwards.
It's not so mysterious that should occure as I'm sure it was hard clipping , but it was only cranked for a split second too, and I've run it much harder before with no such occurance. Perhaps it's also a low mains period.
I got some high quality pictures taken of it tonight, but it may take a little while to get them uploaded to a PC.
Cheers,
Chris
An odd occurance, I was just blasting this thing for someone and the protection circuitry tripped, under voltage maybe?? Rails must have sagged just enough I don't know...
The lights remained solidly lit, no flashing.. no sound.
Re-plug the amp and it worked fine. I'd like to know why 20Vdc output gets reset every second or two, while undervoltage, which really can't be that big a deal, certainly it's not DC output, results in forced user intervention. I think that's backwards.
It's not so mysterious that should occure as I'm sure it was hard clipping , but it was only cranked for a split second too, and I've run it much harder before with no such occurance. Perhaps it's also a low mains period.
I got some high quality pictures taken of it tonight, but it may take a little while to get them uploaded to a PC.
Cheers,
Chris
Chris, thanx for the time and effort to test these modules. You were open and honest here on the forum about what happened with these modules and I can only appreciate that. Also Lars is very open minded in this forum about the things that happened. I'll get the NCD's also when Lars is ready to ship and will compare them to the other ClassD products.
Bert
Bert
Hi Lars,
If it is a production like version you wanted evaluated... how come those panasonic FC caps don't look like the ones you sent me?
Nice addition of the header pins.
Cheers,
Chris
If it is a production like version you wanted evaluated... how come those panasonic FC caps don't look like the ones you sent me?
Nice addition of the header pins.
Cheers,
Chris
We found a way of using the 128SALRPM's again. They simply sound too good to design out.
There is also a plug for an optional separate analog powersupply (for the input stage).
There is also a plug for an optional separate analog powersupply (for the input stage).
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