classd4sure said:
Probably, but a little overkill is fun sometimes.
I think I can borrow a couple of 600VA 40+40V ouput transformers from a friend, so hopefully I'll be able to experiment with these as well. It would be nice if the finished amp ends up being smaller than the current configuration but I will not sacrifice any sound quality to do so. I kind of put my experimenting on hold over the holidays. I guess I should get going on this.
Yeh ok,
I woulnd't say you're there yet with a 1000W amp at 100VA though. Regulation factor, current... etc.
I guess what I meant was the extreem end of it, the -3db point of diminished returns, where more gets you nothing .
With a 1000W amp, what do you get with a bigger transformer than 1000VA? Tighter regulation? Probably not.. current? None that you can use..
With caps... 20 000 to 30 000 seems to be the agreed limit, without power factor correction.
I woulnd't say you're there yet with a 1000W amp at 100VA though. Regulation factor, current... etc.
I guess what I meant was the extreem end of it, the -3db point of diminished returns, where more gets you nothing .
With a 1000W amp, what do you get with a bigger transformer than 1000VA? Tighter regulation? Probably not.. current? None that you can use..
With caps... 20 000 to 30 000 seems to be the agreed limit, without power factor correction.
Ok,
I would argue that if at 1000VA you dont' have that last 1%, a 2000VA wont' help you either, but it won't hurt anything other than your pocket book and possibly your back.
Now caps are a different story.
Going bigger than required will hurt performance.
So I look forward to the results with the smaller caps.
I would argue that if at 1000VA you dont' have that last 1%, a 2000VA wont' help you either, but it won't hurt anything other than your pocket book and possibly your back.
Now caps are a different story.
Going bigger than required will hurt performance.
So I look forward to the results with the smaller caps.
Hi,
is the difference of the before/after-sounds measurable? THD/IMD vs. frequency? Then try it! You do not need an AP2 for it. IMHO it is easier to believe, what you can see on the paper. And it is easier to establish congruent measuring setups too, a blind A/B-comparison is much more complicated.
Regards, Timo
is the difference of the before/after-sounds measurable? THD/IMD vs. frequency? Then try it! You do not need an AP2 for it. IMHO it is easier to believe, what you can see on the paper. And it is easier to establish congruent measuring setups too, a blind A/B-comparison is much more complicated.
Regards, Timo
I agree with you about the transformer, but the difference in cost for the extra 500VA was only about $40 per transformer, and I figured this way it should be more than enough for any other project I'm likely to do in the future, and I knew it wouldn't be the limiting factor in the amp.classd4sure said:
For me, the -3db point is not good enough. I can hear the difference in two signals 1db to 1.5db apart, so I'm willing to do what I can to get the returns to the -1db point or less if possible.
The stock LC Audio Predator power supply has 20,000uf on it, and it just sounded plain bad to me. Adding another 20,000uf helped a bit, but when I paralleled two of the 82,000uf capacitors, it sounded a lot better, although still only ok, not good. But that's why I want to try the smaller capacitors with the home made PSU, to see if there's an optimum amount of capacitance.
tiki said:
Sorry, I don't have a scope, just a DMM.
As for comparison testing, all I'm using or really care about is my ears, since I'm the one who's going to be listening to it. But I'm pretty fussy and I do want the reproduction to be as realistic as possible. I find a blind A/B comparison to be not very effective when evaluating components in my system. Assuming that the component is of a quality close to what I find acceptable, I usually like to live with it for a few days seeing how it sounds with a variety of music and movies, then switch back to my standard system whose pluses and minuses I'm very familiar with. If it's really close, I might switch back and forth a couple of times, but usually I know what I like after the first multi-day trial.
I know this is all subjective and we all have different preferences, but it's all I have to offer.
Sounds great to me, not my intention to give you a hard time.
I like that you're experimenting and providing results! I just hope it doesn't become a standard that one requires a 2000000VA transformer to get a decent, 10W amp, a la class A, that'd be rediculous!
In your place I would have gone the same way... what's an extra 40$ for 500VA right? Seems crazy not to... I believe we suffer a like illness.
Such a transformer might help offset the size of the capacitors as well (with respect to the power factor). But then again...
"328,000uf of capacitors with bridge rectifiers and some bypass capacitors. With this combination, the amp was finally a contender; separation was excellent (as you would expect), the impact, dynamics, and control were outstanding and superior to the Threshold. The sound is very clean with excellent clarity and a great soundstage, but the highs still seem a bit rolled off; there's not the same airy spaciousness to the sound I get with the Threshold. Also, at medium to high volume levels the midrange gets a recessed sound, almost like it's at the end of a long tube, kind of a weird effect that is hard to describe."
WOW, that's no small amount. So you notice power dropping off at medium to high power levels.... with a tank of a supply like that??? Hmmmmm... Maybe this is the power factor thing creeping up on you. Once it starts to draw it's all reactive(current first .... voltage second... 90 degrees out of phase.. real power =zero...
That's worst case, but you see how it can be a problem. Maybe you can look forward to that going away when you use small caps (please let us know).
I also noticed you used the copper ground bar method as well as a plain star point.... which technique served you better?
Anyway, I really like what you did for a case Seems big enough to house everything easily, and you put the money into what really matters, well done.
I like that you're experimenting and providing results! I just hope it doesn't become a standard that one requires a 2000000VA transformer to get a decent, 10W amp, a la class A, that'd be rediculous!
In your place I would have gone the same way... what's an extra 40$ for 500VA right? Seems crazy not to... I believe we suffer a like illness.
Such a transformer might help offset the size of the capacitors as well (with respect to the power factor). But then again...
"328,000uf of capacitors with bridge rectifiers and some bypass capacitors. With this combination, the amp was finally a contender; separation was excellent (as you would expect), the impact, dynamics, and control were outstanding and superior to the Threshold. The sound is very clean with excellent clarity and a great soundstage, but the highs still seem a bit rolled off; there's not the same airy spaciousness to the sound I get with the Threshold. Also, at medium to high volume levels the midrange gets a recessed sound, almost like it's at the end of a long tube, kind of a weird effect that is hard to describe."
WOW, that's no small amount. So you notice power dropping off at medium to high power levels.... with a tank of a supply like that??? Hmmmmm... Maybe this is the power factor thing creeping up on you. Once it starts to draw it's all reactive(current first .... voltage second... 90 degrees out of phase.. real power =zero...
That's worst case, but you see how it can be a problem. Maybe you can look forward to that going away when you use small caps (please let us know).
I also noticed you used the copper ground bar method as well as a plain star point.... which technique served you better?
Anyway, I really like what you did for a case
Seems big enough to house everything easily, and you put the money into what really matters, well done.classd4sure said:WOW, that's no small amount. So you notice power dropping off at medium to high power levels.... with a tank of a supply like that??? Hmmmmm... Maybe this is the power factor thing creeping up on you. Once it starts to draw it's all reactive(current first .... voltage second... 90 degrees out of phase.. real power =zero...
That's worst case, but you see how it can be a problem. Maybe you can look forward to that going away when you use small caps (please let us know).
I also noticed you used the copper ground bar method as well as a plain star point.... which technique served you better?
Anyway, I really like what you did for a case
I'm just a hobbyist, a few EE courses a VERY long time ago, but I don't understand how power factor would be an issue for the DC supply. Can you explain or refer me to something where I can read up on it?
In any case I plan on trying different amounts of capacitance since I've read so many different opinions on diyaudio in both directions. I figure the best thing to do is to just try it, and see what I like, although I would actually prefer it if the best version is able to be made physically smaller. I just started out with the biggest parts first since I knew they would be the most difficult to fit in. Swapping them out for smaller parts later will be no problem.
I only used a plain star point. Ericpeters amp is the one with the copper bus bars. Personally, I think either approach should be fine as long as you connect everything to one grounding point on the bus bars. I did the wires primarily so that it would be easier to swap different capacitors in and out. For a final version, I think I'd probably go to bus bars for ease of assembly and looks.
The case has actually worked out great for putting the amp together: easy to modify, adequate space, no apparent performance compromise, and easy access for getting to and working on all of the parts. For a final version of the amp, I'd like something that looks nicer, but for experimentation, and for anyone who doesn't care too much about the looks, I'd highly recommend it. Besides, it's funny to have what looks like a couple of computers on the floor functioning as amplifiers.
The tower of power!
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Hi Greg,
I only have the small caps to bypas the diodes I don't have them on the main rails, never tried it without them. A friend of mine had the same model with lower transformer voltage and normal square bridge rectifiers without caps and this sounded also very good. (He is running Scintilla's in 4ohm, he now has a KSA100 and runs them in .5 ohm setting, he didn't want to risk bypassing the short circuit protection in the modules))
I've got the zap amps on Duetta Signatures, another interesting thing with the Zap monos is that the D-sigs appear to have added another octave on bottom end.
I've got my B&O Ice module stereo amp on a pair of Graz KLM ribbon restored Calipers in my home office. This works well for the purpose but is no contest for the zap's
You can sell me your Diva's, there is no better room than mine to put Diva's I can pick them up myself. I have to be in Southern California anyway next week. The calipers will fit everywhere. ALtough I'm not sure if the airline will accept diva's as hand luggage.
The zero distortion link is the one I meanth (Designing your own power supply). I followed their calculation regarding the leak-resistor sizing and estimated 10watt would be OK, but I found only these at my local supliier.
I've had discussions with LC-audio regarding the required size of Caps and transformer as well, but listening proved them wrong (or maybe lesser standards)
In my experience size of transformer (= low output impedance of the PS) is most important. And the quality of the of Capacitors.
My theory is that the high efficiency of the modules is the main reason for this: the current they draw from the ps will fluctuate almost linear with the music levels, this will result in an unstable spply voltage if your transformer has not got enough guts. (anyway it is just a theory)
I only have the small caps to bypas the diodes I don't have them on the main rails, never tried it without them. A friend of mine had the same model with lower transformer voltage and normal square bridge rectifiers without caps and this sounded also very good. (He is running Scintilla's in 4ohm, he now has a KSA100 and runs them in .5 ohm setting, he didn't want to risk bypassing the short circuit protection in the modules))
I've got the zap amps on Duetta Signatures, another interesting thing with the Zap monos is that the D-sigs appear to have added another octave on bottom end.
I've got my B&O Ice module stereo amp on a pair of Graz KLM ribbon restored Calipers in my home office. This works well for the purpose but is no contest for the zap's
You can sell me your Diva's, there is no better room than mine to put Diva's I can pick them up myself. I have to be in Southern California anyway next week.
The calipers will fit everywhere. ALtough I'm not sure if the airline will accept diva's as hand luggage.The zero distortion link is the one I meanth (Designing your own power supply). I followed their calculation regarding the leak-resistor sizing and estimated 10watt would be OK, but I found only these at my local supliier.
I've had discussions with LC-audio regarding the required size of Caps and transformer as well, but listening proved them wrong (or maybe lesser standards)
In my experience size of transformer (= low output impedance of the PS) is most important. And the quality of the of Capacitors.
My theory is that the high efficiency of the modules is the main reason for this: the current they draw from the ps will fluctuate almost linear with the music levels, this will result in an unstable spply voltage if your transformer has not got enough guts. (anyway it is just a theory)
classd4sure said:
One additional note, I wouldn't say that the power seemed to be dropping off, unless it was just at certain frequencies. The bass in all cases was very impressive, and some music played loud sounded great. It's kind of hard to describe what I was hearing, having never heard anything quite like it before. Also, the lack of airiness, or space, to the sound bothered me at least as much.
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