Mike2 said:
Thanks, good to know that they sound good 🙂 they measure also good.
t. said:
I bought them at mouser.com.
To answer Chris's question. One is mounted on the top of the PCB and the other on the bottom. The one on top fits very nicely in the position of the original cap.
Best regards
Gertjan
ghemink said:
What one for sure not should do is putting additional polyprop caps over the FC caps, this gives you a nice oscilating waveform due to the parasitic inductance of that FC cap and the polyprop (330nF WIMA) forming a high Q LC filter/resonator. This could be killed likely with a snubber, but that makes things just complicated. The polyprops also do nothing to reduce the spikes, so no benefit.
Attachments
Sorry for the late reply, Chris: 
So, it is good to change the bootstrap cap but not the "black ones" that accompany the MOSFETs to avoid getting oscilations?
I'll give them a try.
Sorry guys for the basic questions
Good luck with your mods to all!
M
I think I'll make DC couple better with my new active crossover.
Well, I allways get confused here.
So, it is good to change the bootstrap cap but not the "black ones" that accompany the MOSFETs to avoid getting oscilations?
OK, but why you allways try polypropylene caps here? Isn't there other options?
That, I knew 😀 I think we are stuck to Panasonic FC 470uF/100V.
I'll give them a try.
Yeah, I also want to try this on UCD400 because it seems easier than on UCD180. Simple 317/337 PS.
Sorry guys for the basic questions
Good luck with your mods to all!
M
I tried the Evox SMR 0.68uf yesterday for the output filter, I personally prefer these over the Auricaps already, they are not bad caps and work better for me than the standard yellow polyester.
I'm really struggling to find anything else to try which I can buy locally so if theres any UK UCD owners who know of anything worth trying😉
I also tried the Rubycon YXF 470uf 63v for the decoupling, these made a very big difference, the sound is much brighter, I'll leave them in for a while to see if that top calms down, if not its back to the brown chemicons😀
I've got some 680uf Panasonic to to try too
I'm really struggling to find anything else to try which I can buy locally so if theres any UK UCD owners who know of anything worth trying😉
I also tried the Rubycon YXF 470uf 63v for the decoupling, these made a very big difference, the sound is much brighter, I'll leave them in for a while to see if that top calms down, if not its back to the brown chemicons😀
I've got some 680uf Panasonic to to try too
Hi t. 🙂
Sorry to hear about the Rubycon's YXF. They have relativelly high ESR, if I recall well.
About PS decoupling I have a few questions:
*what if I try a lower capacitance Black Gate (I know you're not fond of them), around 100uF? From the noise point of view.
*has anybody tried Capxon capacitors? or know where to get them?
I'm beginning to study the specs and they are an option, if one can find them.
My CDPRO's PS has them and they seem to work OK.
http://www.capxon.com.tw/index3.htm
Cheers.
M.
Sorry to hear about the Rubycon's YXF. They have relativelly high ESR, if I recall well.
About PS decoupling I have a few questions:
*what if I try a lower capacitance Black Gate (I know you're not fond of them), around 100uF? From the noise point of view.
*has anybody tried Capxon capacitors? or know where to get them?
I'm beginning to study the specs and they are an option, if one can find them.
My CDPRO's PS has them and they seem to work OK.
http://www.capxon.com.tw/index3.htm
Cheers.
M.
maxlorenz said:
Hi Mauricio,
Well the YXF are new so they may improve after some burning in, they currently have a metallic top end and are rather forward sounding.
I will not be using the Panasonic FC again, I do not like these at all.
Actually I don't dislike BG's, infact I've not found anything to touch them (N types) in some circuits especially in parts of my dac or cathode bypass in my tube amp but in other applications they can sound shite so its best to experiment🙂
The main downside with these is the long burn in period.
I'd say 100uf would be too low for the UCD's and may sound too thin although I could be wrong😉
I'm afraid I've not tried the Capxon, I'll check them out, thanks for the link
ATB!
Leo
If it helps, I bothered to bring a scope home to look at the supply rails. With the stock caps, theres lots of high frequency spikes.
I wish I'd written down the amounts, but I wanna say it was several hundred mV.
That said, whatever it was, I recall my conclusion, you most definitely want low ESR, although I could be wrong from a sound stantpoint, but from a switcher standpoint, I wouldn' want to increase it any.
What was interesting was that the main supply rails (Ucd400, 59V rails, 15000uF bypass) didn't budge more than a volt even at clipping (music input), and at any listening level I"d really use, they didn't budge more than 100mV, including supply ripple.
Are the BG's low ESR?
I also assume your talking black gates, right?
Thanks
Mike
I wish I'd written down the amounts, but I wanna say it was several hundred mV.
That said, whatever it was, I recall my conclusion, you most definitely want low ESR, although I could be wrong from a sound stantpoint, but from a switcher standpoint, I wouldn' want to increase it any.
What was interesting was that the main supply rails (Ucd400, 59V rails, 15000uF bypass) didn't budge more than a volt even at clipping (music input), and at any listening level I"d really use, they didn't budge more than 100mV, including supply ripple.
Are the BG's low ESR?
I also assume your talking black gates, right?
Thanks
Mike
Regulation!
Mike,
Just some points that need to be cleared up, this is with a basic torid fed supply, right? You were using a resistor type load on the amp of what value? There is no electronic regulation involved? What power rating does the transformer have? And finally, what brand is the transformer. All these questions are because I would expect voltage sag from the line power falling when loaded alone to exceed this value. Even with electronic regulation this is an impressive accuracy!
If you are measuring with no load on the amp the power supply/power line load is uniform whether there is an audio signal or not and the noise you are seeing is due to switching currents only. This is only a part of the story and not the most important at that. You do need to be delivering power to a load to know what is really going on.
Roger
Mike,
Just some points that need to be cleared up, this is with a basic torid fed supply, right? You were using a resistor type load on the amp of what value? There is no electronic regulation involved? What power rating does the transformer have? And finally, what brand is the transformer. All these questions are because I would expect voltage sag from the line power falling when loaded alone to exceed this value. Even with electronic regulation this is an impressive accuracy!
If you are measuring with no load on the amp the power supply/power line load is uniform whether there is an audio signal or not and the noise you are seeing is due to switching currents only. This is only a part of the story and not the most important at that. You do need to be delivering power to a load to know what is really going on.
Roger
Re: Regulation!
t,
The supply is a toroid, ~430VA I think, but don't know for sure as its from an old hk mono block I had, it says 430VA max input on the back of the chassis. Its from a harmon kardon hk775 monoblock. I recommend them for UcD400's 🙂 The toriod is pottend and canned in a steel can. No hum at all, electical or acoustic.
The load were my JBL 4435's, ~4-8ohms, mostly 8 ohms. Not scientific, just screwing around. Lets just say it was REAL LOUD at times. I'd say its was a pretty typical worst case real world test. Athough , hip hop, with the booming low end would see more pumping, but I can't imagine it being more than a three volts. Voltage rails pretty much stayed between 59V and 60V with pop music that did have good bass content and occational clipping. I might have seen an occational 59~61V due to pumping.
The input was music, there is no electronic regulation. Straight up single stock bridge, stock 15000uF 71V caps.......
I think part of the explaination is that its class D. That is, compared to linear amps, it just draws less current. For example, a linear amp delivering 5Amps into 8ohms draws 5A from the supply. A class D, draws far less, and that supply pumping everyone complains about is actually not all that bad, when the current is being sucked from one supply, its giving some back to the other supply. Bottom line is where the A/B is drawing say 5A, the class D draws only a fraction, depending on the supplies.
Its also worth pointing out that there is a serious advantage in class D to run the rails as high as you can, since the energy is 1/2 C*V^2 and the current out is really energy out for a class D vs linear.
I'll soon drag these into the lab and do some real measurements with an audio precison and some resistive loads and post scope plots....
The noisiest part of the supply is on the UcD board, as would be expected. Those 6 ferrites on the UcD really do filter out the hash from getting back to the supply.
I was all set to try FC's, but now I'm wondering if its worth it given some of the bad comments for them. I do feel they lack solid bass, althogh it is musical.
Regards,
Mike
p.s. The local stepdown transformer for my house is only about 50ft from my breaker box, and the wire run I'd guess is another 20ft, so maybe I'm luckly on line reg. Solid 120VAC.
sx881663 said:
t,
The supply is a toroid, ~430VA I think, but don't know for sure as its from an old hk mono block I had, it says 430VA max input on the back of the chassis. Its from a harmon kardon hk775 monoblock. I recommend them for UcD400's 🙂 The toriod is pottend and canned in a steel can. No hum at all, electical or acoustic.
The load were my JBL 4435's, ~4-8ohms, mostly 8 ohms. Not scientific, just screwing around. Lets just say it was REAL LOUD at times. I'd say its was a pretty typical worst case real world test. Athough , hip hop, with the booming low end would see more pumping, but I can't imagine it being more than a three volts. Voltage rails pretty much stayed between 59V and 60V with pop music that did have good bass content and occational clipping. I might have seen an occational 59~61V due to pumping.
The input was music, there is no electronic regulation. Straight up single stock bridge, stock 15000uF 71V caps.......
I think part of the explaination is that its class D. That is, compared to linear amps, it just draws less current. For example, a linear amp delivering 5Amps into 8ohms draws 5A from the supply. A class D, draws far less, and that supply pumping everyone complains about is actually not all that bad, when the current is being sucked from one supply, its giving some back to the other supply. Bottom line is where the A/B is drawing say 5A, the class D draws only a fraction, depending on the supplies.
Its also worth pointing out that there is a serious advantage in class D to run the rails as high as you can, since the energy is 1/2 C*V^2 and the current out is really energy out for a class D vs linear.
I'll soon drag these into the lab and do some real measurements with an audio precison and some resistive loads and post scope plots....
The noisiest part of the supply is on the UcD board, as would be expected. Those 6 ferrites on the UcD really do filter out the hash from getting back to the supply.
I was all set to try FC's, but now I'm wondering if its worth it given some of the bad comments for them. I do feel they lack solid bass, althogh it is musical.
Regards,
Mike
p.s. The local stepdown transformer for my house is only about 50ft from my breaker box, and the wire run I'd guess is another 20ft, so maybe I'm luckly on line reg. Solid 120VAC.
Well it may be worth trying the FC's Mike if you can source them cheaply and easily.
Personally I don't like their signature, I found things like piano loses the realism sounding more electronic, it actually reminds me of the classA amp I once built and to be honest with the UCD's I wanted to avoid that🙂
I've not had chance to look at my 180's on a scope yet, each of my modules has its own 600vA Holden and Fisher torroidal
It amazes me what affect the caps have on the sound, I would like to try some different psu caps next when I've enough cash, I'm still using 2 x 6800uf Aerovox ALP20 on each + and - rail with no bypass caps
Personally I don't like their signature, I found things like piano loses the realism sounding more electronic, it actually reminds me of the classA amp I once built and to be honest with the UCD's I wanted to avoid that🙂
I've not had chance to look at my 180's on a scope yet, each of my modules has its own 600vA Holden and Fisher torroidal
It amazes me what affect the caps have on the sound, I would like to try some different psu caps next when I've enough cash, I'm still using 2 x 6800uf Aerovox ALP20 on each + and - rail with no bypass caps
Cap question
T,
I think you are right to use no bypass on the bulk storage caps. This is due to the fact that a lot of the HF switching currents are not smoothed out on the amp board where they should be but are passed on to the big caps as HF pulses. This means that if you bypass the big caps with small ones you have formed a resonate circuit with the power wiring and this will cause ringing on the lines. This can be gotten around by doing snubbers but I have to wonder if it is worth the effort. Much better to kill it at the source and this requires a very low ESR filter on the amp board. It may also require a proper snubber on the board to be truly effective.
As we are finding out there is a lot to be learned in supplying clean power to a high power, HF switching circuit. Basically what we need is super low ESR across a very wide bandwidth. This will require multiple values with widely spread self resonate frequencies. It will also require snubberizing because of the PCB trace inductance. Considering what frequencies are represented by the switching waveforms even a couple of nH of inductance can be problematic. This is why expert PCB layout is so important.
Roger
T,
I think you are right to use no bypass on the bulk storage caps. This is due to the fact that a lot of the HF switching currents are not smoothed out on the amp board where they should be but are passed on to the big caps as HF pulses. This means that if you bypass the big caps with small ones you have formed a resonate circuit with the power wiring and this will cause ringing on the lines. This can be gotten around by doing snubbers but I have to wonder if it is worth the effort. Much better to kill it at the source and this requires a very low ESR filter on the amp board. It may also require a proper snubber on the board to be truly effective.
As we are finding out there is a lot to be learned in supplying clean power to a high power, HF switching circuit. Basically what we need is super low ESR across a very wide bandwidth. This will require multiple values with widely spread self resonate frequencies. It will also require snubberizing because of the PCB trace inductance. Considering what frequencies are represented by the switching waveforms even a couple of nH of inductance can be problematic. This is why expert PCB layout is so important.
Roger
Re: Cap question
Thank you Roger🙂
I've never liked bypassing caps when tried with other amps anyway to be honest, it always smeared the sound to my ears so I'll stick with your advice and won't bother.
I'd like to try some better psu caps but theres so many different types out there, I don't think my ALP20 are that great, I also use them in pairs on each rail (4 for each UCD module), maybe that is a bad idea?
sx881663 said:
Thank you Roger🙂
I've never liked bypassing caps when tried with other amps anyway to be honest, it always smeared the sound to my ears so I'll stick with your advice and won't bother.
I'd like to try some better psu caps but theres so many different types out there, I don't think my ALP20 are that great, I also use them in pairs on each rail (4 for each UCD module), maybe that is a bad idea?
Hi all:
I confess I've never read a BG chart!
While I'm here bored, thinking about PS decoupling caps, I wonder how ELNA (cerafine or silmic II) will behave here. Some find the silmic horrible. Other state that they confer a colorful and warm tone, with soft HF and good weight and roundness on lower frequencies. I can use a little of self indulgence.
From what I've heard with Elna starget I think the sonic description may be accurate: colorful and warm, with nice instrumental timbre.
Not very "transparent" maybe. ..or maybe I'm depressed by my HF noise.
Ah! I forgot, only 63V for 470uF.
Dear Mike:
Your email option is dissabled, dear
Kind regards.
Mauricio
Isn't it the mains PS cap task? I mean 10 to 15 thousand uF v/s 470uF. Sorry for my ineptitude.
I confess I've never read a BG chart! While I'm here bored, thinking about PS decoupling caps, I wonder how ELNA (cerafine or silmic II) will behave here. Some find the silmic horrible. Other state that they confer a colorful and warm tone, with soft HF and good weight and roundness on lower frequencies. I can use a little of self indulgence.
From what I've heard with Elna starget I think the sonic description may be accurate: colorful and warm, with nice instrumental timbre.
Not very "transparent" maybe. ..or maybe I'm depressed by my HF noise.
Ah! I forgot, only 63V for 470uF.
Dear Mike:
Your email option is dissabled, dear
Kind regards.
Mauricio
Hi Mauricio,
Well those 470uf's caps are a fair distance away from the main psu caps😉 think of all that added wiring and pcb track
BTW
Silmics
these have to be the worst caps I've ever tried, unless your system suffers from harshness etc avoid those things, this is only my opinion of course😉 Infact theres not many audiograde caps I do like, thats probably the main reason I'm trying out good but industrial type caps
ATB!
Well those 470uf's caps are a fair distance away from the main psu caps😉 think of all that added wiring and pcb track
BTW
Silmics
these have to be the worst caps I've ever tried, unless your system suffers from harshness etc avoid those things, this is only my opinion of course😉 Infact theres not many audiograde caps I do like, thats probably the main reason I'm trying out good but industrial type capsATB!
Portlandmike said:
Yes, the BGs are very low ESR, I plan to try the 100uF 100V BGs, maybe two in parallel to bring it to 200uF. The 220uF BGs are very expensive.
Bets regards
Gertjan
Hi Gertjan:
IF you try two 100uF/100V, BG-N type in parallel, PLEASE, bind them in antiparallel arangement and look its behaviour on scope
just use wide copper lead to join them, as per BG's recommendation.
(I would do this myself but lack equipment and expertise to do it )
Thanks in advance 🙂
M.
IF you try two 100uF/100V, BG-N type in parallel, PLEASE, bind them in antiparallel arangement and look its behaviour on scope
just use wide copper lead to join them, as per BG's recommendation.
(I would do this myself but lack equipment and expertise to do it
)Thanks in advance 🙂
M.
maxlorenz said:Hi Gertjan:
IF you try two 100uF/100V, BG-N type in parallel, PLEASE, bind them in antiparallel arangement and look its behaviour on scope
just use wide copper lead to join them, as per BG's recommendation.
(I would do this myself but lack equipment and expertise to do it
Thanks in advance 🙂
M.
What do you mean? Antiparallel? Then you need the N-types. The ones I have are polarized caps. I was thinking of mounting one at the top of the PCB and the other at the bottom (similar as I did with the 2x330nF WIMA output caps. This will keep the wiring short and thus parasitic inductance will be limited.
Thanks and best regards
Gertjan
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