Little Dot MK8SE / MK6 Super Mods (All verified mods are on first page)

Feb 13, 2022 at 2:41 PM Post #4,111 of 4,154
I ddn do it...๐Ÿ˜ฎ

Also, I forgot that I did extend my chassis a half inch(!) ๐Ÿ˜…


๐Ÿ™ƒ๐Ÿ™‚
Haha, who the hell did then? It looks even better than before :face_palm:.

Hey great to see that crazy amp again ๐Ÿ‘.

I don't think half an inch is enough for those Wimas ๐Ÿ™‚. My extension is 60mm and even then it's a tight squeeze for the 150uF cathode bypass Wimas which I just put in today.

I'll give it a week's burn in and comment on it then :).
 
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Feb 14, 2022 at 4:57 AM Post #4,112 of 4,154
SMLD MODS: (finished.. er.. sorry.. resumed.. temporarily..... finished.. again!)

1uF Mundorf SIO WCF caps, 150uF Wima cathode bypass caps

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The finished amp ๐Ÿค’๐Ÿฅด๐Ÿค•. Only just enough room for those Wimas, even with the chassis extension. That's the best position for them closest to the connections. Fortunately they are positioned right under the fans... I didn't plan that... so if they are a tad warm they should get ample cooling. (The cardboard is mounted on some silicone filler to meet up with the base when it is screwed on).

Nearly every square inch of the insides is taken up now!

Good feeling now that it is finished... well maybe some bling next, see if I can outdo Maxx with the LED flashing lights around the chassis... hmmmm.... ๐Ÿ˜…๐Ÿฅณ

You can follow my mods pages: 50, 53, 55, 57, 62, 65, 66, 68, 69, 70, 71, 72, 147, 179, 230, 231, 234, 253, 273 which include pics. Also Mogos mods are here; 33-38, and SonicTrance here: 23, 43, including some great pics.
 
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Feb 14, 2022 at 5:10 AM Post #4,113 of 4,154
@CopperFox I just checked the resistance of the meters while I was inside the amp, it is 0.4R in place.
 
Feb 20, 2022 at 4:29 PM Post #4,114 of 4,154
I've burned in the Wima film cathode bypass caps and my impression is that the film caps have a smoother sound, less dynamic than with the lytics I had before, not as much textural detail and a tad boring if I'm honest. I was a bit surprised because I thought that film caps would provide the most changes, more so than the WCF caps that I had just increased to 1uF recently, but the opposite is the case. With that change the difference was quite striking, more weight and body to the sound and therefore more dynamics and also a more pronounced soundstage with all that going on. So I've decided to change back to the lytics because I'm really missing the sound I got after the last change. I'm slightly surprised because I'm not that much of a bass head but I've missed that lively sound.

The film caps were 150uF and it's possible that 200uF would have made more of a difference but I don't think so going by the frequency curve from the cathode bypass calculator which is virtually identical for the 200uF. Maybe it might have affected the cutoff and let in more bass but I don't think so. I feel that this might be a characteristic of film caps that they have a flatter, more seamless sound.

The reason I wanted to try the film caps in that position was to see if the sub bass could be tightened up a bit with the increased speed and lower ESR but I couldn't really tell any difference.

The upshot of this is that maybe an extended chassis isn't necessary for top level sound so it might be preferable to save all that effort :sweat:๐Ÿฅด.

Edit: I also tried the dynamic test and as with the WCF caps this was the same as before, ie. there were still bass dips as shown on the meters so no increased power handling capability with the Wimas.
 
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Feb 20, 2022 at 4:33 PM Post #4,115 of 4,154
The Duelund JDMs did sound like I've read the Duelund CASTs' sound described so it seems they could be the same as the CASTs but with lower tolerance and different leadout as their Nordic distributor had said. Which makes the JDMs also quite good value. Their sound is still more refined and coherent from the Miflexes. They have more microdetail but to my ears slightly less dynamics than the Miflexes. The bass response is slightly calmer with slightly less impact but more focus on a controlled post-impact. I might need to test them further but I think I may prefer the Miflexes for their slighly rougher and slightly more impactful sound. Or maybe it's just that I've gotten very used to them :)

Yes I remembered you said something similar, (highlighted above). That is exactly how I felt about the Wimas!

Still you don't know until you try.

Edit: I will try the Shuguangs next while I have the Wima's in.
 
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Feb 20, 2022 at 5:54 PM Post #4,116 of 4,154
@CopperFox I just checked the resistance of the meters while I was inside the amp, it is 0.4R in place.

Now that I've measured the resistance of the vu meters I have, they are all slightly below 1R between 0,7R to 0,9R (stock and two kinds of replacements). So that doesn't seem to be the issue.

I've been also looking around the amp to see if there is anything that looks wrong - spent three hours on that today. Still on my latest attempt to boot the amp up there's no sound, only the left meter lights up and moves to about 10ma and the right side doesn't move.

I've burned in the Wima film cathode bypass caps and my impression is that the film caps have a smoother sound, less dynamic than with the lytics I had before, not as much textural detail and a tad boring if I'm honest. I was a bit surprised because I thought that film caps would provide the most changes, more so than the WCF caps that I had just increased to 1uF recently, but the opposite is the case. With that change the difference was quite striking, more weight and body to the sound and therefore more dynamics and also a more pronounced soundstage with all that going on. So I've decided to change back to the lytics because I'm really missing the sound I got after the last change. I'm slightly surprised because I'm not that much of a bass head but I've missed that lively sound.

The film caps were 150uF and it's possible that 200uF would have made more of a difference but I don't think so going by the frequency curve from the cathode bypass calculator which is virtually identical for the 200uF. Maybe it might have affected the cutoff and let in more bass but I don't think so. I feel that this might be a characteristic of film caps that they have a flatter, more seamless sound.

The reason I wanted to try the film caps in that position was to see if the sub bass could be tightened up a bit with the increased speed and lower ESR but I couldn't really tell any difference.

The upshot of this is that maybe an extended chassis isn't necessary for top level sound so it might be preferable to save all that effort :sweat:๐Ÿฅด.

Edit: I also tried the dynamic test and as with the WCF caps this was the same as before, ie. there were still bass dips as shown on the meters so no increased power handling capability with the Wimas.

For me the Wimas took about eight weeks to burn in, with treble detail and sharpness improving along the way.

The difference in bass to the Nichicons was also quite clear. The Nichicons in comparison had an elevated, higher-than-neutral midbass response/impact but were smeared below that - and also that edginess in the treble (I previously described those as "burst-like or jagged characted") . Which made me think they are designed to sound that way to be nice while masking the limitations that electrolytics have - The Wimas' sub-bass sounds more powerful and detailed but they don't highlight midbass in a similar fashion. With the Wimas the lowest sub-bass detail was no longer markedly worse than with my solid state amps.

There may be also some more tuning options to have some of those electrolytics' characteristics without the sub-bass deficit and other issues... (While trying different resistance values for the impedance mod, I once put 2,2k 5W Kiwame resistors in parallel with the 330R Mills MRA to get to 290R... and the sound with the parallel Kiwame resistors there was quite different and reminded me of the Nichicons. That was actually one thing I was going to experiment with next - putting various audio resistors in that position).

Yes I remembered you said something similar, (highlighted above). That is exactly how I felt about the Wimas!

Still you don't know until you try.

Edit: I will try the Shuguangs next while I have the Wima's in.

Hmm, my feeling of the Duelunds so far is that they sound like they are designed to make speakers sound pleasant and refined... which they are.

I'm afraid the 6N5PJs may still have that softness without the film psu output caps - at least for me the combination of film decoupling caps and film psu output caps was what made them sound good.

While not having a working MkVi I've done some mods to my iFi Pro iCan after seeing it had six Elna Silmics in the signal path. Well they are now Nichicon KZs and the tubes are now Tung-Sols. Actually ordered more of the 200uf 400v Wimas for it too. Unfortunately its case can't be extended without being completely mangled.
 
Feb 20, 2022 at 7:15 PM Post #4,117 of 4,154
Now that I've measured the resistance of the vu meters I have, they are all slightly below 1R between 0,7R to 0,9R (stock and two kinds of replacements). So that doesn't seem to be the issue.

I've been also looking around the amp to see if there is anything that looks wrong - spent three hours on that today. Still on my latest attempt to boot the amp up there's no sound, only the left meter lights up and moves to about 10ma and the right side doesn't move.
Don't think it is the meters, probably the same as mine if you measured them in situ in the amp.

You say you have looked around the amp, what have you done, have you tested all the connections you made for continuity, especially the recent ones you did. Just look at all the connections and test them along the trace on the board with neighbouring connections which should show continuity, if not that is the fault. I know for example that a bad connection I had was only revealed when I repositioned some parts inside the amp before closing it up. That had exposed a bad connection which had moved when I repositioned the parts. I suspect something similar with your amp, it was working fine up until recently?

Keep us informed, we'll try to help.
 
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Feb 20, 2022 at 7:24 PM Post #4,118 of 4,154
For me the Wimas took about eight weeks to burn in, with treble detail and sharpness improving along the way.
I could try burning them in a bit more, I've spent 100 hours though. How much did you do?
The difference in bass to the Nichicons was also quite clear. The Nichicons in comparison had an elevated, higher-than-neutral midbass response/impact but were smeared below that - and also that edginess in the treble (I previously described those as "burst-like or jagged characted") . Which made me think they are designed to sound that way to be nice while masking the limitations that electrolytics have - The Wimas' sub-bass sounds more powerful and detailed but they don't highlight midbass in a similar fashion. With the Wimas the lowest sub-bass detail was no longer markedly worse than with my solid state amps.
That is impressive, I think your PSU film caps might have helped overall. I don't intend to change mine. I don't think my HE-500's pick up a lot of sub bass anyway.

It's possible that film caps would be as good as you say, because of the feedback from members at the beginning of the thread, but they haven't worked for me so far, at least without going the full distance and changing PSU and uprating decoupling caps. But I really liked the dynamics of the uprated WCF caps and could easily overlook the slight sub bass deficit with my current headphones.
 
Feb 21, 2022 at 5:29 AM Post #4,119 of 4,154
For me the Wimas took about eight weeks to burn in, with treble detail and sharpness improving along the way.

The difference in bass to the Nichicons was also quite clear. The Nichicons in comparison had an elevated, higher-than-neutral midbass response/impact but were smeared below that - and also that edginess in the treble (I previously described those as "burst-like or jagged characted") . Which made me think they are designed to sound that way to be nice while masking the limitations that electrolytics have - The Wimas' sub-bass sounds more powerful and detailed but they don't highlight midbass in a similar fashion. With the Wimas the lowest sub-bass detail was no longer markedly worse than with my solid state amps.
Thinking about these Wimas I will give them a bit more burn in time and see what happens.

My feeling after that fantastic dynamic, rich tone I had before, after installing the uprated WCF Mundorf caps is that that is the sound I am happy with. If it's detail and sharpness then I have all the clarity with the CCS in place and don't really want too much sharpness in sound because I'm loving the tone from the new WCF caps now. So that is probably not the type of tone I want with the Wimas.

I agree with you about the sound with the Nichicons but could limit the elevated midbass with a slightly lower WCF value if that is what I want. And I can overlook the smearing of the subbass you mention because I don't hear that much with my headphones and I don't want too much subbass.

Speaking of that jagged treble sound I'm wondering if that could be lessened with non polar caps such as non polar Kaisei's, maybe. I'll think about whether to do that or reistall my Nichicons.

Finally I think that as you say in order to achieve the full advantages of the film caps it would be necessary to install the PSU caps as well, don't know if I want to go down that road though. And it all comes down to synergy. Your headphones are bassy I think and you like bass, whereas I don't like heavy bass, I prefer more of a balanced sound across the frequency band. So I think I may have hit on the right combination for me. I would certainly be happy with the higher value WCF caps and the overall sound as it is for good.
 
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Feb 21, 2022 at 9:56 AM Post #4,120 of 4,154
I could try burning them in a bit more, I've spent 100 hours though. How much did you do?

Hmm it's hard to say how much exactly but it must have been somewhere around 300 hours. I do remember that it was the treble in particular that would improve in sharpness, detail and variety over time. The burn-in took a longer time than for any other component I've installed so far.

Finally I think that as you say in order to achieve the full advantages of the film caps it would be necessary to install the PSU caps as well, don't know if I want to go down that road though. And it all comes down to synergy. Your headphones are bassy I think and you like bass, whereas I don't like heavy bass, I prefer more of a balanced sound across the frequency band. So I think I may have hit on the right combination for me. I would certainly be happy with the higher value WCF caps and the overall sound as it is for good.

My feeling about the Wimas is that they are both technically proficient with their ability in bass and treble detail - and that they are also quite neutral and I hardly ever call anything neutral. And I don't really believe that people actually want a neutral sound, but a sound that they like. The advantage of a component having a neutral sound, such as here with the cathode bypass caps, would be that they would allow the other components in the system to further show their character instead, such as tubes or resistors or wiring, other capacitors and so on.

So if the goal would be have a sound with some characteristics that the Nichicon KZs there would have, it may be achieved with choice of other components such as driver and power tubes, wires, resistors etc, without some of the deficiencies that the Nichicons may have. That's one reason I'd find the Wimas preferable.


PSU output caps in general are among the components that from what I've seen on various audio devices will have the greatest effect on amount of some forms of distortion.
 
Feb 21, 2022 at 10:31 AM Post #4,121 of 4,154
Hmm it's hard to say how much exactly but it must have been somewhere around 300 hours. I do remember that it was the treble in particular that would improve in sharpness, detail and variety over time. The burn-in took a longer time than for any other component I've installed so far.



My feeling about the Wimas is that they are both technically proficient with their ability in bass and treble detail - and that they are also quite neutral and I hardly ever call anything neutral. And I don't really believe that people actually want a neutral sound, but a sound that they like. The advantage of a component having a neutral sound, such as here with the cathode bypass caps, would be that they would allow the other components in the system to further show their character instead, such as tubes or resistors or wiring, other capacitors and so on.

So if the goal would be have a sound with some characteristics that the Nichicon KZs there would have, it may be achieved with choice of other components such as driver and power tubes, wires, resistors etc, without some of the deficiencies that the Nichicons may have. That's one reason I'd find the Wimas preferable.


PSU output caps in general are among the components that from what I've seen on various audio devices will have the greatest effect on amount of some forms of distortion.
Some good points there, I will persist a bit longer. Certainly so far the Wimas haven't really shown what I would have expected, treble not very clear and bass not improved over the lytics so far. Also being polypropylene, and especially being non polar I thought would give them a considerable advantage. So maybe as a dry construction unlike lytics that is the reason for the long burn in time.

If they do indeed allow the newly installed WCF caps to shine then it will be worth it. I had thought that the increased dynamics of the uprated WCF caps would pair nicely with cathode bypass film caps.

I have to say I do like the treble tone with the Nichicons and WCF Mundorfs atm before installing the Wimas, it is clear, extended and has a nice bite without being harsh. We shall see after some more burn in time what happens!

I looked at the Kaisei non polar but decided against trying, the 25v ones are around ยฃ11 but the price rises dramatically for anything over that, as I like the Nichicons already I might stick with that.

I do already have adequate value decoupling caps and you are quite right that PSU demands a careful design which is why regulated power is so important, and that's why I've gone some distance toward that with the CCS. After installing that I did notice a cleaner sound, but I don't want to lose all of the tube.. some would say distorted.., sound. So even without the film PSU caps I think my system should be adequate as is.
 
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Feb 21, 2022 at 4:33 PM Post #4,122 of 4,154
Thinking about these Wimas I will give them a bit more burn in time and see what happens
Noooooo... garbage! ๐Ÿ˜…

I have to say I do like the treble tone with the Nichicons and WCF Mundorfs atm before installing the Wimas, it is clear, extended and has a nice bite without being harsh. We shall see after some more burn in time what happens!
The red wimas were never meant for audio path.
Yes they have good pulse ratings, for PSU, but never designed specifically for audio.
They are PSU caps, which you will see some cheapo companies use for audio path. Only the blue ones I ever saw used in expensive gear.

Sometimes you have to follow what the design intention is for. I would not use the red ones for audio, just for the PSU.
Of course I have read that they are nice and smooth..(flat!).
BUT, You won't get any more positive impressions than that. ๐Ÿฅฒ

So since we going for top sound, I will be using silver for WCF cap and some other nice electrolytics for supplement my cathode cap.
I already have the .1uf rifa "paper-in-oil" paralleled in there on top-side of board, for the highs, so that stays for me.
๐Ÿค‘๐Ÿ™‚

I've been also looking around the amp to see if there is anything that looks wrong - spent three hours on that today. Still on my latest attempt to boot the amp up there's no sound, only the left meter lights up and moves to about 10ma and the right side doesn't move
You need to check the wiring going to the meters, because as I recall, that wiring is made of a cheap, brittle metal, so I would make sure that the wiring connections from that right meter to the board are not open or shorted. Hope that helps.

PSU output caps in general are among the components that from what I've seen on various audio devices will have the greatest effect on amount of some forms of distortion
The PSU output caps here are large electrolytic which are then supplemented by the "decoupling" film caps by the output tube PSU area, so I feel this is already covered enough for me. ๐Ÿ‘
 
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Feb 21, 2022 at 6:37 PM Post #4,123 of 4,154
Noooooo... garbage! ๐Ÿ˜…
Hehe :face_palm: ๐Ÿ˜ญ.

I can't afford a V-Cap :rolling_eyes:.
Only the blue ones I ever saw used in expensive gear.
I think these are the very small wimas with low values AFAIK.

Of course I have read that they are nice and smooth..(flat!).
BUT, You won't get any more positive impressions than that. ๐Ÿฅฒ
Since I have gone down this path I want to see for myself so I'll give it the benefit of the doubt.

So since we going for top sound, I will be using silver for WCF cap and some other nice electrolytics for supplement my cathode cap.
I already have the .1uf rifa "paper-in-oil" paralleled in there on top-side of board, for the highs, so that stays for me.
๐Ÿค‘๐Ÿ™‚
That should be excellent. If you're going for Mundorfs they have the same construction as film caps - metallized polypropylene but the electrolytic is oil, so should be some qualities of both.

Hey what about those non polar Kaiseis for cathode bypass?
You need to check the wiring going to the meters, because as I recall, that wiring is made of a cheap, brittle metal, so I would make sure that the wiring connections from that right meter to the board are not open or shorted. Hope that helps.
I blew open one of my meters and it didn't make any difference to the amp the voltages were all good. I think he should check his connections first with a DIMM.
The PSU output caps here are large electrolytic which are then supplemented by the "decoupling" film caps by the output tube PSU area, so I feel this is already covered enough for me. ๐Ÿ‘
Yep, agreed ๐Ÿ‘. The PSU lytics have a huge capacity to meet the requirements on them. But I do think that for PSU those film Wimas would provide fast power to beef up the PSU also, so you pays your money and you takes your choice as they say.
 
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Feb 22, 2022 at 10:39 AM Post #4,124 of 4,154
Just been looking up opinions on Wimas, I haven't done this before. It seems this one quite likes it: https://www.enjoythemusic.com/diy/1108/capacitor3.htm

whereas this one doesn't think that much: https://www.humblehomemadehifi.com/Cap.html

so in view of the fairly low ratings I've decided to give mine one more weeks burn in and if no noticeable improvement I will jettison the idea. Anyway at least I've tried but I'm still thinking of that dynamic, lively sound I heard before with the uprated WCF caps, can't wait to go back to this. I think that will be it re: cap trials.

And I now have a pretty good impression of film caps, at least the ones which don't have to be brought in on a HGV ๐Ÿ™‚.

Edit: @CopperFox I was interested if you had done the dynamic test at full volume, if your Wima's are performing as would be expected, especially your PSU caps, then I would expect very little movement with the meters on bass dips, and this is one area I would expect the film caps to be superior to lytics. If so then we will know that the PSU is a good place to put those caps, as well as decoupling, even if opinion varies over the cathode bypass position.
 
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Feb 23, 2022 at 10:25 AM Post #4,125 of 4,154
Guys! I was just checking out those non polar Kaisei's and I came across this in someone's DIY build thread where he mentions putting in the Kaisei's after having no bypass caps in at all... "The difference is pretty BIG! With the cathodes bypassed, there is a collpase in the soundstage, instrument separation suffers, there is less definition in the bass, and the high end sounds more harsh. It isn't subtle whatsoever. The amp doesn't sound bad with the cathodes bypassed, but once you've heard them unbypassed, no way you could go back. Audio quality is all relative after all. I did do some FFT measurements, bypassing the cathode resistors doesn't seem to affect distortion in a measurable way."

I remember coin saying something similar way back in the thread.

Could this be the way to go I wonder?

Edit: OK, maybe not. Here's another quote "No bypass means higher output impedance (cathode resistor x mu + rp) which may or may not be an issue depending on the following stage. The reason gain is lower is because the unbypassed cathode resistor introduces degenerative feedback which like all feedback reduces gain, but also reduces stage distortion. Again this may or may not be an issue depending on the linearity of the gainstage been used. That is to say a linear triode with bypass will have lower or equal distortion than a unlinear gainstage with dengenerative feedback.

Its about the design and the choices which are appropriate to the design. As an example I would use a no bypassed input stage if the loading of the preceding stage was light - such as a cathode follower. This would give lower overall distortion at the cost of a slight loss of gain."


I believe it might work in conjuction with a CCS such as I have but don't know if it would be worth it.

BTW it looks as though there might be no difference between polar or non polar with small voltages of around 1 or 2v. As I remember the voltage drop over the cathode bypass is 10v so that is something that could be determined experimentally.
 
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