Yes, I thought about the polarity as soon as I turned it on and turned it off right away. I only even asked as I wasnt sure if the OPA pins had a true +/- on them. I know you cant put lytics in backwards or the pop their top....lol/
Yes, moving both the 10uf ceramic and .1uf C0G to the top is definitely something I will experiment with as well as dropping to 10uf lytics as soon as I get them in. You guys were 100% onto something though with the mix of size, type, and placement. It definitely improved the sound across the board. I would need to fully remove all the caps on the OPA to get back to a baseline sound though. The improvements are in dynamics and soundstage but this particular combo does feel "colored" to me, but it has ever since adding more than the .1uf C0G. Now its just a matter of playing with the combos, and of course trying all this with the 1656's once I get them in.
Im always happy to be proven wrong!
Yes, moving both the 10uf ceramic and .1uf C0G to the top is definitely something I will experiment with as well as dropping to 10uf lytics as soon as I get them in. You guys were 100% onto something though with the mix of size, type, and placement. It definitely improved the sound across the board. I would need to fully remove all the caps on the OPA to get back to a baseline sound though. The improvements are in dynamics and soundstage but this particular combo does feel "colored" to me, but it has ever since adding more than the .1uf C0G. Now its just a matter of playing with the combos, and of course trying all this with the 1656's once I get them in.
Im always happy to be proven wrong!
Addition... perhaps more important, not all OPAs are unity gain stable (admittely not the majority). That is an issue as for sure we aren't here going to run into gain bandwith issue/limitation with audio BW and very moderate gains of 2 and 1 - or so if I remember correctly the gains for each OPA's stage. I posted the values somewhere here...
The key here is that unity gain if confirmed here means NO stability for some OPAs.
Bottom line for all: stick to what works and is recommended, whatever that might be or whoever posts - far more touchy otherwise than pure sonic taste considerations if it blows the entire amp...
Claude
The key here is that unity gain if confirmed here means NO stability for some OPAs.
Bottom line for all: stick to what works and is recommended, whatever that might be or whoever posts - far more touchy otherwise than pure sonic taste considerations if it blows the entire amp...
Claude
Fortunately then Ive been very lucky as Ive tried a dozen OPA's and all worked fine, just the sound was different for all of them. I thought you came to the conclusion these were not unity gain though if I remember correctly. I believe you said there were 2 stages of gain added....pretty sure +2 & +1 were correct and the total gain was like 26db.
Well, if I said that then it must be right LOL!
Can't remember, has been months and moved on to other things, hence posting here for posterity, err OK, rather memory 🙂
However, if one stage's gain is 1, that means unity gain in one section / one sub OPA and that means defo only unity gain stable OPA or big potential probs... kind of probs such as you only notice too late as very HF oscillations and pop without any audible warning. Or whatever...
If total gain is 26dB, then given the amp chip's voltage gain of 20dB indeed that would leave 6dB gain for the entire pre amp section (=OPA stages) and that means my memory might have been Ok with one stage having a gain of 2 (=6dB) and the other of 1 (=0dB). It all adds up => only unity gain stable OPAs when rolling op amps in this unit please!
Can't remember, has been months and moved on to other things, hence posting here for posterity, err OK, rather memory 🙂
However, if one stage's gain is 1, that means unity gain in one section / one sub OPA and that means defo only unity gain stable OPA or big potential probs... kind of probs such as you only notice too late as very HF oscillations and pop without any audible warning. Or whatever...
If total gain is 26dB, then given the amp chip's voltage gain of 20dB indeed that would leave 6dB gain for the entire pre amp section (=OPA stages) and that means my memory might have been Ok with one stage having a gain of 2 (=6dB) and the other of 1 (=0dB). It all adds up => only unity gain stable OPAs when rolling op amps in this unit please!
Datasheets...
For older OPAs if it is not mentioned, then very likely they aren't unity gain stable!
For very modern OPAs, this gets tricky as some, inclusive TI on some recent OPAs, tend to omit to mention the unity gain stability, assuming that it tends to be the majority and now "saying nothing when stable" and only "warning if not"... to avoid disaster.
The OPA1656 datasheet hence said nothing and I had to ask its creator who confirmed indeed it was "of course unity gain stable".
Datasheet clears it in 99% of the cases and if the slight doubt then ask the manufacturer or on his forum (most have one).
For older OPAs if it is not mentioned, then very likely they aren't unity gain stable!
For very modern OPAs, this gets tricky as some, inclusive TI on some recent OPAs, tend to omit to mention the unity gain stability, assuming that it tends to be the majority and now "saying nothing when stable" and only "warning if not"... to avoid disaster.
The OPA1656 datasheet hence said nothing and I had to ask its creator who confirmed indeed it was "of course unity gain stable".
Datasheet clears it in 99% of the cases and if the slight doubt then ask the manufacturer or on his forum (most have one).
Ok, one last question for a bit if you please.......I know this was already partially answered of me but do you think Poly film (PP) caps would do a better job vs the C0G ceramics for bypassing? I can get PP caps that fit and are roughly the same price as the C0G ceramics. I know ceramic caps tend to "color" sound in a signal path but is this also true when were talking decoupling/bypassing? I feel like film would be better but Im not sure. Also, do you see any value in going slightly larger, say 0.22uf for bypass? Im still talking film or C0G.
Im also getting a couple different value Wima MKP 10 caps to try out on the OPA's as it sounds like they can ad real value there. I got (in cart, havent purchased yet) 0.1uf and 0.22uf to try, The question is, would these by in lieu of the 0.1uf C0G or on top of it? I assume I would also be keeping the 10uf lytic and 10uf X7R?
Thanks
Im also getting a couple different value Wima MKP 10 caps to try out on the OPA's as it sounds like they can ad real value there. I got (in cart, havent purchased yet) 0.1uf and 0.22uf to try, The question is, would these by in lieu of the 0.1uf C0G or on top of it? I assume I would also be keeping the 10uf lytic and 10uf X7R?
Thanks
Quote: "would Poly film (PP) caps would do a better job vs the C0G ceramics for bypassing?
=> I can't answer that one as I never compared them directly, only indirectly. In fact, I was very surprised to see how well a NP0/C0G cap performs as PS bypass cap. Good enough and better enough to make me think that it is damned close for our purpose to a PPP or ideal cap.
Now, that is all quite academic as I haven't seen any PPP cap that could fit in terms of size under the board. Glad to be proven wrong. Indeed you could fit them elwewhere but then it all makes only sense if the wiring is as short as possible... Or if you consider the OPA only.
Further, C0G is not a technology, but rather a norm which gives you a garantee regarding performance. You could probably have all kind of cap's tech, provided they deliver what C0G garantees. Now, to garantee that performance it takes nowadays a certain size (= form factor isn't great).
For other projects, where I don't bother about cost or space, I fit PPP as it is a known quantity. But from now on, for cheap projecst such as that one and of course for my SMD boards, I will defo consider C0G wherever I can. C0G as SMD is great because it can fit on top or between lytics legs and you don't have the usual cap legs that do matter (negatively) quite a lot to a cap performance at that level. I wonder how a MKS would fare vs a C0G but that would also depend on circuit (PS bypass is very different from say LS Xover LOL)
Quote: Also, do you see any value in going slightly larger, say 0.22uf for bypass? Im still talking film or C0G.
=> No problem at all, space permitting.
Quote: Im also getting a couple different value Wima MKP 10 caps to try out on the OPA's as it sounds like they can ad real value there.
=> Yep, I have 2 lying around I bought for this, on top of 8 MKS... they would fit nicely across the entire OPA board, was my initial intention 'worst case'. Note this 0.1uF are large but amongst the most reasonably sized PPPs.
As we had VG results with C0G and as we needed to *** 2 other caps and it got quite cramped there, we decided to leave it. On more high end project with more space I would have tried it, bought them initialy for that but I didn't expect us to have that much more benefits adding the other caps. Somewhere we had to draw a line...
Also, sadly, apart from the top of the OPA boards I see noway to replace the numerous (over 10) .1uF C0G caps that are under the board by Wimas. Not a cost issue (wouldn't make anymore sense at that stage indeed), but defo a space issue!
Quote: The question is, would these by in lieu of the 0.1uf C0G or on top of it? I assume I would also be keeping the 10uf lytic and 10uf X7R?
=> You need IMHO a baseline and make one change after the other. 1 by 1. And on this it s tricky if you only have one amp as you will have to rely on your auditive memory to evaluate the mod, and PPP caps need usualy some burn-in (eg time before their sound settles).
We had two otherwise identical units that we could switch on the fly, made it much easier for us.
Now, what I would do is keep the 10uF X7R and the 10uF lytic and just play to start with with the .1uF cap. You can swap the C0G with the PPP. I don't know the result, will be interesting. IMHO, and it is a guess based on the result and experience, but just a guess, I believe it can't harm the sound, but also believe that the C0G cap probably squeezed 90 to 100% of what was achievable by that kind of mod. In short, don't expect miracles. Wether it is worth the cost and hassle, you to tell us - for sure it will be a fun experiment.
Once done, and whereas I would only expect negative or neutral from that, you could still add the C0G on top to give it a listen. Shouldn't bring anything, but is not a dangerous mod re resonnance IMHO. Who knows, we were surprised to see X7R and lytic pairing well on that special occasion, unexpectadly.
Now to the process. If you don't want to waste endeless time, and if you decide to do all this for science and readers, you are probably better of doing it the reverse way as safer and easier. That is keeping your system as is with the C0G, add the PPP caps, listen to it... and then remove the C0G and listen. Then decide what you liked best (C0G as now, C0G+PPP cap, or just PPP cap). Of course during all this the X7R and lytic remain untouched.
What about this? 🙂
Claude
=> I can't answer that one as I never compared them directly, only indirectly. In fact, I was very surprised to see how well a NP0/C0G cap performs as PS bypass cap. Good enough and better enough to make me think that it is damned close for our purpose to a PPP or ideal cap.
Now, that is all quite academic as I haven't seen any PPP cap that could fit in terms of size under the board. Glad to be proven wrong. Indeed you could fit them elwewhere but then it all makes only sense if the wiring is as short as possible... Or if you consider the OPA only.
Further, C0G is not a technology, but rather a norm which gives you a garantee regarding performance. You could probably have all kind of cap's tech, provided they deliver what C0G garantees. Now, to garantee that performance it takes nowadays a certain size (= form factor isn't great).
For other projects, where I don't bother about cost or space, I fit PPP as it is a known quantity. But from now on, for cheap projecst such as that one and of course for my SMD boards, I will defo consider C0G wherever I can. C0G as SMD is great because it can fit on top or between lytics legs and you don't have the usual cap legs that do matter (negatively) quite a lot to a cap performance at that level. I wonder how a MKS would fare vs a C0G but that would also depend on circuit (PS bypass is very different from say LS Xover LOL)
Quote: Also, do you see any value in going slightly larger, say 0.22uf for bypass? Im still talking film or C0G.
=> No problem at all, space permitting.
Quote: Im also getting a couple different value Wima MKP 10 caps to try out on the OPA's as it sounds like they can ad real value there.
=> Yep, I have 2 lying around I bought for this, on top of 8 MKS... they would fit nicely across the entire OPA board, was my initial intention 'worst case'. Note this 0.1uF are large but amongst the most reasonably sized PPPs.
As we had VG results with C0G and as we needed to *** 2 other caps and it got quite cramped there, we decided to leave it. On more high end project with more space I would have tried it, bought them initialy for that but I didn't expect us to have that much more benefits adding the other caps. Somewhere we had to draw a line...
Also, sadly, apart from the top of the OPA boards I see noway to replace the numerous (over 10) .1uF C0G caps that are under the board by Wimas. Not a cost issue (wouldn't make anymore sense at that stage indeed), but defo a space issue!
Quote: The question is, would these by in lieu of the 0.1uf C0G or on top of it? I assume I would also be keeping the 10uf lytic and 10uf X7R?
=> You need IMHO a baseline and make one change after the other. 1 by 1. And on this it s tricky if you only have one amp as you will have to rely on your auditive memory to evaluate the mod, and PPP caps need usualy some burn-in (eg time before their sound settles).
We had two otherwise identical units that we could switch on the fly, made it much easier for us.
Now, what I would do is keep the 10uF X7R and the 10uF lytic and just play to start with with the .1uF cap. You can swap the C0G with the PPP. I don't know the result, will be interesting. IMHO, and it is a guess based on the result and experience, but just a guess, I believe it can't harm the sound, but also believe that the C0G cap probably squeezed 90 to 100% of what was achievable by that kind of mod. In short, don't expect miracles. Wether it is worth the cost and hassle, you to tell us - for sure it will be a fun experiment.
Once done, and whereas I would only expect negative or neutral from that, you could still add the C0G on top to give it a listen. Shouldn't bring anything, but is not a dangerous mod re resonnance IMHO. Who knows, we were surprised to see X7R and lytic pairing well on that special occasion, unexpectadly.
Now to the process. If you don't want to waste endeless time, and if you decide to do all this for science and readers, you are probably better of doing it the reverse way as safer and easier. That is keeping your system as is with the C0G, add the PPP caps, listen to it... and then remove the C0G and listen. Then decide what you liked best (C0G as now, C0G+PPP cap, or just PPP cap). Of course during all this the X7R and lytic remain untouched.
What about this? 🙂
Claude
Last edited:
a) They make PP (not sure what a PPP is) caps small enough to fit....
KEMET PPS .1uf KEMET SMR
Panasonic PP .1uf
Panasonic ECW
b) Yep, understood. I only refer to C0G to clarify the type of ceramic Im using. I know this is just a temperature rating and also determines the materials the capacitor is made of
c) That process sounds good and is likely what I will do. Ill have plenty of capacitor options now either way.....lol
Well, PPP stands for Polypropylene, and these are the one I like. Only these as a baseline.
There are other film caps, PPS etc., quite a lot of them in fact. I go for PPP, IMHO the best for our audio needs (exception migh be HF in DACs). Say I would want to put Wimas. I would look at MKPs. If I can't due to size/cost I may consider MKS, MKT... or C0G. But that's just me. I gave Wima just as an example because they have wonderfull papers that explain all the different film caps they manufacture and how to make your choice.
Now...The KEMETs you linked aren't PPP. They are MKS. I wouldn't bother! But that's me...
The Panasonic you linked... I like them very much. I you follow this thread you may have noticed this was one of our first mod, putting exactly them (other values of course) in the signal path at the entry. They are PPPs and excellent VFM, and still small for PPPs. They were recommended by Fab, as VFM signal path caps for his high end amps, says a lot. Can't fault them really for this amp, would love to evaluate them vs my recently beloved 940C, but time... argh...
Now, for the OPA PS Bypass, reading the specsheets, I decided nevertheless to prefer the WIMA MKP10. Again, FOR THAT APPLICATION. After ruling out all other contenders/options, I was left with these 2, but thought perhaps the WIMA could be a safer bet for PS applications than the Panasonics. Perhaps... well noting I also had a pair of Panasonics as back up LOL. Anyway, I went for the Wimas instead of the Panasonics, but can't say which is better. And... anyway (again LOL), given the result of the C0G cap, and the magnitude of the change, I didn't fit either. Say with C0Gs you have 90% of the achievable around this mod (I believe that from experience), and that's 2 points, what can you expect in a perfect world with a perfect cap? Perhaps 0.2 extra points if lucy... so lazy us we moved on to somethng else with more ROI in our view.
Have fun and let us know
Claude
There are other film caps, PPS etc., quite a lot of them in fact. I go for PPP, IMHO the best for our audio needs (exception migh be HF in DACs). Say I would want to put Wimas. I would look at MKPs. If I can't due to size/cost I may consider MKS, MKT... or C0G. But that's just me. I gave Wima just as an example because they have wonderfull papers that explain all the different film caps they manufacture and how to make your choice.
Now...The KEMETs you linked aren't PPP. They are MKS. I wouldn't bother! But that's me...
The Panasonic you linked... I like them very much. I you follow this thread you may have noticed this was one of our first mod, putting exactly them (other values of course) in the signal path at the entry. They are PPPs and excellent VFM, and still small for PPPs. They were recommended by Fab, as VFM signal path caps for his high end amps, says a lot. Can't fault them really for this amp, would love to evaluate them vs my recently beloved 940C, but time... argh...
Now, for the OPA PS Bypass, reading the specsheets, I decided nevertheless to prefer the WIMA MKP10. Again, FOR THAT APPLICATION. After ruling out all other contenders/options, I was left with these 2, but thought perhaps the WIMA could be a safer bet for PS applications than the Panasonics. Perhaps... well noting I also had a pair of Panasonics as back up LOL. Anyway, I went for the Wimas instead of the Panasonics, but can't say which is better. And... anyway (again LOL), given the result of the C0G cap, and the magnitude of the change, I didn't fit either. Say with C0Gs you have 90% of the achievable around this mod (I believe that from experience), and that's 2 points, what can you expect in a perfect world with a perfect cap? Perhaps 0.2 extra points if lucy... so lazy us we moved on to somethng else with more ROI in our view.
Have fun and let us know
Claude
So PPS <= C0G ceramics for this application? X7R>C0G>PPS>PPP?
And the TDK C0G's I got are basically the same size as the Panasonic PPP's. Not sure how Murata can make them so much smaller.
And the TDK C0G's I got are basically the same size as the Panasonic PPP's. Not sure how Murata can make them so much smaller.
Can't say exactly that.
And would rather be in the other direction ;-)
I would say from experience that on this amp (and often), for audio PS bypasses (except digital DAC's HF signals), regarding quality:
X7R < C0G < PPP
No clear line re PPS and C0G, depends so much on what part is used...
Regarding size, well, as we said C0G is just a spec, can throw a lot things in it as long as temp stable, ceramic, and other parameters that derivate mainly from these...
At the end, more than the size, it is the (absence of extra) sound we (usualy) want from these components...
Let us know your findings
Claude
And would rather be in the other direction ;-)
I would say from experience that on this amp (and often), for audio PS bypasses (except digital DAC's HF signals), regarding quality:
X7R < C0G < PPP
No clear line re PPS and C0G, depends so much on what part is used...
Regarding size, well, as we said C0G is just a spec, can throw a lot things in it as long as temp stable, ceramic, and other parameters that derivate mainly from these...
At the end, more than the size, it is the (absence of extra) sound we (usualy) want from these components...
Let us know your findings
Claude
Just got my 10uf Elna's in and swapped out the 22uf Nichicon I put on the top of the OPA yesterday. Elna's (or just the drop to 10uf) definitely sounds better. These are for sure the caps Ill use on the OPA's going forward. I will probably, though not today, swap out the 8+1 OPA DC filter caps to these as well.
Do you feel like there is any benefit in using a different/larger cap for that middle one?
Do you feel like there is any benefit in using a different/larger cap for that middle one?
Good, so the the 1st 10uF lytic is settled, the .1uF high quality cap is going to be... and the X7R 10uF is around ;-)
Middle cap... wouldn't think so. As long as bypassed should be OK, but haven't gone that route.
Middle cap... wouldn't think so. As long as bypassed should be OK, but haven't gone that route.
I know caps arent supposed to have a "sound" but I feel like Elna RFS caps are on the "warm" side but these are a long way from being broken in too.
OK, I tore my amp open, finally. Searched back in thread and started with the improvements. 1; bypass PS with the 2-2.2Uf and .1 uf caps. Tried it out, nice improvement with the 32V 3A wall wort. Then read on and started with bypassing the caps around the op amps. OOps, only bought 5 of the .1Uf caps-so just did the middle one. That is the one in the string of 5 in the middle (#3) from either end< right? then I did the opamp bypas but only with .1Uf and 10Uf ceramic caps. I didnt feal like trying to solder the other cap on top of/and to the legs of the 5532. Wow! what a sound improvement. My full range speakers disappeared. The sound didnt come from the speakers but was just out there in front of me!!! Amazing! Then I tried opamp switching. Magic was gone mostly? Does it take time for opamps to break in? I will go back in the thread and try and get a pair of the 1656 op amps to taste what it can do? I trust Claude"s taste buds!.
Claude- I am in same history boat so to speak-my father was a pro Jazz bassist all my life. I was his roady the last couple of years he was alive and know how it is supposed to sound! Havn,t messed with the meanwell power supply you linked yet. Was hoping for the beautiful filter yet to be revealed? so much thanks for all your help in improving this little amp.
Claude- I am in same history boat so to speak-my father was a pro Jazz bassist all my life. I was his roady the last couple of years he was alive and know how it is supposed to sound! Havn,t messed with the meanwell power supply you linked yet. Was hoping for the beautiful filter yet to be revealed? so much thanks for all your help in improving this little amp.
Thanks mate!
Great job and well done!
And yes, you got the right "middle cap".
Some OPAs do sound indeed a bit better after 10h or so IME, but it is say a 10% increase, so 90% of the sound is often there after a few minutes. Out of curiosity, what OPA did you fo for?
Thanks to you for reading my posts and carrying on the job
Claude
Great job and well done!
And yes, you got the right "middle cap".
Some OPAs do sound indeed a bit better after 10h or so IME, but it is say a 10% increase, so 90% of the sound is often there after a few minutes. Out of curiosity, what OPA did you fo for?
Thanks to you for reading my posts and carrying on the job
Claude
Sometimes for no apparent reason opamps don't get seated right or something. I would definitely try removing and reseating them before coming to a final conclusion. A guy I know had that happen to him and it made for a very closed in soundstage and vocals that sounded "far off" reseating them fixed it, for whatever reason. If you got the LM4562's and the other I recommended they should both sound much better than the 5532s that come with this.
Yes, they were the 2 you recommended ctfrommn. the first 1 came in a box and it had some awesome tight and grunty bass, but it didn;t have the trebble I look for. I think the powerful bass and mid bass hid the treble somewhat. I am trying the second a bit more. I have the amp open so I can change them out easy for ABing them. Its fun to experiment with all this. I think that amp "sound" is highly subjective. I want open, airy, and clean flat response, with wide soundstage and details. CAUTION: have significant other not in earshot of demo session! lol