Sooo....
Coming back on the various tests we did. OK, these aren't blind tests, but well... nearly. I let all filters in their identical casings and brought amp, jumpers and filters to my friend Gilles without a word. he had no clue on what was done nor what to expect, except one filter had a knot to be identified. I said: Just try it over the coming days, take your time, compare with your Class D and Onkyo, and come back
I just gave hints about the different combos and way to plug them (jumpers and filters). I didn't change the bias. Nor have I yet tried the ACA Mini vs my own VFET. I wasn't there when he did his tests, I just had a quick listening at the begining - making sure all was right - and a few days later to enjoy the result. LS are Klipsch RP-8000F, very well suited to this amp. Source was high res through Eversolo Z8, quite decent DAC BTW.
First of all, whatever the filters and jumpers, the ACA Mini is a fabulous little amp! It is marvelous, not just cute, but really a non expensive amp that sounds great. Probably the best option vs Class D for beginners! An absolutely great addition!
Now to the results. I suspect jumper position is system related, but to our amazement, shame on us "distorders", jumpers out was this time prefered. Sounded for whatever reason more real, closer. Strangely, "in" sounded a tad more holographic, something normaly associated to H2 but well. Flattering but sounded for whatever reason less realistic, less homogeneous. So quite the opposite from what I would have expected as engineer, but Gilles is musician and has also good ears...
More important now, as anyone can play easily with the jumpers: to the filters.
I love MJ's SMPS filters and they never brought any negative results. I built over a dozen of them and always have 2 extra "ready to try".
Well, this time the result is more mitigated. Yes, one filter indeed cleaned the music message and brought more clarity and details. But it robbed some dynamics at Gilles according to him. Something I hadn't experienced so far, or experienced sometimes when daisy chaining 2 of them as I did for my own VFET before moving back (and back then Gilles was also there with me when I did all this). BTW, daisy chaining here didn't brought any improvement on that, but that could be expected at least probably.
So yes, the usual SMPS filter brings some positive despite the VG "oversized low ripple SMPS", but is overall not really a great addition here due to the pereived dynamic loss. So rather mitigated.
On the contrary, the simple Murata coil between the SMPS and ACA Mini sounded.... as the ACA Mini should have sounded IMHO. Just RIGHT. First off, it did a lot of cleaning, more than MJ's Filters. Secondly, it didn't rob any of the dynamics. Nor anything else. In short: it is a worthwhile non expensive addition without any negative (to our ears). You could build that filter in a small casing the way I did it and just plug it in and out for quick comparisons. Or just think on how to include it directly. IMHO, the ACA Mini kit from the store could greatly benefit from this additional part in the future - it costs just a couple of bucks and really sounds as if it was made for it.
Gilles tried daisy chaining MJ's filter and the Murata coil filter (credits go here to MJ aswell anyway!) and that brought no additional benefits... nor really any negative BTW. It is like the coil filter dominated the overall sonic signature and dynamic. We had only one coil, so we didn't try daisy chaining the "coilfilters", but given the expected results on the paper not sure it would bring more... but who knows?
At the end of the day Gilles loved the ACA Mini so much he is... likely to have one in a very short time. Or perhaps even 2 as they come cheap and it could be fun experimenting (various) biamping configurations.
The big SMPS we have allow us to expriment aswell in this area (one SMPS + 1 coil filter for 2 amps... or doubling it all) before finalising the end set up.
There is also one thing I wish one day to experiment: additional conventional filtering upstream (CLC) or even linear PS. In a perfect world at Gilles we would keep everything of the ACA Mini including its sonic signature (very close to my VFET on that point) but say with (even) more speed or slam, immediacy, without loss in fluidity though. That would then be a giant killer... well, it probably is anyway already with efficient LS!
Bottom line: try that Murata coil ASAP! Unless you like it very relaxed with the std SMPS filter, you are likely to be very surprised. Either way, once again with SMPS filtering is the way forward.
I hope this helps
Claude (and Gilles of course)
Coming back on the various tests we did. OK, these aren't blind tests, but well... nearly. I let all filters in their identical casings and brought amp, jumpers and filters to my friend Gilles without a word. he had no clue on what was done nor what to expect, except one filter had a knot to be identified. I said: Just try it over the coming days, take your time, compare with your Class D and Onkyo, and come back
I just gave hints about the different combos and way to plug them (jumpers and filters). I didn't change the bias. Nor have I yet tried the ACA Mini vs my own VFET. I wasn't there when he did his tests, I just had a quick listening at the begining - making sure all was right - and a few days later to enjoy the result. LS are Klipsch RP-8000F, very well suited to this amp. Source was high res through Eversolo Z8, quite decent DAC BTW.
First of all, whatever the filters and jumpers, the ACA Mini is a fabulous little amp! It is marvelous, not just cute, but really a non expensive amp that sounds great. Probably the best option vs Class D for beginners! An absolutely great addition!
Now to the results. I suspect jumper position is system related, but to our amazement, shame on us "distorders", jumpers out was this time prefered. Sounded for whatever reason more real, closer. Strangely, "in" sounded a tad more holographic, something normaly associated to H2 but well. Flattering but sounded for whatever reason less realistic, less homogeneous. So quite the opposite from what I would have expected as engineer, but Gilles is musician and has also good ears...
More important now, as anyone can play easily with the jumpers: to the filters.
I love MJ's SMPS filters and they never brought any negative results. I built over a dozen of them and always have 2 extra "ready to try".
Well, this time the result is more mitigated. Yes, one filter indeed cleaned the music message and brought more clarity and details. But it robbed some dynamics at Gilles according to him. Something I hadn't experienced so far, or experienced sometimes when daisy chaining 2 of them as I did for my own VFET before moving back (and back then Gilles was also there with me when I did all this). BTW, daisy chaining here didn't brought any improvement on that, but that could be expected at least probably.
So yes, the usual SMPS filter brings some positive despite the VG "oversized low ripple SMPS", but is overall not really a great addition here due to the pereived dynamic loss. So rather mitigated.
On the contrary, the simple Murata coil between the SMPS and ACA Mini sounded.... as the ACA Mini should have sounded IMHO. Just RIGHT. First off, it did a lot of cleaning, more than MJ's Filters. Secondly, it didn't rob any of the dynamics. Nor anything else. In short: it is a worthwhile non expensive addition without any negative (to our ears). You could build that filter in a small casing the way I did it and just plug it in and out for quick comparisons. Or just think on how to include it directly. IMHO, the ACA Mini kit from the store could greatly benefit from this additional part in the future - it costs just a couple of bucks and really sounds as if it was made for it.
Gilles tried daisy chaining MJ's filter and the Murata coil filter (credits go here to MJ aswell anyway!) and that brought no additional benefits... nor really any negative BTW. It is like the coil filter dominated the overall sonic signature and dynamic. We had only one coil, so we didn't try daisy chaining the "coilfilters", but given the expected results on the paper not sure it would bring more... but who knows?
At the end of the day Gilles loved the ACA Mini so much he is... likely to have one in a very short time. Or perhaps even 2 as they come cheap and it could be fun experimenting (various) biamping configurations.
The big SMPS we have allow us to expriment aswell in this area (one SMPS + 1 coil filter for 2 amps... or doubling it all) before finalising the end set up.
There is also one thing I wish one day to experiment: additional conventional filtering upstream (CLC) or even linear PS. In a perfect world at Gilles we would keep everything of the ACA Mini including its sonic signature (very close to my VFET on that point) but say with (even) more speed or slam, immediacy, without loss in fluidity though. That would then be a giant killer... well, it probably is anyway already with efficient LS!
Bottom line: try that Murata coil ASAP! Unless you like it very relaxed with the std SMPS filter, you are likely to be very surprised. Either way, once again with SMPS filtering is the way forward.
I hope this helps
Claude (and Gilles of course)
Claude,
I found MJ's AmyAlice filter to do a better job with the ACP+ and ACA Mini, over the PO89ZB filter.
Though I might have to give the Murata 1433428C a try.
I found MJ's AmyAlice filter to do a better job with the ACP+ and ACA Mini, over the PO89ZB filter.
Though I might have to give the Murata 1433428C a try.
If anybody is trying to put together an LTSPICE simulation, the unwanted but oh-so-very-real parasitics of the Murata inductor were stated in post #849:
However, you are on your own when seeking the oh-so-very-real parasitic values of the two "C5" electrolytic capacitors, one per channel. I don't know them.
_
However, you are on your own when seeking the oh-so-very-real parasitic values of the two "C5" electrolytic capacitors, one per channel. I don't know them.
_
