Hi Franz,
Sorry if my wording was misleading... by "my suggestion" I wasn't of course refering to ME inventing anything, nor overestimating anything... I was merely worried that the supercap comments were perhaps somehow related to what "I" had posted here re tweaks for this Mini amp. Hence the "my" because I am still unsure if it has any connection or not, but wanted to rule any possible confusion out.
Bypasses can be fascinating, I am playing with them since several decades and inspiration on my side came probably from what Inifinity, a manufacturer I like quite a lot, did - although in their case a very different matter alltogether, but well - on its LS Xover in the late 70s... And even "they" probably borrowed the idea elsewhere. As for the explanation on how it works Z impedance reduction at HF is often given, and although true from an engineering POV I suspect there is probably more to it, especialy given the LF improvements. I liked quite the works published in the late 80s / early 90s by Jean Hiraga & Co in the Audiophile on that regard, whereas they are correct or not, who knows...
Last but not least, I don't know if someone ever suggested replacing or bypassing the supercap on the Mini, but thanks for confirming my thoughts that it wouldn't anyway do anything. I left it untouched of course as far as I am concerned.
Have a nice day
Claude
Sorry if my wording was misleading... by "my suggestion" I wasn't of course refering to ME inventing anything, nor overestimating anything... I was merely worried that the supercap comments were perhaps somehow related to what "I" had posted here re tweaks for this Mini amp. Hence the "my" because I am still unsure if it has any connection or not, but wanted to rule any possible confusion out.
Bypasses can be fascinating, I am playing with them since several decades and inspiration on my side came probably from what Inifinity, a manufacturer I like quite a lot, did - although in their case a very different matter alltogether, but well - on its LS Xover in the late 70s... And even "they" probably borrowed the idea elsewhere. As for the explanation on how it works Z impedance reduction at HF is often given, and although true from an engineering POV I suspect there is probably more to it, especialy given the LF improvements. I liked quite the works published in the late 80s / early 90s by Jean Hiraga & Co in the Audiophile on that regard, whereas they are correct or not, who knows...
Last but not least, I don't know if someone ever suggested replacing or bypassing the supercap on the Mini, but thanks for confirming my thoughts that it wouldn't anyway do anything. I left it untouched of course as far as I am concerned.
Have a nice day
Claude
Sorry for the confusion, my mistake. I misread the value of the Panasonic "upgrade" as being 3.3 Farad, not 3.3uF which made me think you replaced the Supercap.
Thanks, Ben. Really appreciate it.
Adjusted the pots and voltages on both sides for R8 & R9 checked out at zero.
I will re-bias the amplifier and see how it goes (in a few days).
Quote: "Sorry for the confusion, my mistake. I misread the value of the Panasonic "upgrade" as being 3.3 Farad, not 3.3uF which made me think you replaced the Supercap."
No issue at all... Plus I know you have a positive mindset and have ALWAYS been a great help - your comments are always welcome.
Have a nice day and thanks for having clarified the situation
Enjoy music very much
Claude
No issue at all... Plus I know you have a positive mindset and have ALWAYS been a great help - your comments are always welcome.
Have a nice day and thanks for having clarified the situation
Enjoy music very much
Claude
Here's a link to my compact SMPS filter using Mark Johnson's AmyAlice circuit. It includes an optional switch circuit to kill the power and prevent "preamp turn on thump" when used with the ACA mini.
https://www.diyaudio.com/community/...g-amyalice-circuit-design.415123/post-7735980
https://www.diyaudio.com/community/...g-amyalice-circuit-design.415123/post-7735980
Got everything working, and the amplifier is sounding sweet. Enjoying some Caetono Veloso.
Thanks again @Ben Mah!
Very curious to know how this is going. Suggestions for implementation are welcome.
-John
Hi jrKC
Will let xhitespirit / Gilles reply in detail, but below is a short answer as he is busy and then will be on the road to mine...
The short answer is it made miracles and... I have already ordered and just received the parts to build him a second (tweaked of course) Mini! Identical to the one he owns already and to mine he has "on loan" for these tests.
Gilles tried 3 different bi-amping modes (third one being a kind of bridge just to extend useable max power in all circumstances) and his reports show that vertical (V) and horizontal (H) bi-amping worked great with its Klipsch RP-8000F (that "benefit" can be very LS related!), despite no extra power being needed (we never use more than 2W). I guess harmonic distorsions and DF, among other bits, must have a thing to say...
I will let Gilles go through the details of the said benefits re sound improvement, but vertical and horizontal bi-amping sounded both as good, the Minis being really working as 4 great independant Mono channels (credits to Papa!) whatever the configuration (V or H). However, moving to only 1 (big) SMPS powering both Minis proved detrimental at his, so it is everything x2 but Gilles says it is well worth it. Will try one day at mine...
Last but not least, the kind of bridged mode I recommended trying worked "in normal listening' only as good as one single Mini soundwise (so not as good as H or V), but bettered at unsane sound levels all other configurations due to less distorsions (possibly all others are at their clipping limit)... so that we are looking into a power mode button LOL!
I hope this helps before Gilles posts his details
Claude
Will let xhitespirit / Gilles reply in detail, but below is a short answer as he is busy and then will be on the road to mine...
The short answer is it made miracles and... I have already ordered and just received the parts to build him a second (tweaked of course) Mini! Identical to the one he owns already and to mine he has "on loan" for these tests.
Gilles tried 3 different bi-amping modes (third one being a kind of bridge just to extend useable max power in all circumstances) and his reports show that vertical (V) and horizontal (H) bi-amping worked great with its Klipsch RP-8000F (that "benefit" can be very LS related!), despite no extra power being needed (we never use more than 2W). I guess harmonic distorsions and DF, among other bits, must have a thing to say...
I will let Gilles go through the details of the said benefits re sound improvement, but vertical and horizontal bi-amping sounded both as good, the Minis being really working as 4 great independant Mono channels (credits to Papa!) whatever the configuration (V or H). However, moving to only 1 (big) SMPS powering both Minis proved detrimental at his, so it is everything x2 but Gilles says it is well worth it. Will try one day at mine...
Last but not least, the kind of bridged mode I recommended trying worked "in normal listening' only as good as one single Mini soundwise (so not as good as H or V), but bettered at unsane sound levels all other configurations due to less distorsions (possibly all others are at their clipping limit)... so that we are looking into a power mode button LOL!
I hope this helps before Gilles posts his details
Claude
My Mini has been misbehaving lately.
On turn on the right channel will burp through the speakers and then will stay quiet for some time.
After turning it on and off a few times it will start playing as normal.
I suspect the two big caps, C2 & C3, most likely the output one but any suggestions are most welcome.
Thanks in advance.
On turn on the right channel will burp through the speakers and then will stay quiet for some time.
After turning it on and off a few times it will start playing as normal.
I suspect the two big caps, C2 & C3, most likely the output one but any suggestions are most welcome.
Thanks in advance.
First thing would be to monitor the midpoint voltage at power on when it should be playing but isn't. See if it is approximately correct immediately after switch on. Also check the bias current during the same time period.
Hi John
I'm been very busy at work since Friday, fixing a serious technical issue the whole world has heard about... Promise I'll report very soon.
And yes, I enjoy it, I fancy it !..
Gilles.
Hi !
Finally, my bi-amp listening sessions report. Please note all my listenings are jumpers out, as this is my preference.
Vertical bi-amp vs. mono-amp:
Horizontal bi-amp H vs. mono-amp:
Bridged vs. mono-amp:
System: DAC Eversolo Z8 / LS Klipsch RP-8000f (modified Xover)
Enjoy music !
Gilles.
Finally, my bi-amp listening sessions report. Please note all my listenings are jumpers out, as this is my preference.
Vertical bi-amp vs. mono-amp:
- The soundstage depth is clearly improved. But not simply by adding layers, this is more subtle: the sources gain thickness, the reverberation of the recording environment (room/studio) is better felt, transcribed when the recording/production quality allows it. A sort of complement in the sound message that brings truth.
- The integration of registers seems to me to be better structured, offering discernment and structure
- The midrange/voices registers gain in airiness and are less projected. The result is a more holographic presentation
- The feeling of a very clean, immaculate, purified music, yet with always this same nature of the ACA Mini. A bit like jumpers in, but with the material, the ‘grunt’ of jumpers out, without thinning (that my ears felt with jumpers in)
Horizontal bi-amp H vs. mono-amp:
- Same as horizontal bi-amp. I didn't perceive any difference (whereas I could with other amps I own).
Bridged vs. mono-amp:
- At the same volume as the above listenings (in this case -24db on my DAC), it sounds like an ACA Mini mono-amp, no difference perceived
- At -14db, the consistency one ACA displays at -24db is still preserved. The bass has punch and slam without being muddled, registers remain structured, the presentation is less cluttered, less shrill (especially in the mediums) than at -14db in mono-amping mode. A good way to get a bit more power from the ACA without compromising its musicality, but no bi-amping musicality gain.
System: DAC Eversolo Z8 / LS Klipsch RP-8000f (modified Xover)
Enjoy music !
Gilles.
While Gilles was busy at mine saving the planet or so, we couldn’t help relax a bit and comparing my (mildly tweaked) Mini to my (mildly tweaked) VFET. I know people don’t like comparisons, but for some reasons I couldn’t hold for me the conclusion I came to – skip all the rest if bored.
So, same room, same system, Gilles and I listening and coming to the same conclusions. Mini was 344mV bias and jumpers OUT - and we do know that some results would have bit altered jumpers IN (think neutrality or precision), but jumpers OUT is Gilles preferred mode with these LS and I tend to agree here.
The results are probably very LS dependant and we chose therefore our wellknown Klipsch RP-8000F as these offer a very easy drive for both amps well within their power enveloppe & Co. Yet of course SE vs Push-pull, Sony VFET vs Harris, different DF and also power delivery have something to say, but well… that’s the beauty of this comparo, isn’t it?
The results are the following. First of all the VFET and the Mini display far more similarities than differences. It is quite obvious they do come from the same stable and they are quite close... and extremely enjoyable. Generally in our humble opinion the VFET has slightly the upper hand vs one Mini, so what follows is quite subtle, but quite there aswell.
The Mini jumpers Out :
However, we “guesstimated” back then that the VFET was on objective terms playing up to the 3k class. Higher than that, even with the right LS, on objective terms, items such as neutrality, slam / dynamics or precision were a limit. However, on sujective terms, the VFET offered thanks to its amazingly airy and forgiving nature and its negative H2 something that very few amps can offer regardless the price: musicality.
We feel the same applies to the Mini. Once midly tweaked and partenered with compatible LS, we believe it plays in the up to 2k class on objective terms... while again being quite unique it terms of enjoyment. And that’s my conclusion and something I am very happy about: the Mini offers EXCELLENT VFM, something like x10 its price vs commercial offering when it comes to music only and is perhaps the only amp I know (again, partenered with compatible LS) that can offer a similar VFM than say tweaked Class D amps or other non expensive offerings that are all the modern rage nowadays. I am old guard, I know…
Guys, the Mini is a jewel at a steal price, not just for old Class A lovers.
I will build a third one for Gilles, and if Gilles is to be believed in bi-amping mode it will move even more closely to the VFET (or better it?), still at a competitive price. Of course I will give the bi-amping mode a listen.
The VFET was a lottery gift I cherish and it is a fix part of our living room’s listening system (perhaps more used than our audio room!), ensuring HIFI and AV. It isn’t available anymore. The ACA Mini is an available alternative at a more affordable price, so truly excellent VFM. And is fun to build. I just felt it needed to be typed.
ALL IMHO of course!
Enjoy music
Claude
So, same room, same system, Gilles and I listening and coming to the same conclusions. Mini was 344mV bias and jumpers OUT - and we do know that some results would have bit altered jumpers IN (think neutrality or precision), but jumpers OUT is Gilles preferred mode with these LS and I tend to agree here.
The results are probably very LS dependant and we chose therefore our wellknown Klipsch RP-8000F as these offer a very easy drive for both amps well within their power enveloppe & Co. Yet of course SE vs Push-pull, Sony VFET vs Harris, different DF and also power delivery have something to say, but well… that’s the beauty of this comparo, isn’t it?
The results are the following. First of all the VFET and the Mini display far more similarities than differences. It is quite obvious they do come from the same stable and they are quite close... and extremely enjoyable. Generally in our humble opinion the VFET has slightly the upper hand vs one Mini, so what follows is quite subtle, but quite there aswell.
The Mini jumpers Out :
- Had a bit less energy in the lowest octave, but therefore more energy in the upper bass and mids, perhaps even a bit exacerbated (groovy)
- Had less fluidity, less delicacy
- Was a tad more confused and less precise overall on complex music
- Had a tad sharper treble, sometimes rightly so, sometimes less rightly so
- Was less neutral and right re tonalities, but sooo enjoyable LOL
- Had slightly more drive/speed and slightly more slam but therefore was less relaxed / “dryer” on some occasions
- Was a tad less transparent
- And that’s it! They are quite similar on all other aspects and close re soundstage spatialization, nothing more to add but pure pleasure TBH!
However, we “guesstimated” back then that the VFET was on objective terms playing up to the 3k class. Higher than that, even with the right LS, on objective terms, items such as neutrality, slam / dynamics or precision were a limit. However, on sujective terms, the VFET offered thanks to its amazingly airy and forgiving nature and its negative H2 something that very few amps can offer regardless the price: musicality.
We feel the same applies to the Mini. Once midly tweaked and partenered with compatible LS, we believe it plays in the up to 2k class on objective terms... while again being quite unique it terms of enjoyment. And that’s my conclusion and something I am very happy about: the Mini offers EXCELLENT VFM, something like x10 its price vs commercial offering when it comes to music only and is perhaps the only amp I know (again, partenered with compatible LS) that can offer a similar VFM than say tweaked Class D amps or other non expensive offerings that are all the modern rage nowadays. I am old guard, I know…
Guys, the Mini is a jewel at a steal price, not just for old Class A lovers.
I will build a third one for Gilles, and if Gilles is to be believed in bi-amping mode it will move even more closely to the VFET (or better it?), still at a competitive price. Of course I will give the bi-amping mode a listen.
The VFET was a lottery gift I cherish and it is a fix part of our living room’s listening system (perhaps more used than our audio room!), ensuring HIFI and AV. It isn’t available anymore. The ACA Mini is an available alternative at a more affordable price, so truly excellent VFM. And is fun to build. I just felt it needed to be typed.
ALL IMHO of course!
Enjoy music
Claude
I agree with a lot of what you've said about the comparison. I especially agree with your statement about the value for money of the ACA Mini!
Hi Gilles,
This all sounds great.
But can you clarify what do you mean with "vertical and horizontal bi-amping"?
I'm trying to imagine what this involves physically.
Thanks.
Gilles is back on the road again, on his way to his...
Meanwhile, perhaps the following can help
Vertical bi-amping = one channel of a stereo amplifier for the tweeter, the other for the woofers. So each Mini is dedicated to powering just a single LS (left or right).
Horizontal bi-amping = one Mini powers the woofers of the right LS + the woofers of the left LS. The other Mini powers the tweeter of the right LS + the tweeter of the left LS.
Plenty of stuff on the internet just typing horizontal or vertical biamping. Perhaps a schematic is easier than my words? Google is your friend...
With horizontal bi-amping, often the woofers dedicated amp works harder than the other (as that's where the main energy is). On the other hand, we found often horizontal bi-amping to sound better than the channel separation champion vertical bi-amping. but just testing can tell each case being specific (on power amp and LS side) and of course personal preferences may have a say.
I hope this helps
Claude
Meanwhile, perhaps the following can help
Vertical bi-amping = one channel of a stereo amplifier for the tweeter, the other for the woofers. So each Mini is dedicated to powering just a single LS (left or right).
Horizontal bi-amping = one Mini powers the woofers of the right LS + the woofers of the left LS. The other Mini powers the tweeter of the right LS + the tweeter of the left LS.
Plenty of stuff on the internet just typing horizontal or vertical biamping. Perhaps a schematic is easier than my words? Google is your friend...
With horizontal bi-amping, often the woofers dedicated amp works harder than the other (as that's where the main energy is). On the other hand, we found often horizontal bi-amping to sound better than the channel separation champion vertical bi-amping. but just testing can tell each case being specific (on power amp and LS side) and of course personal preferences may have a say.
I hope this helps
Claude
Hi !
Thanks Claude for your reply (I'm finally back home !).
For Stanislav's understanding, maybe I would add an essential prerequisite: dual input terminals are needed on your LS to allow such configurations.
Gilles.
Thanks Claude for your reply (I'm finally back home !).
For Stanislav's understanding, maybe I would add an essential prerequisite: dual input terminals are needed on your LS to allow such configurations.
Gilles.
My son likes it a little more discreet ... ;-)
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I am using mine on a bi amped speaker project to drive a couple. 10" woofs with line level 2500 hz low pass filters. Works great so far.