A question for the Braintrust on power: The stock 04 has 35V capacitors. Would it be a bad idea to use clean, 36 V power supply (Mean Well) to power a stock 04?
I looked at the TI datasheet and see that the VDD for the TP3251 is 38 volts and Typical voltage is 36.
Based on the charts, it seems the amp gains significant power over a 24V supply.
Thoughts?
I looked at the TI datasheet and see that the VDD for the TP3251 is 38 volts and Typical voltage is 36.
Based on the charts, it seems the amp gains significant power over a 24V supply.
Thoughts?
I own the A04 with the black Tilear pcb (with Elna audio grade caps). I use a 36v / 6A PSU without any issue. You need to make sure the main power caps can support this load.
If I am not wrong the last A04 (green pcb) have some 35V /2200uf power caps.... You can update it easily ex : 50V / 3300uf (make sure to get the right size the case is small)
If I am not wrong the last A04 (green pcb) have some 35V /2200uf power caps.... You can update it easily ex : 50V / 3300uf (make sure to get the right size the case is small)
Get a 36V Meanwell (slightly) adjustable SMPS, the ones that come in a cage like look, as found in computers, and adjust down to 34V or so if you really want that high voltage.
Whereas indeed most 35V rated caps can tolerate a bit more voltage, say very slightly more, I wouldn't advise running higher than 35V as this is a hit and miss - not mentioning that we don't know what caps are now fitted inside these units, so what might have worked a certain time for one person might not be the rule for another. Further, if you run higher than 35V, than it is constantly higher than 35V as regulated PS and so life span of the caps will be shorter, and there is nothing really to be gained re power to the speakers if you do the calculation as it translates into marginal dB gains at your ears.
As already mentioned above, a safe path is to uprate all the relevant caps to 50V... but then you might question why running 35V?
I were you, I would even go for a slightly adjustable MeanWell 24V SMPS... these can be adjusted up to 29V, still more than enough voltage, deliver far more amperes if needed, or rather in our case cost less with the same ampere rating... and have far better ripple values, which matters probably the most re sound. That's what we did on Gilles 2 amps.
All IMHO...
Merry Xmas
Claude
Whereas indeed most 35V rated caps can tolerate a bit more voltage, say very slightly more, I wouldn't advise running higher than 35V as this is a hit and miss - not mentioning that we don't know what caps are now fitted inside these units, so what might have worked a certain time for one person might not be the rule for another. Further, if you run higher than 35V, than it is constantly higher than 35V as regulated PS and so life span of the caps will be shorter, and there is nothing really to be gained re power to the speakers if you do the calculation as it translates into marginal dB gains at your ears.
As already mentioned above, a safe path is to uprate all the relevant caps to 50V... but then you might question why running 35V?
I were you, I would even go for a slightly adjustable MeanWell 24V SMPS... these can be adjusted up to 29V, still more than enough voltage, deliver far more amperes if needed, or rather in our case cost less with the same ampere rating... and have far better ripple values, which matters probably the most re sound. That's what we did on Gilles 2 amps.
All IMHO...
Merry Xmas
Claude
Thanks, Gents.
I may need to tin my soldering iron and make some mods.
Best wishes to you, as well, for a Merry Christmas et Joyeux Noël!
Attachments
Hi I'm new here.
I have A04 v2.1 and the latest v3.1 which most disapprove of.
It came with low gain and pop noise when turned off.
I followed Aiyima's recommendation and removed the 4 resistors under the heatsink. The gain increased, and the pop noise when turning off disappeared, but now there is pop noise when turning on.
It is not strong and appears 3 seconds after turning it on.
I really want to delete it, any ideas?
Thanks
I have A04 v2.1 and the latest v3.1 which most disapprove of.
It came with low gain and pop noise when turned off.
I followed Aiyima's recommendation and removed the 4 resistors under the heatsink. The gain increased, and the pop noise when turning off disappeared, but now there is pop noise when turning on.
It is not strong and appears 3 seconds after turning it on.
I really want to delete it, any ideas?
Thanks
I have that model too, without the resistors and with the opas1656 and it doesnt make any pop neither when turning on or off
Reviving an old thread, 2 more posts of mine based on recent experience with these little units - note the "old tweaked versions" of ours.
First off, I had a proper listen to the very mildly tweaked version my mother is using. These lightweight tweaks already described in the past are giving the best results for only 20E parts and only 1h work.
This amp is used since over one year with a very cheap SMPS (18E). It is really a good unit. My mother was / is a world class opera singer, so quite demanding in some areas. Whereas in most areas this amp beat the old H-K amp I tweaked back then for her, it wasn't better in all departments. Still something lacking. Something to do with pitch correctness and fluidity. Listening to it I confirmed it.
This amp is used without PS filter and Gilles did a recent test on his widely tweaked units, removing and fitting the PS filters of my own (very early posts). Clearly now that the unit is extensively tweaked the benefits of the filter are clearlky more apparent and he would rate the benefits higher (give more points) on a unit that has moved into another audio class.
Triggered by this I decided to use Mark's excellent SMPS filter as a quick test between the cheap SMPS and my mother's amp. YOU SHOULDN'T DO THAT. It was a quick test with well known quantities, as Mark's filter is only rated for 3A! Mine is though fitted with parts that can resist 6A, the board is probably safe and the LS we use are quite sensitive so that we use less than 1W in real listening situations! So we don't draw a lot of amperes on average.
I fitted Mark's filter in several units and it always shone. Either with quite tremendous benefits, worst case with no negative. Daisy chaining more of them was though not a clear cut. Here, the filter brought a great benefit, appreciated by my mother: timbre correctness. Once the filter fitted, music tonality / pitch became very slightly different. In fact, lsitening carefully with and without, it was like like all the register was shifted by a half tone and... sounded now correct! That was it, really changing the pleasure and correctness of the music! This filter brought "while at it" very slightly more liquidity to the sound, better note endings, and slightly better treble. Mids were unaffected. SADLY, the bass department became wanting : quite a bit of impulsivness, impact and also low bass extension was robbed away, like taken out. Let's not forget this excellent SMPS filter wasn't designed for this high ampere application, is working out of his range and eventhough we don't need that much power the only explanation I can see is that the Class D impulse feeds are slowed down somehow, robbing dynamic and energy. Possibly the Class D, although in our case not energy demanding on average, requires quite large feed impulses that aren't the filter's forte and that the PS caps / energy resrevoir can't compensate despite our HF bypasses.
We know from past experience with filters that filters can sometime give the slight impression of less bass and imulse, but that's a (little) side effect probably due to less distorsion in that department, so slightly less energy and more cleaness. Here we have clearly something different at play, something negative. I removed the filter and remembered that "my" filters, designed back then for this amp, do just very slighly that aswell (less distorsions), but with absolutely no negative whatsoever in the bass department, on the contrary.
Bottom line: fit a decent external SMPS filter to enhence your experience on a mildly tweaked unit. It needs quite some capacity (energy) and mandatory indictances IMHO as only these IME filter out properly HF. That will be my next Xmas gift for this amp...
Enjoy music
Claude
First off, I had a proper listen to the very mildly tweaked version my mother is using. These lightweight tweaks already described in the past are giving the best results for only 20E parts and only 1h work.
This amp is used since over one year with a very cheap SMPS (18E). It is really a good unit. My mother was / is a world class opera singer, so quite demanding in some areas. Whereas in most areas this amp beat the old H-K amp I tweaked back then for her, it wasn't better in all departments. Still something lacking. Something to do with pitch correctness and fluidity. Listening to it I confirmed it.
This amp is used without PS filter and Gilles did a recent test on his widely tweaked units, removing and fitting the PS filters of my own (very early posts). Clearly now that the unit is extensively tweaked the benefits of the filter are clearlky more apparent and he would rate the benefits higher (give more points) on a unit that has moved into another audio class.
Triggered by this I decided to use Mark's excellent SMPS filter as a quick test between the cheap SMPS and my mother's amp. YOU SHOULDN'T DO THAT. It was a quick test with well known quantities, as Mark's filter is only rated for 3A! Mine is though fitted with parts that can resist 6A, the board is probably safe and the LS we use are quite sensitive so that we use less than 1W in real listening situations! So we don't draw a lot of amperes on average.
I fitted Mark's filter in several units and it always shone. Either with quite tremendous benefits, worst case with no negative. Daisy chaining more of them was though not a clear cut. Here, the filter brought a great benefit, appreciated by my mother: timbre correctness. Once the filter fitted, music tonality / pitch became very slightly different. In fact, lsitening carefully with and without, it was like like all the register was shifted by a half tone and... sounded now correct! That was it, really changing the pleasure and correctness of the music! This filter brought "while at it" very slightly more liquidity to the sound, better note endings, and slightly better treble. Mids were unaffected. SADLY, the bass department became wanting : quite a bit of impulsivness, impact and also low bass extension was robbed away, like taken out. Let's not forget this excellent SMPS filter wasn't designed for this high ampere application, is working out of his range and eventhough we don't need that much power the only explanation I can see is that the Class D impulse feeds are slowed down somehow, robbing dynamic and energy. Possibly the Class D, although in our case not energy demanding on average, requires quite large feed impulses that aren't the filter's forte and that the PS caps / energy resrevoir can't compensate despite our HF bypasses.
We know from past experience with filters that filters can sometime give the slight impression of less bass and imulse, but that's a (little) side effect probably due to less distorsion in that department, so slightly less energy and more cleaness. Here we have clearly something different at play, something negative. I removed the filter and remembered that "my" filters, designed back then for this amp, do just very slighly that aswell (less distorsions), but with absolutely no negative whatsoever in the bass department, on the contrary.
Bottom line: fit a decent external SMPS filter to enhence your experience on a mildly tweaked unit. It needs quite some capacity (energy) and mandatory indictances IMHO as only these IME filter out properly HF. That will be my next Xmas gift for this amp...
Enjoy music
Claude
We always wanted to compare our tweaked unit to a well known entity, a benchmark in the integrated amp market. It never materialised, Covid etc.
However, Gilles had the opportunity to compare extensively 3 amps in his system, for an unlimited time, brought together :
I will spare you (and me) with the detailled report, but bottom lines are :
Bottom lines, all IN OUR EXPERIENCE... and just talking sound, not features, packaging, quality etc
Untweaked, a single 04 plays slightly under the very best VFM integrated amps costing new 600E. It is doing a good job, but just that compared with the best current units... still excellent VFM obviously.
Extensively tweaked, with 2 in one amp (which only increases slightly the sonic benefits) it can compete with the best amps in the 1500-2000E bracket.
You really need to spend North of 2500E to slightly beat the tweaked units.
For those reading the excellent German mag AUDIO, on which my own point system is based since decades, this would translate into the following points in their ranking system:
We would love to find this out, trying a shootout vs the latest NAD for example, but it isn't easy.
Oh, and I rate the VFET higher in all departments or nearly so, and that is just taking stone cold parameters into considerations (bass department, soundstagfe etc.) - if considering his charm / euphonic effect, then...but that's another story!
Enjoy music with this nice little unit
Claude
However, Gilles had the opportunity to compare extensively 3 amps in his system, for an unlimited time, brought together :
- his amps, so 2 x 04 amps in one amp, tweaked extensively as described in this thread
- a modern Onkyo amp, best buy in the 1000$ bracket, well known for his neutrality and lack of any drawback, at the cost of not sounding as engaging as the upper class amp
- My Pass VFET amp
I will spare you (and me) with the detailled report, but bottom lines are :
- the numerous tweaks we did on Gilles amps didn't alter the tonal balance, both his amp and the Onkyo sounding very very similar in that regard. It is great to know ours ears are working and we didn't drift away re sound definition
- the 04s shone in every department, it had a slight edge everywhere and no negative in whatever department whatsoever vs the Onkyo
- in comparison to the Onkyo it scored the most in the bass department (impact, definition, control), mids (voices more realistic and defined), and treble (less sibilants). On top, it is more transparent / revealing to music.
- We didn't expect that, but in terms of speed the Onkyo was quite on a par. It accelerates as fast (leading edge), but control isn't as good at note endings, especialy on complex passages.
- Regarding soundstage, widness was the same, but quite suprisingly height and depth were better on the Class D.
Bottom lines, all IN OUR EXPERIENCE... and just talking sound, not features, packaging, quality etc
Untweaked, a single 04 plays slightly under the very best VFM integrated amps costing new 600E. It is doing a good job, but just that compared with the best current units... still excellent VFM obviously.
Extensively tweaked, with 2 in one amp (which only increases slightly the sonic benefits) it can compete with the best amps in the 1500-2000E bracket.
You really need to spend North of 2500E to slightly beat the tweaked units.
For those reading the excellent German mag AUDIO, on which my own point system is based since decades, this would translate into the following points in their ranking system:
- Onkyo tested at 90 points
- Gilles amp deserves a solid 105 points. Note a single 04 amp would possibly be in the 100+ area, a midly tweaked 04 possibly slightly under 100...
- Gilles amp would be a very solid contender in the 1500-2000E bracket
- I personaly find that amps, once they match well with speakers, do less difference than speakers or sources and whereas on these latters I can clearly perceive 5 point class jumps, when it comes to amps things get more subtle (from a ceratin level on) and I need 10 points jumps to make a small difference. Based on this Gilles would need to spend possibly North of 2500E to beat his amp.
We would love to find this out, trying a shootout vs the latest NAD for example, but it isn't easy.
Oh, and I rate the VFET higher in all departments or nearly so, and that is just taking stone cold parameters into considerations (bass department, soundstagfe etc.) - if considering his charm / euphonic effect, then...but that's another story!
Enjoy music with this nice little unit
Claude
Hello Claude, I read with fascination what you wrote. My English is not very good and I could only partially understand what was written. I have an A04 with a black PCB. Is a simple and effective enhancement applied to a black PCB?. Can you tell me the parts list and which ones to replace?
From a purely theoretical point of view, I think that the ASR measurements already give us some clues about the A07 in its stock version...
A04 :
Not so bad for a desktop amplifier )
But if you consider the ratio performance / price, get the PA5 based on the same TPA3255 chip, It has nothing to do with it .... we know why we pay the price difference) And there, we can say that we are approaching an Benchmark AHB2 for one tenth of its price)
And these are the measurements with the basic power brick... imagine with a good quality power supply with a ripple worthy of the name!
PA5 :
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Hi Welder911
I don't have played with black PCB amps, in fact I don't even own this amp myself.
BUT, from what I read here, my understanding is that most if not all mods we did are applicable to that black board amp aswell.
You could start with the light mods (40% work and cost for 80% results or so) as I did for example on my mother's amp, and see how you fare. Then if you fancy it you could still push the further as on the 2 amps we did for Gilles.
I am no more really active on this thread... For details on what to do and what parts to use, please use the search function for my posts in this thread: I posted on all this in a very detailled way. I even summarised somewhere the light version mods.
Good luck
Claude
I don't have played with black PCB amps, in fact I don't even own this amp myself.
BUT, from what I read here, my understanding is that most if not all mods we did are applicable to that black board amp aswell.
You could start with the light mods (40% work and cost for 80% results or so) as I did for example on my mother's amp, and see how you fare. Then if you fancy it you could still push the further as on the 2 amps we did for Gilles.
I am no more really active on this thread... For details on what to do and what parts to use, please use the search function for my posts in this thread: I posted on all this in a very detailled way. I even summarised somewhere the light version mods.
Good luck
Claude
Hi Daniboun,
Yep, encouraging perhaps... but, err, this is (or was) a thread about 04 and not 07. It uses a different core / chip amp (TPA3251 and not TPA3255), to start with (not mentioning implementation etc.). Same extended family of TI Class D chip amps, but different animal for different needs - alone on the spec sheet, not mentioning other real life bits.
As for ASR's measurements... according to these, all the amps you have built and purchased since a couple of years should sound the same (or nearly so) to human ears (that are supposed to be inferior to their gear, not only different so they claim)...
I don't know for you, but that didn't work in my case, absolutely not, be it for their ranking of amps or theirs for DACs.
Pity, I would really have loved the world would be that simple: we would all have perfect amps for peanuts money... Ok, perhaps with a different front end to suit our sonic preferences... but NO, not to my experience.
Gilles is still using on a daily basis his (trully engaging and nice sounding) bi-amp tweaked 04 at his, side by side with my VFET that measures really HORRIBLY to ASR standards. Same source, same loudspeakers. Although there is really no loser here, I know which amp I would keep without hesitation... AND GILLES, IF YOU READ THIS, YES, "THAT ONE" IS ON LOAN GLOL!
I am an old engineer that ended up in Formula 1 and really love measurements and data... really a lot, believe me... but only the ones that are really usefull to me. I learned that with time, but that's another debate...
“Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted.” -Albert Einstein
Have a fun day
Claude
Yep, encouraging perhaps... but, err, this is (or was) a thread about 04 and not 07. It uses a different core / chip amp (TPA3251 and not TPA3255), to start with (not mentioning implementation etc.). Same extended family of TI Class D chip amps, but different animal for different needs - alone on the spec sheet, not mentioning other real life bits.
As for ASR's measurements... according to these, all the amps you have built and purchased since a couple of years should sound the same (or nearly so) to human ears (that are supposed to be inferior to their gear, not only different so they claim)...
I don't know for you, but that didn't work in my case, absolutely not, be it for their ranking of amps or theirs for DACs.
Pity, I would really have loved the world would be that simple: we would all have perfect amps for peanuts money... Ok, perhaps with a different front end to suit our sonic preferences... but NO, not to my experience.
Gilles is still using on a daily basis his (trully engaging and nice sounding) bi-amp tweaked 04 at his, side by side with my VFET that measures really HORRIBLY to ASR standards. Same source, same loudspeakers. Although there is really no loser here, I know which amp I would keep without hesitation... AND GILLES, IF YOU READ THIS, YES, "THAT ONE" IS ON LOAN GLOL!
I am an old engineer that ended up in Formula 1 and really love measurements and data... really a lot, believe me... but only the ones that are really usefull to me. I learned that with time, but that's another debate...
“Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted.” -Albert Einstein
Have a fun day
Claude
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You are right after all ) Maybe is not the right thread to talk about the PA5. But just mentioned it because it using the same TPA325X chip.
I appreciate your feedback and thanks for all you did for the members here.
Stay safe and see ya )
Danny