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Sorry, I think we are getting confused I was also asking what values has Claude changed his output caps to?
My new build is getting:
1) My power caps = 3300 uF
2) Inductors = 10 uH
3) Output filters 0.68 uF and or 1 uF (I'm trying both)
The biggest issue is size, there's a very LIMITED amount of space to work with.
Plus a few other things...
Rob43
OK lilolee, posting again as same LS as my friend's...
Of course you do as you want, I hope merely all has been considered on your side...
"While at it, it would be pity not to reconsider the entire output filter (read caps and coils) and of course to adapt the unit to the LS. These are quite specific and have around 10 Ohm between 10 and 20kHz, so that requires some unusual calculations.
Long story short, as sadly compatible 12.5uH quality coils at Mouser's don't seem to exist, I will have to play with 10uH and 15uH coils... and also with the caps value that are available in MKP (don't want to start adding caps in parallel to get the perfect exotic value). That leaves me with 2 choices, as the 12.5uH / 0.25uF combo doesn't exist in real life...
1) 10uH / 0.22uF, very good results up to 20kHz and far beyond (quite free wide band response), sadly cut frequency perhaps unusaly high at 107kHz but still 24dB attenuation at 400kHz and 32dB at 600kHz (carrier of the Class D chip).
I like that unusual choice as still resonable coil re distorsion and losses and size, it gives a very good Q... the only downside I see is the cut frequency is a bit high in absolute terms, but have no clue if that's a real problem as I never played with Class D.
2) Classical choice by the book, 15uH/0.3uF, perfect Q, Fc at 75kHz, -34dB at carrier's frequency, as for 1 less than 0.1dB deviation at 20kHz : the "computer's choice"... and a choice that is also more acceptable for different LS. So what's wrong with it? Well, a similar sized 15uH coil is likely to be less performing in audio terms than a 10uH one (distorsion & Co), and it is all about audio performance, isn't it? Hence option 1's existence... especialy as its only downside is mainly (only) 4dB less damping at the carrier's frequency while it therefore still keeps output coils reasonably sized... "
In short, if you go 10uH coil with the Klipsch look at what would happen if you don't change the cap value aswell and or move to 1uF...
Hint, with your LS and 1uF you get a 2dB peak at 20kHz (bright sounding) and a +4dB at 40kHz peak, not great at all mate...
Oh and with 0.68uF it is slightly better, but still not great for the 10R you are considering in the treble band...
Good luck
Claude
Of course you do as you want, I hope merely all has been considered on your side...
"While at it, it would be pity not to reconsider the entire output filter (read caps and coils) and of course to adapt the unit to the LS. These are quite specific and have around 10 Ohm between 10 and 20kHz, so that requires some unusual calculations.
Long story short, as sadly compatible 12.5uH quality coils at Mouser's don't seem to exist, I will have to play with 10uH and 15uH coils... and also with the caps value that are available in MKP (don't want to start adding caps in parallel to get the perfect exotic value). That leaves me with 2 choices, as the 12.5uH / 0.25uF combo doesn't exist in real life...
1) 10uH / 0.22uF, very good results up to 20kHz and far beyond (quite free wide band response), sadly cut frequency perhaps unusaly high at 107kHz but still 24dB attenuation at 400kHz and 32dB at 600kHz (carrier of the Class D chip).
I like that unusual choice as still resonable coil re distorsion and losses and size, it gives a very good Q... the only downside I see is the cut frequency is a bit high in absolute terms, but have no clue if that's a real problem as I never played with Class D.
2) Classical choice by the book, 15uH/0.3uF, perfect Q, Fc at 75kHz, -34dB at carrier's frequency, as for 1 less than 0.1dB deviation at 20kHz : the "computer's choice"... and a choice that is also more acceptable for different LS. So what's wrong with it? Well, a similar sized 15uH coil is likely to be less performing in audio terms than a 10uH one (distorsion & Co), and it is all about audio performance, isn't it? Hence option 1's existence... especialy as its only downside is mainly (only) 4dB less damping at the carrier's frequency while it therefore still keeps output coils reasonably sized... "
In short, if you go 10uH coil with the Klipsch look at what would happen if you don't change the cap value aswell and or move to 1uF...
Hint, with your LS and 1uF you get a 2dB peak at 20kHz (bright sounding) and a +4dB at 40kHz peak, not great at all mate...
Oh and with 0.68uF it is slightly better, but still not great for the 10R you are considering in the treble band...
Good luck
Claude
Claude, thanks for that. I assumed there must be a SPICE model for the output relationship of Inductor/Cap.
On the TI site and in Rich's posts there is mention of the TI calculation program (excel sheet in fact) to dimension the output filter.
Link is also in their chip papers somewhere, can't remember if it was evaluation board but believe so... or just Google TI and Class D output filter.
No need for spice model & co
Link is also in their chip papers somewhere, can't remember if it was evaluation board but believe so... or just Google TI and Class D output filter.
No need for spice model & co
That's the one 🙂
Just an advice, use it wisely and if not done read before the LC Filter design paper (SLAA701A)... lot of valuable info there to know what to do, why... and what not 🙂
Claude
Just an advice, use it wisely and if not done read before the LC Filter design paper (SLAA701A)... lot of valuable info there to know what to do, why... and what not 🙂
Claude
I replaced the stock 5532's with guaranteed genuine devices from TI via Mouser, though I have to say I didn't hear a difference. I also tried out a pair of OPA1656's and after swapping out the opamps a few times, I have to say I prefer the 5532's (my ears, etc.). So yeah, Frabor is right: the 5532 is a great chip. I've removed the Aiyima board from its case and put it into a flimsy (though bigger) enclosure so I can utilize better RCA jacks and heavy duty speaker binding posts; the binding posts are the Aiyima's worst annoyance, IMO. I don't plan on "improving" it any further, other than maybe trying out other plug-in opamps. The PSU is a MW 24V set @ 27V. One set of stereo inputs, so I either plug in my phono pre or CD/DAC direct, caveman style. I've got more than a 100 classical LPs that I've never listened to lined up for listening, so one input is fine for now.
My DIY FW F4 is at an altogether higher level of refinement, using either an LTA MZ2 or Wayne's BA2018 preamp, but the Aiyima is just what I need during our hot summers. It's a very good amp, regardless of cost.
I'll probably try other opamps in the future, but only full size versions--or maybe SMDs that have been pre-mounted on an adapter. I hate hate hate the Chip Quik PA0001 SOIC-8 to DIP-8 SMT adapter! What a miserable experience. That might have soured my impressions of the 1656. 😀
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Chip Quik PA0001
I can see why, glad I designed my own. They should have rotated the so-8 ninety degrees. I put a decoupling cap 0805 across the supply pins as well. There’s takes up too much area and the pins are 25mil sq, wrong too
I can see why, glad I designed my own. They should have rotated the so-8 ninety degrees. I put a decoupling cap 0805 across the supply pins as well. There’s takes up too much area and the pins are 25mil sq, wrong too
Yeah, I'd like to see how you made yours. I almost considered hand-wiring everything but that was a moment of madness. I had to snip off bits of PCB to ensure decent contact. Horrible!
So finaly we decided to give that little unit a try. Or shall we rather say 2 little units a try ?
Short version, all in our humble opinion, UNTWEAKED :
- This Chinese Class D amp is an incredible bargain worth probably up to 6 times its price, once again…
- It is not a giant killer, a regular 400E amp beats it
- It is a fun amp with some slight euphonic effect
- It has tremendous potential to improve, starting with its very poor volume potentiometer
- 2 units can probably hold position in the up to 1000E integrated amp class in terms of sonic qualities
- Tweaked who knows what it/they can deliver, to be followed
The long version…
Disclaimer ! I have no link whatsoever with the manufacturer or others and I am in fact personaly not directly interested in any Class D device, being busy on other amp projects. The reports posted here attracted my interest and an excellent friend of mine wanted to refurbish an old amp with something different, hence us starting this as a fun project. I did not give it yet personaly a listen as the purpose was to see first how this amp would perform at the owners ears (eg reports below), to then tune it together accordingly. Having said that, I know the owner since 15y, he has a classical education (piano player), still plays the guitar today and is used to listening to hifi systems with me and others with quite similar findings and tastes. In short, I trust him every bit and at the end it is FOR HIM anyway. The limit would perhaps be he is not as experienced when it comes to high end systems and nuances, but then the unit and system are the limit anyway… and on the other side he is used to listening to real instruments.
The Aiyima TPA 3251 amp(s) was / were tried on different LS and in comparison to a recently purchased Onkyo TX-8250 he owns aswell.
Final evalutation was done on the Klipsch RP-8000F, perhaps the most neutral sounding of the modern Klipsch lines which were IMHO until recently more home theater orientated. They represent an easy load for amps and are quite fine speakers, good VFM at their normal price and in fact a steal for the less than 700E delivered he paid for (new). There is little to moan about them but perhaps a tad front projections at the cost of stage depth.
The Onkyo was also purchased new at a reduced price (around 400E) and is amongst the very best integrated amps (or rather receiver) in the 700E class. It is difficult to say how it sounds in isolation despite having been tried on Klipsch and Audio Monitors, but based on reviews and cross checks it seems to be in terms of sound quality on a par with a unit I know quite well, the Accuphase E-206, with perhaps the modern sound signature, eg slightly more resolution at the cost of some musicality / maturity… perhaps.
Anyway 2 Class D amps were purchased for around 40E each and are fed by a low ripple Meanwell SMPS with up to 29V and 14.6A (say another 40E) so it can easily drive both amps if needed. Of course PS and many other things will be tuned, but at that first stage the question was « is it worth keeping these little amps and tweaking them ? ».
Basicaly, this is comparing a single 80E unit (amp+PS) with say a classical Class A/B up to 400E integrated amp (the Onkyo came new at a reduced price from 580E to 400E and includes a DAC, a tuner, and Blutooth and many other goodies that probably cost at least 100E,not to mention build quality). And a combo of 2 amps in 2 configurations (cost around 120E) vs the Onkyo. Only sound mattered, not quality or features.
Now to the listening impressions, after burn-in and several tries in different configurations and set-ups since many days and nights. S stands for a single Class D amp (in biwiring LS mode), V for 2 units in vertical bi-amping, H for 2 units in horizontal bi-amping. By bi-amping it is understood 2 amps while keeping the LS passive crossover, another path for improvement perhaps would be an active crossover at some stage(?).
Anyway, the small amps were tested unopened as they came, were also compared each other (just to make sure they sound the same) and of course tuning them would probably bring a different result – we hope so, we have quite a few ideas in mind. LS wires were the same for all configurations and the ones I use in my very own reference system, so neutral and big enough to carry any juice J
While adjusting volumes and testing, it was noted how poor the standard potentiometers were performing in the small amps. It is difficult to adjust/match volume precisely at low levels and as in the past I am convinced based on my experience that these pots are robbing a lot of music. But anyway, we said untouched for the moment…
As a baseline to outline the magnitude of the plus and minus, we chose +5 as a reference, that score eing the perceived difference equivalent to the swap from a no name electrolytic caps to top brand polyprop one (with associated resistance) in a LS crossover for mids or treble. I would say quite a change even non trained ears would immediately detect, while not being over 1 class upgrade in terms of hardware so still fine/subtle enough.
The results are as follows, the Onkyo being the absolute baseline (score = 0) for this shoot out and not taking into account its possibly « somewhat dry /analytical» caracter. Oh, and the source was always the Onkyo’s line out (so its DAC), so all units having the same inputs and acting solely as integrated amps in fact (bare the RCA connections for the non Onkyo configurations).
Stage width
Stage depth
Sound amplitude/energy, bass and lower medium
Precision, bass and lower medium
Resolutions/ details middle and treble
Dryness treble
Of course some more text is required to describe a unit, the overall perception and integration of music etc. At the end all are fun and worth the money. We are talking nuances here, not worlds, but we believe H can probably equal or beat from factory the Onkyo in terms of sonic performance on these LS. In fact the Onkyo sounds mature and integrates all the sound quite well with no real flaws, whereas the small amps show more caracter and fun factor but are less equal in performance, though overall good performers. Bottom line : they are somewhat raw and need some audiophile care, tweaks we come...
H is in our case the configuration to keep in mind, but we will tune units separately step by step to be able to monitor any change. We haven’t decided yet if the tweaks will be compatible with the existing housing and footprint or if we go « open » as anyway integrated in an old casing.
Enjoy music
Claude (or rather Gilles for the source J)
Short version, all in our humble opinion, UNTWEAKED :
- This Chinese Class D amp is an incredible bargain worth probably up to 6 times its price, once again…
- It is not a giant killer, a regular 400E amp beats it
- It is a fun amp with some slight euphonic effect
- It has tremendous potential to improve, starting with its very poor volume potentiometer
- 2 units can probably hold position in the up to 1000E integrated amp class in terms of sonic qualities
- Tweaked who knows what it/they can deliver, to be followed
The long version…
Disclaimer ! I have no link whatsoever with the manufacturer or others and I am in fact personaly not directly interested in any Class D device, being busy on other amp projects. The reports posted here attracted my interest and an excellent friend of mine wanted to refurbish an old amp with something different, hence us starting this as a fun project. I did not give it yet personaly a listen as the purpose was to see first how this amp would perform at the owners ears (eg reports below), to then tune it together accordingly. Having said that, I know the owner since 15y, he has a classical education (piano player), still plays the guitar today and is used to listening to hifi systems with me and others with quite similar findings and tastes. In short, I trust him every bit and at the end it is FOR HIM anyway. The limit would perhaps be he is not as experienced when it comes to high end systems and nuances, but then the unit and system are the limit anyway… and on the other side he is used to listening to real instruments.
The Aiyima TPA 3251 amp(s) was / were tried on different LS and in comparison to a recently purchased Onkyo TX-8250 he owns aswell.
Final evalutation was done on the Klipsch RP-8000F, perhaps the most neutral sounding of the modern Klipsch lines which were IMHO until recently more home theater orientated. They represent an easy load for amps and are quite fine speakers, good VFM at their normal price and in fact a steal for the less than 700E delivered he paid for (new). There is little to moan about them but perhaps a tad front projections at the cost of stage depth.
The Onkyo was also purchased new at a reduced price (around 400E) and is amongst the very best integrated amps (or rather receiver) in the 700E class. It is difficult to say how it sounds in isolation despite having been tried on Klipsch and Audio Monitors, but based on reviews and cross checks it seems to be in terms of sound quality on a par with a unit I know quite well, the Accuphase E-206, with perhaps the modern sound signature, eg slightly more resolution at the cost of some musicality / maturity… perhaps.
Anyway 2 Class D amps were purchased for around 40E each and are fed by a low ripple Meanwell SMPS with up to 29V and 14.6A (say another 40E) so it can easily drive both amps if needed. Of course PS and many other things will be tuned, but at that first stage the question was « is it worth keeping these little amps and tweaking them ? ».
Basicaly, this is comparing a single 80E unit (amp+PS) with say a classical Class A/B up to 400E integrated amp (the Onkyo came new at a reduced price from 580E to 400E and includes a DAC, a tuner, and Blutooth and many other goodies that probably cost at least 100E,not to mention build quality). And a combo of 2 amps in 2 configurations (cost around 120E) vs the Onkyo. Only sound mattered, not quality or features.
Now to the listening impressions, after burn-in and several tries in different configurations and set-ups since many days and nights. S stands for a single Class D amp (in biwiring LS mode), V for 2 units in vertical bi-amping, H for 2 units in horizontal bi-amping. By bi-amping it is understood 2 amps while keeping the LS passive crossover, another path for improvement perhaps would be an active crossover at some stage(?).
Anyway, the small amps were tested unopened as they came, were also compared each other (just to make sure they sound the same) and of course tuning them would probably bring a different result – we hope so, we have quite a few ideas in mind. LS wires were the same for all configurations and the ones I use in my very own reference system, so neutral and big enough to carry any juice J
While adjusting volumes and testing, it was noted how poor the standard potentiometers were performing in the small amps. It is difficult to adjust/match volume precisely at low levels and as in the past I am convinced based on my experience that these pots are robbing a lot of music. But anyway, we said untouched for the moment…
As a baseline to outline the magnitude of the plus and minus, we chose +5 as a reference, that score eing the perceived difference equivalent to the swap from a no name electrolytic caps to top brand polyprop one (with associated resistance) in a LS crossover for mids or treble. I would say quite a change even non trained ears would immediately detect, while not being over 1 class upgrade in terms of hardware so still fine/subtle enough.
The results are as follows, the Onkyo being the absolute baseline (score = 0) for this shoot out and not taking into account its possibly « somewhat dry /analytical» caracter. Oh, and the source was always the Onkyo’s line out (so its DAC), so all units having the same inputs and acting solely as integrated amps in fact (bare the RCA connections for the non Onkyo configurations).
Stage width
- V: 0
- H: -1. Note : in fact as large as Onkyo but less lineary defined at the edges
- S: -2
Stage depth
- V: -1
- H: +1
- S: -2
Sound amplitude/energy, bass and lower medium
- V : +4. Note: slight euphonic though, but still fun and on the good side
- H: +3. Note : fun and perhaps more neutral
- S +3. Note identical to H
Precision, bass and lower medium
- V : -3. It is warm and fun, but too much and muddy/not that precise vs the Onkyo
- H :+1. Neutral, resolving while fun
- S : -3 Close to V
Resolutions/ details middle and treble
- V : -2. Fine but lacks finesse
- H : +1. Quite good in fact
- S :-2. Identical to V
Dryness treble
- V : -1
- H : 0
- S : -1
Of course some more text is required to describe a unit, the overall perception and integration of music etc. At the end all are fun and worth the money. We are talking nuances here, not worlds, but we believe H can probably equal or beat from factory the Onkyo in terms of sonic performance on these LS. In fact the Onkyo sounds mature and integrates all the sound quite well with no real flaws, whereas the small amps show more caracter and fun factor but are less equal in performance, though overall good performers. Bottom line : they are somewhat raw and need some audiophile care, tweaks we come...
H is in our case the configuration to keep in mind, but we will tune units separately step by step to be able to monitor any change. We haven’t decided yet if the tweaks will be compatible with the existing housing and footprint or if we go « open » as anyway integrated in an old casing.
Enjoy music
Claude (or rather Gilles for the source J)
Hello Claude,
May I ask if you used switches so that you could change from one amp to another instantly?
Cheers - Jem
May I ask if you used switches so that you could change from one amp to another instantly?
Cheers - Jem
You talk about 400E and 1000E Amplifiers - Could you confirm what Amplifiers these are and what make ? I am sorry but too many manufacturers use the same names !!!
Also in each of your set ups the Aiyima can I confirm that for all the configurations that the amplifiers were being fed the full range of frequencies and only the speaker crossovers were defining what was fed to the drivers ? So the differences are more to do with the load presented by each speaker driver (through the crossover) rather than the signal fed to the amplifiers which I guess needed to be split to feed two amplifiers ?
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Hi Jem,
No switch, banana plugs and RCA plugs splitters, very quickly done, all is very accessible. Banana won't stay, they are only used during this evaluation phase.
Hi Bushellj,
As stated, the reference amp is the Onkyo TX-8250, regulary priced at 580E and purchased new at 400E. According to Audio and other mags it plays easily in the 600E to 900E league, see their ranking. Other mags praised it aswell...
1000E class, only mentioned a possibility ("can probably"), not any test performed. Despite having quite a few amps for that, it is for us pointless to compare further considering the current sonic quality range: the Onkyo is the right ball park for the moment (untweaked little units). Plus anyway the only reference point here as the other amps I have in mind are not own by the owner of these units and at the end it is all done for him. So from this working point on we will only try to assess potential progress based on the standard Aiyima (or whatever derivative we may take as baseline). No other comparison with commercial amps, nor will I unplugged my beloved amp or carry the one I am building for me ;-)
Regarding your second point, you are correct: amps where fed with full range of frequencies, as stated no active crossover... perhaps one day, thinking NP, the Klipsch are 2 way LS ;-)... could be a nice present for a friend but unsure yet if worth getting that far with such a system, not to mention potential warranty issues all this being brand new and not mine. I will just hold the soldering iron 🙂
Thanks for reading me
Claude
No switch, banana plugs and RCA plugs splitters, very quickly done, all is very accessible. Banana won't stay, they are only used during this evaluation phase.
Hi Bushellj,
As stated, the reference amp is the Onkyo TX-8250, regulary priced at 580E and purchased new at 400E. According to Audio and other mags it plays easily in the 600E to 900E league, see their ranking. Other mags praised it aswell...
1000E class, only mentioned a possibility ("can probably"), not any test performed. Despite having quite a few amps for that, it is for us pointless to compare further considering the current sonic quality range: the Onkyo is the right ball park for the moment (untweaked little units). Plus anyway the only reference point here as the other amps I have in mind are not own by the owner of these units and at the end it is all done for him. So from this working point on we will only try to assess potential progress based on the standard Aiyima (or whatever derivative we may take as baseline). No other comparison with commercial amps, nor will I unplugged my beloved amp or carry the one I am building for me ;-)
Regarding your second point, you are correct: amps where fed with full range of frequencies, as stated no active crossover... perhaps one day, thinking NP, the Klipsch are 2 way LS ;-)... could be a nice present for a friend but unsure yet if worth getting that far with such a system, not to mention potential warranty issues all this being brand new and not mine. I will just hold the soldering iron 🙂
Thanks for reading me
Claude
Hello Claude,
Unplugging re-plugging not very good at all in fact quite worthless. May I suggest with respect you read this from a far better authority than me, it's an 8 page article the last two pages deal with how and why a proper subjective evaluation should be done with switches (instantly) JLH 1969 Original Article.pdf - Google Drive
Cheers - Jem
Unplugging re-plugging not very good at all in fact quite worthless. May I suggest with respect you read this from a far better authority than me, it's an 8 page article the last two pages deal with how and why a proper subjective evaluation should be done with switches (instantly) JLH 1969 Original Article.pdf - Google Drive
Cheers - Jem
Well, mate, worthless in so far anyway... as I am not trying to sell anything...
Thanks for the link. On my side I shared because I felt we owed the community as otherwise we wouldn't have discovered this amp, but of course our findings and impressions are just... that. And we are pleased with them, regardless the process, and it is a 6 Sigma Black Belt typing lol 🙂
Claude
Thanks for the link. On my side I shared because I felt we owed the community as otherwise we wouldn't have discovered this amp, but of course our findings and impressions are just... that. And we are pleased with them, regardless the process, and it is a 6 Sigma Black Belt typing lol 🙂
Claude