Sometimes I wonder if this evilish sound addiction, after spending countless hours reading, thinking, testing, playing and modding makes any sane sense. Maybe some healthier habit, one that involves a little bit less obsession and a little more excercise would be great. But somehow I am back here🙂
Hours you spent are always a reference for the feasibility to finish a project. The less it takes the easier it is to finish. And that is important at least for me. Unfinished projects are a waste of effort time money and resources.
Also, and out of experience, whenever you do rework there is a chance to loose the board, which sucks big time coz you have to start from scratch ( yeah, who cares about $50 cost after you worked on the board for many hours. If you do rework, accept up front the possibility of loosing there board.
As an engineer I have a tendency to calculate all costs. I work in IT , but I design as a side business buletooth lens focus control systems for digital cameras. Even if you choose to ignore the cost of the hours, they are a cost. I do it quite often ignore the time.
But, oh well, let's go obsession crazy bananas and mod the sucker. i have some opamp and soldering supplies on the way 🙂
Francis
Hours you spent are always a reference for the feasibility to finish a project. The less it takes the easier it is to finish. And that is important at least for me. Unfinished projects are a waste of effort time money and resources.
Also, and out of experience, whenever you do rework there is a chance to loose the board, which sucks big time coz you have to start from scratch ( yeah, who cares about $50 cost after you worked on the board for many hours. If you do rework, accept up front the possibility of loosing there board.
As an engineer I have a tendency to calculate all costs. I work in IT , but I design as a side business buletooth lens focus control systems for digital cameras. Even if you choose to ignore the cost of the hours, they are a cost. I do it quite often ignore the time.
But, oh well, let's go obsession crazy bananas and mod the sucker. i have some opamp and soldering supplies on the way 🙂
Francis
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Hi Claude, per your post:
1) BTL common mode
2) Existing Epcos MKP caps on output filter are 0.68uF x 2 for left and right channels
3) I measured stock toroidal inductors at 12.5uH. Some nice Coilcrafts in 10uH or 15uH might work well depending on impedance vs. frequency between 10kHz -20kHz. Use TI’s filter calculation tool I previously mentioned in this thread. The Coilcrafts have a higher max. current rating for slightly lower distortion.
A good op amp to roll is the OPA1656 since you are familiar with those already. You’ll need some DIP8 adapters to mount them.
Touch up the solder joints for all components in the signal path and use your choice of wire to connect the amplifier PCB outputs and the speaker binding posts.
As for a good Mean Well SMPS, I chose the LRS-200-36 SMPS and dialed down the output voltage to 30V DC.
Many thanks Rich, spot on as ever 🙂
Thanks for confirming my assumptions so at least I haven't lost to much time on that.
Found meanwhile that Load factor was just an automatic field to help their calculation with equivalent simplified model - nothing to worry about.
Have quite a few DIP8 boards ready to go from previous project, so that I will have only to rebuild the one he likes most as he will keep then (and I will keep my flavour box 🙂
Enjoy music
Claude
Thanks for confirming my assumptions so at least I haven't lost to much time on that.
Found meanwhile that Load factor was just an automatic field to help their calculation with equivalent simplified model - nothing to worry about.
Have quite a few DIP8 boards ready to go from previous project, so that I will have only to rebuild the one he likes most as he will keep then (and I will keep my flavour box 🙂
Enjoy music
Claude
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Hi amigos,
Before I start, I would like to thank my friend DrMordor for his great work! you Rock Bro )
I have finally finished my last two projects) The idea is to test a high-end TPA32XX with PFFB and top quality components VS a Double mono Hypex Ncore NC250 whose reputation and measures are well established.
We were all amazed by the performances of the little Aiyima and as far as I'm concerned by the BRZHIFI as well. So I could easily compare these two amps with my new high end TPA32XX. On the other hand, my test is based on a subjective listening experience. But the measurements and THD of each amp are given on the respective websites of 360 Customs and Hypex.
Setup :
Speakers : 2.5Way High end Floor Speakers, Ribbon tweeter, 100W RMS / 8 ohms (about $2500 made in France)
DAC (options) : Double AK4497 + Quad Sabre DAC (V30)
Playlist : HD Audio Stream, Jazz / Classical / World Music.
Audio Player : LG V30 / APTX HD enabled
What do we have in the box?
Amp 1 @ left : TPA3251 based / inspired on 360 Customs design / TI. ( PFFB enabled , Main caps : Panasonic FC / Buffer caps : Elna Silmic II, Output filter : Wima, Handcraft Inductors with RM8 N87 Ferrite, OPA1602).
PSU Board : Handcrafted SMPS PSU (400W, TDK Epcos, EDT34 Core, LLC..)
Amp 2 @ right : Hypex double Mono Ncore NC250MP (see Hypex Datasheet : https://www.hypex.nl/documenten/download/916)
Both Amplifier are made with top quality materials (cables, RCA plugs etc). I also included RFI Blockers (tube type) that I clamped in all inputs / outputs (PSU / Line in / Speakers Output)...
Enclosures are made in Aluminium for the front and back panels and anti-scratch steel for the Top and Bottom covers.
What Can I say aftter a 10H listening test ?
Both Amplifier perform very very well but so differently )
What immediately jumped to my ears when I listened to this TPA3251 at the first time, is a sudden sensation on the opening of the sound compared to my Aiyima / BRZHIFI. The Soundstage has been gleefully improved : So much so that I felt like I was rediscovering all my HD Audio Playlist. The power of the amp is also revised upwards, I would say about 25% / 30% ! It is evident that the quality components have an obvious impact on the listening and the power of the amp. The treble and mids are really better, it's as if the voices were detached from the instruments on my speakers. The bass is also more forward and more frank, they are neither too invasive nor too erased.
I really love what I listen to !
Let's move now on to the Hypex Ncore. What immediately surprised me VS the TPA3251 is the listening experience, especially for the bass.
We feel that the Hypex Ncore have a greater dynamic, it's really obvious at first listen. However, I found the soundstage more interesting on the side of the TPA3251. The hypex is however more powerful than the TPA3251 and therefore we have a more significant power reserve on the Ncore side (I'm talking about the NC250MP). Regarding the rest of the register, the Mediums and trebles are sublime and the timbers are also surprising. Concerning a slightly more global listening and, on different registers = Jazz, classical music, Worldmusic, both amplifiers are really neck and neck. I find the TPA3251 more neutral and the Hypex a little more colorful.
Verdict (Plus and cons) :
We have here two very good Class D amps. Both amplifiers will be suitable for HIFI listening and will cover a multitude of registers with enough ease. If you need power and finesse, the Hypex is better suited. If you listen to music at a more moderate volume, the TPA3251 based on a good design, is perfect.
Two small faults to note on both sides: : Pop sound only when turning OFF the TPA3251 and I found the Hypex a bit less silent than the TPA3251.
Regarding the price ... a high-end TPA32XX with a great PSU is cheaper than a double Mono Hypex NC250MP.
I love these two amps and frankly, at this point: I do not know which one I would keep .... One thing is certain: these are by far the best Class D I have listened to.
I hope this review can help you in your future choices and considerations.
Danny
Pictures :
Before I start, I would like to thank my friend DrMordor for his great work! you Rock Bro )
I have finally finished my last two projects) The idea is to test a high-end TPA32XX with PFFB and top quality components VS a Double mono Hypex Ncore NC250 whose reputation and measures are well established.
We were all amazed by the performances of the little Aiyima and as far as I'm concerned by the BRZHIFI as well. So I could easily compare these two amps with my new high end TPA32XX. On the other hand, my test is based on a subjective listening experience. But the measurements and THD of each amp are given on the respective websites of 360 Customs and Hypex.
Setup :
Speakers : 2.5Way High end Floor Speakers, Ribbon tweeter, 100W RMS / 8 ohms (about $2500 made in France)
DAC (options) : Double AK4497 + Quad Sabre DAC (V30)
Playlist : HD Audio Stream, Jazz / Classical / World Music.
Audio Player : LG V30 / APTX HD enabled
What do we have in the box?
Amp 1 @ left : TPA3251 based / inspired on 360 Customs design / TI. ( PFFB enabled , Main caps : Panasonic FC / Buffer caps : Elna Silmic II, Output filter : Wima, Handcraft Inductors with RM8 N87 Ferrite, OPA1602).
PSU Board : Handcrafted SMPS PSU (400W, TDK Epcos, EDT34 Core, LLC..)
Amp 2 @ right : Hypex double Mono Ncore NC250MP (see Hypex Datasheet : https://www.hypex.nl/documenten/download/916)
Both Amplifier are made with top quality materials (cables, RCA plugs etc). I also included RFI Blockers (tube type) that I clamped in all inputs / outputs (PSU / Line in / Speakers Output)...
Enclosures are made in Aluminium for the front and back panels and anti-scratch steel for the Top and Bottom covers.
What Can I say aftter a 10H listening test ?
Both Amplifier perform very very well but so differently )
What immediately jumped to my ears when I listened to this TPA3251 at the first time, is a sudden sensation on the opening of the sound compared to my Aiyima / BRZHIFI. The Soundstage has been gleefully improved : So much so that I felt like I was rediscovering all my HD Audio Playlist. The power of the amp is also revised upwards, I would say about 25% / 30% ! It is evident that the quality components have an obvious impact on the listening and the power of the amp. The treble and mids are really better, it's as if the voices were detached from the instruments on my speakers. The bass is also more forward and more frank, they are neither too invasive nor too erased.
I really love what I listen to !
Let's move now on to the Hypex Ncore. What immediately surprised me VS the TPA3251 is the listening experience, especially for the bass.
We feel that the Hypex Ncore have a greater dynamic, it's really obvious at first listen. However, I found the soundstage more interesting on the side of the TPA3251. The hypex is however more powerful than the TPA3251 and therefore we have a more significant power reserve on the Ncore side (I'm talking about the NC250MP). Regarding the rest of the register, the Mediums and trebles are sublime and the timbers are also surprising. Concerning a slightly more global listening and, on different registers = Jazz, classical music, Worldmusic, both amplifiers are really neck and neck. I find the TPA3251 more neutral and the Hypex a little more colorful.
Verdict (Plus and cons) :
We have here two very good Class D amps. Both amplifiers will be suitable for HIFI listening and will cover a multitude of registers with enough ease. If you need power and finesse, the Hypex is better suited. If you listen to music at a more moderate volume, the TPA3251 based on a good design, is perfect.
Two small faults to note on both sides: : Pop sound only when turning OFF the TPA3251 and I found the Hypex a bit less silent than the TPA3251.
Regarding the price ... a high-end TPA32XX with a great PSU is cheaper than a double Mono Hypex NC250MP.
I love these two amps and frankly, at this point: I do not know which one I would keep .... One thing is certain: these are by far the best Class D I have listened to.
I hope this review can help you in your future choices and considerations.
Danny
Pictures :
Hi Claude, I hope you are doing well ) Remind me where are you from please ? If you are looking for some TPA32XX or Ncore boards, send me a private message, I have some Class D boards at home.
Hi Danny,
I am North of Paris...
Thanks for the kind offer, but it is not really for me and my friend has just purchased 2 Aiyima, thanks to your recommandation. Ready to go or to be tweaked, easier and neatly packed. But who knows, if he wants to built on that, I keep that in mind.
Back to you, I am glad you found another improvement path that suits your ears, well done!
Ejoy music
Claude
I am North of Paris...
Thanks for the kind offer, but it is not really for me and my friend has just purchased 2 Aiyima, thanks to your recommandation. Ready to go or to be tweaked, easier and neatly packed. But who knows, if he wants to built on that, I keep that in mind.
Back to you, I am glad you found another improvement path that suits your ears, well done!
Ejoy music
Claude
Non, pas Parisien! Au Nord pas trop loin, enfin, pour l'instant... but you already asked that question! Too many projects, LOL!
Take care
Claude
Take care
Claude
I managed to put in the OPA627 as recommended by Rich (rhing). I feel they helped smooth the top and made the sound a bit fuller. I might look at changing the some of the caps, probably the 2 PSU as I am running 32v and they are rated 35v, and maybe the buffer/output.
LOL indeed forgot... sorry Claude ) J'étais convaincu que tu étais Canadien lol... je pense que les projets ont eu raison de ma mémoire 😀😀
Thinking output filter...
If that unit sounds as promising as stated here, we think of course about modding it and that would include the output coils.
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 teh 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...
So option 1 or 2? Any idea on your side, or experience?
Thanks as ever!
Claude (thinking out loud while the units are on their way 🙂
If that unit sounds as promising as stated here, we think of course about modding it and that would include the output coils.
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 teh 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...
So option 1 or 2? Any idea on your side, or experience?
Thanks as ever!
Claude (thinking out loud while the units are on their way 🙂
Thanks mate...
Well, know all that, I did the same for MY speakers and these are very different than Rich's, so you have to know what you are doing there as defo no copy paste nor same conclusions!
Rich optimised rightly for his speakers, say around 6R impedance in the 10-20kHz band, but my (friend's) speakers are around 10R in that band, so defo not the same.
So once optimised for these LS and taking into account existing real life quality components I end up with 2 options, hence my post, trying to find out if anyone had experimented with that. There is no bad option there on the paper, more real life experience in home environment and possibly emission problem with that very own unit.
Hmm, I realize perhaps a handfull of designers here went as far as to really determine the entire output filter caracteristics, not just replacing components with better ones with , say, similar value ranges around a filter that had been already designed, so not sure I won't have to answer that one myself.
Thanks anyway for your kind help
Claude
Well, know all that, I did the same for MY speakers and these are very different than Rich's, so you have to know what you are doing there as defo no copy paste nor same conclusions!
Rich optimised rightly for his speakers, say around 6R impedance in the 10-20kHz band, but my (friend's) speakers are around 10R in that band, so defo not the same.
So once optimised for these LS and taking into account existing real life quality components I end up with 2 options, hence my post, trying to find out if anyone had experimented with that. There is no bad option there on the paper, more real life experience in home environment and possibly emission problem with that very own unit.
Hmm, I realize perhaps a handfull of designers here went as far as to really determine the entire output filter caracteristics, not just replacing components with better ones with , say, similar value ranges around a filter that had been already designed, so not sure I won't have to answer that one myself.
Thanks anyway for your kind help
Claude
I have today Wurth 7443630700, Ferrocore HCI2114, nanocrystalline core, wait PCBs.
Attachments
Hi Danny,
Very interesting comparison.
I would be happy to submit to you, at some point, one of our TAS3251 boards (Neat Amp, other thread). I expect a similar level of performance to the TPA3251 implementation. I would be interesting to know how it compares to your reference set-up.
My parents don't live so far from you (69380 Dommartin), but I don't travel so often there. And during summer, they head to the south.
We may find a way 🙂 and I need to build two other boards.
JMF
Very interesting comparison.
I would be happy to submit to you, at some point, one of our TAS3251 boards (Neat Amp, other thread). I expect a similar level of performance to the TPA3251 implementation. I would be interesting to know how it compares to your reference set-up.
My parents don't live so far from you (69380 Dommartin), but I don't travel so often there. And during summer, they head to the south.
We may find a way 🙂 and I need to build two other boards.
JMF
When you get to see your parents : do not hesitate, you'll be welcome to test my amps.
TAS3251 is a TPA3251 + Internal Burr-Brown™ DAC with integrated DSP if I am not wrong. Would be interesting to listen )
You can send me a private message so we can discuss @ phone )
Yes, that's it. I designed the board using from beginning "best components" like Würth coils, Elna Silmic... no shortcuts compared to the TI EVM, and some good advices from proficient people like doctormord and AIM65.
Results are very promising, for a very compact setup with DSP ability (ideal for active speakers).
I will contact you when heading to my parents.
JMF
With pleasure. Looking forward to hear you.
I am working on my new DIY amp, double Mono based on Pascal modules.
They are expansive but read some great reviews about it.🙂