AIYIMA A07 TPA3255 Amplifier Measurements and Review - LM4562 (and OPA2134) option

[wave]

Please don't throw it away. I would be interested to send it to me (postage payed by me) to troubleshoot it and try to fix it.

 

[julbo]

Please don't throw it away. I would be interested to send it to me (postage payed by me) to troubleshoot it and try to fix it.

I'll pay you 25 50% of the AIYIMA A07 worth if you solve this and post it here, I'm serious

 

[wave]

Either way, I always like to share the results of repair attempts and modifications to electronic devices. But usually I do this on more technical forum.

It would be interesting since I already own a perfectly working unit, so I can compare them and get measurements from both trying to find what's wrong with the other one, even directly swap parts

 

[julbo]

Thank you . Yes we do expect for Topping PA5 to behave better (however not perfect) for the reason that a similar issue is pushed higher in the frequency axis. This is re Zout.

Talking about class D generally, even the best performers Purifi and Hypex are not free of high frequency nonlinearity issue (yes >20kHz distortion components, to be clear).

On Class D Amplifiers Measurements

Thank you, @DDF , to turn my attention to Jon Risch. I have googled some of his papers and also his posts on audioreview forum. He knows what he speaks about and he is one of those from whom I can still learn something. Thanks again! Glad to help @pma. I was one of those corporate engineers...

www.audiosciencereview.com

Talking about AIYIMA A07, it will end up in a dustbin soon. Though I use it only occasionally mostly for tests, and it has not operated more than a couple of hours summed, the right channel started to emit high frequency hiss noise time after time, without any special reason, even if nothing is connected to the input. What would one expect at $90, it has done its job on my test bench. Not recommended, by myself.

Was planning to use the A07 to drive a Directiva r1 build that runs a 27TBCD/GB-DXT tweeter. The impedance response is complex (~90deg phase) and fairly well behaved, maybe I'll be able to flatten the amp so hope is not lost


Courtesy of Heißmann-Acoustics:

 

[julbo]

I just managed to fry my Scarlet2i4 sound card with my newly arrived A07. One of the regulator ICs was smoked into oblivion. I think the mistake was moving the sound card USB cable from PC_1 to another PC_2 while the A07 was operating. I noticed a 14KHz interference that did not compute to anything w/o playback, I assumed it might seep from PC_1. I had Picoscope connected to PC_2. I checked any leaks to USB Gnd and scope probe Gnd and RCAs, seems isolated. A07 works OK, checking for any weird AC/DC injection into the RCA inputs revealed nothing, apart of a 40mVpp switching square wave @600KHz. It's the power switching freq, still I would have hoped for a quiet floating input. SMPS 48.6V no load. I should say workmanship looks good with this lovely little amp, build and soldering look solid

 

[winflex]

PMA - great review with extensive testing. The power supply is always the key ingredient and most expensive part of any given amp if seems. My question is have you tried using batteries? I understand there are limitations with that idea - charging challenges, etc. Seems like 3 - 12 volt deep cycle batteries in series for 36 volts could be interesting to try.

Funny you should mention this... I bought a 48V 10,000mAh E-Bike battery on Amazon for less than $190 shipped and built this little bi-amped portable box.

Installed better thermal paste under the heat sinks and removed the top covers from the amplifier enclosures to facilitate better cooling. When flipped on its side this box really benefits from natural convective cooling now

Sounds great & no more thermal shutdowns when playing at high volumes into low sensitivity speakers.

I installed some Speakon NL4 sockets in a pair of Paradigm Monitor 11 S7 tower speakers a buddy donated - Now the whole setup is portable and great for outdoor parties & such.

Current measurements indicate the battery should be good for 20 hours of high volume playback and 77 hours of standby.

 

[kostaaa]

After reading the whole forum carefully.... I feel disappointed that at the end Pawel (pma) doesn't recommend this amp.
I'm wondering, if it sounds any better than my Pioneer xv-dv 505 receiver with njm4558 amps (THD+N = 0.002%):

Schematic Diagram - Pioneer xv-dv505 Service Manual [Page 5]

Pioneer xv-dv505 Manual Online: Schematic Diagram. 2.1 DVDM ASSY(1/2) B 1/2F DVDM ASSY(1/2) (AWM7684) : The power supply is shown with the marked box. 1 2 Note : When ordering service parts, be sure to refer to ''EXPLODED VIEWS IC301 L6315ATXXTY (RAM) FRONT END IC 1 XV-DV505 2 3 and...

www.manualslib.com

https://www.semiee.com/file/EOL2/CADEKA-NJM4558.pdf

Right now I'm using it power Blue Sky EXO 2.1 (ver.1) monitors.... but I'm mostly interested, if it's suitable (impedance?) for Dali Spektor 1 or 2?
At some graphs here, I see very nice distribution of the harmonics.... (2nd dominant, than 3rd, 4th,...) that makes me think it should sound better than some others (Loxjie A30)?!
I want to listen music on desktop in an acoustically treated room.
Thanks!

 

[restorer-john]

Funny you should mention this... I bought a 48V 10,000mAh E-Bike battery on Amazon for less than $190 shipped and built this little bi-amped portable box.

Installed better thermal paste under the heat sinks and removed the top covers from the amplifier enclosures to facilitate better cooling. When flipped on its side this box really benefits from natural convective cooling now

Sounds great & no more thermal shutdowns when playing at high volumes into low sensitivity speakers.

I installed some Speakon NL4 sockets in a pair of Paradigm Monitor 11 S7 tower speakers a buddy donated - Now the whole setup is portable and great for outdoor parties & such.

Current measurements indicate the battery should be good for 20 hours of high volume playback and 77 hours of standby.

That looks great! Well done. I particularly like the blue/silver instrument grade casework.

 

[Midnight Audiophile]

After reading the whole forum carefully.... I feel disappointed that at the end Pawel (pma) doesn't recommend this amp.
I'm wondering, if it sounds any better than my Pioneer xv-dv 505 receiver with njm4558 amps (THD+N = 0.002%):

Schematic Diagram - Pioneer xv-dv505 Service Manual [Page 5]

Pioneer xv-dv505 Manual Online: Schematic Diagram. 2.1 DVDM ASSY(1/2) B 1/2F DVDM ASSY(1/2) (AWM7684) : The power supply is shown with the marked box. 1 2 Note : When ordering service parts, be sure to refer to ''EXPLODED VIEWS IC301 L6315ATXXTY (RAM) FRONT END IC 1 XV-DV505 2 3 and...

www.manualslib.com

https://www.semiee.com/file/EOL2/CADEKA-NJM4558.pdf

Right now I'm using it power Blue Sky EXO 2.1 (ver.1) monitors.... but I'm mostly interested, if it's suitable (impedance?) for Dali Spektor 1 or 2?
At some graphs here, I see very nice distribution of the harmonics.... (2nd dominant, than 3rd, 4th,...) that makes me think it should sound better than some others (Loxjie A30)?!
I want to listen music on desktop in an acoustically treated room.
Thanks!

I use an A07 with a Drok 48v, 10 amp adjustable power supply, and run Dali Spektor 2 speakers with it. I think it performs excellent. I run OPA1656 op amps just for the hell of it and I also have it ventilated by using a simple template I created:

 

[kostaaa]

Thank you very much for the reply, I ordered it a few days ago.... for only 55 euros (using some discounts and coupons from Aliexpress), shipping from Poland!
I hope it will not need ventilations with 24-27V..... but I will keep in mind because in Greece is hot now. Thanks for sharing the template!

 

[Schlippwhip68]

It seems paying a few more dollars for LM4562 op amp instead of NE5532 doesn't really make much sense.
LM4562 may be slightly better, but the difference is not audible.

No offence but the difference between these two op amps is very much distinguishable. I am a little baffled as to why so many people think that rolling op amps is a waste of time, in my experience is most certainly is a beneficial practice. Sound character can even be slightly different on the same op amp but different manufacture. For example I have a few NE5532 opa from Philips that actually do sound slightly superior to the Texas Instruments version and again it's noticeable when using the A07. I also believe in 'complimentary balance' which means having certain opa in one part of the chain and another type in another part of the chain. I have done this with great results using the Aiyima A07 and the Aiyima T6 Pro. I went through a few different opa in search of a satisfactory sound with either a complimentary balance or a pure line of one sort. In the end it was a complimentary balance between the BB opa2604 and the LM4562 that won the day. You see the opa2604 has quite a thick sound, easy to listen to, not bright or analytical in any way and the LM4562 leans in the opposite direction, not too much mind but enough to liven up the opa2604 and put some sparkle in there while the opa2064 beefs up the low end of the LM4562 quite nicely and the end result is a fuller rich and detailed sound. The LM4562 sitting in the A07 and the BB opa2604 sitting in the preamp output stage. I also used a pair of Mullards 5654 8100 valves instead of the Jan 5654 stock that came with the T6 pro which can be a little bright at the top end but the Mullards are like the opa2604, nice and thick sounding with a strong low end. Overall a very fine result in sound quality.

 

[Doodski]

No offence but these difference between these two op amps is very much distinguishable. I am a little baffled as to why so many people think that rolling op amps is a waste of time, in my experience is most certainly is a beneficial practice. Sound character can even be slightly different on the same op amp but different manufacture. For example I have a few NE5532 opa from Philips that actually do sound slightly superior to the Texas Instruments version and again it's noticeable when using the A07. I also believe in 'complimentary balance' which means having certain opa in one part of the chain and another type in another part of the chain. I have done this with great results using the Aiyima A07 and the Aiyima T6 Pro. I went through a few different opa in search of a satisfactory sound with either a complimentary balance or a pure line of one sort. In the end it was a complimentary balance between the BB opa2604 and the LM4562 that won the day. You see the opa2604 has quite a thick sound, easy to listen to, not bright or analytical in any way and the LM4562 leans in the opposite direction, not too much mind but enough to liven up the opa2604 and put some sparkle in there while the opa2064 beefs up the low end of the LM4562 quite nicely and the end result is a fuller rich and detailed sound. The LM4562 sitting in the A07 and the BB opa2604 sitting in the preamp output stage. Ialso used a pair of Mullards 5654 8100 valves instead of the Jan 5654 stock that came with the T6 pro which can be a little bright at the top end but the Mullards are like the opa2604, nice and thick sounding with a strong low end. Overall a very fine result in sound quality.

Most of the difference you hear if not all of it is due to the gain characteristics of each OP amp being different. In other words some are louder than others and that will trick you to thinking it sounds better. The frequency response of OP amps is so accurate and wide that for you to hear a difference you would need super human hearing which doesn't happen.

 

[Schlippwhip68]

Most of the difference you hear if not all of it is due to the gain characteristics of each OP amp being different. In other words some are louder than others and that will trick you to thinking it sounds better. The frequency response of OP amps is so accurate and wide that for you to hear a difference you would need super human hearing which doesn't happen.

Nope, it's definitely sound character and not volume increase either globally or sector even though I still agree with you in regards to gain.

 

[Tangband]

No offence but these difference between these two op amps is very much distinguishable. I am a little baffled as to why so many people think that rolling op amps is a waste of time, in my experience is most certainly is a beneficial practice. Sound character can even be slightly different on the same op amp but different manufacture. For example I have a few NE5532 opa from Philips that actually do sound slightly superior to the Texas Instruments version and again it's noticeable when using the A07. I also believe in 'complimentary balance' which means having certain opa in one part of the chain and another type in another part of the chain. I have done this with great results using the Aiyima A07 and the Aiyima T6 Pro. I went through a few different opa in search of a satisfactory sound with either a complimentary balance or a pure line of one sort. In the end it was a complimentary balance between the BB opa2604 and the LM4562 that won the day. You see the opa2604 has quite a thick sound, easy to listen to, not bright or analytical in any way and the LM4562 leans in the opposite direction, not too much mind but enough to liven up the opa2604 and put some sparkle in there while the opa2064 beefs up the low end of the LM4562 quite nicely and the end result is a fuller rich and detailed sound. The LM4562 sitting in the A07 and the BB opa2604 sitting in the preamp output stage. Ialso used a pair of Mullards 5654 8100 valves instead of the Jan 5654 stock that came with the T6 pro which can be a little bright at the top end but the Mullards are like the opa2604, nice and thick sounding with a strong low end. Overall a very fine result in sound quality.

Can agree on everything you wrote. There are clearly sounddifferences between opa2604 and lm4562. One can almost not find two more different sounding IC:s. The first one is sounding warm and innofensive, and the LM 4562 is cleaner and leaner. Both are musically better than ne5532, in my subjective opinion. The opa2604 is a fet opamp and 4562 is a bipolar based IC.

An interesting fact:
Linn products used opa2604 everywhere during the late ninethies including in the legendary CD12 , but changed to LM 4562 everywhere at 2007 when the klimax DS streamer came out. The different players sounded different. Now they seems to have changed again to opa1612 in many places - maybe a suggestion to try ? I have tried ne5532, opa2604, lm4562 and opa1612 and I prefered LM 4562 in both Aiyima a07 and the tpa3251-based Aiyima a04.

 

[Joe Smith]

Can agree on everything you wrote. There are clearly sounddifferences between opa2604 and lm4562. One can almost not find two more different sounding IC:s. The first one is sounding warm and innofensive, and the LM 4562 is cleaner and leaner. Both are musically better than ne5532, in my subjective opinion. The opa2604 is a fet opamp and 4562 is a bipolar based IC.

An interesting fact:
Linn products used opa2604 everywhere during the late ninethies including in the legendary CD12 , but changed to LM 4562 everywhere at 2007 when the klimax DS streamer came out. The different players sounded different. Now they seems to have changed again to opa1612 in many places - maybe a suggestion to try ? I have tried ne5532, opa2604, lm4562 and opa1612 and I prefered LM 4562 in both Aiyima a07 and the tpa3251-based Aiyima a04.

Tangband, do you have a link to a reputable sales site for the right type of LM4562's for the A07 or the A04 amps?

 

[Mal]

I have an Aiyima A07 attached to Wharfedale Diamond 9.0 speakers and they sound far too bright for any comfort. Are you suggesting that the amp might be amplifying high frequences by several DB in this context? I have tamed the sound to bearable levels using a Schiit Loki with high frequency knobs rotated anti-clockwise to max (!) But the sound still isn't great. I was going to change the speakers, but now you have me thinking it is mostly this amp at fault. Now I'm thinking of giving up on passive speakers completely. Companies might be more motivated to get things working if the speaker company can't blame the amp company and the amp company can't blame the speaker company. Also, I really like my KEF LSXs - there everything (speaker, amp, dac, EQ) is all in one box... there is only one company that has to shoulder all the blame (or praise...) How did KEF tame the Class D amps in their LSXs?

 

[pma]

I have an Aiyima A07 attached to Wharfedale Diamond 9.0 speakers and they sound far too bright for any comfort. Are you suggesting that the amp might be amplifying high frequences by several DB in this context?

Yes. And it does - as shown in several measurements with various speakers and with a dummy load.

 

[Schlippwhip68]

Can agree on everything you wrote. There are clearly sounddifferences between opa2604 and lm4562. One can almost not find two more different sounding IC:s. The first one is sounding warm and innofensive, and the LM 4562 is cleaner and leaner. Both are musically better than ne5532, in my subjective opinion. The opa2604 is a fet opamp and 4562 is a bipolar based IC.

An interesting fact:
Linn products used opa2604 everywhere during the late ninethies including in the legendary CD12 , but changed to LM 4562 everywhere at 2007 when the klimax DS streamer came out. The different players sounded different. Now they seems to have changed again to opa1612 in many places - maybe a suggestion to try ? I have tried ne5532, opa2604, lm4562 and opa1612 and I prefered LM 4562 in both Aiyima a07 and the tpa3251-based Aiyima a04.

I have my A04 equipped with a pair of Oracle 02 op amps which apparently have been torn down by an Ali express customer and found to be an modded opa1612. The do sound nice, quite a gentle fairly balanced clear sound but are a little light on the bass for my taste but they do shine in the vocals especially female and good highs. I really wanted that extra body in the low end though which why i used the opa2604 in my preamp, The Aiyima T6 Pro which also has been given a switch out from the jan5654 valves to the Mullard 5654 which are like the opa2604 in valve form so i have quite a thick sound in general coming from the T6 Pro meeting the LM4562 in the final stage with the A07, works really well my friend.

 

[Schlippwhip68]

I use an A07 with a Drok 48v, 10 amp adjustable power supply, and run Dali Spektor 2 speakers with it. I think it performs excellent. I run OPA1656 op amps just for the hell of it and I also have it ventilated by using a simple template I created:
View attachment 221182View attachment 221183

 

[Mal]

Yes. And it does - as shown in several measurements with various speakers and with a dummy load.

Do you think a Schiit Loki can fix the problems with the AO7? It seems fairly flat across most of the range. Can tweaking the high frequency knobs on the Loki provide a general fix for the A07? With my tweaking so far I'm feeling ambivalent. (Just had good session where I tweaked dialogue to "very acceptable" - but they were blokes with deep baritone's!) Note, although there is this high frequency problem, the audio has great definition - perhaps best I've ever heard. I suspect this is thanks to the Topping 10s DAC that feeds into the amp (?) But the Topping 10s has a reputation for being hard & glassy, could it be compounding high frequency problems with the amp & speaker? Could a Schiit Modi DAC and darker speakers (Dali/Q Acoustic?) work better with A07?