Amplifier build is here:
https://www.diyaudio.com/community/threads/finished-my-class-d-build-sounds-amazing.401362/
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Very happy with the sound of the amp, but I wanted to see if a positive impact could be made with OP-AMP changes.
Supplied with the zero zone TPA3255 boards I used are the JRC 5532DD OP-AMPS. Despite being nothing special they are a great match for the amplifier boards. Detail and separation are fantastic, I was quite happy with them.
After posting here and doing a bit of reading I decided to try the Texas Instruments OPA1656. Quite well regarded and made by TI who also make the 3255 chip contained in the amp boards. I was expecting good things.
First kick in the teeth was the eBay seller, or rather the packaging. Just a thin plastic sandwich bag. Inevitably one of the pair arrived with half its legs smashed off! The seller refused to replace, only refund. So I bought a replacement from another seller. Same awful packaging, this time bent legs which I carefully straightened.
They lasted 20 minutes in my system before the JRC's went back in. They sounded like pressing a loudness button with low and high end frequencies being boosted leaving the midrange (and thus a lot of detail) muffled and drowning. Soundstage was ruined, with the system now sounding like I had draped a duvet Infront of the speaker's .
Next up Burson Audio 'Vivid'
The first nice thing is the packaging. Nice and safe, no bent of missing legs. Off to a good start over the 1656!
These are quite large both in footprint and height. Not a problem on my boards but it could be for some.
Initial thoughts, bass was the first thing I noticed. I run my system with a pair of wharfedale Diamond 9.1's, which are fantastic speakers in my opinion, but somewhat lacking in the bass department. That said I usually listen at low volumes and I have spent many hours enjoying my system how it was.
I wasn't sure on the increase in bass that the Burson Vivids created at first. But continued testing. All of the detail and separation this system did so well was still present with an unexpected added bonus once in a blue moon.... the odd twang of a guitar at the end of a riff during Fleetwood Macs Rumours (SACD) would really pop and travel. Almost like in a surround system. The FOO FIGHTERS greatest hits provided no real changes over the JRC's apart from the previously mentioned increase in bass which after briefly swapping back to the JRC's and playing the same song again, I must say was now proving to be an improvement.
Now a volume increase to medium levels and some Bonobo - Fragments (24bit). A very atmospheric album with lots of little details like triangle twangs and sparkles. The Bursons did well here. Thankfully they left the soundstage alone just adding a touch of bass and the odd sparkle. I found myself waiting for these sparkly almost surround sound like moments. Nice.
After a couple of hours the increased bass was now a feature that I enjoy and having swapped back and to the JRC's a few times now, I need in my life.
For anyone who hasn't swapped around OP-AMPS before, we are not talking huge changes here. If I had to put a figure on it, somewhere between 5 & 10% (certainly with the opamps I used) subtle but notible.
In short I rate the Bursons, they will be staying in.
https://www.diyaudio.com/community/threads/finished-my-class-d-build-sounds-amazing.401362/
-----------------------
Very happy with the sound of the amp, but I wanted to see if a positive impact could be made with OP-AMP changes.
Supplied with the zero zone TPA3255 boards I used are the JRC 5532DD OP-AMPS. Despite being nothing special they are a great match for the amplifier boards. Detail and separation are fantastic, I was quite happy with them.
After posting here and doing a bit of reading I decided to try the Texas Instruments OPA1656. Quite well regarded and made by TI who also make the 3255 chip contained in the amp boards. I was expecting good things.
First kick in the teeth was the eBay seller, or rather the packaging. Just a thin plastic sandwich bag. Inevitably one of the pair arrived with half its legs smashed off! The seller refused to replace, only refund. So I bought a replacement from another seller. Same awful packaging, this time bent legs which I carefully straightened.
They lasted 20 minutes in my system before the JRC's went back in. They sounded like pressing a loudness button with low and high end frequencies being boosted leaving the midrange (and thus a lot of detail) muffled and drowning. Soundstage was ruined, with the system now sounding like I had draped a duvet Infront of the speaker's .
Next up Burson Audio 'Vivid'
The first nice thing is the packaging. Nice and safe, no bent of missing legs. Off to a good start over the 1656!
These are quite large both in footprint and height. Not a problem on my boards but it could be for some.
Initial thoughts, bass was the first thing I noticed. I run my system with a pair of wharfedale Diamond 9.1's, which are fantastic speakers in my opinion, but somewhat lacking in the bass department. That said I usually listen at low volumes and I have spent many hours enjoying my system how it was.
I wasn't sure on the increase in bass that the Burson Vivids created at first. But continued testing. All of the detail and separation this system did so well was still present with an unexpected added bonus once in a blue moon.... the odd twang of a guitar at the end of a riff during Fleetwood Macs Rumours (SACD) would really pop and travel. Almost like in a surround system. The FOO FIGHTERS greatest hits provided no real changes over the JRC's apart from the previously mentioned increase in bass which after briefly swapping back to the JRC's and playing the same song again, I must say was now proving to be an improvement.
Now a volume increase to medium levels and some Bonobo - Fragments (24bit). A very atmospheric album with lots of little details like triangle twangs and sparkles. The Bursons did well here. Thankfully they left the soundstage alone just adding a touch of bass and the odd sparkle. I found myself waiting for these sparkly almost surround sound like moments. Nice.
After a couple of hours the increased bass was now a feature that I enjoy and having swapped back and to the JRC's a few times now, I need in my life.
For anyone who hasn't swapped around OP-AMPS before, we are not talking huge changes here. If I had to put a figure on it, somewhere between 5 & 10% (certainly with the opamps I used) subtle but notible.
In short I rate the Bursons, they will be staying in.
Sounds like the eBay offering might be a fake or a remarked part (something like a 1458 opamp).
Another possibility is that wide bandwidth opamps can have stability issues in some circuits, particularly if supply decoupling is not optimised. There is a lot of HF flying around in a Class D amp.
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
Another possibility is that wide bandwidth opamps can have stability issues in some circuits, particularly if supply decoupling is not optimised. There is a lot of HF flying around in a Class D amp.
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
Hi, I have several JRC 5532 and others from TI like OPA1642, 1656, 1692..etc. With my DACs, the 1656 and 1692 sound with more depth in the image, more fluidity and definition. Same in a TPA3255 amp.
Although the JRC 5532 is a very good OP, the result can be different from one circuit to another, also the chain used.
My 2 cents !!
Although the JRC 5532 is a very good OP, the result can be different from one circuit to another, also the chain used.
My 2 cents !!
The 5532 is good device in pure analogue circuitry but there was often talked about suspicions years ago that when used for example after a DAC (such as I/V conversion) that the HF hash that is inevitably present at the inputs could cause non linearities and distortions as the input transistors and also diodes at the input tried to demodulate the HF. I always found FET opamps better for those applications, possibly because they are immune to that effect. Its something you can't easily pin down, just subjectively they were better.
It's a quirk of eBay: If a seller refunds you cannot leave negative feedback.
Therefore sellers invariably refund even when you explicitly ask for a replacement.
If you are otherwise happy with the seller, accept the refund & reorder.
You'll be very lucky to get any genuine semiconductors off eBay these days, always buy from reputable suppliers. Sending a FET input opamp (OPA1656) in anything but proper anti-static packaging is an immediate red-flag. Static will degrade or even destroy FET devices very easily indeed in ordinary plastic packaging.
When changing opamps you have to be aware of the various decoupling requirements of each chip - without the correct decoupling a chip may completely mishave and distort, and without a fast 'scope you may not realize its oscillating at VHF frequencies...
When changing opamps you have to be aware of the various decoupling requirements of each chip - without the correct decoupling a chip may completely mishave and distort, and without a fast 'scope you may not realize its oscillating at VHF frequencies...
Opamps work in feedback circuits where the gain is determined by the feedback network, not the opamp, so your impression that the Burson's changed the bass level are illusory, expectation bias was at work. Variation in bass gain due to realistic differences in opamps would be limited to a few thousandths of a dB between say a device with a low open-loop gain of 50,000 compared to one with much higher open-loop gain (1,000,000+)
Very happy with the sound of LT1819 dual opamps as the output buffer in my MSB discrete r2r dac. ( they come also LT1818 single)
https://www.analog.com/media/en/technical-documentation/data-sheets/18189fb.pdf
Cheers George
I read this post ages ago, but only now do I have time to chime in 
. I want to give my own impression of swapping op-amps with the TPA3255.
My amp is the well-known, budget-killer Aiyima A07 powered by a 32V/5A PSU, and the music source is through a DAC connected to my PC. Originally, the amp came with a pair of dodgy NE5532s, and later on I learned you can swap them out for something "better".
Internet research shows that people just love the combination of OPA1656 + TPA3255, so naturally, I used 1656s too. Beware, though, the Chinese sellers will not hesitate to package these fragile components and their sockets in something thinner than an envelope. Luckily, mine arrived almost intact except for the bent pins. Crude A/B testing shows that while there's no night-and-day difference, the OPA did improve definition and clarity. There's less "boom" in mid-bass and bass frequencies, making for a more balanced sound. Consequently, it has stayed in my amp ever since.
Not long after that, Burson Audio asked me to review their Burson SS V6 Vivid op-amps (so this is a semi-sponsored review. Also, it's 3 months late; sorry to the folks at Burson Audio). The well-protected package arrived at my door 2 months later, and I began auditioning them immediately.
The first thing that stood out for me, literally, is how gigantic they (op-amps) are, which makes them very troublesome in my case. The Aiyima's op-amp section has practically no clearance and, even worse, is surrounded by caps. NE5532s and OPA1656s have no trouble fitting in, but the Bursons' legs can't even reach down into the socket. I had to resort to stacking 2 DIP-8 sockets on top of each other, putting the Bursons on top, and then placing them into the amp. This also means the Aiyima has no top cover, with the op-amps sticking out like 2 sore thumbs. I call them "Red Chimneys"
Now for the SQ. I was actually surprised at how little change there is, going from 1656 to Vivid. Most aspects remain unchanged, even after a considerable burn-in duration. The only noticeable change is in some instruments and voices (essentially mid-high frequencies, I assume). The former, especially with piano notes, become more pronounced and "echo-y" (if it makes any sense) than before, which I appreciated. As for the latter, voices become more mellow and realistic, adding that "singer's literally in front of you" feeling by a tiny bit. Overall, these are positive changes that I like.
To conclude, are the Bursons worth the $145 asking price, or is the op-amp adventure even worth beginning? It depends. If you have a decent setup in all other aspects, would like to squeeze out a bit more sound magic, and have the cash to spare, go ahead. If there's one thing I can give, it is that the Bursons have great craftsmanship behind them and feel like a quality product. In other cases, maybe not. At best, it's gonna be a 10-15% improvement, while repositioning your speakers for free or treating your room can have a much bigger impact if you don't have an acoustically stellar listening room.
Thank you to OP for your personal review and Burson Audio for your review samples, I enjoyed using them. I hope the DIYAudio audience find this post useful in some regard.
. I want to give my own impression of swapping op-amps with the TPA3255.My amp is the well-known, budget-killer Aiyima A07 powered by a 32V/5A PSU, and the music source is through a DAC connected to my PC. Originally, the amp came with a pair of dodgy NE5532s, and later on I learned you can swap them out for something "better".
Internet research shows that people just love the combination of OPA1656 + TPA3255, so naturally, I used 1656s too. Beware, though, the Chinese sellers will not hesitate to package these fragile components and their sockets in something thinner than an envelope. Luckily, mine arrived almost intact except for the bent pins. Crude A/B testing shows that while there's no night-and-day difference, the OPA did improve definition and clarity. There's less "boom" in mid-bass and bass frequencies, making for a more balanced sound. Consequently, it has stayed in my amp ever since.
Not long after that, Burson Audio asked me to review their Burson SS V6 Vivid op-amps (so this is a semi-sponsored review. Also, it's 3 months late; sorry to the folks at Burson Audio
). The well-protected package arrived at my door 2 months later, and I began auditioning them immediately.The first thing that stood out for me, literally, is how gigantic they (op-amps) are, which makes them very troublesome in my case. The Aiyima's op-amp section has practically no clearance and, even worse, is surrounded by caps. NE5532s and OPA1656s have no trouble fitting in, but the Bursons' legs can't even reach down into the socket. I had to resort to stacking 2 DIP-8 sockets on top of each other, putting the Bursons on top, and then placing them into the amp. This also means the Aiyima has no top cover, with the op-amps sticking out like 2 sore thumbs. I call them "Red Chimneys"
Now for the SQ. I was actually surprised at how little change there is, going from 1656 to Vivid. Most aspects remain unchanged, even after a considerable burn-in duration. The only noticeable change is in some instruments and voices (essentially mid-high frequencies, I assume). The former, especially with piano notes, become more pronounced and "echo-y" (if it makes any sense) than before, which I appreciated. As for the latter, voices become more mellow and realistic, adding that "singer's literally in front of you" feeling by a tiny bit. Overall, these are positive changes that I like.
To conclude, are the Bursons worth the $145 asking price, or is the op-amp adventure even worth beginning? It depends. If you have a decent setup in all other aspects, would like to squeeze out a bit more sound magic, and have the cash to spare, go ahead. If there's one thing I can give, it is that the Bursons have great craftsmanship behind them and feel like a quality product. In other cases, maybe not. At best, it's gonna be a 10-15% improvement, while repositioning your speakers for free or treating your room can have a much bigger impact if you don't have an acoustically stellar listening room
.Thank you to OP for your personal review and Burson Audio for your review samples, I enjoyed using them. I hope the DIYAudio audience find this post useful in some regard.
OPA1656's from eBay? Little chance they were genuine I'm afraid. Did they come in anti-static packaging? If not they could be damaged. Even the Burson's don't come with anti-static packaging which is shameful really.
Suggest you get some genuine NE5532's while you still can and try those too. BTW what was dodgy about the original NE5532's?
Remember most semiconductors not from a reputable seller these days are counterfeit - the rogue sellers undercut the genuine ones on eBay alas, eBay doesn't seem to care.
And note that just rolling opamps at random is asking for issues - different opamps have different decoupling and stability requirements - so you may have devices oscillating at RF without even realizing...
Suggest you get some genuine NE5532's while you still can and try those too. BTW what was dodgy about the original NE5532's?
Remember most semiconductors not from a reputable seller these days are counterfeit - the rogue sellers undercut the genuine ones on eBay alas, eBay doesn't seem to care.
And note that just rolling opamps at random is asking for issues - different opamps have different decoupling and stability requirements - so you may have devices oscillating at RF without even realizing...
There's another reason for the purchase: I was sorta kinda hoping the fakes would leave SOP-8 designs alone for the most part. Ah well.
There's no anti-static packaging for both, unfortunately. And "damaged", well, the 1656s received some physical damage even...
It's been ages since I looked at them, but the lettering's not clear, the top texture feels off, and no mfg location's stamped on the bottom. My educated guess is that it's a TL072.
Honestly, I'm not aware of those compatibility issues - it would be fun if all the "improvements" turned out to be ear-pleasing oscillation. Strangely enough, so far in my research, I've found only one person who likes the stock op-amp and suggests that the designer "did a decent job with the circuit design".
Hi Mark,
I did a bit more research about my audio amplifier (Aiyima A07 with TPA3255) and came across this diagram for the op-amp input section by a Japanese blogger:
Karlsonate.
I did a bit more research about my audio amplifier (Aiyima A07 with TPA3255) and came across this diagram for the op-amp input section by a Japanese blogger:
I know next to nothing about circuit design, but I'm curious to know whether anything's off with this particular circuit and (possibly) how to improve it.
Karlsonate.
Well its seems to have good decoupling and probably won't have too many issues with swapping opamps.
Its volume section is fairly high impedance, changing the volume pot and R6 to 10k would reduce noise somewhat.
I haven't been able to source genuine LM4562s for now, but I hope to test them out soon.
Ok. Thanks for confirming. I will try them out in the custom-cased A07 and the factory A04 I also have. The factory A04 seems to have a little better midrange than the factory A07. From reading here, the 4562 cleans up the midrange freq. of the 07. We'll see as I ordered a pair for each unit to have a listen.
https://www.mouser.com/ProductDetai...MI9MaLqN6ChAMVakh_AB1HMg35EAAYASAAEgJn5fD_BwE
https://www.mouser.com/ProductDetai...MI9MaLqN6ChAMVakh_AB1HMg35EAAYASAAEgJn5fD_BwE
I tried MUSES02 from JRC and Burr Browns OPA2604 & OPA2134 and they don't sound as great as the LM4562 on my Fosi Audio ZA3s driving ATC SCM19 loudspeakers. How great are the LM4562s? A sweet midrange that is detailed with good spatial separation of instruments forming a vivid soundstage. For Subwoofer output, I used BB OPA2134 instead as LM4562 is not as punchy in the low-end. I am most willing to try the Sparkos SS3602 but they are costly.
I personally would NEVER buy any opamps off eBay---only source from Mouser, DigiKey, or another well-respected supplier.
Secondly, the first rule of op amp swapping is to eliminate any possibility of the device under test to oscillate. 100nF X7R caps across the +/- rails (pins 4 to 8), and 22pF COG caps across the feedback resistors (pins 1 to 2 and 6 to 7). This will limit the bandwidth to ~ 200 KHz---plenty enough for audio use and will usually eliminate any tendency of the DOT to oscillate. High quality machine sockets (MillMax) are also a must.
Secondly, the first rule of op amp swapping is to eliminate any possibility of the device under test to oscillate. 100nF X7R caps across the +/- rails (pins 4 to 8), and 22pF COG caps across the feedback resistors (pins 1 to 2 and 6 to 7). This will limit the bandwidth to ~ 200 KHz---plenty enough for audio use and will usually eliminate any tendency of the DOT to oscillate. High quality machine sockets (MillMax) are also a must.