• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

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

levimax

Major Contributor
Joined
Dec 28, 2018
Messages
2,348
Likes
3,462
Location
San Diego
I tend to agree but then again AIYIMA offers an "upgrade" opamp version of the A07 on their website. Do you think they tweak the circuitry for the "upgrade" opamp? I doubt it. Do they just do this for the uninformed?
They don't need to do anything as confirmation bias will make the upgraded op amp sound better to most people. Most if not all the differences would disappear if the comparison was done blind and level matched.
 

Lräk

Member
Joined
Jul 7, 2022
Messages
73
Likes
87
Location
Santa Clara, CA
I don't understand this opamp rolling. To my knowledge the circuit around the opamp needs to be designed specificly for the opamp used. Just because it fits mechanically and has the same pinout doesn't mean it fits the electric circuit i sits in. People don't go around 'rolling' different to-3 trannies in their amps, do they?
Nope. These designs have just been copied year after year. The NE5532 is a very old op amp. The fact that I could find at least 2 op amps from ADI that easily worked shows how easy it would be to try different ones. I actually thought the ADI chips did sound better.
 

ToMyr

Member
Joined
Jul 29, 2023
Messages
5
Likes
1
Nope. These designs have just been copied year after year. The NE5532 is a very old op amp. The fact that I could find at least 2 op amps from ADI that easily worked shows how easy it would be to try different ones. I actually thought the ADI chips did sound better.
people tend to like tweaks that turns something neutral into not neutral, and especially if they tweak it themselves. There is nothing wrong with the 5532, and there is ofc possible that a pin matching substitute can sound better/better in the ears of the tweaker. Never the less: an opamp must have the circuit around optimized/adapted for it. It is possible to design the circuit so that it is less picky about what opamp is used, but that again means you're not getting the best out of it.
 

375HP2482

Active Member
Joined
Jan 13, 2020
Messages
165
Likes
176
Considering the large amounts of negative feedback employed in the low-gain circuitry using the NE5532, the best one can hope for is an opamp with a lower noise figure, which would lower the noise maybe one dB or so -- a difference likely below perception.

As an aside, back in the sound reinforcement days of the early 70s we were making our own mixing consoles using mainly LM747s (dual 741s). We would have killed for something like the NE5532.
 

LtMandella

Member
Joined
Jan 13, 2021
Messages
67
Likes
44
Location
Las Vegas
I bought two A07s, one to experiment with and one to listen to (and maybe eventually I will try bi-amping).

I own multiple preamps (Transcendent Grounded Grid, Hafler DH-101 x 2), Musical Fidelity preamp out from M1Clic, Musical Fideltiy preamp out from A1-2008, FIIO headphone out, etc, etc, etc.

Would there be any sonic advantage to bypassing the "preamp/input buffer stage/volume control" of the A07 and use my other preamps for line level gain and volume control, and the A07 just for power? Due to the A07 having only one input I am now always using external preamp so I juggle two volume controls.

If there would be a potential sonic improvement, what would be involved in a bypass effort?

Maybe just short the volume control?
 
OP
pma

pma

Major Contributor
Joined
Feb 23, 2019
Messages
4,591
Likes
10,727
Location
Prague
You might get a bit lower overall noise, however I do not think you will get any "improvement" in perceived sound that could be demonstrated in a DBT test.
 

LtMandella

Member
Joined
Jan 13, 2021
Messages
67
Likes
44
Location
Las Vegas
The simplest way is to set A07 volume control to maximum and control the volume with the connected preamplifier.
I was thinking that would result in too much gain but worth a try.
 

LtMandella

Member
Joined
Jan 13, 2021
Messages
67
Likes
44
Location
Las Vegas
You might get a bit lower overall noise, however I do not think you will get any "improvement" in perceived sound that could be demonstrated in a DBT test.
oh well, another dumb idea of mine to go in the circular file ;)

But perhaps there is a flaw - or at least limitation - of the logic of DBT. It is quite possible that any one change might not improve distortion enough to be audible by itself in a DBT. So one could eschew multiple different changes in the presumption that any one change might not be audible. But couldn't they accumulate improvements? Such that eventually individual - and perhaps inaudible - improvements accumulate to the point a DBT would succeed in identifying a group of improvements.
But you would never get to that benefit if you bypass individual improvements in the presumption that each one on it's own would likely not be audible.
 
Last edited:

Zek

Major Contributor
Joined
Feb 17, 2018
Messages
1,582
Likes
2,146
I was thinking that would result in too much gain but worth a try.
Or maybe you should set the A07 volume to the loudest you listen to (and a little more than that), then adjust the volume level on the preamplifier.
 

LtMandella

Member
Joined
Jan 13, 2021
Messages
67
Likes
44
Location
Las Vegas
Or maybe you should set the A07 volume to the loudest you listen to (and a little more than that), then adjust the volume level on the preamplifier.
Yeah finding the sweet spot between the two is what I have been trying to do. Kind of a pain when switching sources with different output levels and no remotes anywhere :(
 
Top Bottom