Is LM4562 good for DAC output?

[stef1777]

Hi Folk!

Is the LM4562 really good at DAC output use? Or its spec need a special design for best use?

For testing purpose, I installed this op-amp in different equipments. In pre-amplifier circuit, in buffer and filter with nice result. But I tried to use it in DAC output (LPF circuit) in 2 different equipments, and each time, I had a very bad sound.

The sound is very detailed but metallic and flat. If I replace it with an AD8620 or an OP627 or another op-amp as OPA2134, the sound is ok.

The last tried was inside a Tag AV32R. The circuit is designed for an OPA2134. It's at DAC output (AK4393), the next circuit in the chain is an CS3310. The op-amp output is directly connected to the input of the CS3310. PSU is 12,5v. I've enclosed the approximate schematic to this post. I've not traced all the circuit yet. Some values are missing and may be some component too. The equipments is curently in use and only worked with some picture I made.

Any idea ?

[singa]

Hi,
Let your ears be the final judge.Could it be the filter network
is not suitable for LM4562?Is the CS3310 "perfect" soundwise?

Cheers.

[stef1777]

I've made a list of the possibilities:

- filter network and sum not adapted (too high impedance)
- output from LM4562 not adapted with CS3310 input. In fact, the CS3310 have been replaced by a PGA2311A.
- PSU: on the LM4562 datasheet, they specify 47uF on the rail close to the chip. We "only" have 10uF in this circuit.
- PSU: 12v too low for optimum performance
- the op-amp itself -> sonic signature too chirurgical. As I tested the mod with a pair of Dynaudio Contour, each change is really easy to heard.

I don't think that the PCB can cause this. As you can see in the picture, its well done.

I replaced it with an AD8620. In this circuit and with the rest of my equipments, it's the best for me.

[martin clark]

Don't worry Stef, trust your ears. A few of us have had similar experience with the 4562 and its single derivative (LME47910) - all the notes but little of the expression.

Your list of possibilities looks good to me. I've experimented quite a lot with PSu/regulators, operating voltages and decoupling strategies and just couldn't get a compelling result from the 47910 in a CD player output stage. I'll try it elsewhere another time.

[stef1777]

Originally posted by martin clark all the notes but little of the expression.

Great sentence. I've the same thinking. You can count and place all instruments but each one is playing alone and not with the same tempo. C'est la cacophonie !

I installed it at the input stage of a modled Quad 405 and at input stage of an UcD180 with great result.

[MidiMaze]

Just give this a shot

http://midiserver.student.utwente.nl...0/minidisk.htm

[namcir]

hi steff i am a little confused with you
you have mentioned in another thread that lm4562 is the winner compared to other opamps when using the TAG with other people listening also is it the sapme you used since i think you havent ordered it before?
i also want to try LM4562 to my nad cdp now i'm using lm6172

[stef1777]

Originally posted by RICMAN
hi steff i am a little confused with you
you have mentioned in another thread that lm4562 is the winner compared to other opamps when using the TAG with other people listening also is it the sapme you used since i think you havent ordered it before?
i also want to try LM4562 to my nad cdp now i'm using lm6172

Yes, you're true. It was a big mistake or "wrote too fast".

In fact, I first tested the tag mods on a pair of small speaker with an old sono amplifier in stereo. The sound was apparently fine. The details added by the LM were impressive. But after, I tested it on my main install (with a big Dynaudio Contour). This system is very transparent and reveal all problem in sound as a magnifying glass. It was impossible to listen something more than 10 minutes.

I opened again the Tag and done again an op-amp swap session but this time on my main system.

The LM4562 stay the better op-amp for details, quality of bass and tone but the sound is too transparent. Too many details hide the music. Music became like a "cacophony" of different instrument. Each sound competing to be the first.

Used in surround mode, it was worst than in stereo. All this transparency made movie listening close to impossible. Dialog was completely hidden in background music and effect.

I installed the LM inside an UcD180 and in a QUAD 405 (input buffer) with success compared to others. The LM fit also fine in the output buffer of the Tag. I also installed a pair of LM4562 at DAC output of a DEQ2496 without problem.

But definitively not in the LPF at DAC output of the Tag.

I also tried the lm6172 in the Tag but preferred the AD8620. I was surprised because, I'm not a 8620 lover.

To end, I'll say that the LM4562 is a great op-amp but less "universal" that the OPA2134 or NE5532. Depending of the circuit or the others parts of the system, you can have the best or the worse. You should try.

.

[stef1777]

Originally posted by MidiMaze
Just give this a shot

http://midiserver.student.utwente.nl...0/minidisk.htm

I love the gameboy used as a spectrum analyser. ;-)

I'll do some FFT spectrum test by the end of the week.

.

[namcir]

as i am searching the web about lm4562 reading comments by others made me think that 4562 is a good opamp in other circuits like in tone controls, preamp, buffer, phono preamp but not in some circuits like I/V, cd output stage, DAC output...IMHO?

steff you may try THS4032 maybe it suits your tag and let us know the results i used this in my philips cd output stage with good results just dont use it in unity gain circuit it is unstable