LM 4562

bhobba · « **on:** 21 Mar 2009, 04:40 am »

Hi Hugh and All

Just tinkering around again and finding out a bit more about one of my favorite products, the LM 4562 op amp; an op amp that was actually, horror of horrors, designed not just using theory, but by listening (heaven forbid). Found out some really high end stuff is using them biased into class A and with an emitter follower output stage capacitor coupled. Seems they recon the better capacitors these days are so good it is close to copper (I presume they mean stuff like the platinum sonicaps) and that in class A the LM 4562 is so good its not worth going discreet.

Anyone any thoughts, observations, comments, ideas or whatever? Maybe something to consider for a future Aspen product?

Thanks
Bill

andyr · « **Reply #1 on:** 21 Mar 2009, 07:08 am »

Quote from: bhobba on 21 Mar 2009, 04:40 am

Hi Hugh and All

Just tinkering around again and finding out a bit more about one of my favorite products, the LM 4562 op amp; an op amp that was actually, horror of horrors, designed not just using theory, but by listening (heaven forbid). Found out some really high end stuff is using them biased into class A and with an emitter follower output stage capacitor coupled. Seems they recon the better capacitors these days are so good it is close to copper (I presume they mean stuff like the platinum sonicaps) and that in class A the LM 4562 is so good its not worth going discreet.

Anyone any thoughts, observations, comments, ideas or whatever? Maybe something to consider for a future Aspen product?

Thanks
Bill

Hi Bill,

Have you seen any comparisons of the LM 4562 vs. other "popular" opamps? From memory, a middle-European guy with the moniker "DVV" used to post here and his site contains some comparative reviews ... although they must be 5-10 years old, now. He liked the AD826 as it had a good bass response. (But I've lost his website!

)

Regards,

Andy

AKSA · « **Reply #2 on:** 21 Mar 2009, 07:36 am »

Bill,

I seem to recall this opamp being picked up by Silicon Chip for a preamp. It's claim to fame was extremely low measured distortion; I'm always suspicious of this, because in my experience very low distortion usually means mostly higher order, which sounds clean but sterile.

That is not to condemn it, but until I've built one and listened extensively, I wouldn't like to say either way.

Cheers,

Hugh

gaetan8888 · « **Reply #3 on:** 22 Mar 2009, 06:34 am »

Quote from: AKSA on 21 Mar 2009, 07:36 am

That is not to condemn it, but until I've built one and listened extensively, I wouldn't like to say either way.

Cheers,

Hugh

Hello Hugh

That would be a very good ideas, you can have, without problems, LM4562 samples from National Semiconductor.

Have you try and listen any others opamps, like the AD825, OPA637, OPA627, OPA2134, etc... ?

Bye

Gaetan

gaetan8888 · « **Reply #4 on:** 22 Mar 2009, 06:42 am »

Hello guy's

Maby we are better with the oldies, like the AD825, OPA637, OPA627 ?

Those high speed low distortions opamp like LM4562 need a very high nfb and a very good decoupling.

They don't show, in the data sheet, the distortion spectrum, but I would not be surprise of higher order distortions in the LM 4562, and some say that the LM4562 do have a quite flat soundstage.

Here is the distortions vs output of the LM4562, even taking account of the noise floor it goes quite high at low level output;

Bye

Gaetan

andyr · « **Reply #5 on:** 22 Mar 2009, 07:07 am »

Quote from: gaetan8888 on 22 Mar 2009, 06:42 am

Maybe we are better with the oldies, like the AD825, OPA637, OPA627 ?

Gaetan

Can you explain what the difference is between the AD825 & the AD826?

Thanks,

Andy

bluesky · « **Reply #6 on:** 22 Mar 2009, 08:51 am »

One thing that never ceases to amaze me about Silicon Chip is that they never comment on how the end product sounds. I actually think Silicon Chip does a lot of good for audio electronics and their magazine has given me a lot of reading pleasure and has also taught me a lot.

However even some of their so called "objective measurements" just don't seem to add up when I look at the various graphs published. I borrowed some magazines from my local library and have been reading their analysis on this amp. The claim of having "typically 0.0006% THD" just does not appear on the graphs and is far closer to 0.001%, this is still very good but it is not what they are claiming.

Music is far more than just measurments as Hugh and others have stated, there is much more to audio reproduction that just THD. If it was that simple why is it that a Stradavarius sounds so good? The first, and only time, I heard a Stradavarius was a defining moment for me. A friend had shouted me to a trip to a concert and the guest violinist was just amazing and the clarity and tone was a stand out. I only discovered that it was a Stradavaruius being played afterwards when I read the program notes and this insight made a big impression on me to show that there is more to music that just frequency measurements in a lab.

Bluesky

MikeC · « **Reply #7 on:** 22 Mar 2009, 06:49 pm »

Hi

The LM4562 is currently the opamp for use in the Orion crossover, but I haven't tried it yet. Some others like West have, I think. There is also some comment on the newest range of National op-amps on DIY Audio.

Regards

Mike

whubbard · « **Reply #8 on:** 23 Mar 2009, 02:06 am »

Mike,
I'm mainly using the OPA2107, mixing in the LM4562. It's going to take some time, frankly a lot of time, but I hope to find a nice mix.

-West

ginger · « **Reply #9 on:** 23 Mar 2009, 03:04 am »

I've built 2 of the Silicon Chip "Professional" Preamps using the OPA2134 Opamps.Sound was very cold, which is characteristic of most opamps but was'nt helped by the fact that application notes which specifically state that they (the OPA2134) perform better in inverting mode than non-inverting mode were ignored. In addition there were far too many coupling caps (non-polarised electrolytics) in the circuit. I ditched most of them and used Blackgate N were they were required. Also used Blackgates for the power supplies.
These preamps went to 2 of my nieces together with valve power amplifiers. The combination of OPA2134 based preamp and 6V6 tube based power amp sounded pretty darn good.
Just a variation on Hugh's theme of tube based preamp and SS based power amp.
Cheers,
Ian

VYnuhl.Addict · « **Reply #10 on:** 23 Mar 2009, 03:53 am »

Quote from: andyr on 21 Mar 2009, 07:08 am

Quote from: bhobba on 21 Mar 2009, 04:40 am

Hi Bill,

Have you seen any comparisons of the LM 4562 vs. other "popular" opamps? From memory, a middle-European guy with the moniker "DVV" used to post here and his site contains some comparative reviews ... although they must be 5-10 years old, now. He liked the AD826 as it had a good bass response. (But I've lost his website! )

Regards,

Andy

Hi Andy,

Dejan's site yes, he swears by the AD826 for everything and as a drop in for Marantz Cd players too, I always found his site somewhat misinformative especially when it came to overbiasing Class A/B amps but he did spend alot of time listening. Tangentsoft also has a comparison of OpAmps for headphone amp use. atleast most of the well known ones. After years of fiddling with opamps Ive learned there is no one since fits all, they all sound different, some subjectively better or worse, but this always changes based on application hence why discreet will never lose popularity among the pickiest. Ic's are damn easy to work with though, make designing a cinch but Ive always found every Ic benefits from a discreet buffer follower, always, even in a preamp to these ears..I tend to agree with Hugh these days in that the THD distribution is more important with a descent from the 2nd harmonic onward rather than a general THD figure which is very vague in all opamp datasheets.

Colin

Greg Erskine · « **Reply #11 on:** 23 Mar 2009, 05:42 am »

I think it was the Silicon Chip headphone amp that Hugh was thinking of, it has the LM4562 specified.

The guys over at Rock Grotto Audio reckon the metal can version LM4562HA is the go.

kyrill · « **Reply #12 on:** 23 Mar 2009, 06:19 pm »

THe DEQX I own is revamped in AU by the manufacturer by replacing multiple opamps for the LM 4562

The sound is not sterile but very very transparent and dare i say musical for a digital device.

carusoracer · « **Reply #13 on:** 24 Mar 2009, 12:16 am »

I'm no expert in the OpAmps but I really lke the LM4562 in my Shanling T 200A
It is very musical and the soundstage is very wide.

jules · « **Reply #14 on:** 24 Mar 2009, 12:42 am »

Adding to the mix:

I'm using them in my CDP and while I agree about the transparency and soundstage, there's a certain amount of edginess in the top-end that I don't like all that much. They've been in there for nearly a year now and I'm quite used to them but based on my initial impression, I'll be replacing them audio-gd discrete component op-amps [similar to Burson devices]. Going back to what Hugh, gaetan and others have said, distortion seems a likely culprit.

Jules

gaetan8888 · « **Reply #15 on:** 24 Mar 2009, 05:21 am »

Quote from: andyr on 22 Mar 2009, 07:07 am

Quote from: gaetan8888 on 22 Mar 2009, 06:42 am

Maybe we are better with the oldies, like the AD825, OPA637, OPA627 ?

Gaetan

Can you explain what the difference is between the AD825 & the AD826?

Thanks,

Andy

Hello Andy

The AD825 are for audio and have a 41mhz bandwith, 125 v/us slew rate, with 12 nv/hz noise at 10khz.

The AD826 are for video and have a 50mhz bandwith, 350 v/us slew rate, with 15 nv/hz noise at 10khz.

Some was prefered the sound of the AD826.

Bye

Gaetan

gaetan8888 · « **Reply #16 on:** 24 Mar 2009, 05:30 am »

Hello carusoracer and Jules

Is the LM4562 do better than the AD825 for transparency, soundstage and sweet musicality ?

For me a 3D deep and wide soundstage are very important.

Thank

Bye

Gaetan

jules · « **Reply #17 on:** 24 Mar 2009, 05:41 am »

Hi gaetan,

sorry, I can't give an opinion on the AD825 v LM4562. For what it's worth, the LM4562 is v good on 3D, soundstage and transparency but as I said above .......

Jules

gaetan8888 · « **Reply #18 on:** 24 Mar 2009, 05:51 am »

Quote from: jules on 24 Mar 2009, 05:41 am

Hi gaetan,

sorry, I can't give an opinion on the AD825 v LM4562. For what it's worth, the LM4562 is v good on 3D, soundstage and transparency but as I said above .......

Jules

Hello Jules

You mean the edginess in the top-end...

Hum... I'm very sensitive to mid and high frequency distortion or harshness.

Thank

Bye

Gaetan

andyr · « **Reply #19 on:** 24 Mar 2009, 06:55 am »

Quote from: jules on 24 Mar 2009, 12:42 am

I'm using them in my CDP and while I agree about the transparency and soundstage, there's a certain amount of edginess in the top-end that I don't like all that much. They've been in there for nearly a year now and I'm quite used to them but based on my initial impression, I'll be replacing them audio-gd discrete component op-amps [similar to Burson devices]. Going back to what Hugh, gaetan and others have said, distortion seems a likely culprit.

Jules

Hi jules,

Why did you pick the audio-gd discrete-component opamp over the Burson "opamp"? I have heard people comment on a harsh top-end with the Burson buffer and I wondered whether the Burson opamp replacement would sound as harsh?

I'm interested in trying out a "discrete opamp" replacement for the opamp used in the GK-1 phono stage.

Regards,

Andy