Lm4562
Strangely, this week I have heard two reports from disparate sources of LM4562s that have odd LF noises - the description sounds like classic popcorn noise and was described as "a low level 'rustling' in the background". It went away when new units were swapped into the circuit to replace the offenders.
Mark, do you know of any issues with this? What is the variation in noise (voltage and current) from device-to-device and lot-to-lot? How far do devices deviate from typical, and are the max noise specs really tested? I gather from footnote 7 on the spec table that I can't heavily count on any specs.
p.s., still curious about that magic 'leakage' test to sort out the best units.
Strangely, this week I have heard two reports from disparate sources of LM4562s that have odd LF noises - the description sounds like classic popcorn noise and was described as "a low level 'rustling' in the background". It went away when new units were swapped into the circuit to replace the offenders.
Mark, do you know of any issues with this? What is the variation in noise (voltage and current) from device-to-device and lot-to-lot? How far do devices deviate from typical, and are the max noise specs really tested? I gather from footnote 7 on the spec table that I can't heavily count on any specs.
p.s., still curious about that magic 'leakage' test to sort out the best units.
A few months ago I completed my pre-amp which is based on the
LM4562. I have to say I am very pleased with it, although I would probably do a few things differently 2nd time around on the headphone amp. This was a 'stop-gap' project. Its a single ended to balanced out put design that uses 1 x 4562 per channel, and a 25k volume pot. Gain is 2x. It is is absolutely silent. I'm driving a set of B&W 703's with a
250W amp, and these op-amps sound very good indeed.
I am working on another design now (but this is discrete based).
You can take a look here:- http://www.diyaudio.com/forums/solid-state/96192-post-your-solid-state-pics-here-66.html
Starting at post 654 about 1/3 down the page.
🙂
LM4562. I have to say I am very pleased with it, although I would probably do a few things differently 2nd time around on the headphone amp. This was a 'stop-gap' project. Its a single ended to balanced out put design that uses 1 x 4562 per channel, and a 25k volume pot. Gain is 2x. It is is absolutely silent. I'm driving a set of B&W 703's with a
250W amp, and these op-amps sound very good indeed.
I am working on another design now (but this is discrete based).
You can take a look here:- http://www.diyaudio.com/forums/solid-state/96192-post-your-solid-state-pics-here-66.html
Starting at post 654 about 1/3 down the page.
🙂
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Hallo Mark / Audioman54
Since You are deep expert in operational amplifiers and Hi-end audio electronic design ,I wish submit to You ,and everyone interested ,my project for a reference (hope), balanced output headphone amplifier in “SuSy” configuration for a very low loads (25-60 Ohm).
Since I’m not a skilled designer (this is my first project….) I don’t understand if the dc offset of the output stage is nulled or not by the crossed feedback of the "SuSy" configuration. In any case, I’ve added a hypothesis for two kind of nulling circuit ,one “manual” and another “automatic” but I’m not sure if this is the cure to control both legs of balanced output signal….
My questions are :
In your experience ,this project can work, perform and sound good as expected or need to be refined or redesigned maybe with others chips? ( I like very detailed, analytic, transparent, fast and dynamic sound and I have read that these current feedback Chips have the sound characteristics that I prefer.)
The circuit can work properly without nullig circuit and if the ancillary offset control circuit is requested, what is the best solution?
My friend tell to me is better to put face to face in physical contact the two LT1210 for a optimal thermal tracking. For a similar reason is better to use a LME49720 instead of two LME49710?( but the single opamp solution is better for more freedom in alternative parts choice and future tweaking)
Can You suggest me a right way to do a good PCB ?
(For what I read in the forum, in this fast and large b.w. circuits is important to place the decoupling capacitors near as possible to the chips. Also important is to do a separate star signal ground and star power ground routed to common ground of the power supply.)
Thank You very much in advance and Merry Christmas !
semola
Since You are deep expert in operational amplifiers and Hi-end audio electronic design ,I wish submit to You ,and everyone interested ,my project for a reference (hope), balanced output headphone amplifier in “SuSy” configuration for a very low loads (25-60 Ohm).
Since I’m not a skilled designer (this is my first project….) I don’t understand if the dc offset of the output stage is nulled or not by the crossed feedback of the "SuSy" configuration. In any case, I’ve added a hypothesis for two kind of nulling circuit ,one “manual” and another “automatic” but I’m not sure if this is the cure to control both legs of balanced output signal….
My questions are :
In your experience ,this project can work, perform and sound good as expected or need to be refined or redesigned maybe with others chips? ( I like very detailed, analytic, transparent, fast and dynamic sound and I have read that these current feedback Chips have the sound characteristics that I prefer.)
The circuit can work properly without nullig circuit and if the ancillary offset control circuit is requested, what is the best solution?
My friend tell to me is better to put face to face in physical contact the two LT1210 for a optimal thermal tracking. For a similar reason is better to use a LME49720 instead of two LME49710?( but the single opamp solution is better for more freedom in alternative parts choice and future tweaking)
Can You suggest me a right way to do a good PCB ?
(For what I read in the forum, in this fast and large b.w. circuits is important to place the decoupling capacitors near as possible to the chips. Also important is to do a separate star signal ground and star power ground routed to common ground of the power supply.)
Thank You very much in advance and Merry Christmas !
semola
Attachments
Hi, Semola,
Your description is very close to a single chip. You can check OPA1632. It has SuSy balanced output, and a pin for adjusting DC output.
Your description is very close to a single chip. You can check OPA1632. It has SuSy balanced output, and a pin for adjusting DC output.
Thank You lumanauw for the suggestion,
but I think is not ideal for a direct coupling with a low impedance headphone.
The performances are very good but specified for a 600 Ohm load.
moreover is a smd component and it need a soldered area under the chip for thermal dissipation.
Not very easy for a DIY realization...
My circuit is conceived for a DIL and TO220 chips. More easy to handle.
Regards
semola
but I think is not ideal for a direct coupling with a low impedance headphone.
The performances are very good but specified for a 600 Ohm load.
moreover is a smd component and it need a soldered area under the chip for thermal dissipation.
Not very easy for a DIY realization...
My circuit is conceived for a DIL and TO220 chips. More easy to handle.
Regards
semola
Here's some opamp inflation fun -- the Asus Xonar Essence ST and STX Soundcards use socketed LM4562's so you can opamp roll to your heart's content. also uses the TI TPA6120A2 cfb headphone driver.
Well national and TI must b e happy, but why use such nice devices on a sound card when an el cheapo discrete circuit for 10c would do the job? I'm amazed.
The soundcard business is at the same unsophisticated level that Receivers were at in the early 80's. Its all about one critical number and a second almost critical number- Signal to noise is the driving issue and 120 dB is the magic number. The distortion numbers are also important but really misquoted on the promo material (.00006% THD?????). Getting to those numbers with $.10 of parts is difficult. And opamps can be a selling point. That card also has a "shield" that isn't electrically connected but illuminated so it looks ominous. However even the Stereophile was not too impressed, with some negative comments about dumb limitations in the card.
I think it's about freeking time for manufacturers to use premium opamps and stop using electrolytic caps in the audio path. It's insane to use NE5532 or any of those crappy JRC opamps in otherwise good products. I've just rolled opamps to LM4562 and bypassed the electrolytic output caps in my E-mu 1212M and the difference is night and day.
While I entirely agree about electrolytics in the signal path... (that's really night and day)
I don't exactly agree about "NE5532 or any of those crappy JRC opamps".
For one: my integrated amp uses a JRC 4570 and it sounds great. I haven't felt the need for the hassle of modifying it for all this time... so it must be good as it is.
Also: a high end brand like Accuphase uses JRC opamps in their very excellent (I listened to one myself) CD players & DACs. The latest (bottom of the range) & extremely appreciated DP-400 CD player has differential PCM1796 DACs followed by an output stage entirely made with JRC 4580's. It's been chosen as the magazine's reference in its price range... and it's been said to have better microdetail than the Bryston BDA-1 DAC which has a fully discrete output stage. 🙂
Accuphase Laboratory, Inc.　DP-400
Bryston BDA-1 External DAC review
Isn't that typically you Andrea, to have opinions on things you haven't heard. But really, do you find NE5532 or any of the JRC amps on par with the best opamps? If you were to design a DAC or an amp, would you use NJM2068 or NE5532 if price wasn't an issue?
Maybe there are better opamps than LM4562. I think there are, but at this level it's a matter of taste. LM4562 is neutral, detailed, cheap and easy to find.
Maybe there are better opamps than LM4562. I think there are, but at this level it's a matter of taste. LM4562 is neutral, detailed, cheap and easy to find.
4562 do seem to sound very neutral but sometimes that's not what you need. In some CD players that makes the sound thin and harsh, in others it makes it more open and musical. To be able to use such good op-amps the preceding circuits must be taken care of and the whole machine considered together.
The old JRC2114 can sound a bit more musical in a Marantz CD63 but ultimately it's a rough grainy sound! Just my opinions...
Simon
The old JRC2114 can sound a bit more musical in a Marantz CD63 but ultimately it's a rough grainy sound! Just my opinions...
Simon
Simon, looking at your comments, and then your avatar, I can only assume that what you are smoking is not tabbaco or some legal derivative thereof.
Homodder . . . clearly a comment plucked from thin air.
Homodder . . . clearly a comment plucked from thin air.
Nopes the air around here is quite thick with cigar smoke as I have some visitors listening to my system, the preamp they listening to uses AD4898 opamps, not bad at all compaired to a copland valve pre one of the guys brought along.
Everyone will have a preference, if the national parts are good enough for you go ahead, I ve found better sounding chips in AD and Texas opamps.
For me, the LM4562 is a limited chip: it's aseptic, and it's not completely smooth sounding. I think I wouldn't change my amp's JRC 4570 for a LM4562.
Try the LME49723 🙂
(or, they say, the LME49725)
Yeah, ideally I'd take the OPA1612 over the LM4562 without hesitation. There might be exceptions though, depending on sonic synergies with other active parts.
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There is an illusion that you can swap opamps and know that you are getting optimum performance. its just not true. Further, switching between fet and bipolar opamps can be quite risky. Without a detailed description of the circuit I think sonic claims about any opamp are at best a suggestion. Also CFB vs. VFB opens another can of worms.
Environmental conditions may affect the sound significantly- the 5532 is extremely resistant to emi making it well suited to switching amp applications, and some of the newer high performance opamps get into trouble in those applications.
Environmental conditions may affect the sound significantly- the 5532 is extremely resistant to emi making it well suited to switching amp applications, and some of the newer high performance opamps get into trouble in those applications.
Yes, well, in the above I made a silent assumption that the circuit accepts a relatively fast, modern bipolar opamp. 🙂
IMO sonic synergy with DAC chips etc. is more decisive...
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