I just replaced some of the OPA2134 in my xover with LM4562.
OPA2134 were themselves replacing tl082.
LM4562 sounds much much better than the BurrBrown chips, however they also run much hotter. I won't burn my fingers on them but they are noticeably hotter. I still have 2134 on the low pass outputs so I can very easily feel the difference in temperature.
I have the impression that the voltage regs run also more hot than before but I may be wrong.
All in all it sounds great at the moment but I'm a bit worried something might be wrong.
I really don't wanna go back to OPA2134, as they sound hazy with a splashy treble in comparison to LM4562...
OPA2134 were themselves replacing tl082.
LM4562 sounds much much better than the BurrBrown chips, however they also run much hotter. I won't burn my fingers on them but they are noticeably hotter. I still have 2134 on the low pass outputs so I can very easily feel the difference in temperature.
I have the impression that the voltage regs run also more hot than before but I may be wrong.
All in all it sounds great at the moment but I'm a bit worried something might be wrong.
I really don't wanna go back to OPA2134, as they sound hazy with a splashy treble in comparison to LM4562...
Depending on operating voltage LM4562 might get quite warm, so nothing might be wrong. At the same time, this chip likes to create spontaneous oscillators from anything, so you might be having some problems in this area. A fast scope will tell.
The fact that you hear such a pronounced difference between the OPA 134 and the LM 4562 points in the direction of something untoward happening. Normally, you would expect them to sound exactly identical, when both are implemented correctly.
Btw, there is nothing wrong with the OPA134 sound wise. For best overall (measured) performance in actual circuitry, the NE5532 might still beat the other 2 chips you mentioned. Worth trying.
The fact that you hear such a pronounced difference between the OPA 134 and the LM 4562 points in the direction of something untoward happening. Normally, you would expect them to sound exactly identical, when both are implemented correctly.
Btw, there is nothing wrong with the OPA134 sound wise. For best overall (measured) performance in actual circuitry, the NE5532 might still beat the other 2 chips you mentioned. Worth trying.
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If the '4562 sounds that much better than the '2134, then there's obviously something not quite right here.
The '2134 is a FET input device and the '4562 a bipolar input device.
Never heard the '2134's treble described as "splashy", but then again I'm no fan of the '4562's "sterile" and "lifeless" sound.
If DC offset isn't an issue, I would try the NE5532 suggested above or the LM833N.
Either should sound better than a '4562.
The '2134 is a FET input device and the '4562 a bipolar input device.
Never heard the '2134's treble described as "splashy", but then again I'm no fan of the '4562's "sterile" and "lifeless" sound.
If DC offset isn't an issue, I would try the NE5532 suggested above or the LM833N.
Either should sound better than a '4562.
Well, personal taste cannot be discussed I guess!
As for me, my crossover sounds with LM4562 the closest my system used to sound BEFORE bi-amping. It sounds completely transparent, with the added benefits (DYNAMICS!) bi-amping brings to the table.
OPA2134 has a much more pronounced sonic signature IMO.
It is not unpleasant at all, but it is there. Slightly laid back midrange and a tizzy splashy treble. It is all relative of course. I do not find LM4562 sterile at all. I do not find OPA2134 unlistenable, fat from it. But I always felt I could "hear the crossover" and now I hear more of my system, the crossover isn't the "weak link" anymore.
NE5532... I know some people only swear by it (mostly "objectivists) but I find it to lack refinement. Not a bad chip, especially for the price, but we've done better since.
Probably part of our preferences are due to the fact all those IC feel more or less at home in a given circuit, but it doesn't tell all.
As for me, my crossover sounds with LM4562 the closest my system used to sound BEFORE bi-amping. It sounds completely transparent, with the added benefits (DYNAMICS!) bi-amping brings to the table.
OPA2134 has a much more pronounced sonic signature IMO.
It is not unpleasant at all, but it is there. Slightly laid back midrange and a tizzy splashy treble. It is all relative of course. I do not find LM4562 sterile at all. I do not find OPA2134 unlistenable, fat from it. But I always felt I could "hear the crossover" and now I hear more of my system, the crossover isn't the "weak link" anymore.
NE5532... I know some people only swear by it (mostly "objectivists) but I find it to lack refinement. Not a bad chip, especially for the price, but we've done better since.
Probably part of our preferences are due to the fact all those IC feel more or less at home in a given circuit, but it doesn't tell all.
As an objectivist, I would caution against the use of the 4562, unless great attention is given to lay-out and shielding.
This thread may show you why (LME49720 is the same chip) Low-distortion Audio-range Oscillator
This thread may show you why (LME49720 is the same chip) Low-distortion Audio-range Oscillator
My old AB headphone amp was running tl082 that was changed to OPA2134 also.
But I tested it with 4562 and it was heating up quite fast. Most probably oscillating, but never checked if it is really oscillating.
Recently built a class A amp with 4562 and opa is totally cool. But now it has more filtering at input and also 200p connected from out to input. So it is tamed.
But last time when the phone was close the the amp, it picked up the mobile signal instantly
So the circuit itself is important not to drive it to oscillation.
But I tested it with 4562 and it was heating up quite fast. Most probably oscillating, but never checked if it is really oscillating.
Recently built a class A amp with 4562 and opa is totally cool. But now it has more filtering at input and also 200p connected from out to input. So it is tamed.
But last time when the phone was close the the amp, it picked up the mobile signal instantly
So the circuit itself is important not to drive it to oscillation.
You don't haul caravans with a Ferrari, the 4562 is a Ferrari and audio is a caravan.
That's why you need a Porsche http://www.dpccars.com/gallery/var/resizes/Supercars-Towing-Trailer/Supercar Towing Trailer - 09.jpg
That's why you need a Porsche http://www.dpccars.com/gallery/var/resizes/Supercars-Towing-Trailer/Supercar Towing Trailer - 09.jpg
I've never had a problem with a 4562 or any opamp with RF for that matter. And no mobile phone noise whatsoever.
1. 1nF cap from the RCA shield connector directly to the aluminium chassis right at the input. This shunts RF picked up by the shield to the equipment chassis (conductive)
2. On the inputs from the outside world, I always use either a 1k + 220pF L pad or a 220 Ohm + 1nF. This provides very useful RF attenuation
FET input opamps do have better RFI resilience because of the lower gm.
Re your LM4562 running warm and the 'splashy' treble - might be oscillation. The TL07X series can drive 100pF and probably a bit more comfortably - ULGF ~3MHz and the OLG is around 400k IIRC - this is low. The phase shift plots in the data sheet look very clean. So, it might be that the replacement devices are running into a bit of a problem. Have you tried putting the TL7X devices back in and seeing what it sounds like? A circuit would certainly help to get to the root cause of your problem.
I have used the LM4562 in a simple line preamp, and I am using for some specialist functions in in some commercial gear - they do not run very warm - no different to 5432 from my experience.
1. 1nF cap from the RCA shield connector directly to the aluminium chassis right at the input. This shunts RF picked up by the shield to the equipment chassis (conductive)
2. On the inputs from the outside world, I always use either a 1k + 220pF L pad or a 220 Ohm + 1nF. This provides very useful RF attenuation
FET input opamps do have better RFI resilience because of the lower gm.
Re your LM4562 running warm and the 'splashy' treble - might be oscillation. The TL07X series can drive 100pF and probably a bit more comfortably - ULGF ~3MHz and the OLG is around 400k IIRC - this is low. The phase shift plots in the data sheet look very clean. So, it might be that the replacement devices are running into a bit of a problem. Have you tried putting the TL7X devices back in and seeing what it sounds like? A circuit would certainly help to get to the root cause of your problem.
I have used the LM4562 in a simple line preamp, and I am using for some specialist functions in in some commercial gear - they do not run very warm - no different to 5432 from my experience.
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My experience with the '4562 and '49720 are just the opposite.
Even in low 6dB gain line stages I've built using very good shunt regulators to power them, I've heard hum and other garbage that I have not heard in many AD or LT op-amps. Just passing my over these worthless National/TI offerings would create noise!
With the '4562/49720's p_ss poor PSRR, its willingness to amplify any RF garbage around it(including a human hand!) combined with its sterile and lifeless SQ, I wished TI would discontinue this chip ASAP.
Even some of the JRC dual offerings can mop the floor with the '4562 when it comes to RF rejection and yes...even SQ.
I threw all my '4562/'49720s in the trash where they belong!
The OP never stated that the '4562 had "splashy" treble. He was referring to the the OPA2134.
Unfortunately, the fact is that the 4562 and the whole NS family is extremely sensitive to air coupled interference. I would be able to write a whole thread supported with measurements on this issue, but I am skeptical it makes any sense. Some of my posts on this can be searched in the diyaudio forum. My experience has lasted for more than 10 years, with parts from many production series. The issue may be measured with sensitive spectrum analysis as mains supply multiples in the spectrum.
This issue is similar to many audiophile topics. The part is loved and hated and so are the posts. However, there is a solution, purely technical, of course.
hints:
- use double sided PCB with with shielding groundplane
- bypass capacitors to be placed close to IC power supply pins, with second end soldered to the groundplane
- use input RC filter
- the whole PCB placed in a well shielded metal box (Al, Cu)
If these construction rules are fulfilled, the part will have clean output. But, in any case, it is much more sensitive to EMI then e.g. OPA2134, but also much more compared to NE5532. I have plenty of comparative measurements.
This issue is similar to many audiophile topics. The part is loved and hated and so are the posts. However, there is a solution, purely technical, of course.
hints:
- use double sided PCB with with shielding groundplane
- bypass capacitors to be placed close to IC power supply pins, with second end soldered to the groundplane
- use input RC filter
- the whole PCB placed in a well shielded metal box (Al, Cu)
If these construction rules are fulfilled, the part will have clean output. But, in any case, it is much more sensitive to EMI then e.g. OPA2134, but also much more compared to NE5532. I have plenty of comparative measurements.
Duh... I was under the impression LM4562 was created specially for audio! I wonder if anybody ever used it in a different application. I doubt it!
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