Ha ha AMZ
AMZ - I love those quotes on that link you posted a while back.
In my experience, replacing op amps in new designs rarely does much to improve things. Most people use at least a TL072 or 5532 in commercial products and unless you are doing mic preamping, or really high impedance, low level stuff, the difference will be inaudable, especially when proper ABX testing is done.
That being said, I do tend to use OPA2134's instead of TL072s in our products if audio goes thru them.
When preamping a guitar, depending on the guitar, a TL072 may actually end up being quieter than a 5532 because of the current noise difference. High impedance guitars like strats and tele's and even Humbucker type guitars, have enough noise that you probably still wont notice a difference between any decent op amp. My point about the TL072 being quieter is due to the current noise being lower in it, and if you have a guitar with +100K output impedance, the current noise of a 5532 will make it noisier than a FET input OPAMP, even if the voltage noise is 6db or more worse. When I have plugged in a guitar to an identical preamp with normal volume settings, the buzz from the guitar was soooooooooooooo much louder than the opamp noise that I was cracking up.
The comment about the 4558's sounding more tubey was interesting. I think those old opamps work really well and the slew rate may be why they sound more tubey. They are very slow. If I remember, they clip squarely without inversion which is important. Guitar plucks can be 20dB above the rest of the tone, and very brief, so if you clip them quickly, you wont even hear it. Bell labs said any clipping below about 1mS (900uS) was inaudible and I believe them. In a heavy electric guitar, one must remember that freqs above 10K are often USELESS
<ducking from the audiophile guitarists!> I have seen major mixdown engineers roll off all freqs above 8K on heavy guitars to tighten them up, make them less hissy, and leave that area for other instruments.
Holy Quacamole! I've run on and on. and now I must RUN ON!
CIAO!
PS. I just remembered, dont go tooo crazy over your coupling caps either. Ive actually only seen a few times where the cheapest cap performed audibly or measurably bad. Tube circuits require high voltage caps and that can be a different story. But I have people ask me all the time what caps to use and I say, What do you have laying around? When I can, I just eliminate caps completely in the audio path. THIS IS ONE PLACE A GREAT LOW OFFSET OPAMP CAN HELP OUT!
AMZ - I love those quotes on that link you posted a while back.
In my experience, replacing op amps in new designs rarely does much to improve things. Most people use at least a TL072 or 5532 in commercial products and unless you are doing mic preamping, or really high impedance, low level stuff, the difference will be inaudable, especially when proper ABX testing is done.
That being said, I do tend to use OPA2134's instead of TL072s in our products if audio goes thru them.
When preamping a guitar, depending on the guitar, a TL072 may actually end up being quieter than a 5532 because of the current noise difference. High impedance guitars like strats and tele's and even Humbucker type guitars, have enough noise that you probably still wont notice a difference between any decent op amp. My point about the TL072 being quieter is due to the current noise being lower in it, and if you have a guitar with +100K output impedance, the current noise of a 5532 will make it noisier than a FET input OPAMP, even if the voltage noise is 6db or more worse. When I have plugged in a guitar to an identical preamp with normal volume settings, the buzz from the guitar was soooooooooooooo much louder than the opamp noise that I was cracking up.
The comment about the 4558's sounding more tubey was interesting. I think those old opamps work really well and the slew rate may be why they sound more tubey. They are very slow. If I remember, they clip squarely without inversion which is important. Guitar plucks can be 20dB above the rest of the tone, and very brief, so if you clip them quickly, you wont even hear it. Bell labs said any clipping below about 1mS (900uS) was inaudible and I believe them. In a heavy electric guitar, one must remember that freqs above 10K are often USELESS
<ducking from the audiophile guitarists!> I have seen major mixdown engineers roll off all freqs above 8K on heavy guitars to tighten them up, make them less hissy, and leave that area for other instruments.Holy Quacamole! I've run on and on. and now I must RUN ON!
CIAO!
PS. I just remembered, dont go tooo crazy over your coupling caps either. Ive actually only seen a few times where the cheapest cap performed audibly or measurably bad. Tube circuits require high voltage caps and that can be a different story. But I have people ask me all the time what caps to use and I say, What do you have laying around?
When I can, I just eliminate caps completely in the audio path. THIS IS ONE PLACE A GREAT LOW OFFSET OPAMP CAN HELP OUT!Anyone knows an opamp that isn't much influenced by DC power line noise?
I've got a synth using TL064 opamps and there's a -58dB noise level. Headphones output use a LM386 and it's REALLY noisy. The noise seem to come from power line because when the synth is initializing, there is no noise even if the opamps are powered. Maybe there are mute transistors?
Someone used OPA4124s instead and told there was less noise, but I think he told there was still some.
Also, there are M5222L VCAs that seem pretty rare in it. No datasheets are available, but I found pinouts in a schematic I found somewhere. Thanks to google PDF search, the synth scheme pinout aren't descriptive. These VCAs seem noisy since someone that had these in a video cam bypassed them and used a separate volume control instead . . .
Can replacing the 7806 regulators by something else help? Rectifiers?
I've got a synth using TL064 opamps and there's a -58dB noise level. Headphones output use a LM386 and it's REALLY noisy. The noise seem to come from power line because when the synth is initializing, there is no noise even if the opamps are powered. Maybe there are mute transistors?
Someone used OPA4124s instead and told there was less noise, but I think he told there was still some.
Also, there are M5222L VCAs that seem pretty rare in it. No datasheets are available, but I found pinouts in a schematic I found somewhere. Thanks to google PDF search, the synth scheme pinout aren't descriptive. These VCAs seem noisy since someone that had these in a video cam bypassed them and used a separate volume control instead . . .
Can replacing the 7806 regulators by something else help? Rectifiers?
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