Hi lndm,
You might be further ahead to replace them with a buffer. They serve two purposes. One is to isolate the previous circuits from loading due to capacitance or just plain resistance. The second is to provide a low impedance output to better drive the previously mentioned loads. S/N may be improved with a low impedance output as well by shunting picked up noise.
-Chris
You might be further ahead to replace them with a buffer. They serve two purposes. One is to isolate the previous circuits from loading due to capacitance or just plain resistance. The second is to provide a low impedance output to better drive the previously mentioned loads. S/N may be improved with a low impedance output as well by shunting picked up noise.
-Chris
Well anatech, there was a chip I didn't identify that had audio. It fed into a 3k resistor to ground and into an op amp connected as a unity gain buffer. This fed both a headphone stage and another unity gain buffer. This then fed a discrete transistor stage -> RCA's.
I think at the time, perplexed, I thought it was a little ridiculous. Then I decided I would just assume these stages were there to mask some grain or something.
Anyhow, I much preferred the after result.
I think at the time, perplexed, I thought it was a little ridiculous. Then I decided I would just assume these stages were there to mask some grain or something.
Anyhow, I much preferred the after result.
Yes. If I remember (don't have it now), it did become a little clicky between tracks or something. This is something I consider less important than the sound quality. And yes, I do play it by ear sometimes. It doesn't always make the most sense, but I understand there are always going to be obscured factors that I may or may not see.
Usually (not always) I find simplicity works. It often gives me a clue when I can't think of anything better, and it often works for me.
Usually (not always) I find simplicity works. It often gives me a clue when I can't think of anything better, and it often works for me.
I agree with anatech. I have also serviced SSL 9000 series consoles here in the metro New Orleans area (Balance Recording Studio and Trent Reznor's NIN Nothing Studio). SSL used many single opamp NE5534s in the signal chain. One 'trick' that they incorporate is placing a 10k resistor between the -15 volt supply and the 5534's output terminal. I believe this forces the opamp's output stage into Class A operation. I wouldn't try this with a dual opamp due to the heat dissipation native to Class A operation. Another interesting 'trick' is that the inerstage coupling method was two back-to-back polarized electrolytics, with their (+) leads joined together. At this common anode junction, a DC biasing scheme formed by a two resistor voltage divider developed about +2 volts on anode of the electrolytic caps. This helped to keep the electrolyte chemically "alive" (thereby lasting longer) and helped minimize distortion associated with large-value electrolytic coupling capacitors.
Pulling down the output of some op amps may improve them, but don't mess with good ones that way.
Besides, there are a ton of op amps in a console. It would take a long time to do all of them. There was an article on this but I can't remember who the author was. Take it with a grain of salt.
Pro audio easily succumbs to it's own fads.
-Chris
Besides, there are a ton of op amps in a console. It would take a long time to do all of them. There was an article on this but I can't remember who the author was. Take it with a grain of salt.
Pro audio easily succumbs to it's own fads.
-Chris
Haven't read all of this but seems interesting
http://www.zero-distortion.com/tests/opamps/opamps.htm
It gets more down to it at the page called some likely candidates
http://www.zero-distortion.com/tests/opamps/opamps.htm
It gets more down to it at the page called some likely candidates
OP amp
Hi friend i agreed 5532 is better than 4558, but i am asking about LT1057, already i have tried LF353,TLO72,82,TLC272,4558,4556,TDA2320,LM358 but i am not impressed i need more detailed sound, every ic's are has a different quality but which is has most special quality, 5532 is low noise ic this one is better for sub woofer circuit, but treble is not good, TLO82 is detailed and clear sound treble also good but bass is not deep, thats only i am asking which ic better.
By
Kamal
Hi friend i agreed 5532 is better than 4558, but i am asking about LT1057, already i have tried LF353,TLO72,82,TLC272,4558,4556,TDA2320,LM358 but i am not impressed i need more detailed sound, every ic's are has a different quality but which is has most special quality, 5532 is low noise ic this one is better for sub woofer circuit, but treble is not good, TLO82 is detailed and clear sound treble also good but bass is not deep, thats only i am asking which ic better.
By
Kamal
It should be OK but it's nothing particularly impressive. Not the quietest or fastest by a long shot but it is old if the copyright date (1989) is correct. If you already have them go for it, If not, look elsewhere. It's outstandingly blah.
As far as 5532s go, LOTS of commercial audio gear uses them.
G²
Kamal,
for audio, the parameter that limits the sound quality of an opamp circuit is mostly the Slew Rate. For those ICs you have used, check their SR and you will find that the quality of the sound corelate highly with the SR.
Some Opamps are high precision types and usually used for high precision devices. These opamps (OP) usually have high quality build and even though have low slew rate they tend to sound good.
Some opamps are low noise types (usually has FET input). It is good of course to have a low noise opamp (e.g. for mic preamp), but SR is still more important for most situation.
High SR opamps are expensive. Most popular brands are AD and THS. The cheap opamp that has high slew rate (and sounds good!) is OPA2134.
Look at below the SR of several opamps, you can see that these opamps have their reputation in accordance with their SR:
LM471 = 0.5 V/us
4558 = 1.2
4560 = 4 (when JRC is used, 4560 is usually used in more expensive amp)
5332 = 9
2134 = 20
AD827 = 300
ADD: For a buffer circuit (Gain=1) make sure you don't put in opamps that has "zero gain instability". Better not to roll out opamps in such circuit.
for audio, the parameter that limits the sound quality of an opamp circuit is mostly the Slew Rate. For those ICs you have used, check their SR and you will find that the quality of the sound corelate highly with the SR.
Some Opamps are high precision types and usually used for high precision devices. These opamps (OP) usually have high quality build and even though have low slew rate they tend to sound good.
Some opamps are low noise types (usually has FET input). It is good of course to have a low noise opamp (e.g. for mic preamp), but SR is still more important for most situation.
High SR opamps are expensive. Most popular brands are AD and THS. The cheap opamp that has high slew rate (and sounds good!) is OPA2134.
Look at below the SR of several opamps, you can see that these opamps have their reputation in accordance with their SR:
LM471 = 0.5 V/us
4558 = 1.2
4560 = 4 (when JRC is used, 4560 is usually used in more expensive amp)
5332 = 9
2134 = 20
AD827 = 300
ADD: For a buffer circuit (Gain=1) make sure you don't put in opamps that has "zero gain instability". Better not to roll out opamps in such circuit.
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i want use this ic's for tone control circuit. Now i have used LF353 for input it is act as a current driver and 2 nd stage is Low and Lo mid this stage also used 353,3rd one is TLO72 this one is high mid and high frequency control controls are shelving type circuit and using 10k volume op stage is NE571 DC volume control power amp is TDA7294. Bass and treble is ok but i miss some details and mid also not very effective. thats only i need to try some special ic also i have try 4560, but 353 and tlo72 pair is little better than other ic but still i am not satisfied. I am also need best DC volume control circuit using NE571. My circuit is little noisy,.
By
Kamal
By
Kamal
Hi Kamal,
The IC type is not involved with your problem at all. The NE5532A and NE5534A are both excellent choices, depending on your circuit. The old standbys that you don't like are still current for one reason. They are both holding their own with today's devices.
You may not like this answer, but this is a fact. In addition, the 5532 has far better output drive, very low distortion at these lower impedance loads and a superior common mode rejection ratio. ie they perform well as voltage followers. Sonically speaking, the 5532 outperforms the '071,'072 and '074 families easily. The one major difference is that the '72 family is J-Fet input whereas the 5532 is a bipolar input device.
Your situation is most probably caused by either the type of parts you are using, or the layout of your circuit. My money is on the part types you are using for resistors and capacitors. Concerns over slew rates are unfounded unless you are using a 741 type device. 0.5 V/usec is a marginal speed, I wouldn't use these. Anything over say, 2 V/usec will be fine unless you are looking for very high gain. Suffice to say that the 5532 will not be a problem in this regard.
There are many facets to applying an op amp type to a circuit. In less demanding applications like the one you are using, cost might be the deciding factor. That is unless the marketing department demands a specific part for marketing purposes. Other issues beyond simple slew rate will be CMRR, PSRR, distortion type and distortion level (applied to the specific circuit and gain structure). You can't just take the number off the data sheet and claim that. Knowing this, an LM4562 might be one of the better parts to use unless you can afford 2604 or other very high end parts.
Why not use a standard volume control?? You are using an NE571 as a DC volume control! How old is that part number? (it's old). This part alone can squash any sound quality that has made it that far. Look at the parts National have introduced recently. There are better level controls out there. The premium part for Japanese op amps might be the NJM2068. Look it up. Low noise and useful for RIAA circuits.
-Chris
The IC type is not involved with your problem at all. The NE5532A and NE5534A are both excellent choices, depending on your circuit. The old standbys that you don't like are still current for one reason. They are both holding their own with today's devices.
You may not like this answer, but this is a fact. In addition, the 5532 has far better output drive, very low distortion at these lower impedance loads and a superior common mode rejection ratio. ie they perform well as voltage followers. Sonically speaking, the 5532 outperforms the '071,'072 and '074 families easily. The one major difference is that the '72 family is J-Fet input whereas the 5532 is a bipolar input device.
Your situation is most probably caused by either the type of parts you are using, or the layout of your circuit. My money is on the part types you are using for resistors and capacitors. Concerns over slew rates are unfounded unless you are using a 741 type device. 0.5 V/usec is a marginal speed, I wouldn't use these. Anything over say, 2 V/usec will be fine unless you are looking for very high gain. Suffice to say that the 5532 will not be a problem in this regard.
There are many facets to applying an op amp type to a circuit. In less demanding applications like the one you are using, cost might be the deciding factor. That is unless the marketing department demands a specific part for marketing purposes. Other issues beyond simple slew rate will be CMRR, PSRR, distortion type and distortion level (applied to the specific circuit and gain structure). You can't just take the number off the data sheet and claim that. Knowing this, an LM4562 might be one of the better parts to use unless you can afford 2604 or other very high end parts.
Why not use a standard volume control?? You are using an NE571 as a DC volume control! How old is that part number? (it's old). This part alone can squash any sound quality that has made it that far. Look at the parts National have introduced recently. There are better level controls out there. The premium part for Japanese op amps might be the NJM2068. Look it up. Low noise and useful for RIAA circuits.
-Chris
I think Chris is right that the opamp is not your main problem here.
Your description of the sound is mostly the sound of TDA7294 mosfet amp. Yes, you can solve the problem a bit with a suitable/matching preamp.
A slew rate issue is not really important when the opamp is not the bottleneck in your system. Even the 0.5V/us 471 may be suitable for your system. Compared to other low SR opamps, 471 have a unique character in that they don't kill the dynamics of the sound (that's why I still stock many of them, and they are still widely used, not because they are cheap!). But they are very noisy, hence workaround with the power supply is a must, and because the noise is already a problem with your system, I won't suggest the 471 here.
As for IC based volume control, I have no experience as I naturally have had suspicion about them, so I always replaced them without even trying to hear or compare the real performance.
Theoretically you need a better drive for the mosfet amp. That's why Chris suggested a BJT-input 5532. As he said, you may not like to hear it but the 5532 has far better output drive, very low distortion at these lower impedance loads.
I pity you that you like 353 (13V/us, JFET) and 072 (16V/us, JFET) more than 5532 (9V/us, BJT) the opamp choice of experts
But if you want to benefit from 5532 drive capability, you should be careful in placing another load in parallel with the actual load. By "removing" the 571 you might hear benefit. Or, how about putting the volume control before the opamp? Chris will tell you if it is possible (I don't know about this IC).
But if you have schematic, it is better if you post it. Often, sound characteristics can be altered by means of changing secondary components, not by changing opamp.
If you insist on better opamp, and if you have the money, buy the high slew rate opamp such as the AD one. You can kill me if you don't hear huge improvement
And if AD stuff is not good enough for you, then it is time for you to get rid of opamps from your audio chain 
EDIT: Oh, and don't forget the effect of power supply. 78XX regulator will kill the dynamic of the sound. I don't know about your ears, but I believe you can hear improvement if you use LM317 regulator instead of 78XX one. If you used 78XX and you replaced it with a simple LM317, you would hear a little more noise, but the benefit is more.
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