Hi Pavel,
I completely agree with you under those circumstances. However, the input range and output range for test and measurement, and probably telecom too, is less than that level. +- 5 VDC rail are more than fine for that use.
There is nothing holding you back from using these high speed op amps as I/V conversion, then stepping up the level later.
-Chris
I completely agree with you under those circumstances. However, the input range and output range for test and measurement, and probably telecom too, is less than that level. +- 5 VDC rail are more than fine for that use.
There is nothing holding you back from using these high speed op amps as I/V conversion, then stepping up the level later.
-Chris
Hi John,
I was only responding to this statement earlier....
So, what is the common drive level presented to an amplifier input? This is going to be around -20 dB below clipping, right? Being realistic and all that. Keep in mind that these devices are normally rail to rail minus about 200 mV. Not the 2 V less than rail you normally expect from a normal audio op amp.
I was not saying we should move to this type of common rail voltage for general audio work at all. What I was saying was that it was possible to successfully use these devices in audio. BTW, some of these also have very low noise compared to what most products use. These are worth $10 + a piece in production quantities. Like the LMH6624 . I'm not sure if it's what you are looking for, but it's very fast (over a Gigahertz) and very quiet. The link should lead you to a product page. Lot's of different op amps like this listed there.
Again, I am not suggesting that we should use these in audio. I'm only pointing out what reality is. If you poke around, you will see that data conversion products often run at 3.3 VDC, never mind +- 5 VDC. Heat, you know.
-Chris 😉
I was only responding to this statement earlier....
Not only that, but if you think you will be getting those high speeds (that you indicated a preference for) at +- 12 ~ 18 VDC, I think you are being a bit too optimistic. Think bias and heat. Many of these newer chips have a metal heat sink intended to be soldered to the circuit board to act as a larger heat sink for the device. Cool stuff really. Nice solution to the "it's too small to get rid of the heat" issue.
So, what is the common drive level presented to an amplifier input? This is going to be around -20 dB below clipping, right? Being realistic and all that. Keep in mind that these devices are normally rail to rail minus about 200 mV. Not the 2 V less than rail you normally expect from a normal audio op amp.
I was not saying we should move to this type of common rail voltage for general audio work at all. What I was saying was that it was possible to successfully use these devices in audio. BTW, some of these also have very low noise compared to what most products use. These are worth $10 + a piece in production quantities. Like the LMH6624 . I'm not sure if it's what you are looking for, but it's very fast (over a Gigahertz) and very quiet. The link should lead you to a product page. Lot's of different op amps like this listed there.
Again, I am not suggesting that we should use these in audio. I'm only pointing out what reality is. If you poke around, you will see that data conversion products often run at 3.3 VDC, never mind +- 5 VDC. Heat, you know.
-Chris 😉
Chris, I know about the compromises between low voltage fabrication and high voltage fabrication. IF I cannot use at least +/- 15 Volts, then the process is next to useless, to make circuits that would replace what I make in discrete. This is my point.
Hi John,
I agree with you. As I said, I wasn't recommending that we run out and use these for audio. However, you did see the noise rating didn't you? Not much to complain about as far as op amps go.
-Chris
I agree with you. As I said, I wasn't recommending that we run out and use these for audio. However, you did see the noise rating didn't you? Not much to complain about as far as op amps go.
-Chris
Hi John,
More like 50 ohms I'll bet. 😀
But you could always use one of those nifty volume control ICs.
-Chris
More like 50 ohms I'll bet. 😀
But you could always use one of those nifty volume control ICs.
-Chris
Chris, check out the Mar 'Stereophile' with the JC-2 preamp review. Think an IC can do what it does? 😉
Hi John,
Why, no. Why do you ask?
I just threw that out there knowing it was 180° from the direction you normally take. Just kiddin y'all.
I don't get Stereophile - or any other audio magazine. I lost interest completely in the early 80s to be honest with you. That and the equipment reviews became a contest to see who could mis-apply as many descriptive terms as possible, and include more silly details than necessary. What time I do have is spent enjoying my audio system or experimenting on my bench. I do read some professional publications.
The rest of my time is spent lying on the floor with one or two standard poodles close by.
-Chris
Why, no. Why do you ask?
I just threw that out there knowing it was 180° from the direction you normally take. Just kiddin y'all.
I don't get Stereophile - or any other audio magazine. I lost interest completely in the early 80s to be honest with you. That and the equipment reviews became a contest to see who could mis-apply as many descriptive terms as possible, and include more silly details than necessary. What time I do have is spent enjoying my audio system or experimenting on my bench. I do read some professional publications.
The rest of my time is spent lying on the floor with one or two standard poodles close by.
-Chris
I like graphs and measurements that even I can't do easily, if at all. ;-)
Actually, a whole new preamp concept might be +/- 5V ready, but not my traditional stuff.
Actually, a whole new preamp concept might be +/- 5V ready, but not my traditional stuff.
Chris, I do use the +/-5V circuits for instrumentation, I am forced to do it due to collaboration with DSP. Right now it is VCA822 and AD5204. For filters and fixed-gain amplification, i still take the higher voltage AD811, even for lower voltage.
PMA said:
Pavel,
I think a lot of the new breed of fast opamps run equally well on +/-5 as they do on +/-15, isn't it? Or maybe with a very tiny difference?
Jan Didden
janneman said:
A lot of the new opamps do not work at +/-15V, only at +/-5V. Though their parameters are often excellent, the old AD811 has 2500V/us slew rate and output current up to 100mA. The supply voltage is up to +/-18V. Take 2 - 4 in pallel, and you have the best possible buffer.
P.S.: for output stages of instruments, I need high voltage swing into 50 ohm. Sorry for OT.
I don't think that they will release it yet. However, I found it useful that they had access to the $30,000 Audio Precision system, so they could make even deeper measurements than I can. It is all fet, medium feedback, and balanced in and out. It 'measures' better than a CTC Blowtorch, but it would sound quite as good. That is because of the feedback used to get the specs. That's marketing for you. 😉
Hi Pavel,
I'm pretty sure we agree on things. Especially with regard to the newer breed of op amps. DSP chips often only run at 5 VDC and are going to 3.3 VDC. All in the quest for speed and temperature control.
The best buffers may still be discrete. I'm not sure on that, but the idea makes me feel better.
Hi John,
I like working with +- 35 VDC rails. This is for signal stages and buffers. Just my preference at the moment.
-Chris
I'm pretty sure we agree on things. Especially with regard to the newer breed of op amps. DSP chips often only run at 5 VDC and are going to 3.3 VDC. All in the quest for speed and temperature control.
The best buffers may still be discrete. I'm not sure on that, but the idea makes me feel better.
Hi John,
I like working with +- 35 VDC rails. This is for signal stages and buffers. Just my preference at the moment.
-Chris
The AP1 was ageing, and many measurements showed more its limits than that of the measured object. The SYS2722 is a great machine, and it brings the necessary resolution, I am glad that JA has had opportunity to use it.
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