Hi everybody,
I need some help here.
I would be interested in the audio precision system one 222G + dsp with almost full options.
Then I called Ap and they discouraged me from getting this one because of the age, plus gpib port won't allow me to use the ApWin sw only with an additional $650 extra interface; plus they told me that if the dsp goes down which is very possible I can kiss goodbye to the instrument.
They rather suggest the analogue version.
But I am interested on a precise, flexible instrument pc interfaceble where I can plot graphs elaborate data and stuff.
So they suggestede to get the apx515 or something like that.
The only problem is that this instrument is a little over budget (6.2k).
I would like to know from users of Ap what are some thoughts in this regard and how they evaluate Ap system one with gpib port.
I am not set with gpib interface nor have I ever work or play around with one.
Any suggestion will be very welcome.
For now I am using the sound technology 1700B with the external low noise/distortion signal generator and a nice sound card to interface the FFT of the signal but I wouldn't disregard having just one compact, flexible and precise machine.
Thanks everybody for your attention.
I need some help here.
I would be interested in the audio precision system one 222G + dsp with almost full options.
Then I called Ap and they discouraged me from getting this one because of the age, plus gpib port won't allow me to use the ApWin sw only with an additional $650 extra interface; plus they told me that if the dsp goes down which is very possible I can kiss goodbye to the instrument.
They rather suggest the analogue version.
But I am interested on a precise, flexible instrument pc interfaceble where I can plot graphs elaborate data and stuff.
So they suggestede to get the apx515 or something like that.
The only problem is that this instrument is a little over budget (6.2k).
I would like to know from users of Ap what are some thoughts in this regard and how they evaluate Ap system one with gpib port.
I am not set with gpib interface nor have I ever work or play around with one.
Any suggestion will be very welcome.
For now I am using the sound technology 1700B with the external low noise/distortion signal generator and a nice sound card to interface the FFT of the signal but I wouldn't disregard having just one compact, flexible and precise machine.
Thanks everybody for your attention.
You can get the new Stanford Research audio analyzer pretty close to your budget.
Audio Analyzer - SR1
SRI is very highly regarded for their scientific and measurement equipment. I think Janneman saw the SR1 in action at a trade show.
Audio Analyzer - SR1
SRI is very highly regarded for their scientific and measurement equipment. I think Janneman saw the SR1 in action at a trade show.
I have an AP S1 + DSP. It's a nice instrument but I would not buy it today. Hardware-wise I think it is still at least as good as an APx515; these are more production-oriented and not really the very highest resolution.
The AP S1 software is, to say the least, very user unfriendly and not up to speed with the modern instrumentation applications. It's a DOS port to windows and it's structure still is DOS-wise. Also, APWIN (which runs the AP S1) doesn't run on W7, doesn't run on 64bits systems and is no longer supported. Even if you get an S1 with the original APIB interface card you need a PCI slot so using it on a laptop is out. This is a good product but with dated h/w and s/w.
I would get the best soundcard you can get and a good analysis software.
The AP S1 works up to 200kHz and that's the weak point of a sound card; even with 192kHz sampling you'r limited to 90kHz analysis or so.
If I would have several $ 1000's to spend I would see if I can get an SR1. Alternatively, take a look at the LinearX LX700 system, which fills a middle ground.
jan didden
Thank you very much for you input.
You have been really useful and precise.
I have 2 questions then
1) how much would it be a lx700 if I were to get one with same features of Ap 1 but up to date he and sw?
2) what is the BEST souncard you would recommend? I know it is limited to 90khz but if I can get reliable and calibrated results up to 90khz and precision up to 0.05db that would be all I need. Is it possible to have such a precision and low noise with a sound card? The biggest problem I found so far with soundcard system is the noise if the generator and dynamic range I.e. measurements are susceptible to in/out level. I have a low noise gen but if I would like to get a frequency response I would have to sweep it manually which is not feasible for time response and flat response of the generator especially if trying to measure a high gain device such as Phono stage.
You have been really useful and precise.
I have 2 questions then
1) how much would it be a lx700 if I were to get one with same features of Ap 1 but up to date he and sw?
2) what is the BEST souncard you would recommend? I know it is limited to 90khz but if I can get reliable and calibrated results up to 90khz and precision up to 0.05db that would be all I need. Is it possible to have such a precision and low noise with a sound card? The biggest problem I found so far with soundcard system is the noise if the generator and dynamic range I.e. measurements are susceptible to in/out level. I have a low noise gen but if I would like to get a frequency response I would have to sweep it manually which is not feasible for time response and flat response of the generator especially if trying to measure a high gain device such as Phono stage.
2 channels would be better.
100KHz bandwidht would be minimum requirement.
106-110dB S/N
Distortion floor <0.001%
I would like the PC interface capabilities to be able to see the FFT, frequency response, distortion along bandwidth.
no need for digital audio capabilities now.
I have looked through the LX and looks like it would cost over 6K to build something similar but I will double check that, so it would be pretty costly.
Can you tell me if you have any experience comparing your Ap system one with an high end soundcard based system?
If so, what are the main disadvantages and/or advantages you see usign a soundcard versus system one?
In that case what racommendation do you have for soundcard?
thanks.
100KHz bandwidht would be minimum requirement.
106-110dB S/N
Distortion floor <0.001%
I would like the PC interface capabilities to be able to see the FFT, frequency response, distortion along bandwidth.
no need for digital audio capabilities now.
I have looked through the LX and looks like it would cost over 6K to build something similar but I will double check that, so it would be pretty costly.
Can you tell me if you have any experience comparing your Ap system one with an high end soundcard based system?
If so, what are the main disadvantages and/or advantages you see usign a soundcard versus system one?
In that case what racommendation do you have for soundcard?
thanks.
With a soundcard as compared to an AP, you'll never be sure that the noise you're seeing is from the device you're testing rather than from the PC. That's because the AP has taken pains to build in isolation for its outputs. To make the best use of a soundcard, you'd need to have some kind of interface box providing the isolation if you hope to get repeatability at low levels. The soundcard would need balanced inputs and outputs to connect to this box.
Hi,
Thanks for your input as well.
I don't understand what you mean by isolation box that has to be balance.
Are you talking about isolate ground with opto or transformer?
That wouldn't fix the noise at the output of the souncard nor the noise floor of internal input converter filter ect..
Can you explain better what you mean or give an example?
I do usually avoid the generator of the soundcard and use a low noise sound technology external signal gen.
But again many measurements are not repeatable and vary with signal level.
Thanks for your input as well.
I don't understand what you mean by isolation box that has to be balance.
Are you talking about isolate ground with opto or transformer?
That wouldn't fix the noise at the output of the souncard nor the noise floor of internal input converter filter ect..
Can you explain better what you mean or give an example?
I do usually avoid the generator of the soundcard and use a low noise sound technology external signal gen.
But again many measurements are not repeatable and vary with signal level.
The AP's signal generator is isolated via a transformer, so it truly floats. When a soundcard generates a signal, that will come along with some PC noise (generally its common mode noise, so exists fairly equally on both the ground and signal connections). If this is used to test some battery powered or isolated piece of kit there's not a problem. The potential noise problems come when another mains powered device is tested - then there's a loop for the noise currents to travel around, via the capacitance of the mains transformer in that device.
An isolation box would also have a mains supply, so to avoid problems with signals getting into the link between the PC and the isolation box, it would need to have a balanced input and the soundcard a matching balanced output.
Have I made the situation any clearer now?
<edit> Ideally the isolation box would have attenuators built in (for the output) and gain (for the input), and provide a true balanced input too. Then the link between the PC and the box would be able to run at full signal level for best SNR. Hopefully, the attenuators and gain would be under control of the PC via an isolated digital interface. There, I've given a potential designer/manufacturer of that box a spec
An isolation box would also have a mains supply, so to avoid problems with signals getting into the link between the PC and the isolation box, it would need to have a balanced input and the soundcard a matching balanced output.
Have I made the situation any clearer now?
<edit> Ideally the isolation box would have attenuators built in (for the output) and gain (for the input), and provide a true balanced input too. Then the link between the PC and the box would be able to run at full signal level for best SNR. Hopefully, the attenuators and gain would be under control of the PC via an isolated digital interface. There, I've given a potential designer/manufacturer of that box a spec
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Hi,
So you are assuming that the noise is mainly common mode, which might be true or not.
In the case it is, then a CMC should be able to manage that.
Nevertheless it looks like you are talking about having an active box with a certain gain BW.
This in my opinion adds up noise and distortion and might alter the bandwidth as well.
Nonetheless I might not fully understanding your idea, anyways I am not looking for something else to say but I am looking for test equipment to make reliable measurements on what I make.
I still say that your idea might be valuable and thank you for your input.
So you are assuming that the noise is mainly common mode, which might be true or not.
In the case it is, then a CMC should be able to manage that.
Nevertheless it looks like you are talking about having an active box with a certain gain BW.
This in my opinion adds up noise and distortion and might alter the bandwidth as well.
Nonetheless I might not fully understanding your idea, anyways I am not looking for something else to say but I am looking for test equipment to make reliable measurements on what I make.
I still say that your idea might be valuable and thank you for your input.
A CMC attenuates noise over a fairly narrow band of frequencies. The ones I've looked at start acting around 100kHz and are good for a decade or two beyond that. After 10MHz their self-capacitance tends to swamp their series inductance. Noise from PCs tends to have contributions way beyond 10MHz. At best a CMC might give 40-50dB of attenuation.
Yes you're correct, an active box will add noise and distortion but its not that difficult to keep its noise and distortion contributions below that of the ADC and DAC. The bandwidth you said you were interested in is up to 90kHz so that's no problem.
Yes you're correct, an active box will add noise and distortion but its not that difficult to keep its noise and distortion contributions below that of the ADC and DAC. The bandwidth you said you were interested in is up to 90kHz so that's no problem.
Yes that's true, in general. Yet, some very good sound-card based hardware like Bob Cordell's interface box for the Juli@ card, and another one by Pete Millett are avaiable diy.
I think the AP will in the end get the most clean noise floor, BUT the software you can get (some for free) for sound-card based stuff is lightyears ahead of AP and will run on today's OSs.
If you just start out with this type of equipment it would make sense to spend a couple of 100 $ on a good soundcard system. Then, when you actually use it and find what you like/dislike need/don't need, you can much better decide what it really is you want. Chances are that that (soundcard system) is all you DO need.
jan didden
I do already have a M-Audio proline 610 sound card.
I know limitations already.
Number one is the signal generator but that I get by using the sound technology external generatoru which achieves <0.001% distorion and low noise floor.
Number two is the repeatably of the measurements, depends upon the usage of the memory on your PC and even if AV is shut down and other things, still there is variation on the FFT due to the internal noise caused by program in the background
Number 3 is the accuracy of the measurement. Actually how real the measurement is and how credible is the TDH number it gives you.
I am using spectra plus.
It is a nice SW but again you will never know how calibrated the system is.
Now it is the second time I see this Juli@ card.
Is it a special one? lower noise floor better performance?
What is the interface that Bob Cordell makes? Could you please point that out?
Is there anybody using this set up and actually succeding, and ending up prefering a PC based system rather than an Audio precision System one?
I mean there is a factor of 2 or 3 involved when talking about a system one and a more modern Ap, so it is not trivial at all.
I do also have access at work at the top level Agilent Spectrum analyzer that I use on the EMI chamber for measurements on the projects I lead and also to a 25K tektronix mixed signal Oscilloscope and next week under my request for a project I am developing the company is going to get a network analyzer.
So I do have access to all these instruments but they are not mine of course and I would not take the chance to bring them back home on the weekend and risk something happens to them aahahah it is almost an house pricewise.
So I would like to get a decent instrumentation but when I want to make special measuremets I can always bring my stuff over there and do iut after work.
I know limitations already.
Number one is the signal generator but that I get by using the sound technology external generatoru which achieves <0.001% distorion and low noise floor.
Number two is the repeatably of the measurements, depends upon the usage of the memory on your PC and even if AV is shut down and other things, still there is variation on the FFT due to the internal noise caused by program in the background
Number 3 is the accuracy of the measurement. Actually how real the measurement is and how credible is the TDH number it gives you.
I am using spectra plus.
It is a nice SW but again you will never know how calibrated the system is.
Now it is the second time I see this Juli@ card.
Is it a special one? lower noise floor better performance?
What is the interface that Bob Cordell makes? Could you please point that out?
Is there anybody using this set up and actually succeding, and ending up prefering a PC based system rather than an Audio precision System one?
I mean there is a factor of 2 or 3 involved when talking about a system one and a more modern Ap, so it is not trivial at all.
I do also have access at work at the top level Agilent Spectrum analyzer that I use on the EMI chamber for measurements on the projects I lead and also to a 25K tektronix mixed signal Oscilloscope and next week under my request for a project I am developing the company is going to get a network analyzer.
So I do have access to all these instruments but they are not mine of course and I would not take the chance to bring them back home on the weekend and risk something happens to them aahahah it is almost an house pricewise.
So I would like to get a decent instrumentation but when I want to make special measuremets I can always bring my stuff over there and do iut after work.
This kind of information would be very useful for those threads that happen from time to time about how the same audio sounds different when played out with different software. Would you be able to give some indication of the degree of variation you experience?
Well you *always* get variations in repeated measurements. Like Abrax says, how big are they?
Anyway, it seems you don't have a clear idea of what minimum specs you need. You keep referring to AP and if you want that just buy it.
But can you give some numbers of what you really want?
Bob Cordell's interface is described in his book and also here in the forum, but I can't tell you exactly where. Needs some searching I guess.
There's more threads here about the results of soundcards and I am often impressed as they come very close and sometimes better than AP (there, I've said the A-word too ).
jan didden
Anyway, it seems you don't have a clear idea of what minimum specs you need. You keep referring to AP and if you want that just buy it.
But can you give some numbers of what you really want?
Bob Cordell's interface is described in his book and also here in the forum, but I can't tell you exactly where. Needs some searching I guess.
There's more threads here about the results of soundcards and I am often impressed as they come very close and sometimes better than AP (there, I've said the A-word too
).jan didden
the difference is not acceptable.
I am used to precise instruments that give you repeatable results as expected anytime, but unfortunately I can't efford instruments of such a level.
I know exactly what I want of course and the original thread was intended to be whether a audio precision system one would be a convenient purchase at 2.5K and with the GPIB port I could do graphs like the one you see on for instance Stereophile magazine (I know they have borrowed the top level from Ap so the accuracy is of course hogh)
In matter of precision and specs, I am looking for something that is
generator 0.01dB flat over 50KHz at least
TDH+N <110dB i.e. analizer distortion measurements <0.001%
residual noise <115dBu
2channels is preferable, but one is fine as well as I don't need to analyze both ch at the same time
possibility of tracing frecuency response, phase resposne, distortion over the band, FFT, S/N noise A-weighted and non-weighted.
Bandwidht of at least 100KHz would be good, more is better of course.
That's is "all" I need .
I am used to precise instruments that give you repeatable results as expected anytime, but unfortunately I can't efford instruments of such a level.
I know exactly what I want of course and the original thread was intended to be whether a audio precision system one would be a convenient purchase at 2.5K and with the GPIB port I could do graphs like the one you see on for instance Stereophile magazine (I know they have borrowed the top level from Ap so the accuracy is of course hogh)
In matter of precision and specs, I am looking for something that is
generator 0.01dB flat over 50KHz at least
TDH+N <110dB i.e. analizer distortion measurements <0.001%
residual noise <115dBu
2channels is preferable, but one is fine as well as I don't need to analyze both ch at the same time
possibility of tracing frecuency response, phase resposne, distortion over the band, FFT, S/N noise A-weighted and non-weighted.
Bandwidht of at least 100KHz would be good, more is better of course.
That's is "all" I need
.
the difference is not acceptable.
I am used to precise instruments that give you repeatable results as expected anytime, but unfortunately I can't efford instruments of such a level.
I know exactly what I want of course and the original thread was intended to be whether a audio precision system one would be a convenient purchase at 2.5K and with the GPIB port I could do graphs like the one you see on for instance Stereophile magazine (I know they have borrowed the top level from Ap so the accuracy is of course hogh)
In matter of precision and specs, I am looking for something that is
generator 0.01dB flat over 50KHz at least
TDH+N <110dB i.e. analizer distortion measurements <0.001%
residual noise <115dBu
2channels is preferable, but one is fine as well as I don't need to analyze both ch at the same time
possibility of tracing frecuency response, phase resposne, distortion over the band, FFT, S/N noise A-weighted and non-weighted.
Bandwidht of at least 100KHz would be good, more is better of course.
That's is "all" I need
That's a $ 100 soundcard and $ 50 software. And, as you said, you can do the serious stuff at work
jan didden
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