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Old 12th July 2008, 12:48 PM   #1
tryalx is offline tryalx  United States
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Default Oscilloscope, for "debugging" audio signals

Hi,

I would like to ask for some help with choosing an oscilloscope for audio signals, spectral analysis, distortion,... Maybe something with a 50-100 Mhz bandwidth.

I have found some osciloscopes on sale here :

http://www.tequipment.net/OWONEDU5022.html
http://www.tequipment.net/OwonHDS1022M.html

After that I read this article about the sampling artefacts of 8 bit digital osciloscopes :

http://www.picotech.com/application...e_tutorial.html

Mooly, suggested an analog osciloscope.

What kind of osciloscopes are the best, analog, analog/digital, or fully digital?

Thanks, Alexandru
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Old 12th July 2008, 03:41 PM   #2
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go with an analog scope. they're less expensive and there's less that can break inside them.
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Old 12th July 2008, 04:58 PM   #3
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The best scopes are the analog scopes using only switches and potentiometers. Recent cheap analog scopes have menuing systems that make them a PITA to use.

I have an HP1740A and an HP1741A - the '41 is the storage version. The basic specs are 100MHz, dual-trace + trigger view. They are the best scopes I have ever seen, highly recommended if you can find either for a reasonable price.
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Old 12th July 2008, 06:15 PM   #4
Mooly is offline Mooly  United Kingdom
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Hello Alexandru,
Something like this www.farnell.com/datasheets/28792.pdf I think would be ideal for a good all rounder. Gives you an idea what to look for. Try and get at least 20Mhz (Preferably 30 Mhz minimum) bandwidth and go for one with a high accelerating voltage (CRT) as these give a good bright trace. The one in the link above is 2KV which is a bit on the low side but O.K.
Check out Hameg and Tenma for reasonable priced gear. You also need a signal generator-- a function generator would be of more use to you -- covering say 0.1 Hz to at least 1Mhz. These usually give the choice of sine/square/triangle waveform together with other features such as frequency sweeping. Some 'scopes actually have a built in function generator.
Regards Karl
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Old 12th July 2008, 09:23 PM   #5
fotios is offline fotios  Greece
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Default Re: Oscilloscope, for "debugging" audio signals

Quote:
Originally posted by tryalx
Hi,

I would like to ask for some help with choosing an oscilloscope for audio signals, spectral analysis, distortion,... Maybe something with a 50-100 Mhz bandwidth.

I have found some osciloscopes on sale here :

http://www.tequipment.net/OWONEDU5022.html
http://www.tequipment.net/OwonHDS1022M.html

After that I read this article about the sampling artefacts of 8 bit digital osciloscopes :

http://www.picotech.com/application...e_tutorial.html

Mooly, suggested an analog osciloscope.

What kind of osciloscopes are the best, analog, analog/digital, or fully digital?

Thanks, Alexandru
I think the USB2.0 PicoScope 2203 (318$) or 2204 (450$) are very interesting. Don't be confused from the 8bit resolution of their ADC because the sampling rates are 40MS/s and 100MS/s. My DSO Hameg HM502 has also dual ADCs of 8bit / 100MS/s each. You pay the sampling rate in reality. Also they include a basic function generator and Pico offers free of cost the software which includes the FFT analyser. You can download free the software to make an evaluation of these instruments.

Fotios
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Old 12th July 2008, 11:25 PM   #6
tryalx is offline tryalx  United States
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Thanks for the replies!

Quote:
I have an HP1740A and an HP1741A - the '41 is the storage version. The basic specs are 100MHz, dual-trace + trigger view. They are the best scopes I have ever seen, highly recommended if you can find either for a reasonable price.
I have found the description here: http://www.teknetelectronics.com/Dat..._1740A_41A.pdf

I have printed the specs and I will compare them with other brands like Hameg.

Quote:
Check out Hameg and Tenma for reasonable priced gear. You also need a signal generator-- a function generator would be of more use to you -- covering say 0.1 Hz to at least 1Mhz. These usually give the choice of sine/square/triangle waveform together with other features such as frequency sweeping. Some 'scopes actually have a built in function generator.
Definitely a function generator would be very useful. I also like the memory zoom feature to expand the signals. Eventually record the signal to USB drive and use the memory zoom feature.

What else... FFT would be great and the possibility to see very small signals less than 1mV and up to 120V.

I am also interested in visualizing EEG (brain and body) signals and have some filtering functions within the oscilloscope, or PC scope.

Quote:
I think the USB2.0 PicoScope 2203 (318$) or 2204 (450$) are very interesting. Don't be confused from the 8bit resolution of their ADC because the sampling rates are 40MS/s and 100MS/s. My DSO Hameg HM502 has also dual ADCs of 8bit / 100MS/s each. You pay the sampling rate in reality. Also they include a basic function generator and Pico offers free of cost the software which includes the FFT analyzer. You can download free the software to make an evaluation of these instruments.
I also like the idea to be able to see the signals on the PC, which means a big screen and unlimited functionality in software. Yet, having a standalone oscilloscope has its advantages. So maybe an analog oscilloscope with USB connection to the PC and the corresponding software. Finding one with 12 bit resolution probably doubles the price.

It looks like, if I want the above features I will have to spend at least $ 2500 - 3000, which is quite a bit. I guess I need to go over the specs one by one and see which oscilloscope is the most affordable.

Please let me know if any other model/brand comes to your minds.

Thank you everybody, Alexandru
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Old 13th July 2008, 12:11 AM   #7
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i prefer tektronix over HP. the controls are simpler to use and the triggering is rock solid. HP's triggering always seemed to be a bit "mushy". i also prefer tek's 1-2-5 decades over HP's 1-3-5 (just a personal preference)
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Old 13th July 2008, 12:16 AM   #8
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Quote:
Originally posted by unclejed613
i prefer tektronix over HP. the controls are simpler to use and the triggering is rock solid. HP's triggering always seemed to be a bit "mushy". i also prefer tek's 1-2-5 decades over HP's 1-3-5 (just a personal preference)

That's weird. The optimal sequence ought to be 1 - 2.15 - 4.64, so the most reasonable approximation is 1 - 2 - 5. I have never seen a scope with 1 - 3 - 5, so I've obviously never seen a HP.
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Old 13th July 2008, 12:16 AM   #9
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Quote:
i also prefer tek's 1-2-5 decades over HP's 1-3-5 (just a personal preference)
The decades must be model-specific for HP, the 1740A has 1-2-5 decades.
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Old 13th July 2008, 12:23 AM   #10
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By the way, has anybody tried these PC scopes which com in various sampling rates up to at least 250 MSPS and at fairly reasonable prices. They appear everywhere on the net, not least on ebay.

http://www.made-in-china.com/showroo...DSO-2090-.html

(Sorry for linking to a webshop, but I could't find a neutral site describing them. I do not mean to promote this shop or any other seller. )
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