What's this test equipment for??

[hugobross]

Hi all,

I've got here some kind of test equipment of Spectral Dynamics Corporation. It's called a 'Voltmeter / frequency log converter' , model SD112-1. It has 2 large analog meters(volts + dB) on it, 2 inputs (BNC) and 2 log DC outputs(BNC).
Switches at front:
2 x input range(volts): DC 1 - DC 10 - DC 100 - AC 1 - AC 10 - AC 100
2 x meter multiplier: .001 - .01 - .1 - 1
1 x voltmeter/log conv AC RESPONSE: slow - med - fast
+ Y-cal: chan1(-10dB) - OPER - chan2(-10dB)
1 x log freq. conv. RANGE (Hz): 5-5K - 10-10K - 20-20K
+ X-cal: lin - oper - upper

Does anyone know what this can be used for??

Thanks,

HB.

[paulb]

I think it's just an AC voltmeter that has a log scale.

[vpharris]

Did you look at their website? I think you can make some guess from doing so. Or you can send them an email.
http://www.spectraldynamics.com/index.htm

[hugobross]

thanks,

Yes, I've visited their site but nothing about this model. I'll send them a mail and ask for further details.

thanks, HB.

[Pjotr]

Hi,

It is a logarithmic volt meter/converter and a logarithmic frequency meter/converter. Instead of displaying in a linear way it displays logarithmically. That way you can see a large range with relative accuracy without range switching. From the description it is a frequency meter with analog readout too. The “log” outputs on the back are intended to drive a pen-plotter. Long time ago I used a comparable one from Hewlett Packard. I used it for making dB plots in combination with a RMS meter. But since your one has also an AC capability you can probably use it directly for (audio) level measurements. Connect a sine generator to it and check to what frequency it will go. If you connect it to the frequency meter too you can readout the frequency. If you now connect the log outputs to a analog X-Y plotter you can make nice frequency response plots with it.

Got it?

They usually need a long warm-up time because most of this kind of meters tends to drift a lot with temperature.

I personally, I'll stick with a soundcard based audiomeasurement system nowadays

[hugobross]

thanks, Pjotr!!!!!!

[JDeV]

Originally posted by Pjotr


I personally, I'll stick with a soundcard based audiomeasurement system nowadays

Where can I find out more about doing this, is it possible to diy if soundcard is available?

[Pjotr]

Originally posted by JDeV


Where can I find out more about doing this, is it possible to diy if soundcard is available?

Hi,

Good software is SpectraLab. It is well established, but be prepared: It is huge expensive (far over $1000) and intended for the professional.

I myself use SampleChampion (what a name) from Purebits.com. The user interface can be better and it is somewhat buggy. But this doesn’t bother me much. It is a very powerful engine with loads of features (FFT up to 256k points). It uses MLS (maximum length sequence) techniques for response measurements although you can use sweeps too with some imagination. E-mail support is very good. Price is just under 300 EU and is definitely worth the money. With a Soundblaster Live1024, you can do already a lot if you stick to 48 kHz sampling rate. I am using a M-audio 24/96 soundcard and the the combo serves me very well. Attached is a screen capture of the distortion of the soundcard itself at 24bit/48kHz at –10dB full scale, input and output were connected directly. The picture is an averaging of 64 measurements. Without averaging the noise floor is about 20 dB higher.