1kHz Reference source

[lucian]

When making measurements of your own you never now the primary source of you harmonics. There are very cheap 1kHz source which claim very low distortion and would be nice to test the ADC stage.

Anyone experience with this? Is it worth it?

https://www.ebay.de/itm/Assembled-L...rentrq:e5d3d29f16d0a9cb7194420fffebc692|iid:1

 

[pozz]

Distortion less than 0.1% (-60dB) at 1kHz? I'd say no.

 

[amirm]

Hard to tell what the distortion spec is:

0.1% is horrible. -124 dB is exceptional (0.0000631%).

 

[lucian]

Yeah - that what I saw too. I saw this thread but could not find the Victors oscillator on ebay anymore. So I was hoping this would be a cheap working Chinese copy.

@amirm
keen to measure it

https://www.eevblog.com/forum/testgear/looking-for-ultra-low-distortion-1khz-sine-generator/

 

[amirm]

Yeh, I searched hi and lo but could not find Victor's anymore a while back. And sure, if you want to drop ship it to me, I can measure it. Just start a conversation with me and we can take it from there.

 

[scott wurcer]

Yeh, I searched hi and lo but could not find Victor's anymore a while back. And sure, if you want to drop ship it to me, I can measure it. Just start a conversation with me and we can take it from there.

AFAIK Victor still takes orders personally, the current version is -140dB or so. It does require a 36V DC supply that the user provides.

 

[JohnYang1997]

I have used that one. With tuning the pot, you can eliminate the 2nd order harmonics completely. But 3rd will be around 0.004%. If that's good enough for you, then it's good. If not, then try something else.

 

[lucian]

AFAIK Victor still takes orders personally, the current version is -140dB or so. It does require a 36V DC supply that the user provides.

do you have a contact? Couldn't find anything else than this threat.

 

[lucian]

I have used that one. With tuning the pot, you can eliminate the 2nd order harmonics completely. But 3rd will be around 0.004%. If that's good enough for you, then it's good. If not, then try something else.

Thx, at least that would be enough to verify the limit of the ADC stage.

 

[scott wurcer]

Victor is a member at DIYAudio user name vicnic you can see for yourself.


The yellow trace is the output of the 1kHz notch, input is Viktor's 1kHz oscillator. The notch dept is about 44dB, and there is no distortion visible. The noise floor at 2kHz is ~-138dB and at 3kHz ~-144dB.
The red trace is with the AP generator as input. Here we clearly see the residual of the AP generator, at ~-136dB and 3rd at ~-138dB.
If I do a loopback I get these same numbers for the AP. So the concept seems to work and I can already show that Victor's oscillator is better than the AP.

 

[PaulD]

do you have a contact? Couldn't find anything else than this threat.

I think you can find his oscillator here http://www.janascard.cz/aj_Zakazkova_vyroba.html#oscil

 

[Wombat]

Yeh, I searched hi and lo but could not find Victor's anymore a while back. And sure, if you want to drop ship it to me, I can measure it. Just start a conversation with me and we can take it from there.

Maybe the same Victor? https://www.eevblog.com/forum/testgear/looking-for-ultra-low-distortion-1khz-sine-generator/ Scroll down a little.

 

[Wombat]

EDN: https://www.edn.com/electronics-news/4389675/Low-distortion-oscillator-tests-measurement-circuits

Note the references, also.

This is sourced from @PaulD 's link, above.

 

[PaulD]

EDN: https://www.edn.com/electronics-news/4389675/Low-distortion-oscillator-tests-measurement-circuits

Note the references, also.

This is sourced from @PaulD 's link, above.

That is the article I first saw, I think it's for sale from the link I posted, and it's cheap!

 

[Rja4000]

could not find Victor's anymore

I purchased one a few weeks ago.
Still have to build a proper PS for it though.
I tested it with direct power from 4x9V cells, but that's a bit disappointing.
I guess it would perform better with a proper supply.

 

[Rja4000]

AFAIK Victor still takes orders personally, the current version is -140dB or so. It does require a 36V DC supply that the user provides

He does.

Have a look at this thread and contact vicnic
https://www.diyaudio.com/forums/equ...ow-distortion-audio-range-oscillator-774.html

Some interesting people post there:
Jan Didden is the guy building the AutoRanger, HPW wrote the measurement software with the same name (HpW-Works Analyzer),...

 

[Rja4000]

I think you can find his oscillator here http://www.janascard.cz/aj_Zakazkova_vyroba.html#oscil

I think this one is different

 

[Rja4000]

Just performed some measurements on Victor generator 1kHz

Note that this is not measured in ideal conditions: the generator is directly fed by 4x9V batteries here.
I think one may expect (much?) better results from properly regulated power supply.

Not too bad though
SINAD seems to be limited by noise.
I'm in Belgium, so 50Hz peak is linked to mains influence.

Black= RME ADI-2 Pro fs DAC signal, for reference (Unbalanced out, +13dBu range, -2.59dBFS level)
Red= Victor's 1kHz generator

ADC= RME ADI-2 Pro fs, Unbalanced inputs, +13dBu range
Victor oscilator level set to maximum
Measured with Virtins Multi Instrument 3.8 @48kHz 24 bits, FFT Window size 32768, Kaiser 6
(Note that there may be more spectral leakage with Victor's signal.)

Distortion figures:

A=RME, B=Victor

Highest distortion is H3, with around -116dB vs signal, which pretty much sets the level of THD (-115.6dB)
I've read somewhere that, typically, H3 will raise when powered from battery cells directly, due to their high internal resistance.
Other harmonics are all <-130dB, which make them hard to differentiate from the ADC distortions.

I paid around 50€ for the generator.

 

[scott wurcer]

I think this one is different

Yes that one is photo-resistor based, Victor's is FET based. That article references the one we did in 1994 which was Blackmer VCA based.

I quoted Jan's measurements of Victor's oscillator above which added nothing to the floor of his AP.

 

[Rja4000]

I quoted Jan's measurements of Victor's oscillator above which added nothing to the floor of his AP.

Could you also publish the link, if you have it?

Do you think it will improve with a proper PS?