Author Topic: high quality sine wave ?  (Read 4167 times)

0 Members and 1 Guest are viewing this topic.

Online f5r5e5d

  • Frequent Contributor
  • **
  • Posts: 330
Re: high quality sine wave ?
« Reply #25 on: March 19, 2017, 11:22:55 AM »
"no ceramic" is painting with too broad a brush

NP0 is a low k ceramic dielectric that gives near perfect distortion performance excepting for some leaded types possibly having bad end metallization/lead attachment issues

Mica is a very variable natural material that can be as poor as better Mylar

and Mylar/Polyester is the worst common plastic film dielectric - Polypropylene is better, Polystyrene measures best for low audio frequency distortion

Cyril Bateman's "Capacitor Sound" series did serious measurements, Bruce Hofer of Audio Precision gives simailar recommendations in his seminars/presentations

the http://www.diyaudio.com/forums/equipment-tools/205304-low-distortion-audio-range-oscillator.html has many measurements, references, commentary if you really want to get into a analog oscillator build


I would just recommend a decent soundcard like the ESI [email protected]

from the diyAudio thread, showing 24 bit mode may be necessary to even see the distortion:
« Last Edit: March 19, 2017, 07:27:01 PM by f5r5e5d »
 

Offline RGK

  • Contributor
  • Posts: 24
Re: high quality sine wave ?
« Reply #26 on: March 21, 2017, 01:45:40 PM »
Very nice.  Did you make your own board or get it from Janascard?  I've made an inquiry to them.

BK

*forgot to quote - remark is WRT to JoeN Janascard oscillator project*

I laid it out in DipTrace and ordered it from OSHPark.  I can't say my layout is an expert layout, I simply tried to make sure all the parts were laid out intelligently and as closely as possible to their dependent parts and used a four layer board with three of the layers for the three rails planes, bottom one (-15V) with some signals too.  Power input connector was one I already had, SMA output was my choice.  Diodes, resistors, zeners, pots, capacitors were parts I chose myself.  On the Linear sheet Jim Williams says to use ceramic capacitors nowhere, so I did what he advised, using only electrolytic and PET capacitors, and the 47pF capacitor is mica.  Someone else might design with different parts for those, the PDF didn't specify specific exact passive parts and connectors.

Thanks for that and also evb149 for bringing it up.  Bought the oscillator PCB and also the notch filter PCB from Janascard.  Will update after it arrives to compare layout.  So I guess I'll end up with a state-of-the-art sine wave after all....

BK
 

Online rsjsouza

  • Super Contributor
  • ***
  • Posts: 1694
  • Country: us
    • Vbe - vídeo blog eletrônico
Re: high quality sine wave ?
« Reply #27 on: March 21, 2017, 01:59:35 PM »
For ultra-pure sinewave generation I drool over the Krohn Hite 4402... Someday I will get one.  :-/O
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline JoeN

  • Frequent Contributor
  • **
  • Posts: 927
  • Country: us
  • We Buy Trannies By The Truckload
Re: high quality sine wave ?
« Reply #28 on: March 21, 2017, 02:00:10 PM »
Bought the oscillator PCB and also the notch filter PCB from Janascard.  Will update after it arrives to compare layout.  So I guess I'll end up with a state-of-the-art sine wave after all....

BK

I never saw that they offered it for sale.  I checked their site again and I still don't see it.  http://www.janascard.cz/aHome.html   Is it offered somewhere else or did you simply ask them?
Have You Been Triggered Today?
 

Offline RGK

  • Contributor
  • Posts: 24
Re: high quality sine wave ?
« Reply #29 on: March 21, 2017, 02:51:03 PM »
Bought the oscillator PCB and also the notch filter PCB from Janascard.  Will update after it arrives to compare layout.  So I guess I'll end up with a state-of-the-art sine wave after all....

BK

I never saw that they offered it for sale.  I checked their site again and I still don't see it.  http://www.janascard.cz/aHome.html   Is it offered somewhere else or did you simply ask them?

Yep, inquired by email and heard back promptly.  $33 paypal later boards are on the way.  I'm not skilled enough to do my own PCB layout!

BK
 

Offline RGK

  • Contributor
  • Posts: 24
Re: high quality sine wave ?
« Reply #30 on: March 21, 2017, 02:56:07 PM »
For ultra-pure sinewave generation I drool over the Krohn Hite 4402... Someday I will get one.  :-/O

Nice!

BK
 

Offline TimFox

  • Frequent Contributor
  • **
  • Posts: 800
  • Country: us
  • Retired, now restoring antique test equipment
Re: high quality sine wave ?
« Reply #31 on: March 22, 2017, 06:26:48 AM »
Almost as good as the K-H 4402 is the -hp- 339A THD analyzer, which includes a low-distortion generator.  The residual distortion in mine measures about 0.002% (-94 dB) which should be good enough for any normal applicatioin.  Units such as the 339A have the advantage that the analyzer tunes directly to the internal oscillator frequency, and will lock to an external oscillator when the frequency is approximately correct.  Also, the indicated fraction of distortion scales automatically to the input signal.  You can learn a lot about the DUT by analyzing the distortion output signal, which has the fundamental removed.
 

Offline RGK

  • Contributor
  • Posts: 24
Re: high quality sine wave ?
« Reply #32 on: March 22, 2017, 10:53:36 AM »
Will a good oscillator + the HP 334A be just as good as the HP 339A?  I picked up two of the former, which set me on a path for a decent 1kHz sinewave reference.  Looking at the distortion output with fundamental removed was definitely part of my plan.

How does the K-H 4400 compare to the K-H 4402?

BK
 

Offline Audioguru

  • Frequent Contributor
  • **
  • Posts: 911
  • Country: ca
Re: high quality sine wave ?
« Reply #33 on: March 22, 2017, 12:24:32 PM »
Check out the MAX7400 series.

https://datasheets.maximintegrated.com/en/ds/MAX7400-MAX7407.pdf

Rob
I made a sinewave that had 10 steps and about 6% distortion with a CD4018 and a few resistors. Then I filtered it with National Semiconductor switched capacitor filter ICs that had 8 Butterworth orders and the output distortion was so low that it could barely be measured.

Guys have taken a buzzer sound and filtered it with switched capacitor filters and ended up with pretty good sinewaves.
 

Online nfmax

  • Frequent Contributor
  • **
  • Posts: 556
  • Country: gb
Re: high quality sine wave ?
« Reply #34 on: March 28, 2017, 03:01:17 AM »
Almost as good as the K-H 4402 is the -hp- 339A THD analyzer, which includes a low-distortion generator.  The residual distortion in mine measures about 0.002% (-94 dB) which should be good enough for any normal applicatioin.  Units such as the 339A have the advantage that the analyzer tunes directly to the internal oscillator frequency, and will lock to an external oscillator when the frequency is approximately correct.  Also, the indicated fraction of distortion scales automatically to the input signal.  You can learn a lot about the DUT by analyzing the distortion output signal, which has the fundamental removed.
The oscillator part of the 339A was made as a standalone oscillator model 239A - quite a small dinky little thing, and no fan so they tend to be in immaculate condition internally. I have one and it works nicely, but they are very rare on the secondhand market. As well as low distortion, it has good level setability right down to sub 1mV, and it the output is isolated from ground - two essential attributes for a low distortion audio source.
 

Offline Electro Fan

  • Super Contributor
  • ***
  • Posts: 1674
Re: high quality sine wave ?
« Reply #35 on: March 28, 2017, 04:50:15 AM »
 

Offline TimFox

  • Frequent Contributor
  • **
  • Posts: 800
  • Country: us
  • Retired, now restoring antique test equipment
Re: high quality sine wave ?
« Reply #36 on: March 30, 2017, 10:06:41 AM »
Will a good oscillator + the HP 334A be just as good as the HP 339A?  I picked up two of the former, which set me on a path for a decent 1kHz sinewave reference.  Looking at the distortion output with fundamental removed was definitely part of my plan.

How does the K-H 4400 compare to the K-H 4402?

BK

The residual distortion in the 334A is not as good as in the 339A.  Both the 333A and 334A will auto-tune the frequency and phase when the manual tuning and phase knobs are close to the correct values for the external oscillator.  Another advantage of the 339A is that the distortion value indicated scales automatically to the input level, while the 334A/333A require a manual adjustment to 100%.
 
The following users thanked this post: RGK


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf