Low-distortion Audio-range Oscillator

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#4,222
JohnW said:
Sam,

I requested these 5V reed relays as samples about 5 years ago, so I need to reestablish contact with the company.

They are a common form factor - with the price about US0.30 to US$0.40 each.

https://dl.dropboxusercontent.com/u/86116171/SIL Reed Relay 5V.jpg

I'll be back in Asia at the end of the month so can ask sourcing dept to follow up and get the latest pricing - I'll be using them on a new DAC and AMP design so it not a problem to order extra Qtys. if the price is good.
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I have a ton of those relays in my loft, if anyone is interested.
 
#4,224
Samuel Groner said:
Some time back I noted that they have about 10 dB lower distortion at 10 Hz (http://www.diyaudio.com/forums/equi...n-audio-range-oscillator-353.html#post3849168). Looking at my current set of measurement data the typical difference might be even shallower, say 5 dB.

Samuel
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Samual,

Thanks for the link, sorry this thread is so long I did not read through it all.

Interesting that the Vishays Bulk foils are still better then the MELFs, so this does not explain the differences in Bass I noted.

The DAC design I'm working on has dual PCB footprint for MELF / Bulk foils so it will be interesting to seriously compare them...
 
#4,226
Brief update on my oscillator project: I have now about one-third of the PCB assembled--the on-board voltage regulators, output drivers, part of the output attenuators, control logic and relay drivers.

I've made a few silly mistakes (one error in the solder mask, wrong footprint for a logic IC and some swapping of relay control lines) which were easy to fix but will require another PCB revision in case I'll offer boards.

So far everything well regarding signal integrity; the noise contribution of the output drivers (balanced output, 22-22k Hz measurement bandwidth) is below -133 dB worst-case, and THD completely dominated by the AP SYS-2722 I'm using (individual harmonics < -130 dB in the 100-5k Hz range).

Samuel
 
#4,229
Samuel Groner said:
Brief update on my oscillator project: I have now about one-third of the PCB assembled--the on-board voltage regulators, output drivers, part of the output attenuators, control logic and relay drivers.

I've made a few silly mistakes (one error in the solder mask, wrong footprint for a logic IC and some swapping of relay control lines) which were easy to fix but will require another PCB revision in case I'll offer boards.

So far everything well regarding signal integrity; the noise contribution of the output drivers (balanced output, 22-22k Hz measurement bandwidth) is below -133 dB worst-case, and THD completely dominated by the AP SYS-2722 I'm using (individual harmonics < -130 dB in the 100-5k Hz range).

Samuel
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😎🙂



-RNM
 
#4,230
For anyone interested I have just scanned the schematics to the Krohn Hite 4000 series ultra low distortion oscillators. The design dates from 1962 and they were pretty much the lowest distortion and most stable RC oscillators until much later. The AGC is really interesting and really fast. it does limit the distortion adding a small glitch as part of how it works. These oscillators go down to pretty low frequencies - .001 Hz.

PM me with your e-mail and I'll send them - 4.5 MB zip file.
 
#4,237
davada said:
I received an Email from Dick Moore's wife Robbin today informing me that our good friend Dick died Saturday of complications from 75 years of diabetes.
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I am so very, very sorry to hear this. Dick was a generous gentleman who contributed greatly over a period of many years. He has been an inspiration to all of us.

My prayers are with his wife and family.

Sadly,
Bob
 
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