Low-distortion Audio-range Oscillator

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#3,181
It seems this subject is of interest everywhere on the planet and it was just brought to my attention that such an analyzer has been done and written up. It takes A-P and B.Cordell's ideas and comes up with -120db meter readings and uses relays in place of switches etc. Check it over at "Who wants to build a Distortion analyzer" thread... line #19.


Thx-RNMarsh
 
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#3,183
No. Never saw before.... but then I have only been on this DIYAudio thing for a year or less. And, i dont generally visit diy places....
Is there a newer one and -or a better one that is completed as much -- pcb/bom etc and a -120 or floor?? I would like to see even better here as you and others have in the works.... But when it comes to building and constructing - it gets to be a pretty daunting a task. BTW -- how is your osc/gen coming along?

-Richard M
 
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#3,184
RNMarsh said:
No. Never saw before.... but then I have only been on this DIYAudio thing for a year or less. And, i dont generally visit diy places....
Is there a newer one and -or a better one that is completed as much -- pcb/bom etc and a -120 or floor?? I would like to see even better here as you and others have in the works.... But when it comes to building and constructing - it gets to be a pretty daunting a task. BTW -- how is your osc/gen coming along?

-Richard M
Click to expand...

I'm just taking it to the next level. It seems I'm onto ver3 before ver2 is even built.
 
#3,185
Hi Richard -- like all geeks, I have my own opinions of suitability and usability. I wouldn't have done many things that he did, and yet some of it is really fine. So it's just one of those personal preference things about parts, circuitry, implementation, etc. Overall, a fine effort.

I choose to wait for David's oscillator, then think about analyzer after that; and I think I'm going to go with a Twin-T for the basic notch in the analyzer.
 
#3,188
Its a race between you and Samuel... to the finish. pressure, pressure, pressure. Can't miss the dreaded "dead-line" [pressure] under penalty [pressure] of something worse than death.

Or, will it be the result of a collaboration?

Curious minds want to know. How is the progress coming along? [more pressure]


-Thx-RNMarsh
 
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#3,189
RNMarsh said:
Its a race between you and Samuel... to the finish. pressure, pressure, pressure. Can't miss the dreaded "dead-line" [pressure] under penalty [pressure] of something worse than death.

Or, will it be the result of a collaboration?

Curious minds want to know. How is the progress coming along? [more pressure]


-Thx-RNMarsh
Click to expand...

Well I'm certainly not going to make compromises with the design and then say oh I'll fix that part up later just to get something out there. It's not product.
 
#3,191
Comparison -

These all seem to be based on the ShibaSoku design concepts -- Panasonic et al ---

The VP-7722A uses dual notch filters. Notch depth is at least 140dB.

It measures to .0001% directly from front panel display> -120dB.

The internal oscillator does -130dB. AND, the Panasonics are Accurate down to lowest spec'ed levels.

[I tried to download the files of notch filter block diagram etc but they are too large.
Try some other way, later.... use lower rez probably.]

With the ShibaSoku 725D I could see from the monitor output down to a noise floor of at least -150dB.
As I recall, the notch was at -160dB. I think it was Demian (?) who said it used 3 notch filters.
It would notch/filter out some of the noise near it to see it.

Thx-RNMarsh




-RNM
 
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#3,193
jan.didden said:
Just found out that my Boonton 1130 lacks the two optional plug-in filters.
That means no HP 400Hz filter.
Bummer - I have just a bit over -90dB, most of it mains ripple.
Anyone knows a source of Boonton filters 😱

Jan
Click to expand...

Ask Demian -- he had some PCB's burned for his 1120 for some such purpose.
there are schematics in the Boonton manual for these and other filters.
 
#3,194
Boonton filter board

Attached is a layout for ExpressPCB for a universal filter board and a spreadsheet indication how to assemble it for the different filters.

The ideal opamp for here still need to be found. The filter has higher THD that the rest of the system when close to the cutoff.
 

Attachments

#3,196
I have three around here somewhere. Never had time to get the parts and assemble any. However if someone is so inclined I could help with parts and incentives. I just have a severe shortage of time for non-critical projects.

My last two techs got real jobs/school and I'm looking. . .
 
#3,198
1audio said:
I have three around here somewhere. Never had time to get the parts and assemble any. However if someone is so inclined I could help with parts and incentives. I just have a severe shortage of time for non-critical projects.

My last two techs got real jobs/school and I'm looking. . .
Click to expand...

I'll probably layout a board myself - I find ExpressPCB too expensive compared to my house house, so to say.
When I build my 400Hz filter I'll fix you up one and test it.

Jan
 
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