ShibaSoku Automatic Distortion Analyzer

Jump to Latest
#482
RNMarsh said:
Tweeking the distortion on the AG16B; At 1KHz and 80KHz analyzer filter;

2h and 3H and THD;


View attachment 522245

View attachment 522246

View attachment 522247



OK but could be better.... 😎🙂


THx-RNMarsh
Click to expand...

How did you tweak it? Putting a pot on JFET VR to trim D-G feedback factor?
I think AG16B do not have 2HD trim as a stock , as AG16A do not.

An japanese DIYer said VP7214A(rip off of 7722A's oscillator) is comparable to bit less performance than AG15 in mid frequency but more worse in LF, below 20Hz 7214A distortion start to increase.
I introduced him this thread but unfortunately he is not good at English, he said.


I made to control AG16A from Excel VBA and collect data from 725C.🙂 Uncertain distortion issue is also solved.🙂🙂
 
Last edited:
#484
Shinja said:
How did you tweak it? Putting a pot on JFET VR to trim D-G feedback factor?
I think AG16B do not have 2HD trim as a stock , as AG16A do not.

An japanese DIYer said VP7214A(rip off of 7722A's oscillator) is comparable to bit less performance than AG15 in mid frequency but more worse in LF, below 20Hz 7214A distortion start to increase.
I introduced him this thread but unfortunately he is not good at English, he said.


I made to control AG16A from Excel VBA and collect data from 725C.🙂 Uncertain distortion issue is also solved.🙂🙂
Click to expand...

I used a probe into a VP-7722 and adjusted all trim pots to get lowest distortion at each osc/amp output stage (3 in middle).

I do not have schematic, though and could do more if I had one.



THx-RNMarsh
 
Last edited:
#486
Thank you, RNM.
I tried it yesterday, but it do not help mine.There may be something changed from my AG16A to successor.

I traced the circuit and it (simplified) worked on LTspice but the distortion is awful. There may be some errors.
I think it should not be publically shared why it is shibasoku's property, If someone need it please send a PM me.
 
#488
The distortion in the vp7722a is as low or lower than the AG16b....
Since the osc is included with the analyzer... it is a very good equipment package.

I am going to try to find the control jFET and add a trim pot from G-D to see what that does. A schematic would help a lot.



THx-RNMarsh
 
#493
I just reworked the scans of the xeroxed pages of schematics of the 725B manual. I put the pieces back together so they make some sense and can be followed. I assembled the schematics with the text and uploaded the complete manual to K04BB's manual repository: Manuals - KO4BB You will find it in the misc. test equipment folder soon. I think its together. the source document is not particularly clean or complete. If something is missing let me know and I'll see if its there.
 
#500
1audio said:
As I suggested earlier a handful, no more than 5 or 6, fixed frequencies for testing distortion will show all that really is there to learn on electronic systems.
Click to expand...

I know this is an old post but just curious, which frequencies do you use? I have 1 KHz, 10 KHz, and 11 KHz Victor boards. Right now he is whipping up 260Hz, 19 KHz, and 20 KHz boards for me.

I just picked up one of the VP-7722A's from South Korea on eBay so I've been re-reading this thread a zillion times. 🙂
 
You must log in or register to reply here.
Top Bottom