Search found 11 matches

by fredbloggstwo
Sat Jul 31, 2021 10:15 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Nice one Wayne,

your attenuator board looks a lot better than mine :)

I'll add the osc mods to my board when I am next down the workshop. I also added a switch to the notch filter input to put the osc in circuit. Twisted pair seem to work ok.

Cheers

Mike
by fredbloggstwo
Sun Jul 25, 2021 11:28 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi again Wayne, I tried the OPA 1656 chip in the notch filter and it works fine. Here's some photos of the attenuator I built based on 'O' or 'Box' pads. I recommend this type of pad as it is 'ground free' and so does not have any grounding funnies. My fancy 'scope which also does Bode plots, shows ...
by fredbloggstwo
Sat Jul 17, 2021 3:54 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi again Wayne, I built the 1-2-2-5/10-20-20-50 ratio attenuator according to the spreadsheet I posted and it works well with the stated attenuation spot on. The Schadow switches work well. I also added a 600R termination switch so as to terminate the attenuator chain - the stage after the attenuato...
by fredbloggstwo
Tue Jun 29, 2021 8:44 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi Wayne, Thanks for the kind words. I use a silent switcher to power an existing sound card output interface, but when I bought it it came from the US (instead of Europe where Jan Didden is based) and cost me a fortune in import duties and 'commission. So I have started using a Chinese copy ( https...
by fredbloggstwo
Mon Jun 28, 2021 8:57 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi again,
I forgot to add that to avoid any mains-powered PSU etc. I use a 5 V to +/-15 bucking regulator with a USB input connector. This means the whole thing is fully floating and can be powered from one of those battery packs used to charge up mobile (cell) phones.

Mike
by fredbloggstwo
Mon Jun 28, 2021 8:52 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi Wayne, as promised, here are a couple of photos for your scrap book. is is a case of function over form as I use screened steel boxes for my test kit as you can see, that keeps all the local RF crud out. I haven't done any detailed measurements yet. You mentioned building an attenuator: you may a...
by fredbloggstwo
Tue Jun 22, 2021 3:36 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi Wayne thanks for posting the calculator. I'll give it a try in a day or so. I have got mine working after a little finger trouble on my part :-) and also found what I think are a couple of minor errors in the build guide/testing section. The building was straight forward and I followed your build...
by fredbloggstwo
Mon May 17, 2021 8:43 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

mediatechnology wrote:
Thu May 13, 2021 3:44 pm
Thanks George and Mike!
To answer your question George I have a couple of extra boards.
So where do I sign up - can't see them in your store? :)

Do you have a BOM as well?

Thanks

Mike
by fredbloggstwo
Thu May 13, 2021 12:14 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi Wayne,

Looks a very neat layout

When do you go into mass production :D

Regards

Mike
by fredbloggstwo
Mon Feb 08, 2021 3:19 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 156
Views: 180081

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Hi folks, Just been through this thread and it looks quite exciting. I have a couple of questions though: 1 what would be involved in turning the oscillator into a switched full range device (20 to 20k) 2 if you are trying to get the most from a 5532/5534, have you seen the trick about using an exte...