Search found 4679 matches

by mediatechnology
Tue Jan 12, 2021 12:39 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 100
Views: 55306

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

My reasoning behind selecting the 15K resistors to <1% was to reduce the overall error of that arm and therefor reduce the value of the trim. With larger-value 15T trims the mechanical backlash in the adjustment is apparent as one attempts to adjust to a really deep null. The depth of the null howev...
by mediatechnology
Tue Jan 12, 2021 10:29 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 100
Views: 55306

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Twin T calculator: http://sim.okawa-denshi.jp/en/TwinTCRkeisan.htm I use that site all the time but forgot to look there for a twin-T. The twin-T notch filter I published earlier in this thread will likely be what I layout on the PCB. It's from Jansek. The component sensitivity hasn't been much of ...
by mediatechnology
Mon Jan 11, 2021 12:44 pm
Forum: Test, Measurement and Repair
Topic: The iDefender USB Ground Isolator
Replies: 2
Views: 145

Re: The iDefender USB Ground Isolator

I bought a second USB A to A from B&H Video and we'll see how that works out. I'll repost iDefender's response to my open ticket on the C to C version. The promptly-delivered USB C to C iDefender from B & H Video works flawlessly. Now, both 2i2s have isolators. My desktop PC's 2i2 is dead quiet. I'...
by mediatechnology
Mon Jan 11, 2021 11:01 am
Forum: Document
Topic: Zener Diode Table
Replies: 3
Views: 68

Re: Zener Diode Table

My brother's former electronic distributorship, KA Electronic Sales, had a desk pad with tables like this as a promo/swag item.
I named my website to honor my brother who passed away in 2002.
I saved a sheet from that pad and should scan it for historical perspective.
by mediatechnology
Mon Jan 11, 2021 8:23 am
Forum: The Peabody Lounge
Topic: Radio World Commentary: “The Old Goats Are Going Away”
Replies: 0
Views: 38

Radio World Commentary: “The Old Goats Are Going Away”

Radio World Commentary: “The Old Goats Are Going Away” My first real bit of engineering was converting a 50 kW FM station to stereo in 1963. No one listened to FM then, I think there were 10 FM radios in the city and five were in Cadillacs owned by mob hit men. When we talk of RF, we talk of a whol...
by mediatechnology
Mon Jan 11, 2021 6:25 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 100
Views: 55306

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

The filter almost has to be passive in order be near-distortionless and it also needs to be made with ultra-low distortion passive components.

When I make a second Nacho filter, for either the right channel or for a quasi-balanced filter, I'll have a filter to check the filter.
by mediatechnology
Sun Jan 10, 2021 8:55 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 100
Views: 55306

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

With the ULDO at the input of the DUT, the Focusrite at the output, you get the FFT then calculate the THD+N. This should give an extremely accurate measurement at 1KHz. Only to a point. The Focusrite's A/D has a residual THD of around 0.0002% (https://proaudiodesignforum.com/forum/php/viewtopic.ph...
by mediatechnology
Sun Jan 10, 2021 3:57 pm
Forum: Document
Topic: Zener Diode Table
Replies: 3
Views: 68

Zener Diode Table

From the Logwell site comes this table of popular Zener diodes.

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by mediatechnology
Sun Jan 10, 2021 3:51 pm
Forum: Document
Topic: Incandescent Lamp Substitutions For Longer Life
Replies: 0
Views: 21

Incandescent Lamp Substitutions For Longer Life

For those that service vintage gear and like the look of incandescent lighting here is a table from the Logwell site providing substitutions for longer life.

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by mediatechnology
Sat Jan 09, 2021 2:56 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 100
Views: 55306

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Thank you JR. Its actually a Wien topology: The outputs of the two stages are out-of-polarity and provide a balanced output. IC3B is an inverter but the compensation caps make it look like a state variable topology. Anti-polarity outputs open the door to simple FW rectification but I found I didn't ...