Search found 3979 matches

by mediatechnology
Wed Nov 20, 2019 5:24 am
Forum: Build
Topic: Flat Balanced Input Moving Coil Phono Preamp Construction Information
Replies: 14
Views: 1704

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Found these plots that I did before it was a PC board: Bill - I'm hoping to keep it the same board size as the MM preamp which is 3x4". Here are some noise measurements with the Protoboard moved off the workbench about a foot and the hum component from a nearby 100W linear supply's hum "vortex" null...
by mediatechnology
Wed Nov 20, 2019 5:15 am
Forum: Build
Topic: Flat Balanced Input Moving Coil Phono Preamp Construction Information
Replies: 14
Views: 1704

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

There are some 30Ω curves in the original thread. This is what it looks like with a 30Ω termination of a real DL-103||100Ω. I thought I would grab some quick shots of the low-level hum performance of the preamp and the "normal," differential mode, hum pickup of the DL-103. The preamp wiring is STP/b...
by mediatechnology
Tue Nov 19, 2019 10:42 am
Forum: The Peabody Lounge
Topic: South Dakota Spends Nearly $500,000 On Anti-Meth Ad Campaign With Tagline "Meth. We're On It"
Replies: 0
Views: 11

South Dakota Spends Nearly $500,000 On Anti-Meth Ad Campaign With Tagline "Meth. We're On It"

South Dakota Spends Nearly $500,000 On Anti-Meth Ad Campaign With Tagline "Meth. We're On It" A video shows Governor Kristi Noem telling the camera, “I’m on meth,” before she explains that “on it” means “on the case of meth.” TV ads, posters, billboards and a website will feature the motto at a cos...
by mediatechnology
Mon Nov 18, 2019 10:02 am
Forum: The Peabody Lounge
Topic: They Walk Among Us
Replies: 22
Views: 1066

Re: They Walk Among Us

Meanwhile back across the pond we have this inquiry: "House Minority Leader Demands ABC Explain Why They Shelved Epstein Story" House Minority Leader Kevin McCarthy (R-CA) fired off a letter to ABC News President James Goldston demanding to know why the network shelved a story on Jeffrey Epstein aft...
by mediatechnology
Sun Nov 17, 2019 7:25 pm
Forum: The Peabody Lounge
Topic: They Walk Among Us
Replies: 22
Views: 1066

Re: They Walk Among Us

Prince Andrew's Epstein-Related BBC Interview Was "Catastrophic Mistake" Last night, televisions showed the perfectly state-managed scene of Prince Andrew, the Duke of York, sitting down BBC Newsnight’s Emily Maitlis conducting an interview recorded at Buckingham Palace this past Thursday. In it, a...
by mediatechnology
Sun Nov 17, 2019 4:10 pm
Forum: Build
Topic: Flat Balanced Input Moving Coil Phono Preamp Construction Information
Replies: 14
Views: 1704

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

I just finished building a ZTX851 moving coil preamp board and thought I would post the noise spectra. https://proaudiodesignforum.com/images/jpg/MC_Preamp ZTX851_Noise_111719.jpg I haven't measured the actual gain - it usually runs just under 62 dB so we'll call it 61.5 dB. The PCM4222EVM A/D load...
by mediatechnology
Sun Nov 17, 2019 2:03 pm
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

The trick is to punch through the emitter to reach the base at many places over the large transistor. That's what I'm seeing in the drawing - lot's of distributed base contacts. My rbb of 5.5Ω may be low, my last guestimate was 8Ω. I've asked Hans at diyaudio to run his sim for the MC preamp adjust...
by mediatechnology
Sun Nov 17, 2019 11:19 am
Forum: The Peabody Lounge
Topic: They Walk Among Us
Replies: 22
Views: 1066

Re: They Walk Among Us

Do not assume bad intent when the reason my just be bad judgement, or just different judgement.
I have to assume bad intent whenever anyone tells me that they want me dead.
They've clearly said that.
by mediatechnology
Sun Nov 17, 2019 9:29 am
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

What in this geometry makes the transistor very low noise ? The Zetex explanation is too sketchy for me.
I don't know but I'll take the results.
by mediatechnology
Sun Nov 17, 2019 7:08 am
Forum: Pro Audio Design
Topic: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance
Replies: 8
Views: 128

Re: Low Noise Transistors: ZTX851 versus ZTX689B Noise Performance

The LM394 did use multiple transistors. About all I can find on Zetex technology is the "Matrix Geometry" used to provide low distributed base resistance to what appears to be a single transistor. Rather than many transistors we have many base contacts. https://proaudiodesignforum.com/images/jpg/Zet...