Search found 18 matches

by Bill Wilson
Tue Dec 10, 2019 6:12 pm
Forum: Pro Audio Design
Topic: MEP-250 Bridged-T equalizer
Replies: 14
Views: 7267

Re: MEP-250 Bridged-T equalizer

In the Sontec circuit C25's value is 33mfd, 6vdc. The values for all 5 filter frequencies are listed ln the lower right hand corner of the schematic.
by Bill Wilson
Wed Nov 27, 2019 5:08 pm
Forum: Pro Audio Design
Topic: Benchmark Mic Preamp from 1984 - Active Preamp History
Replies: 39
Views: 67410

Re: Benchmark Mic Preamp from 1984 - Active Preamp History

Sorry Wayne: I had forgotten I was on the wrong forum. It can be found on <Groupdiy.com> Look at the technical forum for Neotek, it is either the last or next to last post. By carefully matching the resistors around the discrete transistors on the front end; the CMRR approaches 100 db. I used 5% car...
by Bill Wilson
Sun Nov 24, 2019 10:41 pm
Forum: Pro Audio Design
Topic: Benchmark Mic Preamp from 1984 - Active Preamp History
Replies: 39
Views: 67410

Re: Benchmark Mic Preamp from 1984 - Active Preamp History

Paul Buff brought out his Transamp around 1975. In 1977 I was service mgr. for the Nashville MCI dealer. I met with Paul at Quadraphonic Studio; where we installed a Transamp in place of one summing amplifier, as a test toward improving the noise figure in the MCI 500 series console. It did provide ...
by Bill Wilson
Tue Mar 05, 2019 7:16 am
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 294701

Re: Flat Phono Preamp Based on John's P10 and 2SK389

No Wayne: The 103R cartridge sees a resistive load of 1.6k. As moving coil cartridges are almost universally flat in their response it makes little sense to try & load it with a low resistance. The 1.6k is made up of 2ea, 802 ohm 1/4w metal foils that also provide the necessary ground reference need...
by Bill Wilson
Mon Feb 11, 2019 3:49 pm
Forum: Test, Measurement and Repair
Topic: Heathkit IM-5238 AC Voltmeter Repair
Replies: 2
Views: 2824

Re: Heathkit IM-5238 AC Voltmeter Repair

I have a pair of these I built in 1978; when I went into studio equipment repair in Nashville. i have never had a problem with them other than a sticking meter movement. The meters were made by Dixon & I was able to find a replacement at Sky Craft in Orlando. Simply swapped scales & 8nstalled it. I ...
by Bill Wilson
Wed Jun 20, 2018 5:21 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 294701

Re: Flat Phono Preamp Based on John's P10 and 2SK389

Yes Wayne it is the Preamp that Joe Neil did the pcb layout. The 103R is not retipped it is a slightly better cartridge. Some of the users that use mike xfmrs. for stepup claim it is as good as any in the up to $1000- range. I had talked to an applications engr. at That & designed a low Z resistive ...
by Bill Wilson
Mon Jun 18, 2018 10:23 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 294701

Re: Flat Phono Preamp Based on John's P10 and 2SK389

Hi Wayne: Thought I would jump in with my two cents. I designed my own moving coil phono preamp, using either That 1510 or AD SSM2019 mike pres. for the balanced input. I based the design around Denons 103R M/C cartridge. The preamp gain is set for 1000 times; as the output from the 103R is 280 micr...
by Bill Wilson
Thu May 31, 2018 1:20 pm
Forum: Pro Audio Design
Topic: A new way to produce lettered front panels
Replies: 3
Views: 2657

Re: A new way to produce lettered front panels

For my initial front panel overlay, I used MS Word to print the lettering; also had to figure the placement of the controls. Then used a program named "Zamzar" to convert the file to one accepted by the sign shop. Now I am doing each control separately using 1. print, 2. cut & paste. Next take to th...
by Bill Wilson
Wed May 30, 2018 4:12 pm
Forum: Pro Audio Design
Topic: A new way to produce lettered front panels
Replies: 3
Views: 2657

A new way to produce lettered front panels

My local sign shop in the Tampa Bay area, introduced me to a company by the name of "Rowmark". They produce plastic sign material in both 1/32" & 1/16" thickness. The material comes in many different colors & is laser engraveable. Wayne asked me to share this method after seeing the results. You can...
by Bill Wilson
Thu May 24, 2018 5:36 pm
Forum: The Peabody Lounge
Topic: RIP Joe Neil
Replies: 13
Views: 6966

Re: RIP Joe Neil

I am stunned! I first met Joe in Feb. 1978. He was chief engineer at Bob Richardsons studio, just off I75 in Atlanta. I was service mgr. for the MCI Nashville dealer & was there to tune the eq on the control room monitors. We hit it off right from the start. We rekindled our friendship 2 yrs. ago. J...