Search found 1442 matches

by John_P_WI
Wed Feb 28, 2024 5:21 pm
Forum: Technical Discussion
Topic: ....and Now for Something Completely Different!
Replies: 55
Views: 10585

Re: ....and Now for Something Completely Different!

Sadly, David is no longer with us.
by John_P_WI
Mon Sep 18, 2023 6:25 pm
Forum: Garage Talk
Topic: Thinking about moving south
Replies: 152
Views: 69278

Re: Thinking about moving south

Yup, Wisconsin is hell, 9 months of winter with mosquitos the size of birds during the summer. At least we have beer, lots of beer... and more beer.

I hear ya tho, time to move to where the winters are not so severe.

John
by John_P_WI
Tue May 09, 2023 2:05 pm
Forum: Technical Discussion
Topic: High pulse power resistors
Replies: 12
Views: 1099

Re: High pulse power resistors

Hey Phil, I came out of the same industry and used 10k 1 watt carbon comps which became unobtanium, and which the supplier admitted only 3 factories in China were making them - and they were shite. The analog guys ended up using metal oxide in their place, specifically designed for the defib impulse...
by John_P_WI
Wed Feb 15, 2023 2:38 pm
Forum: Technical Discussion
Topic: McIntyre Bluesbreaker
Replies: 6
Views: 737

Re: McIntyre Bluesbreaker

I built it early 90's, Jon was a great guy to talk to back then - before the internet. Parallel input was nice, bright amp, very loud - think of a trainwreck it was meant to be played loud for breakup. If I was to build it today, I think I would probably darken the 100k plate normal side and increas...
by John_P_WI
Mon Oct 10, 2022 6:55 pm
Forum: Technical Discussion
Topic: What do R and C stand for in schematics?
Replies: 18
Views: 1490

Re: What do R and C stand for in schematics?

I can not express this enough, buy a breadboard, a handful of Rs and Cs, a few jfets, 9v battery, a cheap oscilloscope and signal generator. You'll learn more for a few hundred dollar investment than you will asking questions. What's your time worth? Put in the effort to visualize it instead of wait...
by John_P_WI
Mon Oct 10, 2022 5:33 pm
Forum: Technical Discussion
Topic: What do R and C stand for in schematics?
Replies: 18
Views: 1490

Re: What do R and C stand for in schematics?

Why do you need an amp calculator? By simple inspection approximate gain is 20x, 10x and 66x (won't happen), you figure the attenuation and shelving frequencies... But what for? Me thinks this preamp is one of the worst sounding ever, absolutely no soul. I'll take "Let's help write a uni paper for $...
by John_P_WI
Fri Oct 07, 2022 4:01 pm
Forum: Technical Discussion
Topic: Noise after mod
Replies: 7
Views: 763

Re: Noise after mod

Either your "new" bypass cap isn't ground referenced when out of circuit, or you are mixing grounds up and causing a loop.
by John_P_WI
Fri Oct 07, 2022 1:34 pm
Forum: Technical Discussion
Topic: What makes high gain amps to have higher voltage gain thus higher peak dB gain?
Replies: 32
Views: 2270

Re: What makes high gain amps to have higher voltage gain thus higher peak dB gain?

The irony of all of this is that "high gain or distortion amps" in regard to the pre amps have less actual gain than a clean amp. Compare a diode clipped "Jose" mod clamped down to 12v to a SVT. Never thought of the SVT as high gain, but looking at the dB thru the amp it is greater than the "high ga...
by John_P_WI
Thu Oct 06, 2022 6:52 pm
Forum: Technical Discussion
Topic: What makes high gain amps to have higher voltage gain thus higher peak dB gain?
Replies: 32
Views: 2270

Re: What makes high gain amps to have higher voltage gain thus higher peak dB gain?

Without knowing the past context, or care to, remember that dB is a ratio. That being said, what is the starting input voltage of the dB figures that you are asking about? There is a huge difference, for example, using a 0.01 v input instead of 1 v which is already a 40 dB discrepancy in the reporte...
by John_P_WI
Fri Aug 19, 2022 2:43 pm
Forum: Marshall Discussion
Topic: Headfirst videos
Replies: 4
Views: 2446

Re: Headfirst videos

Mark, as a guy born in the 60's and a 20 something in the long hair metal days of the 80's, I approve of his amp tones. Only watched a couple of vids, wish there was something like that when I first started amp work in the early 90s and used to call guys like Jon McIntyre for help. He is honest with...
by John_P_WI
Fri Jul 29, 2022 8:18 pm
Forum: Technical Discussion
Topic: Shipping costs going up?
Replies: 25
Views: 2170

Re: Shipping costs going up?

The worst part is that all of the added "fuel surcharges" never go away, they just become the "norm"...
by John_P_WI
Thu Jun 16, 2022 1:31 am
Forum: Technical Discussion
Topic: Spectrum Analysis Recommendations
Replies: 9
Views: 780

Re: Spectrum Analysis Recommendations

In my past engineering life, a RF engineering God and fellow tube amp builder swore by the Analog Discovery for his home use. Additionally, there is supplemental analysis software such as this: https://youtu.be/7yXUbU5bSGw which will do exactly what you are asking.

John
by John_P_WI
Wed May 25, 2022 10:01 pm
Forum: Technical Discussion
Topic: Low Pass Filter: Math vs Practice
Replies: 16
Views: 1797

Re: Low Pass Filter: Math vs Practice

I'll be a little more cynical and say that the 470k r is simply a carry over from the isolation resistors used in this position of a 2 channel amp, think old bassman or plexi. In reality, it adds some input impedance isolation to the following gain stage as the preceding volume pots are varied makin...
by John_P_WI
Wed Mar 23, 2022 8:36 pm
Forum: Garage Talk
Topic: 13 years?
Replies: 46
Views: 48553

Re: 13 years?

Miles, been a long time, I remember those days. Been here almost 15 yrs, although I don't build or post anymore. Sometimes life "just gets in the way"... Always enjoyed your Marshall clips, recording stories, Scarface, insight and build note banter with Jana... To me that was the great period of TAG...
by John_P_WI
Sun Feb 10, 2019 12:05 am
Forum: Garage Talk
Topic: Stuff I'd like to have
Replies: 32
Views: 2783

Re: Stuff I'd like to have

Man, I'd like to have the building knowledge that I've seem to have lost in my 5 year Hiatus... and it wasn't even good time off! Good to see familiar names still here!