Search found 13258 matches

by martin manning
Mon Feb 16, 2009 1:25 pm
Forum: Dumble Discussion
Topic: Etching a board set for my HRM build...
Replies: 49
Views: 5213

Re: Etching a board set for my HRM build...

The boards look really good! I've decided to give the Pulsar system a try. I should have it within a week, and I'll report back with findings. The special materials aren't very expensive, especially if the results are reliable. BTW there is a note on the Pulsar site that says the laminator doesn't w...
by martin manning
Fri Feb 13, 2009 10:00 pm
Forum: Technical Discussion
Topic: Calculating the value for a safety resistor
Replies: 6
Views: 1700

Re: Calculating the value for a safety resistor

I haven't looked it up in TUT, but it looks right. The failure is the same as when a pot becomes "noisy," so it certainly could happen. On the other hand, there are milions of amps out there that are not wired "fail-safe." Maybe one of the pros can comment on how often it happens. There are other wa...
by martin manning
Fri Feb 13, 2009 6:04 am
Forum: Technical Discussion
Topic: Calculating the value for a safety resistor
Replies: 6
Views: 1700

Re: Calculating the value for a safety resistor

The failure that the safety resistor is protecting against is the pot's wiper losing electrical contact with its element. If that happens, the grid voltage is on average zero, and there will be excessive current flow through the power tubes and the OT. In normal operation, the bias voltage is set by...
by martin manning
Sat Feb 07, 2009 1:21 pm
Forum: Dumble Discussion
Topic: Lindley's SSS used to be an ODS?
Replies: 14
Views: 1846

Re: Lindley's SSS used to be an ODS?

According to a recent interview and photo in The Fretboard Journal , that amp is ODS #002, a 50W. Controls are Vol, then the three slide switches: Bright, Deep, Guitar/Mic, T, M, B, Overdrive, Level, and the slide switch on the right is labeled "Accent." Anybody know what the accent switch does? And...
by martin manning
Fri Feb 06, 2009 4:08 pm
Forum: Technical Discussion
Topic: Div by 13 amp hum
Replies: 16
Views: 7288

Re: Div by 13 amp hum

I have a 17/39 and it works fine. Also try to figure out if the hum is 60Hz or 120Hz. Two different sets of problems; two different sets of solutions. How does one determine whether it's 60Hz or 120hz? Thanks, CW Use a 'scope. If you don't have access to one of those, the A-string 2nd fret (B2) on ...
by martin manning
Fri Feb 06, 2009 1:51 pm
Forum: Dumble Discussion
Topic: Etching a board set for my HRM build...
Replies: 49
Views: 5213

Re: Etching a board set for my HRM build...

ic, what "system" are you using to do this? All-DIY? I have looked at this kit: http://www.pulsarprofx.com/ Maybe the paper sold there and the overcoating step would eliminate the fuzzy edges and touch-up you are having to do. The laminator suggested looks like a good bet for consistent results too,...
by martin manning
Wed Feb 04, 2009 1:32 pm
Forum: Dumble Discussion
Topic: Dumble Overdrive Special 80's Chassis Dimensions?
Replies: 3
Views: 1661

Re: Dumble Overdrive Special 80's Chassis Dimensions?

Those look like the dimensions of the Natchanis chassis. I used #124 photos and known part dimensions to get mine. Anybody get measurements from a physical unit? I'd be glad to update the drawing.

MPM
by martin manning
Wed Feb 04, 2009 1:26 pm
Forum: Dumble Discussion
Topic: Dumble ODS Video on YouTube
Replies: 65
Views: 10010

Re: Dumble ODS Video on YouTube

Mystery solved Re the #124 photos, then? It has NC on one side of the PAB slide switch.

MPM
by martin manning
Wed Feb 04, 2009 12:09 pm
Forum: Technical Discussion
Topic: Gibson GA-77RVT 1963/64 specific schematic
Replies: 5
Views: 1379

Re: Gibson GA-77RVT 1963/64 specific schematic

You could post this request over at the Music Electronics Forum.

Check this thread there:

http://music-electronics-forum.com/show ... ine&page=2

"Capnjuan" is still on-line, and maybe he has what you're looking for.

MPM
by martin manning
Fri Jan 30, 2009 7:06 pm
Forum: Technical Discussion
Topic: Load Line, Q-Point, and Frequency Response in Excel
Replies: 44
Views: 14460

Re: Load Line, Q-Point, and Frequency Response in Excel

Are you running in Excel or some other program (Open Office, e.g.)? If in Excel, did you check the security level? Tools -> Macro -> Security..., then set to Medium or lower. The latest Mac Office does not support VB macros, so if that is the problem you are out of luck using the buttons. You can al...
by martin manning
Thu Jan 29, 2009 1:10 am
Forum: Technical Discussion
Topic: Load Line, Q-Point, and Frequency Response in Excel
Replies: 44
Views: 14460

Re: Load Line, Q-Point, and Frequency Response in Excel

No problem; this is all good stuff. Yes, this is the so called "five equal voltage ordinates" method (RDH4 p. 564), and it estimates distortion at clipping (signal peak at Vg-k=0). Similar methods using more points are shown to get % distortion at higher orders. There is no reason any of these could...
by martin manning
Wed Jan 21, 2009 4:57 am
Forum: Dumble Files
Topic: ODS #124 Chassis Layout
Replies: 19
Views: 9841

Re: ODS #124 Chassis Layout

Don, you are much more adventurous than I. My plan is to do an ODS with a few minor layout changes and a modernized back panel. This really needs to go into a CAD program so it can be modified as needed and handed to a fab shop when the time comes. I'll likely get to that in the next few weeks. mlp-...
by martin manning
Tue Jan 20, 2009 10:23 pm
Forum: Dumble Files
Topic: ODS #124 Chassis Layout
Replies: 19
Views: 9841

Re: ODS #124 Chassis Layout

Well, I drew this in Powerpoint so I don't think that will be of much additional help to you. I'm looking at getting some quotes from local fabricators once I get everything dialed in for the compopnents and mounting hardware I'm using. I'll have to put it into a real CAD program for that, but it mi...
by martin manning
Mon Jan 19, 2009 2:55 pm
Forum: Technical Discussion
Topic: Load Line, Q-Point, and Frequency Response in Excel
Replies: 44
Views: 14460

Re: Load Line, Q-Point, and Frequency Response in Excel

I made a little update on this. A forum member suggested that it might be nice to have some extra slots and buttons for additional tube types available, so this version has that feature. No bugs reported so far in the original version. Cheers, MPM Edit: attachment removed. See latest version posted ...
by martin manning
Sat Jan 17, 2009 3:51 pm
Forum: Dumble Discussion
Topic: Low pf shielded cable
Replies: 54
Views: 6820

Re: Low pf shielded cable

all of the coax i have, can be attracted by a magnet, rg59, 162, and i can't say that about any of the audio cables i have. I can't offer an explanation why, but i have had issues with use of it in amps. The explanation is simply that there is some ferrous material in it. That is definitely not the...