Search found 805 matches

by rdjones
Tue Jul 22, 2014 1:39 am
Forum: Fender Discussion
Topic: High Power Princeton?
Replies: 11
Views: 1928

Re: High Power Princeton?

I have a client who is inquiring about a higher powered Princeton build. He wants to retain the cathodyne phase inverter. Any ideas??? Thinking about 30-45 watts, used as a clean amp only... Thanks! That would be a sorta Princeton Boogie, although my "Prune Boogie" has an LTP. There's no reason a c...
by rdjones
Tue Jul 22, 2014 1:12 am
Forum: Garage Talk
Topic: SUMMER NAMM 2014
Replies: 9
Views: 867

Re: SUMMER NAMM 2014

Went to the NAMM show on Saturday, the 19th. Not too many amp makers. It was my opportunity to see Andy Fuchs as this is the only time I get to see him after I moved out of Long Island(just before Sandy hit). It was a nice visit and I got to see and hear the bass cabs I co-designed with him. Oh, do...
by rdjones
Thu Jul 17, 2014 4:18 am
Forum: Garage Talk
Topic: Fender AA764 / passive equalizer question
Replies: 13
Views: 1094

Re: Fender AA764 / passive equalizer question

Thank you, Leo_Gnardo and rdjones. I've read up on cathode followers and I see what you're saying. While I'm here, I have two other (unrelated) questions: 1. I notice on the MOD-101 schematic below that they're sharing the resistor and capacitor on the two pre-amp cathodes; what is the effect/advan...
by rdjones
Thu Jul 17, 2014 3:52 am
Forum: Garage Talk
Topic: My old man has passed away.....
Replies: 22
Views: 1242

Condolences

by rdjones
Wed Jul 16, 2014 3:00 am
Forum: Technical Discussion
Topic: 65 Deluxe reverb reissue Power transformer problem
Replies: 11
Views: 1016

Re: 65 Deluxe reverb reissue Power transformer problem

What's the failure mode ?
Open primary ? HT secondary ?
Ohm out the windings, and identify a pattern.

Please make sure the caps are discharged !

rd
by rdjones
Wed Jul 16, 2014 2:46 am
Forum: Garage Talk
Topic: Fender AA764 / passive equalizer question
Replies: 13
Views: 1094

Re: Fender AA764 / passive equalizer question

That's an awfully heavy load to drive from the plate of a 12AX7. There's no DC blocking for R5. I'd say no, not as a straight transplant it wouldn't work. At the very least you'd need a cathode follower to drive the stack and appropriate DC blocking. Then there's the question of insertion loss ... rd
by rdjones
Tue Jul 15, 2014 5:05 am
Forum: Technical Discussion
Topic: Reducing Grid stopper plus raising capacitance
Replies: 14
Views: 1097

Re: Reducing Grid stopper plus raising capacitance

Let's leave capacitors out of the story. It's not that simple. The capacitance (stray capacitance + the tube's internal interelectrode capacitance + any intentionally added cap) and the series resistance interact directly with the tube's transconductance, which is quite high in a 12ax7. This determ...
by rdjones
Tue Jul 15, 2014 4:41 am
Forum: Technical Discussion
Topic: Reducing Grid stopper plus raising capacitance
Replies: 14
Views: 1097

Re: Reducing Grid stopper plus raising capacitance

Isn't a small cap from grid to plate a kind of feedback circuit? Usually used for stability? I would get back to the original schematic and go from there. In a sense, yes. I call it the "Miller Mod" because it mimics a larger Miller capacitance. The Miller effect amplifies the grid-to-plate capacit...
by rdjones
Thu Jul 10, 2014 11:55 pm
Forum: Technical Discussion
Topic: Can you guys look at this.....
Replies: 20
Views: 1728

Re: Can you guys look at this.....

I've felt a mild zap from an amp that had been unplugged for 2 days. Just like a gun should be treated as if "always loaded" a tube amp is "always hot" until known and measured as discharged. ;-> Sometimes I'll stick a bleeder on the far end of the PS string near the preamps. This has the added prot...
by rdjones
Thu Jul 10, 2014 4:42 am
Forum: Technical Discussion
Topic: Can you guys look at this.....
Replies: 20
Views: 1728

Re: Can you guys look at this.....

Geez...even Wiki knew what it was for. Does not talk about calculations, but it is a good explanation of function. Thank You IIRC the US codes call for 50 volts or less within 5 minutes. Other areas are more strict, AUS are EU are 50 volts or less within 1 minute. Calculation for a tube circuit is ...
by rdjones
Thu Jul 03, 2014 4:06 am
Forum: Garage Talk
Topic: Solid state amps -- "don't underpower the speakers"
Replies: 5
Views: 603

Re: Solid state amps -- "don't underpower the speakers"

The underlying truth is "Don't clip the signal".

Quite obviously the 600 watt amp is going to be more dangerous to the 600 watt speaker than the 300 watt amp if both are driven equally into clipping.

rd
by rdjones
Fri Jun 13, 2014 11:52 pm
Forum: Garage Talk
Topic: How to make a quick link on a post.
Replies: 22
Views: 1325

Re: How to make a quick link on a post.

Greetings to ALL. I hope I'm in the right place for this question. If it isn't, I apologize, and hope for a correction. My question is this : How does one make a quick link in a post. Example : A schematic for my amp, when I am posting about it. I am sorry to ask such a simple question, and I don't...
by rdjones
Thu May 29, 2014 6:49 am
Forum: Garage Talk
Topic: The eagles on tour
Replies: 59
Views: 3819

Re: The eagles on tour

Structo wrote:Did he still have his hair? :lol:
[img:600:600]https://lh3.googleusercontent.com/-FIOB ... ampton.jpg[/img]
Ricky Skaggs w/ Frampton and Paisley, this past Nov.
Peter played through a Matchless.

rd
by rdjones
Tue May 27, 2014 6:48 pm
Forum: Fender Discussion
Topic: Fender Super 60 Red Knob Diagnosis (Blowing Fuses)
Replies: 17
Views: 2159

Re: Fender Super 60 Red Knob Diagnosis (Blowing Fuses)

Firestorm wrote:D101 and D102 are flyback diodes on the ends of the OT. If you use 1N4007, you should put three in series.
Correct, according to the parts list D101-102 are 3KV rated.
The idea is to damp any flyback on the OT primary without shorting.

reddog
by rdjones
Sun May 25, 2014 5:10 am
Forum: Trainwreck Discussion
Topic: Monkeymatic S'express 15-watt
Replies: 54
Views: 5958

Re: Monkeymatic S'express 15-watt

xtian wrote:Faceplate design.
Danger = 11 ?

8)

reddog