'80 Marshall 2204 Master Model Mk 2 Lead 50W | Getting Rid of Some Nasty Noise

[@PsionicAudio]

Sorry about the "phones or other tiny speakers" bit. Forgot to delete that from the template from the previous video.

[@GL64]

Oooh one of my favorite Marshalls circuits. More please!

[@goodun2974]

Re Lyle's confusion between V1A and V1B: this is easy to do, partly because if you look in an RCA or other tube manual, what you might be hardwired (see what I did there?! 😁) to think of as the "second" triode consisting of pins 6, 7, and 8 are actually referred to as "triode unit 1" and pins 1,2, and 3 are "triode unit 2". As for which half of the triode is used as the earlier, or "first" gain stage, it could be either one, depending on the OCD of the designer. My OCD says that the earlier gain stage should be marked "V1A" (or V2A etc) on the schematic, as a mnemonic aid to help remember the direction of signal flow and added gain when troubleshooting, but it could well be that the V1A gain stage on the schematic is actually accomplished using triode unit 2 (pins 6, 7 and 8) according to a tube manual. This can become even more confusing if the circuit uses a dissimilar dual triode such as a 12DW7/7247 (seen in Ampegs and Magnatones) where one triode = a 12AX7 and the other triode = a 12AU7.....

[@thomasbailey9605]

Agree! 4.7k is SOOO much nicer than the stock 10k cath resis! Great mod.

[@TheAxe4Ever]

When flushing preamp tube sockets with isopropyl alcohol, make sure to wick it out using only Brawny paper towels because, you know.....TONE man! Brawny has the best tone. But seriously, another awesome video Mr. Psionic!

[@weschilton]

JCMs definitely prefer the Brawny tone of Brawny.... or something. ;)

[@zbaby82]

Coffee filters can clean without leaving any fibers behind.

[@m-baka]

omg this helped me so much with a similar problem 👌🏼👌🏼👌🏼👌🏼👌🏼 Thank you!

[@matthewf1979]

Dropping the cold clipper cathode value just sounds better to me.

[@thomasbailey9605]

PA, do you prefer alcohol to Deoxit D5 for tube cleaning? If so, why?

[@PsionicAudio]

Yes. Because iso evaporates but D5 leaves a conductive film.

[@thomasbailey9605]

@@PsionicAudio yes....that makes sense. Thank you. I really enjoy your vids! Cheers

[@waynegram8907]

I'm guessing that most preamp tubes cathode voltage specs are rated much lower than the plate voltage specs. If you put a preamp tube that's it's cathode voltage rating is lower it will cause noises in the amplifier because the amplifier cathode voltage is higher than the tubes specs of the cathode voltage specs? The tubes data sheets will tell the specs

[@viktor86bt]

Could that DC leaking plate to grid cap have let through all of the plate voltage and into your guitar cable? Thanks

[@PsionicAudio]

Yeeeeessss, but it's extremely unlikely. Still not good practice.

[@viktor86bt]

Yikes!

[@ernestschultz5065]

Have you ever converted a pcb amp to a turret/eyelet or a point-to-point?

[@PsionicAudio]

Several times. Look though the videos on the channel.

[@danielsaturnino5715]

I wonder if there are any brushes small enough to fit the tube socket conectors. And if one can vaccum a tube socket with alcohol and not blow the vaccum cleaner apart from ignited alcohol vapors :)

[@shanedolman1368]

I have tried inter dental brushes, be careful though.

[@srenalwan4829]

Pipe cleaners can do the trick.🤓

[@goodun2974]

A set of paint-sprayer tip-cleaning brushes is about $3 from HF; basically the same as the "tube socket brushes" sold by electronics suppliers for $10 or more. They're soft nylon, okay for cleaning grease and grime after spraying the socket with alcohol, or removing traces of DeOxit that somebody stupidly sprayed into the socket, but they don't do much to remove tarnish or corrosion.

[@danielsaturnino5715]

@@goodun2974 thank you

[@goodun2974]

@@danielsaturnino5715 To really clean tube socket contacts and remove tarnish, I use a wound guitar string of .036 to .039 diameter, worked back-and-forth inside the contacts like a miniature round rasp or file. This works much better then soft nylon brushes. If you can find a way to chuck it into a miniature battery operated Dremel tool or something similar, such as the battery powered rotary engraver sold at HF, you can clean each contact in seconds. Be aware that depending which direction the string is wound, it could tend to unravel itself inside the contact, and so you either have to use a different brand of string that is wound in the opposite direction, or reverse the batteries to reverse the motor direction if that is possible, or seal the very tip of the string with solder or superglue.

[@johnwilliamson467]

Not that complicated cap from grid to plate because signal inverts in a tube it is negative feedback . Small styrene for rf filtering sound better than ceramic and are far more linear .

[@PsionicAudio]

It's complicated if I stop to explain how local negative feedback works. I just try to focus on a few issues at a time in the videos.

[@johnwilliamson467]

@@PsionicAudio I would hope that those who do not understand would look up negative feedback . At some point more knowledge help everyone . You do fine videos .

[@Rocky-sn6fl]

Heisenberg is Alive!

[@russellesimonetta3835]

Uhhh ,, when I see circus boards I get a disapointed feeling. Kind if like buying a hamburger made of soy protein. Cheap imitation. I look forward to your ceriatone deep dive.

[@weschilton]

These are pretty beefy circuit boards... not the cheap flimsy stuff used today.

[@weschilton]

Also hand-wired vintage Marshalls are pushing $20k these days!

[@PsionicAudio]

Sure were a lot of great records made with PCB era Marshalls...

[@kbkman7742]

Depends on the amp man, some people do it very well, some people do it as cheaply as possible without a care for longevity. I would buy a pcb friedman, a uk pcb orange, a pcb marshall like the one in the video etc. Some amps are actually better suited to pcb because of the layout capabilities

[@russellesimonetta3835]

@@kbkman7742 yeah but I should make clear that I'm a tube amp hobbyist! I see a amp with a circuit board and if I want that amp I will attempt a clone! It's about the classic vintage ways of amp building. Not buying.