Tube Amp Archive

R.G. wrote: ↑Tue Nov 24, 2020 10:54 pm Germanium junctions leak just about 1000 times as much as silicon, so you have to take leakage into account.

OK... This is exactly what I need to know! Thanks for taking the time to educate... it is very much appreciated

Don

To switch between two three-leaded devices, you need to switch at least two of the pins. You can leave the third pins tied solid. This is definitely the consideration that I had with my initial questions and comments. If what pompeiisneaks is saying is correct tho (a transistor working as an anode-...

roberto wrote: ↑Tue Nov 24, 2020 6:51 am Instead of switching, I'd treat it like a plexi double input stage.
Give the possibility to blend the signal of the two: you have both, use them!

Now this is something I haven't considered Cool Idea! maybe I should order another OC-44? that's my favorite sound

Don

Rather than try to select between transistors, I would build both (complete) circuits in the same enclosure and just switch the input to either one. Use a 4PDT on/on switch to route the input to and from each. This way, you have each transistor biased correctly and you just switch between the circu...

Treat a transistor in this way like a triode. If you cut signal to the the base that's like cutting signal to the grid. You could just take the signal into a switch that basically outputs to either base. Another means could be to swap the anode(collector) b+ connection between the two so that one i...

Hi, I've been working on tube amps for a while but I have shy'd away from pedals due to a lack of understanding and working knowledge of transistors, chips, op amps etc.... I'm going to build my first non-tube pedal using PNP Transistors (a basic Rangemaster) and I would like to use one OC-44 and on...

Thanks Colossal, Yes depending on the brand of rectifier i get between 312V & 316V. The Sovtek came in a bit lower than JJ, Sylvania, Mazda or GE. Honestly I havent acually checked the ?-0-? on the PT yet but I do know that there's only about 3/4 the iron in the stock PT as there is in Heyboer and M...

Hey All, I have scoured the interwebs and have found very little information regarding The Vietnamese Hand Wired AC30. I took one on trade for some guitar work a while back and my immediate impressions were that it sounded good yet not as rich in content and feel as other AC30 or AC30 type amps that...

I have my own JMJ amplifiers------- I hope you didn't kill any of your EL84's. Wow, That's great... I'd love to hear clips of your amps sometime. I went to your website & I'm intrigued by your JMJ30. That's exactly what I had in mind to build for myself next. The kid that I helped with this amp is ...

it looks like your 62R/68R cathode switch is wired incorrectly------- Make sure your 220k's on the EL84 input grids are grounded well. Thanks Masco! The 1/2 power switch is ok... had to stare at it for awhile to convince myself but it tests correct with the meter. The switch in the 1/2 power mode r...

a 5y3 recto should have gave up with the current draw of this amp if it's burning up cathode resistors no? ----- is your cathode bypass cap going bad, leaky or shorted? Hey Steve, Thanks for the reply! Yes, I thought that the 5y3 should have at least minimized the runaway current. It did reduce the...

While the Voltage is rising you can stop playing and the voltage will stay put for a moment and then begin to slowly drop but not all the way back down to it's original 250Volts. I've attached a Voltage Chart to this post. It may be helpful. [IMG:791:1024]http://i1200.photobucket.com/albums/bb329/d...

You didn't mention the standby switch - did you try bypassing it? .....Also when bypassing the choke, it's a good idea to disconnect both of the choke's wires from the circuit, just in case there is some weird leakage from its winding to the core (and therefore, chassis ground). Thanks Lou, I'll tr...

I would suspect a bad power tube. Thanks xtian! Appreciate the feedback. Yea, I suspected that maybe I had a bad tube but I replaced the el84's with a known good set and nothing changed... I'm beginning to get the feeling that I've done something dumb and that I'm going to be embarrassed when I fin...

Hi, I'm looking for some advise on how to pinpoint a problem with my AC30/4 Build. The Build has an ef86 Channel, A Normal Channel, a Master Volume ala Matchless, a 1/2 Power Switch ala Matchless. It's based on the Layout from Hoffman [IMG:772:434]http://i1200.photobucket.com/albums/bb329/dongallop/...