Tube Amp Archive

So I double check the filament wiring. Disconnected it from the 6.3v bulb and used continuity to confirm that they were correct. They are. Then I replaced the two section cap can that contained nodes 1 and 2 and replaced it with another I had in the parts bin. Unfortunately, same results. Still have...

I used the choke (7H @ 150 ma DC) in place of the 1k resistor that connects the first and second nodes. The center tap for the OT is connected to the first node, Every thing else comes after the choke.

Cool! We're on to something! I'm pretty sure I've got another two section cap can in my stash. I'll try swapping that suspect cap out tomorrow and take a closer look at the power supply in general. I'll report back with my findings. Thank you for taking to time to check out your B15 for comparison. ...

There is no standby.

Here's the AC measurments at the filter nodes-
1 4.7 V AC
2 40 mV AC
3 5 mV AC
4 4 mV AC

Is the 4.7 volts AC at the first node a clue?

I just disconnected the NFB resistor and did not notice a change. I also tried using an alligator clip to bring it in and out of the circuit, to compare, and there's not discernable difference.

I feel like it's either a ground issue or the heaters are picking up some AC somewhere. Just struggling to figure out where.

Yes, I do. I've tried it to ground and tried eliminating it and using two 100 ohms as an artificial center tap. It's currently tied to the positive end of the power tubes cathode resistor / bypass cap. Looks like it's elevated my ground ref to about 34.8 volts DC.

Howdy Folks, I've built a single channel B15 clone that I need some help with. I have a 60Hz buzz that I'm struggling to identify. When I pull the preamp tube (V1) there's no change. When I pull the phase inverter tube (V2) the buzz goes away entirely. When I ground pin 4 of V2, the PI input, the bu...

Just to elaborate. The detail that I'm most concerned about it the clearance between the chassis and the speaker frame. Apparently it was even an issue on the originals. And seeing as how my cabinet and chassis are both based of measurements from original examples...........

Yup, I'm going to put together a drawing of the cab with dimensions for building. As well as the chassis dimensions. I'm just starting the actual build so I'm still working out the details myself. I'll post all the details before the treads done.

Sure, no problem.

Here is a PDF that is to scale. Take this over to a Kinko's or some place like that and have them print it to scale. The ring outside the speaker cutout it 15". You can use that for scale.

Nah, that would make it too much like a real job. I've been down that road and it gets old real quick. I'm mainly a guitar maker. I build amps cause I can't help myself. :lol: I've got a question for you guys. The original cabinet used block on all four sides to support the baffle. I'm thinking abou...

M Fowler wrote:Nice looking cab, great job on cutting out that baffle design.

I kind of cheated. My day job is programming and operating a CNC for a custom cabinet shop. I cut the baffle out the end of the day Friday.

mcrracer wrote:What material are you using? Can't tell from the pix although it does look like 3/4" something.

The box is 3/4 pine and the baffle is 1/2 baltic birch.

[IMG:1024:768]http://i211.photobucket.com/albums/bb138/jaydawg76/Thunderbolt%20clone/IMG_1875.jpg[/img] [IMG:1024:768]http://i211.photobucket.com/albums/bb138/jaydawg76/Thunderbolt%20clone/IMG_1876.jpg[/img] [IMG:1024:768]http://i211.photobucket.com/albums/bb138/jaydawg76/Thunderbolt%20clone/IMG_187...