The Amp Garage

I didn't think it was that bad considering this was my first build, and I don't do this kind of thing often. How/what could I improve for the next build? I didn't mean to denigrate your workmanship, my comment was just about the use of terminal strips and their somewhat random placement and spacing...

I bought the 68k just in case i had to do that. already swapped the 100 for the 470 as the plates were glowing red as per the schematic suggestion. so v2 in parallel would be 1 and 6 together, both anodes? Plate: 1 to 6 Grid: 2 to 7 Cathode: 3 to 8 and, if not already, Heater: 4 to 5. I don't under...

That layout won't win any awards for neatness

Isn't one of the Red wires from the power transformer going to the wrong place ? Looks like it doesn't go to one of the diodes like it should.

Amwatts wrote: ↑Fri May 05, 2023 11:28 pm Here it is , I really like the 2M input , over the standard 1M ...

As drawn, the input impedance is 63.9K on either input.

V2 pins 1, 2, and 3 are a dc coupled cathode follower. Those voltages are normal. I shoulda looked at the schematic. Some tubes are not up to the task with the 56K cathode resistor. Try a different 12AX7 or a 12AT7 to see if that stage is choking off the gain. Another thing to try is just wire the ...

Isn't V2 a cold clipper ?

V2 1 2 3 4 9
187 108 108 0 0

Those Voltages don't seem right. Maybe the 10K from pin 3 to ground is wrong or missing. Maybe a short 2 to 3 and no 10K ?

FYI: AC Voltages should read zero on a meter set to DC Volts.

Tell them you have to know the manufacturer and the details of the materials used for recognition by Underwriters Laboratories.

Don't use the word "Approval", UL doesn't like that word. They call it UL recognition.

Check that you have an extra couple of Amps of heater current available from the PT.

I do get loud clicks as well as the oscillation, speaker jacks read .5-.6 ohms, The output transformer is 1750Q Hammond, wired with the orange common wire from the secondary to the sleeve of the speaker jacks, yellow to the 4ohm out labeled terminal 1 on the impedance switch, green to the 8ohm 2nd ...

All the Voltages in post 1 look good. With all pots set to 5, touching a DVM probe (other probe grounded) to the Grids (pins 2 or 7) of the 12AX7s should produce a clicking or hum through the speaker. Touching 2 and 7 of the PI should produce loud clicks. I can't help but think you may have a short ...

Looking forward to seeing your layout. I like the one tube near the inputs and pots and the other near the power tubes.

The cold clipper is always going to pop because you are changing the bias even if you arrange the switch and resistors to eliminate the dead zone where cathode current falls to zero. (Hook the resistors in series and short the ones you don't want to select.) One long way around it is to have four se...

I suspect miss wired input or speaker jacks. Ohm checks with power OFF. Plug a cable into one of the speaker jacks. Ohm across the free end of the cable. You should see a very low reading close to zero. Plug a cable into one of the input jacks. Measure Ohms across the free end of the cable. You shou...

In the USA there is supposed to be a ground wire at the power pole connected to that center tap of the 240V. Each "customer" is supposed to also ground the center tap at the incoming breaker panel. In my city, they caught a guy that was going around to power poles cutting off the safety ground (it's...