The Amp Garage

Use an audio pot for the volume and a linear pot for the tone. I just finished a build based on this preamp circuit and I can say that a linear pot for the tone control is the way to go. With a linear, the mid point of the pot is really close to being the mid point between bass and treble, which is ...

You took all the tone-meister caps out and replaced them with leaky caps? Please work on some old Marshalls and take out all the mustards and send them to me.

I would wait and get a 6V6. Buy a pair, then you have a spare.

Hey, I'm a poet!

Did you try swapping in different tubes? I have had brand new tubes (not NOS) that arced internally right out of the box.

Voltage readings would be helpful.

Lift one end of the 22K resistor that connects to the 1k5 resistor and is in between the 25uf cap and the .022 cap. One end of that 22K goes to the speaker jack.

Does it still do it?

Well, I ain't smart, but I have an opinion.

You can also switch the screen grid resistors to the plates. Check out some of the Marshall JCM900 schematics--that's what they did for the half power switch. What it does it switch the tubes from pentode mode to triode mode.

Off is Off. There are 4 poles and one common. You can select None--1--2--3--4.
This won't do what you want. You need a single pole, 5 throw switch.

This one would do it: http://www.grainger.com/product/NKK-Rot ... =P2IDP2PCP

10 mv. is quite low. If you are wanting to get a signal that is about the same level as a guitar pickup, use 100 mv. That is about a "vintage" pickup level. 150 to 200 mv. is in the range of the hot pickups.

Because you are biased very cold--meaning close to class B if not already in class B. The tubes are only a volt or two away from cutoff. You don't have a 15 volt range available on both sides of the bias voltage.

How did you come up with this configuration? Why 200 volts? Why 6k6 OT? Why biasing at less than 25% plate dissipation? Why KT88 tubes? None of your choices make any sense to me and I would be interested in why you made these choices. If you were going to use a KT88 with 200 volts on the plates and ...

I would never do anything like that! If I had done something like that, I would have a story to tell about how the end of the cap popped out and scared me so much that I jumped and made contact with the B+ rail and got the jolt of my life and then the amp fell off the cradle and broke a tube which w...

First, are you sure it is the power tubes that are clipping and not your phase inverter? Your numbers don't make sense. With 15 volts of bias across the 460 ohm, I get 32 ma. not 55 ma. Then, when calculating the wattage, (200 - 15) * .032 = about 6 watts. These are a 42 watt tube and you only have ...

I don't know how it would be for your application, but I really like the Cannabis Rex in a small 1*12 combo and in a 1*12 closed back cabinet. It just seems to have a smooth tone. I can imagine that it would be something to try in a 2*12 and a Rocket or Express.

I can appreciate the amount of time it takes to trace out a circuit to create a schematic and I am also sure that you did your best. Really, I don't have the time right now to give you any help with this other than to say, there are a lot of errors in it--I don't know what the schematic should be, b...

Before you start doing any mods, I suggest you verify your schematic. I see a lot of errors in it--unfortunately, I don't have the time to point them all out.