The Amp Garage

The 220K mix resistors don't attenuate signal the way you think they do because there's no load involved. Well, there is a subtle filtering effect because the normal channel 220K is in series with a .047 cap and then in series to the AC ground of the power supply through a 100K plate load; audible,...

It is difficult for us to give any advice if you start with a modified baseline of a super reverb without the normal channel, so my advice is, go back to your baseline and correct the mistakes in your schematic. If you are still not happy with the result, the guys over here can give pointers in wha...

The 100K plate load resistors with the 1.5K cathode resistors is the gold standard for tube amps. It keeps the tube centered in a good operating window and should sound good. You could try a larger PI input cap like a .01, a lot of amps use a .1uF there. Try larger couplers on the power tubes like ...

M Fowler wrote:Why the 1m resistor into the bright cap? To reduce popping on the switch it should be wired different.

The 1Meg in series with the brite cap tames (to my ear) the tonal ffect of the brite switch. Makes it more useable for me.

When I mentioned lowering the plate voltages in the preamp I meant to either A) increase the value of the 7.5K resistor in the power supply string -or- b) put a 2W 150K resistor from power supply point "D" to ground. I am using a 250K reverb "mix" pot (audio taper) to make the reverb easier to adjus...

I measured all the resistors before I put them in. Plus, they are 1% metal film R's (mostly). The 100K carbon comp is real close to 100k (like maybe 99K or something like that).

Thanks!

here is a schem (caps marked with orange box are orange drop "PS" series caps. The 0.1uF cap in the tone stack is a Mallory 150. the 250pF cap i nthe tone stack is a silver-mica The rest of the coupling caps are Xicon MDD (I think they are polypro) caps. All R's are metal film 1/2W except for as not...

I designed and built an amp that is kinda like a super reverb, but with no tremelo, just one channel, and a tube recitfier. 2 6L6 output tubes, 2 12AX7's and two 12AT7 (PI and reverb driver). Anyhow, it basically works fine after I clear-up a few unconnected wires! But..the tone is somewhat lacking....

My first build! yey! I am trying to work-out a grounding scheme....Some questions have come-up. Why does Fender (mid 60's blackface) wire each output tube cathode to the chassis, right next to each power tube? Why not run each output tube cathode back to the place where the Power supply tranny secon...

picture this: 12AT7 reverb driver with both plates connected to reverb driver tranny primary. The other side of the primary goes through a 10K resistor to the "B" supply (Fender blackface "B" is "output" of the choke (i.e., the low side of the choke, as used). The old blackface and silverface schema...

I've seen a 10K in-series between the hi-V primary of a reverb driver transformer and the B+ voltage. Why is this resistor sometimes present in a reverb circuit? What does it do? Tonal advantage?

o.k...here I go exposing my ignorance.

What is a "T" fuse. Is that fast or slow,or something else.

I am building a Fender AB763 type of circuit (two 6L6, 4 triodes).

I want to ad an HT fuse to protect the output tranny. Is 1/4A sufficient (slow blow), or do I need 1/2A (slow blow)?

Thanks folks! I'm going to use a 250K log pot then. And, put 68k in parallel with it. That way, I get a ~50K load (equivalent to trem circuit 50k intensity pot) on the last gain stage before the PI. When that 50K load is missing I have found that I did not like the response/feel of the amplifier...t...

I am building a Fender AB763 style amplifier and want to include a master volume. What is the consensus of using a linear taper or audio taper pot for master volume? I am not using it as a way to get significant overdrive, but rather, just to allow me to get the preamp volume high enough (to get jus...