![bk butler tube driver schematic bk butler tube driver schematic](https://images.reverb.com/image/upload/s--yErMQyyB--/t_card-square/v1598861390/prxn77uuntzqeskfal9i.jpg)
That had a different tone from the stock tube. For a while I had a NOS Sylvania ECC83 in there. I bought this Blue Tube new when they first came out. It's not a very loud hum, but it's enough to be annoying. I'll give it a try and see if the hum is any different. And I can still get plenty of overdrive and distortion. With the 12AU7, I can crank the gain up and get a nice clean warm tone. So when I turned the gain up to get the pedal to unity gain, it would be too distorted. Since the 12AX7 has an amplification factor in tension decidedly higher than the AU (is more sensitive), if the hum is due to the AC (which is applied close to the pins of the grids) should hear more strongly when it is mounted the AX.The reason I'm using a 12AU7 is that when the pedal was set to sound clean, the output level was too low. For the rest it seems to me a pattern that deserves to be studied, because if it sounds good as you say. Maybe they forgot to mark a capacitor?Īlso in the tone stack there are two words "220K" and "500K" in close vicinity to the same pot. Still, there is an inscription ".01" close to the tone stack that you do not understand what it refers.
![bk butler tube driver schematic bk butler tube driver schematic](https://www.musikding.de/media/image/product/9961/md/mosfet-driver-kit.jpg)
Only 12pF in the DRIVE control? Or wanted to write "120"? Mozwell: Thanks for the info! It 'a very interesting pattern, but there are some ambiguities that do not understand. I wonder if it might fit the pattern of the Tube Screamer, without having to use another IC? It seems to me an excellent idea of the output buffer. However, this AC is 1.6 A RMS, and then tends to disturb the other signal tubes of the circuit, if it is not the screen. The 6550, as is normal in the power tube, has an amplification factor in tension rather low, so it is not very sensitive to the induced AC hum of the heater. I have done so for the heaters of 6550C in a single ended amp like the ace of "picche" of my avatar (equipped with a 300B tube). The shield seems to me a good idea does not do much weaving together the wires that carry the current to the heaters, you may instead use two shielded cables (coaxial). Since the 12AX7 has an amplification factor in tension decidedly higher than the AU (is more sensitive), if the hum is due to the AC (which is applied close to the pins of the grids) should hear more strongly when it is mounted the AX. To be sure that the hum is caused by the heaters, I'd suggest comparing the buzz with the 12AX7 and the 12AU7. Why not try it on your Blue Tube the 12AY7?
![bk butler tube driver schematic bk butler tube driver schematic](http://www.in2guitar.com/driver/driverfrontsm.jpg)
David: Hi, You are very kind! In fact, I'd like to know what are the tensions on the 4558 at least as the TL072.