Magnetron Tape Echo Simulator (Halogen Wolf)

[farwest1]

My eighth build, the fifth from PedalPCB. Sounds amazing. Here's a sample. I changed the name to the Halogen Wolf Decay Delay. Part of the fun for me in building pedals is naming and creating graphics.

The build went smoothly. I made a few small mods to the pedal. I added the Gain trimmer as a B100K pot to the face of the pedal, which was a good move. (I'm not a huge fan of internal trimmers. I'd rather just have all the variables on the face and easily adjustable.)

I also swapped out the A100K Feedback pot for a B100K, which gives it a nicer ramp. The logarithmic pot tended to not give enough audible repeats until well after 12 o'clock. The only issue with the linear B100K is that it goes into self-oscillation well before the knob is maxed out, so I have to be really careful not to overdo it or I'll blow speakers and eardrums. I messed up the LED for the LFO by accidentally filling it with solder and then not being able to remove it. So I think I fried the pad—the LED doesn't work.

Also (my one complaint with the pedal) the "wet" level never achieves unity with the "dry" level. I do wish there were an easy wet/dry pot mod for this. Maybe someone could let me know if it's possible. It would improve the pedal a lot I think.

For the enclosure, I used a white waterslide in order to get white graphics on a black background. It's a pretty clunky process, never as smooth as I'd like. I then sprayed it with hologram glitter paint. Looks great in person. It sparkles in the light. The white knobs are the modulation elements, the black are delay elements.

The name comes from a weird little cyberpunk story by William Gibson called "Academy Leader". I remembered it from an anthology I owned back in the 1990s:
"in the hour of the halogen wolves, in radio silence."
Seemed appropriate for a decaying, warbling delay.

 

[cooder]

Excellent build, looking great and pro to the top!

 

[Ralfg]

Pedal looks great! I really like the decal and spray turned out.

To make the wet signal louder you could try reducing R10.

 

[farwest1]

Pedal looks great! I really like the decal and spray turned out.

To make the wet signal louder you could try reducing R10.

Thanks! I will try it.

what do you think it would take to add a wet/dry knob to this circuit? Would it involve retooling the circuit itself?

 

[phi1]

Did you try increasing R12 like was mentioned on the other thread, or decreasing R13 (similar to reducing R10) yet? Personally, I wouldn't want a wet dry knob since there's no volume knob, better to just bring up the delay signal to where you want it in my opinion, rather than end up with the dry signal quieter than unity. Also have you checked with anyone else who's built it to see if they have the same behavior?

 

[Ralfg]

Thanks! I will try it.

what do you think it would take to add a wet/dry knob to this circuit? Would it involve retooling the circuit itself?

I think a wet dry knob would have to look something like the Madbean Florist’s blend knob.
Florist Schematic
It would not be an easy change on the exiting board.

I think if you change R13 or R12 that would also change how quickly the repeats start to oscillate, which might be what you are looking for.

I agree with phi1, I’m not a fan of mix knobs on delays. You could though pull out R6 and put a switch there that just disconnects the 10k to make a dry kill switch.

 

[Barry]

Looks and sounds great!

 

[steelplayer]

Great looking build! Love the Hologram Glitter Paint and the concept!

 

[farwest1]

Did you try increasing R12 like was mentioned on the other thread, or decreasing R13 (similar to reducing R10) yet? Personally, I wouldn't want a wet dry knob since there's no volume knob, better to just bring up the delay signal to where you want it in my opinion, rather than end up with the dry signal quieter than unity. Also have you checked with anyone else who's built it to see if they have the same behavior?

Thanks! So is the Level knob in this pedal a wet-signal (delay) volume knob, and the dry signal remains constant?

What I'm looking for, then, would be a louder final wet signal. I have another delay that allows me to go full wet (cuts the dry altogether). I love it, because I can use it all kinds of untraditional ways: swelling modulated repeats, ghost repeats, stuff like that. Sometimes I want the initial dry signal out of the mix completely.

 

[phi1]

yes the level knob on the magnetron only controls the wet signal, the dry is constant. If you had a blend knob, I think you'd also want a volume (master) knob as well. Another option would be to have a separate dry level knob, and a wet level knob. In both these cases you'd end up with a different pot layout, so I'm guessing you'd do it in a new build instead of modding this one.

I do think you could wire the level knob like a wet/dry blend instead, but it would involve rerouting a few components, so it would also be better suited to a new build than modding this one (in my opinion).

 

[Chuck D. Bones]

Very nice build!
You can trim the maximum amount of feedback by increasing R8 or R9. I think R8 is the better choice. If you reduce R13 to bring up the wet level, you will want to adjust R9 upward. You can also reduce the maximum signal in self-oscillating mode by changing D1 & D2 to Schottkys.