Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: hesamadman on December 16, 2017, 09:29:31 am
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After year of building only tube amps and years of playing only tube amps without FX loops.....I have recently been making fx loops mandatory in my builds. With me discovering how great an fx loop is for reverb and things of that nature, I started putting some overdrives in the front of the amp also. I came up with something that I really liked and wanted to make a pedal out of it. I have two tube screamers. I started using them both at the same time in series. Not in a very high gain setting. Just a light drive. But I keep the knobs on each pedal exactly the same. I really love this tone that I am getting so I decided to build a pedal that is just two tube screamers in one, but I would like to use dual pots so that level is one knob, drive is one knob, tone is one knob. The dual pot controls this in both sections. At the end of the chain, I added a 3 band tone stack. I dont know what this will be like yet. I plan to build a tone stack into a pedal project box and just put it in the chain with my two tube screamers to see what its like. I may not include it in my final build if I dont like the results I get when testing.
I am curious though. When using the dual pots to control two things that are kind of spread apart in the circuit, do I have to worry about noise the same way I would if I were doing this in a tube amp? I do not know much about pedals and was wondering if I should use shielded cable for this.
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Breadboard it first, then you can tweak it , experiment and so on, I don't see a problem ganging the controls in dual pots !
I like the idea !!
Here is my breadboard with a version of EQD Sea Machine , aka Gravity.
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After year of building only tube amps and years of playing only tube amps without FX loops.....I have recently been making fx loops mandatory in my builds. With me discovering how great an fx loop is for reverb and things of that nature, I started putting some overdrives in the front of the amp also. I came up with something that I really liked and wanted to make a pedal out of it. I have two tube screamers. I started using them both at the same time in series. Not in a very high gain setting. Just a light drive. But I keep the knobs on each pedal exactly the same. I really love this tone that I am getting so I decided to build a pedal that is just two tube screamers in one, but I would like to use dual pots so that level is one knob, drive is one knob, tone is one knob. The dual pot controls this in both sections. At the end of the chain, I added a 3 band tone stack. I dont know what this will be like yet. I plan to build a tone stack into a pedal project box and just put it in the chain with my two tube screamers to see what its like. I may not include it in my final build if I dont like the results I get when testing.
I am curious though. When using the dual pots to control two things that are kind of spread apart in the circuit, do I have to worry about noise the same way I would if I were doing this in a tube amp? I do not know much about pedals and was wondering if I should use shielded cable for this.
Usually on low current like pedals you do not have noise issues from layout, however I have had tonal shifts from breadboard to layout. Usually a 2 sided board will get it done as most noise is either from the power supply or a bad part.
The dual pot simply is setup to raise one wiper in value while turning and lowers the other. Look at the clone of a Klon as it has a mix dual pot. Mixes clean signal with a overdrive and another set of clipping diodes which come into play at enough gain.
Lots of people use 2 tube screamers and the idea is fine. I do not think I would want the same controls simply because rooms change and sound changes and you could get stuck.
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I am curious though. When using the dual pots to control two things that are kind of spread apart in the circuit, do I have to worry about noise the same way I would if I were doing this in a tube amp? I do not know much about pedals and was wondering if I should use shielded cable for this.
Shielded cable is generally not necessary inside of an effects pedal as long as the enclosure is made of metal (providing the shielding as guitar cables/chords do) and is grounded with the circuit and input/output jack's ground. If using cliff jacks then you must be sure that both sleeves are soldered to a ground point on either the board or DC power jack. Obviously the board must be grounded to the power jack as well or the effect won't work.
If someone uses a plastic, wood, or other material for an enclosure then shielded wiring would be a good idea - not on every control, but start out shielding the input/output jacks especially to the 3PDT switch and from the switch to the input/output parts of the circuit board.
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Original poster,
If you are building this 2 tubescreamers with a TMB Eq, you are essentially building a "Marshall the GuvNor" pedal. This is also the basis of the boss blues driver (it has TMB EQ set in the circuit), and the JHS charlie / Andy Timmons model.
The boss and jhs use jfets to mimic opamps, but I believe the guvnor uses opamps.