The idea comes from reading an article about multi-tracked guitar recordings. ("How to get a "fat" guitar sound")
Probably a "just for fun" idea.
I started wondering - Could a guitar tube amp circuit be designed to split the signal and process each side just a little bit differently?
I think the most obvious answer would be dual single-ended design with individual OT windings.
Is there another way? 18 watt Marshalls have a parallel configured V1. That seems to help just a tiny bit. What if you just kept paralleling preamp valves? Surely someone has attempted that?
What if (in push-pull configuration) you split the signal before the phase inverter and filtered (high-pass, low-pass, band-pass) just one side?
I wouldn't want a dramatic change but I'm still curious about anything that could make the guitar sound fuller without also introducing strange effects (like flanging).
Probably a "just for fun" idea.
I started wondering - Could a guitar tube amp circuit be designed to split the signal and process each side just a little bit differently?
I think the most obvious answer would be dual single-ended design with individual OT windings.
Is there another way? 18 watt Marshalls have a parallel configured V1. That seems to help just a tiny bit. What if you just kept paralleling preamp valves? Surely someone has attempted that?
What if (in push-pull configuration) you split the signal before the phase inverter and filtered (high-pass, low-pass, band-pass) just one side?
I wouldn't want a dramatic change but I'm still curious about anything that could make the guitar sound fuller without also introducing strange effects (like flanging).
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But seriously, I'm just being curious. I once read about an interesting single-ended amp with three different power tubes. It was called the Palmer Drei iirc. That's a pretty cool idea too. What makes it interesting to me is the all-in-one package.
I do like paralleling triodes, to the extent that if I build a circuit that only needs two 12ax7s but have a chassis with slots for three, then I'll use parallel triodes for the first two stages. If you want to keep the same gain, you half the associated resistor values and double associated capacitor values. The Miller capacitance is doubled though, so you have to think carefully about grid stopper values. The noise level is reduced quite a bit compared to the equivalent-gain single triode stage. To me they do sound a bit 'warmer' but I'm not sure why that should be (except perhaps the Miller capacitance and the lower background noise).
Of course, if you follow the rules on grid leak you need to change the usual 1M at the input stage to 500k (when it has two 12ax7 triodes in parallel) which is still a reasonably high input impedance, but will load the guitar pickups more - again contributing to a 'warmer' sound!
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I once had a combo amp called the Ultraflex, made by the Audio Crafters Guild. It was also sold under the Magnatone name.
There was a single preamp with reverb and tremolo and the Ultraflex knob that split the signal to two different power amps in varying amounts. Both power amps used 7591 tubes for about 25 watts each. One power amp used a smallish OPT and fed a 10 inch open backed cabinet. The other amp had a bigger OPT and fed a 12 inch speaker in a complex closed back multi chambered enclosure.
I left the amp behind when I had to leave Florida on rather short notice, but I intend to build something like it eventually. It had a bluesy tone that could not be forgotten.
There is very little info on the amp, and I never could find a schematic for it anywhere.
There was a single preamp with reverb and tremolo and the Ultraflex knob that split the signal to two different power amps in varying amounts. Both power amps used 7591 tubes for about 25 watts each. One power amp used a smallish OPT and fed a 10 inch open backed cabinet. The other amp had a bigger OPT and fed a 12 inch speaker in a complex closed back multi chambered enclosure.
I left the amp behind when I had to leave Florida on rather short notice, but I intend to build something like it eventually. It had a bluesy tone that could not be forgotten.
There is very little info on the amp, and I never could find a schematic for it anywhere.
@malcontent Irving.
Your after-thought is my oversight. I'm pretty sure I have 1M. I should change that.
@tubelab
That is exactly the sort of thing I'd love to know more about. It sounds like an awesome project.
@Jonsnell - and that's another interesting idea.
I'm not sure where this could go, but it seems worth thinking about.
Your after-thought is my oversight. I'm pretty sure I have 1M. I should change that.
@tubelab
That is exactly the sort of thing I'd love to know more about. It sounds like an awesome project.
@Jonsnell - and that's another interesting idea.
I'm not sure where this could go, but it seems worth thinking about.
Line 6 Duoverb. Yamaha THR100D. Stereo amps in which you can basically assign an individual amp per each channel. I'm sure there are other similar setups.
If we go way, way back an ancient trick to get "fatter" tone with "vintage" -style dual channel amps was simply feeding input signal to both channels simultaneously.
Those were early examples of "bi-amping" setup: Separate power amplifiers for lower and higher frequencies, crossover somewhere around mid-range. Decreases intermodulation distortion because due to separate amps distortion at low frequency band will not effect reproduction of higher frequency band, or vice versa.
If we go way, way back an ancient trick to get "fatter" tone with "vintage" -style dual channel amps was simply feeding input signal to both channels simultaneously.
Those were early examples of "bi-amping" setup: Separate power amplifiers for lower and higher frequencies, crossover somewhere around mid-range. Decreases intermodulation distortion because due to separate amps distortion at low frequency band will not effect reproduction of higher frequency band, or vice versa.
Autocorrect I presume! But I do like it - I might start using it myself.
Malcolm Irving
Three is used as an example. You can use three chained delays or phasers, each set slightly differently, into a single amp. You're just trying to simulate the small phase or time differences between three otherwise identical magnetic tape tracks. Parallel hookups are not required just because of tape head topology.
Use the least hardware possible unless you'd like it to look impressive.
With a decent DAW you'd need no other hardware.
Parallel input devices is just a way to lower the stage noise by lowering the stage impedance. It's normally done on the 1st preamp stage only because that sets the noise floor for the system.
Use the least hardware possible unless you'd like it to look impressive.
With a decent DAW you'd need no other hardware.
Parallel input devices is just a way to lower the stage noise by lowering the stage impedance. It's normally done on the 1st preamp stage only because that sets the noise floor for the system.
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That's true, but if you play with the vol. control set very low (and that pot. is in the usual position between first and second stage) then all the gain from the first stage is thrown away and the noise floor is coming from the 2nd stage.
The simplest way to do what you originally suggested is just to make a pseudo- stereo phase shifter circuit to feed one of the channels. You can just google pseudo-stereo to see circuit ideas.
I have to say that all these ideas are not really how professional musicians go about this, since you brought that up originally. They typically do what JMFahey said. They typically use either dry/wet or wet/dry/wet channels using A/B or A/B/C boxes and loopers. I would recommend that instead of pursuing these novel or one-off ideas as suggested, you simply start DIYing more conventional musicians solutions. An A/B box and and looper would serve you well, and are easy DIY projects.
I have to say that all these ideas are not really how professional musicians go about this, since you brought that up originally. They typically do what JMFahey said. They typically use either dry/wet or wet/dry/wet channels using A/B or A/B/C boxes and loopers. I would recommend that instead of pursuing these novel or one-off ideas as suggested, you simply start DIYing more conventional musicians solutions. An A/B box and and looper would serve you well, and are easy DIY projects.
I had the same conversation with my best friend last night. He asks me why I don't just build what works.
The only answer I can give is that it seems more interesting to me. I could build a really nice clone of any particular amp, but I'm more interested in understanding the design process.
I've always been more fascinated by the wrong answers. It's easy to copy things that work, but -for another example - could I get some kind of a tone advantage from using a transformer phase inverter?
Price and weight are disadvantages - granted - but is that all? I'm not building a production line here. Making something novel could be a lot cooler.
The only answer I can give is that it seems more interesting to me. I could build a really nice clone of any particular amp, but I'm more interested in understanding the design process.
I've always been more fascinated by the wrong answers. It's easy to copy things that work, but -for another example - could I get some kind of a tone advantage from using a transformer phase inverter?
Price and weight are disadvantages - granted - but is that all? I'm not building a production line here. Making something novel could be a lot cooler.
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