Can anyone point me in the direction of a basic high impedance signal splitter example that uses tubes? Let's say I want to split a guitar signal in two using a standard double triode, or a single even, to go into two different amps. Power supply and phase issues don't need to factor into this (yet). I am pretty sure I can just use resistors after the plate, or even I guess a cathode out, but I would rather see how others have done it before I slap something together willy-nilly.
Thanks for any advice given 🙂
Thanks for any advice given 🙂
You may get more information in the Instruments and Amps section, may be called a Direct Box, but probably all that's needed is some wire and paralleling the guitar's output. Whatever you do, ground loops will be an issue, so start by plugging everything into the same power distribution strip and test the mains outlet everywhere you go for safe wiring. Trust but verify.
All good fortune,
Chris
All good fortune,
Chris
Di boxes are very common, and always SS. I wanted to stay away from the instrument area so it didn't get watered down with those suggestions.
Why use a double cathode follower, and not a DC coupled cathode follower and split the signal after? Then there would be a little bit of interesting compression and some possibility of a bit of gain if needed for the next stages. I think....
Why use a double cathode follower, and not a DC coupled cathode follower and split the signal after? Then there would be a little bit of interesting compression and some possibility of a bit of gain if needed for the next stages. I think....
All you need to split the signal is a couple of pieces of wire! In other words, a Y-cable. There is no need for an active circuit of any kind...
A y splitter will cause signal loss from a high impedance source, like a guitar, so that option is less ideal. It has been tried, and functionally works, but I would prefer to make an active splitter/buffer.
The outputs will both be very very short cables. This splitter will be integrated into the unit and will be going to the grid of a pentode on each channel.
I would use two cathode followers with their inputs in parallel, each driving only one amplifier, to prevent interactions between the amplifiers. Depending on the precise design, signal level and driving impedance, switched-off solid-state amplifiers can distort their input signals grossly. Hence, if one of the two amplifiers could be such a switched-off solid-state amplifier, you either have to keep them from influencing each other, or disconnect the switched-off amplifier, or decide that you find the distortion artistically pleasing.
If they're guitar amps then they will be high impedance, so the loss is minimal. But it's your show.
Is it so conceptually difficult? Take a single triode input stage from you favorite tube guitar amp. Duplicate it. Connect both inputs to the same 1/4" TS jack, through the "grid stop" resistors or whatever network they put there. Perhaps a dual pot loading the plate DC blocking capacitors. Outputs from the pot wipers to ground.
Of course, component specific values are up to the original schematic and your own choice.
Merlin, somehow you make things oddly clear. I was under the impression that a guitars high impedance would make losses more significant, and was battling this by looking for an active splitter Thank you.
The rabbit hole t has taken me down now though has brought up questions for another day though.
'High' is a relative term.
A guitar is high impedance, compared to most other bits of gear that is.
But a guitar amplifier is designed to be even higher impedance for exactly that reason.
So you can run a guitar into two amps and still get away with it.
Obviously that cannot continue indefinitely; splitting into three or four amps might be asking too much and you would then be looking for a buffer.
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How about the cable capacitance? Two amplifiers presumably require more cable than one, and the source inductance is several henry.
Hopefully the longer cable goes to the guitar, a much shorter one between amps. Of course with musicians, they might buy two of the same length and just plug 'n play.
Even being an engineer, I have no idea how multiple Marshall stacks were actually wired, given that all on stage were on and in use. So I'm not so smart. Perhaps the amps "effects loop" output came in handy for that.
Well you denigrate the IA forum, but at least there you would have been told the thing you are trying to build is an ABY pedal and not a DI box. Usually the highest priority in a higher end ABY pedal is to break the ground loop you will create if you Y two amps. You can actively buffer but this is a lower priority.
OK, and in electronics terms, what is an ABY pedal? Is a passive ABY pedal a signal transformer with a rather large inductance that has two secondary windings, and an active ABY pedal some electronic circuit that behaves similarly, in the sense that it also distributes the signal and breaks ground loops?
If so, I built an active ABY pedal for moving-magnet turntables a decade or two ago without even knowing it 😉
If so, I built an active ABY pedal for moving-magnet turntables a decade or two ago without even knowing it 😉
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