Hi guys!
This is my first post here 🙂
So, I have a problem and I think going DIY is the only way to solve it without spending +$100.
I have a guitar amp with a +4dB serial FX loop. The ideia is to use it with a Lexicon PCM81. However, to avoid AD/DA conversion, I bought 2 splitters like this:
I put one into the FX send and the other into the FX return. Then, I put a cable linking then together (this would be the dry signal). I made several tests and the tone was intact. However, when I insert the PCM81 into the chain using the remaining I/O, all I got was a terrible noise.
How can I solve this? I have solder experience, but never built a circuit! Maybe this is the right time to start!
This is my first post here 🙂
So, I have a problem and I think going DIY is the only way to solve it without spending +$100.
I have a guitar amp with a +4dB serial FX loop. The ideia is to use it with a Lexicon PCM81. However, to avoid AD/DA conversion, I bought 2 splitters like this:
I put one into the FX send and the other into the FX return. Then, I put a cable linking then together (this would be the dry signal). I made several tests and the tone was intact. However, when I insert the PCM81 into the chain using the remaining I/O, all I got was a terrible noise.
How can I solve this? I have solder experience, but never built a circuit! Maybe this is the right time to start!
You left the jumper dry in place? SO you did not notice that this connected the Lexicon input to its output? Remove the jumper cord, now how does it sound?
WHy does AD/DA worry you in a guitar amp?
WHy does AD/DA worry you in a guitar amp?
When I use the jumper only the sound is fine. When I use the Lexicon only it's fine too. I didn't know using both would connect the Lexicon input to its output. The ideia was to use the way I saw in this video:
https://www.youtube.com/watch?v=z3aqZSywx7k
Skip to 1:30.
The AD/DA stage in those vintage racks don't preserve the original signal very well. I used to have a Sound Sculpture Switchblade in the past to do that, but sold it to pay some bills.
Racks+mixer is the way people used to do back in the days (check Landau, Lukather, etc).
Doesn't the Lexicon allow you to dial up an (internal) dry-wet mix?
The problem Enzo pointed out can be fixed quite simply with a potentiometer and a resistor or two, but if you have to go out and buy a soldering iron, solder, tools, etc, that is not an economical solution.
Also, you may then find another problem, related to the phases of the two signals. Depending on the internal workings of the Lexicon, it is possible that it will cause bass cancellation or other nasties when mixed with a direct signal.
Some sort of small two-input mixer (preferably with an "invert" button on at least one channel) does seem like the best solution for you.
Here are two quite inexpensive solutions that should work, if you are okay with Behringer gear. Both are under $35 USD:
Behringer Xenyx 502 | Sweetwater.com
Behringer Micromix MX400 | Sweetwater.com
-Gnobuddy
The problem Enzo pointed out can be fixed quite simply with a potentiometer and a resistor or two, but if you have to go out and buy a soldering iron, solder, tools, etc, that is not an economical solution.
Also, you may then find another problem, related to the phases of the two signals. Depending on the internal workings of the Lexicon, it is possible that it will cause bass cancellation or other nasties when mixed with a direct signal.
Some sort of small two-input mixer (preferably with an "invert" button on at least one channel) does seem like the best solution for you.
Here are two quite inexpensive solutions that should work, if you are okay with Behringer gear. Both are under $35 USD:
Behringer Xenyx 502 | Sweetwater.com
Behringer Micromix MX400 | Sweetwater.com
-Gnobuddy
Thanks for your help!
I work building pedals boards and racks, thus I have a solder iron! I just need some instructions🙂
Well, the simplest way to avoid the problem Enzo pointed out, is to use a couple of fixed resistors to mix the two signals together (output of the Lexicon, and the dry signal). In this way, you avoid shorting out the Lexicon. You make mix adjustments using the Lexicon's output level control.
The super-simple solution may work for you, or it may not; I don't know the output impedance of your "FX send" source, or the input impedance of your "FX return" jack. And there is also the possible phasing error.
But I took a stab in the dark, and the schematic is attached. You can still use the splitters you have. Just make up two short cables with a resistor inline with the "hot" wire of each. One of those cables carries the "dry" signal from one arm of your "send" splitter, to one arm of your "return" splitter. The other cable carries the Lexicon output to the second arm of your "return" splitter.
The thing is, by the time you add up the cost of the splitters, 1/4" plugs, wire, and resistors, you won't save much compared to the little $25 Behringer...and you'll have less flexibility. And, though it will prevent the Lexicon output being shorted to input, it may not provide the mix you want.
-Gnobuddy
The super-simple solution may work for you, or it may not; I don't know the output impedance of your "FX send" source, or the input impedance of your "FX return" jack. And there is also the possible phasing error.
But I took a stab in the dark, and the schematic is attached. You can still use the splitters you have. Just make up two short cables with a resistor inline with the "hot" wire of each. One of those cables carries the "dry" signal from one arm of your "send" splitter, to one arm of your "return" splitter. The other cable carries the Lexicon output to the second arm of your "return" splitter.
The thing is, by the time you add up the cost of the splitters, 1/4" plugs, wire, and resistors, you won't save much compared to the little $25 Behringer...and you'll have less flexibility. And, though it will prevent the Lexicon output being shorted to input, it may not provide the mix you want.
-Gnobuddy
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Amazing! Thank you veru much for this man! I'll try and come back latter with results 🙂
This mixer is expensive in my country!
I've searched before posting here and I found the perfect solution: Splitter-Blend
However, it seems to complicated for my skills and I've read some people complaining the schematics isn't correct.
This mixer is expensive in my country!
I've searched before posting here and I found the perfect solution: Splitter-Blend
However, it seems to complicated for my skills and I've read some people complaining the schematics isn't correct.
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Ah. Silly me, I didn't think of that. 🙂
Electronics things are much more expensive here in Canada, too, compared to the USA. But I know that the same things are really expensive in some other countries.
It may be a bit more complex than necessary, and has the same kind of passive mixing (two resistors) I showed you. Since the circuit uses multiple opamps, they could have come up with a better (active) way to mix the signals.
But that circuit does have a phase-reverse switch (good). And presumably someone already built and tested that it works, and that's good, too!
I didn't spot any errors, though I didn't check all the IC pin numbers.
When you have the time, you could always build your skill level by building a simple guitar effects pedal - very close to what you already do, and probably a useful skill to add. 🙂
-Gnobuddy
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