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Post by geo on Aug 3, 2023 11:52:21 GMT -5
I have a KORG SP-280, which I'd like to plug into some effects pedals. It has a line out and headphone out jack, both of which are definitely already amplified, but I imagine it has to be weak enough to put into guitar effects pedals, yeah? After the pedals, I would guess I just need an amp on very low gain? Or should I try going right into a mixer and then monitor?
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Post by newey on Aug 3, 2023 12:58:36 GMT -5
The problem will be the impedance mismatch between the line-level output (which is balanced) and the instrument-level (unbalanced) input of your amp. I doubt whether you'd hurt anything with the amp at low levels, but it probably wouldn't sound very good. There are line-level to instrument-level converters. Many more go the other way, from instrument level to line level, so a guitar can be plugged into a PA, but some do go line-to-instrument, and some go both ways. If the line out is an XLR connection, you could probably use one of these: www.guitarcenter.com/Livewire/Essential-High-Impedance-Transformer-Adapter-1-4-TS-to-XLR-Female-1500000013103.gc?cntry=us&source=4WWRWXGP There are also "reamping boxes" that will do the trick but those will be considerably more costly. |
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Post by sumgai on Aug 3, 2023 15:53:09 GMT -5
geo,
The short answer to your query is that, yes, it's safe to plug things in like you decribe.
Where you'll find that the results are not what you wish is as newey describes - impedance mismatch. But will such a thing cause damage? Nope. Unless we're speaking about amplifier outputs greater than a watt or two, then impedance mismatches only create horrible sounding results.
Usually, and this isn't always true but usually, one wishes to feed low impedance into high impedance. For that reason, most devices have low impedance output (particularly headphone jacks), and most devices have high impedance inputs, on the order of several hundred Ohms, and as high as 100KΩ. Guitar pickups are often the exception here, a nominal "standard" single coil can run from 4KΩ to 15KΩ, and a few humbuckers have gone even highers. So amp inputs are often rated at greater than 50KΩ, and sometimes run to double that figure.
Likewise, pedals are built to roughly those same standards - high input impedance, low output impedance. So again, you won't damage anything (except possibly your sanity) by hooking things up as you think they should go. But if the final sound isn't up to Mojo Tone™ standards, then you're going to need something like newey suggested, an impedance converter.
HTH
sumgai
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Post by JohnH on Aug 3, 2023 16:32:36 GMT -5
I had a look at the Korg manual, which shows there are two line-out jacks, for left and right, and if you use just the left, it will mix to a mono signal.
So you can use a normal instrument cable from there to plug into a guitar pedal. Guitar pedals are designed to have a high-impedance input (so direct from a guitar works properly), and give a low impedance output. But often, the next pedal is getting its input from the low impedance output of a previous pedal, and that's all fine.
The other parameter in play is voltage output. The signal voltage level from a guitar or a pedal is not too far different from that of line level, which the Korg is making.
So I reckon it'll work, using the left=mono output. Use the volume control on the Korg to start low and build up carefully to find the right level.
Last thing to watch out for may be ground loops, when you link your pedal and amp chain to the Korg. Not a safety issue but listen for any excessive buzzes and hum. If not it's ok.
As an alternative, line out to mixer to PA or monitor is another output option. I've also used guitar effects within a mixer Aux send-return loop.
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Post by unreg on Aug 4, 2023 9:23:47 GMT -5
Last thing to watch out for may be ground loops, when you link your pedal and amp chain to the Korg. Not a safety issue but listen for any excessive buzzes and hum. If not it's ok. A way to solve ground loop noise is to remove the ground loop. After plugging all of my guitar electronics into a single power strip, the terrible noise vanished. A key helper with that is my Truetone 1 SPOT Slim 9V DC Adapter recommended by my grand Sweetwater Sales guy. www.sweetwater.com/store/detail/1Spot9v--truetone-1-spot-slim-9v-dc-adapter/reviewsIt allows *up to 20 pedals, but I think I’ve only got cords for like 6 5 pedals, to be powered using only one outlet on my power strip. They also have a $$$ PRO version, but this one works great for me. EDIT: Want to note that the Truetone adapter does not come with any cables; so, it’s not just $19.99; I believe I purchased this 5 cable pack: www.sweetwater.com/store/detail/1SpotMC5--truetone-1-spot-multi-plug-5-cableIf anyone is interested, there are a few cable options… search “Truetone” and scroll down.  |
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Post by thetragichero on Aug 4, 2023 9:52:04 GMT -5
as a word of caution, i would start with the piano output volume on the low side and bring it up until it's loud enough but before distorting the sound. line level for audio gear generally means an output of 1 V. guitar pickups are generally on the order of a couple hundred milliVolts so effects designed for a guitar level input might distort on the input stage when used with a line level input, so best practice is to bring the source (ie piano) volume up slowly
that being said you won't break anything so have at it
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Post by ashcatlt on Aug 4, 2023 10:10:25 GMT -5
But often, the next pedal is getting its input from the low impedance output of a previous pedal, and that's all fine. Yeah I can’t believe newey and sumgai even went there with that. It’s a non-issue and they should both know better. This specific argument is one that I try to use when people start babbling about “reamp” boxes to “match” an audio interface output to an amp or pedal input. Do we put reamp boxes between pedals? No. Why? Audio “engineers” don’t know because they’re not Electronics Engineers anymore. They heard something about impedance once, didn’t understand it, and just keep parroting the same nonsense. In fact, I just yesterday commented on a vid from CS guitar where he was talking about Richie Blackmore running his guitar through a tape machine as a preamp before his amp, and this dude used a reamp box between them! I’m like, yeah I bet Blackmore didn’t have any such stupid thing. Impedance is not an issue…. …except your Fuzz Face probably won’t sound right because the source is not inductive so you won’t get the lowpass action from connecting a guitar to a “too low” inZ. In fact, the source is probably capacitive, so you might get a bit of highpass action instead. Probably not much, though, because “too low” for a guitar is still pretty high for something like a line input. Impedance isn’t the issue. Voltage (level) might be a little bit of issue, but it’ll probably only be like 9-10db hotter than a relatively hot guitar signal, and keyboards (and interfaces) usually have ways to adjust their output volume. Then ground loops, which really are best dealt with in other ways, but sure a transformer is a convenient way to not have to think about that. In short, yeah you’ll be fine. Pedal away. |
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Post by geo on Aug 4, 2023 11:05:34 GMT -5
as a word of caution, i would start with the piano output volume on the low side and bring it up until it's loud enough but before distorting the sound. line level for audio gear generally means an output of 1 V. guitar pickups are generally on the order of a couple hundred milliVolts so effects designed for a guitar level input might distort on the input stage when used with a line level input, so best practice is to bring the source (ie piano) volume up slowly that being said you won't break anything so have at it Thank you!! I knew the impedance would be an issue, so anything like a fuzz pedal might not behave very nicely, but I wasn't sure if the voltages would be out of line. Thank you to everyone for suggestions on how to wire it all up for the best sound, least hum, etc! |
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Post by ashcatlt on Aug 4, 2023 11:48:57 GMT -5
I mean, you could put a lowpass in front of the fuzz pedal and get most of the way there. Might be your keyboard has one built in?
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Post by geo on Aug 5, 2023 3:16:53 GMT -5
I mean, you could put a lowpass in front of the fuzz pedal and get most of the way there. Might be your keyboard has one built in? A low pass filter in front of the fuzz? What's the idea? |
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Post by ashcatlt on Aug 5, 2023 9:06:21 GMT -5
When you plug a passive guitar into a classic fuzz with its low inZ, it forms an LPF with the inductance of the pickup and that’s most of what separates fuzz from distortion. When the source is not inductive, that doesn’t happen naturally, so the fuzz is just distortion. Put a filter in between, now it’s a fuzz again.
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Post by geo on Aug 5, 2023 11:04:55 GMT -5
When you plug a passive guitar into a classic fuzz with its low inZ, it forms an LPF with the inductance of the pickup and that’s most of what separates fuzz from distortion. When the source is not inductive, that doesn’t happen naturally, so the fuzz is just distortion. Put a filter in between, now it’s a fuzz again. Ohhh wow!! That's so cool. Thanks! |
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Post by ashcatlt on Aug 5, 2023 13:45:36 GMT -5
Oh yeah. If you’re playing a guitar into a distortion pedal without that natural loading, you can just turn down the guitar’s T pot and get that fuzzy fun.
Now, I did say “most of the way there”. Fuzz boxes do a thing when you roll down the V pot of a guitar. People will say that it “cleans up nicely”. I think at least part of what makes that work is that the V pot puts some series resistance between the pickup and the low inZ at the fuzz, partially isolating the inductance and basically shelving that high frequency energy back up. So it’s a little brighter going into the fuzz when you turn down a little bit. You can’t really get that from a static LPF, but if you’re just going for stoner metal or those singing fuzz leads that go all ring-mod-ish when you play double stops and stuff, just cut the treble before any distortion and you’re there.
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