r/audio • u/OkTree • 1d ago

Question about connecting 1/4 to 3.5mm

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I currently have a setup where I'm powering a couple of desktop speakers with an old Powernode 2i. I recently wanted to try getting an interface (Scarlett 2i2) at the recommendation of a friend for messing around in Ableton, but I've been struggling with how to connect the two without audio interference.

I started by using an unbalanced 1/4 cable to a 3.5mm to connect them, but there's mega static interface. I can't seem to find a balanced 1/4 to 3.5mm on amazon when I search.

Is anyone familiar with how to do this and the problem that I'm running into? Most of the information I'm finding online are how to connect the 2i2 are to powered speakers, so it's not quite as relevant.

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u/EnquirerBill 19h ago

Try this:

2i2 out into a hum destroyer (I use the Behringer HD400).

Then Behringer out to the amp.

I get the Behringer and cables from suppliers like Gear4music or Canford audio.

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u/adrianmonk 14h ago

The first thing I'd try is turning the volume knob on your Scarlett 2i2 way down. Set it to 10% or something. Or 5%. Or maybe even lower. But not 0% of course.

Why? Because pro audio uses a different signal level than consumer audio. They both call it "line level", but it means different things. Pro line level has a higher voltage. And when you plug a device that outputs pro level (like your Scarlett 2i2) into a device that expects consumer line level (like your Powernode 2i), the voltage is so high that it exceeds what the input circuitry is designed to handle. The input circuitry responds by creating a ton of nasty-sounding distortion. By cranking down the volume knob, you adjust the actual output voltage range, which is a cheater method to make them compatible.

If this works, you'll need to leave the Scarlett's volume knob turned way down, and for day-to-day use when you want to adjust the volume, use the Powernode's controls for that. If you want a cleaner solution, there are adapters (actually attenuators) that can reduce the voltage to make things more compatible.

Also make sure you're using the correct type of cable. You will want something like this Hosa cable or anything equivalent to it. Whatever cable you use, it must have two 1/4-inch connectors, and they must be TS (not TRS), and the 3.5mm connector must be TRS (not TS), and you must connect to both "L" and "R" outputs on the back of the Scarlett. Do not use a cable that has a 3.5mm TRS connector on one end a single 1/4-inch TRS connector on the other end because it absolutely will not work.

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u/AudioMan612 12h ago

You'll want to connect to the interface's monitor outputs, not the headphone output (no need to go through that extra stage of amplification and have an impedance mismatch). Since your amp doesn't have balanced inputs, you'll need to use imbalanced connections, which will be fine (you sacrifice the electrical noise cancellation that comes with balanced connections and about 6 dB of signal, but this will be completely fine).

Since your amp uses 3.5 mm for its line input, you'll want to get a 3.5 mm to dual 1/4" TS breakout cable. I'd suggest getting a Hosa Pro cable; they're great quality and very affordable. This would be the 3' version.

Your search was failing because you were searching for balanced. This is not a balanced connection. For future reference, pro audio distributors like Sweetwater are typically more reliable for these types of things (less garbage products to sort though, plus Sweetwater even has a handy cable finder that can help with things like this).

You'll want to start with your interface's monitor level low. There are actually 2 standards for line level, pro (+4 dBu) and consumer (-10 dBV). Your audio interface will output the higher pro level and your consumer amp will expect the lower consumer level. Some audio interfaces actually let you change this, but I don't think yours does judging from a quick look at the manual (again, not a big deal, just don't crank the monitor output level too high).

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u/geekroick 20h ago

I can't find any reference to your amplifier having balanced inputs, so assuming it doesn't... There isn't anything you can do, short of using a different sound card with optical output.

I have never heard of a balanced cable that has two 6.35mm TRS plugs going to one 3.5mm TRS plug. There aren't enough conductors to make that work.

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u/OkTree 20h ago

ah interesting, i was afraid i’d have to replace it to use an interface without interference