Noise removal from amp to computer

Matt Till · #1 10-25-2004, 09:18 PM

Hi...

I run my Crate amp out of the headphone jack to my line in. The amp is clean, the cables are clean, but a bunch of noise ends up on my track. I can remove the noise, but it takes a bit of tone out. Why am i getting this noise? Is it preventable?

Ray Salamon · #2 10-25-2004, 09:34 PM

Quote:

Originally Posted by Matt Till

Hi...

I run my Crate amp out of the headphone jack to my line in. The amp is clean, the cables are clean, but a bunch of noise ends up on my track. I can remove the noise, but it takes a bit of tone out. Why am i getting this noise? Is it preventable?

My guess: it's the line in. Try plugging your bass straight into it (buy the $2.50 1/4" mono -> 1/8" stereo jack at Radio Shack) and see what results you get.

Ray

Matt Till · #3 10-25-2004, 10:31 PM

OH I mean the line in instead of the microphone. I get a little noise with the just bass, but it also gets zero tone.

Ray Salamon · #4 10-25-2004, 10:35 PM

Eh, I don't follow...show me your signal chain like this:

Bass->FX->amp->output (which ever it is?) -> input (which ever it is?) -> program used even.

Ray

Matt Till · #5 10-25-2004, 10:43 PM

Sorry
Bass->FX->amp->computer->Cool Edit Pro

Ray Salamon · #6 10-25-2004, 10:48 PM

What ouput do you use on the amp (headphone is what I thought originally), and to what input on the computer (line in, or mic in?). Also, try getting Cakewalk for recording. I don't know much about software for recording, but I know that if it's not doing it's job right, it could be the source of much headache.

Ray

Matt Till · #7 10-25-2004, 10:59 PM

headphone, yes.

The input is the line in, but noise is created in the mic input as well.

Ray Salamon · #8 10-25-2004, 11:01 PM

Quote:

Originally Posted by Matt Till

headphone, yes.

The input is the line in, but noise is created in the mic input as well.

Could be sound card, but I doubt it. How did you test your cables? Can you plug your bass straight into the sound card and record, and see if you get the same result?

Ray

Matt Till · #9 10-25-2004, 11:07 PM

I'm thinking it might be the headphone output is noisey. Because it isn't near as bad when I record from my amp. It's just the amp gives everything such a full tone.

Ray Salamon · #10 10-25-2004, 11:09 PM

If it's the headphone output, which would also be my guess, I'd say get the $0.50 part and replace it (a no sweat fix really). Try just plugging headphones in and see what the results are. What you hear then is what the computer'll record.

Ray

Matt Till · #11 10-25-2004, 11:27 PM

Thanks.

Ray Salamon · #12 10-25-2004, 11:29 PM

Try the headphones thing first, as it may save you some trouble...

Ray

cmhgreg · #13 10-27-2004, 07:13 PM

This might be too simple, but you might have a ground loop problem, especially if you have a bunch of things plugged into one circuit. If you have equipment that has three prong plugs (no doubt you do), try plugging them into one of those three prong to two prong adapters. You might not want to run it through one of these all the time, but it might help you isolate the problem. I just had this problem running a mic feed from an old Traynoe mic mixer/amp into another mixer. When I disconnected the feed from the Traynor mixer/amp the hum would go away. I put the adapter on the power cord for the Traynor and bingo, the hum was gone.

Matt Till · #14 10-27-2004, 08:53 PM

Wow... I never thought of that but it's very likely, I'll give that a shot!!

Big Benner · #15 10-30-2004, 04:30 PM

I've had similar problems when the different units are plugged into different wall outlets. Solution was to by a power bar and plug everything in. Hopefully you won't blow the wall/house fuse.

How does the headphone output sound with good quality headphones (really listen, and play something and then stop without touching any controls and hands off the bass)?

I use the headphone output on my Boss ME-50B straight into the Line In on the sound card and everything works fine with Cubase.

nonsqtr · #16 10-30-2004, 05:09 PM

Nah, not a ground loop. That would be "hum" instead of "noise". Noise means the hissy and crackly type sounds, and hum is hum. Are we agreed on this terminology?

Then, the acid test for the noise level of an amp's output is to use that same output with different sinks. For example, if you plug in your headphones and they sound nice and quiet, but you plug that same output into your computer and it's noisy, then there is an electronic issue in your sound card.

Most of the time, noisy inputs equate with cheap components. That would be especially true with cheap sound cards. A Sound Blaster, for example, uses the world's cheapest components. That's why you can get one for next to nothing. Generally speaking, the more expensive sound cards use more expensive resistors (and other components), thereby reducing the noise level.

The other possibility is that you could be experiencing a massive impedance mismatch. Unfortunately, it's going in the right direction. In other words, amp outputs are typically low impedance, and if you use that to feed a high impedance load (like a sound card, which is typically on the order of 10k for the line input), you're going low->high, which is okay. If on the other hand, you try plugging your passive bass (typically 20k ohms or more) into the low-impedance mic input of the sound card (typically 600 ohms or so), you're going high->low, which could definitely explain the loss of tone.

Can you quote any specs from your sound card? What kind is it, and what are the input impedances for the mic and line inputs?

pdusen · #17 11-03-2004, 08:32 PM

You're all reading too far into this. I've done this before. The problem is the soundcard.

Line In jacks are built to take in the pre-amplified signal of desktop microphones, and the signal gets "amplified" when it is brought into the system. When you send the already-amplified signal from the headphone jack to the sound card, it re-amplifies it and pulls dozens of other sounds into play, as well as simulating an overdrive effect. (This happend when I tried to record my guitar this way; it sounded overdriven, even though I played it on the clean channel.)

Doubtless the signal can't take the amount of drive its being given, and that's where your noise is coming from.

Passinwind · #18 11-03-2004, 08:56 PM

Quote:

Originally Posted by pdusen

Doubtless the signal can't take the amount of drive its being given, and that's where your noise is coming from.

Yep, but that's not the soundcard's fault. Go to Radio Shack and buy an attenuator cable. Plug your headphone out into it, and life will be way mo bettah.

Those attenuators come in different strengths, a 20 or even 30 dB pad works well for most situations like this. I've encountered this many times when someone wants to run a walkman headphone output into the mixing board for between set tunes, for example. Not all headphone outs are created equal though, some sound fine unattenuated.

nonsqtr · #19 11-03-2004, 11:05 PM

Quote:

Originally Posted by Passinwind

Yep, but that's not the soundcard's fault. Go to Radio Shack and buy an attenuator cable. Plug your headphone out into it, and life will be way mo bettah.

Those attenuators come in different strengths, a 20 or even 30 dB pad works well for most situations like this. I've encountered this many times when someone wants to run a walkman headphone output into the mixing board for between set tunes, for example. Not all headphone outs are created equal though, some sound fine unattenuated.

Yet another version of noise!

I'd still like to know which "noise" we're talking about.

Passinwind · #20 11-03-2004, 11:24 PM

Quote:

Originally Posted by nonsqtr

I'd still like to know which "noise" we're talking about.

Me too, but I figured I might as well inject another permutation on general principles.