Room sound out of guitar mixes

[NL5]

I don't think that's right about the phase thing. The out-of phase problem isn't directional; it's distance based. The sound waves have to hit the mics at exactly the right time where one is in a peak and the other is in a valley. A speaker is omnidirectional, so it doesn't matter if both mics are in front or in back, top or bottom, etc., or one one each. If they happen to be at the right distance where the mics pickup the soundwaves at the opposite end of the waveform, they'll be out of phase.

At least that's the way I've understood it.

But if I'm not mistaken (and believe me--I am mistaken a lot ) in this case it has to do with a push/pull issue (I'm sure there's a better term!). Since the speaker is actually moving back and forth, when you mic it front and back (as opposed to two in the front but at varying distances) one side's pulling air while the other is pushing.

This may be completely off base, but I believe it's the same logic behind flipping the phase on one mic if you mic the top and bottom of a snare. FWIW--I don't mic the back of my amp, but I do mic the top & bottom on snare, and flipping the phase on one works for me there.

It's a combination of direction and distance. If both mikes are the same distance from the speaker, but pointed toward/away from each other, then you'll probably want to flip the polarity on one of them because as the speaker pushes air toward one mike, it's pulling it away from the other (air isn't actually traveling, but that's another discussion). If the distances are different as well, then this throws every thing out of perspective because now the compression/rarefaction of air is reaching the mikes at different times. In this case, there will ALWAYS be phase cancellations and summations, so your task is to make them work with each other and sound pleasant. Inverting polarity may or may not help the sound.

Speakers are NOT omnidirectional.

As quoted above, different sides of the speaker will be operating as polarity reversed. If it was possible to get the mics perfectly in phase as well, and the speaker was omnidirectional, the resulting combination of the two mics would be a null. No sound. Of course, the sound radiating behind the speaker will only be the lower frequencies, so this is not possible in practice. Do you have to reverse the polarity? No. But 9 times out of 10, it's a much better starting point, and will in general, cause much less phase issues. Just as a note, when using two mics on one source, phase issues are impossible to eliminate. Especially when they are a spaced pair. You just have to try and optimize the phase relationship between the two mics.

 

[famous beagle]

Speakers are NOT omnidirectional.

As quoted above, different sides of the speaker will be operating as polarity reversed. If it was possible to get the mics perfectly in phase as well, and the speaker was omnidirectional, the resulting combination of the two mics would be a null. No sound. Of course, the sound radiating behind the speaker will only be the lower frequencies, so this is not possible in practice. Do you have to reverse the polarity? No. But 9 times out of 10, it's a much better starting point, and will in general, cause much less phase issues. Just as a note, when using two mics on one source, phase issues are impossible to eliminate. Especially when they are a spaced pair. You just have to try and optimize the phase relationship between the two mics.

Couldn't you judge nudge the tracks on your editor to have a perfectly "in-phase" pair of tracks?

 

[famous beagle]

Speakers are NOT omnidirectional.

As quoted above, different sides of the speaker will be operating as polarity reversed. If it was possible to get the mics perfectly in phase as well, and the speaker was omnidirectional, the resulting combination of the two mics would be a null. No sound. Of course, the sound radiating behind the speaker will only be the lower frequencies, so this is not possible in practice. Do you have to reverse the polarity? No. But 9 times out of 10, it's a much better starting point, and will in general, cause much less phase issues. Just as a note, when using two mics on one source, phase issues are impossible to eliminate. Especially when they are a spaced pair. You just have to try and optimize the phase relationship between the two mics.

And I didn't mean that speakers were omnidirectional the way a mic is omni. My point was that the sound coming out of them is, and it's going to reach the mic behind the amp at a different time than the one out front (granted, mostly bassy frequencies).

Even the sound that's being "pushed" out from the front of the speaker will travel backward (the bass frequencies) and hit the mic behind. Correct?

 

[NL5]

Even the sound that's being "pushed" out from the front of the speaker will travel backward (the bass frequencies) and hit the mic behind. Correct?

Yes, but at opposite polarity. just like the top and bottom of a drum.

 

[lpdeluxe]

If the previous suggestions don't work...

Untreated rooms frequently have bass buildup, and that's where a lot of the mud is.

Sometimes you can improve the room noise by running the track through a high-pass filter. Depending on the key the song is in (and whether you're using a 7-string or a baritone guitar) you can clean off the lower octaves where much of the annoying tubbiness resides.

Low E on a standard tuned guitar is 164.814 Hz; however, most players never get down to the low E so you can set the high pass at around 150 Hz and not lose anything. I'd suggest playing the track with the filter set to 150 Hz, then increase it until it stops sounding better (or starts sounding worse).

If your hardware or software doesn't allow this, use a mic that has a low filter incorporated: that's why they are on 'em!

You can't get rid of reverb: close micing or DI is the only answer for that. If you have a live room, try turning off the amp's reverb so it doesn't get muddier.

I usually record electric guitar direct (using an effects box to get the sound I want) so I bypass the whole difficulty...but I seldom record electric guitar these days. That's OK if you want a stomp-box sound, but a lot of players have a guitar/amp sound they depend on, and they are stuck with the acoustics and mics they have at hand.

 

[Hi_Flyer]

wow, what a trainwreck. prolly a fake account, but if not, here's my 2 cents...

1- there is little to no "room sound" in a close mic'ed guitar amp, so
2- get a real amp that actually sounds good and
3- forget about "better preamps"
4- it doesn't sound like you are ready for multiple mics yet, so use an SM57 or SM58 in front on the inner edge of the speaker cone. if it still sounds like crap, refer to #2

unscrew the ball off a SM58 and you got a SM57.

 

[WhiteStrat]

wow, what a trainwreck...

You're right--and I even participated in the train wreck. Thanks for bringing us back to basics.

One decent amp + one decent mic + a little time (should) = a decent guitar sound.

 

[thebigcheese]

I think we need a little more info on exactly what about the room you don't like. You said you like the sound of the guitar in the room, which says to me that you like the sound of the room, so... what are you trying to get rid of?

 

[IronFlippy]

Speakers are NOT omnidirectional.

As quoted above, different sides of the speaker will be operating as polarity reversed. If it was possible to get the mics perfectly in phase as well, and the speaker was omnidirectional, the resulting combination of the two mics would be a null. No sound. Of course, the sound radiating behind the speaker will only be the lower frequencies, so this is not possible in practice. Do you have to reverse the polarity? No. But 9 times out of 10, it's a much better starting point, and will in general, cause much less phase issues. Just as a note, when using two mics on one source, phase issues are impossible to eliminate. Especially when they are a spaced pair. You just have to try and optimize the phase relationship between the two mics.

Phase issues are impossible to eliminate with ONE mike if you're not in an anechoic chamber. Reflections off of the floor, walls, ceiling, among other reflective objects in the room interfere with the direct sound of the amp all the time, even when miking in extreme proximity. Hence, the room sound the OP is trying to eliminate will be impossible (realistically).

 

[NL5]

Phase issues are impossible to eliminate with ONE mike if you're not in an anechoic chamber. Reflections off of the floor, walls, ceiling, among other reflective objects in the room interfere with the direct sound of the amp all the time, even when miking in extreme proximity. Hence, the room sound the OP is trying to eliminate will be impossible (realistically).

True.

 

[rayc]

Stick it all in a wardrobe or cupboard, shut the door, play/record & if the result is the same it's your set up not the room.

 

[eyema_believer]

After much time and thought, I've decided that the only way to fix this problem is to do the ole "stand on your head while tracking your guitar" bit. First, you record your drums. Then, you record your guitar whilst standing on your head. Then, you re-track the guitar while standing on your head in a different room than where the amp is. After this, close your eyes, click your heels together, and say three times "there's no place like homerecording.com" and move along to recording the bass guitar, which you should do with a direct box, to get rid of the hum.

peese.

~Shawn

 

[mrface2112]

maybe the room isn't the problem here?

maybe the AMP is the problem? or the tone itself sucks?

if you're recording at a decent level, with a decent amp, using a decent mic with a decent mic preamp into a decent A/D converter (or decent tape)...........you should have ZERO problems with "room sound" in the mic.

take it back to the source. does the source suck?


cheers,
wade

 

[Light]

My suggestion, get rid of the second mic, stick a 57 down the speakers gullet, turn up your amp, and keep your signal chain after that as simple as possible. If it doesn't sound right, move the mic around a bit. It'll help. Avoid multiple mics whenever possible. If you need them, fine, but they will always add phase issues that just can't be fixed.


Light

"Cowards can never be moral."
M.K. Gandhi

 

[DrewPeterson7]

Low E on a standard tuned guitar is 164.814 Hz; however, most players never get down to the low E so you can set the high pass at around 150 Hz and not lose anything. I'd suggest playing the track with the filter set to 150 Hz, then increase it until it stops sounding better (or starts sounding worse).

Hmm. I just did a quick Google search, as I'd recalled low E being around 80hz-ish, and I've found a Yahoo Answers post agreeing with you, and then a whole bunch of guys saying it's about 82hz.

http://www.till.com/articles/PickupResponse/index.html

Figure 5 shows the frequency response on a log-log plot (log frequency and dB amplitude) of a neck position pickup as on a Stratocaster low E string (82 Hz open string, 25.5 inches scale, pickup located 6.375 inches from bridge).

Anyway, I've been told low B on a 7 is around 63hz or so, although it's also worth noting that since 9 times out of 10 the bass guitar will be playing the fundamental as one of its' overtimes, preserving your fundamental on a guitar isn't THAT crucial, and you can safely cut a bit above it without much damage. Take this with a grain of salt, of course, as I'm just your typical hobbyist bloke.

 

[lpdeluxe]

Hmm. I just did a quick Google search, as I'd recalled low E being around 80hz-ish, and I've found a Yahoo Answers post agreeing with you, and then a whole bunch of guys saying it's about 82hz.

Oops...too quick a perusal of my frequency chart: it's actually 82.407. =blush=

But my point is that the bottom end of the guitar isn't used that much, in most genres, so it's possible to scrape off the low end and still have the timbre you want. This is really a variation on the old Motown trick of carving out EQ domains for each instrument, but using filters rather than EQs (I know, that's an academic distinction, but in software there's a difference).

Low B would be 61.736 Hz...and, if you're down in that territory, there are a lot of other issues to deal with, such as the articulation of bass notes and whatnot. and you'd better have a treated room.

 

[Sloan]

What guitar and amp is being used here? What kind of sound are you going for?

 

[rayc]

I work, predominatly, with the low E & A on my 6 string semi acoustic Bruno(ah, you see I'm bassist by design but self accompanying guitarist by need - no one'll play with me - so my playing is rudimentary & BASSic). If I did any serious cutting I'd not have much but sympathetics, harmonics & accidents.

 

[lpdeluxe]

I work, predominatly, with the low E & A on my 6 string semi acoustic Bruno(ah, you see I'm bassist by design but self accompanying guitarist by need - no one'll play with me - so my playing is rudimentary & BASSic). If I did any serious cutting I'd not have much but sympathetics, harmonics & accidents.

Then I suggest you try a different strategy, if you are unable to come to terms with the room sound in your recordings.

 

[DrewPeterson7]

Low B would be 61.736 Hz...and, if you're down in that territory, there are a lot of other issues to deal with, such as the articulation of bass notes and whatnot. and you'd better have a treated room.

Eh, not that I'm tracking the greatest rhythm tones or anything I've ever heard, but it's less of an issue than you'd think. Just close-mic, and make sure you have a good bass tone to work with too. It just takes a bit of rethinking of the "purpose" of a guitar in a mix; when you're tuning that low, you just need to think about what the bass and kick are doing. I like to try to get the bass to cover most of the low end, leave the guitar pretty much alone in the midrange, and then use a brighter-than-normal kick with a lot of snap but a bit less low end body than normal to compliment the bass.

I still usually start a high pass around 60-90hz typically, anyway - the fundamental IMO is less important than the overtones for distorted guitar, provided you've got a solid bass sound.

It's when you get down into Meshuggagh territory that things get REALLY hairy, lol.