Recording Heavy Guitars; Crackling Noise

[Axemaster G]

I'm trying to record distorted electric guitar with a condenser mic and cab. The problem I'm having is that the sound seems to "tear up" with a sort of crackling sound, particularly on sustained notes/chords. I was wondering whether this may be due to an inappropriate load presented by the preamp... Any thoughts?

 

[TalismanRich]

I have no clue what you mean by an "inappropriate load presented by the preamp". If you are referring to having too hot of a signal going to the preamp, then that's possible. How loud is the amp? Most mics can easily handle around 120dB or more. If there's a 10 or 20dB pad, it can go even higher. Now, if you are blasting the mic and have the preamp input too high, you're probably clipping the signal. It should show up on the interface. In that case, a simple turn of the input level should fix it.

If your input is going into the DAW too hot, it will show up as clipping, which is very easy to see in the waveform, and sounds like crap, often as a crackling sound.

What interface and mic are you using? How loud is your amp?

The other possiblity is that the mic is simply picking up sounds that you aren't hearing in the room.

 

[Axemaster G]

I have no clue what you mean by an "inappropriate load presented by the preamp". If you are referring to having too hot of a signal going to the preamp, then that's possible. How loud is the amp? Most mics can easily handle around 120dB or more. If there's a 10 or 20dB pad, it can go even higher. Now, if you are blasting the mic and have the preamp input too high, you're probably clipping the signal. It should show up on the interface. In that case, a simple turn of the input level should fix it.

If your input is going into the DAW too hot, it will show up as clipping, which is very easy to see in the waveform, and sounds like crap, often as a crackling sound.

What interface and mic are you using? How loud is your amp?

The other possiblity is that the mic is simply picking up sounds that you aren't hearing in the room.

My signal chain is as follows: Bugera 6262i > Iso Cab w/ V30 speaker > SM27 > ART TPS II Pre. I intend to record to digital too but I've determined the issue as being at the Mic/Preamp stage. I have the pad engaged on the mic and I'm told that the mic can handle high SPL's, so I'm ruling that out. That, plus the observation I made about the issue being less audible when I up the impedance. I guess I'm wondering whether a better pre would handle the situation better; I notice some of the more modern 500 series preamp designs have a high impedance at the mic input (anywhere from 7-15k Ohms), could this be a better solution for my needs?

 

[TalismanRich]

I seriously doubt that a different preamp will change things. Loading mostly seems to affect dynamic mics. Typical inputs are around 2K with most preamps. Your TPS goes from 150 to 3K, so that's fine.

The SM27 is supposed to handle 150+dB with the pad enabled, which is beyond jet engine territory, so that shouldn't be an issue unless you are running things at full song in the small ISO cab. I don't know what the V30 can put out for a max level up close. It's rated at 100dB but sensitivity is usually measured at 1 meter.

If you are recording, where does the signal go after the TPSII? If you are feeding a mic input, you easily overdrive things. Mic inputs take millivolts of level, line inputs are typically closer to one volt. The TPS supposedly can put out over 10 to >12V on the output. You need to feed a line input and also keep levels appropriate.

Maybe if you can post a short (1 min or so) MP3 of the problem we might be able to better understand what you're hearing.

 

[ecc83]

A'hem! So you are running a 120 watt valve head into a 60 watt rated speaker? Now I know V30s are tough but not that tough! Are you sure it is not just the speaker complaining?

At its rated power the V30 will produce around 118dB but in closed box and close up the mic will experience a much higher sound level, still, that mic with pad engaged should handle it (unless perhaps phantom power is low?)
It would be interesting to hang a DVmeter (which y'all should have!) across the mic and see w'appen?

But, I am pretty sure it is the preamp that is being overloaded. Why are you using a capacitor mic? They don't usually sound good on guitar speakers. Easy check would be to swap it for a dynamic. Even then you might get too hot a signal.

Dave.

 

[Axemaster G]

I seriously doubt that a different preamp will change things. Loading mostly seems to affect dynamic mics. Typical inputs are around 2K with most preamps. Your TPS goes from 150 to 3K, so that's fine.

The SM27 is supposed to handle 150+dB with the pad enabled, which is beyond jet engine territory, so that shouldn't be an issue unless you are running things at full song in the small ISO cab. I don't know what the V30 can put out for a max level up close. It's rated at 100dB but sensitivity is usually measured at 1 meter.

If you are recording, where does the signal go after the TPSII? If you are feeding a mic input, you easily overdrive things. Mic inputs take millivolts of level, line inputs are typically closer to one volt. The TPS supposedly can put out over 10 to >12V on the output. You need to feed a line input and also keep levels appropriate.

Maybe if you can post a short (1 min or so) MP3 of the problem we might be able to better understand what you're hearing.

I guess it'll be going to the balanced line in on my interface. I've got a mixer that I've been using to monitor from and dial in the tone and that's how I've been listening to it. I'll try and upload a clip next time I get the chance.

A'hem! So you are running a 120 watt valve head into a 60 watt rated speaker? Now I know V30s are tough but not that tough! Are you sure it is not just the speaker complaining?

At its rated power the V30 will produce around 118dB but in closed box and close up the mic will experience a much higher sound level, still, that mic with pad engaged should handle it (unless perhaps phantom power is low?)
It would be interesting to hang a DVmeter (which y'all should have!) across the mic and see w'appen?

But, I am pretty sure it is the preamp that is being overloaded. Why are you using a capacitor mic? They don't usually sound good on guitar speakers. Easy check would be to swap it for a dynamic. Even then you might get too hot a signal.

Dave.

You know, I swapped the speaker that was already in it for a V30 I had just to see the difference and told myself I'll keep the volume fairly low for this purpose. I've since completely forgotten all about it, whoops! Thanks for reminding me, I might put the old one back in now! Having said that, this issue was present on the speaker that was in it before, so don't think it's that that's causing the problem. As for the mic, I suppose I'm looking for a full-range and detailed sound which is why I went for a condenser. I'll try with a dynamic and see if the issue persists. I'm sure I'm not using too much gain at the preamp, if that's what you mean...

 

[ecc83]

I guess it'll be going to the balanced line in on my interface. I've got a mixer that I've been using to monitor from and dial in the tone and that's how I've been listening to it. I'll try and upload a clip next time I get the chance.



You know, I swapped the speaker that was already in it for a V30 I had just to see the difference and told myself I'll keep the volume fairly low for this purpose. I've since completely forgotten all about it, whoops! Thanks for reminding me, I might put the old one back in now! Having said that, this issue was present on the speaker that was in it before, so don't think it's that that's causing the problem. As for the mic, I suppose I'm looking for a full-range and detailed sound which is why I went for a condenser. I'll try with a dynamic and see if the issue persists. I'm sure I'm not using too much gain at the preamp, if that's what you mean...

What was the original speaker? There are few guitar speakers that can handle 120W despite what some makers might claim. Then that head could easily push 150W if you really gave it the beans.

I would not think you would need ANY gain on the pre amp! Even at minimum that cap' mic might overload it.

Dynamic mics will pick up all the frequencies you can get out of a guitar speaker and even then you will need some 'fizz' correction.

Dave.

 

[Axemaster G]

What was the original speaker? There are few guitar speakers that can handle 120W despite what some makers might claim. Then that head could easily push 150W if you really gave it the beans.

I would not think you would need ANY gain on the pre amp! Even at minimum that cap' mic might overload it.

Dynamic mics will pick up all the frequencies you can get out of a guitar speaker and even then you will need some 'fizz' correction.

Dave.

I'm not exactly sure what the original speaker is. It's an Eminence 16 Ohm custom made for the cab (a Jet City one). It's rated at 100W which I thought would be okay so long as I didn't crank the amp all the way up. I've used a load box/speaker sim type thing with my amp in the past which has an LED meter which indicates how much power is going through it. With this as a reference, I don't think I'm getting near to 150W at the volume I have the amp set to.

 

[Ujn Hunter]

Do you hear the crackling from the speakers? Or is it just in the Mic/Recorded signal? Are your pickups too close to the strings?

 

[jimmys69]

Upload a clip for sure.

Do you have a 57 sitting around? I have never had any luck with heavy guitars and condenser mics. 421, 57, and maybe a ribbon for room sound. Never a LDC. The frequency range of a high gain amped guitar just doesn't need the sensitivity of a condenser mic.

 

[ecc83]

I'm not exactly sure what the original speaker is. It's an Eminence 16 Ohm custom made for the cab (a Jet City one). It's rated at 100W which I thought would be okay so long as I didn't crank the amp all the way up. I've used a load box/speaker sim type thing with my amp in the past which has an LED meter which indicates how much power is going through it. With this as a reference, I don't think I'm getting near to 150W at the volume I have the amp set to.

Well, the thing is, the point of using an iso-cab (or indeed a load box) is to allow the amplifier to run at its tonal "sweet spot" but without endangering windows, ears or social harmony. Now, contrary to common thought, you don't need to blow the guts off a valve amp but with 120 watts of 6L6 you are going to have to hit it pretty hard.

However, I still think the most likely thing overloading is that mic pre amp.

Dave.

 

[Axemaster G]

Upload a clip for sure.

Do you have a 57 sitting around? I have never had any luck with heavy guitars and condenser mics. 421, 57, and maybe a ribbon for room sound. Never a LDC. The frequency range of a high gain amped guitar just doesn't need the sensitivity of a condenser mic.

I do have a 57 as luck would have it. I know it's the obvious choice for heavy guitars, I suppose I was just trying to do something... not obvious. The room with all my gear in it is like a sauna at the moment (experiencing a heat wave where I am), can't really function in those conditions but I upload a clip once I can muster it!

Well, the thing is, the point of using an iso-cab (or indeed a load box) is to allow the amplifier to run at its tonal "sweet spot" but without endangering windows, ears or social harmony. Now, contrary to common thought, you don't need to blow the guts off a valve amp but with 120 watts of 6L6 you are going to have to hit it pretty hard.

However, I still think the most likely thing overloading is that mic pre amp.

Dave.

From my experience with my iso cab the louder it gets the less defined the tone gets; it puts me in mind of the hearing loss you experience with the changing pressure on an aeroplane. I'm constantly trying to strike a balance of finding a level where there's clarity without it sounding thin and weak due to the volume being too low. But I should definitely be using a less powerful amp! Hoping to find a 50W head that'll fit the bill...

 

[Gtoboy]

A

I do have a 57 as luck would have it. I know it's the obvious choice for heavy guitars, I suppose I was just trying to do something... not obvious. The room with all my gear in it is like a sauna at the moment (experiencing a heat wave where I am), can't really function in those conditions but I upload a clip once I can muster it!



From my experience with my iso cab the louder it gets the less defined the tone gets; it puts me in mind of the hearing loss you experience with the changing pressure on an aeroplane. I'm constantly trying to strike a balance of finding a level where there's clarity without it sounding thin and weak due to the volume being too low. But I should definitely be using a less powerful amp! Hoping to find a 50W head that'll fit the bill...

A condenser mic is great for getting the sound of the amp "in the room" including reflections, et al. For iso type mic'ing, a dynamic close to the grille, or a ribbon 10-15 " from the speaker both work great. Crackling like you have described sounds like possible cable and/or connection issues. I would start with contact cleaner and hit every connection. Also the older the mixer, the more likely the pots/sliders may have contact conditions that could cause noise so work those babies to clean em up.

 

[rayc]

HEAVY guitars aren't THAT heavy when recorded. Pull the gain & level back - if you DAW signal sounds messed up it probably too much of everything all at once. Record a second track as close to the original as you can.
hard panned double guitar gives heft, heaviosity and tone.

 

[Axemaster G]

Thanks for your suggestions. I've got a couple of recordings that I did with a condenser for your listening displeasure. There's loads of noise that's audible in the sustained chords. That noise is coming from my amp, it's present when I'm not playing anything. If I turn my amp off or switch to the clean channel it's silent. I think my amp needs looking at, sometimes I can hear a shrill overtone that sounds like rushing air- could it be the tubes or something like that? You can hear the crackling and tearing up sound (a separate issue) slightly on the sustained chords too. I have to say it was worse before! Finding it hard to determine whether this sound is coming from my amp or whether it's the recording. Oh, and I recorded the second of the two because I was experimenting with balanced/unbalanced connections. I'll try with a 57 and see if it's improved.

Sound 1

Sound 2

 

[ecc83]

I have had a listen to both your clips friend and I really cannot find much to fault them for. Now I freely admit that my ears are pretty ***t these days but I had the tracks cranked on cans and ran a RTA spectrum on part of the second clip* to be honest, the clips sound just as good (or bad!) as dozens I have heard over the years alongside over driven amps in the workshop ranging from 5watts of valve to 200 watts.

The fact is, to me OD valve sound does not bear close scrutiny. It is SUPPOSED to be loud and a bit 'noisy' and yes, even the odd crackle!

*I could not get a handle on the amp noise. I need 10 secs of 'mayhem' then hand damp the strings for another 20.
Preff attached as a 320k clip as that saves me having to record it to stuff it in the RTA.

Dave.

 

[Axemaster G]

I have had a listen to both your clips friend and I really cannot find much to fault them for. Now I freely admit that my ears are pretty ***t these days but I had the tracks cranked on cans and ran a RTA spectrum on part of the second clip* to be honest, the clips sound just as good (or bad!) as dozens I have heard over the years alongside over driven amps in the workshop ranging from 5watts of valve to 200 watts.

The fact is, to me OD valve sound does not bear close scrutiny. It is SUPPOSED to be loud and a bit 'noisy' and yes, even the odd crackle!

*I could not get a handle on the amp noise. I need 10 secs of 'mayhem' then hand damp the strings for another 20.
Preff attached as a 320k clip as that saves me having to record it to stuff it in the RTA.

Dave.

Well thanks Dave, that's good new I suppose! I appreciate the feedback 'cause I'm not always sure whether I've got things right at the recording stage. Having an ear for these things comes with experience I guess.

I didn't really capture any of the amp noise on it's own. Any that was there I foolishly edited out (not helpful!). It's just a constant hiss, I think as the chords quieten down it starts to surface. Must contribute to the overall noise floor somewhat. Anyway, not the worst thing in the world, there seems to be a few videos online on the subject of hissing amps I'm just struggling to find the time to fix it at the moment.

 

[ecc83]

Well thanks Dave, that's good new I suppose! I appreciate the feedback 'cause I'm not always sure whether I've got things right at the recording stage. Having an ear for these things comes with experience I guess.

I didn't really capture any of the amp noise on it's own. Any that was there I foolishly edited out (not helpful!). It's just a constant hiss, I think as the chords quieten down it starts to surface. Must contribute to the overall noise floor somewhat. Anyway, not the worst thing in the world, there seems to be a few videos online on the subject of hissing amps I'm just struggling to find the time to fix it at the moment.

You might not be able to improve it much. 100W valve amps are inherently noisy beasts unless very carefully designed.
I don't know that amp but hiss is most likely the first stage valve, almost always a 12AX7, if not a pre amp valve, could be an anode load resistor. They are usually 100k Ohms and some mnfctrs still fit Carbon composition types. Metal Film is much quieter.

But to be quite honest you will struggle to get such amp another 6dB quieter.

Dave.

 

[TalismanRich]

I just gave the two samples a listen, and even with headphones, I find it difficult to tell what you might be thinking is crackling vs just the pure distortion from the guitar amp itself. As for the background noise, any time I turn up the drive to get that type of sound, such as on my Marshall DSL, it automatically gets a lot more noise. That's because you are driving the gain so high that any noise from either the guitar's pickup or the first preamp stage is multiplied.

I looked at the first file, and it doesn't appear to have any flat topped peaks, and the max peak was about -6dB, so it doesn't appear that you have any clipping going on. However, if you look at the waveform of the sustained part of IsoCab1, you can see a spike in the wave. I'm guessing it's part of the original signal, not something introduced by the recordings, since it's identical on every wave for a long period of time (~2 seconds). Maybe this is what you are hearing.

 

[rob aylestone]

I'm with the others - if I'd recorded that, nothing would have me experimenting with balanced vs unbalanced or messing around. That sounds like I would expect it to sound - the decay and change in tone as the strings ring out and decay sounds exactly like it should. I have no idea what you are hearing and finding 'a fault' - it's not something I can detect as wrong.