Help micing combo amp.....clipping...

[d0zerz]

I'm recording a Deluxe reverb (22W combo) with a sm57 into an audiobuddy.

 

Cranked the DR is fairly loud...and the audiobuddy's just got that one gain knob, and even when I have it as low as it'll go without being off, I still get bad clipping bringing it into cubase. I'm new to the amp miking thing...been using modellers or just recording acoustic/vocals where volume isn't an issue.

 

 

...should I just keep moving the mic back from the speaker or do I need a new preamp? I though moving the mic away from the speaker compromized the tone in some way

 

Any suggestions would be much appreciated

 

P.S. ...the 57 doesn't require phantom power right? ...is there any harm in providing it power anyway?

[Paully]

The cheapest way is to back the mic up. Otherwise you might try the next cheapest.. a mic line attenuator. ProCo makes them in 10, 20 and 30dB models.

 

http://www.procosound.com/kwikfixers.htm

 

Phantom shouldn't hurt your mic. If worried, contact Shure 'to be sure'!

 

Paul

[Danny (NS::U)]

I wonder if the outputs of the AudioBuddy are referenced to +4 dBu. If you're passing a really hot signal, and then connecting to -10 dBV equipment (regular soundcards and the like), then that might be part of the problem.

 

You might be able to keep your mic placement and amp level by using one of those inline attenuators, or you could try to see if there is a way to attenuate the input levels of whatever happens to be the audio interface. Failing all of that, you can indeed pull the mic a bit farther from the cabinet, which doesn't necessarily mean disaster (though it will change things, of course)

[the stranger]

That seems odd, I would wonder if Danny's comments are on base.

 

In all my years of miking guitar cabs, I haven't ever experienced a situation of having too much gain coming from a dynamic.

[Danny (NS::U)]

He cold also be plugged into a "mic" input, now that I think about it. It wouldn't be the first time that I've heard of it, especially if it isn't labeled clearly.

[where02190]

Originally posted by d0zerz I'm recording a Deluxe reverb (22W combo) with a sm57 into an audiobuddy.

 

OK and then what is the Audiobuddy plugged into?

 

I'm guessing an AD input that is either set to the wrong sensitivity or is a mic not line level input.

 

We need more info on your setup.

[d0zerz]

Yeah sorry guys, I should have specified what it's going into.

 

It's going into the line-in of my soundcard & I'm using cubase (that shouldn't matter though right?)

 

The levels are good with the amp on about 3 ...when it gets to 4 it's loud clean and 5 it's subtly breaking up (the amp that is...) the signal starts clipping at the amp around 4....I've got the mic placed pretty close to the speaker.

 

...what are the consequences of moving it back more? Do I lose high end? I know when I record acoustic stuff from farther it often ends up sounding thin and distant....

[MrKnobs]

That's THE classic audiobuddy problem. It's not the computer card, it's the Audiobuddy. There's no fix other than back the mike up, as the clipping is happening in the Audiobuddy.

 

Terry D.

[where02190]

It's going into the line-in of my soundcard.

 

As in cheezy stock computer sound card with 1/8" trs connections?

 

Sounds to me like you are plugging in a +4 output from your audio buddy into a -10 input on your cheesey sound card.

 

There's nothing wrong with your Audiobuddy, you're overloading the input to your soundcard.

 

You can either get a +4/-10 converter like this one from Ebtech, or get a better ADDA interface with +4 i/o, like this one from M-Audio.

[d0zerz]

Originally posted by where02190 As in cheezy stock computer sound card with 1/8" trs connections? Sounds to me like you are plugging in a +4 output from your audio buddy into a -10 input on your cheesey sound card. There's nothing wrong with your Audiobuddy, you're overloading the input to your soundcard.

 

Yes it's a cheezy 1/8" line-in from my 5 year old sound blaster using the kx drivers for latency. I suppose I could adjust the input in the kxcontrols..... (why didn't I think of that first?)

 

Thanks for all the comments guys. One question: I never really understood relative decibel ratings. Is 0db a standard signal strength? So +4 out on the audiobuddy would imply that it's giving a 4db boost to '0db'?

 

...and -10 means it's 'expecting' a 10db weaker signal?

 

I also have an ART tube MP which I don't get this problem with because I can turn it down enough (it's got a +20db switch that you can turn off) ...but I find the audiobuddy sounds better for acoustic/voice so I wanted to use it to mic this amp....

[d0zerz]

Originally posted by MrKnobs That's THE classic audiobuddy problem. It's not the computer card, it's the Audiobuddy. There's no fix other than back the mike up, as the clipping is happening in the Audiobuddy. Terry D.

 

I suspect you might be right, because it has those 'near clipping' indicator lights...and it seems they're always on with the mic close.....

[where02190]

+4/-10 refers to input sensitivity. Consumer devices, like home stereos, your sound card, etc, have a -10dbV sensitivity, whereas pro gear will either be switchable or be +4dbu. the difference between the two is about 11db, pretty significant. If your preamp, which you're already running pretty hot, has a +4 output, and you plug it into that -10 soundcard, it's going to overload the inputs of the soundcard, redline your software meters, and drive into digital clipping at the converters.

[MrKnobs]

Originally posted by d0zerz I suspect you might be right, because it has those 'near clipping' indicator lights...and it seems they're always on with the mic close.....

 

There have been like 1,000 posts on AudioBuddy clipping over the years on this forum and others. It's a well known problem.

 

However, if you're lucky, it could be what Where is saying instead. Be sure you're plugged into the line input of your sound card rather than the mic input, of course.

 

And open up your soundcard control software. If you're lucky, there might be some colored meters to look at. If so you can see the clipping if it's happening at the computer input.

 

If not, just connect the Audio Buddy output to something else you have handy (like a power amp, guitar amp line input, etc) and listen for the clipping.

 

Best of all, invest in a slightly better soundcard or external sound device for your computer. MAudio makes some decent ones, and they will improve your sound considerably over most stock computer sound cards or onboard chipsets.

 

Terry D.

[where02190]

Be sure you're plugged into the line input of your sound card rather than the mic input, of course.

 

Consumer audio card line inputs are typically -10dbV, the output of the Audiobuddy is +4dbu. Consumer sound cards cannot handle +4dbu levels, they will overload and distort.

[d0zerz]

Originally posted by MrKnobs Best of all, invest in a slightly better soundcard or external sound device for your computer. MAudio makes some decent ones, and they will improve your sound considerably over most stock computer sound cards or onboard chipsets. Terry D.

 

Can you elaborate on this? I've thought about getting one of those cheaper maudio 4 or 8 input cards that'll do 24bit recording, but I wondered what the point was...I figured...I only really need 2 inputs and input's an input and shouldn't color the sound at all

 

Is the only difference the 16 vs 24bit? Is the sound quality that noticeable?

[Danny (NS::U)]

Any A/D converter is going to color the sound, though some are prized because (like any other piece of gear) they either color the sound in a way that someone likes, or color the sound unnoticably.

 

Recording at 24 bits pushes the distortion due to quantization error (inaccuracy in converting very quiet parts of signals) down to lower signal levels. The better representation of low level details may not seem like a big deal, especially with loud guitar, but I think it's worth preserving as much good information as possible for as long as possible when recording (digital or analog).

[where02190]

and input's an input

 

Do a search on +4dbu vs -10dbV, and you'll learn quickly this is absolutely false.

[d0zerz]

Originally posted by where02190 Do a search on +4dbu vs -10dbV, and you'll learn quickly this is absolutely false.

 

I assumed so given terry's comment & the subsequent conversation about their implications on signal strength. ...but what about in terms of the subjective sound 'quality'?

 

I tried googling those terms, but it's not very nice with numbers and units (dbu...)

 

All I found was this:

 

You may have heard that professional gear is

[Paully]

Originally posted by d0zerz I tried googling those terms, but it's not very nice with numbers and units (dbu...)

 

The clinical definition is:

 

0 dBu Preferred informal abbreviation for the official dB (0.775 V); a voltage reference point equal to 0.775 Vrms. [This reference originally was labeled dBv (lower-case) but was too often confused with dBV (upper-case), so it was changed to dBu (for unterminated).]

 

Or less formally(and incorrectly), could mean 'unbalanced'.

 

Paul

[Danny (NS::U)]

A big reason for preferring +4 dBu as a reference, rather than -10 dBV, is because it usually implies that the +4 device can handle a larger voltage swing (across the board - inputs and outputs). Larger voltage swings mean that the signal can get higher above the noise floor, which translates into signals with more clarity and less low level "grunge."

 

According to http://www.sengpielaudio.com/calculator-db-volt.htm

+4 dBu = +1.78 dBV. The voltage difference between +4 dBu and -10 dBV nominal levels, then, is nearly 12 dB. I would be very happy to get 12 dB farther away from whatever noise floor I happen to have, when practicable.

 

In general (and assuming that you don't have a defective or shoddy piece of gear), more ability to handle voltage swing = better potential for handling audio. (Although, again, this is assuming that all other quality factors are equal. There are some "consumer" audio products which can probably beat the pants off of some "pro" products.)

[where02190]

Or less formally(and incorrectly), could mean 'unbalanced'.

 

Not necessarily. Many pro units that are balanced i/o also have switchable sensitivity, but switching the sensitivity doesn't change the balanced circuit to unbalanced.

[d0zerz]

Originally posted by Paully The clinical definition is: 0 dBu Preferred informal abbreviation for the official dB (0.775 V); a voltage reference point equal to 0.775 Vrms. [This reference originally was labeled dBv (lower-case) but was too often confused with dBV (upper-case), so it was changed to dBu (for unterminated).] Or less formally(and incorrectly), could mean 'unbalanced'. Paul

 

Thanks....

 

 

....unfortunately as a non-technical person (when it comes to audio & electronics) this doesn't help me a whole lot, I'm more looking for 'high level' descriptions of the differences, in terms of the subjective 'measures'.

 

this quote in particular stood out to me:

 

That + 4dBu is somehow inherently

[Paully]

Originally posted by d0zerz ....I'm just trying to determine if it's worth it for me to upgrade my sound card to cheaper 'professional' gear like the m-audio audiophile 2496

 

If that's the case, you should be asking about the quality of the AD converters that these things use. IMHO, hooking them up right is something you should study a little bit first. I have a little M-Audio 410 that I've used for a while, and it sounds just fine. They're under $300 now. Upgrading your card will probably make you a very happy camper. As for the 'V vs. u' issue, it makes little difference to me as I know what they mean. I just thought you needed a definition, and the one I posted is part of Rane's definitions. Good luck with your search.

 

Paul

[where02190]

Any upgrade is going to be better than a stock computer soundcard that is -10dbV sensitivity. At least you won't be overloading the input to the converters with your preamps +4dbu output level.

[MrKnobs]

Originally posted by d0zerz Can you elaborate on this? I've thought about getting one of those cheaper maudio 4 or 8 input cards that'll do 24bit recording, but I wondered what the point was...I figured...I only really need 2 inputs and input's an input and shouldn't color the sound at all Is the only difference the 16 vs 24bit? Is the sound quality that noticeable?

 

Several things to discuss.

 

I don't own an AudioBuddy and have never used one, so I accepted Where's comments as correct and set about educating myself on the Audio Buddy. To my surprise, after spending about an hour on the manufacturer's and other websites, there was no definitive statement in the technical specs or manual indictating whether the AB operates at -10 or +4 dB.

 

Worse, I couldn't even tell if the level control is a pad on the input or controls the output level. About the only thing I could conclude is that the Audio Buddy is very poorly documented.

 

Regarding the computer sound card issue:

 

As others have said, the quality of cheap A/D converters varies quite a bit. Noise is especially an issue. At work I have a $5000 Larson Davis A/D converter, a $200 Echo Indigo PMCIA converter for use in a laptop, and of course the sound chipset that came in my desktop computer.

 

The noise floor on the desktop's sound device is absolutely horrible compared even to the Indigo card. Part of that, no doubt, is because the inside of a computer is an extremely noisy electrical environment to design for.

 

Nevertheless, MAudio's 2496 is very good quality for the price (I have this card in a machine at home), which was under $100 last time I checked. Not only do you get the better quality converters, you get 24 bit depth and up to 96kHz sample rate, and some modest software with the package. I don't use the little version of Cakewalk or whatever came with it, but I do appreciate the card's onboard mixer software and display. If you had that, for example, you wouldn't be asking us where the overload is happening, you could look at all the pretty colored VU meters.

 

To me 96k isn't all that important, but 24 bit is great. 24 bits lets you be a little less apprehensive about your recording levels, lets you mix quiet sounds with really loud sounds without any problem, lets you track vocals and bass with no compression and compress later without worrying about too few bits in the quieter passages, and just plain sounds better - not a subtle difference at all.

 

Another thing that the MAudio card gives you is a SPDIF input. If you ever get an outboard preamp or reverb or some other device that has a digital output, you'll be able to go straight in via SPDIF with bit accurate results. Bit accurate means the digital file the 2496 records from it's digital input will be exactly the same as the digital output the preamp sent.

 

Regarding -10dB vs +4dB: This is just not a big deal from your perspective. The only thing that makes it a big deal in this case (if indeed this is what your problem is) is that you have a signal mismatch between the output of your AudioBuddy and the input of your computer soundcard.

 

You don't need anything expensive to fix this problem. You just need an attenuator cord or a couple of 50 cent resistors soldered together as a voltage divider. Last time I checked, Radio Shack sold a cable with a resistance attenuator inside it, or you can easily make your own with the two resistors, or possibly even one.

 

Terry D.