Using my Laptop as an Amp

[jeremylangford]

So without buying a pro audio interface, would the most professional way to send a guitar signal to a computer for recording with your guitar amp be to put a mic in front of your amp and use the "Mic In" input on your computer so that the signal goes straight to the soundcard?

And would the most professional way to use a computer for guitar amplification without an audio interface be to plug the guitar chord directly in the "Mic In" input on your computer for the same reason?

Or does using USB and Firewire with audio interfaces send the signal straight to the soundcard just like the "Mic In" and "Audio In" inputs? Also, does a USB or Firewire cable transfer your signal slower than an instrument cable?

[D2o]

Hi Jeremy,

Caveat: Nothing that I do musically should be considered "professional".

Cynical1 or Ashcatlt or someone with much more experience can give you a more detailed answer to your question, but I thought you might benefit from the experience of someone who simply "plug and play"s.

I have plugged a "Shadow Original" 2500E passive transducer on an acoustic guitar directly into the mic input, with good results.

I have not actually tried plugging my electric guitar directly into the computer mic input. However, I routinely plug a line from my amp's headphone jack directly into the mic input* (so that I can record my electric guitar signal, processed through an effects pedal connected to the amp).

* set your amp volume to 0 (zero) before plugging it into your mic input, and slowly bring the volume up to where you need it (probably just 1 or so).

I do not know if guitar signal from an amp's headphone jack to your mic input, at high volume, could damage your computer ... but I'm quite happy if neither of us ever finds out.

I have also plugged a Samson CO1U ("U" = USB) condenser mic directly into one of the computer's USB ports.

All of this has worked flawlessly for me, for years, with no complaints.

Just my 2¢

D2o

EDIT: all of this supposes that you are simply looking for a way to record guitar signal directly to your laptop, as opposed to literally using your laptop as an amp.

[cynical1]

I appreciate the kind words from D2o. To be honest, I am an old analog war horse and just recently began digital recording. I don't have the coin right now to do it right, but I manage to guerrilla the process well enough to be effective.

Most of it translates over pretty well, and after 6 months at it I'd never go back to analog again. That said, let me qualify that.

Initially I ran the bass into an old Bass Rockman, then into the Line In on the sound card. It never had enough signal to satisfy me. I did run the bass out of the headphone jack on the amp and into the Line In on the computer. It gave a stronger signal, but it was too sterile for my taste. (No computers or soundcards were injured during the course of this testing)

I dragged out an old AKG mic and cabled it into the Mic input on the sound card. This worked the best for me. I never liked running the bass directly into the board anyway, so I may still have some lingering prejudices on that one...

Right now I would love to have a digital interface for the bass and the mic. When funds are available I'll probably do more research and pick one up. The USB or Firewire devices do not touch your soundcard inputs. They will generally use ASIO drivers, so don't try this on an older computer as the results will be disappointing at best.

There is a discussion in the Live Sound and Recording section that deals with some of this already, so I'll just point you to Hardware suggestions for Recording Computer rather then re-hash it here.

For recording I use Audacity, only because my computer coughs up blood when running the more elaborate software. I export to a .wav file and then mix and process it.

If you're looking to use the computer as an effects processor and amp modeler the same rules apply as the ASIO drivers. Make sure there is enough horsepower under the hood.

You can run adapter cables, 1/8" to 1/4" and back to rig it to go from guitar to computer to amp. The DI would be a better way to go.

Ash is the guru on this stuff...I just Rube Goldberg it...

Hope this helps

Happy Trails

Cynical One

[D2o]

Rube Goldberg line from amp headphone jack to computer mic jack.

[newey]

No, that's much too easy for Rube Goldberg. The Rube goldberg method would be something like:

"How to play your guitar through your PC"

1) Guitarist puts Sony Records A&R phone number in his cell phone's speed dial.

2) Guitarist plays song, using his guitar through his amp.

3) Guitarist dials Sony Records on cell phone, holds phone up to speaker.

4) Sony Records A&R department is closed, guitarist's call goes to voicemail where it is recorded.

5) On the following Monday, Sony A&R exec listens to messages, hears guitarist's song. Exec pulls the song off the tape, emails it to Sony CD production plant in Guangzhou, China.

6) Sony issues CD of song, sends 100,000 copies of CD to Amazon.com.

7) Guitarist boots up his PC, logs into Amazon.com, purchases CD.

8) Amazon.com ships CD via Fedex to guitarist.

9) Guitarist receives package, inserts CD into his computer.

10) Guitarist hears his guitar through his PC.

Or something like that. And no pro audio interface required!

[ashcatlt]

Well, since my name was mentioned...

You'll probably never see anybody that calls himself a professional doing any of this. They'll use some $$$ boutique outboard mic pre and a $$$$$ A>D converter. That doesn't really help you (or me) though.

Mic>soundcard will work, but I'd rather not. The mic pre in your soundcard is engineered for things like VoIP and other applications where fidelity is not really a priority. Plus, it's right there encased with a whole host transmitters of EM noise. It also shares power with some fairly noisy components. All of this extra noise will be unavoidable, and will be amplified along with your desired mic signal.

Plus, the software controls for these things are usually pretty basic. It can sometimes be frustrating trying to dial it up to find the right levels.

Guitar>soundcard will work as well, but probably won't be acceptable. The input-Z of these things is far too low for a passive guitar. I actually just did this the other day (testing my power supply) and there was a definite loss of high frequency response. Plus, I think you'll find that the (lack of) headroom in this mic pre will make it almost impossible to get a good level without distortion.

Better would be to run the guitar into a good Hi-Z buffer of some sort. Most commercial effects pedals (non-True Bypass) will do this just fine, even in bypass mode. A compressor could help the headroom issue.

Headphone out>soundcard will work as well. You'd be hard pressed to actually hurt anything this way. It might sound like things are falling apart, but there shouldn't be any permanent damage. Newer amps nowadays are including some form of speaker emulation on the headphone and/or line outs. Older amps without this will probably come through pretty harsh and nasty in the high end. You'd be surprised at how much high frequencies information those speakers roll off.

My head is spinning right now from a bit of over-indulgence last night, and the house is full of chattering children. I'll try and post something more coherent in a while.

[ChrisK]

I was looking into doing this as well, but didn't like what I read about the results. I wanted to capture signal with DC components as well, which is out of reach for this approach.

I bought one of these as it supports two high impedance (1 Meg Ohm) instrument channels that could possibly be used as a digital oscilloscope for audio. MF still has the Tapco Link.FireWire 4x6 Audio Interface for $99.99 (it just qualifies for free shipping).

This product includes Mackie's Tracktion Music Production Software.


If you want to use it with a laptop Firewire port, you'll need to get either a 4 pin to 6 pin adapter or a 4 pin to 6 pin cable.

MF has the Belkin cable for $20.
accessories.musiciansfriend.com/product/Belkin-4Pin-to-6Pin-Firewire-Cable?sku=580548

They're $11 at Amazon.com and they have free shipping.

They tend to be about $20 - 30+ in stores.