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Connecting amp to notebook

notivago

notivago

Guest
Dec 23, 2011
19
4
50
Montreal, QC, Canada
#1
Hi there people,

Thanks in advance for your time and help. I am dabbling with home recording and I would like some advice on the matter.

I have being using amplitube with:
- iRig: The first one. It sucks on the low end, I guessed it was due to lack processing power. So:
- iRig Stomp: With a power cord and an iPad and a little learning I managed to extract a decent sound from the bass, it did not fixed my playing though. =)

But recently I started to explore my amp, an Heartke A70 and found out that it has a balanced XLR out, it made me want to plug it on my notebook and try out something different like Ardour but I don't know how to proceed, how do I connect a balanced line level output to a notebook?

Preferably in a way that sounds at least as good as the rig set up.

As I understand it, the amp does the same an DI would do, right? Do I need an interface? I was a little afraid that if I get an interface it would burn as the interface instrument/mic expect low powered instrument input, right?

And how about a mixing table like Behringer XENYX502 would it add value or is it a waste of resource?

Thanks
 
#2
You won't burn out the line in on the laptop as long as you don't use the speaker out from the amp.

You don't need anything else. The quality of the analog parts in the internal soundcard might be bad and the A/D converter might be bad. If it is bad a mixer won't help (*). If it is good then you are all set.

To be sure to be able to recover from accidents (especially mechanical ones, breaking out the plug) it might be safer to use a USB soundcard. That would also be a solution if the sound quality on the line is isn't good enough.


(*) the situation is different if you have mic level, not line level. Even if the laptop has a mic in it almost certainly has bad enough quality that you either want some audio gear to boost mic to line level (probably also required for phantom power) or a USB soundcard with a real microphone preamp.
 
#6
It works.
It's rare to find a laptop that doesn't have high quality audio built in.
Sometimes the Mic in and Line in are the same jack - either it prompts when you plug into it or you have to adjust the input type in the control panel.

Since the "line in" is stereo you can get two connectors Y
CYX405F.jpg


If you need ASIO for the DAW software ASIO4ALL works great.
 
#8
First attempt: failed.

I went to a local store. They told me there was no such a thing as xlr to 1/8 cable, I told them I saw it at amazon, the guy said he meant around here. I asked for an xlr to USB, again there is no such thing, again I saw it at amazon.... He told me to look at the cable store right beside, I went in, the guy told me that balanced xlr to 1/8 trs was a myth but he would craft me the cable unbalanced...

I got the cable, plugged it to amp, to the note, set the line as per support site, run garage band, config for built in line input, channel 1, 2, stereo.... None worked. Tried to plug it to iPhone with amplitube, nothing at all.

Both gave me completely dead input. I am guessing the cable is Boggus.
 
#9
notivago said:
First attempt: failed.

I went to a local store. They told me there was no such a thing as xlr to 1/8 cable, I told them I saw it at amazon, the guy said he meant around here. I asked for an xlr to USB, again there is no such thing, again I saw it at amazon.... He told me to look at the cable store right beside, I went in, the guy told me that balanced xlr to 1/8 trs was a myth but he would craft me the cable unbalanced...

I got the cable, plugged it to amp, to the note, set the line as per support site, run garage band, config for built in line input, channel 1, 2, stereo.... None worked. Tried to plug it to iPhone with amplitube, nothing at all.

Both gave me completely dead input. I am guessing the cable is Boggus.
Click to expand...

The cable must not(!) be symmetric. That's probably the guy's confusion.

The XLR needs to be put one hot to ground and the other one to the plug (either just tip or both tip and ring). But you can't put one hot on the tip and the other one on the ring, which would be symmetric.
 
#10
An XLR to mini TRS is balanced.
Your input on a laptop is not, it's stereo.
The plug may fit the jack and they are both 3 conductors, but the electronic circuit is different.

The XLR out on an amp is sending 2 mono signals that's positive on pin 2 and negative on pin 3. Pin 1 is shield/ground. Your laptop is looking for 2 signals of the same polarity.

So for simplicity lets say the amplitude/volume of the signal in the XLR cable is a value of 5.

If input in the laptop was a balanced like on a mixer or interface , it receives pin 2/tip of TRS plug as +5, and receives pin 3/ring of TRS as -5 then inverts the polarity from -5 to +5, then sums the 2 identical signals into 1.

Because its not a balanced input it sums +5 with -5.
What happens when you add +5 and -5.......
You get 0.
 
#11
Hi people,

I opened the cable to see how it was wired and what I found was that pins 1 and 3 were soldered together and routed to TRS ground and 2 was soldered to two wires going both to tip and ring.

As far as I understood this is according to what uOpt told it should be, and that would not fall into the problem uhordinator described.

I guess either the cable is broken somewhere or I am setting something wrong.
 

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