Guitar amp headphone output and audio interface

[Ray Stevens]

I have a Squier SP-10 practice amp and a Behringer UMC202 HD

audio interface. I am listening to a guitar piece in Transcribe, trying

to learn it. I need to use headphones. I need to try to connect the

headphone out on the amp (if possible) to the usb audio interface

input so I can listen to the amp and Transcribe on my PC through

the audio interface at the same time. If I try to connect a guitar cable

from the amp headphone output to the audio interface input and

listen to the output from the headphone output on the audio interface

there is very, very little volume. Is there some way to make the

volume louder. I know that there is some kind of a connection

because if I turn the volume to max on the amp and I can barely

hear the sound from the guitar through the audio interface

headphone jack. My video/audio clip of the guitar lesson handled by

Transcribe is loud and clear

 

[Gtoboy]

The headphone output is a dual unbalanced TRS plug but the input of your interface thinks you have a balanced TRS plugged in. You will need to get a splitter that takes the headphone output and splits it into two TS mono plugs then either one or both will be recognized by your interface as an unbalanced instrument input which should give you better volume.

 

[Ray Stevens]

The headphone output is a dual unbalanced TRS plug but the input of your interface thinks you have a balanced TRS plugged in. You will need to get a splitter that takes the headphone output and splits it into two TS mono plugs then either one or both will be recognized by your interface as an unbalanced instrument input which should give you better volume.

Thank you. .

 

[keith.rogers]

[MENTION=199787]Ray Stevens[/MENTION], you didn't say what interface you are using, but the 1/4" input jacks usually take both instrument or line level input, which is selected with a switch. The jacks can handle an unbalanced input, though are designed to accept and use a balanced one.

I'd probably just use a converter plug like this to convert the headphone output to mono (if you have a 1/8" aka 3.5mm cable), since you don't really need the stereo signal.
Amazon.com: Monoprice Metal 6.35mm (1/4 Inch) Mono Plug to 3.5mm Stereo Jack Adaptor - Gold Plated: Home Audio & Theater

Or a converter cable if you don't already have a cable. Not sure how you're getting there now.
Amazon.com: Hosa CMP-105 1/4 inch TS to 3.5 mm TRS Mono Interconnect Cable, 5 feet: Musical Instruments

The low level is likely caused because the preamp is getting a stereo signal in a conductor that should essentially be providing nothing but the "balance". Normally a headphone output is on par with a line level signal, and not a guitar.

 

[mjbphotos]

Just plug your guitar directly into the Behr interface, switching the input to 'inst'. Make sure the 'pad' button is not pressed in.

 

[Ray Stevens]

Just plug your guitar directly into the Behr interface, switching the input to 'inst'. Make sure the 'pad' button is not pressed in.

If I was using an amp sim like Amplitube I would plug the guitar into the interface. But since I want to use my amp and not a sim wouldn't what you suggest completely bypass the amp? What I'm trying to do is simultaneously listen to the amp and Transcribe on the PC in my earphones but the amp output through the amp headphone jack connected to the audio interface input is too weak. I guess what the amp puts out and what the interface takes in is just not compatible.

 

[ecc83]

Found a schematic for that amp. Hoped it had a line or FX out? No such luck.

Yes, the headphone output will put the same signal on both pins of the balanced input, net result zilch. As mentioned, you could get a 1/4" TRS (stereo) plug to two 1/4" TS (mono) plugs and feed that to the interface.
Another option is a jack splitter on the input to the Fender amp. Guitar in one input and then feed the split to the Instrument input on the Behringer.

Yet another option is a "DI" box. This takes the guitar signal and makes it suitable for the XLR mic input and virtually all DI boxes have a "slave" out to feed an amp as well. Google "Orchid Electronics"

Dave.

 

[keith.rogers]

If I was using an amp sim like Amplitube I would plug the guitar into the interface. But since I want to use my amp and not a sim wouldn't what you suggest completely bypass the amp? What I'm trying to do is simultaneously listen to the amp and Transcribe on the PC in my earphones but the amp output through the amp headphone jack connected to the audio interface input is too weak. I guess what the amp puts out and what the interface takes in is just not compatible.

As both [MENTION=89697]ecc83[/MENTION] and I tried to point out, plugging the stereo TRS plug into a jack expecting a balanced, mono signal is why the level sounds low. Convert the signal to mono and you'll be at a line level. Then you should monitor through the interface's headphone output just fine.

 

[Ray Stevens]

As both [MENTION=89697]ecc83[/MENTION] and I tried to point out, plugging the stereo TRS plug into a jack expecting a balanced, mono signal is why the level sounds low. Convert the signal to mono and you'll be at a line level. Then you should monitor through the interface's headphone output just fine.

Thanks guys for your replies. I understand now a little better what you gents are trying to tell me and what I have to do to get what I'm shooting for. You see what I want I was able to accomplish with my Mustang I amp which has an aux input. I just took the headphone out on the Behringer UMC202 HD audio interface (somebody else wanted to know what I am using) and plugged into the AUX in on the amp. However, the SP-10 amp is not as sophisticated. Therefore, not knowing dooodly squat about audio I thought I'd ask some experts. Thanks for helping.

 

[ashcat_lt]

Holy hell guys. A "guitar cable" is "mono" TS.

Plug it into a stereo TRS headphone output shorts the right side R connection to the sleeve. Any decent headphone circuit should be ok with that, and you'll have the left side audio on the T loud and clear.

Plug the other end into a TRS balanced input and that R is also shorted to the S. Any decent balanced input will be fine with that. The T still picks up the signal and should just work. We expect to lose about 6db because 1 -(-1) is twice as big 1-0, but it should still be a pretty decent level.

My first thought was also the L-R thing everybody's harping about, but then I actually read the OP.

That interface doesn't seem to have a input/computer monitor knob, but it will definitely require having the Direct Monitoring button engaged. If that doesn't help (or is already pressed), then there's something else going on.

 

[spantini]

...We expect to lose about 6db because 1 -(-1) is twice as big 1-0..

Algebra...!!??

 

[Ray Stevens]

Holy hell guys. A "guitar cable" is "mono" TS.

You just kick started my brain. This audio interface has two mic/inst -TRS/1/4" jack combo inputs. I have a standard guitar cable (mono) coming from the guitar amp headphone jack to the left side input on the audio interface. You can select either line or instrument with the control button. You just have to turn down the gain when set to inst. Either way, no sound in headset. So, based on what you said, I pulled the plug halfway out of the amp and I got sound out of the left side of the headset. The direct monitor button has to be depressed. I now wonder what would happen if I put a cable with stereo plugs into the interface and amp. Be patient guys my audio knowledge is negligible, which is not an overstatement

 

[mjbphotos]

If I was using an amp sim like Amplitube I would plug the guitar into the interface. But since I want to use my amp and not a sim wouldn't what you suggest completely bypass the amp? What I'm trying to do is simultaneously listen to the amp and Transcribe on the PC in my earphones but the amp output through the amp headphone jack connected to the audio interface input is too weak. I guess what the amp puts out and what the interface takes in is just not compatible.

You're just transcribing, so what difference is it what your guitar tone is like?

 

[Ray Stevens]

You're just transcribing, so what difference is it what your guitar tone is like?

Actually, I'm not transcribing at all. I'm learning somebody else's transcription. And the quest for just the right tone is the holy grail for a guitar player. The program "Transcribe" I use as a slow downer so I can watch the guitarists hands, strings played and notes sounded. Listening and watching at full speed I miss a lot of detail

 

[Ray Stevens]

The solution all along

The headphone output is a dual unbalanced TRS plug but the input of your interface thinks you have a balanced TRS plugged in. You will need to get a splitter that takes the headphone output and splits it into two TS mono plugs then either one or both will be recognized by your interface as an unbalanced instrument input which should give you better volume.

Globoy. Yours was the answer all along. I just didn't understand it. I found a page which shows a picture of exactly what you described. Obviously you know how this stuff works. Thank you.

 

[ashcat_lt]

So when you said "guitar cable" you actually meant TRS balanced cable? You use those for guitar regularly?

 

[Ray Stevens]

So when you said "guitar cable" you actually meant TRS balanced cable? You use those for guitar regularly?

No, under normal circumstances a mono cable is what I use between the guitar and amp. I was trying different cables in an attempt to get sound in my headphone simultaneously from the amp, the audio interface and the PC. I was informed by somebody in this thread what I needed. I received the same advice from Behringer who also supplied a picture. What I need to use is fig. 3

 

[ashcat_lt]

Oh shit. The "stereo" output to the headphones isn't actually two separate output circuits, just a single (probably opamp) split by straight wire. Shorting the R also shorts the L. Makes sense, but kinda half-assed on the amp end.

 

[ecc83]

Oh shit. The "stereo" output to the headphones isn't actually two separate output circuits, just a single (probably opamp) split by straight wire. Shorting the R also shorts the L. Makes sense, but kinda half-assed on the amp end.

"Half-assed" indeed Ash'. What they SHOULD do is feed the OP amp through two equal resistors of about 220R+ so that shorting one does not collapse the signal. Still not best practice but an NE5532 with both sections paralleled can cope with that.

Dave.

 

[keith.rogers]

TRS to TS cable from headphone to DI to whatever works fine for my Roland MicroCube - used it in a pinch more than once when needed to go direct on a "silent stage" after dumping the big Line 6 floorboard. I guess not all amp's headphone out circuits are the same.