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Amp to PC - Strange problem
Old 30th December 2010
  #1
Gear Nut
 
Misaria's Avatar
 

Amp to PC - Strange problem

New here, 2nd post, so I hope I'm in the right place!

I used to have a Peavy Rage 15w and a Crate GX-15, both are small guitar combos.
I wanted to use the distortion from the headphones-output on the combos with IR's, since I was tired of digital distortion and couldn't afford any gear..

I tried using the Peavy (HP-output>Line in), but the sound disappeared and I knew something wasn't right..
So I used it in combination with a cheap mic tube-pre.. and the pre suddenly faded and stopped working.. So.. I'm guessing the Peavy sends out electricity.. The pre still works.. it just stopped working at the time..
Tried it with a DI, didn't work either..

Then I tried with the Crate, headphones-output..
And it worked.. It worked well, I liked some of the sound I got from it..
So I tried using the Peavy through the Crate.. and it also worked..

Btw, the peavy works fine with headphones..
So does the Crate..

The experimenting was done with an M-Audio Delta Audiophile 24/96..
Like I said, the Crate worked fine, for long sessions.. the Peavy killed the equipment within 10 minutes or less..

I decided to remove the cab and speaker and make "heads" of them, to save space.. So I chopped them up.. I read that it could be done since they're solidstate..
And I got a new soundcard, an M-Audio 1010LT..
Now..
I can't get sound from the Crate into the soundcard..
Works with headphones.. But not with the line in.. as it did with the 24/96..
I re-connected the speaker, but no sound to the soundcard..

I don't get it..
What is the problem? Any solutions?
I have better stuff now, but I would still like to use them..

I have a cheap mixer, and a DI that can channel electricity..
I haven't tried connecting Amp>DI>Mixer>PC, nor Amp>Pedal>PC..
Maybe it's bad ideas..

I'd also like to know if I can connect the "heads" to a new combo I'll be getting this week, a Warwick Blue Cab 60.1, or is that also a bad idea? :D

Thanks!
/Mikael
Old 4th January 2011
  #2
Lives for gear
 

you need to isolate the peavy's output. a slight negative voltage is applying to the input causing the preamp to bias off.

a good start with this is putting an .47 uf cap inline with the + signal and a 1k resistor in shunt after the cap ( across the computer input).


head---cap--|----pc input
''''''''''''''''''' 1k
''''''''''''''''''' |
''''''''''''''''' gnd
Old 23rd March 2011
  #3
Gear Nut
 
Misaria's Avatar
 

Quote:
Originally Posted by drtechno View Post
you need to isolate the peavy's output. a slight negative voltage is applying to the input causing the preamp to bias off.

a good start with this is putting an .47 uf cap inline with the + signal and a 1k resistor in shunt after the cap ( across the computer input).


head---cap--|----pc input
''''''''''''''''''' 1k
''''''''''''''''''' |
''''''''''''''''' gnd
Thanks for the answer Drtechno.. and sorry for the late reply..
I didn't want to answer this late, but if I can't use the amps, I guess I'll throw'em away..

Since I didn't want to "necrobump" this I posted in another forum (swedish) and asked them, I copied what you wrote, drtechno.

Basically they told me to apply a resistor in the chain, so I've ordered the different ones they recommended to try. and I'll make a little box with the resistor to be placed between Headphone-output and before the amplifier,,

Still haven't tried using them with my bassamp, that has both passive and active inputs, as well as line-in..

So, will a resistor or two in the chain work?
I'm guessing the load from the headphones output is to great for the line-in on my soundcard (although it wasn't before with the cheaper one of the same brand)
Old 24th March 2011
  #4
Gear Nut
 
Misaria's Avatar
 

Anyone? Bueller? JP22?

Today I got the parts I need (if I understood it right) to make the little box to have between the amps headphones output and the soundcard's line-in..
But I'm not sure exactly how to read drtechno's connecting..
If you think you know, do tell!
Old 25th March 2011
  #5
Gear Nut
 
Misaria's Avatar
 

http://i.imgur.com/bEowL.jpg

That's how interpret drtechno's reply.. And I guess that's what I'm gonna try..
But I have no idea if that's the right way of doing it.. :S
If you know your stuff, tell me if it's wrong..
Old 26th March 2011
  #6
Lives for gear
 

yep.
p.s. if the sound is too thin, up the capacitance (1 uf or even 2.2 uf).
Old 27th March 2011
  #7
Gear Nut
 
Misaria's Avatar
 

Quote:
Originally Posted by drtechno View Post
yep.
p.s. if the sound is too thin, up the capacitance (1 uf or even 2.2 uf).
Thanks for the reply, unfortunatly, it didn't work.
Here's what I did: http://i.imgur.com/02w03.jpg

The resistor: 4.7 ohm.
The cap: MKS2 470nF 63v

It's the only cap I have atm..
But I still have 4.7 ohm resistors left and some 4.7 kohm and 10 kohm..

I only tried it with my Crate.. no sound.. but the recording channel reacted to switching the amp on and off..

What do now?
Old 27th March 2011
  #8
Lives for gear
 

4.7 ohm is like a short in line level world.

here are 2 examples of ac coupling without transformers.


also make sure you are using a headphone plug (trs) from tip to sleeve when plugging into headphone jack on amp. 1/4 inch standard guitar cable does not work here.
Attached Thumbnails
Amp to PC - Strange problem-coupling.jpg  
Old 28th March 2011
  #9
Gear Nut
 
Misaria's Avatar
 

Quote:
Originally Posted by drtechno View Post
4.7 ohm is like a short in line level world.

here are 2 examples of ac coupling without transformers.


also make sure you are using a headphone plug (trs) from tip to sleeve when plugging into headphone jack on amp. 1/4 inch standard guitar cable does not work here.
T..R..S..
The Dr saves another patient..
That was the solution.. so far.. with the Crate..
Do I feel stupid..

I had a couple of TRS cables that I had no use for (the soundcard is pre-owned and I got extra cables).
The TRS splits into two RCA named TIP and RING.. both worked and sounded the same..

I didn't have time to check it with the box I built (the pic I last posted)..
But I will try it tomorrow..
I guess it's not good for the soundcard to recieve from a headphone out?
I never had a problem with it before, but maybe that was just dumb luck..
So using the box would be preferable I guess..

AND.. I hope it works with the Peavey aswell..
If not I can channel it through my Crate.. it has worked in the past..

"4.7 ohm is like a short in line level world"
I didn't understand that.. the diagram you showed me says 4.7 k_ maybe that's short for Ohm.. or it means I need to switch the resistor in the box to a 4.7 Kohm I have extra.. :O

Yet again, thanks for the replies!
Old 5th April 2011
  #10
Gear Nut
 
Misaria's Avatar
 

Quote:
Originally Posted by drtechno View Post
yep.
p.s. if the sound is too thin, up the capacitance (1 uf or even 2.2 uf).
Maybe I have to do that.. Not sure..
Still haven't tried, the box I built, with the Peavey.. Still have some fear I'll fry something..

But I tried it with the Crate..
Direct to line-in = Very noisy, but what I was used too with the Crate.
Through the box (Signal>In/Out>Line-in) = Very thin, noisy and sounded pretty crap.
Through the box (but the other way around, Signal>Out/In>Line-in) = Sounds good, but I've checked the schematic and.. yeah.. the signal goes the wrong way.. :S
But this way sounds the best hands down...
Wonder why that is.. :O
Old 8th April 2011
  #11
Lives for gear
 

impedence. remember. you are going from low Z to high Z. you might want to try headphone + to pin 2 of xlr mic pre and headphone - to pin 3 of xlr on a mic pre.
Old 8th April 2011
  #12
Gear Nut
 
Misaria's Avatar
 

Quote:
Originally Posted by drtechno View Post
impedence. remember. you are going from low Z to high Z. you might want to try headphone + to pin 2 of xlr mic pre and headphone - to pin 3 of xlr on a mic pre.
I'll try that.. I have a XLR to RCA-converter.. I could use that, if I wire it right.. Or I'll get a XLR-plug..

Should I use this with the box, or without?
Since the headphone output is 4Ohm.. the crate seems to work fine despite that.. but the peavy sends electricity I guess..

I've tried it before with my preamp.. but.. the preamp died for a minute..
But that was just with a simple guitar cable.. not wired to XLR as you suggested.. I'll try it!
Old 12th April 2011
  #13
Lives for gear
 

solder direct.


To quote by one of my laws in electronics, you can go from low-z to high-z as long as the voltage level does not over drive the input.


direct line level rca to xrl line cable:
Make sure phantom power is off our you might damage the component that is connected to the RCA Jacks (if there is ground loops present).

rca tip wire is solder to pin 2 xlr
rca sleeve to pin 3 xlr
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