Line out distortion

TigerG · 12-23-2007, 05:35 PM

I have a couple amps I've been doing some recording with, using a line out taken off the signal going to the speaker. With both these amps, a strong attack on a note will result in ugly buzzy distortion, even with minimal gain and low output. The distortion is similar to the distortion you get when the input on the recorder gets overdriven, but the signal is well below the peak level, so the distortion isn't happening in the recorder. Last night as a test I recorded a guitar line, simultaneously micing the speaker onto one track and putting the line-out signal on another track. The speaker track is clean, while the line-out track has the distortion. Does anyone know how I might clean it up?

I know the easy answer here is to record off the speaker rather than the line out, but there are circumstances where I want to be able to record without using the speaker, and for most things I don't like the guitar-direct-into-the-board sound.

This schematic shows how the line out is set up:

http://www.tigergagan.com/images/sch...gpoweramp9.gif

Thanks to any and all who can help!

dai h. · 12-23-2007, 06:15 PM

you need a speaker simulating filter (EQ) on that line out signal otherwise it will sound buzzy

Chuck H · 12-23-2007, 07:37 PM

I've had good luck with speaker driven line outs without the need for a speaker simulator.

The impedance of your line out is probably too high for your board. Try swapping the 6.8kr with a 2.2k, change the 25k pot to 500 ohms and the 10kr to 10 ohms. Be sure to triple the wattage rating on the componants from the stock ratings.

HTH

Chuck

TigerG · 12-24-2007, 02:09 AM

Thanks guys. I'll try changing the line out first. But, if I need to go the speaker simulator route, is there a way to set up the filter, or should I look into buying a simulator?
Merry Christmas!

dai h. · 12-24-2007, 06:39 AM

you could do either depending on your resources, DIY skills, etc. I have a couple (Marshall SE100, Palmer PDI-03) and IMO they can be okay but a mic'ed real speaker sounds better to my ear even on someone's cheap camcorder recording.

Chuck H · 12-24-2007, 09:40 AM

Dai is right on. If you can do it, a mike on the speaker is best. I use a line out on my small amps for convenience. An 18 or 22 watt amp is only sometimes loud enough for small clubs. If I need a small volume boost I can use the line out conveniently without the need for a mike and no feedback issues. But most of the sound is still coming from my amp. I don't think I would rely on the line out by itself for good tone.

A neat trick I do is to run the line out to an A/B switch then to a channel on the PA. I dime my amp for the overdrive and when I turn down the guitar for clean tones (you have to have a "bright" cap on your guitars volume control for this) if I need a small volume boost I can step on the A/B switch and I'm good to go. Like having channel switching from a single channel amp.

Chuck

Paleo Pete · 12-24-2007, 02:33 PM

I agree too, I'll take a mic over a line in any day.

TigerG · 12-24-2007, 06:11 PM

Micing the speaker sounds best for sure, but sometimes circumstances, such as a girlfriend sleeping in the next room, require alternatives

Chuck H · 12-24-2007, 09:05 PM

"Micing the speaker sounds best for sure, but sometimes circumstances, such as a girlfriend sleeping in the next room, require alternatives"

Are you trying to use the line out without a speaker plugged in??? Or are you just playing the amp really, really low?

Chuck

TigerG · 12-25-2007, 04:13 PM

Speaker unplugged, but with a dummy load.

Bruce / Mission Amps · 12-25-2007, 05:13 PM

Quote:

Originally Posted by TigerG

Speaker unplugged, but with a dummy load.

Here's a little dummy load I've made up and have used.
The coils are just crossover inductors and the cap is a tiny 50v E-cap.
The last one I built used air coils and worked the same.
You can build one for under $10.00
Try it ... instead of a pure DC resistance for a dummy load.
It's not fabulous or rivaling a $150 gizmo but it seems to kill some of the harshness when recording using a parallel R divider line out from the OT secondary direct to a recorder or PA mixer, etc.
If you are using a big ass amp... of course up the values of the wattage rating for the inductors, resistors and use a 100v E cap.
I've used this one with Deluxe Reverb sized amp for years with no damage to any amp or the reactive dummy load.
I'm sure there are better ones but $ for $, this thing has been pretty good to me.

TigerG · 12-25-2007, 06:56 PM

Thanks Bruce. Any suggestions on a source for the inductors?

Bruce / Mission Amps · 12-25-2007, 10:03 PM

Quote:

Originally Posted by TigerG

Thanks Bruce. Any suggestions on a source for the inductors?

I bought some various air core inductors from www.PartsExpress.com a few years ago for around $3.50 each.
Just go there and put .22mH or .27mH or .33mH in the keyword window and something will probably pop up.

12-23-2007, 05:35 PM	#1
TigerG Member Join Date: Jul 2006 Location: Nashville, TN Posts: 29	Line out distortion I have a couple amps I've been doing some recording with, using a line out taken off the signal going to the speaker. With both these amps, a strong attack on a note will result in ugly buzzy distortion, even with minimal gain and low output. The distortion is similar to the distortion you get when the input on the recorder gets overdriven, but the signal is well below the peak level, so the distortion isn't happening in the recorder. Last night as a test I recorded a guitar line, simultaneously micing the speaker onto one track and putting the line-out signal on another track. The speaker track is clean, while the line-out track has the distortion. Does anyone know how I might clean it up? I know the easy answer here is to record off the speaker rather than the line out, but there are circumstances where I want to be able to record without using the speaker, and for most things I don't like the guitar-direct-into-the-board sound. This schematic shows how the line out is set up: http://www.tigergagan.com/images/sch...gpoweramp9.gif Thanks to any and all who can help!

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12-23-2007, 06:15 PM	#2
dai h. Senior Member Join Date: May 2006 Posts: 777	you need a speaker simulating filter (EQ) on that line out signal otherwise it will sound buzzy

12-23-2007, 07:37 PM	#3
Chuck H Old Timer Join Date: May 2007 Location: pacific north west Posts: 1,483	I've had good luck with speaker driven line outs without the need for a speaker simulator. The impedance of your line out is probably too high for your board. Try swapping the 6.8kr with a 2.2k, change the 25k pot to 500 ohms and the 10kr to 10 ohms. Be sure to triple the wattage rating on the componants from the stock ratings. HTH Chuck

12-24-2007, 02:09 AM	#4
TigerG Member Join Date: Jul 2006 Location: Nashville, TN Posts: 29	Thanks guys. I'll try changing the line out first. But, if I need to go the speaker simulator route, is there a way to set up the filter, or should I look into buying a simulator? Merry Christmas!

12-24-2007, 06:39 AM	#5
dai h. Senior Member Join Date: May 2006 Posts: 777	you could do either depending on your resources, DIY skills, etc. I have a couple (Marshall SE100, Palmer PDI-03) and IMO they can be okay but a mic'ed real speaker sounds better to my ear even on someone's cheap camcorder recording.

12-24-2007, 09:40 AM	#6
Chuck H Old Timer Join Date: May 2007 Location: pacific north west Posts: 1,483	Dai is right on. If you can do it, a mike on the speaker is best. I use a line out on my small amps for convenience. An 18 or 22 watt amp is only sometimes loud enough for small clubs. If I need a small volume boost I can use the line out conveniently without the need for a mike and no feedback issues. But most of the sound is still coming from my amp. I don't think I would rely on the line out by itself for good tone. A neat trick I do is to run the line out to an A/B switch then to a channel on the PA. I dime my amp for the overdrive and when I turn down the guitar for clean tones (you have to have a "bright" cap on your guitars volume control for this) if I need a small volume boost I can step on the A/B switch and I'm good to go. Like having channel switching from a single channel amp. Chuck

12-24-2007, 02:33 PM	#7
Paleo Pete Member Join Date: Oct 2007 Posts: 100	I agree too, I'll take a mic over a line in any day.

12-24-2007, 06:11 PM	#8
TigerG Member Join Date: Jul 2006 Location: Nashville, TN Posts: 29	Micing the speaker sounds best for sure, but sometimes circumstances, such as a girlfriend sleeping in the next room, require alternatives

12-24-2007, 09:05 PM	#9
Chuck H Old Timer Join Date: May 2007 Location: pacific north west Posts: 1,483	"Micing the speaker sounds best for sure, but sometimes circumstances, such as a girlfriend sleeping in the next room, require alternatives" Are you trying to use the line out without a speaker plugged in??? Or are you just playing the amp really, really low? Chuck

12-25-2007, 04:13 PM	#10
TigerG Member Join Date: Jul 2006 Location: Nashville, TN Posts: 29	Speaker unplugged, but with a dummy load.

12-25-2007, 06:56 PM	#12
TigerG Member Join Date: Jul 2006 Location: Nashville, TN Posts: 29	Thanks Bruce. Any suggestions on a source for the inductors?

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