Tech: Adding line out to an amp

Subject: Tech: Adding line out to an amp
From: GUEST,Scorpio
Date: 28 Mar 09 - 05:38 AM

I have an excellent little acoustic amp (Behringer) but it has no way of connecting to a mixer. How difficult would it be to 'fix' this?

Subject: RE: Tech: Adding line out to an amp
From: Richard Bridge
Date: 28 Mar 09 - 05:59 AM

2 easy ways. A DI box with a link on the input side (but you lose the amp's colouration in the signal sent to the mixer), or a DI box with the necessary very high input impedance and ability to reduce the signal level attached to the speaker of the amp.

Subject: RE: Tech: Adding line out to an amp
From: treewind
Date: 28 Mar 09 - 06:02 AM

Are you sure you need to? As the speaker is part of the sound, you might well be better off miking the amp. A SM57 is good for this; experiment with position (pointing to side or centre of speaker, distance from speaker). Or a nice cheap Behringer C2, if your mixer has phantom power.

Breaking into the amp's electronics is fraught with unknowns. If you have to ask the question, you probably aren't competent (no offence intended) to do it... but if I needed to make such a mod, I'd try picking up a signal from the input to the master volume control potentiometer, assuming it's wired in the conventional way as a simple attenuator and not as part of a feedback loop.

I take no responsibility if you try this and something bad happens.

Anahata

Subject: RE: Tech: Adding line out to an amp
From: s&r
Date: 28 Mar 09 - 07:52 AM

Mic up the amp.

Stu

Subject: RE: Tech: Adding line out to an amp
From: mandotim
Date: 28 Mar 09 - 08:25 AM

50 or so on ebay gets you a Marshall AS50R; better amp, comes with effects, a balanced XLR input for a vocal microphone on the second channel, and more importantly a DI out. An old design, but nicely built and tough as old boots. I've swapped them loads of times for something I thought was better, but I keep coming back. If you must mike the amp, SM57s are good, but have a look at the Audix range as well. Thomann have some very cheap 'short' stands for microphones as well.
Tim

Subject: RE: Tech: Adding line out to an amp
From: GUEST,punkfolkrocker
Date: 28 Mar 09 - 09:01 AM

Online amp user groups usually have at least one regular 'tech expert' member
who claims to know just where to break the circuit between pre and power amps
to 'safely' insert a customized output/input FX send..

For example, I'm considering a reasonably tried and tested scematic diagram for modding my vox valvetronix amp
when the warranty expires in a few months time.
But it depends if I can find a reliable local amp electronics technician
and ££$$ the job would cost.

I'd suggest you look out for a good bargain used

http://www.award-session.com/ap10.html

That [or any other similar product available] would provide
all necessary extra signal routing & shaping options
without risking damage to your amp or electrecution..

Subject: RE: Tech: Adding line out to an amp
From: Richard Bridge
Date: 28 Mar 09 - 09:09 AM

Ebay is showing the Marshalls from £99 to £159 at the moment.

Subject: RE: Tech: Adding line out to an amp
From: wysiwyg
Date: 28 Mar 09 - 09:35 AM

Thanks to the posters who make it clear why one great blues band Hardi and I saw was mic-ing an amp. NOW it makes so much sense, and I would also know how to apply this advice in our situation.

~Susan

Subject: RE: Tech: Adding line out to an amp
From: pdq
Date: 28 Mar 09 - 11:22 AM

If you are going to add a jack for line-level output, he first thing you need is a circuit diagram for that exact amp model.

Study the diagram. The parts needed may be just 1 small capacitor, 1 resistor, 1 output jack and a short piece of shielded cable.

Subject: RE: Tech: Adding line out to an amp
From: mandotim
Date: 29 Mar 09 - 07:36 AM

Thanks Richard! I bought my last one a while ago, so I guess they've gone up. Still good value for a good,solid gigging amp with lots of useful features.
Tim

Subject: RE: Tech: Adding line out to an amp
From: GUEST,Scorpio
Date: 30 Mar 09 - 05:30 AM

Thanks for the help, guys.

Subject: RE: Tech: Adding line out to an amp
From: pdq
Date: 30 Mar 09 - 11:31 AM

If you provide a link to the proper circuit diagram, I will explain some of the options in detail.

I can't PM you since you are posting as a guest.