Posted by: worshipguitarguy | August 11, 2006

Isolating Guitar Amps

marshall_amp.jpgThe idea of isolating a guitar amp is one alot of professional guitarists follow.  But what’s the point of it?  (In other words, my amp looks really cool, so why should I hide it so no one can see it???)

To answer, I’ll start off by talking about how an amp works.  If you play through a good tube amp, you may know that you have two sections where volume affects your tone, the preamp and the power amp.  As you increase the volume going through the first section, the preamp, you create overdrive.  By increasing the master volume, (which controls your power amp) you increase the amount of volume coming out of the speaker.  But as you do this, pay attention to your tone, because it will also change as the volume goes up.  Most people would describe the sound as getting “warmer” or “fuller” as the volume increases.  Some of this is due to the increased power through the tubes, and some of it results from more volume going through the speaker(s).  Most guitarists agree that the more volume you run through your tube amp, the better your tone sounds.  (Note: volume also affects the speakers in solid state and modeling amps, but the change may not be as noticeable as with a tube amp.)   

But there is a catch.  To get that good tone, you have to run your amp pretty loud, which is not practical for those of us who play in small to medium sized rooms.  Many 15 watt tube amps can blow people out of the building.  (Trust me, I’ve done it before)  Even if you don’t think you’re running that loud, your amp can still cause problems in rooms with a lot of ambient reverb (like a room with concrete block walls).  This happens because your sound bounces all over the place, and that natural reverb makes your band’s overall mix muddy.

The solution many guitarists use for this is to isolate their guitar amp, usually by placing it in another room adjacent to the stage.  They’ll then put a mic in front of one of the speakers, (a Shure SM57 is a good choice), and run it to the sound board.  This gives you two benefits:  first it lets you turn up your amp as loud as you want to get good tone, and it also lets your sound guy control your volume level and eq in the house.  (Note: happy sound guy equals less stress…) 

If you don’t have a room near the stage, you still may have a few options.  First, look for areas on or near the stage that are “more isolated” and mic your amp there.  (Make sure it’s away from the general seating area.)  If your speaker is within 10 feet of a wall or hard surface, you may want to put some foam, blankets, carpet sections or pillows a few feet in front of your speaker to help absorb the sound.  If all else fails, try positioning your amp near the back of the stage, turn it backwards or sideways, and mic it.  Then look for anything you can to place around it to absorb the sound.   

If you use your amp as a monitor, isolating may take some getting used to.  Stick with it though.  As frustrating as it may be at first, it will ultimately give your band a better sound. 

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Responses

  1. you have some good points here. one of the drawbacks to keeping your amp so far away is that you have to run long sections of cable. it’s always good to make sure you have a buffer pedal on the front end to combat any signal issues when bypassing pedals and heading direct to the amp(s).

  2. yeah this worked very well for our show at the church a few weeks ago. 40 watts of fender tube in that room was not going to be tolerated without isolation.

  3. Might be worth looking at the use of attenuators in tis article. I use an attenuator to solve the same problem, I get to use my amp on stage as a monitor and there is heaps less infrastructure to deal with. Attenuators get a lot of bad press because people think they kill tone. They do have an effect but not so much you can actually notice, but certainly not as much as running your rig through miles of cable and the desk. Highly recommend people try them out. Tube amps only of course. I run my Fender HRD at home for practice on 12, sounds AWESOME and my family sleeps through it in the next room. Interested? :)

  4. dos puting pillowss in back of your amp help the sound?

  5. It can, the one thing I’d be careful about is making sure your amp still has a good amount of airflow to it. Amps that are confined with no ventilation get hot enough to fry eggs!!!

  6. Hey I just wanted to say THANK YOU for doing what you do soo well. I took your advice and isolated my ATOMIC 212, mic’d it up with a shure something and voila.. everybody in the team was very happy not facing 2 x 12′s during practice and our first worship was a blessing to all who participated. Ironically, it was our worshipldr who was at first a bit hesitant with the idea.. but once I and the sound-guy tried out a few configurations, we all agreed it was the best control and sound possible. Plus having the Mic in the other room gives me an opportunity to play around with the placement and distance from the amp and this really opened up my tone in the mix.. God Bless you and all the participants for first having a heart of worship and then dishing-out some great advice. Keep it up!

  7. I own a 60 watt Fender tube amp and as expected, I couldn’t get a good sound at a reasonable volume.
    Recently, I ran across a volume box on eBay from an outfit called “Omnisonic” (http://myworld.ebay.com/omnisonic/). It is basically a volume attenuator designed for tube amps. It is far less expensive than other volume attenuators I have run across, so I decided to give it a try. It really works great – I’m able to get good distortion from my amp at any volume. Anyway, just wanted to pass this on.

  8. Thanks for sharing this information. Really is pack with new knowledge. Keep them coming.

  9. Roger the above comments about volume attenuators. I recently acquired a used THD Hotplate for my 60W Fender tube amp. It is quite marvelous how much better the amp sounds turned way up. With the attenuator, I can do it at volumes that make no one’s ears bleed and do not result in visits by law enforcement personnel. I had never really heard my amp’s full and very toneful voice before. I highly recommend!

    Rock on,
    RT


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