Just a quick question... if your amp combo or cab has an open back or a section of the back open is it true that it will change the sound if you cover it? just wondering my friend told me but i'm not sure.
Last edited by GuitarNewbee at Jul 17, 2013,
Yes. The closed space will reduce the high end from coming out the back end of the cab. it also can create more of a pressure change behind the speaker (fairly small, might I add), which would make the top end less pronounced.
Having a close-back speaker will definitely give you more bass response and a "bigger" sound since it is pushing more air out the front rather than the back.

You should try it and see what you like better. Just be careful (if it's a tube amp) that you don't fry those tubes.
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This is terrible advice. Even worse than the useless dry, sarcastic comment I made.

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it can round off some of the highs nicely.
I wondered why the frisbee was getting bigger, then it hit me.
Technically closing the back of the speaker will have two effects. In an open back speaker the lows which are omnidirectional come round from the back of the speaker and cancel the lows from the front so you lose bass compared with a closed speaker. Creating an airtight volume of air behind the speaker acts as both a spring on the back of the cone and also as a resistance to movement. The main effect of this is to improve damping of the cone (like the dampers in a car damp the suspension) which means the speaker will more accurately track the guitar and tighten up the sound.

there's a third effect which is that you now have a reflector behind the speaker which reflects a few mids through the cone and will change the sound a little.

The increased highs of an open cab are actually due to a change in the tonal balance, You don't actually get anything extra for free.

Like the guys say you can try this out fairly easily to see which sound you prefer. Check if there is a shelf between your amp and speaker if you have a valve amp though as you don't want to restrict air flow.

If you want more detail have a read here http://www.ultimate-guitar.com/columns/gear_maintenance/cabinets_for_guitars.html

Last edited by Phil Starr at Jul 18, 2013,