#1
I practice in a finished room in my basement, and the amp I practice on (Hartke GT60c 1x12 60 watts) can have either the top or bottom, or all of the back removed. (There are two seperate wooden covers on the back that can be removed independently of each other) The other night I tried playing while standing in different parts of the room, with both the top wooden plate removed & on the back of the amp. Also tried moving the amp around in the room, sometimes with it up against a wall, sometimes in the middle of the room, sometimes on a chair, etc.

Getting it off the floor minimized the bass and "boominess" of the tone. Putting it close to a wall with the back open brought more "richness" and an "enveloping" quality to the tone. With the back closed up it projected and focused more but I thought it sounded thinner. I've always heard that closed back amps have more bass but that wasn't my experience, the bass seemed to be choked off some with the back closed. I did try it with the back completely off and didn't like the tone, it seemed to lose definition.

Anyways the point of trying this stuff is to get some ideas about where to place an amp when playing live, and whether to close the back or not. I'm interested in knowing what others are doing and what tone you're getting ... on the floor, open or closed back, against a wall ... what sound you're going for, etc.

Thanks
#2
Awsome thread. I have always wondered about this. My amp is all closed but its broken,lol, so i got to get a new one sometime. I also want to start building them so I didnt know which way to make the back.
#4
Nice, I don't think having a closed back necessarily gives you more bass, it just means the sound's a bit more focussed and tighter so the bottom end stands out a bit more. Personally I like open back combos, they seem to fill the room a lot better than a closed back amp would, although if you're being mic'd at a gig that doesn't matter too much. I usually have my amp on the floor, never really messed around with putting it on a stand or chair. I think the extra bottom end from having it on the floor is handy since I have a bright amp.

Quote by Horlicks
I have a question:
Can you open a closed back amp safely?


I don't see why not, you'd have to open it up and check if you'd be cutting through anything or exposing any delicate parts beforehand, but I don't see why it wouldn't work.
A dwarf might hear you. What then?

My Music
#5
Quote by timi_hendrix
Nice, I don't think having a closed back necessarily gives you more bass, it just means the sound's a bit more focussed and tighter so the bottom end stands out a bit more. Personally I like open back combos, they seem to fill the room a lot better than a closed back amp would, although if you're being mic'd at a gig that doesn't matter too much. I usually have my amp on the floor, never really messed around with putting it on a stand or chair. I think the extra bottom end from having it on the floor is handy since I have a bright amp.


I don't see why not, you'd have to open it up and check if you'd be cutting through anything or exposing any delicate parts beforehand, but I don't see why it wouldn't work.

Well, say if I cut the back of my 4x12 in half, what sound differences would there be?
#6
In a live situation I would think that partially open would be the best. That way if you aren't mic'd you would spread the sound better. If you are mic'd it really won't make a difference either way I'd reckon.
I don't give a shit if you listen to me or not
#7
Quote by Horlicks
Well, say if I cut the back of my 4x12 in half, what sound differences would there be?


I can't say exactly 'cause I've never heard a half-open 4x12, but my guess would be that the sound would be a bit more "open" sounding, you might lose a bit of tightness, and you may find it projects a bit better.

Your best bet is to go digging around GB&C for answers, or even just go for it but make it so you can put the back on again if you don't like the sound.
A dwarf might hear you. What then?

My Music
#8
If the amp is miced I guess it wouldn't matter much, because the amp is probably being used only as a monitor. (Does anyone use a separate monitor when their amp is miced?)

At least on the Hartke amp I practice on and sometimes play live on, there are two large wooden tolex covered "plates" on the back of it. They are both held on only by a few wood screws and can be easily removed. The amp is at the top of the cabinet and the back of the amp isn't covered by the plates, so there isn't much behind the plates other than the speaker & speaker wires and a couple coaxial cables going to some kind of block on the floor of the cabinet. I'm guessing the reverb unit is inside the block but not really sure. Anyways I'm leaving the top plate off for now because I think it sounds a little better. With the top plate off it's also a convenient place to put the power cord, footpedal, and music folder if moving the amp. I tried the amp with both rear plates removed and it didn't sound right to me. Still not sure if I want the amp elevated off the floor, for some songs there seems to be too much low end response if it's sitting on the floor.
#9
A furniture dolly works well for getting an amp off the floor, just a couple inches is all you need.
I don't give a shit if you listen to me or not
#10
Quote by timi_hendrix
I can't say exactly 'cause I've never heard a half-open 4x12, but my guess would be that the sound would be a bit more "open" sounding, you might lose a bit of tightness, and you may find it projects a bit better.

Your best bet is to go digging around GB&C for answers, or even just go for it but make it so you can put the back on again if you don't like the sound.

I might just saw it straight in half, then the bottom half can be screw back on if I need it
#11
I wouldn't do it unless you are going to seal the bottom part of it completely. Certain speakers work really well with open back, some are more partial to closed back. Cleans and mild OD I really like thru an open back, but rock and metal, I greatly prefer the tighter bottom of a closed back sealed cab. Porting is one thing, but just hacking the back panel in half is just going to make an open back 4x12. Something like the Roadking cabs which have a sealed half would be more effective IMO.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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