dimming the speaker

[nopainkiller]

I made a little amp out of a lunchbox and the speaker is pretty bright. I read an article on runoffgroove where the guiy made an amp out of an old macintosh computer. He said he placed a 5uf non polariozed cap over the speaker terminals and this fixed his brightness since he used a small speaker.

The amp I built is a bridged design tho, so the negative speaker terminal goes back and inbto the second lm386. I'm not sure placing a 5uf cap across would do the job. Is there anything else I can do like this?also why would the cap need to be non polarized for what he did?

[defaced]

Try placing padding inside the box. This is used alot on car speakers to bring out the low end.

[nopainkiller]

ah, ok. Would that really take care of the brightness? The amp is in a tin lunchbox, and the closed lunchbox provides ALOT of bass. I actually had to change the input caps. There are switchable input caps. The value in the original design was .047 uf. Now it's .01 uf or .022 uf. Hm also it's pretty cramped in there

[eidlyn]

You can read my long winded explaination or just skip to the solution. I went off a bit, but its all useful.

EXPLAINATION;
You get that with all amps, actually. the reason you don't notice is that you probably don't stand right in front of your Marshall stack. Often.

When the speaker is pointing directly at you, you get a lot of the treble, but when you're too the side the treble frequencies are usually absorbed by the accoustics of your room rather, and the lower frequencies are reflected and carried. Thats why the guys in the appartment next to you sound like a jet engine when they party or play, but they hear the crystal clear highs on "Dream On". Try it with your larger amp. If you walk in a circle around your amp and play, you'll hear it getting higher as you're more towards the front.

Weber designed this device that can be attached in front of speaker cones that reflects the higher frequencies back into the cone so they won't dominate your sound. its just a circle that goes in front of the magnet. SRV or Prince, i don't remember which, put ducktape on the grill cover of his amp instead. I stuck a 2 inch CocaCola fridge magnet on the metal grill cover of my Valvetronix. When I take it off, its all fun and games. When I put it on, my roomate gets all upset because his monitor is shaking in the next room. Thats on 1/3 the Wattage.

SOLUTION;
If you don't want to cut holes in your lunchbox cover, put ducttape, not on the cone, but across the front of it, so it covers the magnet. You can vary the size of this depending on the amount of treble you want to come through. Or whatever material you want in front of it.

If you don't mind cutting holes in your lunchbox cover, the most economical, easiest to pull off and most asthetically pleasing method is to cut holes in the side of your lunchbox to let the mids through, and maybe a few on the top for treble. As you know, the closer to the center you get, the more treble will come through.

PS; i don't know what you do with a polarised cap, but on your guitar, the tone knob is uses a non-polarised cap to ground in order to bleed off the highs. With a non-polar cap, they just syphon off different frequencies.

By the way, thats bloody brilliant to make an amp like that. I wonder if you could take it gigging at coffee shops and the like.

[nopainkiller]

thanks! do you mean the macintosh amp or my lunchbox amp? You can see it in the other thread.

This thing really is loud, and when a drummer is using brushes this thing can really jam. I was really surprised at how loud it was when I first made it, and then especially when I added the two boosters, the LPB-1 and the FETzer valve,

I do play right in front of it. I don't really wanna cut holes in it, since there's actually no room! Knobs and switches everywhere! I don't want to cut into the back because there is artwork there. The Last Supper! I'll try tape over my speaker. The thing is just sitting on the front of the lunchbox in a round hole, hot glued in placed. No speaker cover or anything. its just 3 inches wide

[eidlyn]

both actually, athough the idea of carrying an amp around in a lunchbox is even better than the first. Could you make a valve amp out of that? That would be loud as hell.

[nopainkiller]

I was planning on putting in a tube input stage. I found this design called the matsumin valve caster. But If I put a tube in there I would want it to be on display outside the box. There is absolutely no room after the FETzer valve and the LPB-1. Plus it would need 12v so I would have to put another 2.1m jack.


Anyway I put duck tape over the speaker. Had to basically cover the entire thing. Colored it black. It did take the ice pickyness out of it. The speaker is ohnly 3 inches wide because there is another amp right beside it. Itr's actually acombo guitar/bass/drummachine amp.

The last thing I'm really serious about addind to it is a stand. Like a metal arm to go under it so it would be a little less than a foot off the ground. Then I'm gunna buy a smaller drum machine, one of the really portable ones, and mount it right under the lunchbox. So I'll have the drum machine everywhere I bring the lunchbox~!

[Fretts]

This is pretty low-tech, but how about putting cloth of various thicknesses over the speaker, on the inside, where it doesn't really show?

[nopainkiller]

ah, I'vve thought of putting foam or cloth inside. But the thing is, is it's two amps. One for guitar and one for drum machine or bass. I want to preserve the bass for the drum half. I could put some just over the back of the guitar speaker. But there are also many wires. It's veryt clustered.