Replies to This Discussion

Permalink Reply by John W on March 27, 2011 at 3:14pm

If the circuit is LM386 based, they'll almost certainly be fine, as far as power rating goes.  As to how they sound, who knows?  Build one amp first, see how it sounds, and if you don't like how it sounds get a different speaker.

 

Do you have a regular old book shelf speaker?  Like, an old hi fi one you're not using at the moment?  Don't take it apart, just hook the output of the amp straight up to the speaker as is.  That should give you a good indication of how the amp will sound with a "proper" speaker.

 

If you like how it sounds with the bookshelf speaker, but don't like your little computer speakers, get a new speaker. Old speakers are pretty cheap at second hand stores / yard sales / etc.

Permalink Reply by petey twofinger on March 30, 2011 at 5:07am

one thing to keep in mind when testing speakers is that they really do sound quite a bit different if they are not in some sort of enclosure . what i like to do is use a cardboard box about the size of the amp , cut a hole for the speaker in that , and then test it . like john said , you never know till you try , doesn't the micro cube use multiple small drivers ?

 

i am not sure but i have to imagine there is some trade off in the relationship to speaker size to battery life / heat on the amps chip .

 

i always look for a speaker with a hefty magnet , seems like there are a lot of pc speaker sets floating around these days . some of them have "subwoofer" cabs , heh . those are usually less than 6 inch speakers with chunky magnets , they LOOK like they could take a beating . not sure how the highs are though .

 

are you going to make a demo video ?

Permalink Reply by Rod Patten on March 31, 2011 at 7:07am

Well, posting anything except small pics is going to be tough. Broadband challenged here. Rural dial up connection can be a real pain. Send an email and I can look out the window and watch it running away.

 

I plan to build a little cabinet for the amp and speakers. I have the info printed out for building a Little Cricket and will try and do a really nice job on the cabinet. Probably use some bass wood from the hobby shop simply cause it will be easy to work with. They have a good assortment of brass and copper that may come in handy for guitar building too.

 

Should get to start rounding up bits and pieces for both the guitar and the amp this weekend.

Permalink Reply by petey twofinger on March 31, 2011 at 3:04pm

lol . . .

yeah i had wind up connection for a while here , isnt amp building a blast ?!

have fun !

 

 

Permalink Reply by Rod Patten on April 7, 2011 at 8:49am

Got a great start on the guitar and amp projects. Amp seems to be coming along faster though. But I am having trouble finding all the the parts to build the amp circuit. Mostly the film capacitors. I have the Noisy Cricket pdf from Beavis audio saved and took it along with me to Radio Shack and they had 95% of the parts. The parts list for the amp had a parts layout and a list of the values needed. That is where I got lost.

 

The film capacitors are listed on the page as 47nf and 100 nf. Looks like I need 4 of the 100nf and 2 of the 47nf. I looked at the smallbear site and tried a few searches for the values and came up with nothing.

 

I have everything else minus the film capacitors and the 1k linear pot. Gonna go a head and use the small computer speakers. Everything will fit nicely into a small cedar chest looking box I picked up at an antique store for $5.

 

Maybe an electronics 101 on the values of the capacitors would help? Or a part number to order the remaining parts?

 

See ya,

Rod

Permalink Reply by jacob hanley on April 10, 2011 at 4:43am

I am currently building the same amp and I got stuck on the same three things as you did. I found a capacitor conversion chart with a yahoo search. I think this is the answer and radio shack does carry the uf versions 47nf = .047uf and 100nf = .1uf  I am still looking for a 1k pot but I will probably end up having to order that from a online store.

Rod Patten said:

Got a great start on the guitar and amp projects. Amp seems to be coming along faster though. But I am having trouble finding all the the parts to build the amp circuit. Mostly the film capacitors. I have the Noisy Cricket pdf from Beavis audio saved and took it along with me to Radio Shack and they had 95% of the parts. The parts list for the amp had a parts layout and a list of the values needed. That is where I got lost.

 

The film capacitors are listed on the page as 47nf and 100 nf. Looks like I need 4 of the 100nf and 2 of the 47nf. I looked at the smallbear site and tried a few searches for the values and came up with nothing.

 

I have everything else minus the film capacitors and the 1k linear pot. Gonna go a head and use the small computer speakers. Everything will fit nicely into a small cedar chest looking box I picked up at an antique store for $5.

 

Maybe an electronics 101 on the values of the capacitors would help? Or a part number to order the remaining parts?

 

See ya,

Rod

Permalink Reply by Rod Patten on April 10, 2011 at 6:34pm

Thanks, found that chart and saved it for later use. Also found all the parts I needed to continue from SmallBear. Only thing I am leaving out of the amp project is the a/c adapter parts. I will try two 9v in parallel to double up the capacity of the battery power.

 

Did a little more work to the guitar too. Got the neck holes cut in the cigar box. But will have to find some real power tools to cut and drill the oak neck for the tuner pegs. I think a drill press and a few various bits will do the job. I found one half of a set of three in one tuners at an older music store that also does lots of repairs. Showed them my project and got the tuner part for $5. But it will take some careful drilling of the oak to make work and look ok. But I am taking my time and hope to get some more done in the next week.

 

Will try and post a pic of both projects sometime soon. Not much to see but a pile of parts right now.

 

See ya,

Rod

Permalink Reply by petey twofinger on April 11, 2011 at 6:54am

it would be nice to have a drill press , i end up having to "free hand" . one of the issues i have drilling thru wood is when i blow out the underside . when the bit pushes thru the wood will splinter with the grain . i learned to start very small , work my way up (with the bits) and also just drill half way thru , then flip and drill the other side . (you prolly know all this though) . another trick is to clamp a piece of scrap wood on the bottom , i understand this works well too .

 

if you have a link for the capacitor chart , i would like a copy of that for my private stash as well . i am planning on printing up some charts for resistors and caps , then "laminating " them (clear packing tape) , so if i spill beer on em they wont run .

 

if you have room inside the enclosure are you planning on mounting the power supplies in side there , then having a single AC in to feed them ? it would add to the weight of it , and convenience . if not a single 9 volt P.S. may suffice , as long as the milliamps are high enough .

 

i am curious about small bear , what is the shipping cost , how long is delivery ?

 

thanks

Permalink Reply by Rod Patten on April 11, 2011 at 7:15am

I just did a search for capacitor chart and got several options. I just picked one and saved it as a favorite in my bookmarks. justradios.com

Shipping was $4.50 and I ordered sunday and the site said it should ship within 2 days. Should have the parts by the weekend.

I have a buddy with a good drill press. Will buy a selection of bits and do the work at his shop. To help with chipping out, try placing a scrap wood under the neck. Or like you said, go in from each side.

Permalink Reply by Rod Patten on April 26, 2011 at 8:38am

Finished!.

Honest sound, has a grit mod switch for a little growl, volume, tone, gain. Easy build and a fun project. Worked out great in the small chest. Twin 9v power so I won't have to open it up so often. Speakers will work fine. 

Attachments:

• CBGamp1.jpg, 156 KB

Permalink Reply by petey twofinger on April 26, 2011 at 11:38am

i like the design layout , with the lid and the 2 speakers on the side . its a unique looking cbga . did you hook up the speakers in series or parallel ?

Permalink Reply by Rod Patten on April 27, 2011 at 9:04am

With the lid closed, you would never know it was a guitar amp. Except for the funny looking "key" hole in the front.

Speakers are hooked up parallel. I guessed that the speakers were 8ohm. Seem to work just fine. Plenty loud enough and sound good. If I need more power or effects I can plug the CBG into a larger amp.