I want a practice amp that I can move around, but my budget is limited, and here in Chile the SS amps, that are decent enough, are way out of my wallet in this moment.
I am thinking of building my own amp for practicing, so anything between 2 to 10 watts it is perfect for me.
Hi there, I've built several DIY amps, including several chip amps like the ones you posted there. The first will almost certainly need a preamp (even if just a one transistor FET preamp. Search for "Tillman Preamp", and "Fetzer Valve" for good easy ones). Class D are great for battery power as they are low consumers of energy. However, if/when you drive them into clipping, the sound is horrible (like a burpy, stuttery, awful sound). It absolutely could work, but a lot depends on the preamp there. The power amp module will not contribute anything to the tone. You will need to make a battery pack that achieves as close to 12v as possible in order to get the best performance. I would use NiMH rechargeable AA's, so you will need 10 x 1.2v batteries to get your 12v. (NOTE: if you make a battery pack in this configuration, you can ONLY use NiMH. Alkalines are 1.5v each, so if use them instead, you will send 15v to the amp, which could pop the chip!). Alternatively, you could use a 12v sealed lead acid (SLA) battery (sometimes also called a "marine" battery, or a "gel cell" battery). Look for one with a decent amp-hour rating, but with class D, you should get pretty long life even with only 1-2 AH
The second one will "work" straight away, but if you are using a normal dynamic mic, I would lower the input impedance by putting a smaller value pull-down resistor at the input (I'm assuming that it will come with a standard 1 megaohm resistor there). LM386 amps absolutely sound great, I have built several. You will only get maximum 0.5 watts, so it will NOT be as loud as the first one. On the other hand, it will be simpler to build (no need for separate preamp), and will also operate just fine on a single 9v battery, which is loads easier than making your own 12v battery pack.
Well, if you build that tube preamp, you could no longer power off batteries, and then you'd have to find a suitable power transformer and build a powersupply filtering section and rectifier to send the DC to the poweramp. It's a big job for a beginner...
Honestly, 0.5 watts is plenty loud enough for bedroom practice. For a first project, you are better off keeping it as simple as possible. Buy the lm386 "guitar amplifier" kit, build it as is, and see how it sounds. Remember, you will need an 8ohm speaker cabinet too. If you have any thrift stores near you, check those out, and see if you can get some old used speaker for cheap (hifi speaker, car speaker, whatever you can find. For this application, it doesn't really matter what type of speaker). If it doesn't sound like what you want, then I can try to help you modify it a bit... But even if it *never* sounds perfect, you will only be out a very small amount of money...
What mic do plan to use? ---------- == I S A A C ==
Col! That mic should work pretty well with that amp module. Speaker has to be 8oh (lm386 doesn't really like 4ohm, and 16ohm will result in less volume), and simply has to be rated at least at 0.5w (most any speaker likely can handle this), but can, of course, be rated for more watts (no issue with that). You should be able to put that together without too much problems. One note: when you are done soldering, take a q-tip and some rubbing alcohol and make sure you wipe down the underside of the PCB to remove any run away flux from when you were soldering. 9 times out of 10, any "shorts" that cause the circuit not to work are from leftover flux making connections where they shouldn't be! Good luck! ---------- == I S A A C ==
i got a 15 watt tube radio for 15 bucks. 4 D cells make the tubes hot, i made a 90 volt rechargeable battery bank for the frame power. it wasnt very loud, so i just added a 3 watt velman chip amp with another 9 volt clip as a preamp. it sounds great now about as loud as my pignose hog 20. i could still plug it in but with battery power theres no hum. the speaker overdrives nicely. i dont think it needs delay. so 15 for the radio, 30 for the 10 bank battery charger 20 for the batteries that can be used in other amps. so 105 volts dc inside a box the size of a lunchbox. if the amp takes a dump before i recap it i have another radio ready to go. ive tried the chip amps in cigar boxes by themselves and they sound like crap compared to the effects you get with tubes. and nobody makes a battery tube amp. eventually i want a bassman but for price and portability i cant beat this. i may sell my pignose hog 20 now.
A few days ago a received my amp kit, and I build it!!
It came whit a volume and tone control, and I put a 4" 20 watts speaker that cost me about 2 dollars, and a on/of switch.
It sounds great, a lot of volume! When I first build it, I put a 2" speaker and it sounded very distorted, but whit the new speaker sounds way better. I tested whit an old Zoom 505, and using that rig I am able to get a much nicer sound than when I put my MIC directly into the amp. But I could not recorded that because the battery went dead.
This are some pictures of the amp, and something that I recorded (DIY-telephone-speaker-MIC -> impedance transformer -> Amp -> Digital voice recorder, 1 feet away)
Looks good, i often mess about with bottle O blues mic into my smokey amp, and put the smokey amp into an old toaster, looks and sounds ok, the player is the main factor whichever way you look at it.
Cool! Looks great and sounds pretty good too! FYI, if you were to get an even bigger speaker (8" or 10"), you'd likely get a bit better bass response... But it sounds good as is! Love the cigar box housing! ---------- == I S A A C ==
