Hi, im looking around for plans to make a solid state pratice amp.
Looking at 30-50W maybe?
I play mostly metallica, acdc etc.
Can anybody help me out?
Thanks
Your best bet would be to build a bridged LM1875 poweramp or a single LM3886 poweramp setup. Either way I could probably set you up with a cheap set of boards.
As far as pre-amps go, you might want to look into various distortion pedals that you could build into your amp.
Rock'n'Roll,
--Andy
Righto, im not to sure what you mean by "bridged LM1875 poweramp or a single LM3886 poweramp setup" im guessing they are some sort of setup, im only like a beginner to electronics.
I found this amp http://sound.westhost.com/project27.htm but its 100W and im not sure if I would need one that big,not looking for a loud amp, ,I just want it to sound good and cheap.
So yea Im kind of looking for instructions as well
How much would it cost to make the one you mentioned?
Thanks
If you did a stereo LM1875 it would cost you $10 to get the boards and chips etc, normally around $10-20 for a heatsink on ebay and 20ish for transformer. So plan on $50 to get you going. Normaly the boards/chips would cost more, but I got some for free and then you just pay shipping plus a couple extra parts that didn't come in.
As far as being a beginner, thats not a problem. Just less than a year ago I was too. Sometimes I'm not the best at explaining everything in detail right off. The good news is, we have a bunch of smart people on here that are great at answering questions. SO, ask away!
A good resource is the wiki btw. The link is at the top. Also, it is good to read the stickies in the power amp and preamp sections of the forum.
Exactly how loud do you want it to be? If this is just a amp for practicing around the house, you could probably get away with using a single LM1875 which would push about 20watts. Then you could use the preamp from that link you provied.
Rock'n'Roll,
--Andy
Sweet thanks mate,
ive decided to mave a few stomp boxes first.
How close would that solid state amp be to sounding like the amp in the link below with a distortion effect pedel?
http://ax84.com/dp.php?pg=projects&project=p1-extreme&file=/media/ax84_m269.mp3
Yea not loud at all, Just so I could play in my room and maybe sometimes with mates. No gigs lol.
Just the important thing is i want it to sound good, i have a 10W ashton amp atm but it sounds really bad with gain turned up, havent had a distortion pedal on it yet, will be interesting to see how much better it will be.
Are you ever going to want this thing to sound clean, or is this a distortion only amp? I mean you said that you like Metallica and AC/DC, so I'm assuming you'll maily be playing with distortion, but of course, it's always good to be able to have some clean sounds.
Rock'n'Roll,
--Andy
Yea i would like it to be clean as well, but yer most of it will be distortion.
Would it be a good idea to just have one clean chanel on the amp and then have the effects via stomp boxes?
Yessir - quite an excellent idea!
Rock'n'Roll,
--Andy
Sweet, so what type of voltage would be needed from the transformer? the same 35V from that other 100W amp?
it will be a cheaper option to make a smaller wattage amp will it or not really?
Well, that 100watt amp uses transistors for the power amp. It could be alot easier (and less expensive, I think) to use an op-amp. One opamp could replace several transistors. The highest wattage you can get out of any opamps that we here at the boards use is 68watts, and that's using a LM3886.
Rock'n'Roll,
--Andy
Righto, how much cheaper would it end up?
would you have to use bigger speakers for the 100w amp?
Are the speakers expencive?
I don't know exactly how much cheaper it would be, or how much speakers cost off the top of my head. I'm pretty sure with most speakers though, it's the impedances that need to mach, as power handling shouldn't be that big of an issue. The actual size of the speaker (8" speaker vs. 12") doesn't depend on the wattage of the amp at all.
Rock'n'Roll,
--Andy
you need speakers rated for the right performance, rating does indeed not depend on the size of the speaker. a new jensen10" 25W one should probably cost some 40-50 bucks.
if you can find a defective combo (preferably w/ a working speaker) you should get that and gut it- it can save you the bother of building the cab and the chassis (12 hours of work)and you can concentrate on the electronics. furthermore you get the switches, knobs, etc almost for free, possibly even a suitable transformer.
If you want a "quiet" practice amplifier it's better to use a speaker with low SPL rating. The power rating of the amplifer itself really isn't that important - it's all about the speakers. In my opinion, you'd better build a 60 - 100W amplifier instead of low power one. Why? Because you probably end up needing one after few years anyway. If it's solid state, you can (without loss of tone) make this amp as quiet as any amp from 5 - 25 W range just by adjusting the volume knob. Remember the speaker thing: When you need more volume just plug it into a high SPL rated speaker system and have lot more headroom than 5 - 25 W amplifers can provide. Just make sure the speaker can handle the power: The tone of voice coils deformed by excessive heat is not very pleasing. By the way, when coupled with ordinary guitar speakers even 5W amps are too loud for apartment use. I practice with a 1/2 watt amp (it has a 3" speaker") or with a 12W amp (8" speaker) with the volume knob at one or two. As a recording amp, I crank the latter to 5. If I'd want to play with a metal drummer both amps would be insufficient. Quiet practice amps would really need less efficient speakers, such as hifi speakers. Unfortunately hifi speakers have a very flat frequency response while guitar speakers roll-off at 5kHz.
Is this a price issue? If you think you can DIY cheaper you are probably wrong. You can, of course, but it means that you have to salvage parts from equipment thrown to trash cans etc. This is actually pretty fun and I've done few great discoveries this way lately. If you are able to get the heatsink, mains transformer and perhaps even the speaker for free then damn right it will be cheaper. If you buy them the price is perhaps even higher than buying an amplifier.
Chip - Discrete? Chip amps are easier to build and requirement for parts is smaller. They have built-in protection circuits and thermal compensation. Their power ratings are also smaller, perhaps even bloated, since the smaller die area can not get rid of the excessive heat as quickly as the larger die area of few transistors can. I'd choose discrete because it's much more educative to learn how the circuit works, how to thermally compensate the bias, how to layout a PCB etc. After acquiring such knowledge you have a lot more options in tweaking or expanding the design than you have with chip amps. This can take years though, and if you want to quickly build something that actually has a good chance to work on the first powering up then build a chip-amp. Nice alternative for LM series chips is the TDA series. Most of them show a PCB layout for the application circuit in the datasheet too. I recall that a TDA7294 was about 100 watts.
You could use a LM4780 which would give you 120watts.
And for an easy to build, great sounding stompbox, try my 5th Gear Overdrive. It goes from a middle overdrive sound to a pretty decent distortion.
http://wiki.ssguitar.com/index.php?title=5th_Gear_Overdrive