Diy bass amp.

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Hi all, I posted a similar topic in the Chip amps section and was advised by a fellow member to ask here for advice also.

I wish to make a bass amp as this will increase my knowledge on electrical stuff and also give me something usable at the end of the process.

I am looking to build a practice amp, no more that 50W in power, simply because it is for the house and maybe the odd garage jam, nothing more.

I have been thinking heavily about a LM3886 power amp section as this chip can provide 50W of power. I wish to steer clear of tubes as I wish to gain some more knowledge before undertaking a tube project.

The amp needs to be able to do clean and distorted sounds, if I need to use a pedal then I do not mind as I can probably mod something or muster up a pedal specifically for the job. It does need an eq section in there and I would prefer a basic 3 or 4 pots (Bass, Mids, treble or bass, low mids, high mids and treble).

The circuits won't necessarily be simple and I do realise this, but the simpler they are the better, I work by the KISS principle as taught to me by my dad and granddad so keeping things simple is in my brain ;)

in terms of tones I need a good varierty but I want that rip roaring lemmy tone as well, so i need to factor that in (although i am not rich enough for a ricky and a marshall!)

If you have any words of wisdom or ideas, I would love to read through them

many thanks,

Bruce
 
Well I don"t know how simple it would be but you would start with a basic adjustable gain stage going into a 3 or 4 band active EQ stage then into a LM3886 Power amp stage , you could add a couple diodes at the output of the gain stage to give you a fuzz bass effect .....

If you wanted something simpler you could skip the EQ stage and add an FX loop and use an outboard EQ pedal or rack EQ ......

Cheers
 
Hi Guys

Lemmy's sound is predicated on a clipped output stage and some EQing ahead of it. He sets the bass and treble down a bit and cranks the mids.

Doing this in solid-state is pretty simple. The above suggestions for making a clippable gain stage using diodes is an easy start and allows you to get the sound without actually clipping the 50W output chip. EQ after the distortion stage will let you make the tone as crisp or fat as you want. You can build the whole preamp with three opamps, if you buffer the output of the diode stage into the EQ.

If you wanted to keep it really simple, you could do the first stage with variable gain and diode clipping, then a simple Tube-screamer style EQ stage with a single tone control, and a final volume before the PA. Just two opamps.

Since opamps have so much gain, you could also do a single opamp variable gain stage with built-in clipping into a passive EQ, volume and PA.

Opamps are pretty forgiving and can be made to sound however you wish. Fortunately with electronics you can use any path to get to your goal.

Have fun
Kevin O'Connor
 
Hi,

Hifi amplifiers have nothing much to do with musical amplifiers, as any
perusal of hifi amplifiers versus musical amplifiers will quickly prove.

Lots of tricks used in musical amplifiers and the only way to learn is
studying (and emulating) the schematics of other musical amplifiers.

rgds, sreten.

Look up TinaTi, an excellent free emulator.

FWIW I'd simply buy a good sounding small used bass amplifier.
In my case I learned more analysing what it did and how it
worked and how to fix it, than I would have done "designing"
my own bass amplifier, which would have cost a lot more,
and TBH a lot worse, reinventing the wheel is not good.

A used Ampeg BA112 would be a very good idea.
 
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There are a lot of really good tube amplifier kits. You get the experience, guaranteed result, and low risk. A bit more complicated, but as long as you're careful with high voltage, tubes are a LOT more forgiving than transistors. My first transistor guitar amp blew up a half-dozen times before I caught the RF oscillation on-scope, as it woudl blow a second after it started to oscillate. On a tube amp you see the tube get red, and you have minutes before permanent damage. If you do permanent damamge, you unplug it and plug in another. Tubes are really forgiving, surprisingly tolerant of idiots like me. And IMHO they just sound better, though admittedly for clean bass transistors can do OK. Small transistor bass amps come up all the time on shopgoodwill.com because people throw them out. If you want one, they're cheap.

With tube kits you hav eto be careful though. Many are designed to make particular kinds of distortion at low volumes, which is probalby not what you need for bass. Admittedly, for clean bass you need big output transformers, so transistors are a viable option.
 
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