Single channel lm3886 kit from chipamp.com, anyone interested?

[RDV]

The PCB isn't really helpful to me. I am a perf type.

Oh yeah, me too, but with the PCB you're almost guaranteed a working amp, and with perf you're almost guaranteed to fail without a proper layout. Oscillation that you can't even hear will make it overheat.

It... well... uh... happened to me.

RDV

[fixr1984]

Hey joe other than the $40 for the kit, how much extra do you have invested it it?

[Joecool85]

Including shipping on stuff I spent $30 on the heatsink, $55 for the transformer and $6 for the power cord.  I think thats about it.  I could have used a substantially smaller heatsink and transformer, and if I had gotten the transformer on eBay that would have saved money too.  Plan on spending around $50 + cost of kit.

[Quackzed]

this seems like a cool idea if you want to try out different preamp ideas, like all those cool amp emulating jfet thingys over at ROG... ive been lurking around pawn shops and places like that looking for a cheap home stereo or mono amplifier to use as the poweramp section for just this reason, a 50w chip amp seems perfect for this... "dude check out my ss  profesor tweed/matchboks/I8/english channell/ummble amp!!!  mwahahaha... stage center reverb anyone? im' gonna make mine light and portable!

[Nasse]

I bought cheap ready made new solid state transistor "PA" amp for about 150 euros (+shipping), 2 x 240 watts on 8 ohms R.M.S they claim and more with 4 ohms. It has big toroidal transformer and looks nicely built. Sound quality is "pleasant" sounding for me. One thing only that annoys me it is fan cooled when playing low volume at home. Good quality and nice price that they do in China.

I have seen a LM3886 kit with components and pcb without heatsink and transformer for much less than 40 euros, but I think that cheaper design maybe has some slight but annoying hum problem in the pcb design (my brother had one made for him, and what ever we did, we could not get rid of slight but annoying mains hum. I have similar amp done on another pcb design and it is quiet, no hum at all). And power supply and other components were not the best audiophile quality, but cheapest you can get on that cheapo kit...

I would happily pay 40 euros if I know I will get good or exellent audiophile quality reliable amp, and someone has done the hard long work designing and making high quality optimal pcb and collecting just right parts for it.

I know when my ready made PA amp gives the blue smoke out and dies some day, it maybe is impossible or too expensive to repair it, and I need some cash to replace it. But my self-made 3886 amp, I can always fix and troubleshoot myself. I can not think much easier or better cost/performance value chip amp, if you want to do it yourself, a home studio monitor amp or for guitar amp or hi-fi.

[Joecool85]

It's $40 US dollars, not euros.  Sorry for the confusion.

[Nasse]

1 euro = 1.1914 dollars (Bank of Finland value today)

Close enough 1:1 for me, in this case, so no problem

[christobean]

to avoid the $40+ of the transformer, i am going to try to use a 12v power supply from some old computer thing i found, this would work just at not as much power/watts, right?

[RDV]

to avoid the $40+ of the transformer, i am going to try to use a 12v power supply from some old computer thing i found, this would work just at not as much power/watts, right?

There's a minimum voltage of 18+/- that must be fed to an LM3886 to make it work. There are some  other chips that will work with less.

RDV

[PenPen]

With all the talk of amps lately, I wish Aron would make a subforum for Amp talk. I want to build a very basic transistor power amp, low wattage, to get my feet wet, but dont' want to post OT here. I think its enevitable that eventually many of us would progress to amp building, having a forum here that is easy to navigate and we are familiar with everyone here would be awesome, I think. 

[RDV]

With all the talk of amps lately, I wish Aron would make a subforum for Amp talk. I want to build a very basic transistor power amp, low wattage, to get my feet wet, but don't' want to post OT here. I think its inevitable that eventually many of us would progress to amp building, having a forum here that is easy to navigate and we are familiar with everyone here would be awesome, I think. 

I think it's a great idea.

Some might argue that these chipamps are just high powered op amps(they are) and as such are just another component of an effect called an amplifier.

There is a forum dedicated to these, but really only when they are being used as audiophile stereo amps. It's at www.diyaudio.com. There's a lot of good info there between the gobbledy-gook.

If Aron would agree to this, it would literally be the 1st of it's kind. The reason I got so excited about my chipamp guitar amp was because it felt like I was on a frontier of something(probably delusions of grandeur) that not too many people were doing. I know if we got some of the great(er than mine) minds around here on it, we could figure out some ways to make them a bit warmer and more paletable for guitar.

I especially feel this could interface with the stuff that's going to come out of the Digital Forum.

Let's go!

RDV

[Joecool85]

I too think this is a great idea.  As far as making it more warm, I think it has more to do with the preamp in front of it than the lm3886 power amp itself.  I'm up for modding though.  I have a spare amp board to mess with and I talk to Brian almost every day now (helping him with a lm1875 prototype right now), so getting parts isn't an issue. 

Right now I'm using the lineout I made on my K20X to go to the amp, it sounds pretty good.  I'd like to build a separate preamp eventually though.

[Connoisseur of Distortion]

The PCB isn't really helpful to me. I am a perf type.

Oh yeah, me too, but with the PCB you're almost guaranteed a working amp, and with perf you're almost guaranteed to fail without a proper layout. Oscillation that you can't even hear will make it overheat.

It... well... uh... happened to me.

RDV

did you try putting a capacitor in the negative feedback loop, to roll off this devil frequency? seems like a fairly basic fix, unless there's something i am missing...

[RDV]

The PCB isn't really helpful to me. I am a perf type.

Oh yeah, me too, but with the PCB you're almost guaranteed a working amp, and with perf you're almost guaranteed to fail without a proper layout. Oscillation that you can't even hear will make it overheat.

It... well... uh... happened to me.

RDV

did you try putting a capacitor in the negative feedback loop, to roll off this devil frequency? seems like a fairly basic fix, unless there's something i am missing...

There has to be small value(.1µF ceramic preferably) bypass caps on the +/- rails that must be near the chip itself(some even solder them directly to the pins), once I got them closer the oscillations stopped and the amp ran cool. Many people have actually built these things point to point on the pins of the chip 'hanging garden style'. The tighter the layout, the better seemingly. If you're good at perf it'll be a snap as long as you get the filtering right as the amp itself has very little circuitry.

The power supply is the end-all and be-all of any power amp. The rest is usually quite simple really.

RDV