YES! i,m now the proud owner of a working LM4780 amp

[zei]

I told my wife some time ago for some reason that i wanted a new stereo. Her respons was,, we already have one and new one is expensive..
So i said,, i,ll make my own.. Her respons was : you are an idiot. hehe. Well, i had to prove her wrong.. so with no knowledge or anything i read and searched this forum over and over again and now.... she has changed her mind... Amp is working.. Speakers almost done and Preamp on the way..

Sorry no pictures yet.

I spent 2 hours last night trying to figure out why there was no sound.. Well.. after intense searching this xlnt forum, looking 100000 times at the schematics i found out why.

I had forgot to put the "mute resistor" where it should be.. me=stupid

I know you guys have heard this lots and lots before but, this is a truly great feeling.!

My first DIY and it just works.! looks ridiculous though.. lying on my floor, no heatsinks, no case.. but i,ll deal with that now.


and when i,m all done.. ( before christmas ) .. i,ll post some nice pictures of the whole system..

Thanx alot to all of you! Peter, Brian, Russ, Carlos and all noobs that posted questions so i could find out what was wrong.

THANX!!

/A very happy newbee

 

[Nisbeth]

Grattis! (Congratulations )


/U.

 

[zei]

A small concern about heat...

I,m not runing it with heatsinks yet ( just running it for a few seconds to test)

However, the chips are getting very hot. as soon as i plug the power they are hot.. i can touch them but i would,nt want to keep my finger there for a long time..

Is this ok?

 

[pinkmouse]

What schematics are you using? What voltage rails?

The 4780 does tend to run hotter than other chip amps, probably because of the power density required. Even for testing, I would use some sort of heatsink, even if it's just a few square cm of ali plate. Better safe than sorry.

Have you checked for oscillation?

 

[zei]

It,s the kit from audiosector..

I dont even have a MM so i cant test the rails or anything..

And oscillation i dont know i to check..

well.. it sounds veeery good.. no noise, crisp ,sharp, fast ..

Its just the heat that concerns me..

how can i check for oscillation?

/Z

 

[pinkmouse]

Buy a meter- even if it's only a cheap one. It makes life so much easier! If your amp is the Audiosector kit kit, oscillation is unlikely, and can only really be tested for with a 'scope anyway.

I think you just need some big heatsinks, even just for testing.

 

[zei]

Ok thanx.. i,ll get a meter asap..

and i will install heatsinks

 

[zei]

Ok,, i have,nt got any heatsinks on yet so i do not dare to listen for longer periods..

But i most say that the sound is just getting better

And my source is the headphone out from my laptop.!

just great! How good is this going to sound with a better source an good speakers!? wow

thanx again

 

[wes-ninja250]

A voltmeter, IMHO, is a necessary tool for building amps... without a voltmeter, you cannot check for high DC offset.. which can kill your speakers.

And even cheap speakers are worth more than an adequate meter.

Wes

 

[peranders]

Ok,, i have,nt got any heatsinks on yet so i do not dare to listen for longer periods..

Without any heatsink those IC's get hot

 

[Lamicz]

Hmmm, without any heatsink? IMHO it is quite risk. IO has overheating protection but I thing it is not good idea to test it like that . More, this IO is getting really very hot, even if not playing. It is adequate for push-pull AB class (am I true?)...

 

[enzedone]

Sweet As

It's such a great feeling to complete an amp, but if your like me, you will want to do another. I'm still trying to get another project up and running, but this amp building is not rating well on the D.A.F scale (domestic approval factor). Ahhhh the joys of married life.......
One was o.k, but two? well thats a whole different ball game. You single guys with dissposible incomes enjoy it while it lasts.....I'm off to put the washing out...whats that saying again? a womans/married mans work is never done..hehehe.