350W Power Amp with LM3886'S

[odysseybmx414]

care to post a schematic if not of the whole thing then perhaps just the ground configuration(with the two diodes....etc)

 

[Cobra2]

Re: Re: Idle...

I'll guess you have measured the input current but that gives you 65 VA, but you'll pay for watts.

I used my "HiTec" digital-plug-in-the-wall-watt-meter !!!
(also shows; Amp / Volt / cost of running-computer / ....)

Arne K

 

[jaudio]

Re: 350W lm38---

I just proto-typed a bridged parrellel amp useing lm3875's 4 parrellel sets bridged for a total of 8 per channel, amp has less then .008 DC offset, only idles at 34 watts and produces 408 watts at .13 THD and is dead stable. Very carefull design in the PC board is key, most problems in single bridged and parrellel designs are input offsets and oscillations caused by impeadance variations. Referance signal to ground provide a low impeadance path for return , and dont use a dual tied bridge......

I have almost the same setup but instead of using lm3875s I used lm3886s in inverted mode with trimmers. My offset(.15mv) is just a little low than yours. I matched chips as best I could. The chips were within 2mv of each other after match and before any compensation. One piece of advice,when parallel bridging alway buy more chip than you need then match and match.

 

[InlineTwin]

Pushing it, +/- 42V and 6 LM3886s would pretty much get you there.

Power dissipated cannot exceed 30W for -TF and 40W for -T without forced air.

Use:
P=Vtot^2/(2*pi^2*(number of LM3886 in parallel )/ 2*load res.)

Then you can find the power out: Pout = V^2/(load res.)

Where V=Vtot/2

So, 84^2/(2*pi^2*(3/8)*8) = 30 Watts.
and 42^2/(8) = 220.5 watts.

So you only pick up 20 watts over four LM3886 at +/-37V.

If you force air over the HS then maybe you can get more power out.

 

[ttan98]

Is it possible to build a 350W rms (load = 8ohm) with LM3886's?

the AN-1192 have a 200W but that's not enough.

thanks
Jorge

this is the captain, "Scotty give me more power"

truly you don't need so much power, remember global warming is around the corner!