Need to drive 100w-ish into a 16ohm load, bridged LM4780?

[J M Fahey]

Yes, of course.
Stripboard is great and I love it.
I'll draw it and if I have some free time also design a stripboard with that great DIY Layout creator.
I use the "old" Windows-only version, not the "new-improved" Java one, which scratches me the wrong way.

[joecool85]

Yes, of course.
Stripboard is great and I love it.
I'll draw it and if I have some free time also design a stripboard with that great DIY Layout creator.
I use the "old" Windows-only version, not the "new-improved" Java one, which scratches me the wrong way.

Excellent.  You have chip points coming your way my friend :-)

[J M Fahey]

I always knew that bringing an apple to the teacher often meant better grades :lmao: :lmao: :lmao:

[J M Fahey]

OK, here's the bridger on Veroboard.

Now you have no excuse to avoid building it
Remember it's top view (component side).
Make the board somewhat larger to be able to drill a couple 1/8" holes to mount it or use double sided foam tape.
Be careful to avoid shorting tracks with bolts, nuts, etc.
Cut tracks as needed and check continuity (well, lack of it).
Bridge at least a couple TDA20xx or go for the Olympic gold and use a couple LM3886 or TDA7294.
We're talking serious power here.
Good luck and post your results.
PS: I've triple-checked the layout, but I encourage hawk-eyed friends to have a look; suggestions and corrections welcome.
PS2: of course, if you want it to sound good, you *need* to use Platinum Paper in Oil (white whale oil of course) capacitors, ground oak carbon resistors, Ming Dynasty Silk covered wire, lead-less tin-less flux-less organic solder and Vero Board made by a girl called Veronica.
The NOS 1964 vintage, germanium TL072 version is to be preferred, of course. :lmao: :lmao: :lmao:

[joecool85]

Ok...so the preamp would go into this circuit, then that gets hooked up to the two amps...how?  And how do you wire the +/- from each of the two amp circuits to go into one speaker?

I'm pretty stoked about this, because it sounds like if you built it right you could have jacks on it and randomly bridge any stereo setup you want in a matter of seconds.

**edit**
Oh yeah, I'm going to test it with a stereo LM1875 setup.

[J M Fahey]

Hi joecool.
Happy that you could clean quickly that virus.
This board shows one ground at the input jack.
If everything is in the same chassis, you run ground wires from the power amps to the main ground at the power supply, another from the bridger board, another from the preramp board, so all 4 boards are grounded to the PS.
Then you only worry about the signal/hot wires:hot from preamp out to bridger in,  hot from Out+ to one amp, hot from Out- to the other amp, and the speaker goes floating from one speaker out to the other.

[joecool85]

So the neg input and output of each power amp would go to ground?

[J M Fahey]

Yes.
Signal inputs have one pin hot, one grounded.
Speakers go from the in-phase amp hot to the out of phase amp hot.
Neither pin is grounded.
Power amps are grounded to the power supply, they may have only one ground pad per board or have two separate ones, one for input and one for speaker, ground them if so, but do not connect any speaker lead to them.
Do the LM1875 drive 4 ohms each?
If not, you'll need a 16 ohm box, as in the post header.
2xLM3886 or TDA7294 can easily provide 150W RMS into as 8 ohm speaker.
Something like that is made in the very loud Powerblocks.

[joecool85]

LM1875s will comfortably drive 4 ohms.