Off-Grid Party Sound Systems

Step 10: What you need

to make the fully integrated 12V amp + speaker, you need:

- speaker
- stereo amp
- crossover

Check the system diagrams below.

When the crossover comes after the amp, then it has to be big to handle the full amplified signal, and it has to waste power to equalize the tweeter and woofer volume.  But, we always need to split apart the highs and lows from the mp3 player and direct them to the tweeter and woofer.  So the secret to a good integrated amp setup is that we put a small crossover BEFORE the amp.  this gives us an un-amplified tweeter signal, and an un-amplified woofer signal.  we route one of those to the left channel input of the amp, and the other to the right channel input of the amp.  Then on the amp output side we wire the left channel direct to the tweeter, and the right channel direct to the woofer.

When we put the crossover before the amp, we can also use it to adjust the volumes of the tweeter and woofer, and also to combine stereo to mono if we want to.  operating on the un-amplified signal these can all be done without power waste.

So, to make the integrated 12V amp + speaker you need:

- speaker(s)
- 1 stereo amp per speaker
- 1 crossover per speaker

The stereo amp can be whichever T-amp you like.  My build photos mostly show the TK2050 amps.

The crossover - I made my own circuit for this - see my monoXover project.  It is a fairly simple circuit so you can build it yourself from parts.  If you would be interested in buying a monoXover DIY kit, let me know.  Another option is to use a mixing board.  Some small mixing boards in the $50 to $100 range can provide this crossover functionality, i haven't tried this myself but it looks possible.

Comments

[panasuiks]

I'm running into the same mental block that tamadoctor did. Both the woofer and the horn in the B212XL's are rated at 8 ohms. If we use the TK2050 as an integrated amplifier, won't both the woofer and the horn only receive 40w-60w of power? Hopefully I'm just missing something...

[chriscab]

Thanks for the great instructions, Dan! Last night I debuted my setup with a TA2020, 12v/8Ah SLA & Gemini RS-308, created from your wonderful instructables, at the SF Bike Party and it was definitely a success. Got some great comments from people who were impressed with the sound coming from such a compact package. No trailer or car batteries for me, everything was mounted on my rear rack. I'll post pics later. Now with this portable powerhouse, tailgating and bbq picnics will be even more of a party!

So of course, I've now gotten the bug on wanting to get louder and cleaner. I'd like to upgrade to the TK2050 with the monoXover and another SLA. My question is: To get full power from the amp with 24V, I'd still need a pre-amp to boost the signal going to the amp, correct? And if so, should it go between the source/MP3 player & x-over, or x-over & amp?

[kristoballa07]

Chriscab, did you ever get any advice on this question? I am doing a similar set-up and am also wondering where the pre-amp/mixer should go.

[tamadoctor]

I'm planning on building a stereo system. I'm looking at two of the Behringer B212XL's, two TK2050 2x100w Amps, and two crossovers. I'm also looking at an amp/mixer as you described elsewhere. The TK2050 is rated 100W at 4 ohms, however the B212XL is rated 8 ohms. So am I to assume I won't get full power out of this? Or could I instead wire one crossover into one amp, split the channels to the tweeter and woofer and run both in parallel to get full power and two mono speakers? I think I may be missing something here. Advice would be appreciated!

PS I'm digging the work you've done on your mobile DJ rigs. Thanks for posting!

[dan]

yes, if you used 1 amp you could wire both of the speakers to it but then you probably have your amp outside the speaker, a little less convenient. the sure amp will do maybe 60 or 70W with 8 ohms i think.

[User1]

"When we put the crossover before the amp, we can also use it to adjust the volumes of the tweeter and woofer, and also to combine stereo to mono if we want to. operating on the un-amplified signal these can all be done without power waste."

Hey great instructable Dan! You did a great job on laying out some very nice plans.

I'll be following on doing something like this. The only problem I had with your post was how to adjust the volume on the tweeter and woofer? Are you talking about doing that at the MP3 player? At the crossover? I didn't see any knobs on the crossover, so is it a set it and forget it system? I'm just really lost where this is suppose to be adjusted.

[dan]

the monoXover crossover has 2 knobs built in, yes. its meant to be set once to calibrate the speaker