Help me make my first project.

[milsman2]

Fair enough. However, if am running 30+/- V to the rails and this goes to the amp powering a 4 Ohm load

http://www.national.com/ds/LM/LM3886.pdf

the amp won't like that. How do I avoid this? Isn't the amp putting out power based on the supply voltage?

 

[Francec]

Isn't the amp putting out power based on the supply voltage?

Well yes but the amp amplifies according to the gain that is set chosen values of resistors, usually around 20dB. Since the tweeter has high sensitivity compared to the woofer, the signal to it will need to be lower than that to the woofer; lower input = lower output=no problem. Remember the crossover needs to have pots to set levels.
See Rod Elliott's circuits for more information;
Linkwitz-Riley Electronic Crossover

Frank


Frank

 

[Neil Davis]

Since you are planning on using the LM3886-series of chips, you might want to look at an old design I have posted. I't got a built-in 4-pole active crossover network that you can "program" using resistor packs, and the layout is designed to connect to a heatsink to make a "smart plate amp". All of the source files are posted, so you can modify the schematics and quickly update the PCB's to meet any new requirements. The layout is very quiet, with separate ground runs to a common point. PCBExpress is free, so you can take this proven design, adapt it to your needs, and take credit for the modifications.

It is Circuit #1 at this location: Neil’s DIY Plate Amp Page

 

[milsman2]

Ah that makes a lot of sense. I have been learning a lot these past few days. I think I have settled on using

http://www.parts-express.com/pdf/264-834s.pdf and

http://www.parts-express.com/pdf/264-850s.pdf

I last posted and will have the setup be

Analog In -> miniDSP-> LM 3886 Gain Clone -> Driver

There will be a seperate PSU for the woofers and the tweeters, respectively. Sound like a plan?

 

[Francec]

Yes, a good plan that now needs some action to realise the benefits of DIY!

 

[Tytte71]

Hi - you really are a lucky guy who have access to such competence and tools at the university
Regarding your project, I will recommend you to take a look at the Seas DXT dome SEAS Prestige 27TBCD/GB-DXT (H1499) Tweeter: Madisound Speaker Store. Although expensive compared to the TB, the benefit of this Seas driver is worth every penny. The MiniDSP easily corrects for the curved frequency response. You will have a very beautiful sounding and versatile tweeter - There are high-end manufacturers using it and with very good reasons... like this http://www.abrahamsenaudio.com/images/fs401/
I would also concider using a 6 1/2" driver or in anyway a driver with larger xmax than the proposed TB (unless you want to cross over with a sub). There also seems to be an issue with the TB driver looking due to ragged impedanse curve.
Cheers