DIY: I want to build my own components. Questions.

**nobb** · 04-20-2007, 09:07 PM

Hi.

Aftermarket components cost alot, so I figure why not try to build my own components from the bare drivers. Here are the drivers I am planning to use:

Dayton ND20FA tweeters
http://www.partsexpress.com/pe/showd...number=275-030
Audax 5.25 inch Aerogel (really good reviews on the Aerogel series)
http://www.partsexpress.com/pe/showd...number=296-155

The difficult part is designing the crossovers. I found these two sites which help do the calculations on the crossover:
http://www.apicsllc.com/apics/Misc/filter2.html#second
http://www.lalena.com/Audio/Calculator/XOver/
I will probably do a 12dB/octave crossover, but I am still undecided on the crossover type and the frequency to cross it at (4000 to 5000 hz, but not sure exactly where).

The two drivers I am using are both 6 ohm, but what would be the total impedance of the system? Do I just go 1/((1/6)+(1/6))? That would yield 3 ohms, and not the 4 that is recommended from my amp's specs.

Does anyone have any tips? Feel free to post other advice you may have.

**lbridges** · 04-20-2007, 11:58 PM

My advice would be to save a few more bucks and get someone to design the crossovers that is familiar with the set. X-over design is not as simple as just setting a frequency.

That said, the X-over splits the frequencies, so it's 6-Ohms below & 6-Ohms above - so the amp "sees" 6-Ohms across the spectrum.

You might want to give a look through Parts Express designs, they may have a good match for components and they usually provide the X-over specs needed as well.

**Dennis5587** · 04-21-2007, 02:29 AM

you could also bi-amp and go with an active crossover

**nobb** · 04-21-2007, 12:35 PM

I guess 6 ohms would be alright for my amp. Maybe just set the gains higher for the same volume. I dont really want to bi-amp, or go active because the crossover itself would cost as much as a set of drivers, plus I dont want to run the extra wiring. I will borrow some speaker building books from the library and start reading those as soon as my finals are over =)

One more quick question. The tweeters are rated at 15 watts and the 5.25 is at 40 watts. My amp can put out 60 at 4 ohms, so probably a bit less at 6 ohms. Do I risk damaging the tweeters at moderate volumes? I'm guessing the power wont be distributed 50-50 between the two drivers right? Just a little concerned because all these other tweeters I've seen are listed to be able to handle 80+ watts. I usually listen to music at moderate levels, but once in a while I like to turn it up a bit.

**symon_say** · 04-22-2007, 11:40 AM

Be careful setting your gains high, cause you can put your amp into clipping zone and damage your speakers, you dont need much power to make home and pro audio stuff louder, cause they're much more efficient, a car speakers is generali between 85-90 dB of SPL, the home and pro audio most of then start at 90dB of SPL.

For the tweets the crossover should regulate the power difference.