Design Check!

[saggybob]

Hi all,

trying my hand at building a 41Hz amp6 in a small portable enclosure of about 30L (yes its more or less a boombox) and just hoping some of you could give it a quick skim to make sure everything is looking right before i go building and blowing up things.

Drivers i plan on using are:

2x Eminence Alpha 8A
http://www.parts-express.com/pdf/290-401s.pdf
and
2x 1" Peerless tweeters
http://www.parts-express.com/pdf/264-1028s.pdf

and with a 2nd order crossover at 2500Hz



Few questions i still have are:
1) This seems to me to be a good driver/tweeter match, anyone disagree?
2) with a 4 ohm tweeter should i add a 4ohm resistor in parrallel? before or after the crossover?
3) any improvements/suggestion/advice you can give before i build?!!

appreciate it guys,

Louis


EDIT: little diagram i made.....

[DougL]

2) with a 4 ohm tweeter should i add a 4ohm resistor in parrallel? before or after the crossover?

No.

[CCU]

Originally Posted by DougL

No.

That would lower the totalt ohms resistance to 2ohm.. that would be bad the the amp and use unnecessary power for heating the resistor

[wintermute]

Hi Louis,

1. I would tend to disagree with point 1 mainly because to avoid beaming you would need to crossover at a low freq (around 1700Hz or lower) for an 8" driver and that tweeter will not be happy being crossed that low. Beaming my not be an issue in a boombox though

2 no as already stated! you can run a mix of 8 ohm and 4 ohm drivers in a speaker, you just need to design the crossover for the correct impedance of each driver. The tweeter doesn't say whether it's sensitivity is 1W/1M or 2.83V/1M so it is hard to tell whether any level differences might cause an issue that needs padding of one or other of the drivers.

3. Your proposed crossover looks like a standard 2nd order crossover. With the rising frequency response on the woofer and especially the peak after 3Khz you might need something a little more complex than that. If you have gone with a textbook design you might want to start reading up on why text book crossovers are a bad idea

Note that the freq response curve on the woofer does not state what the configuration was when the measurement was done so it is hard to make any informed comment about it. when put into your own cabinet the curve will undoubtedly look different anyway

Tony.