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-   -   A cheap pair of mtms using goldwood 8's? (http://www.diyaudio.com/forums/multi-way/105900-cheap-pair-mtms-using-goldwood-8s.html)

saabracer23 26th July 2007 04:32 PM

A cheap pair of mtms using goldwood 8's?
 
Hello all, my brother has asked me to build him a pair of speakers for as cheap as possible. Seeing as he is not an audiophile by any means (being nice I gave him a pair of 50 dollar rca cables and he cut off the ends and used them as speaker wire because they looked cool) I am going to use drivers I have lying around. So I'll charge him for the wood and crossover components. Right now he has a pair of optimus pro 77s and for low end a pair of tangband 6-1/2 neo subs. He wants something that will fill the air more.

So here is my idea: I have four Goldwood 8" Heavy Duty drivers or whatever they call them. I can't get PE to load but they have them for like 25 bucks a piece, they have a rubber surround, cast frame, poly cone, 3 mm xmax :bigeyes: lol


For the tweeters I have a pair of infinity polycells (foam dome) and a pair of kef from the k160 bookshelf speakers. I need your help on picking which tweeter to use.

I don't want to buy new drivers because I could probably run the 8 FR and put a cap on the tweeters and he would be as happy as a clam.

So I was wondering if I could get help on the tweeter selection and possible help on a SIMPLE crossover, nothing to indepth considering my driver selection. I know this is going to be kinda hard with no specs but PE has them for the woofers but i don't know where to find them for the tweeters.

Thank you in advance for any help

Dan

sdclc126 27th July 2007 02:14 AM

I will hazard a guess here that the KEF tweeters are probably superior to the Infinitys, but since you have both you can try the build with both and go with whatever your brother prefers.

I don't see any technical data on the Goldwood woofers, but since their claimed frequency response goes up to 7 kHz they might be able to be used as midwoofers in your build. 8" is usually the extreme upper end for a 2-way design, but since this is a pretty basic project there's no harm in trying.

One caveat - if your brother plans to "crank" these speakers there is a chance of tweeter damage with just capacitors as crossovers, so I would suggest either a second order crossover for them, or a fairly high XO point, or both.

Do the basic build first - probably a simple TMM layout - you can always modify it later as your budget allows.

mashaffer 27th July 2007 03:12 AM

I pretty well agree with SD. Try the two different tweets and see what you think. The woofers are actually kind of interesting. Are they the 8 or 4 ohm version? For the sake of discussion I will assume the 8 ohm version. A quick sim indicates an acceptably small box for sealed or BR. Sealed gets you down to about 60 Hz while BR will get below 40.

Given that we are not dealing with an audiophile here you could (based on the graphs given at PE) use the woof up to about 5KHz with a crossover designed to reduce the big bump from 3-5K (just put f3 down lower than the f3 point on the tweeter). This way a simpler crossover can be used on the tweeter without fear since you would be crossing well up into its useful range.

If he likes to really rock out you might want to try a 2.5 way setup (since you have four woofers). You could even get fancy (for very little money) and make the main mid woofer in a sealed sub enclosure of about 0.5 ft^3 and the lower woofer in a vented sub enclosure of about 1.5 ft^3 and let it supplement the mid woof below 80 Hz. It could be a really fun experiment.

And to have even more fun you could put the best sounding tweeters in the front panel and put the poorer of the two firing to the rear with an L-pad to use as an ambiance control.

So many drivers... so little time. ;)

mike

saabracer23 28th July 2007 04:39 PM

Thanks for the input guys, I actually got a pair of goldwood tweeters. Well plans may have changed (as they always do), my brother bought a pair of 12" 3 way cerwin vegas that he wants me to fix. The woofers need resurrounded. But I don't know what he wants, I let you guys know.

Thanks again for you time
Dan


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