Those telefunkens are very similar to the Isophons I run in an open baffle. Indeed they do sound fantastic all by themselves. Be careful as they are really sensitive and should play loud with less than 5watts of power - don't blow them with your monster amp.
Start with the tweeter, I advice getting a pair of the Isophon HM10's which can be had for about $35 off ebay. I am using a series cap of 0.8uf for crossover - no padding necessary and they will be rolled in at around 10khz. Try different cap values until it sounds right. You may need to experiment with series padding resistors (1-4ohm to start with) but this will alter the crossover frequency so its a matter of trial and error till you get it right.
The bass is a little more complex since you need an inductor to do the crossover and it difficult to know the appropriate value until you start experimenting - and they are expensive. I advice looking into aperiodic loading (leaking sealed box) for the bass bin as it avoids the need for a pair of 12-15 inch bass drivers per baffle which is what it takes to run them open baffle.
Shoog
Start with the tweeter, I advice getting a pair of the Isophon HM10's which can be had for about $35 off ebay. I am using a series cap of 0.8uf for crossover - no padding necessary and they will be rolled in at around 10khz. Try different cap values until it sounds right. You may need to experiment with series padding resistors (1-4ohm to start with) but this will alter the crossover frequency so its a matter of trial and error till you get it right.
The bass is a little more complex since you need an inductor to do the crossover and it difficult to know the appropriate value until you start experimenting - and they are expensive. I advice looking into aperiodic loading (leaking sealed box) for the bass bin as it avoids the need for a pair of 12-15 inch bass drivers per baffle which is what it takes to run them open baffle.
Shoog
This might or might not be a worthwhile observation. Has anyone ever tried a guitar amp driver as an open baffle driver? I mean every guitar amp I ever seen has an open back cabinet doesn't it?
Shoog thanx so much . My First question is how to cut off the bass just for now so i can listen as i build... and just one more question I saw some place that the baffle should be a little less than twice the diameter of the given driver ? I first had these in a 48"x48" baffle and thought they sounded nice Then I ripped the plywood and made "folded baffles" for better imaging but i guess the loss of bass over came that idea. Scott
Hello, search for Tone Tubby. Lots of info on it's use for OB, and high praises all over the different audio sites.
Any driver can be used in OB and gives good result. The best result is obtained by the best implementation.
Maybe there'd be pure luck, but no short cut to the real excellence.
Maybe there'd be pure luck, but no short cut to the real excellence.
Try starting with a pair of recovered inductors from a sealed box speaker. Simply place it in series with the woofer and then this speaker inductor combination in parallel with the main driver. Should get you started.
My baffles are about just less than twice the driver width. There is an exact calculation to work out the cut off frequency of the baffle depends on the baffle width. Do a search for an OB calculator in google, 18" works out at about 400hz, which means the woofer should be rolled in at about 300hz to avoid a bass hump where the main driver and woofer meet.
I use a dedicated subwoofer amp of my own design with built in crossover equalizer.
shoog
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