murphy, I think Dave's reply above is in response to both henry's suggestion of OB woofers, and your search for more/ deeper LF response than the Fonken127 is delivering.
Active in this case refers to separately/directly powered woofer(s), and we've certainly found that multiple smaller woofers have many advantages - there are more than a few methods to achieve this.
We did in fact build a woofer a couple of years ago for exactly such an application. It was designed to both house a pair of small woofers as well as act as a stand for the Fonken cabinets. As we happened to have lots of them on hand, we elected for a pair of CSS SDX7s per side, but any appropriately sized driver ( i.e. fits an enclosure of approximately the same footprint) would suffice. With line level filters and separate power amp with level controls for woofers, issues of driver sensitivities that can be a major PITA with passive high power XOs are essentially eliminated.
what is exactly the advantage to go for a active woofer/sub?
How powerful do the amp need to be? I have a realistic sta-2080 with 100 wpc and im wondering if it would do the job
@dave: how good do the sub sounded? Is it hard to make and what drivers are used? Any other suggestion for a sub.
thanks
How powerful do the amp need to be? I have a realistic sta-2080 with 100 wpc and im wondering if it would do the job
@dave: how good do the sub sounded? Is it hard to make and what drivers are used? Any other suggestion for a sub.
thanks
Active gives much more versatility. A separate amp means the high frequency amp doesn't have to work as hard (so it sounds better. Separate woofer means FR doesn't have to do bass so it gets even better in the mids & the top. No passive components between the amps & the speakers. Seperate woofer capable of doing bass means the system does bass.
Yes, your reaslistic could be a good amp as a place to start. RS stuff was often made by very reputable OEMs.
Bud Purvine now has those woofers. Bud still thinks they are one of the best bass systems he has heard. I liked them too, but i always felt i could make them better. They use 2 SDX7eN each side.
Thet aren't really subs. Most subs don't really go high enuff to mate well with most FRs. There are lots of really good mid-woofers that could play the same role.
dave
Yes, your reaslistic could be a good amp as a place to start. RS stuff was often made by very reputable OEMs.
Bud Purvine now has those woofers. Bud still thinks they are one of the best bass systems he has heard. I liked them too, but i always felt i could make them better. They use 2 SDX7eN each side.
Thet aren't really subs. Most subs don't really go high enuff to mate well with most FRs. There are lots of really good mid-woofers that could play the same role.
dave
How much power?
someplace, a long, long time ago...
depending on the crossover frequency (somewhat) the acoustic power ratio for the top end vs. bottom end is something in the order of 10:1. A full range driver, being driven from 200 Hz up (as an example only) with 5 watts, would need at least 50 Watts to handle bass and provide enough headroom for transients as a minimum.
I know this sounds a little lame, but think of the power required to move a woofer cone with say a mass of 21.9 grams each for the SDX7 woofers and a sensitivity of 85dB@1W@1m, vs, (for the FE127) 91dB and 2.9 grams. The mass is roughly 7.5X's for the woofer vs the fullrange. Right away it is apparent that more power is required by the woofer just to move it without taking into account any electrical considerations. I am assuming a single woofer per side in this example.
Remember for power, doubling the power results in only 3dB of field gain. So if 6 dB is required for the bass driver, the power needed is 20*log(6dB/3dB) = 6X's that of the fullrange driver, if a proper balance is desired.
Now bring into consideration both of the above and you end up with something in the order of 13.5X's, as logarithms to the same base can simply be added.
(Again, Dave correct me if I am wrong). Assuming you feed 7 W to each of your fullrangers, the bass drivers will need something in the order of 94.5 W each. We now see why a lot of power is requird to produce balanced bass, without equalization or Zobel networks, etc. If passive components are used for the cross-overs, then approximately 1/2 of the energy provided to the crossover is output as heat. So now your 100 watt per channel amp is effectively a 50W/ch amp. That's the real benefit of using active (elecronic) cross-overs and bi-amplification in my opinion---you get to output the power without the power losses, and have finer control of the balance based on frequency and amplitude of the signal sent to each driver.
Sorry for the rant.
someplace, a long, long time ago...
depending on the crossover frequency (somewhat) the acoustic power ratio for the top end vs. bottom end is something in the order of 10:1. A full range driver, being driven from 200 Hz up (as an example only) with 5 watts, would need at least 50 Watts to handle bass and provide enough headroom for transients as a minimum.
I know this sounds a little lame, but think of the power required to move a woofer cone with say a mass of 21.9 grams each for the SDX7 woofers and a sensitivity of 85dB@1W@1m, vs, (for the FE127) 91dB and 2.9 grams. The mass is roughly 7.5X's for the woofer vs the fullrange. Right away it is apparent that more power is required by the woofer just to move it without taking into account any electrical considerations. I am assuming a single woofer per side in this example.
Remember for power, doubling the power results in only 3dB of field gain. So if 6 dB is required for the bass driver, the power needed is 20*log(6dB/3dB) = 6X's that of the fullrange driver, if a proper balance is desired.
Now bring into consideration both of the above and you end up with something in the order of 13.5X's, as logarithms to the same base can simply be added.
(Again, Dave correct me if I am wrong). Assuming you feed 7 W to each of your fullrangers, the bass drivers will need something in the order of 94.5 W each. We now see why a lot of power is requird to produce balanced bass, without equalization or Zobel networks, etc. If passive components are used for the cross-overs, then approximately 1/2 of the energy provided to the crossover is output as heat. So now your 100 watt per channel amp is effectively a 50W/ch amp. That's the real benefit of using active (elecronic) cross-overs and bi-amplification in my opinion---you get to output the power without the power losses, and have finer control of the balance based on frequency and amplitude of the signal sent to each driver.
Sorry for the rant.
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In the pictures of the Fonkens with the FonkenWoofs in post 22?
Those are actually unfinished BB with MDF "accents". The Fonken may have a coat of laquer, they have been veneered since.
dave
Dave,
The FonkenWoofs look good. few questions come to mind:
1. Would the FonkenWoof plans be with you?
2. Can we plan something similar with with 2 x EL166/side?
3. Can they be used as helper woof boxes for other FR systems in the room? A bit like your room where there are quite a few pairs all the time. If required can cross low for better integration.
-Zia
The FonkenWoofs look good. few questions come to mind:
1. Would the FonkenWoof plans be with you?
2. Can we plan something similar with with 2 x EL166/side?
3. Can they be used as helper woof boxes for other FR systems in the room? A bit like your room where there are quite a few pairs all the time. If required can cross low for better integration.
-Zia
Yes. It really is more a concept than a design that ever got finished. That the SDX7 work in a small box is what helps keeps it relativily small (as pictured they are ~28 litres net). These are a TL stuffed till aperiodic (because of the XBL tendency to "fart" i had to plug them up). Next one will be sealed (or intentionally aperiodic). To allow them to XO higher i was using them with woofers at the top in the end and that is how Bud uses them.
Yes, you'd need to start from scratch, keeping an appropriate form factor.
Yes. Bud has been useing them with his Bamboo Fonken, but did use them with dMar-Ken7 (before he had to ship them to Canada Post in Ottawa (anyone in Ottawa keep an eye out for CP insurance auctions), and will again when he gets his replacements.
For aesthetics you would want to shape them to fit the footprint of what sits on top.
dave
Yes, you'd need to start from scratch, keeping an appropriate form factor.
Yes. Bud has been useing them with his Bamboo Fonken, but did use them with dMar-Ken7 (before he had to ship them to Canada Post in Ottawa (anyone in Ottawa keep an eye out for CP insurance auctions), and will again when he gets his replacements.
For aesthetics you would want to shape them to fit the footprint of what sits on top.
dave
In building speakers with Fostex drivers, one thing i have no idea how to do is the countersink of the driver. That odd almost-squarish profile of the basket, how do you route a countersink precisely? I always see a very nice, clean countersink for them in your speakers.
Can you achieve that without a CNC? Is there a trick to it?
You're making me thinking of building Fonkenwoofs for my 167, And maybe a Fonken enclosure for them as well (currently in a Fostex BR enclosure)! 😀.
Can you achieve that without a CNC? Is there a trick to it?
You're making me thinking of building Fonkenwoofs for my 167, And maybe a Fonken enclosure for them as well (currently in a Fostex BR enclosure)! 😀.
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We usually do it with a CNC, It can be done by making a router guide (that is how Bernie is doing it). And, in my past when i was allowed to make speakers, i could do a pretty good job freehand (has to be taken slow & carefully, and is way easier if you have a small low power router). Probably easiest to do by flush mounting and then scabbing on an extra layer just the right thinkness. Then you can use a jigsaw and some files. Or if you use cork, a razor knife.
dave
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