Hi Bob,
This whole crossover with its versatility sounds like what I could use for my multi-driver OB with sealed sub scheme.
Forgive my laziness of not wanting to seach through 50+ pages of post. Would you please direct me to the latest information about this board and needed components?
I feel I will be interested in 2 to 4 of these boards. But, I would like to know the price per item to include shipping in the US?
Also, when you would expect another group buy to materialize?
Thanks
Norris
This whole crossover with its versatility sounds like what I could use for my multi-driver OB with sealed sub scheme.
Forgive my laziness of not wanting to seach through 50+ pages of post. Would you please direct me to the latest information about this board and needed components?
I feel I will be interested in 2 to 4 of these boards. But, I would like to know the price per item to include shipping in the US?
Also, when you would expect another group buy to materialize?
Thanks
Norris
Norris,
Click on my www button and you'll see a page for the AF4 with a user guide, schematics, board layout and excel spreadsheet for calculating component values.
I don't expect to be able to run another group buy anytime soon. I just started a new job that is all consuming. I believe Jens will make the gerber files are available if someone wants to run another buy.
Click on my www button and you'll see a page for the AF4 with a user guide, schematics, board layout and excel spreadsheet for calculating component values.
I don't expect to be able to run another group buy anytime soon. I just started a new job that is all consuming. I believe Jens will make the gerber files are available if someone wants to run another buy.
I want to thank you Bob, and Jen Rasmussen for all of the time and effort that both of you expended on this filter board and information.
It is obvious that was allot of time. And it took some knowledge to design such a versatile filter.
This active filter will work quite nicely for my needs.
I saw your reference about the F-14 Tomcat fighter bomber on your website. I assume that you may have been a pilot, since there was an in flight picture displayed from the cockpit.
I am a civilian and have had limited exposure to this airplane, only at air shows. But, it was very impressive when it flew down the run way upside down. Then, the pilot inversed the planes positon, kicked in the after burners, and went straight up into a steep climb. This was done from the runway pass over speed that I figure was close to 200 MPH, to what ever speed it took to fly several hundred feet straight into the air.
Now, that is impressive, especially for the size and weight of this aircraft.
I am glad that you were able to experience these airplanes first hand, it had to be exciting. Thanks for your service.
Jimbo 1968 has made an offer to sell me the AF4 boards that I need, thanks. Jim, I have sent you a reply to your email requesting 6 boards if you have them.
Bob, good luck with your new job.
Norris
It is obvious that was allot of time. And it took some knowledge to design such a versatile filter.
This active filter will work quite nicely for my needs.
I saw your reference about the F-14 Tomcat fighter bomber on your website. I assume that you may have been a pilot, since there was an in flight picture displayed from the cockpit.
I am a civilian and have had limited exposure to this airplane, only at air shows. But, it was very impressive when it flew down the run way upside down. Then, the pilot inversed the planes positon, kicked in the after burners, and went straight up into a steep climb. This was done from the runway pass over speed that I figure was close to 200 MPH, to what ever speed it took to fly several hundred feet straight into the air.
Now, that is impressive, especially for the size and weight of this aircraft.
I am glad that you were able to experience these airplanes first hand, it had to be exciting. Thanks for your service.
Jimbo 1968 has made an offer to sell me the AF4 boards that I need, thanks. Jim, I have sent you a reply to your email requesting 6 boards if you have them.
Bob, good luck with your new job.
Norris
Norris,
I was a RIO (Radar Intercept Officer), like Goose in Top Gun. Lots of ways to have fun, and even more ways to buy the farm. If the inverted pass you saw was with the landing gear in the wind, it was probably close to 250 knots (~300 mph), which is the maximum allowed speed with the gear extended. (A friend found out that the aircraft will do close to 500 knots gear down, but not without damage to the gear. Oops!
)
The high speed passes you saw were probably 500-550 knots (~600-650 mph). We'd shoot for Mach .9-.95. Out at sea when we didn't have to worry about breaking windows we'd do shows for foreign dignitaries with a fly by at 75 feet running mach 1.2 (around 900 mph), pull 7Gs into the vertical and still have 600 knots or more at 15,000 feet, pull 7Gs again and scramble to join the large formation fly-by. Looking back, it's hard to believe I got so used to those speeds that 5-600 mph felt fairly slow.
The new job is a lot of work, but the work/reward ratio is high, both professionally and financially. Last week was part time - only 58 hours. Thanks for you good wishes.
DIY Audio content: The heat sinks are in, I'm going to start packing orders tonight.
I was a RIO (Radar Intercept Officer), like Goose in Top Gun. Lots of ways to have fun, and even more ways to buy the farm. If the inverted pass you saw was with the landing gear in the wind, it was probably close to 250 knots (~300 mph), which is the maximum allowed speed with the gear extended. (A friend found out that the aircraft will do close to 500 knots gear down, but not without damage to the gear. Oops!
)The high speed passes you saw were probably 500-550 knots (~600-650 mph). We'd shoot for Mach .9-.95. Out at sea when we didn't have to worry about breaking windows we'd do shows for foreign dignitaries with a fly by at 75 feet running mach 1.2 (around 900 mph), pull 7Gs into the vertical and still have 600 knots or more at 15,000 feet, pull 7Gs again and scramble to join the large formation fly-by. Looking back, it's hard to believe I got so used to those speeds that 5-600 mph felt fairly slow.
The new job is a lot of work, but the work/reward ratio is high, both professionally and financially. Last week was part time - only 58 hours. Thanks for you good wishes.
DIY Audio content: The heat sinks are in, I'm going to start packing orders tonight.
Thanks Bob for the detailed description of the fly by.
The fly by that I experienced was about 75 feet above the landing strip. I did not realize that they were cruising that fast.
It was great when you could first see them coming inverted for this fly by.
Then they were gone in a flash with no sound to be detected until they were upright and on their way straight upward.
Cool!
You must of had a great time in the cockpit. Someplace that I can only dream of being. But, at 50 years old, and out of shape. I can imagine the G forces working against me. Its only a dream.
Thanks for sharing this enthusiastic experience with me. I even got a little pumped up.
Norris
The fly by that I experienced was about 75 feet above the landing strip. I did not realize that they were cruising that fast.
It was great when you could first see them coming inverted for this fly by.
Then they were gone in a flash with no sound to be detected until they were upright and on their way straight upward.
Cool!
You must of had a great time in the cockpit. Someplace that I can only dream of being. But, at 50 years old, and out of shape. I can imagine the G forces working against me. Its only a dream.
Thanks for sharing this enthusiastic experience with me. I even got a little pumped up.
Norris
I'm trying to understand all this, and I think I've got it. I'm attaching a model of my rather special speaker again (this is the left one), with a front mounted woofer as suggested by Bob.
What I know so far is to use the input buffer, 12 dB high- and lowpass filters, and output buffer (is the output buffer really necessary?). I'll put the filters at 250 Hz like the original passive crossovers. I'll also use a notch for the bass, after measuring frequency response. All opamps are the new LM4562. What I haven't decided on, or quite understood yet, is whether to use allpass and LR.
Due to the recessed mid/tweeter baffle, their voice coils are vertically aligned with the woofer VC. My ear height is about 25 cm below the tweeters, at the focal point of the mids' inward slant, and about 50 cm above the woofer. Should I even bother playing around with an allpass on this? If all it does is compensate for different distances to the voice coils, I can do that by moving the mid/tweeter baffle back or forward a bit more before I start cutting wood.
LR: Considering I'm using a notch filter, will this do me any more good than add bottom end bass? The woofer is a 10" Seas 1305 in a 50 liter vented box. I've got plenty of power to drive it.
What I know so far is to use the input buffer, 12 dB high- and lowpass filters, and output buffer (is the output buffer really necessary?). I'll put the filters at 250 Hz like the original passive crossovers. I'll also use a notch for the bass, after measuring frequency response. All opamps are the new LM4562. What I haven't decided on, or quite understood yet, is whether to use allpass and LR.
Due to the recessed mid/tweeter baffle, their voice coils are vertically aligned with the woofer VC. My ear height is about 25 cm below the tweeters, at the focal point of the mids' inward slant, and about 50 cm above the woofer. Should I even bother playing around with an allpass on this? If all it does is compensate for different distances to the voice coils, I can do that by moving the mid/tweeter baffle back or forward a bit more before I start cutting wood.
LR: Considering I'm using a notch filter, will this do me any more good than add bottom end bass? The woofer is a 10" Seas 1305 in a 50 liter vented box. I've got plenty of power to drive it.
Attachments
Ideally you'll want to use the all pass to compensate both for the acoustic center (not necessarily the voice coil) offset AND phase differences at the crossover point. You can measure the drivers and crossover individually and see if there is enough phase difference to worry about.
Output buffers are not absolutely necessary. If you are not using the gain control you will get a buffered output from the filter. The buffer provides a low impedance source to drive your amps. If the interconnects are short and you don't use the attenuator you shouldn't have an issue. Otherwise you might find that your system is overly sensitive to cable choices.
You can use a notch filter to tame upper end breakups. The Linkwitz transform can extend the low end response if your woofers have the excursion and power handling to take it. If the woofers aren't up to it, you either limit your system output or live with lots of distortion. You might consider a high pass on your woofer to prevent damage below the port tuning frequency.
Output buffers are not absolutely necessary. If you are not using the gain control you will get a buffered output from the filter. The buffer provides a low impedance source to drive your amps. If the interconnects are short and you don't use the attenuator you shouldn't have an issue. Otherwise you might find that your system is overly sensitive to cable choices.
You can use a notch filter to tame upper end breakups. The Linkwitz transform can extend the low end response if your woofers have the excursion and power handling to take it. If the woofers aren't up to it, you either limit your system output or live with lots of distortion. You might consider a high pass on your woofer to prevent damage below the port tuning frequency.
Member
Joined 2004
The eagle has landed...
Hello Bob: The filter boards arrived today and I would like to thank you and all those involved in this effort.I estimate these boards will save me at least 2 weeks worth of P to P wiring 🙂
FYI-I would be interested in a group buy of" Bob’s Crazy Good Cookies" posted on your website!!....
Thanks again
Bob C.
Hello Bob: The filter boards arrived today and I would like to thank you and all those involved in this effort.I estimate these boards will save me at least 2 weeks worth of P to P wiring 🙂
FYI-I would be interested in a group buy of" Bob’s Crazy Good Cookies" posted on your website!!....
Thanks again
Bob C.
My boards would have arrived today too, but customs had to butt in and process it, so I won't have it in my hands 'till over newyears... And it doesn't come cheap, either. D*** customs...
Re: The eagle has landed...
I have been meaning to try these out this holiday season, but haven't gotten around to it. Paying Bob to do the dirty work is DEFINITELY option #1! 😀😀😀
I second the motion!RCBandwidth said:
I have been meaning to try these out this holiday season, but haven't gotten around to it. Paying Bob to do the dirty work is DEFINITELY option #1! 😀😀😀
Yes, all shipped, but yours may take a few days longer as it had to go airmail. Argentina does not accept USPS Global Priority Mail.
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