Hi Vix,
Do make sure that the T-bass circuit is connected directly to the amplifier, and not after a crossover section. T-bass needs very low impedance drive.
So how does the cork sound compared to other phase plugs.
Possibly a little less strident ?
My impressions is that the cork needs to be sanded for a rounded or asymmetrical leading edge. There is a symmetrical central launch plane about 1" in diameter which could introduce a diffraction notch and peak at higher frequencies.
Cheers ......... Graham.
Do make sure that the T-bass circuit is connected directly to the amplifier, and not after a crossover section. T-bass needs very low impedance drive.
So how does the cork sound compared to other phase plugs.
Possibly a little less strident ?
My impressions is that the cork needs to be sanded for a rounded or asymmetrical leading edge. There is a symmetrical central launch plane about 1" in diameter which could introduce a diffraction notch and peak at higher frequencies.
Cheers ......... Graham.
Graham Maynard said:
Hi Graham,
Once again, thank you very much for the T-bass!
Yes, it is connected directly after the amplifier (OK, not immediately, but via thick cables) , and then comes an inductor (for 1-st order low pass) and a boucherot.
Cork phase plug does not sound bad, but there is still some slight fuzziness to the sound. I may get more such plugs and try to shape them and see what happens.
Regards,
Vix
Hi Vix, probably not. For bass boost I am just using a Blaxandal tone control in the preamp.
I'd be interested in any more comments regarding the subjective effects of phase plugs in the B200 as i have tried to convince myself that the main problem with the B200 is the rising response starting at about 1 KHz, this to me is why the bass is weak sounding. I have not seen any freq response graphs of the B200 with and without a phase plug, but maybe someone else has ?
cheers.
I'd be interested in any more comments regarding the subjective effects of phase plugs in the B200 as i have tried to convince myself that the main problem with the B200 is the rising response starting at about 1 KHz, this to me is why the bass is weak sounding. I have not seen any freq response graphs of the B200 with and without a phase plug, but maybe someone else has ?
cheers.
I have not been working at the LS for some time now, but the best sound I have had from any LS to date came from my B200 with felt/foam on the pole face, plus foam fingers, plus a paper cone replacing the dust cap.
http://server6.theimagehosting.com/image.php?img=Spirit.2.jpg&album=0&fullsize=1
This cone is superglued to the forward edge of the voice coil former and is 65mm from former to tip and corrects for the acoustic centre receding with frequency.
Cheers ............ Graham.
(I know this is not audio but it is an interesting read, and the links below it are real world apparatus. The audio amp needs to be about 1.5kW. to provide that continuous 15A sine.)
http://www.cancer-cure-that-worked.com/rife-cancer-trials-san-diego-bx-by-virus.htm
http://uk.youtube.com/watch?v=xTafaQuk_EY&feature=channel_page
http://uk.youtube.com/watch?v=x9_jltdOEws
http://server6.theimagehosting.com/image.php?img=Spirit.2.jpg&album=0&fullsize=1
This cone is superglued to the forward edge of the voice coil former and is 65mm from former to tip and corrects for the acoustic centre receding with frequency.
Cheers ............ Graham.
(I know this is not audio but it is an interesting read, and the links below it are real world apparatus. The audio amp needs to be about 1.5kW. to provide that continuous 15A sine.)
http://www.cancer-cure-that-worked.com/rife-cancer-trials-san-diego-bx-by-virus.htm
http://uk.youtube.com/watch?v=xTafaQuk_EY&feature=channel_page
http://uk.youtube.com/watch?v=x9_jltdOEws
Help needed with x over
Dear all
I am quite new to speaker building, some time ago I decided to built an OB based on Visaton design, simply changed the BGS for Eminence.
Could any one help me on the x over. I need some schematics on the best implementation for this desing. I have not any measurment systems nor experience with simulation software.
Please HELP!
Thanks
Dear all
I am quite new to speaker building, some time ago I decided to built an OB based on Visaton design, simply changed the BGS for Eminence.
Could any one help me on the x over. I need some schematics on the best implementation for this desing. I have not any measurment systems nor experience with simulation software.
Please HELP!
Thanks
Hi,
As you could probably read, I had also started an OB design based on Visaton design. My initial ideas was " just to change the BGS for Eminence" but it didn't work as expected. In the meantime, bit by bit, it changed so much that the only common thing with that design is the fullrange driver itself, Visaton B200.
To summarize, the basic baffle remained the same. No side wings meant a metal "L" support was added, and it also meant a completely different crossover. I am using a DIY active crossover. After a lot of experimentation, I had settled for those crossover points:
1. Visaton B200: 350 Hz high-pass, 2nd order, Q=0.5
2. Eminence Beta 15: 80 Hz low pass, 2nd order Q=0.5
had later added a passive T-bass circuit between bass amplifier and Eminence driver:
http://www.diyaudio.com/forums/full-range/130679-t-bass-drive-ob-lf-drivers.html
So, in the configuration you have, I wholeheartedly recommend you not to waste your time with passive crossovers. Get one more amplifier and an active crossover. Either build it, or buy something like Behringer or if you can afford, purchase Nelson Pass B5 crossover circuit, made specifically for open baffles.
Edit:
p.s. Visaton B200 is modified with dustcap cut and phase-plugs installed. If your driver is not modified, you may find that you need a notch circuit, either active, like here:
http://www.diyaudio.com/forums/full-range/99662-visaton-b200-taming-shout.html
Or passively with 0.6-1 mH inductor in parrallel with 6-15 ohm resistor (adjust to taste).
As you could probably read, I had also started an OB design based on Visaton design. My initial ideas was " just to change the BGS for Eminence" but it didn't work as expected. In the meantime, bit by bit, it changed so much that the only common thing with that design is the fullrange driver itself, Visaton B200.
To summarize, the basic baffle remained the same. No side wings meant a metal "L" support was added, and it also meant a completely different crossover. I am using a DIY active crossover. After a lot of experimentation, I had settled for those crossover points:
1. Visaton B200: 350 Hz high-pass, 2nd order, Q=0.5
2. Eminence Beta 15: 80 Hz low pass, 2nd order Q=0.5
had later added a passive T-bass circuit between bass amplifier and Eminence driver:
http://www.diyaudio.com/forums/full-range/130679-t-bass-drive-ob-lf-drivers.html
So, in the configuration you have, I wholeheartedly recommend you not to waste your time with passive crossovers. Get one more amplifier and an active crossover. Either build it, or buy something like Behringer or if you can afford, purchase Nelson Pass B5 crossover circuit, made specifically for open baffles.
Edit:
p.s. Visaton B200 is modified with dustcap cut and phase-plugs installed. If your driver is not modified, you may find that you need a notch circuit, either active, like here:
http://www.diyaudio.com/forums/full-range/99662-visaton-b200-taming-shout.html
Or passively with 0.6-1 mH inductor in parrallel with 6-15 ohm resistor (adjust to taste).
Last edited:
I will second Vix's recommendations on active, low X-over, and phase plugs.
Active X-over - I find this easier and cheaper then passive line-level Xovers, unless you use expensive amps. I use class D.
Phase plugs - End of a broomstick, sanded down.
Eminence Alpha 15s - If you want bass at higher volumes......
OB B200/Eminence Alpha 15
Active X-over - I find this easier and cheaper then passive line-level Xovers, unless you use expensive amps. I use class D.
Phase plugs - End of a broomstick, sanded down.
Eminence Alpha 15s - If you want bass at higher volumes......
OB B200/Eminence Alpha 15
Oops, I meant to say I found passive line level Xovers to be easier and more cost effective than speaker level crossovers.
It may be worth considering getting the measuring gear and try the MiniDSP boards. The Behringer route comes with a number of headaches and things have moved on. Try the following links;
Gainphile: Measuring Open Baffle loudspeakers
Gainphile: Cheap and accurate speaker measurement
Getting Started with FuzzMeasure Pro
http://www.minidsp.com/applications/auto-eq-with-rew
Last edited:
Wow...today I was fiddling with Open Baffle again..and I just saw that this thread is four years old!
So, the latest thing I tried was to make a 'quick and dirty' version of "Slot Loaded Open Baffle" something which is about exploring the effects that Nelson Pass described here:
The Slot Loaded Open Baffle Project Article By Nelson Pass
Since it's quite late over here, I can't play them loud, so more about impressions tomorrow. Since the baffles are as ugly as they can get, I will not post the pics in the OB gallery. For the ones who want to see the mess I made today, here they are:
So, the latest thing I tried was to make a 'quick and dirty' version of "Slot Loaded Open Baffle" something which is about exploring the effects that Nelson Pass described here:
The Slot Loaded Open Baffle Project Article By Nelson Pass
Since it's quite late over here, I can't play them loud, so more about impressions tomorrow. Since the baffles are as ugly as they can get, I will not post the pics in the OB gallery. For the ones who want to see the mess I made today, here they are:
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