Filter for Abbey's and Fostex FE166
I could bet I have seen those filters somewhere here, but the search didn't show anything.
Anybody remember where it is, or knows what those filters should look like ?
I should maybe note that this is for a regular voltage source amp of about 30W class A single ended
Cheers
Magura
I could bet I have seen those filters somewhere here, but the search didn't show anything.
Anybody remember where it is, or knows what those filters should look like ?
I should maybe note that this is for a regular voltage source amp of about 30W class A single ended
Cheers
Magura
I think you're talking about baffle-step compensation. God help us, Terry Cain, may he rest in peace, would have a fit if he knew.
The purpose of BSC is not to take 'bumps' out of the response, but to compensate for baffle-step diffraction (a frequency determined by baffle-width, where the speaker stops projecting sound forward in a 2pi hemispherical pattern, and begins to radiate in a manner approaching 4pi spherical radiation, which causes an apparant drop in SPLs below that frequency because less energy is being directed at the listening position, but is spread around the room). All it does is reduce the sensitivity of the speaker above that frequency so it's all ballanced out. Try a 3.5ohm resistor paralleled with a 1.5mH inductor in the + lead. That's fudged, because I'm not sure just how much of an effect the podular baffle will have. Looks like it needs about a 3db drop according to Nelson Pass's measurements though. I don't want to go too far as you haven't got much grunt to spare with that amp for headroom. Should help a bit though. Martin, any thoughts?
I better now beg the forgiveness of TC's ghost, which will now probably haunt me for the next decade. Terry didn't like circuits, and that's putting it mildly. Still, it's a case of what works best for you. I'd rather have mild electronic compensation and a more even balance than none and one which isn't working for whatever reason (room, system -in this case probably the amp, which without compensation is not ideal for FE166E drivers as it's likely going to over-damp them).
The purpose of BSC is not to take 'bumps' out of the response, but to compensate for baffle-step diffraction (a frequency determined by baffle-width, where the speaker stops projecting sound forward in a 2pi hemispherical pattern, and begins to radiate in a manner approaching 4pi spherical radiation, which causes an apparant drop in SPLs below that frequency because less energy is being directed at the listening position, but is spread around the room). All it does is reduce the sensitivity of the speaker above that frequency so it's all ballanced out. Try a 3.5ohm resistor paralleled with a 1.5mH inductor in the + lead. That's fudged, because I'm not sure just how much of an effect the podular baffle will have. Looks like it needs about a 3db drop according to Nelson Pass's measurements though. I don't want to go too far as you haven't got much grunt to spare with that amp for headroom. Should help a bit though. Martin, any thoughts?
I better now beg the forgiveness of TC's ghost, which will now probably haunt me for the next decade. Terry didn't like circuits, and that's putting it mildly. Still, it's a case of what works best for you. I'd rather have mild electronic compensation and a more even balance than none and one which isn't working for whatever reason (room, system -in this case probably the amp, which without compensation is not ideal for FE166E drivers as it's likely going to over-damp them).
Hi,
Fellow member Svante has designed this excellent free software for simulating avtive and passive baffle step compensation methods. http://www.tolvan.com/edge/
Check out the 'Compensation designer' at the bottom right of the page. I have recently used this to build my own line level BSC with excellent results. One (dual) opamp and some resistors and caps is all it takes to get a basic version working. I even powered it with two 9 Volt batteries in the beginning.
It's crazy not to try it when it's this easy.
Unless you mean a notch filter?
Regards,
Martin.
Fellow member Svante has designed this excellent free software for simulating avtive and passive baffle step compensation methods. http://www.tolvan.com/edge/
Check out the 'Compensation designer' at the bottom right of the page. I have recently used this to build my own line level BSC with excellent results. One (dual) opamp and some resistors and caps is all it takes to get a basic version working. I even powered it with two 9 Volt batteries in the beginning.
It's crazy not to try it when it's this easy.
Unless you mean a notch filter?
Regards,
Martin.
Scottmoose said:I think you're talking about baffle-step compensation. God help us, Terry Cain, may he rest in peace, would have a fit if he knew.
All it does is reduce the sensitivity of the speaker above that frequency so it's all ballanced out. Try a 3.5ohm resistor paralleled with a 1.5mH inductor in the + lead. That's fudged, because I'm not sure just how much of an effect the podular baffle will have. Looks like it needs about a 3db drop according to Nelson Pass's measurements though. I don't want to go too far as you haven't got much grunt to spare with that amp for headroom. Should help a bit though. Martin, any thoughts?
I better now beg the forgiveness of TC's ghost, which will now probably haunt me for the next decade. Terry didn't like circuits, and that's putting it mildly. Still, it's a case of what works best for you. I'd rather have mild electronic compensation and a more even balance than none and one which isn't working for whatever reason (room, system -in this case probably the amp, which without compensation is not ideal for FE166E drivers as it's likely going to over-damp them).
New mantra "I must make sure that I have seen all the replies....I must make sure I have seen all the replies".
Ok, the first half of your post was pretty close to greek to me. What I read here is "mumble, mumble, mumble, try with a 3R5 and a 1.5mH" Bingo
Thanks Scott, this was pretty much what I was looking for...I hope.
Cheers
Magura
Definitely not, in fact a SS amp with a high damping factor and some power gives you a lot of flexibility. If you want to reduce the damping factor add some series resistance, this will bring the mid range and high frequency response of the drivers down closer to the bass SPL removing some of the brightness that leads to listener fatigue. Or add a BSC circuit to completely rebalance the entire SPL and compensate for any baffle step response. I do this all the time with my SS amps. It works great, you have the maximum amount of flexibilty with this type of set-up.
but before getting too excited about factoring any system compensation around damping factor, the following might be interesting reading (i.e. third on the list):
http://www.vaughnaudio.com/tech-papers.html
http://www.vaughnaudio.com/tech-papers.html
Well if you filter out all the tube hype and just take it for what it is, it co-relates well with my experience as well. It just took 4 pages to explain what was explained in three lines in an earlier post
It's really quite simple AFAIK, full range stuff like the fostex and so on requires low DF.
So you say you got a high DF amp, well no problem....just add series resistance till it fitts the bill.
Magura
It's really quite simple AFAIK, full range stuff like the fostex and so on requires low DF.
So you say you got a high DF amp, well no problem....just add series resistance till it fitts the bill.
Magura
Sorry to say, I got into a long and heated ******* contest with TC over this very subject with ultimately required me to ban him from my message board. TC believed in SET's and no filters and would not hear anything else.
The Abbey is a TQWT -- a Voigt pipe. It suffers from the same compromises as any other TQWT. ANY tall thin speaker requires about 3dB of BSC. So does the Abbey. The FE166E has a rising frequency response. A TQWT does nothing to address this issue. If you are using a low Z amp, you must do something about it.
Take these numbers with a grain of salt, since they are untested: Use a BSC of 1.5mH||4ohm. Use a zobel of 6.8uF=8ohm. If you are using a low Z amp, and most p-p tubes qualify, use 1-2ohm series resistance BEFORE any other filters.
Let the tweaking begin.
Bob
The Abbey is a TQWT -- a Voigt pipe. It suffers from the same compromises as any other TQWT. ANY tall thin speaker requires about 3dB of BSC. So does the Abbey. The FE166E has a rising frequency response. A TQWT does nothing to address this issue. If you are using a low Z amp, you must do something about it.
Take these numbers with a grain of salt, since they are untested: Use a BSC of 1.5mH||4ohm. Use a zobel of 6.8uF=8ohm. If you are using a low Z amp, and most p-p tubes qualify, use 1-2ohm series resistance BEFORE any other filters.
Let the tweaking begin.
Bob
Would the BSC comments apply to my BIB too? becase i read this, and tried adding some boost to teh lwo end on my bib via eq (+3db to 125hz, then+2 at 250 and +1 at 500) and they sound alot better with rock music! before they sounded too weak for rock music, now i can really get the impact on the kickdrums in death metal.
Depends on what you're running, and where they're positioned. What are you running, and where are they in the room? The BIB shouldn't need any correction if correctly placed in the corners & preferably with a suprabaffle to lower the baffle-step point below the point where it's compensated for by horn gain.
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