I am finally done with the HIVI b3s project from zaphs web page, and i am very pleased...these things really do have clean sound...
you may remember all of my crossover issues/questions and such that i dealt with a few weeks ago...i avoided the issue and just built the filter as he showed just to see how it turned out...i thought maybe i could adjust the EQ on the minisystem enough to make this work, but i decided that this wasnt the best idea, so I have decided to start researching the most reasonable options for fixing this issue...
my search led me to the partsexpress Fmods, shown here:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-256
would this be an effective solution? it seems a bit easier than designing one myself since finding the input impedence of the minisystem amp might prove to be more trouble than its worth...i would rather drop 25 bucks on this is i knew it would work...but it is a caraudio Fmod...would it work in this case?
PS thanks to all who helped me get this project rolling
you may remember all of my crossover issues/questions and such that i dealt with a few weeks ago...i avoided the issue and just built the filter as he showed just to see how it turned out...i thought maybe i could adjust the EQ on the minisystem enough to make this work, but i decided that this wasnt the best idea, so I have decided to start researching the most reasonable options for fixing this issue...
my search led me to the partsexpress Fmods, shown here:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-256
would this be an effective solution? it seems a bit easier than designing one myself since finding the input impedence of the minisystem amp might prove to be more trouble than its worth...i would rather drop 25 bucks on this is i knew it would work...but it is a caraudio Fmod...would it work in this case?
PS thanks to all who helped me get this project rolling
Isn't the so called FMOD just a passive line-level crossover? It doesn't require any power and it is inline with the signal before any serious amplfication stages take place.
If this is the case then you'd have similar types of impedance matching problems as building your own, only, it won't be optimal for your system. Impedance matching is really only stabilizing the circuitry to perform at it's optimal potential.
Anyway, please correct me if I'm wrong, which I probably am.
If this is the case then you'd have similar types of impedance matching problems as building your own, only, it won't be optimal for your system. Impedance matching is really only stabilizing the circuitry to perform at it's optimal potential.
Anyway, please correct me if I'm wrong, which I probably am.
Well, one of those would work, but you don't want a 150hz low pass for the B3S! A 150hz high pass would probably be fine.
However, 25$ is a little 'up there' for passive line filters, seeing as how they are a jack, two resistors, and two capacitors each.
They are second order, passive line level cross over filters, which are very simple, and aren't hard to design.
Here is what I'd do... Chop up a simple interconnect (or make your own), and use a little piece of perfboard (or just in the air point to point wiring) to make the filter with the interconnect wired along it. I make little attenuators this way all the time to balance out channels or whatnot.
Passive line filters aren't perfect, but they are way better than a passive speaker level filters for something simple and cheap like this.
Check out this page for how to design the line level filter. Use decent metal film 1% resistors, and decent polypropylene film caps. They won't cost much, because they don't need high voltage ratings.
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
Good luck! I'm building three of the B3S speakers soon, once I get access to my friend's table saw and router.
peace,
sam
However, 25$ is a little 'up there' for passive line filters, seeing as how they are a jack, two resistors, and two capacitors each.
They are second order, passive line level cross over filters, which are very simple, and aren't hard to design.
Here is what I'd do... Chop up a simple interconnect (or make your own), and use a little piece of perfboard (or just in the air point to point wiring) to make the filter with the interconnect wired along it. I make little attenuators this way all the time to balance out channels or whatnot.
Passive line filters aren't perfect, but they are way better than a passive speaker level filters for something simple and cheap like this.
Check out this page for how to design the line level filter. Use decent metal film 1% resistors, and decent polypropylene film caps. They won't cost much, because they don't need high voltage ratings.
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
Good luck! I'm building three of the B3S speakers soon, once I get access to my friend's table saw and router.
peace,
sam
More about passive line level crossovers: http://www.silcom.com/~aludwig/Sysdes/Crossove_Design.htm#Bi_amping
jaygeorge1979 said:
Hi,
It would be useful if you describe the complete system
and how you intend to use the line level filters.
If the mini system has a line level input, and you are using
an active sub, and you are driving both from a line output,
then an inline high pass filter for the mini system will work.
/sreten.my mini system does have line level input, and i am using an active subwoofer, but not with the mini system...this is all for my computer setup, so i am using the front speaker output on my soundcard to run to my minisystem for the mids/highs, and the rear speaker output on my soundcard for the active sub...so im guessing the Fmod would work
and yes i know i need a high pass fmod, i just posted the wrong link....DOH!
i would rather design it myself, but last time i researched this it said i needed to find input impedence of the amplifier, and i didnt have the tools to do it, so i figured why not spend a little extra and get one thats already built....unless this thinking is frowned upon by the DIY community
thanks to all replies thus far
and yes i know i need a high pass fmod, i just posted the wrong link....DOH!
i would rather design it myself, but last time i researched this it said i needed to find input impedence of the amplifier, and i didnt have the tools to do it, so i figured why not spend a little extra and get one thats already built....unless this thinking is frowned upon by the DIY community
thanks to all replies thus far
I was trying to imply that you'd still have the same impedance matching problems with the Fmod as you would with any other PLL XO.
If you designed your own 'Fmod' you'd be at the same place as you would be with purchasing your own 'Fmod' except that you'd have paid more money.
P.S.,
You may consider 'borrowing' some $$ for the tools because if you're just entering DIY you'll eventually learn that you'll use them very, very often.
If you designed your own 'Fmod' you'd be at the same place as you would be with purchasing your own 'Fmod' except that you'd have paid more money.
P.S.,
You may consider 'borrowing' some $$ for the tools because if you're just entering DIY you'll eventually learn that you'll use them very, very often.
for the Fmods tho, they dont specify anything about input impedence, so how would i go about choosing which one that works? there is only one high pass 200 Hz crossover that i see
so im asking how this differs from building your own...cuz to build your own the input impednece must be known, but to buy one, i cant find anything mentioning input impedence
so im asking how this differs from building your own...cuz to build your own the input impednece must be known, but to buy one, i cant find anything mentioning input impedence
If you built your own you'd have the impedance matched exactly to your amplifiers and thus would have less distortion, clipping and more head room. UNLESS, the fmod that you buy happens to be designed for your amp's impedances.
From what I've read about the B3s, it seems that they are useless from 100-300Hz so maybe 200Hz. is not going to work.
Can your woofer produce some mid-bass into the listening area?
From what I've read about the B3s, it seems that they are useless from 100-300Hz so maybe 200Hz. is not going to work.
Can your woofer produce some mid-bass into the listening area?
Hi,
the fmods probably work on this basis :
Input impedance is assumed to be 500 ohms or less.
Loading impedance of the connected amplifier is 20K ohm or more.
(I think 30K to 100K is fairly typical for a car amplifier)
The plug will contain a capacitor, inductor and resistor.
The resistor will be in parallel with the output and be ~ 5k ohm,
so the output impedance of the filter will be near say 4.7k ohm
for nearly all amplifiers it is used with.
/sreten.
the fmods probably work on this basis :
Input impedance is assumed to be 500 ohms or less.
Loading impedance of the connected amplifier is 20K ohm or more.
(I think 30K to 100K is fairly typical for a car amplifier)
The plug will contain a capacitor, inductor and resistor.
The resistor will be in parallel with the output and be ~ 5k ohm,
so the output impedance of the filter will be near say 4.7k ohm
for nearly all amplifiers it is used with.
/sreten.Bose(o) said:
I am toying around with a computer crossover with my b3s speakers...the crossover filters out all sound, so its affecting the subwoofer too....i decided at 200 Hz they performed the best, no distortion or anythjing at 200, despite where the gains are..i will conduct more tests later, this was just a quickie...
Not to hijack, but just to satisfy the desire for pictures, here is one of my B3S speakers, just assembled tonight (the glue is barely dry) for that obligatory first test.
I'm making three, one for a center channel, and two for left and right surrounds. The one on the TV has a 'gentler' baffle step compensation circuit, and the surrounds have no baffle step compensation, since they will be wall mounted in the corner (not perfect, but its what I've got).
Yes, I know the baffle on this picture is 1/8" too long on each side. How many times are you supposed to measure before you cut? Actually, I started with 3/4" mdf for all my dimensions, and then ended up finding 5/8" in the basement. Redid all the dimensions (except that one, apparently). Flush trimmer will take care of that little problem, though.
Also, I'll be roundover-ing all edges, sanding, and prepping for the obligatory gloss black paintjob. The allen bolts are countersunk to be perfectly flush (they will be with the paint, at least), and will be used to mount a magnetic grill of some sort (or maybe not).
Anyway, sorry to hijack, back to your regularly scheduled program.
peace,
sam
I'm making three, one for a center channel, and two for left and right surrounds. The one on the TV has a 'gentler' baffle step compensation circuit, and the surrounds have no baffle step compensation, since they will be wall mounted in the corner (not perfect, but its what I've got).
Yes, I know the baffle on this picture is 1/8" too long on each side. How many times are you supposed to measure before you cut? Actually, I started with 3/4" mdf for all my dimensions, and then ended up finding 5/8" in the basement. Redid all the dimensions (except that one, apparently). Flush trimmer will take care of that little problem, though.
Also, I'll be roundover-ing all edges, sanding, and prepping for the obligatory gloss black paintjob. The allen bolts are countersunk to be perfectly flush (they will be with the paint, at least), and will be used to mount a magnetic grill of some sort (or maybe not).
Anyway, sorry to hijack, back to your regularly scheduled program.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
peace,
sam
jaygeorge1979 said:
Hi,
the input impedance is usually determined by a current limiting
resistor fiited to a preamp out. For Most op-amps this is 250 to 300R.
For most calculations you can ignore it and assume it is zero.
The output or load impedance can be assumed to the input impedance
of the amplifer if you know it, if you don't using a known parallel load
of lower likely impedance takes some of the guesswork out.
But I think for 200Hz (with 4.7K load) you will have diificulties
sourcing the kind of low current signal inductor you will need.
:0/sreten.
I don't think you need a signal inductor.. You can do a second order highpass with just two capacitors, and two resistors. I'm willing to bet that the FMOD doesn't have an inductor in it, since it would get all gibbered with that metal case. Its probably just surface mount capacitors and resistors.
Using the calculations on this page:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
We can run some numbers...
If we set R1 to 5000ohms, and our crossover frequency at 200hz then:
C1 would then be 1/(2*pi*f*R1), or 159.2nF
C2 would be C1/10, or 15.92nF
If the input impedence of the amplifier is very high, over 1 megaohm (which most opamp buffered amps are, which yours probably is (any other opinions on this???)), then we can basically neglect its parallel influence, and set R2 to be 10*R1, or 50kohms.
So... For a second order highpass, 12db per octave, here are the values. Please check my math, I ran these numbers during my lunch break.
f = 200hz
R1 = 5k ohms
R2 = 50k ohms
C1 = 159.2nF
C2 = 15.9nF
peace,
sam
Using the calculations on this page:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
We can run some numbers...
If we set R1 to 5000ohms, and our crossover frequency at 200hz then:
C1 would then be 1/(2*pi*f*R1), or 159.2nF
C2 would be C1/10, or 15.92nF
If the input impedence of the amplifier is very high, over 1 megaohm (which most opamp buffered amps are, which yours probably is (any other opinions on this???)), then we can basically neglect its parallel influence, and set R2 to be 10*R1, or 50kohms.
So... For a second order highpass, 12db per octave, here are the values. Please check my math, I ran these numbers during my lunch break.
f = 200hz
R1 = 5k ohms
R2 = 50k ohms
C1 = 159.2nF
C2 = 15.9nF
An externally hosted image should be here but it was not working when we last tested it.
peace,
sam
thanks alot sam, your post was very helpful
the amplifier i am using is an older aiwa minisystem with regular line lever inputs, and you are saying we assume the input impedence to be very high? i understand why assuming it to be very large allows us to ignore it in the equation, and i would love to do that cuz that makes this thing rediculously simple...
i checked ur numbers, and you are correct...but the formulas do say to make sure and include the input impedence in the calculations...i noticed sreten also said i can ignore input impedence in most calculations, so i may just go ahead and do that
unless anyone thinks its a bad idea...
the amplifier i am using is an older aiwa minisystem with regular line lever inputs, and you are saying we assume the input impedence to be very high? i understand why assuming it to be very large allows us to ignore it in the equation, and i would love to do that cuz that makes this thing rediculously simple...
i checked ur numbers, and you are correct...but the formulas do say to make sure and include the input impedence in the calculations...i noticed sreten also said i can ignore input impedence in most calculations, so i may just go ahead and do that
unless anyone thinks its a bad idea...- Status
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