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Passive line level crossover?
Does anybody know how to build one of these?
To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. Thank You, Andy |
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#2
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Passive line level crossover?
Andrew,
The easiest and most cost effective solution is to use a pair of Harrison FMod high-pass filters. They make a 12db 50hz set that is just an in-line pair of RCA connectors that install at the input of the amplifier or at the output of the preamp. The frequency is fixed and may vary slightly with your amplifier, but will suit your needs as the sub woofer can be adjusted fully to suit. - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message news  THJb.119004$VB2.322662@attbi_s51...Does anybody know how to build one of these? To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. Thank You, Andy |
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#3
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Passive line level crossover?
Andrew Korsh wrote:
Does anybody know how to build one of these? To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. Thank You, Andy Andy, if you want a 1st order passive high-pass here is how to go: first choose a suitable capacitor, for example a 0.47uF polypropylene (Audyn-Cap MKP). Then calculate the resistor R. (R||100k)+185 = 1/(2*pi*fg*C) with fg=50Hz we get R= 7052 Ohm, you can get this value by putting a 6.8k and 240R in series. Never the less you can also just take a 6.8k alone. You should experiment with different values of R to find the one that will give best results. I would not recommend a second order filter, as the phase change can lead to cancellation of certain frequencies. Maybe you should also modify the filter for the subwoofer to get better results, but this is probably a bit hard for a lay-man. O/P impedance ___ ||C I/P impedance ~-|___|-o--||----+----o---+ 185R || | | .-. .-. | | | | | |R | |100k '-' '-' | | === === GND GND created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de -- ciao Ban Bordighera, Italy electronic hardware designer |
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#4
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Passive line level crossover?
Hej take a look at
http://www.t-linespeakers.org/tech/f...ssiveHLxo.html i don´t have great experience with this subject , i tried this for the low 1st order passive on a Nikko beta . SS -22kohm i think the result was stunning . it was made for my cousin he had tried a lot off souloutions - finnaly this was te tight hi-endbas he wanted. I have never tried 1st order passive high-pass on tube amps, and i would be so pleased to hear about your results. This is a very cheap and overseen way to do crossovers notice it makes AMP 50% less sensitive my keyboard and english is bad -i come from Denmark --not Barcelona wish you luck Andy Andy, if you want a 1st order passive high-pass here is how to go: first choose a suitable capacitor, for example a 0.47uF polypropylene (Audyn-Cap MKP). Then calculate the resistor R. (R||100k)+185 = 1/(2*pi*fg*C) with fg=50Hz we get R= 7052 Ohm, you can get this value by putting a 6.8k and 240R in series. Never the less you can also just take a 6.8k alone. You should experiment with different values of R to find the one that will give best results. I would not recommend a second order filter, as the phase change can lead to cancellation of certain frequencies. Maybe you should also modify the filter for the subwoofer to get better results, but this is probably a bit hard for a lay-man. O/P impedance ___ ||C I/P impedance ~-|___|-o--||----+----o---+ 185R || | | .-. .-. | | | | | |R | |100k '-' '-' | | === === GND GND created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de -- ciao Ban Bordighera, Italy electronic hardware designer |
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#6
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Passive line level crossover?
Hi Bill,
I had a pair of the inline filters that came with my speakers.Didn't like the sound so I stopped using them.Plus they just didn't look good sitting between my Cardas silver RCA plugs and the WBT input jacks.I'm hoping that if I build something with better quality parts i.e. some nice film and foil caps it'll sound better. Cheers, Andy -------------------------------------------------------------- Bill wrote: Andrew, The easiest and most cost effective solution is to use a pair of Harrison FMod high-pass filters. They make a 12db 50hz set that is just an in-line pair of RCA connectors that install at the input of the amplifier or at the output of the preamp. The frequency is fixed and may vary slightly with your amplifier, but will suit your needs as the sub woofer can be adjusted fully to suit. - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message news THJb.119004$VB2.322662@attbi_s51...Does anybody know how to build one of these? =A0=A0To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). =A0=A0I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. =A0=A0=A0=A0Thank You, =A0=A0Andy |
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#7
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Passive line level crossover?
Hi Mark,
My subwoofers have a built in 24db low pass electronic crossover,so this is just for a filter to keep low bass out of the mains.Since the Sapphires are first order phase correct type speakers I want to keep the high pass at 6db.The subz also have a volume control so level matching is not an issue.I also know the mains begin to roll off around 60hz,rated by ACI anechoic (sp?),and I've measured good response down around 40hz with my RatShack SPL meter.So I feel I don't really need the adjustability of an active crossover. I really do believe that an active xover would color the sound more then just one high quality capacitor.After all an active has many caps,resistors,diodes,op-amps,transformer,etc.All of which will color the sound to some extent.And the passive is a LOT cheaper ;-). I think in this situation less is more. Cheers, Andy -------------------------------------------------------------- Mark wrote: (Andrew Korsh) wrote in message news:oTHJb.119004$VB2.322662@attbi_s51... Does anybody know how to build one of these? =A0=A0To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). =A0=A0I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. =A0=A0=A0=A0Thank You, =A0=A0Andy Why passive? Odds are you can dial in much better with an active. Plus you can also low pass the subs with a high order filter (24-48db/oct)that will keep the sub's response down where it belongs. (You don't see too many high order passives.) I believe a good active xover would probably be THE best marginal improvement to any decent system that uses a sub. FWIW. =A0 Mark |
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#8
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Passive line level crossover?
It might, but it will also most likely include more packaging and wire
length so the difference in transparency may be subtle. They do a nice job with the design to make it as minimalist as possible. One thing that you can do with an adjustable or custom filter is to get the spec dead-on, where the FMod is just an aproximation. I can't imagine a better-looking home brew box! - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message ... Hi Bill, I had a pair of the inline filters that came with my speakers.Didn't like the sound so I stopped using them.Plus they just didn't look good sitting between my Cardas silver RCA plugs and the WBT input jacks.I'm hoping that if I build something with better quality parts i.e. some nice film and foil caps it'll sound better. Cheers, Andy -------------------------------------------------------------- Bill wrote: Andrew, The easiest and most cost effective solution is to use a pair of Harrison FMod high-pass filters. They make a 12db 50hz set that is just an in-line pair of RCA connectors that install at the input of the amplifier or at the output of the preamp. The frequency is fixed and may vary slightly with your amplifier, but will suit your needs as the sub woofer can be adjusted fully to suit. - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message news THJb.119004$VB2.322662@attbi_s51...Does anybody know how to build one of these? To go between VTL 5.5 preamp (185 ohm output impedance) and Mccormack DNA-1 amp (100 kohm input impedance). I want to keep low bass out of ACI Sapphire-3 speakers (I have subwoofers).I think a first order roll off starting around 40 or 50 hz would be best. Thank You, Andy |
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#9
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Passive line level crossover?
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#10
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Passive line level crossover?
Stewart wrote"Why do you think that an active xover will colour the
sound?" An active crossover is an entire box chock full of capacitors.Not to mention circuit boards,power supply,wires,solder joints,volume pots,resistors,diodes,etc.Add in an extra interconnect and two input/output jacks.Versus one single capacitor.Which one would have less coloration? Stewart wrote" Are you not using an amplifier to drive your speakers?" Why Yes! I am using an amplifier to drive my speakers! Stewart wrote" Do think that *it* colours the sound?" Of course my amplifier colors the sound.All components color the sound.I wish I didn't have to use an amplifier in my system.But when I tried to run my system without an amplifier the speakers just sat there cold,lifeless,and silent.Not very musically satisfying at all.When I ran my stereo with an amplifier,but without any high-pass filter on the mains it was quite musically satisfying.Could it be more musically satisfying? Perhaps so,that's what I hope to find out. Stewart wrote"BTW, the most phase-accurate combination you can have is to use 24dB/octave for both high-pass and low-pass filters, plus you won't have any problems with a hole or hump in the combined response." Actually I believe the most phase accurate combo would be to run the mains full range,with no crossover.The only phase correct crossover I'm aware of is first order 6db/octave.However I could be wrong about this,I'm no engineer.With continuously variable volume,phase,and X-over on the subz,I'm hoping to avoid any major frequency response anomalies. Cheers, Andy |
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#11
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Passive line level crossover?
Hi Bill,
The caps will go inside the amplifier.Since I'm using WBT jacks with the torx screw type connectors I just have to put one capacitor lead into the rear of the jack and solder the other lead to the end of the input wire.So there is just one extra solder joint,with nothing visible from the outside.The best part is,if I don't like the sound I can just snip the caps off,and slip the wires back into the jacks.No harm-No foul. Regards, Andy ------------------------------------------------------------ Bill wrote: It might, but it will also most likely include more packaging and wire length so the difference in transparency may be subtle. They do a nice job with the design to make it as minimalist as possible. One thing that you can do with an adjustable or custom filter is to get the spec dead-on, where the FMod is just an aproximation. I can't imagine a better-looking home brew box! - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message ... Hi Bill, =A0=A0I had a pair of the inline filters that came with my speakers.Didn't like the sound so I stopped using them.Plus they just didn't look good sitting between my Cardas silver RCA plugs and the WBT input jacks.I'm hoping that if I build something with better quality parts i.e. some nice film and foil caps it'll sound better. =A0=A0Cheers, =A0Andy |
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#12
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Passive line level crossover?
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#13
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Passive line level crossover?
Brilliant. If you are not afraid to modify the amp, that is the best
way to go if you insist on passive. That being said, I would strongly recommend that you use an active device. Even though your sub unit features a variable phase/tilt control, the addition of a 6db filter will cause some phase shift. The formula is not terribly complicated, but you need to be aware that there may already be a capacitor in series to prevent DC from entering the amp. That cap should be substituted for the value that you arrive at using the formula. There should also be a resistor to ground that determines the input impedance. The basic formula is: C = 1/(2pi Rf) where C is the capacitance value that you are looking for and pi is 3.14 (2pi is thus 6.28). R is the input impedance of your amplifier and f is the frequency that will begin the roll-off at 6db/octave. The cap should be rated at least 50v but you will find that most good film and foil types available to audiophiles are anyway. With a capacitor you have a +/- 5% tolorance and you are dealing with two channels. If you go active, you will be able to get a better slope, less phase shift and much tighter tolerances. It is expensive and is what keeps me from doing that actually. I would remove the passive components from my speakers and go active if I had the cash. Digital room correction would be done prior to that. What I do in situations like yours is to run the speakers full range and allow the sub to fill-in below the speakers natural roll-off. That way you are only dealing with the room phasing and not electrical as well. I'm no engineer either and even a good one would want to experiment with what you are suggesting. I would have to side with Stewart and Mark on this one, even though I admire your purist intent. Their advise is very practical, just a bit more costly. - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message news:B0nLb.1550$8H.7712@attbi_s03... Hi Bill, The caps will go inside the amplifier.Since I'm using WBT jacks with the torx screw type connectors I just have to put one capacitor lead into the rear of the jack and solder the other lead to the end of the input wire.So there is just one extra solder joint,with nothing visible from the outside.The best part is,if I don't like the sound I can just snip the caps off,and slip the wires back into the jacks.No harm-No foul. Regards, Andy ------------------------------------------------------------ Bill wrote: It might, but it will also most likely include more packaging and wire length so the difference in transparency may be subtle. They do a nice job with the design to make it as minimalist as possible. One thing that you can do with an adjustable or custom filter is to get the spec dead-on, where the FMod is just an aproximation. I can't imagine a better-looking home brew box! - Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Andrew Korsh" wrote in message ... Hi Bill, I had a pair of the inline filters that came with my speakers.Didn't like the sound so I stopped using them.Plus they just didn't look good sitting between my Cardas silver RCA plugs and the WBT input jacks.I'm hoping that if I build something with better quality parts i.e. some nice film and foil caps it'll sound better. Cheers, Andy |
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#14
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Passive line level crossover?
Andrew Korsh wrote:
Actually I believe the most phase accurate combo would be to run the mains full range,with no crossover.The only phase correct crossover I'm aware of is first order 6db/octave.However I could be wrong about this,I'm no engineer.With continuously variable volume,phase,and X-over on the subz,I'm hoping to avoid any major frequency response anomalies. Cheers, Andy Yes, there are technics to create a 12 or 18 dB sloped x-over without any phase or amplitude changes. I have developed a simple 3-way active crossover doing exaxctly this. There are drawbacks, a large overlapping range and additional power requirements, but the result is absolutly satisfying. If we look at the normal low- and highpass of second order in the Laplace notion: 1 LP: ___________ 1+1/Q*s+s^2 s^2 HP: ___________ 1+1/Q*s+s^2 we can see, however we modify Q or s there is no way to add them so the sum equals 1. The middle part with s is missing. but if we multiply each with a correction bilinear term 1 1+(1/Q +1)s LP: ___________ ___________ 1+1/Q*s+s^2 1+s s^2 (1/Q +1)+s HP: ___________ ___________ 1+1/Q*s+s^2 1+s our sum is exactly 1. This means the output is identical to the input, there is no phase distortion. At the crossover point both ways have a +3dB value for Butterworth low/highpass. Both slopes are absolutly symmetrical at 12dB/oct. The pulse response is just a pulse. These type of filters are used in sonar applications with multiple receivers for different ranges, I never saw them used in audio. Of course the above is just the pure math and the real life filters look still a bit more sophisticated to include the characteristic of the driver+enclosure. ciao Ban http://www.bansuri.my-page.ms/ |
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#15
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Passive line level crossover?
Bill wrote"Brilliant."
Aw shucks Bill,stop it :-)) Bill wrote "If you are not afraid to modify the amp, that is the best way to go if you insist on passive." Well the amp is long since out of warranty,and the mod is so simple and reversible I figure why not.I spoke to Steve Mccormack (just one of the benefits of owning a Mccormack amp,he's such a Mensch!) and he endorsed my plan.If I had to go rooting around the circuit boards I'd surely think twice. Bill wrote " That being said, I would strongly recommend that you use an active device. Even though your sub unit features a variable phase/tilt control, the addition of a 6db filter will cause some phase shift. The formula is not terribly complicated, but you need to be aware that there may already be a capacitor in series to prevent DC from entering the amp. That cap should be substituted for the value that you arrive at using the formula. There should also be a resistor to ground that determines the input impedance. The basic formula is: C = 1/(2pi Rf) where C is the capacitance value that you are looking for and pi is 3.14 (2pi is thus 6.28). R is the input impedance of your amplifier and f is the frequency that will begin the roll-off at 6db/octave. The cap should be rated at least 50v but you will find that most good film and foil types available to audiophiles are anyway." That's the formula I used.I'm getting two .033uf RelCap TFTs (teflon and tin foil) which should give a 3db down point around 50 hz.There is no DC blocking cap that I could find.There is a 100k ohm resistor. Bill wrote " With a capacitor you have a +/- 5% tolerance and you are dealing with two channels. If you go active, you will be able to get a better slope, less phase shift and much tighter tolerances." I ordered from The Parts Connexion.They do 1% matching for a buck a pair.They don't guaranty any particular value within the tolerance,only that the caps will match. Bill wrote " It is expensive and is what keeps me from doing that actually. I would remove the passive components from my speakers and go active if I had the cash. Digital room correction would be done prior to that. What I do in situations like yours is to run the speakers full range and allow the sub to fill-in below the speakers natural roll-off. That way you are only dealing with the room phasing and not electrical as well." That's how I was running.But I recently blew one of the voice coils on my DVC woofer.Got a little rowdy with STP-Core DVD-A (I just got a Universal Player!) Focal has discontinued this unit.Even though ACI has a good supply on hand,eventually they'll be all gone.So I need to be a wee bit more careful. Bill wrote " I'm no engineer either and even a good one would want to experiment with what you are suggesting. I would have to side with Stewart and Mark on this one, even though I admire your purist intent. Their advise is very practical, just a bit more costly." Eh,I'll run it up the flag-pole etc.Can always go active at some future point. Cheers, Andy |
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#16
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Passive line level crossover?
Hi Stewart,
Thanks for your comments.So a 24db/oct X-over can be phase correct.Well,live'n'learn huh? Still gonna go the passive route first,see if I like it.Others have used this method with some (claimed) success.After all,why jump straight to the more complex/expensive solution,when the simpler/cheaper method -might- work? I'll give it a listen see how it goes. Just in case the passive doesn't work out,care to give me some recommendations for 24db/oct high pass filters? Regards, Andy -------------------------------------------------------------- Stewart wrote: Stewart wrote"Why do you think that an active xover will colour the sound?" =A0=A0An active crossover is an entire box chock full of capacitors.Not to mention circuit boards,power supply,wires,solder joints,volume pots,resistors,diodes,etc.Add in an extra interconnect and two input/output jacks.Versus one single capacitor.Which one would have less coloration? Impossible to say without listening to them, but I've certainly heard active crossovers which were acoustically transparent when compared to a bypass. =A0=A0Stewart wrote" Are you not using an amplifier to drive your speakers?" Why Yes! I am using an amplifier to drive my speakers! Stewart wrote" Do think that *it* colours the sound?" =A0=A0Of course my amplifier colors the sound.All components color the sound. No, they don't, although this is a persistant urban myth! I wish I didn't have to use an amplifier in my system.But when I tried to run my system without an amplifier the speakers just sat there cold,lifeless,and silent.Not very musically satisfying at all.When I ran my stereo with an amplifier,but without any high-pass filter on the mains it was quite musically satisfying.Could it be more musically satisfying? Perhaps so,that's what I hope to find out. =A0=A0Stewart wrote"BTW, the most phase-accurate combination you can have is to use 24dB/octave for both high-pass and low-pass filters, plus you won't have any problems with a hole or hump in the combined response." =A0=A0Actually I believe the most phase accurate combo would be to run the mains full range,with no crossover.The only phase correct crossover I'm aware of is first order 6db/octave.However I could be wrong about this,I'm no engineer.With continuously variable volume,phase,and X-over on the subz,I'm hoping to avoid any major frequency response anomalies. As with 6dB/octave, a properly configured 24dB/octave crossover is also phase-linear and constant-power, although 12 and 18dB/octave designs are not. If you combine slopes, you *will* suffer a hump or hole in the combined response. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#17
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Passive line level crossover?
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