Dear Stanwal: IMHO in almost all audio subjects alternatives exist trade-offs, which one we choose is up to each one of us: nothing is perfect till today.
As with passive electronics parts as: inductors, caps, resistors, transformers and the like the best is NO inductor/caps/resist/transfi in the audio signal but sometimes that is imposible to achieve so we have to analize alternatives to choose the one we are satisfied with the one makes less or the lower harm/degradation to the audio signal.
Same happen with active crossovers but exist a degradation " gradation " of the audio signal depending how and where we are using that active electronic crossover and of course the crossover design.
It is not the same to use the active internal subwoofer crossover that to use a FM Acoustic external one: way/wider difference!.
Now, through the years I learned about the use of subwoofers in an audio system, I understand the objectives/targets to use subwoofers: the whys we use subwoofers.
Obviously that the main and " natural " reason is to go deeper in the bass audio system management range. This characteristic always is important but exist other reasons that even the importance of it:
- not only lower bass frequency range but better quality of that bass range.
- achieve lower IMD speaker distortions. The mid bass is clean, the midrange is clean, the highs are clean: high resolution every where ( the distortions are almost gone ), and now you can really hear for the first time the MUSIC. Clean does not means analitical but means: accurate with more musical information that gives the real music " feeling ".
Intermodulation Distortions: Almost any three ways speaker ( all two ways/one way ) has it's crossover frecuency ( low driver ) between 120Hz and 450Hz. I can assume that any of ours speakers system goes down flat ( at least ) between 60Hz to 20Hz.
What does that means ?, well that a single driver has to reproduce frecuencies/harmonics from 20Hz/60Hz to 120Hz/450Hz. With that kind of frecuency range here exist a great intermodulation distortions that put it's " color " on the sound reproduction.
You have to imagine that that single woofer/driver has to reproduce, at the same " time ", a 30Hz frecuency along a 350Hz frecuency: here is where exist that IM that gives heavy distortions in what we hear ( there is no perfect driver: moving coil, electrostatic, ribbon, etc.. The speaker designers has to choose the best " trade offs ", but the distortions are there. ): less clarity, less resolution, less precision, less natural balance, less pitch, les, less, less......., and this is what we are really hearing: LESS MUSIC.
If you read any manufacturer specifications on their speakers they never " write " the value of the IM or harmonic distortions, they tell us the frecuency range and how is flat on that range but never " talk " about distortions. I think that you know that when we have a speaker frecuency specifications, say: 28Hz to 22kHz +,- 3db, that is a very nice spec, that speaker low driver don't stop at 28hZ it's goes a few hertz below that frecuency with heavy harmonic distortion that increase the IM distortion of the sound reproduction of that driver and these additional distortions have a severe degradation in the reproduction of the MUSIC.
-liberate the main amplifiers to handle that lower bass permiting a better amplifier quality performance.
- An improvement in the soundstage reproduction in all parameters: deep, front/side location, wide of the stage, etc...
- the main speakers amplifiers works best ( less distortion, more headroom, less chance of clipping, less amplifier stress, etc...) with out to handle the frecuencies range that now are handle by the dedicated subwoofers amplifiers. This is important for an SS amplifier but for the tubes ones is a must.
- Now the low bass frecuencies are handle for a dedicated driver that was build with specifics characteristics for to work in that frecuency range and this low bass driver is matched with an amplifier ( self powered subwoofers ) that was build with specifications that mates excatly what the low bass drivers needs about: frecuency response, output impedance, damping, power, etc..... You can't ask for more!!!
- Not only the IM distortion goes down but the harmonic distortion of the low driver of your main speakers goes down too, Btw, the whole harmonic distortion goes down, because ( in the case of my Velodyne's less than 0.5%: with's yours? ) ) the harmonic distortion of a well self powered designed subwoofer is usually " very low ". This means ( again ) less coloration: MORE MUSIC.
Now, IMHO any passive loadspeakers where its woofer/lows-driver crossover 120hz can achieve all those benefits with the use/system-integration of two self powered subwoofers running in true stereo fashion, this means that the main speakers not hnadle any more the low bass frequency range: this is handle where it belongs to: with the subwoofers.
In my system I don't use an external electronic crossover to split the main speakers frequency range and the subwoofer frequency range both handle it.
I use at the amplifiers input a first order slope through a very low value teflon cap along a 275 resistor. In this way I let " untouched " the audio signal handled by the main amplifiers/speakers.
The second output in my phonolinepreamp goes connected to the self electronic active crossover in the subwoofers. I made several changes/modifications in the subwoofers to achieve the lower audio signal degradation/distortions.
Stanwal, you have to try it. IMHO there is no argument against what I post other that to " live " the experience in your own system.
Btw, my choose for crossover frequency was: 76.8hz. ( I think?? ).
Regards and enjoy the music,
R.
As with passive electronics parts as: inductors, caps, resistors, transformers and the like the best is NO inductor/caps/resist/transfi in the audio signal but sometimes that is imposible to achieve so we have to analize alternatives to choose the one we are satisfied with the one makes less or the lower harm/degradation to the audio signal.
Same happen with active crossovers but exist a degradation " gradation " of the audio signal depending how and where we are using that active electronic crossover and of course the crossover design.
It is not the same to use the active internal subwoofer crossover that to use a FM Acoustic external one: way/wider difference!.
Now, through the years I learned about the use of subwoofers in an audio system, I understand the objectives/targets to use subwoofers: the whys we use subwoofers.
Obviously that the main and " natural " reason is to go deeper in the bass audio system management range. This characteristic always is important but exist other reasons that even the importance of it:
- not only lower bass frequency range but better quality of that bass range.
- achieve lower IMD speaker distortions. The mid bass is clean, the midrange is clean, the highs are clean: high resolution every where ( the distortions are almost gone ), and now you can really hear for the first time the MUSIC. Clean does not means analitical but means: accurate with more musical information that gives the real music " feeling ".
Intermodulation Distortions: Almost any three ways speaker ( all two ways/one way ) has it's crossover frecuency ( low driver ) between 120Hz and 450Hz. I can assume that any of ours speakers system goes down flat ( at least ) between 60Hz to 20Hz.
What does that means ?, well that a single driver has to reproduce frecuencies/harmonics from 20Hz/60Hz to 120Hz/450Hz. With that kind of frecuency range here exist a great intermodulation distortions that put it's " color " on the sound reproduction.
You have to imagine that that single woofer/driver has to reproduce, at the same " time ", a 30Hz frecuency along a 350Hz frecuency: here is where exist that IM that gives heavy distortions in what we hear ( there is no perfect driver: moving coil, electrostatic, ribbon, etc.. The speaker designers has to choose the best " trade offs ", but the distortions are there. ): less clarity, less resolution, less precision, less natural balance, less pitch, les, less, less......., and this is what we are really hearing: LESS MUSIC.
If you read any manufacturer specifications on their speakers they never " write " the value of the IM or harmonic distortions, they tell us the frecuency range and how is flat on that range but never " talk " about distortions. I think that you know that when we have a speaker frecuency specifications, say: 28Hz to 22kHz +,- 3db, that is a very nice spec, that speaker low driver don't stop at 28hZ it's goes a few hertz below that frecuency with heavy harmonic distortion that increase the IM distortion of the sound reproduction of that driver and these additional distortions have a severe degradation in the reproduction of the MUSIC.
-liberate the main amplifiers to handle that lower bass permiting a better amplifier quality performance.
- An improvement in the soundstage reproduction in all parameters: deep, front/side location, wide of the stage, etc...
- the main speakers amplifiers works best ( less distortion, more headroom, less chance of clipping, less amplifier stress, etc...) with out to handle the frecuencies range that now are handle by the dedicated subwoofers amplifiers. This is important for an SS amplifier but for the tubes ones is a must.
- Now the low bass frecuencies are handle for a dedicated driver that was build with specifics characteristics for to work in that frecuency range and this low bass driver is matched with an amplifier ( self powered subwoofers ) that was build with specifications that mates excatly what the low bass drivers needs about: frecuency response, output impedance, damping, power, etc..... You can't ask for more!!!
- Not only the IM distortion goes down but the harmonic distortion of the low driver of your main speakers goes down too, Btw, the whole harmonic distortion goes down, because ( in the case of my Velodyne's less than 0.5%: with's yours? ) ) the harmonic distortion of a well self powered designed subwoofer is usually " very low ". This means ( again ) less coloration: MORE MUSIC.
Now, IMHO any passive loadspeakers where its woofer/lows-driver crossover 120hz can achieve all those benefits with the use/system-integration of two self powered subwoofers running in true stereo fashion, this means that the main speakers not hnadle any more the low bass frequency range: this is handle where it belongs to: with the subwoofers.
In my system I don't use an external electronic crossover to split the main speakers frequency range and the subwoofer frequency range both handle it.
I use at the amplifiers input a first order slope through a very low value teflon cap along a 275 resistor. In this way I let " untouched " the audio signal handled by the main amplifiers/speakers.
The second output in my phonolinepreamp goes connected to the self electronic active crossover in the subwoofers. I made several changes/modifications in the subwoofers to achieve the lower audio signal degradation/distortions.
Stanwal, you have to try it. IMHO there is no argument against what I post other that to " live " the experience in your own system.
Btw, my choose for crossover frequency was: 76.8hz. ( I think?? ).
Regards and enjoy the music,
R.