Active filters? (Off Topic)

by carlesdg, Monday, February 02, 2009, 14:35 (3270 days ago)

Hello,

I wan to know the opinion of the forum members about the use of external active filters (analogic BSS-318)instead of the passive filter normally used.

Do you recommend it?

Best regards

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Active filters?

by Bert @, Monday, February 02, 2009, 20:27 (3270 days ago) @ carlesdg

Hello Carles,

I wan to know the opinion of the forum members about the use of external active filters (analogic BSS-318)instead of the passive filter normally used.

Do you recommend it?

In general an active system can perform better than a passive filtered system assuming that people know what they are doing of course...

Passive parts do have their negative influence to the sound though (any part or extra connection is taking away something nice), if it should be recommended depends on the compromise as nothing is perfect.

Not much help eh? :grin:

How are you going to use your active filter? What are you trying to gain while using it?

Bert

--
BD-Design - Only the Best!

Active filters?

by carlesdg, Tuesday, February 03, 2009, 17:55 (3269 days ago) @ Bert

Hello Bert,

yes, I agree, not to much help :grin:

Using an active filter I wish to remove the passive filters and try to obtain a more dynamic sound (and detailed?).

Do you have an opinion about the performance of the analogic filter BSS 318? I have a digital BSS 336 and it gives to the sound a digital sense that I don´t like.

Best regards
Carles

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Active filters?

by Bert @, Wednesday, February 04, 2009, 06:36 (3269 days ago) @ carlesdg

Hello Carles,

Using an active filter I wish to remove the passive filters and try to obtain a more dynamic sound (and detailed?).

That is not much helping either... :no:

I was more looking for the complexity you want to replace for an active solution. Basically I can state that I do not think that you will be able to improve the sound by just replacing a passive crossover for an active version, it just does not work if you are not able to measure the speakers after.

It is not just about crossing at a certain frequency with a certain electrical character (Linkwitz, Bessel, etc.) but it has everything to do with the speaker character used where a passive crossover usually is doing more than just crossing somewhere (not talking about Monacor or Visaton ready made passive crossovers...)

Do you have an opinion about the performance of the analogic filter BSS 318? I have a digital BSS 336 and it gives to the sound a digital sense that I don´t like.

I have no idea but I do not think that it will make much of a difference as the net result (with all respect and what you are probably hearing) is not the digital part at first but the wrongly applied principle (the speaker is changed into something incomparable).

Bottom line.... if the designer of the loudspeaker knows what he is doing and applied a proper working passive crossover to his design then an active crossover will always make the sound worse (at least something different) if not applied by the same designer to maintain the original speaker characteristics...

The art to make a speaker sound good has nothing to do with the use of active or passive crossovers.

Bert

--
BD-Design - Only the Best!

Active filters?

by carlesdg, Wednesday, February 04, 2009, 12:03 (3269 days ago) @ Bert

Hello Bert,

I have no idea but I do not think that it will make much of a difference as the net result (with all respect and what you are probably hearing) is not the digital part at first but the wrongly applied principle (the speaker is changed into something incomparable).

When I told that I don't like the sound of my digital active filter, it was without remove the passive filter of my loudspeakers. That mean that I only put the digital filter in the sound path, without any kind of adjustment. The sound signal was only passing through the digital active filter.

I know that it is difficult to obtain best results with an active filter tuned by not professional people like me. Anyway I have a basic sound measure equipment.

Best regards
Carles

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Active filters?

by Bert @, Thursday, February 05, 2009, 16:07 (3267 days ago) @ carlesdg

Hello Carles,

When I told that I don't like the sound of my digital active filter, it was without remove the passive filter of my loudspeakers. That mean that I only put the digital filter in the sound path, without any kind of adjustment. The sound signal was only passing through the digital active filter.

Ah, okay and logical... anything that is connected in the signal path is doing something with the sound and that is usually by making it worse. Sometimes adding things can bring improvements but then it is basically curing basic problems and gives a better compromise... :grin:

Bert

--
BD-Design - Only the Best!

Active filters?

by DCA @, Wednesday, February 04, 2009, 16:43 (3268 days ago) @ Bert

Hello Carles,

I wan to know the opinion of the forum members about the use of external active filters (analogic BSS-318)instead of the passive filter normally used.

Do you recommend it?


In general an active system can perform better than a passive filtered system assuming that people know what they are doing of course...

Passive parts do have their negative influence to the sound though (any part or extra connection is taking away something nice), if it should be recommended depends on the compromise as nothing is perfect.

Not much help eh? :grin:

How are you going to use your active filter? What are you trying to gain while using it?

Bert

If you forgive me Bert, doing caps, inductors and resistors that are being used in passive, active and digital filters by clients, I've created the following rule of thump: The part will have an influence on the sound regardless of the filter being passive, active or digital, what matters most is that the filter type is done correctly. A properly designed passive filter sounds better than a bad active and vice versa. On the matter of less is more, I don't per se view the active solution as less but rather a different approach. I agree wholeheartedly with your comment regarding the relevant compromise being the determinator, nothing is indeed perfect.

Active filters?

by madprofessor ⌂, 27777 Ganderkesee, Germany, Tuesday, February 03, 2009, 19:42 (3269 days ago) @ carlesdg

Hallo!
To my experience, electronic x-overs with too much of possible adjustments tend to degrade the sound. For example: All the filters are constructed to operate in a wide area, which causes automatically some internal impedance problems.
I used the passive filtering, as suggested by Bert for the Bd-15. That worked quite well, but due to the low input impedance of my bass-amp, I had to make some compromises.
Now I use an active x-over from Thel audio Germany. That one has the advantage of a narrow but very fine adjustable range. The basic range like x-over frequency in the range from 200- 500 Hz ist selected by soldered capacitors, the fine-tuning is done by swithchable Resistors.
I use that x-over only for bass, midrange/trebble is filtered with passive components.
For myself, I´m satisfied with that system.
Best regards
Stephan

Active filters?

by Don Reid, Rural Northwest Georgia, USA, Wednesday, February 04, 2009, 16:33 (3268 days ago) @ carlesdg

Hi Carlesdg,

I have chosen to use active filters for many years. My current choice is the DEQX HDP-3 digital crossover and room, time, and phase correction device. This is a true audiophile component.

I use it to triamplify a speaker system consisting of 18 cubic ft. folded corner horn woofers with an in room response of 19Hz to 160Hz +or- 2 dB, Oris 150 horns driven by AER MD3 drivers and Fostex T900A horn tweeters. The DEQX allows for very high order, linear phase, seamless crossovers and melds the three disparate drivers into a very coherent musically pleasing whole. Even though the acoustic centers of the woofers and drivers in the Oris horns are physically more than 5 meters apart the DEQX time aligns them as though they were separated by no more than 3 mm.

I really pity those who are still attempting to bludgeon the high level signal around with capacitors and colis which very frequently deviate 5% or more, sometimes much more, from their specified values. Passive filters also prevent the quite important benifits of connecting the power amplifier directly to the driver and also create insertion losses and diminished damping factors. However the main problem with passive filters is that they can not even attempt to accomplish many of the things that the latest generation of digital active filters accomplish so elegantly, musically and easily.

All of this is not surprising. When electric phonographs were introduced many claimed that the old wind up acoustic phonograps sounded better. When stereo was introduced many claimed that mono sounded better, and clung to their old mono systems for years. Progress comes hard for some.

Don Reid

Active filters?

by carlesdg, Thursday, February 05, 2009, 18:33 (3267 days ago) @ Don Reid

Hello Don,

I never heard before about this brand. Your digital filter seems very complete and useful, specially if it don´t degrade the sound. The obvious cons is the price...

In my actual system (biamped and passive filtered), I have a BSS 336 for to do a little job in the bass section in order to correct the room response below 200hz, or so.

Best regards
Carles

may i ask a silly question?

by anubisgrau, Wednesday, February 11, 2009, 17:16 (3261 days ago) @ Don Reid

how do active crossover compensate for an efficency difference between the drivers?

a classic question: in case i want to run an active crossover with 115db mid/hi and 100db bass, is there still a need for a passive filter that would lower the efficiency of a mid/hi or there are settings with an active crossover that deal with this.

thanks!

may i ask a silly question?

by carlesdg, Wednesday, February 11, 2009, 17:53 (3261 days ago) @ anubisgrau
edited by carlesdg, Wednesday, February 11, 2009, 18:37

It depends on the active filter. My BSS 336 have a digital gain adjust of -15db to +15db
plus an analogic gain adjust of -6 (or 3?) to + 6db, both for each way or L/R channel.

Regards

Avatar

may i ask a silly question?

by Bert @, Thursday, February 12, 2009, 09:27 (3261 days ago) @ anubisgrau

Hi Gordan,

It depends on the input sensitivity of the used amplifiers and on the sensitivity of the drivers how much gain difference you'll need. To achieve this can be done with some active crossovers (if they have their own volume control) and if not then just it is not hard to attenuate the amplifier on its input if it needs attenuation.

Last thing I would do is to use passive components between the amplifier and loudspeaker to reduce gain.

Bert

--
BD-Design - Only the Best!

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