Bi-Amp question

PolkMaster1
PolkMaster1 Posts: 847
edited March 2011 in DIY, Mods & Tweaks
If one decides to make a pair of bi-amps, can we just use speaker crossover or is an external crossover needed?

Thanks.
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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    To realize the full benifits of bi-amping requires the removal of the internal passive crossover, then using an external line level active crossover in it's stead.However it's not as simple as plug and play,as with passive crossovers the active needs to be configured correctly (ie.roll off rates,frequency,delay)for the the actual drivers it's being used with.Failing to do so will likely result in performance that is actually inferior to the stock passive network.

    Heres a good primer on active vs passive biampng. http://sound.westhost.com/biamp-vs-passive.htm
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  • PolkMaster1
    PolkMaster1 Posts: 847
    edited March 2011
    Thanks for the link to Elliot Sound Products. I have read a few of his articles in the past.

    I am thinking the ideal active croosver is to take out the passive croosver, and use those parts to make an active crossover. Woudl that be all to it, or is it much more work than that? Based on what a couple of articles I read so far, the latter sounds true.

    Thanks.
    Statistics show that 98% of us will die at some point in our lifetime.

    The other 2% will work for WalMart.
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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    PolkMaster1 wrote: »
    I am thinking the ideal active croosver is to take out the passive croosver, and use those parts to make an active crossover.
    No the passive networks parts cannot be used in the active unit. An active crossover is an electronic component much like a preamp that utilizes opamps(thus the term active).With the active the frequency division is done at at line level ahead of the amplifiers, whereas the passive network is after the amplifer.


    Heres an example of an active xover.http://www.marchandelec.com/xm9.html
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  • PolkMaster1
    PolkMaster1 Posts: 847
    edited March 2011
    OK, well I have redone my crossovers with Soniccaps and Mills. I have been very pleased with the results, but now I am getting the hunger for more. A couple of questions:

    1. Will the Marchand Electronics Active Crossover (or even a competing Active XO) be all I need? I assume I will need 2 - one for the lows and one for the highs for a stereo set
    2. Aside from getting more power, will I get better results from an active crossover vs. a passive crossover that uses Mills and Soniccaps?

    Thanks for your input FTGV and anyone else who responds.
    Statistics show that 98% of us will die at some point in our lifetime.

    The other 2% will work for WalMart.
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  • PolkMaster1
    PolkMaster1 Posts: 847
    edited March 2011
    I guess another question that comes up, would it be better to use film caps over electrolytics for an active crossover?

    I am going under the assumption that the electrolytics can be replaced by film caps for the same values.
    Statistics show that 98% of us will die at some point in our lifetime.

    The other 2% will work for WalMart.
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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    PolkMaster1 wrote: »
    OK, well I have redone my crossovers with Soniccaps and Mills. I have been very pleased with the results, but now I am getting the hunger for more. A couple of questions:

    1. Will the Marchand Electronics Active Crossover (or even a competing Active XO) be all I need? I assume I will need 2 - one for the lows and one for the highs for a stereo set
    The Marchand in the link is a complete stereo 2 way unit so only one is needed for a pair of 2 way speakers.However two stereo amplifers will be necessary.
    2. Aside from getting more power, will I get better results from an active crossover vs. a passive crossover that uses Mills and Soniccaps?
    My experience has been that a properly configured active crossover will show improvements in the areas of dynamics /transient response,lower distortion and improved detailing/clarity.However as I have stated previously the active crossovers response must be precisely tailored to the drivers in a particular system if the improvements mentioned are to be fully realized.

    PolkMaster1 wrote: »
    I guess another question that comes up, would it be better to use film caps over electrolytics for an active crossover?
    Generally precision 1% metal film resistors and close tolerance small value film caps (ie.polypropylene ,polystyrene or polyester)are used to set the frequency points of the crossover filters.
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  • F1nut
    F1nut Posts: 50,654
    edited March 2011
    You cannot use an active crossover with SDA's. If you want to improve the sound of your SDA's further, buy some better gear to drive them with.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    F1nut wrote: »
    You cannot use an active crossover with SDA's. If you want to improve the sound of your SDA's further, buy some better gear to drive them with.
    I didn't see where he was reffering specifically to SDA's but I guess that might be a valid assumption after reading his sig. While my comments were in reference to a standard two way an active crossover certainly could be used aleast with certain SDA's.But as I have stated previously would not be as simple as removing the passive network and using any off the shelf active unit.To do it correctly would require some re-engineering, otherwise the results will likely be less than satisfactory.With that in mind I agree the better/simpler option would be to upgrade the components upstream.
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  • heiney9
    heiney9 Posts: 25,197
    edited March 2011
    F1nut wrote: »
    You cannot use an active crossover with SDA's. If you want to improve the sound of your SDA's further, buy some better gear to drive them with.

    This is the best advice for getting more from your SDA's if you've already done the x-overs and tweeters. The positive difference from using a better source, amp and pre-amp, in my case, has yielded improvements beyond what I thought was possible.

    Don't forget that all important SYNERGY.

    H9

    P.s. Don't forget cables too
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • aboroth00
    aboroth00 Posts: 1,106
    edited March 2011
    heiney9 wrote: »
    This is the best advice for getting more from your SDA's if you've already done the x-overs and tweeters. The positive difference from using a better source, amp and pre-amp, in my case, has yielded improvements beyond what I thought was possible.

    Don't forget that all important SYNERGY.

    H9

    P.s. Don't forget cables too

    Don't forget treating the room!
    2Ch Tube Audio Convert
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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    aboroth00 wrote: »
    Don't forget treating the room!
    Agreed, since I'm of the belief that the room along with the speakers are the most important components.Personally properly treating the room would take presidence over upgrading cables etc. as it would IMO yield greater sonic gains.
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  • PolkMaster1
    PolkMaster1 Posts: 847
    edited March 2011
    Hello all -

    Thanks all for the advice. Yes, we are talking about SDAs that I have - SRS1.2TLs. My gear is pretty good - driving them through amps, but I figure if I want to get more out of it, to try and take it another level, why not go bi-amp. I read that going "bi" wont amount to much if you still use the passive crossovers inside the speakers. I didnt know that the 1.2TLs cannot be bi-amped with an active crossover.
    Statistics show that 98% of us will die at some point in our lifetime.

    The other 2% will work for WalMart.
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  • PolkMaster1
    PolkMaster1 Posts: 847
    edited March 2011
    Forgot to mention -

    I also have quality speakerwire and cabling. Sound wont mean much without quality wire!!!
    Statistics show that 98% of us will die at some point in our lifetime.

    The other 2% will work for WalMart.
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  • FTGV
    FTGV Posts: 3,649
    edited March 2011
    PolkMaster1 wrote: »
    I didnt know that the 1.2TLs cannot be bi-amped with an active crossover.
    It would be totally impractical to try and emulate actively the filter networks connected to the 4 tweets in your 1.2's that create what I believe Polk referes to as "Progressive point source". Otherwise the basic high and low pass crossover functions could be done actively.But this best left to someone proficient in active filter design and with the ability to do accurate frequency response measuements.Aswell the big 16mh inductors would have to be retained.

    Some of the simpler models with the single tweets (like the 2B) are the most practical for conversion to active biamping.
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