Bi-Amping with Active Crossovers - Pros and Cons

Discussion in 'Audio Hardware' started by Soundgarden, Jan 9, 2022.

  1. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    A sub-conversation popped up on a different thread about active bi-amping. Instead of trying to continue it there, I figured I'd pursue a separate conversation. I'll premise this by stating that I've never bi-amped before and I'm not an an engineer. I'm trying to understand the key ingredients for success at a fairly general level.

    The sort of setup I'm interested in is where an active crossover is placed between a pre-amp and two power amps - one power amp to drive the lows, the other to drive the mids/highs. Of course the speakers need to be bi-ampable.

    What are the pros of active bi-amping compared to passive bi-amping? From what I can tell, in active bi-amping each amp is required to accomplish a more limited, less energy-intensive task. More specifically each amp receives, amplifies, and delivers only a portion of the frequency range. This completely separates the low frequency signal from the mid/high frequency signal, avoiding potential interference between the two and increasing headroom. In passive bi-amping, each amp still receives, amplifies, and attempts to deliver the entire frequency range... with the passive crossover in the speakers having to bleed off a bunch of wasted energy as heat.

    What are the cons? Near as I can tell, this has to do with ensuring that the active crossover is tuned to the right frequency, with the right roll-off rates, and can ensure that the gains are matched. If those things aren't correct, one may have accomplished the pros, but replaced a crossover that's tuned to the speaker with one that isn't. (Let's assume that the quality of the active crossover is also very high and we're not talking about dropping a new component of questionable quality into the signal path.)

    Is this about right?
     
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  2. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    Good topic, on that note, I'll be lazy and offer something on the topic I typed recently on a different thread: Canare 4s11G. Is there a better cable?

    I've never attempted active bi-amping on my own system though, but have "true" passive bi-amped a couple of times. But I'd love to learn more about it from others with experience.
     
    Last edited: Jan 9, 2022
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  3. Davey

    Davey NP: Carmen Villain ~ Sketch for Winter IX: Perlita

    Location:
    SF Bay Area, USA
    If talking about using a set of commercially available passive speakers, you'd need to open them up and rewire to bypass the internal crossovers. To do a good job, you would have to model the drivers and determine optimum parameters for the crossover, then know how to implement those parameters in a line level circuit to use between preamp and amps. And you generally need some type of protection for the tweeters during power on, and in case of any amplifier connection "mishaps".

    I've designed and built my own 3-way active system in the past, and used it for a few years, it can sound very good, but you do need a pretty good understanding of speaker and circuit design to do it successfully unless buying a complete kit where someone else did all the hard work. And it does add a bunch of circuitry in the signal path, so that can really degrade the sound if not careful.

    One can implement simple passive crossovers between preamp and amps too, though you are generally limited to second order slopes, and it gets a little complicated to do much response compensation, but can sound much better than a typical active crossover implemented with a bunch of opamps.
     
  4. Tim 2

    Tim 2 MORE MUSIC PLEASE

    Location:
    Alberta Canada
    I tried bi-amping with electronic crossovers many years ago. The system was very complex, many extra cords and cables etc etc. The more cables and boxes the signal goes through the more it's degraded.
    After a coupe years I felt I wasn't really gaining anything sonically and went back to one good pair of speakers and one amp.
     
  5. Uglyversal

    Uglyversal Forum Resident

    Location:
    Sydney
    You do have the basic idea right, I have tried myself and I have to agree with Tim 2. Under some circumstances, specially in a professional system could be very useful despite having the same shortcomings I am going to mention but is basically what Tim said.

    The more boxes and cables the more the signal gets degraded. A big advantage of an active crossover is that on the fly you can adjust parameters to your taste and limit the work the amp has to do reducing distortion.
    The big disadvantage is most crossovers will degrade the signal way more than what I consider acceptable. A lot of them are also digital so you can kiss goodbye a full analogue system, if that is of importance to you but my main concern is the sound.

    Then you have the extra amp/s and cables that will add to the cost substantially. When you consider the total cost of the set up, and the problems you introduce, I think you are much better off spending the money in better equipment and cables than on complicating your setup. Still, if you can, it is fun to try, I wouldn't bother with passive bi-amping.
     
  6. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I might be in over my head on this one. But I have an amp builder with quite a bit of experience building custom line-level crossovers with all analog components and a master speaker builder who understands the speaker side of bi-amping. They don't know each other though!!!

    I'll admit I'm very leery of putting a whole bunch of active electronics between my pre-amp and power amp/amps.
     
  7. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    So active bi-amping or no bi-amping then... with active bi-amping possibly being a huge headache and mixed results. That doesn't sound very fun. One reason is that I'd be relying on others to better understand and execute this. I'm going to keep looking into it. Sounds great in theory but like a can of worms in reality.
     
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  8. misterdecibel

    misterdecibel Bulbous Also Tapered

    The main thing about a crossover network, whether it's passive or active, is that the response of the raw loudspeaker drivers is part of the filter. So the crossover has to be designed for those speakers in that box.

    If you're using an off-the-shelf active crossover to "activate" a speaker that was designed with a passive filter, you will be throwing away all the work the engineers did and starting from scratch with a generic solution. You'll probably end up with several major peaks in the system response. Some people find that sound "exciting" at first.

    "Passive biamping" is just a stupid idea period.
     
  9. Uglyversal

    Uglyversal Forum Resident

    Location:
    Sydney
    I've lusted over the idea since the mid 80's when a friend had it on a large system and indeed sounded good then. As you've said, it is great in theory but my personal experience is that I am better off without it. I am not saying that if someone came and listened to my set up when I had it would have thought it sounded bad, but I certainly prefer it without it. The less in the way of the signal the best things sound for me.
     
  10. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    I've always viewed it as that bi-wiring will *most likely* be a waste of time, and passive bi-amping *might* be a waste of time. :)

    I've heard examples of where a passive bi-amp did help.... but in all cases it was on a fairly high end amps and speakers.
     
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  11. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    If I can get my two experts to talk to each and devise a solution without charging me it might be worth trying! I definitely don't have an interest in trying to tune an of-the-shelf crossover for the reasons you've mentioned. That honestly sounds like a terrible idea after spending time and money to buy and restore components that I adore.
     
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  12. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    Hey, I didn't realize you were in Bend, Ore for some reason I thought you were overseas... (funny what happens when you actually pay attention and read! :)) I'll be passing through soon I love the drive though N Cali and the S parts of Oregon...
     
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  13. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    As always, I love how you're not easily knocked off course from trying things!! :)
     
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  14. House de Kris

    House de Kris VVell-known member

    Location:
    Texas
    I haven't had passive crossovers in my main system since the 70s. Some may say, and have said, that additional electronics for the signal to pass through is detrimental. But, in my opinion, it is far less detrimental than passing the signal through the passive crossover. Passive crossovers are the primary limiting factor to loudspeakers. Ditch them, and the sound opens up immensely.

    Over the years I've developed some rules about designing passive crossovers. Number 1 rule is: don't use passive crossovers.

    Using active crossovers is certainly the easiest way to breakthrough to the next level of system performance. But, this is certainly a personal choice. It's based on how important quality reproduction of music in the home is to you. Me, I love music and enjoy it being reproduced in an effortless style. Hence, it's a no-brainer to go the active 4-way (also called tetra-amped) system.
     
    Last edited: Jan 9, 2022
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  15. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    Can you share any pics of what the finished work looks like??? I appreciate that you've done it... :)
     
  16. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I appreciate that. Although I've been stalled out on that custom Micro Seiki turntable for a while. I decided to build a 1000 gallon pond in my backyard about the same time. Now the pond's done and the yard is frozen for a few more months so my excuses are wearing thin.

    [​IMG]
     
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  17. House de Kris

    House de Kris VVell-known member

    Location:
    Texas
    I'd love to. Alas, stevehoffman.tv does not host pictures.
     
  18. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    That is awesome... :) Moreso because I bet a donut most of that work was done with your hands / back!
     
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  19. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
  20. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Two power tools were involved: A drill motor to mix a zillion bags of mortar/concrete; and an angle grinder to cut some texture in the rock the water flows over. Literally everything else was done with my hands/back!

    I'll do the finish landscaping this spring. Which will be a breeze compared to the work to date.
     
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  21. House de Kris

    House de Kris VVell-known member

    Location:
    Texas
    I got a Flickr account just so I could share photos here. Unfortunately, something has gone haywire and I can no longer access Flickr. So I dont. Too much hassle. And this site, pretty much unique in the forum world, stopped hosting photos years ago. I can take the hint, no photo sharing here.
     
  22. TheVinylAddict

    TheVinylAddict Scientist's have opinions too

    Location:
    AZ
    I'm the kind of guy who also notices the silly things too, like the extra time taken to half lap the corners of the planter box, the impeccable maintenance on that fence, what looks like decent tires on that dolley :)
     
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  23. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    The tires! Hah. Also the thing behind the pond is a bocce court made of decomposed granite and crushed oyster shell. Perfectly level. My experience there with the oyster shell actually led me to suggest it in another post as a better alternative to nesting one's turntable in a sandbox...
     
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  24. Brother_Rael

    Brother_Rael Senior Member

    Location:
    Scottish Borders
    You'd be better off keeping your speakers as-is but instead investing in some good actives. The active biamping thing (IMO obviously) is a DIY halfway house to getting to the active speaker, which is the ideal goal. Actives will reduce distortion by orders of magnitude passives can't begin to dream of.

    If it's a fun project and something that you want to give a go *as a fun project* then have at it.

    If, however, you want to experience actives speakers, just buy active speakers.

    Relatively speaking, there are plenty of options out there (not as many as passives, but the domestic audio market has traditionally been geared up to source - amp - speakers for decades). My first pair were Acoustic Energy AE22s, which I bought direct from AE a few years back. I will be honest and say I was utterly astonished by how good they were. Nothing I'd heard in the price range, or at a good few points well beyond it, came remotely close to what I heard and to reproduction of that standard that day. I've heard many many systems over the last 40-odd years, been to the hifi shows in the past and sat in hifi shops listening to systems costing £thousands but none made me sit up and take notice like this.

    And they clocked in - at full price - at £900. Astonishing. When you get on to models from Event Audio, Dynaudio, Genelec, Mackie and plenty of others, you're spoilt for choice. I wouldn't go back to passives. Not through some evangelical speaker preference, simply the quality step-up was apparent in even modestly priced speakers.

    I appreciate that many audiophiles feel that they want to choose their amp to go with their speaker, not have the active speaker designer/manufacturer make that decision. I see that as a pretty self-limiting decision if I'm brutally honest.

    There are many ways to audio nirvana these days, more than we'd ever given credit for than when I first started in this hobby in the late 1970s. Actives are one way, others will find their preferences through other means. The days when audiophiles contemptuously dismissed actives as "desktop computer speakers" are well and truly kicked into the sea however. Rightly so.
     
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  25. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I appreciate you putting this out there. Question: Can you offer any examples of what you'd see as a good active crossovers?
     
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