Bi-Amping with Active Crossovers - Pros and Cons

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

  1. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    Eva Cassidy, and a few other simple tracks are good to showcase a system. The real test is when the music is "busy" - like a full orchestra and chorus.

    But the real problem with a highly resolving system is that it is ruthless - great recordings sound fabulous. But bad recordings are revealed for what they are with all the warts revealed.
     
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  2. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Whether you are using a custom passive crossover or an active passover, it doesn't matter that much which option you select. The main thing is getting away from the original Altec frequency dividing networks.

    Since you are basically working with two separate speakers, you can effectively set the crossover point anywhere you want from 500-Hz. to 1,200 Hz. Using 500 Hz. as the crossover point will give you a smoother but more pronounced midrange.

    This part is a bit puzzling to me. Initially, you felt the A7 sounded fine without the addition of a subwoofer, OK.

    But then after you add the sub, you cross it over at 56-Hz. This is about 10-Hz. higher than the 828-bass cabinets -3 dB. point. I find that the cabinet does go lower without really cutting out the bass. I find that my sub integrates perfectly at 40-Hz.
     
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  3. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Vocals and other midrange rich material is where the Altec’s really shine.

    I don't think I ever felt that they reproduced the feeling of being at a live orchestra.

    However, if you are reproducing a recorded orchestra that is played back through a movie theaters sound system, then the A7's are excellent in reproducing that same sound. You can listen to the Star Wars recording and reproduce it like you would hear it in a theater with an excellent sound system.
     
  4. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    Stereo reproduction is of course an acoustic illusion. It is nothing at all like a live concert, orchestral or otherwise. Recognizing that, it is a very persuading illusion!

    Whenever I go to a live orchestra or opera, I close my eyes, and try to analyze the sound as if it were a hifi system. Usually "Imaging is lousy" "Treble sounds rolled off". In fact Wagner, when he specified the Bayreuth Festspielhaus arranged the orchestral pit to play out of a narrow slot at the front of the stage to deliberately produce a diffused sound so that the singers had prominence.
     
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  5. Randoms

    Randoms Aerie Faerie Nonsense

    Location:
    UK
    Eva Cassidy is deservedly, popular demo material.

    Where / how do you mic an orchestra and chorus? I honestly believe that even the very best Hi-Fi systems (whatever they are and I won't add, obviously active) with recorded music comes nowhere near live music and to be honest, who could live with an orchestra and choir in their home? Just gently hitting a snare, the same model as my avatar in my lounge shocked a few people and the power of a few people singing at full volume comes as a surprise to many.

    Yes, a highly revealing system can be brutally revealing of poor recordings, but hopefully those poor recordings contain some fantastic music and playing, which a revealing system allows you to appreciate better. If a "better" system doesn't make musicians appear better than in a less revealing system, even on a poor recording, is that system actually better?

    I've always had problems when people say my system is so good, I can only listen to these ten albums!! Surely you want every album to be better, at the least in some area?
     
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  6. Randoms

    Randoms Aerie Faerie Nonsense

    Location:
    UK
    Just posted my reply above before reading this: absolutely spot on!!
     
  7. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    A single trombone going full beans can produce 115dB or more at 2 metres. That is not a transient - that is what you get when the music direction is fff. There is no audio system that can produce those levels (other than large horns) - and that is for a single instrument. And orchestral musicians during rehearsal and performance will be subjected to 95-98dB for 8 hours typically - often from their own instrument. Players frequently suffer long-term hearing damage.

    A good friend was an orchestral flautist, and his hearing in one ear is very dull. He reckons that it wasn't the flute that was the problem - it was the much higher pitched piccolo.
     
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  8. Funky54

    Funky54 Coat Hangers do not sound good

    Dear Lord in heaven…. Are you married or single? Forget the controversy of bi-amping and crossovers… tell us oh great one of your negotiation techniques. I could do the same thing, set up just like yours on my last day of marriage.
     
  9. SandAndGlass

    SandAndGlass Twilight Forum Resident

    When you are at a live concert where you are listening directly to a live orchestra, you are listening to a large number of instruments. Each of these instruments are very complex with regard to their tonality and the frequencies they produce. Having a speaker with two or three drivers cannot be expected to recreate this level of complexity.

    That level of complexity isn't likely to even bee there in the source material in the first place, for the same reason.

    How can a limited amount of microphones be expected to handle this complex information? Then somehow this information is expected to make its way into and be inscribed inside a tiny vinyl groove. This information then must be extracted by a single thin diamond that vibrates a shift, causing a wiggle up inside the cartridge body...

    So much of this glorious critical information has been lost long before it ever gets to the speaker in the first place.

    Regular non-horn speakers not only have difficulty reaching the high SPL's of an orchestra but it takes very high sensitivity speakers to reproduce the shear dynamics.

    The less complex the source itself is, the better chance it can be successfully captured, the better any speaker has the chance of reproducing it.

    In a movie theater or amplified venu, what you are hearing is the result of the full capture and sound reproduction process, to the extent that technology permits.

    Altec’s are pro-sound, they are the speakers sound does come out of in theaters and concert halls. By bringing them into the home, modifying and upgrading them, you truly have a speaker that has the accuracy, together with the ability to reproduce both the dynamics and SPL's of a live amplified concert event.
     
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  10. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I wasn't sure what you were getting at there. But yes, happinesses is where it's at!
     
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  11. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I forgot to respond to the video. Holy cow. Maximum Hair Excursion (MHE) is not an outcome I'm after. It certainly would have been amusing in high school though!
     
    Last edited: Jan 22, 2022
  12. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    For sure, but it's a rare audiophile that reaches even contentment for very long!
     
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  13. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Thanks for that link. Adding to the list of options to consider...
     
  14. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    The SPL might be very high at 2 meters, but nobody records an orchestra at 2 meters distance. The best seats are much farther out where everything is more integrated as a whole.
    A speaker with 90db efficiency requires a little over 1kW power to reach 120db, which is painfully loud. If you are using a pair, that's more like 500 watts. I guarantee that nobody is typically listening at these levels, and an orchestra is not reaching them.
     
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  15. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    This is awesome. Reality has lousy imaging and rolled-off treble! This post has the potential to lead to a very interesting thread of its own.
     
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  16. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    This next tweak is the last one I'll ever make...
     
  17. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    I think too many are used to hearing "hi-fi" and don't know what real live music actually sounds like. It's not that it is rolled off live, or images badly. It's that we are used to over-exaggerated treble and having a highly engineered soundscape or mic position that is highly optimized.
    I was listening to the system of a friend of a friend once, and we were talking about the subwoofer in particular. It was a servo subwoofer and was extremely clean. My friend commented that it needed to be turned up, while his friend and I were in agreement that it was just so clean that we weren't hearing all of the typical low-order distortions that usually bloat the bass sound.
     
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  18. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    famous last words, lol. I've been there!
     
  19. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I'm kidding of course. I think what I'm after is this: "Wow, after all that I've settled on something that I absolutely love." Then I sit back and enjoy. Eventually curiosity will creep back in and I'll be wondering about changing this or that. I'm definitely NOT interested in endless tweaking and experimenting. I'm also interested in a system that fits within the context of my living space. And so there are space limitations and aesthetics that limit where I can take this. And $$$ limitations.

    Also as @TheVinylAddict knows I've got a turntable plinth to finish building! And then after that? A car rebuild with my daughter that will take a long time. So this active crossover/bio-amping business has a lifespan to it.
     
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  20. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    Are you still looking to take a passive system, remove the crossovers, and build an active crossover for it? You know, if you're really set on doing this, there are ways to make it easier, and more obtainable without custom filters, if you choose your drivers very wisely.
     
  21. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Yes, I'm really set on doing this. And I see this as an experiment worth trying to do very well. I don't know whether I'll like it or not. It may be that when all is said and done I decide that I'm happiest sitting that little Marantz 1060 + two-way KLH 6s in my living room. If the bi-amp proves too complicated, too cluttered, and doesn't CLEARLY sound better? It's gone. I'll sell the stuff I don't need, sit back, and be quite pleased knowing that I don't have to spend a bunch more money to love what I'm hearing. (I already know that of course.)

    And if I do love the outcome? I'll be glad I invested the time and energy to get there. There is no one right answer. For me, it seems like a win-win to go through this process.
     
    Last edited: Jan 22, 2022
  22. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    This is a different approach I've been wondering about actually. Choosing drivers wisely could mean no padding, minimal crossover network, etc. But then we're into the world of speaker design. So if I went this route, I'd probably need some tried-and-true DIY blueprints to work off.

    Of course, I could go to single full spectrum drivers as well. No crossovers needed. But I'm not sure that's going to get me where I want to go as far as full spectrum reproduction. (Noting that I’m pretty sure I can’t hear beyond 15 kHz at 47…)
     
    Last edited: Jan 22, 2022
  23. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    What I was getting at is that there is an easier way to guarantee a good outcome. I'll present a simple method that could work for you:
    1. Base the system around a GOOD full-range driver or extended range midbass with a flat and extended frequency response. Avoid drivers with large breakup nodes unless they are a couple octaves from the intended crossover frequency. Don't go too large in diameter (4"-6-1/2"). Use a driver that can reach at least 8khz without rolloff.
    2. Using 4th order Linkwitz-Riley slopes for all drivers, crossover to a tweeter (also having a flat and extended frequency response- especially having a resonant frequency down around 500-800Hz) in the 2-4 Khz range. Use 13560/(full range driver diameter in inches) for a guide on where the full range driver will start to beam and cross over at that frequency or, preferably, lower. This can be pushed somewhat, but for the best dispersion it's good to follow this rule.
    3. Cross over to the woofer in the 200-400Hz range. This should allow for most woofers to be used, as they generally will reach 800hz flatly before any breakup regions.
    4. Use adjustable all-pass delay networks on the midrange and tweeter. Starting with no delay and working in pairs (woofer- mid, then mid-tweeter), reverse the polarity on the higher frequency driver and play a tone at the crossover frequency. Using a sound meter, begin to add delay until you get the deepest null. Set the polarity back to normal on the midrange, and do the same with the mid and tweeter. This should get you in the ballpark for phase tracking between drivers, as there should be a deep null at the crossover frequency when they are out of phase.
    5. using a test tone that is between the crossover frequencies, adjust the levels of each driver / amp to be matched.
    6. listen, and tweak it to personal taste.
     
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  24. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I love the template. So let me ask what you think about the aforementioned Infinity RS 1.5 in this regard. The mid-range driver is supposed to be truly excellent but I don't know if it presents the range you listed or where its resonant frequencies are at. And I have some TOTL Emits available to me as well. A couple different types better than the stock EMITS. I'm re-attaching the RS 1.5 specs here: http://www.infinity-classics.de/technik/manuals/RS_1.5_technical_sheet.pdf

    These specs don't provide enough detail for me to determine whether they'd fully satisfy your criteria or not. I could do more digging. But if these drivers are up to the challenge, the question of how to design the crossover is (if I want it to be) wide open. I'll note that I expect this script of yours - and my response - to lead to comments along the lines of "Infinity spent thousands of hours trying to get this right. And you think you can do better by tinkering in your garage? Please..."

    And for what it's worth, no I couldn't do this myself. But my speaker guy absolutely could and has done stuff like this already.
     
  25. OhioGraySky

    OhioGraySky Well-Known Member

    Location:
    Newton Falls, Ohio
    That's funny. I'm the same age, and have about the same high-frequency limitation. Years of playing in bands, industrial noise, and motorcycle wind noise have taken my HF away.
     
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