The Crossover

Discussion in 'DIY' started by mtoc, Mar 27, 2016.

  1. mtoc

    mtoc SBAF's Resident Shit-Stirrer

    Banned
    Joined:
    Oct 22, 2015
    Likes Received:
    84
    Trophy Points:
    28
    Hi folks, are the tradtional crossover (we ignore the orders here) still better than those Linkwitz digital crossover at most cases? If my speakers have many drivers (like, say 7 drivers per channel), if I choose the Linkwitz stuff I will need many amps (more than 4 I guess). If stick to the passive filters, well, maybe it's a little hard to design the crossover due to the number of the drivers...

    Edit: maybe it's 4-way-ed, 4 woofers, 1 mid-woofer, 1 midrange...
     
    Last edited: Mar 27, 2016
  2. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    Yes. Designing a 7-way speaker might be a little hard with analog passive cross-overs.

    That said, 7 drivers does not necessarily translate into a 7-way speaker. That's a bit crazy. You could have 4 woofers for bass, 2 woofers for mids, and a tweeter for highs. This AFAIK is usually done when you have narrow towers for space considerations.
     
  3. purr1n

    purr1n Burned out

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    81,288
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    The use of a digital crossover requires A-D D-A conversion, unless the digital crossover is also used as a DAC (this will require some ingenuity for an analog volume control). This means that the quality of any source, whether DAC, turntable, tape, will be limited by the quality of the digital crossover.

    My opinion is that A-D or D-A conversions inflict significant trauma to the music. Digital crossovers are good for prototyping speakers and building great mid-fi systems.
     
  4. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    Yes, conversion can inflict degradation to music. But analog cross-overs can also inflict significant degradation.
     
  5. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    For example. On a front end, some time ago I had a coworker design a 5th or 7th order analog Butterworth.

    In digital this is pretty straight forward. There are some quantization issues (depending on the number of bits), timing jitter issues, and stuff that happen due to conversion. But still, pretty straight forward.

    In analog, he could only guarantee the effective coefficients up to a point, higher order was out of the question, because if I remember correctly, the precision of the components could result in a possibly unstable filter. It was an active design, dunno if a passive design was feasible. Analog is sort of an art when you get down to it.

    On another design, I asked an analog design engineer to increase the order of the low pass filter of a charge pump to accommodate for a higher order delta sigma in a jitter attenuator. I was asking to go from 2nd to 3rd order. No cannot do. I was given a pretty grim picture of things going down to hell and risk increasing 10 fold or something. So I had to do some stuff to the delta sigma to meet requirements.

    Anyway, who knows. Maybe in audio it's much easier and less intrusive to do analog cross overs than digital.
     
    Last edited: Mar 27, 2016
  6. Serious

    Serious Inquisitive Frequency Response Plot

    Friend BWC MZR
    Joined:
    Sep 28, 2015
    Likes Received:
    2,052
    Trophy Points:
    113
    Location:
    near Munich, Germany
    :eek:
    I never liked the Gauder Berlina RC9 and RC11 with their 50db/octave x-overs when I heard them at shows. They always sounded really dead and lifeless to me.
    The Marten Coltrane Supreme II which use similar drivers always sounded much better to me with their 1st order crossover.
     
  7. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    A 1st order crossover, depending on application, maybe insufficient to reject signal that may be outside a driver's linear region. In other words, it can result in significant distortion.

    I have not heard the Coltrane Supreme IIs (not that I remember). But those are $480,000/pair from a quick interwebz search. That's more than my mortgage.
     
  8. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    BTW, I understand where The Merv is coming from. Multiple A-D D-A stages is probably not w/o penalties.

    One thing one could do is work directly with the bit stream with something like this:

    https://www.minidsp.com/products/ht-series/nanoavr-hda

    It may not be the most ideal solution because one is constrained by their D-A selection.

    Another approach is to use a computer and pick the appropriate D-A to one's preferences.

    The NanoAvr-HDA does not seem to bad at least on paper. They are using half decent DACs and stuff.

    Anyhow. I might in the future give their solution a try. My AVR is giving the ghost.
     
  9. purr1n

    purr1n Burned out

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    81,288
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    83 piece 4th order passive XOs destroy the essence of music. First order x-overs are good if the drivers are well behaved past the XO region. Otherwise, the roll-off won't be good enough to kill severe peaks. Some of the Accuton drivers used by Marten are amazing in that they exhibit excellent wide band behavior, and decay quickly and cleanly like metal drivers. It's very difficult in apply first order XOs - they are only suitable in specific instances.

    Lower order XOs help integration and cohesiveness, but can have super screwy off-axis behavior. Higher order XOs sound more precise (let the tweeter or mids do more of the things they are good at), have less strange lobing effects, and kill resolution and immediacy. What it comes down to is balance. Too loose and you end up like senile Yoda and the universe turns into shit. Too hard and you end up like the Emperor and the universe still turns to shit.
     
  10. OJneg

    OJneg The Most Insufferable

    Friend BWC
    Joined:
    Sep 25, 2015
    Likes Received:
    3,900
    Trophy Points:
    113
    Location:
    Grand Rapids, MI
    Why are you building (or thinking about building) 7-way speakers? What makes you think that's a good idea?

    Active crossovers are always going to be a compromise. Stick to the playbook people. 2-way and 3-way, 4-way maybe if you consider the subwoofer. Simple 2nd order slopes are the best compromise when you weigh in sonic fidelity. Of course 1st order is going to be better, but might just not be possible without discerning driver selection and foresight. Show me an active solution (analog or digital domain) that's more musically transparent than a quality coil and decent film cap.
     
  11. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,920
    Trophy Points:
    113
    Location:
    Irvine CA
    I think I understand what you are saying OJ. But like you alluded to, sometimes some drivers, or set of drivers which do somethings really good, require a little more than a quality coil and a decent film cap to perhaps sound their best.
     
  12. Josh Schor

    Josh Schor Friend

    Friend
    Joined:
    Jul 13, 2020
    Likes Received:
    388
    Trophy Points:
    63
    Location:
    Ann Arbor Mi
    Here is a pic of the crossover in my speakers. I would like to add bypass caps as rebuilding it is way beyond my skill level. Can anyone unnamed.jpg tell me where they would go?
    best,
    Josh
     
  13. purr1n

    purr1n Burned out

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    81,288
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    Don't "bypass" or parallel caps. Bad results with speaker xovers. Replace the generic yellow caps, concentrate on caps for the highs.

    Pretty good or decent cap > generic cap bypassed with the best bypass cap.
     
  14. Pancakes

    Pancakes Friend

    Friend
    Joined:
    Aug 13, 2020
    Likes Received:
    1,049
    Trophy Points:
    93
    Location:
    Atl
    From the looks of it, that's a 3rd order filter in the mid/bass. Coil, cap, coil vertically on the left side of your picture.

    The tweeter network is on the right side. Hard to tell exactly what's going on without seeing the traces but it's either a 2nd order (cap, (3 yellow caps act as one), coil) or 3rd order (cap, coil, cap). Not sure what the black thing top right is - cap? resistor?
     
  15. Josh Schor

    Josh Schor Friend

    Friend
    Joined:
    Jul 13, 2020
    Likes Received:
    388
    Trophy Points:
    63
    Location:
    Ann Arbor Mi
    Would Jantzen Alum z-caps and Dueland or Mills resistors do the job? would I still use bypass caps? sort of expensive but the speakers are worth it I think.
     
  16. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    3,381
    Trophy Points:
    113
    Location:
    The Netherlands
    Ordered some parts for an active analog crossover to have a play with. With my speakers i already played with this in the digital domain and the results were very favorable having a hpf relieving the mains from any sub bass.
    Got a kit with modules for 80 90 and 100hz, since i have stereo subs there should be no problems with localization.
    From here: https://www.xkitz.com/collections i got the 2 way balanced boards and psu.

    All i need now is a case, i was thinking of getting a 1u case with D style holes for xlr but i need to check the spacing of the connectors on the pcb's first. There are some prefabbed ones but you can also design your own 1u case panel here which is cool: https://www.pennelcomonline.com/en/Panel-Designer-Retail---UK-and-ROW/cc-162.aspx
     
  17. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    3,381
    Trophy Points:
    113
    Location:
    The Netherlands
    The crossover arrived and is working great, went with a 1u case i did a bit of a hackjob on but out of sight out of mind. This thing is really transparent and with the hpf on the mains even if there was some reduction in transparency the lower distortion really is more noticeable. Also the better integration with subs because of the 4th order filter just took everything up a couple of notches as well.
    Have a dip at 100hz cause of some room fuckery so i put the crossover there and it actually filled it in substantially! Also this high puts the port tuning of the mains well away and it should really not be much different than integrating some acoustic suspension speakers.

    Happy guy looking for a new project…
     

Share This Page