The Ultimate Monitor 70 Active Crossover Multi-Amp Project



  • Cybershaman
    Cybershaman Posts: 44
    edited November 2012
    I need to post when I'm more awake rather than just before bed. Less "posty" that way... ;)

    I also used Dayton Audio Silver Solder. (

    To be fair, since the gain on the tube amps was low, I had to equalize the levels with the first XO's trim pot. I'm proud to say that my ear was pretty close since I barely adjusted after I received the OmniMic software.

    Since I can program the XO I am using for the high-end, I might take advantage of the 18db/octave slope and try to drop the tweeters down a little lower. I'll have to fully test one of them again with the Dayton Audio DATS system in an effort to find their resonant frequency. We'll see...

    Because I am a bit limited in what I can do with my existing active XOs, I am actually seriously considering getting the 3/4-way miniDSP crossover ( from the company that EndersShadow pointed me to. (Thank you, sire!) I'm thinking that it will be indispensable for any future speaker projects...

    OK, I THINK that's it. Now I can get back to other things... ;)
  • sponger
    sponger Posts: 325
    edited November 2012
    And the active crossovers are 18db/oct...

    Tweeters: 2.4k high-pass
    top 2 woofers: 2.4k low-pass
    lower 2 woofers: 800 low-pass

    Were those the original passive xover points?
    Denon X7200WA
    LSiM 705 703 704c
    Denon DP 400
    Yamaha CDC 775
  • Cybershaman
    Cybershaman Posts: 44
    edited November 2012
    While the high-pass was clearly stated in the product info as being at 2.6k (12db/oct) the lower one took some sleuthing. From what I gathered from various hints, rumors and pure guesstimation, it could be anywhere from 700 to 800 Hz or so. The active XO in the AudioControl Richter Scale I am using is hardwired in and selectable for only 100 or 800 Hz so there is really no particular reason that I am using that XO point other than the fact that I lucked out in that it was close enough to what I thought it could be.

    Now, having said that, I anxiously await the miniDSP 4x10 Hd ( unit I ordered. While the XO in the AudioControl Phase Coupled Activator* is "programmable" in the sense that I can change it by soldering some resistors to a DIP header (, I think it will be best to wait. Especially since I want to try out the vaunted 24db/oct slope of the Linkwitz-Riley class filter. That should take the fun to the next level...

    For what it's worth, I've noticed that some people have looked for data on particular drivers and have had a hard time finding it. So, I'll be using the Dayton Audio DATS test software on several different Polk transducers here in the coming weeks and posting the results. I'm curious how low I can get these tweeters to go... :twisted:

    * The practically antique Phase Coupled Activator is the "secret weapon" in my Home Theater system. Originally, it was one of the "new" digital processors that "reconstructed" the lost bass in many "toned down" vinyl recordings and even some CDs and video tapes. It does this by halving the bass signals and then inserting the results back into the analogue audio stream. While now days (shoot, that thing came out in, what, the late 80s?) you rarely come across such bass deficiency in recordings. However, where that subtly added extra impact comes in handy is with movies! Since it isn't merely boosting the bass it adds that certain je ne se qua that people always comment on when they come over. It works out even better in 5/7.1 surround systems because while it has a tendency to add unwanted bass to low male voices, that isn't a problem when a center channel is used since most if not all of the dialog isn't present in L/R signal! I also use it instead of Loudness for low level background listening. If you are in any way a Home Theater enthusiast I can't recommend one enough. I only recently reacquired one after having sold my original one years ago when I went on "walkabout" as a spritely younger man. They seem to be available from time to time on eBay for around 200 bucks. :cool:
  • txcoastal1
    txcoastal1 Posts: 11,680
    supernut wrote: »
    supernut wrote: »

    I agree with some of the previous comments , here my advise to improve monintor 70 , factory crossover is fine , add a additional 4OHM tweeter IN SERIES with current tweeter , fasten to the top of cabinet.

    Wow on the forum for 1 day, you must be an expert
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
  • pitdogg2
    pitdogg2 Posts: 18,745
    supernut wrote: »
    supernut wrote: »

    I agree with some of the previous comments , here my advise to improve monintor 70 , factory crossover is fine , add a additional 4OHM tweeter IN SERIES with current tweeter , fasten to the top of cabinet.

    Quoting your own one word comment.... Seems like I've seen that recently.
  • nooshinjohn
    nooshinjohn Posts: 22,945
    Perhaps reaching out to Ken pre-emptively would be a good idea.
    The Gear... Carver "Statement" Mono-blocks, TriangleArt Reference SE with Pass Labs Xono Phono Preamp, Walker Precision Motor Drive, ClearAudio Goldfinger Statement V2 cartridge and Origin Conqueror Mk3c tonearm, Polk Audio "Signature" Reference Series 1.2TL with complete mods, Pass Labs X0.2 three chassis preamp, PS Audio PerfectWave DAC MkII, Pioneer Elite SC-LX701, Oppo UDP-205 4K Blu-ray player, Sony XBR70x850B 4k, Polk audio AB800 "in-wall" surrounds.

    “Every record has been destroyed or falsified, every book has been rewritten, every picture has been repainted, every statue and street building has been renamed, every date has been altered…History has stopped. Nothing exists except the endless present in which the party is always right” — George Orwell

    “If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
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