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Thread: Martin Logan Monoliths (Series I or II)

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  1. #1
    Join Date
    Jan 2018
    West Des Moines, IA

    Default Martin Logan Monoliths (Series I or II)


    I am a new member to this forum (was directed here by Martin Logan office) and have a couple questions.

    I'm the original owner of a pair of Martin Logan Monoliths that I purchased over 30 years ago. They are still running strong! Not sure if they are series I or II. I think they are II's. Definitely not III's.

    Recently I moved and have a couple questions.

    I have a high-end Velodyne servo subwoofer connected to the system. I have forgotten the high-pass frequency setting I should use on the subwoofer.

    Also, I don't know the impedance of the speakers themselves (new amplifier and need to set impedance properly).

    Can anyone help?

    Thanks much!

    Tom L.
    West Des Moines, IA

  2. #2
    Super User Brad225's Avatar
    Join Date
    Dec 2006
    Wesley Chapel, Fl


    Welcome to our group Tom.

    I am sure Jonathan ( JonFo ) will see the post and be able to help you. He is a long time Monolith owner and DIYer/Electrical wiz.

  3. #3
    Super User JonFo's Avatar
    Join Date
    Jan 2005
    Big Canoe, GA


    Hi Tom, to the MLO club

    30 years, wow. I thought I was a long-termer at 24 years of ownership, congrats.

    The Monoliths I or II (I'm guessing you have a II) have the same low-impedance most ESL's have, so if your amp has various impedance settings our output posts, pick the lowest one (e.g. 4 ohms). In the highest frequencies, the impedance will dip below 2 ohms.

    As for sub integration, I assume you have a Velodyne ULD series sub with the separate amp/crossover component, right? (I had two ULD-18's for 15 years)

    The default crossover settings in the ULD series was 85Hz and they have a fixed 12dB/octave (2nd order) high and low-pass slopes.

    Given the relatively shallow slope, that default works OK, as would lowering it 60Hz. But lower just means the old 12" woofer in the Monoliths would have to work harder and that might mess up the mid-bass.

    Mid-bass woofer to panel integration is the make or break thing in the Monolith, and all my experience (see my many, many posts here) show that the stock passive crossover is nowhere near as good as using a modern speaker processor. And if you use one of those, then updating your old woofer drivers is a piece of cake. However, that requires a level of cost, complexity and DIY not many are willing to tackle.

    I hope that helps. Feel free to Start new threads on specific topics if you'd like.

    System #45 (Monolith IIIx, Sequell IIb, SL3XC)

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