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Thread: Modifying the Odyssey crossover - my adventure

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    Default Modifying the Odyssey crossover - my adventure

    So I've been unhappy with the Summit X for a variety of reasons, I can't fit the CLX in my room, and I really like the O's... which led me here, exploring the possibility of upgrading the O's crossover, of this very worthy speaker. This is a continuation of this thread... the comments from other fellow mod'ers have been extremely encouraging.

    First off, the O's have rewarded me for over 9 years now, and have been the reason I spent so much money on the rest of the electronics. They do have their own limitations, which I am hoping to address with this mod. But they are sensational to boot. When did I first started thinking about this? Well, 9 years ago, when I asked the dealer - so what's not so high end about this speaker? Answer: the crossover.

    Attached to this first post is the crossover schematic; comments and pictures to follow...

    martin-logan odyssey crossover schematic.pdf


    Edit Dec 6, 2011: Attaching the woofers' specifications
    Odyssey-8-inch-driver.doc,Odyssey-10-inch-driver.doc
    Last edited by spectral; 12-06-2011 at 08:32 AM.
     

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    In this second post, I'll describe what I saw in the schematic... first off, two crossovers - one for the woofers, the other for the panel. Let's take the woofer xover first. You will notice there are two resistors in parallel (RX13 & RX14) giving a 1.5ohm impedance to attenuate the output of the woofers - this is actually related to the -3dB switch in the back of the speakers, and the switch is right above them in the diagram. If you look at the description of my system, years ago I plugged in a 50W Caddock resistor in series with the woofers to attenuate bass output even more, and have settled for 4 ohms for my room (the switch is at 0dB - bypass).

    Replacing the capacitors requires a lot of research... I posted before three main sites I have found useful, and here they are again... audiocircle, humblehifi and laventure. A lot of the mod'ers on the net play with capacitors in their tube circuits, so some of the comments they make relate to how capacitors sound in various pieces of electronics. This doesn't help when it comes to crossovers.

    The last link is the most helpful of all, though still subjective; but at least, they've tried the capacitors under test in various applications, from power supplies, to active amplification circuits and crossovers. This is a nice start. One thing stands out - you can't go wrong with Mundorfs and Duelunds; well, this is something I am already very familiar with, and these are the choices of most true high end manufacturers - and then this web site put the stamp on it; this is all I needed to get me going...

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    Part three, and it's time to look for replacement capacitors... partsconnexion.com and madisound have them all (madisound is a little cheaper). So then I read up on Mundorf's web site - the MXT's are to be used as the parallel-to-the-woofer capacitor, while the MXP's for midranges - notice those two 100uF and 170uF caps in the woofer xover that run parallel to the woofers.... this would be the first testing ground for me.

    To make a long story short, MXT is out of the picture, and manufacturers appear to use MXPs for their woofers, so I order the 100uF for the rear woofer. Bingo... tests with warble tones prove that the woofer that has the mod sound cleaner than the corresponding un-mod'ed one in the other speaker. We are off to a good start...

    But how do you get to the crossover? Well, just detach the rear panel carefully, and the panel's crossover is looking at you; the woofers' is on the opposite side and you need to take off the front woofer to access it; but once you do it's easy to work with that crossover.

    And what do I see? Those woofer capacitors are electrolytics. Really? REALLY? And I paid so much money for these speakers? Clearly, a product made to a price point, and the crossover designed to just fit nicely in the enclosure... but not high end.

    So next come the first pictures...

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    First off, the replacement of the 100uF electrolytic - the Mundorf MKP 100uF/400V (+-3 tolerance, better than the 250V version):

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    Next to it, you see four Mundorf M-Resist Supremes; they are 1.5ohms each, arranged to give me two 3-ohm resistors in parallel, i.e. what the schematic shows.

    Next, here's the capacitor installed to the right (notice the empty space where the electrolytic used to sit, and where the other 170uF electrolytic still is):

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    I LOVE point-to-point wiring

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    fantastic thread, spectral. Thanks for posting... I'm moving it to Tweaks section.
    Tom D'Acquisto
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    ML Owner from 1988 to 2015 (Sequels, reQuests, Summits, Cinema)
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    ick HERE to see my ML systems of the past.


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    Next up, the panel's crossover; to the right, I have already installed those resistors you saw above - not perfect for sure. Notice how ML keeps their resistors elevated to dissipate heat - nice! Theirs are 5% tolerance, mine 2% - no real difference. And they are both non-inductive types.

    Mostly Solens and one horrible Bennic - yikes!

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    Solens are good in power supplies, not crossovers. They are probably used here because of their high values and small size.

  7. #7

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    Quote Originally Posted by spectral View Post
    first off, the replacement of the 100uf electrolytic - the mundorf mkp 100uf/400v (+-3 tolerance, better than the 250v version):

    Name:  IMG_4271-2.jpg
Views: 4983
Size:  44.6 KB

    next to it, you see four mundorf m-resist supremes; they are 1.5ohms each, arranged to give me two 3-ohm resistors in parallel, i.e. What the schematic shows.

    Next, here's the capacitor installed to the right (notice the empty space where the electrolytic used to sit, and where the other 170uf electrolytic still is):

    Name:  IMG_4261-2.jpg
Views: 4466
Size:  45.6 KB

    i love point-to-point wiring
    good thread
    Last edited by Dan Osib; 10-03-2011 at 04:47 PM. Reason: INCORRECT INFORMATION

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    Default Selecting the capacitors

    So here's the conundrum... what do I buy? Mundorf MKP for the woofers is enough - they run parallel after all. The panel is more interesting... The uber-performing Duelunds VSF's cost something like $250-$500 each for the values we want. The Mundorf Supremes have more values to choose from, while the Mundorf Silver-in-Oil don't go very high in value (10uF max), they cost 4X the Supremes and are huge due to the very high voltage rating (impossible to fit in the cabinet).

    So for the high values we are after, the Silver-In-Oil's are cost prohibitive, for my wallet at least. Then I keep reading that they aren't really that much better than the "basic" Supremes, and a lot of people seem to think they tip up the treble (I don't want that either) - I really want to keep the excellent tonal balance of the Odysseys. I am thinking they'd be overkill for the O's and just plain wrong, at least in my all-Spectral system.

    So I have settled for the Mundorf Supremes with the Vishay 1837 or 1839 bypass capacitor - around $50 each for the values we want - for the panels. They are being shipped this week, to be installed over the Columbus weekend, so more to come later...

    But right now, a word on selecting the right replacement values - not all caps are available as a single piece - the 10uF 100uF are the exception. So here's the breakdown right now:

    1. 100uF woofer electrolytic -> 100uF/400V Mundorf MXP
    2. 170uF woofer electrolytic - 3x 56uF/400V Mundorf MXP
    3. 10uF panel -> 10uF/800V Mundorf M-Cap Supreme
    4. 13uF panel -> 2x 6.8uF Mundorf M-Cap Supreme
    5. 47uF panel -> 2x 22uF + 3x 1uF Mundorf M-Cap Supreme
    6. 51uF panel -> 5x 10uF + 1uF Mundorf M-Cap Supreme


    Only if the Supremes don't produce the improvement I am hoping for will I consider the uber-expensive Silver-In-Oil (and I'll need a lot of those). Finally, the VISHAY-RODERSTEIN MKP-1837 (or the axial version 1839) bypass cap will be used on a as-needed basis, by trial and error.
    Last edited by spectral; 10-04-2011 at 08:10 AM.

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    Have you considered Black Gate capacitors at all? I didn't notice any difference replacing replacing one of the caps in my crossovers with a Black Gate, but I did notice a huge difference doing so in a DAC that I used to have. They are now manufacture-discontinued and expensive, but Parts Connexion does have them in stock. BTW the difference was not immediately apparent. This was a case where I had dismissed the mod as having no effect, but then a few monthe down the road noticed that it was sounding great.

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    Bernard,

    funny... I posed the same question to Spectral a while ago, and I got smacked in the head - their response? "Capacitors have improved significantly since the Black Gates were spec'ed out"... and there you have it. More in the next post...
    Last edited by spectral; 10-03-2011 at 06:43 PM.

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    So there's been plenty of debate around the Mundorf Silver-In-Oil caps... To further qualify comments I made earlier, I picked up the following from one of the web sites I cited:

    # Mundorf MCap Supreme
    Metalized Polypropylene Film
    10uF/800VDC = $60.00

    All of the MCap Supremes are actually two higher value capacitors wired in series and placed inside a single wrapper. We found the original MCap Supreme to be the best reasonably priced capacitor available for loudspeaker cross-overs, today. It is rich, detailed, and full-bodied, though a bit softer sounding than the Duelund VSF. Relatively free of glare. Available in values up to 22uF.

    # Mundorf MCap Supreme Silver & Oil
    Metalized Polypropylene Film with Silver Flashing
    10uF/1200VDC = $148.00

    This is an oil impregnated, metalized paper capacitor, with the same series configuration as the original MCap Supreme. High-purity silver is used for the capacitor coating, and the winding is impregnated with a special oil. Despite the hype, we found the sound to be similar to the regular MCap, above. The major difference is that the sound spectrum shifted upwards, adding emphasis to the highs, at the apparent expense of the bass. While this creates a greater sense of air and transparency, the impression of a diminished bass response may not make it the best choice for a full-range speaker system.
    From my perspective, I'll just talk dollars and sense - the 10uF/800V Supreme is $57.37 while the 10uF/800V SIO costs $207.32 at partsconnexion as of this writing. Now, I am not going to spend $400 on two caps just to be... ahem... on the "safe side", w/o any indication how safe that side is... Perhaps I am wrong...

    For further reading, there is this thread on audiogon that many of us have perhaps already seen...

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    Super User Bernard's Avatar
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    I just noticed that Parts Connexion has a sale of 25% off "Alexander by Duelund" caps.

    Interesting info about Black Gate.

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    Spectral,
    for the panels - I have great experience with Obbligatos. Relatively cheap and small compared to competition.
    It requires some nerves to wait for delivery from Hong Kong but otherwise I can only recommend them.

    http://stores.ebay.com/diy-hifi-supply50
    ML Ascent (bi-amped, modded crossovers), Vacuum State (VSE) SVP-1, VSE modded Dynavox VR-80 monoblocs (panels), McIntosh MA-6500 (bass, modded), VSE Level 6 modded Sony SCD-555ES with internal UeberClock, VSE TMS-1 music server, modded Thorens TD 126 MkIII/WTA clone/Ortofon Vero, VSE silver interconnects, Monitor (inakustik) LS-1202, self-built power cabling and filtering

  14. #14

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    Quote Originally Posted by spectral View Post
    bernard,

    funny... I posed the same question to spectral a while ago, and i got smacked in the head - their response? "capacitors have improved significantly since the black gates were spec'ed out"... And there you have it. More in the next post...
    i don't care how much electrolytic capacitors have improved over the years, black gates are still the king - still a significant improvement over any other electrolytic available today, and i mean any. However film capacitors are another kettle of fish where black gates cannot match up to. For example mundorf silver/oil is definitely more transparent than any black gate model available. The only problem is that there are thousands of fake BG's flooding the market.
    Last edited by Dan Osib; 10-04-2011 at 10:51 AM.

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    I have edited post #8 above with the values of the 47uF and 51uF I have ordered; here they are again:

    47uF panel -> 2x 22uF + 3x 1uF Mundorf M-Cap Supreme
    51uF panel -> 5x 10uF + 1uF Mundorf M-Cap Supreme

    The 1uF's were preferred as to be as far way as the others. Finally, I have ordered a bunch of the Vishay-Roederstein 1839's as bypass capacitors.

    I am sure people are itching to hear the cost - about $1900, within the $2000 budget I set off with. Silver-in-oil-based combinations would have easily pushed the cost up to $8000 not counting the woofer caps.
    Last edited by spectral; 10-06-2011 at 06:50 AM.

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