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    Speaker upgrades

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    corndog71

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    Speaker upgrades

    Post by corndog71 on Fri Feb 21, 2014 4:00 pm

    I kinda hijacked digdug's thread so I thought I'd start a new one to respond to Skizo's comment.

    sKiZo wrote:
    Corndog >> I see your point on the crossovers, but at $1800 each, I'd expect the Paradigm's to be a bit above that sort of encheapening ... then again, hard to tell without looking inside.

    PS ... here's the 4way crossovers in my McIntosh XR16's ... they look all right to me ... from what I understand, each coil is custom wrapped for that particular box ... not sure how I'd improve on that, but I'm open to suggestions.


    It's a bit of a mess.  I see a few electrolytics.  These are not good in speaker crossovers for a couple of reasons.  They're typically 20% tolerance to begin with so you lose accuracy there.  After about 10 years the electrolytic starts to dry out which increases resistance and throws the specs even further off.  A good polypropylene film cap (Erse Pulse X are 3% tolerance and still cheap!) will keep things in spec and resistances low for a long time.  

    Another area they dropped the ball at is arrangement of the inductors.  It may just be because these are older but nowadays the better speaker designers pay close attention to inductor layout due to magnetic field interaction.  

    If they have to be closer than say 6" then they should be mounted perpendicular to each other as I showed earlier.  As shown in your picture they will have a measurable effect and both will be thrown off value.  Granted, it may not be a lot but it's this sort of attention to detail that separates a good speaker from a great speaker.



    Another thing is the use of iron core inductors.  In a low pass circuit they're acceptable as an equivalent air core choke would get pretty expensive (although still superior).  They might also be needed for a specific DC resistance.  They have no business being in a midrange or tweeter circuit.  They can saturate and add distortion to the sound.  Air core inductors are the way to go.  

    Here's a crossover by Thiel for example.  I still see electrolytic caps but only a couple and they're likely not in the signal path.  No iron core inductors.  Nice, clean layout.


    Oh and as far as those Paradigm speakers go; they do some things right but still take short cuts.  Don't let the price fool you.  Remember that's the price of the speakers plus profit, plus dealer margin, plus packaging, etc.  The crossovers are almost always the place that gets compromised because they're hidden.

    So, if you're up for the challenge, I would recommend getting the schematic for your speakers if possible and getting to work.  Smile

    corndog71

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    Re: Speaker upgrades

    Post by corndog71 on Fri Feb 21, 2014 4:09 pm

    Here's an example of a good 3-way crossover.  There are still compromises but the areas that matter most get the goods.



    And again with my upgrades.



    And again using foil inductors for the midrange and tweeters. The iron core is such a big one that an equivalent air core is over $50 by itself!


    sKiZo

    Posts : 1313
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    Location : Michigan USA

    Re: Speaker upgrades

    Post by sKiZo on Sat Feb 22, 2014 3:28 am

    Good info ...

    There were a bunch of gurus redesigning the crossovers for a lot of the reasons you mentioned on one of the other forums, but no definitive results that I could come away with. Some numbers posted showing "improvements", but also some concerns about sonics that didn't match the original configuration. A good bit of argument and virtual eye pokes. Mine just sound so dang good I decided to leave well enough alone.

    The poly films were on my original want list ... I should probably at least follow up with that. I imagine it'd take some break in time for those to start to sing, and worse comes to worse, I could always swap back at a later date if I wasn't happy with the results.

    That'd also give me an excuse to reseal the boards to the boxes. The speakers aren't ported and have a tendency to develop air leaks at the connector panels - which are behind the crossovers. The woofs and lower mids were recently rebuilt, and I've had the speakers for 30 years now, so it wouldn't be out of order to put some work into the electronics.

    Thanx for the excuse to dust off my scanner ...  tongue 





    PS ... I also see what you mean about compromises. I checked a 5mH air core ...

    http://www.parts-express.com/jantzen-50mh-20-awg-air-core-inductor--255-060

    ... and we're talking a couple inches diameter and almost half a pound each! Then again, the XR16 is just shy of a 100 pounds, and it's not like there wouldn't be enough room inside ... it would take some serious structural engineering to make that work on the original boards though.

    corndog71

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    Re: Speaker upgrades

    Post by corndog71 on Sat Feb 22, 2014 11:09 pm

    Whoa!  Shocked 

    That is the craziest looking crossover I've ever seen!

    Well, if you think it sounds great then maybe just leave it alone.

    It looks like they have poly caps in all of the right places except C2. From the pic it looks like an electrolytic which doesn't suprise me as it's a big cap. If I were going to swap anything out it would be that one as well as C3 and C5.

    http://www.erseaudio.com/Products/PulseX250v/MPX25-03-20-00

    http://www.erseaudio.com/Products/NonPolarElectrolyticAll/ANP10C-05-50-0-PB

    75uF is apparently not a common value. You could parallel 3x 25uf

    http://www.erseaudio.com/Specials/ANP10C-05-25-0-PB-BLUE

    Have you heard any new speakers lately?  Cool 

    sKiZo

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    Re: Speaker upgrades

    Post by sKiZo on Sun Feb 23, 2014 12:36 am

    May seem overly complicated - a lot of that is the protection circuitry. Apparently you can't really hurt the speakers, and lord knows I've tried!  clown 

    I try to keep in touch with new. I was listening to a pair of Focal towers at the audio shop just last week. Those get very high ratings apparently. Call me set in my ways, but I feel they sounded too ... technical. Also tried on a set of Bower & Wilkins that had a real nice feel to them, and gave a listen to a set of the classic McIntosh ML1's fresh back from the same rebuilder I use ... very nice, but I'll stick with what I got.

    Mostly just sat around and shot the sh!t with a bunch of other audio junkies in from the cold.

    I bought the XR16's back in 1980 and never really felt the need to replace them. First project out of the McIntosh team that used their shiny new anechoic chamber. And yes - there was a lot of head scratching amongst the experts, but I knew they were what I wanted first time I heard them. I'm sure even Roger Russell raised an eyebrow at the design, but they've definitely stood the test of time here. One BIG advantage is the isoplanar design, which works real well with my Carver holographic setup. Also, they're just sweet all the way up the registers, and the bottom will flat out kick you around some and shatter your sternum if you let them. I recently did sweep tests and was getting usable SPLs down to around 22hz and could still sense them to just over 16hz ... don't need no steenking sub!

    Thanx and a tip o'the hat for the research on the caps - I'll do me some shopping and check back with you on the results.

    PS ... found the 75 µF ...

    http://www.erseaudio.com/Products/PulseX250v/MPX25-03-75-00

    Also found 51 µF in the same line. Rated +/- 3%, so they should be close enough to replace the 50 µF in C3?

    http://www.erseaudio.com/Products/PulseX250v/MPX25-03-51-00

    pigface

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    Re: Speaker upgrades

    Post by pigface on Tue Feb 25, 2014 9:09 pm

    Sorry about hijacking your thread . Very Happy
    but I want to say a big Thanks for this thread , because it gave me the incentive to take a look at the crossover  I took out of one of my Infinity Kappas  about six years ago because of a dead mid bass driver . I replaced it with a used one from ebay a while ago  and it has been in my closet ever since .
    After looking at it the last couple nights it turns out  it might be just a bad 5 ohm pot on that driver circut , it was reading open .  Since it seems a quality pot I was able to take it out and apart clean it and re-tension the wiper and contacts  and put it back in and it is now working . The complete  circut for the mid bass was open before  now I have some resistance in it .  All  left to do is hook it to an amp and hook a speaker to it and see if all the sections work ! I would like to put this back in because the used one I got was a little different in componentry , but it worked .

     Hopefully that is all that's wrong because most of the components are on the other side of the  circut board .

    it was the big one on the right side with the wires with the yellow markers on it

    corndog71

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    Re: Speaker upgrades

    Post by corndog71 on Wed Feb 26, 2014 12:03 am

    Great catch!

    It took me a long time before I had the guts to open up my speakers. For the longest time I assumed the crossovers were something that were not to be messed with. I never really gave them a second thought until I started following Danny Richie of GR Research. I've learned a lot about speakers from him and he's all about DIY.

    I encourage everyone to check out their crossovers. But beware, madness may follow.  Wink 

    pigface

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    Re: Speaker upgrades

    Post by pigface on Wed Feb 26, 2014 8:24 pm

    Thats one thing , I've never been afraid to take something apart to see how it works , Though Im not saying I've always been able to get it back together working . Shocked    But I do have to admit I have a good win to fail ratio .

    But this is a win .    I pluged a speaker in to all the  crossover  outputs and every one works !!  Now to solder it back in .

     Next  I might even eventually try my hand  to build my own  crossovers  for some old Boston Acustic  drivers I have laying around . If I can find the specs on them I'll build  a couple enclosures .

    pigface

    Posts : 72
    Join date : 2011-04-10
    Location : pittsburgh

    Re: Speaker upgrades

    Post by pigface on Sun Mar 09, 2014 1:22 am

    A quick update on my crossover repair , I finally got around to reinstalling it  and the pot repair fixed my mid bass problem . All is fine  again . Thanks again !

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