Converting a Fisher X-10 to Bozak B-401 Rhapsody

Discussion in 'Speakers' started by sruddy, May 17, 2017.

  1. sruddy

    sruddy Well-Known Member

    Messages:
    900
    I have rebuilt my Fisher X10s including new tweeters and just don't like the sound. Then I discovered Bozak by accident, as there were a set in a console I purchased. The console has the following.
    • B-199 Woofers
    • B-200Y Tweeters
    When I re installed the rebuilt Fisher 500c in the console and took a listen, I was immediately drawn to the large 3D sound stage! I want more! So I just purchased a set of B-209Bc from an Audiokarma member and am going to convert he Fisher X10 into a Bozak B-401 Rhapsody configuration. I'm going to need some help from the Bozak experts!

    First I need to figure if I can replace the front baffle or if I need to glue another baffle over top of the original. I plan on trying to remove it tonight. Then I still need the crossovers and can't find a thread with a schematic, parts list, and finished photo. There also seems to be a Tobin mod of two types a 101 and a 104 not sure which one to build. Also I'm wondering if I should use the Fishers midrange and treble controls.

    Here are a few photos.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     

     

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  2. drbiggles

    drbiggles I like bacon Subscriber

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    Hey man,

    Those X10's will be close to the Bozak B302A's. But same driver compliment as the Rhapsodys, either or. You may or may not be able to use the Fisher's controls. You're looking for the Pat Tobin 104T schematic. It's on the net somewhere, or download it from the Files section on the FB group. For such a needful crossover build for Bozaks, you'd think it'd be far easier to find.

    Open up the back of the Fishers and lets see what's going on with the front baffle.

    Biggles
     
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  3. Drugolf

    Drugolf AK Subscriber Subscriber

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    So to clarify, you want to basically replace the Fisher drivers with the Bozak drivers in the XP-10 cabinet and may need to replace or change the baffle?
     
  4. GordonW

    GordonW Speakerfixer Subscriber

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    Conversation message sent, regarding N10102/Tobin mod crossovers...

    Regards,
    Gordon.
     
  5. sruddy

    sruddy Well-Known Member

    Messages:
    900
    I found these, first one is in the Bozak Facebook files section.

    [​IMG]

    [​IMG]

    [​IMG]

    The front baffle came right out. I assume I should remove the grill cloth and start with a new board?

    [​IMG]


    Yep and build the crossover.

    Thanks for the offer. Unless I can find some cheap N10102s, and they have the same inductor values I need for the Tobin 104T Mod, I'll go the DYI route.

    This is a Parts Plus parts list I found.
    [​IMG]
     
  6. drbiggles

    drbiggles I like bacon Subscriber

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    Hey man,

    Yup, remove the staples and set the cloth aside. Measure the board and get new stock, cut to size. Do not mount the tweeters in the array over the B199 woofer. Mount them up higher on the baffle. We can get closer to exact placement later.

    I believe if you check Parts Express, you can now find the 1.1mH inductor in 18 gauge. Go for that one. Opt for the 5% Daytons if that's the manufacturer you're going to go with. I've tested the 1% and at nearly twice the price, you're not getting your moneys worth.

    Closer!

    Biggles
     

     

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  7. sruddy

    sruddy Well-Known Member

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    My front baffles measure 27.25 x 21.5 x .75. The tweeters are currently mounted separate from the woofer and don't have the angle I see in the original Bozak enclosures. Also I'm thinking of using the Fisher tweeter adjustment or replacing it with a new L-Pad. If I buy a new L-Pad which one should I get? The Fisher measures 1.5 - 25 ohm. I ordered the 1.1 inductors. Thanks!
    BTW what do you think of the non polar electrolytics vs the polypropylenes?
     
  8. drbiggles

    drbiggles I like bacon Subscriber

    Messages:
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    Location:
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    Hey mang,

    Modern electrolytics are miles ahead of 40+ year old versions. Even so, their value can be off. Testing the values of new electrolytics is key to making sure your crossovers are matched. They also have a higher ESR than their poly counterparts. This means they'll make the tweeters sound a little darker, they won't have quite the sparkle/air. Some prefer the rolled off highs and go this route. The choice is completely up to you. I've built maybe a dozen pairs of 104T crossovers and prefer Dayton 5% rigs. I realize that sounds kinda dull. The prevailing winds want something magical, something where they can say with authority that they've found the ultimate and Dayton's suck. It feels good to spend the big money for the golden choice. They way I see it, if I spend double or more on capacitors, I want my speakers to sound that much better. The chances of that happening are pretty slim. I make the previous comment based upon building or replacing caps on vintage loudspeakers, not new ones with fancy modern drivers.

    The fisher l-pads won't work for this project. You want an 8ohm 15 watt l-pad for the Bozak tweeters. Get the ones that have the 1" long shafts. They cheap, no big deal.

    That's nice and thick baffles there pally boy, good deal. The tough part is finding 3/4" replacements. Our sizes today are all over the damned place. Do the best you can and engineer your way out of it. Or, they may have what you need.

    I'm really, really jealous of this project. The style is going to match performance.

    Biggles
     
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  9. sruddy

    sruddy Well-Known Member

    Messages:
    900
    Right on, thanks man, I'll keep you posted.

    Steve
     
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  10. Retrovert

    Retrovert AK Subscriber Subscriber

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    Location:
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    Many do not like the attenuation of the Tobin modification finding it to be excessive at lower volume levels.

    This is why a continuously variable attenuator is generally preferable to Tobin's fixed value. One size does not always fit all.

    The attenuator value further varies with the input genre and how accurately the original recordings reproduced the high end/ So even when the level is tuned to your ear for one recording it may not be correct for another. I've elsewhere written on AK in detail about this subject.

    Biggles and I can give you an earful on reduction in the high end from the attenuator, but his suggestion of an L-Pad is what is recommended.
     
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  11. sruddy

    sruddy Well-Known Member

    Messages:
    900
    Apparently the AK member who I purchased the B-209B drivers sold me 16ohm speakers so if
    anyone can help me find an 8 ohm pair please let me know.

    Thanks
     

     

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  12. Retrovert

    Retrovert AK Subscriber Subscriber

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    Any of the B, Bc, or C versions will work. The B and Bc are rear mount and the C is front/rear mount. The Bc and C are ceramic magnets and the B is alnico. No difference in sound.

    As far as I know, the 16 Ω version was, and consequently remains, of very limited utility, appearing in a dual 8Ω woofer configuration, such as was used by the B-305 or the Symphony. It was used for systems predating the 16 Ω voice coils which, in parallel, yield 8 Ω. These may also appear in some of the fill-in line arrays used in large spaces.

    All, however, is not lost! You may use two of those drivers in parallel to create an 8 Ω center-channel speaker. I suggest an MTM configuration with the midranges slightly angled for better dispersion.
     
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  13. Retrovert

    Retrovert AK Subscriber Subscriber

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    Biggles is correct: avoid NPEs. Poly film capacitors are wonderful and inexpensive.

    Electrolytics have poor audio properties. These include, but are not limited to, limited lifespan; high distortion (acts like a diode in each direction); very high ESR, and high dielectric soakage which causes distortion. The only time NPEs appear in a signal path nowadays is for: (a) low cost, high sales-volume speakers designed to be short-lifespan or disposable, or (b) specialty notch filters with high values that could not otherwise be easily obtained, where the capacitor is essentially not in the signal path.
     
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  14. sruddy

    sruddy Well-Known Member

    Messages:
    900
    Thanks for the info Retrovert. I put the 16 ohmers up for sale in barter town. I have no use for a center channel speaker. Currently hunting for the B Bc or C versions of the midrange.
     
  15. drbiggles

    drbiggles I like bacon Subscriber

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    No luck in finding B209's for you at the meet on Sunday, or in my haul yesterday. Still looking.

    Biggles
     
  16. sruddy

    sruddy Well-Known Member

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    900
    Thanks for looking and the update. script56 said he had a pair. I'm waiting on the reply. I'll keep you posted.
     
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  17. sruddy

    sruddy Well-Known Member

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    Here are a few questions for you all.

    1. Should I put the drivers in the same place as the Rhapsody? The X10s front baffle is 27.25" x 21.5"
    2. How the heck can I make beveled cut outs like the Rhapsody has and does anyone have the angle and whole sizes?
    3. The tweeters are also angled how can I fabricate the tweeter holder angle piece?
    4. Can someone give me some measurements for the driver placement?
    Thanks!

    Steve
     
  18. drbiggles

    drbiggles I like bacon Subscriber

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    Hey Steve,

    Here's what I know from working with Bozak DIY projects. Rudy used a first order crossover, one of the benefits is that your drivers will image well without Nasa engineering to get them placed correctly. Keep the woofer centered and closer to the floor, this will help with bass response. Mount the midrange centered and above the woofer. You want enough room between the woofer and midrange so you can mount the midrange cover over the back. I've worked with a space of approximately 1/4", but that's too tight. Maybe 1/2" or so room between the rear of the drivers would be fine, up to 1". You can copy the layout of the Rhapsody, or simply mount the tweeters inline with the mid and woofer.

    I haven't had an opportunity to mount the original b200Y tweeters in pairs on the front baffle yet. So, I'm not much help here. I would suggest leaving the brackets that hold the 2 tweeters together and at an angle. You want to mount them so that the tweeters can disperse sound without being hindered by the cutout. The Rhapsody has a gap between the baffle and the tweeters, the cabinet is NOT air-tight. If I can remember, I'll take some pictures of how it was done with the Rhapsody and post them here. Hooyah!

    Biggles
     
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  19. sruddy

    sruddy Well-Known Member

    Messages:
    900
    Who ever did the console build didn't bother to keep the tweeter brackets. They just removed them and mounted them flat (see photo above) I thought I had to seal the cabinet if not O should be able to come up with a way to angle mount them. Maybe someone can give us the angle.
     
  20. sruddy

    sruddy Well-Known Member

    Messages:
    900
    Have any opinion on the mounting the inductors? The X10s had three and they were all just glued down all the same way. I saw somewhere that it's recommended to turn one on it's side.
     

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