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

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

  1. drbiggles

    drbiggles I like bacon Subscriber

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    I'd be okay with your equipment sitting on cardboard boxes in my living room. I agree, just refinish the existing veneer. Or, clean and wipe on some danish oil/similar. They have a story to tell, a history. If you wanted new looking speakers, you'd go out and buy new speakers.

    Biggles
     

     

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  2. Treyphan

    Treyphan Member

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    Thanks! It’s been a labor of love putting the system all together, and going through it all to bring it to bring them all back to there original glory!

    Most definitely agree on the “History, and a story to tell”! Man, if this equiptment could talk!

    Think I’m gonna go the Danish Oil/Steel wool route first. That should really be all they need. If not, then I’ll think about stripping/re-finishing.

    Still plan on implementing one of the stated tweeter box ideas, just need the time.
     
  3. drbiggles

    drbiggles I like bacon Subscriber

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    What you should be doing is, as you go throughout your day, scan for possible cabinets that can be repurposed. Maybe something along the lines of some small speaker system that would allow you to rebuild the front baffle. You really don't need much.

    I've got an early 1950's 10 cubic foot Altec 606 cloned cabinet. It looks as though it'd been used on a stage for over 60 years. It's hammered. Sure, I could refinish it. But it'd lose its magic. Even with the gouges the size of the grand canyon, a little love and it comes together.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Biggles
     
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  4. Treyphan

    Treyphan Member

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    Update # idk:

    Did the “Bypass” capacitors this morning. I ended up using Dayton Film Bypass caps in 0.1uf and .01uf values. After reading that @Retrovert and @drbiggles recommended them over more expensive “boutique” caps.

    I’ve used the pricey caps before, but figured I’d stick with the experts on this one. Why waste $ if I don’t have too. That’s $ for more gear or music.

    Well, I knew this would improve the sound, how much was my question. Well I’m happy to say....it change the sound alright! The highs now seem much more “focused” and “airy”.just an overall “cleaner” presentation.

    While I guess it would be described as “subtle”, it was on the verge of being “obvious”...... In my system anyway.

    The system already sounded absolutely spectacular, and these improvements have just boosted an already killer set of speakers.

    I realize I’ll obtain even more, once the Bozak tweeters are replaced or supplemented with a super tweeter. I’m close on a deal for some HEIL AMT tweeters. Which is the route I’d like to go.

    Til then though, I’m just thrilled with these Bozaks! Basically the “perfect” speaker. IMHO. For my tastes, anyway. With the MC240s driving them in mono, it’s allowed for a stereo separation and soundstage that I just can’t beleive is coming from a 70 yr old speaker design. The whole frequency range is straight butter! Sweet, seeet, detailed butter!



    @drbiggles
    I like the idea of a bigger cabinet being used.

    I have a line on some B300’s, the cabs are beat. I considered buying them for the Drivers, and looking for some Of these wonderful Bozak mid drivers, and using/fabricating a big ole cabinet for em! Stay tuned....I’ve got the Bozak bug bad.


    Sold 4 sets of my “personal forever stash” speakers, sense these Bozaks came around. I just don’t see using them enough to warrant them sitting idle. These are speakers from Vandertseen, B&W, Paradigm, AR....good stuff. They just can’t do what these Bozaks do....and that’s OK. Someone else can enjoy them.


    I’ve got my Bozaks!
     
    Last edited: Jul 15, 2018
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  5. Retrovert

    Retrovert AK Subscriber Subscriber

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    One of the rules of Bozak Cult is Simple and Inexpensive Beats Fancy and Expensive.

    The difference between the Dayton PP film and PTFE (tradename Teflon) is so small that I can't see any reason to use the more expensive PTFE.

    Thank you for posting the feedback about your experience! So many doubters and haters, so few experimenters willing to try the inexpensive route. Because how could capacitors costing a few dollars match (at least within the limits of audibility) those costing fifty times as much? Except it does.

    The dipole alignment in the dielectric is frequency dependent, among other factors. So higher frequencies better benefit.

    Yeah, isn't that amazing? Buy your last speaker first, and make it a Bozak.

    The AMT is an interesting tweeter. Because it has a backwave, I suggest you also enclose that in a lined flowerpot, especially if you install it in the cabinet with the other drivers. That way you won't have the backwave bouncing around in the room or in the cabinet, and, if in the cabinet, have the rear of the tweeter subjected to modulation by the woofer. (The midrange already being enclosed, assuming you did the flowerpot modification?)

    Because of efficiency (db/W) differences between the AMT and other drivers you may need to use an L-pad to dial in the performance.

    Now that the HEIL patent has expired, Parts Express has Chinese clones of the AMT for very reasonable prices. I do not have direct experience with them, but the reviews are positive. The design is such a simple thing it is hard to imagine it would poorly function as long as basic quality standards were upheld.

    Please report your experiences with the HEIL. It's always good to have data on such things. And if you can A/B those with soft domes, so much the better.
     
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  6. Treyphan

    Treyphan Member

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    Firstly, the Bozak Cult sure seems to share my feelings on a number of things, so yeah....im SLAMMIN the Koolaid! lol

    No problem reporting back, I find all to often in threads like these. People get the info they are after, and are never heard from again. I just dont feel like that helps the community at all, a community we all come to when in need. So why not atleast take the time to report findings, and maybe even thank the very generous people, who have donated their time and ideas...for free....its the least I/we can do.


    Regarding "boutique" caps, Ive used them before, in fact more than Id like to admit. Because of the exact thinking you posted. However, about a year ago, I switched to using Dayton PP Film caps in speakers. Because of the research and tests i did. I came to the same conclusion. Ive had nothing but success in doing so. I feel the Daytons are more than adequate, and Im not missing anything.
    Now, this was my first time using "non boutique" bypass caps. Again....success. I stocked up on the Daytons. And those will be my go to now.


    Truer words have never been spoken!




    Firstly, Yes. I did enclose the mid, via "the flower pot" method. Used 1 in cotton batting inside and out, and Secured with flexible urethane caulk and a few screws. Turned out nice. And made a nice improvement. Again, more than I thought.

    Ill be mounting the Tweeters in a Box on top. Similar to DrBiggles route. Looking for some nice smaller cabs to use, before I just make my own. Those HEILs are Parts Express are very interesting. The trade I have lined up, would basically get me the AMT HEILS free. As the piece Im trading was a garbage pick, that I fixed. :) If I have to cough up the cash, Ill go parts express route.

    The efficieny differences are something that 'worried' me. I figured a L-Pad would be needed. Ill need to really do my homework, to make sure these are implemented correctly. In your opinion. Is the HEIL method Im thinking of sound like a good idea? Or alot of work for a return that could be accomplished easier?? lol Just feel like if/when its figured out...it would be a really cool, sweet sounding speaker.....hmm.

    At any rate. These speakers are making this morning so much sweeter! Well, gotta go for awhile now......hopefully get the cabs done this week. And post more complete phtos. I have a decent amount I took along the way. Id like to put together a little overview, and add to this thread. All people learn differently. While most of the info is in the thread already....ya never know. It might help someone out there in the interwebz one day!


    Til later Bozak Cult.
     
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  7. drbiggles

    drbiggles I like bacon Subscriber

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    Yup. Whether it be 10 minutes or 10 days, you turn around and find that you've completely lost interest in most others. I say most, because I still have and want to keep my Stephens Trusonic 80FR project, and would love to have again, an early pair of AR's. Both are spectacular in their own right. But yeah, the Vandersteens are gone, IMF TLS 80's are gone, and so many others.

    Keep your eyes peeled for a pair of Bozak Rhapsodys. They're the same compliment you have, but in a 2 cubic foot cabinet. I know, I know, it sounds too darned small. But they have their own flavor and they should be experienced/owned.

    Be careful about bringing home every stray Bozak you find. Make sure you have a good use/need for them as a whole, or the guts. They multiply just like any other audio treasure and you can find yourself swimming in very little time.

    Biggles
     
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  8. Retrovert

    Retrovert AK Subscriber Subscriber

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    Technically speaking, Jonestown was Flavor Aid.

    That is the right attitude to have. Contribute, don't just take.

    The Daytons are very good for the money. Glad you were able to save some cash and get the sound you wanted.

    Every speaker I've owned has not covered the midrange so there's been cross-modulation, and I've come to consider this as "normal" sound. When the cross-modulation is eliminated, it suddenly becomes apparent that one has been listening to distortion for a long, long time.

    I have had the same experience with crossovers using electrolytic capacitors and cored inductors. Something just isn't quite right. But there was no way to make the speaker at that price point without NPEs and cored inductors. This is why even Bozak switched. So much for efficient market theory.

    I suggest you ensure that your tweeter cabinets are time-aligned with the other drivers. Make sure that the acoustic centers of your tweeters are in a vertical plane with your midrange and woofer. That ensures the frequencies all arrive at the same time. Dahlquist did this, and you can read the favorable reviews for the technique with a search.

    No worries.

    The L-pad simply allows you to balance the tweeters. You can do the attenuation (1) as per the Tobin modification (variable rheostat) or (2) remove the Tobin attenuator and switch to a traditional L-pad configuration where the L-pad is used as an L-pad.

    As long as you can dial in the balance everything is fine. You'd need to do this with any tweeter, as some of them are more efficient than the B-200Y.

    I can't comment on the AMT or ribbon tweeters for this application because nobody, including me, has yet used them with Bozaks. I have suggested people try this, but the only tweeter experiments of which I know are those by Biggles. His SEAS soft-dome worked out better than expected. The Bozak cone tweeter is not as good as modern tweeters past about 8k Hz to 9k Hz. I know this is blasphemy, but tweeters did improve in the past fifty years.

    I have also suggested doing a four-way, where the B-200Y tweeter is cut at, say, 9k Hz using an inductor (build a band-pass just like for the midrange) and then switch to a modern tweeter to go from 9k Hz to 20k Hz. I also suggest putting an inductor on the higher tweeter to cut it at, say, 25k Hz, just in case the amplifier has ultrasonic noise or oscillation. That will protect it from damage.

    Glad you like your Bozaks.
     
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  9. Retrovert

    Retrovert AK Subscriber Subscriber

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    Bozaks tend to bring home friends: "I found this Concert Grand at the curb, mom, can I keep it?"

    Next thing you know, you have a problem and need to attend Bozak Anonymous. "My name is Joe Bob, and I have a Bozak problem. It has been ten days since I last dragged home a Bozak. But I couldn't resist, as it had the B-209C midrange which I can mount front or rear..."
     
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  10. drbiggles

    drbiggles I like bacon Subscriber

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    Bozak B-209C, the midrange that swings both ways.

    If it's free, then it doesn't count in your inventory. Dang, that'd be a great tag line.

    Biggles
     
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  11. Retrovert

    Retrovert AK Subscriber Subscriber

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    You ever attend one of those parties where everyone puts a midrange in a pile, and you get to take a random midrange home and try it out? Whoah. I'm told it's a big deal in suburbia.

    Yeah, that's the way to end up with one's basement on A&E's Hoarders next Tuesday.
     
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  12. drbiggles

    drbiggles I like bacon Subscriber

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    I was at a party years ago where about a dozen naked people were in the master bedroom doing unspeakable things. If it's like that, then I probably missed it. I have a thing about having the only exposed, erect midrange in a room.

    Biggles
     
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  13. Retrovert

    Retrovert AK Subscriber Subscriber

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    It's ok to cover your midrange with a flowerpot. Cotton batting helps, too. No shame in the midrange game.
     
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  14. Treyphan

    Treyphan Member

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    Hello hello Bozak Cult faithful!

    IM BACK!! Lol So I’d like to thank both @drbiggles and @Retrovert for helping me “see the light”. I already knew I was a huge Bozak speaker fan, and fan of ole Rudy himself. Man what I would give for to be able to buy that man lunch and pick his brain. As well as thank him.
    The Latw Mr. Pat Tobin as well. For all he and his people did for these speakers. Me. Bozak would’ve been proud I think.
    Ok, enough of the mushy man crush stuff. Lol

    Now for the reason I’m here...” Hi, I’m Treyphan, and I’m a Bozak-aholic. My “Tobinized” 302a’s are just splendid. The addition of the by-pass caps really helped, and Retroverts “l-pad, but not really and L-pad” is clutch. Or was the Biggles idea. Either way. Great job!
    I’ve sense picked up a pair of Mint Bozak B-401’s in the Boxes. More for the Crossovers and Drivers(yup the aluminum ones) than anything. Couldn’t pass em up for the price, less than a Benjamin. They’re in working order. And I’ll do something with them soon.

    However...the real reason I’m back is due to my latest Bozak SCORE! Some B-4000a Moderns aka Symphonies, in killer shape. Unfortunately, some stooge covered the gorgeous walnut with some ugly 90’s black Formica to match there Giant entertainment center. Fortunately, it’s peeling in most places, and the original Veneer lays untouched under it. It will take some work, peeling off the Formica, then stripping the glue and re-finishing. Fortunately, I’m quite the woodworker. Worst case I’ll re-veneer, ONLY if the original is not Salvageable, but it is. I’m confident in my abilities. Done more with less.

    Now my questions. These are setup for Bi-Amping, with the N-107 x-over. Which is nice. But I prefer to keep and active crossover out of the system. Unless I found one of the Bozak ones. Even then, I’m not sure no-amping with Mc240’s, or any tube amp for that matter is a good idea. Will a tube amp be ok not receiving the full “load”?
    Right not they are hooked up with a 240 strapped for each side. They sound great. All drivers are the aluminum ones, sell besides the woofer’s obviously.
    The Mid Covers are in great shape. Though I may do the flower pot mod as apparently that shape is more conducive than a half sphere?


    My question is this...I know the non bi-amp Symphonies came with the N-102a like my 302’s.
    Are there Tobin mods for the N-107? Looked like one cap on the “Low Leg” and a cap and an Inductor on the “high” leg?

    Would I be better off replacing with a N-102a like my B302a’s?

    If there is a mod for the bi-amp, I’m in. I just want to take these as far as possible.

    Any help is certainly appreciated. These Bozaks sure do have a way of following you home! That’s for sure.

    Got a Line on some Concert Grands, but I really don’t have the room, and these symphonies should get me most of the way.
     
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  15. drbiggles

    drbiggles I like bacon Subscriber

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    Hey Treyphan!

    Congratulations on all the Bozak scores! I'm running my Rhapsodys front and center at the moment, tough to move to the side for anything else.

    As far as bi-amping Bozaks, I don't know. It's not as simple as other systems. Rudy had his own way of doing it and I've not tried it. I ran my Symphonys with a standard Bozak 3-way crossover with the Pat Tobin changes. I use the same crossover for the 302's and the Rhapsodys.

    You're most certainly welcome for the help, it's what we do. I'm sorry I cannot be of any assistance with the bi-amping stuff.

    Biggles
     
  16. Treyphan

    Treyphan Member

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    No prob Biggles! I think that’s what I’m going to do, is run them with the Tobin Mods and Three way crossover, like my 302a’s.
    Right now, I’m just using a jumper and essentially running them “full range”.
    I’ll leave the N-107’s in there, just disconnected.
    So I could just find another N-102 x-over, like my B302s? Right? Then run wires the same way. I’m just curious that all those tweeters are still an 8 ohm load?
    The woofers are 16 ohm in series, so the amp will see 8 ohm.

    The bi-amp feature is nice. However I don’t have the special active Bozak crossover, and don’t really feel like putting another piece in the signal chain. I’ve read where the recommended crossover points are, and that other actives can be used. But that sounds like a headache. Lol

    If anyone has some original N-10102 x-overs they wanna get rid of, let me know. I’ve already got all the caps, and resistors to “Tobinize” them.

    Can’t wait!
     

     

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  17. Retrovert

    Retrovert AK Subscriber Subscriber

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    All one need do for bi-amping is is to split the signal much as a crossover would so that each amplifier receives only one half of the frequency range: woofer to one, midrange/tweeter to another. The special Bozak gear is not required.

    Consider how this works. Given the woofer and midrange are crossing at, say, 400 Hz, then one amplifier handles only the range 20 to 400 Hz, and one amplifier handles only the range 400 Hz to 20,000 Hz. Because the midrange and tweeter are sharing an amplifier, the crossover is still needed to split the signal between those drivers.

    Splitting the signal at the output of the preamplifier is an easy task. It could be done using an inductor (passes lows below a certain frequency) and a capacitor (passes highs above a certain frequency). But it can also be done using a gyrator (opamp or transistor) much as how an equalizer works. That is the approach Bozak took for the module which splits the signal into high and low. This approach while more expensive than the purely passive solution, eliminates the phase shifts which would otherwise be introduced and does not attenuate the signal.

    Beyond providing additional headroom, another advantage of bi-amping is, of course, eliminating any phase shift from the inductor as well as any power loss in the woofer caused by the DCR. The midrange/tweeter combination still requires a crossover, with the associated phase shifts, but then there's the tri-amping solution...
     
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  18. Treyphan

    Treyphan Member

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    @Retrovert thanks! I understand Bi-Amping. But wasn’t sure what exactly the Bozak N106 box was.
    I may try to recreate it.
    My question is this, right now I’ve just “tied” the low and hi inputs together with a jumper, similar to how most bi-amp’able speakers come. Incase you don’t bi-amp.
    I assume this is safe? As the passive crossover in the speaker is “splitting” up the signal.

    I thought it was odd the Bozak would offer an “external” crossover, to be used with the Passive internal crossovers. As usually no passive is used with active crossovers. However from your explanation....I gather that the external box is just splitting the frequencies, then the passive comes into play to split the mid/hi’s.

    So in my case right now, using one amp per speaker, with hi and low jumpered together is safe for my amp.

    I’d like to hear what Rudy had in mind with the biamped Symphony.
    However, I won’t have the Tobin mods that really took my 302’s to the next level.

    I assume there are no Tobin mods for this biamped setup?

    Guess I could pull my 302 crossovers and see what the Symphonies sound like that way.

    Leaving the Original Biamp Crossover in place, until I find a schematic or figure out a “copy” of Bozaks external box, you so eloquently explained.

    One last question. Would the Symphonies still be an 8 ohm load when the hi’s and low’s are tied together?
     
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  19. Retrovert

    Retrovert AK Subscriber Subscriber

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    You are shorting the N-106 (the active part of the splitter) outputs together? That is not a good idea as it can damage the device. I think what you mean is you are combining the input to the crossovers?

    What is common in speakers is to have the woofer and midrange/tweeter separated prior to the crossover network. So the crossover either has (1) a unified input, which it them separates, or (2) if the jumpers at the speaker terminals are removed, each crossover (woofer and midrange/tweeter) receives a separate input which is then additionally filtered.

    Correct. The box creates two separate signals in different bands. You've likely seen a similar approach with the subwoofer output for a surround system, where the output is low-voltage and low current, as it is intended to drive a powered subwoofer.

    The Tobin modification changes the crossover point and attenuates the tweeter. Those modifications are separate from bi-amping, in that bi-amping could use any crossover point or tweeter attenuation. Totally distinct issues.

    Can you elaborate on this question? It isn't clear to me what you are asking.

    If two drivers are placed in parallel without a crossover the impedance is halved. The crossover isolates the drivers (within rolloff limits) so the overlap does not occur for common frequencies, so the impedance is not altered.
     
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  20. Treyphan

    Treyphan Member

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    What I mean, is rather than using an amp for the “low” and “hi” inputs. I’ve run the speaker wire from a single amp to the “low” input, with another short set of wires “jumping” that input up to the “hi” inputs. Powering the speaker with one amp, not 2, for no-amping.
    Similar to how modern “bi-amped” speakers work. If you plan to bi-amp, you remove the “binding plates” that then allows for bi-amping, if you leave the binding plates(wire jumpers in my case) you can run the speaker as a full range with one amp.
    That’s how I have them hooked up, as I don’t have the N106 or other active crossover.
    Though I plan to buy the N106 if I can find one, or make my own.

    Basically, can the B4000a’s be run with only 1 amp??? Hope that’s clearer. Thanks again.

    What I mean, is with the sections “unified”, using only one amp with “jumpers”, is it still an 8 ohm load the amp sees?
     
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