Tried and true crossover upgrade: Tobin Mods for Bozak B302a
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jessdw
Active Member
I'm impressed that you managed to cram everything inside the old cap box. I just did away with it and used some terminal strips. Nice work! Also, I'm not sure if you're completely finished yet, but Pat Tobin also makes a good argument for moving the jumper from the smaller inductor from the N-101/N-104 terminal to the other one, marked N-102. Apparently the crossovers were designed in a way that basically caused the mid to play well into the range of the tweeters effectively doubling those frequencies. By moving the jumper it eliminates that doubling. Pat gives the full explanation here (about halfway down the page):
http://www.stevehoffman.tv/forums/archive/index.php/t-75950-p-2.html
http://www.stevehoffman.tv/forums/archive/index.php/t-75950-p-2.html
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tensleep, what happened to the crossover schematic that you had posted?
It is my belief that the portion of the circuit containing the 2.0 uF cap is an RC notch filter, the purpose of which is to tame a known spike in the driver. If I am correct, the purpose of the 2.0 cap would be to determine the center frequency of the notch. Changing from 2.0 to 2.2 uF would slightly lower the notch center frequency.
Please excuse my uncertainty. I have seen passive notch filters discussed in speaker design books, and have even used them successfully. But I have not seen a notch filter with the exact design as shown in your schematic.
It is my belief that the portion of the circuit containing the 2.0 uF cap is an RC notch filter, the purpose of which is to tame a known spike in the driver. If I am correct, the purpose of the 2.0 cap would be to determine the center frequency of the notch. Changing from 2.0 to 2.2 uF would slightly lower the notch center frequency.
Please excuse my uncertainty. I have seen passive notch filters discussed in speaker design books, and have even used them successfully. But I have not seen a notch filter with the exact design as shown in your schematic.
tensleep
Addicted Member
Thanks for the explanation. I am not sure why you can't see the schematic. I'll see if I can make a permanent attachment.
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tensleep
Addicted Member
I got busy last night, cleaning and oiling the Barzilay furniture while I had the speakers out in the shop. I also did the console, but still have to do the sliding doors tonight. Needless to say, I hit the chair for a couple of hours and then to bed. Here are some pictures, in no certain order:
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tensleep
Addicted Member
I am currently listening to Richard and Linda Thompson as the capacitors open up. The improvement in detail is already remarkable. The bass is much tighter and deeper/clearer. Yesterday, in the garage, I was running an Alesis RA100 for power, and was using an old Radio Shack mixer, in good shape, as a preamp. My source was an Archos 604 multimedia device, playing lossless .wav files. I had the playback on mix and Green Day, American Idiot came up and shocked the heck out of me - these Bozaks will really rock, now! Then, Ry Cooder came up, doing 5000 Country Tunes. The upright bass fiddle was exquisite.
Currently, I am running a Kenwood KM-X1000 for power, my Yamaha CR-1020 as a preamp and an Archos 104 multimedia player as my source, playing .wav lossless files. I had queued up The Black Keys, Brothers, on vinyl, something is amiss between my Kenwood KD-5066 and my Yamaha. They are both next on my to do list.
The Howard's Restore A Finish, followed by Howard's Feed 'n Wax, wasn't all the way dry last night, so, I'll polish it out tonight. This hobby is great!
Currently, I am running a Kenwood KM-X1000 for power, my Yamaha CR-1020 as a preamp and an Archos 104 multimedia player as my source, playing .wav lossless files. I had queued up The Black Keys, Brothers, on vinyl, something is amiss between my Kenwood KD-5066 and my Yamaha. They are both next on my to do list.
The Howard's Restore A Finish, followed by Howard's Feed 'n Wax, wasn't all the way dry last night, so, I'll polish it out tonight. This hobby is great!
