Bozak Crossover
- Thread starter elie774
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Listen to Sam's post below, he's done the mods, I haven't yet.
<This space originally contained the 101T crossover schema>
I'm eventually going to try this on a highly modified lowboy Concert Grand, as well as some other DIY Bozak-based efforts.
<This space originally contained the 101T crossover schema>
I'm eventually going to try this on a highly modified lowboy Concert Grand, as well as some other DIY Bozak-based efforts.
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That's the 101T. From what I've read in various places, Mr. Tobin started recommending that the B302 crossover be set to his 104T design several years ago, moving the B302's high 800Hz crossover to the 400Hz point used by the larger Bozak speakers. There is a thread at the Steve Hoffman forum detailing all of this. Rudy Bozak designed the B199 to go low, not to reach up very high, and 800Hz is pushing it.
What isn't mentioned in a lot of the threads is that the inductors have taps, and you have to make sure you're using them properly. After some digging, I found THAT information buried at the Bozak Yahoo group. I only went looking for it after re-installing my rebuilt-as-101T crossovers and noting that the bass was lacking a bit while the mids and highs were quite aggressive.
That said, I now have everything needed that a relatively electrically informed person needs to properly rebuild and upgrade the Bozak N-10102 crossover saved on my computer. If anyone needs it, send me a PM with your email, and I'll send it along.
Now to go crack open my B302s again and switch the inductor taps. I still need to order the 50uF caps to replace the 25s on the B209 section.
What isn't mentioned in a lot of the threads is that the inductors have taps, and you have to make sure you're using them properly. After some digging, I found THAT information buried at the Bozak Yahoo group. I only went looking for it after re-installing my rebuilt-as-101T crossovers and noting that the bass was lacking a bit while the mids and highs were quite aggressive.
That said, I now have everything needed that a relatively electrically informed person needs to properly rebuild and upgrade the Bozak N-10102 crossover saved on my computer. If anyone needs it, send me a PM with your email, and I'll send it along.
Now to go crack open my B302s again and switch the inductor taps. I still need to order the 50uF caps to replace the 25s on the B209 section.
These threads: http://www.audiokarma.org/forums/showthread.php?t=392854 http://www.audiokarma.org/forums/showthread.php?t=361932
The past few years, Mr. Tobin was advocating the 104T for all Bozak speakers over his older 101T design. The inductors are tapped, moving the taps gets you the different values shown.
The past few years, Mr. Tobin was advocating the 104T for all Bozak speakers over his older 101T design. The inductors are tapped, moving the taps gets you the different values shown.
I have made them, as you have found out Arran. I'm sorry, but I did not find any photos of the ones I made. Pat Tobin recommends the use of the 104t crossover as posted above by MRL_Audio. He recommends air core inductors, as the originals were and that the midrange be of 20 gauge wire and the woofer be of 18 gauge. Parts Express likely has these (that's where I got mine) as well as a variety of the poly caps with the values on the schematic. They also stock the resistors needed. I've got to hit the rack now, but I'll pull together a sample parts list tomorrow. I've got some old e-mails from Pat Tobin I can sift through as well.
I used 5% Dayton caps and Dayton audio-grade resistors from Parts Express. My original inductors were still good, so I left those alone, but PE's should be fine.
The 50uF caps are a bit spendy, but the sound of a properly-operating set of Bozaks is worth it.
The 50uF caps are a bit spendy, but the sound of a properly-operating set of Bozaks is worth it.
Scratch built parts list example for (2x) 104T Crossover
Quantity, type, value, Parts Express PN
2: Polypropylene Capacitor, 50uf, 027-443
2: Polypropylene Capacitor, 8.2uf, 027-426
2: Polypropylene Capacitor, 2.0uf, 027-414
2: Air Core Inductor, 20ga. 1.0mH (close enough confirmed by Mr. Tobin), 255-048
2: Air Core Inductor, 18ga. 3.0mH, 255-274
4: Resistor, 4.0 ohms, 004-4
2: Resistor, 7.5 ohms, 004-7.5
Assemble as shown in the schematic and you'll have your crossover(s)
Quantity, type, value, Parts Express PN
2: Polypropylene Capacitor, 50uf, 027-443
2: Polypropylene Capacitor, 8.2uf, 027-426
2: Polypropylene Capacitor, 2.0uf, 027-414
2: Air Core Inductor, 20ga. 1.0mH (close enough confirmed by Mr. Tobin), 255-048
2: Air Core Inductor, 18ga. 3.0mH, 255-274
4: Resistor, 4.0 ohms, 004-4
2: Resistor, 7.5 ohms, 004-7.5
Assemble as shown in the schematic and you'll have your crossover(s)
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Try 004-7.5
for the resistors. It should have been "004". I have edited and corrected in my previous post. Sorry about the oversight. Thanks JimHRB for catching my error.
OK, I've been messing with mine and have some questions.
For the 10102A crossover being modded.
Is the 104T the mod to use as opposed to the 101T??
Which taps are used for the inductors? I moved the B209 inductor (A?) to the 102 top tap location based on the picture I found here. Is that correct? Does one have to move the bigger inductor for the B199 too? I left mine at the lower N-101 tap
A 50 uf cap is used in the B209 leg, not the 25 uf???
Yes, I'm using electrolytics because they are here. If I like what I hear, I'll order some polys...
For the 10102A crossover being modded.
Is the 104T the mod to use as opposed to the 101T??
Which taps are used for the inductors? I moved the B209 inductor (A?) to the 102 top tap location based on the picture I found here. Is that correct? Does one have to move the bigger inductor for the B199 too? I left mine at the lower N-101 tap
A 50 uf cap is used in the B209 leg, not the 25 uf???
Yes, I'm using electrolytics because they are here. If I like what I hear, I'll order some polys...
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