My Take on X-BOSOZ

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#561
Hmmm... 20-25V drop across fet, 0.08A per fet ... 2W per fet if dual mono supply, 4W if a shared supply. Should be fine as long as the heatsinking is adequate. Use a sink rated at 5W to be on the safwe side, but otherwise should work fine.

Cheers, Terry
 
#562
~94vdc after rect ? ?
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Marc, I think you can go for that, but dont skimp on the heatsinks on the regs in that case! Your regs will have to dissipate a bit of heat. NP used 2x60V AC to get 2X60V DC for the BosoZ! So the original BosoZ has to throw off nearly the same voltage! Not too bad🙂
"Also, will a 6.2v zener work as D1 (instead of a 6.8v) as just mentioned by Russ/Brian? This I have no clue....
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I dont think the small diff. will be of concerne. As long as your trafo can supply the needed voltage for the zenerstring! I wouldnt go any lower though!

Steen😎

BTW I have to do major work on my house! So I guess I wont get to enjoy this forum for a while:xeye: The water tubes are broken, and I am diggin up the floor, god darn!! See you, guys!
 
#563
Re: Balanced volume control for Twisted XBOSOZ

Russ White said:
Ok Guys,

Between playing with my daughter's new toys and keeping my spouse happy I had a little time to design a small PCB for a balanced stereo volume control for Twisted XBOSOZ. It should work fine with anything from 5-20VAC power in the 20-30ma range. 🙂

The circuit is simplicy itself 2 Maxim DS1868 digitally controlled dual linear potentiometers which have a very good reputation and I have used them with success in the past (with a digitally controlled active filter) and a PIC12F675 to crontrol them. The rest are simply PS bits and interface.

The interface is a linear pot with center detent for balance, and a log pot for volume. The pots are read by the PIC's ADCs and the 8 bit results are used to calulate the channel volumes. There are no passive components in the signal path, just the two DS1868 which have very good SNR.

The board is small and simple, but it leaves the door open to experimentation.

Brian says we can do kits for these at a very reasonable price, and I am sure the PCBs will cost about the same as the Kookaburra.

Here is how it looks so far, remember this is still a work in progress. Any feedback is appreciated.

The PIC is on the bottom to use the copper pous to block some RF from the signal bearing devices. I have used this trick with success before.
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Hi,

Is there any news on this?

Is it possible to use the RelVol3 kit from Dantimax (as an alternative)
http://electronics.dantimax.dk/Kits/Selectors_-_attenuators/11021337032.html

Just noticed this can be sold as a 5k pot (any value actually)

Thanx, Ronald
 
#564
Re: Re: Balanced volume control for Twisted XBOSOZ

Duck-Twacy said:

Hi,

Is there any news on this?

Is it possible to use the RelVol3 kit from Dantimax (as an alternative)
http://electronics.dantimax.dk/Kits/Selectors_-_attenuators/11021337032.html

Just noticed this can be sold as a 5k pot (any value actually)

Thanx, Ronald
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That look's pretty nice. EXCEPT for the cheap rotorary Control. I have one now and i wish i didn't. But it is replaceable with a better one. I find with mine i have ti turn it so many times to get it to work properly.. OR SLOWLY turn it one click at a time. I guess it all comes down to what type of encoder it is..

J'
 
#565
Guy's this is what i am using. I love it.. digi01 made them. I think we should get something simular.

Balanced
LCD Display
Mute
 

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#566
Some Pictures

Here is my preamp fully assemble with a few caps omitted for a better view.

Notice how the Fets on the preamp are mounted to a 2" section of the "barred boss" aluminum heatsink. Works out very well.

The preamp and power supplies with 1/2" standoffs will easily fit into a 2.75" high case.

I am going to use a 16" x 12" x 2.75" case.

Cheers!
Russ
 

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#567
Re: Some Pictures

Russ White said:
Here is my preamp fully assemble with a few caps omitted for a better view.

Notice how the Fets on the preamp are mounted to a 2" section of the "barred boss" aluminum heatsink. Works out very well.

The preamp and power supplies with 1/2" standoffs will easily fit into a 2.75" high case.

I am going to use a 16" x 12" x 2.75" case.

Cheers!
Russ
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Russ good job 🙂

Are you guys able to get more of them heatsinks ?

Would be perfect for the group buy and have them screw holes drilled and tapped 🙂 I certanly would like a set 🙂

J'
 
#570
FET Spacing

Russ,

Measuring from the board it looks like the FET's are spaced about 39/64 or 0.61 inches apart. Could you confirm the spacing you laid them out at? I know it is easiest to mark the heat sink using the mounted parts, but that gets a bit awkward at times.

Thanks,

Craig
 
#573
I had a wonderful discussion a couple of months ago with John Michell when he was in town. I leave it to you to research the connection. There are always alternative views on a subject. Some traditionalists still like the old system.

Actually, I could not find my ruler with hundredths of an inch.
 
#575
jleaman said:
Russ what about my questions ?
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Sorry Jason, pretty busy watching playoff football today. 🙂


Brian and I are considering offering pre-drilled/tapped heatsinks, but we are looking at the cost/work factors. As it is it only takes an hour's work or so to get a couple HS ready to go. I actually cut mine from a single 4" HS. The drilling/tapping actually goes pretty fast.

Cheers!
Russ
 
#577
Transformers

I am negotiating with Avel for a custom trafo for our XBOSOZ. I was away pretty much all of last week on a very important business trip for me (real job) so I didn't get to follow up with Avel, but I am going to be in touch with them tomorrow and with a couple of other manufacturers as well. The plan is to get a custom 58V and 22V dual secondary 30VA toroidal trafo which should be an excellent match.

Cheers!
Russ
 
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