My Take on X-BOSOZ

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#1,361
Once I figured out what would fit all I had to make the panel the power supplies are bolted to. Cases take longer than the rest of the project, I probably spent at least 8 hrs with all the drilling and machining. This one I purchased from John Ango at Antec, He is very good to deal with. Another shot
 

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#1,362
wirewiggler said:
Once I figured out what would fit all I had to make the panel the power supplies are bolted to. Cases take longer than the rest of the project, I probably spent at least 8 hrs with all the drilling and machining. This one I purchased from John Ango at Antec, He is very good to deal with. Another shot
Click to expand...


Yes i have to agree with you and John Ango, he sells great stuff and has great support for all his product. I have one of his chassis just like yours but bigger that i don't use, i think i should sell it.


Jase
 
#1,364
wirewiggler said:
Once I figured out what would fit all I had to make the panel the power supplies are bolted to. Cases take longer than the rest of the project, I probably spent at least 8 hrs with all the drilling and machining. This one I purchased from John Ango at Antec, He is very good to deal with. Another shot
Click to expand...


ugly!

:clown:

even if is service man's nightmare!
 
#1,367
Hi guys, I am new at this. Just starting to build the x-bosoz. Completed the PS board using this schematic:

http://www.diyaudio.com/forums/attachment.php?s=&postid=768273&stamp=1132178787

The -ve rail is fine, but having a problem on the +ve rail side. My zener string which is 63V starts turning black and smokes after about 1 min of powering on. I measure the V across the zener string and it is about 74V and the output is also about 74V. The power supply after rectification is about 83V

Appreciate any help or ideas on how to troubleshoot this issue. I have checked the layout and all is fine.

Thanx.
 
#1,369
Thanx for your reply. I believe you are referring to R4? I had checked it and it was ok. Anyway, the problem was my transformer. Now the PSU is outputting +62V and -11V.

Another problem. The output of both my pre-amp boards are very low. With an input of 300mV, I am only getting about 10mV of output. There is sound, but output very low.

Anyone has tips on how to check the pre-circuit and what to look out for?

Any help will be appreciated. Cheers!
 
#1,372
Antonytls said:
How much output swing could we expect from this preamp ?

It's to drive directly grids of au EL509 power amplifier.
Click to expand...
I Think the std version (BOSOZ) is about 25V S.E. or 50V P-P. Double that for DIff output. That would be for 60V supplies. Distortion climbs with output level!... This version would be somewhat less depending on your cascode voltage 😀

I have +80V on mine! Lots of headroom 😀
 
#1,374
Antonytls said:
Grid of my EL 509 PP will be bias between -40V and -60V.

Double push-pull - PSU=300V - Output transformer=1900 ohms

I think I will try it to for split stage and driver.
Click to expand...

in that case - you'll not have full swing from poor mosfet preamp , needed to awake those hungry grids; at least not needed swing for full blast

if you don't need full power , than it's OK .

but- you can try to make X-BOSOZ with bigger PSU voltages , and have what you need
 
#1,376
X-BOSOZ hummmmm

Russ,
Or anyone, lately I have noticed a hum from my X-BOSOZ / Joshua combo humming when volume is low, at full volume it goes away. I know it is a grounding issue. How did you wire yours? My ground on the X-BOSOZ board is tied to chassis ground threw a cl60 thermistor. The rest are isolated. I also have a hum when outputting to single ended devices (headphone amp tube amp).

Bill
 
#1,377
I have not had any hum.

First, my JT is on the X-BoSoZ outputs.

My mains earth is tied to the chassis, but is not connected to the signal ground at all.

If you want to keep the earth ground tie, you could try the back-to-back diode trick, which will require a couple volts of difference in ground potential before any current flows.

Try lifting the ground link to see if it eliminates your hum. Then you can plan your solution.
 
#1,380
G'day,
Over this past weekend I did the Zen Mod on my twisted xbosoz 'Jfet cascoded CCS-ed BOSOZ for Steenoe' mod, to my ears the difference in sound is huge, won't bore you with all the audio geek speak stuff but the mod is the dogs. So Zen Mod & Steenoe thanks will have to iron in the BC546 next when will this all end, well until I finish welding up the F4 hopefully this week.

Cheers
Bruce
 
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