x-bosoz

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#101
Re: 2-stage X-BOSOZ ?

CheffDeGaar said:
Hi there, X-Gurus

I already have a nice BOSOZ that drives my AlephX, and I was just wondering if I could go a little bit further...
So I'm wanting to "X" my Bosoz, and Henrik's work looks promising to me, but I have a question : my bosoz is a 2-stage one, namely two "native" bosoz cascaded. The first stage provides gain, and the other acts as a buffer (gain #1). The reason is that I wanted to keep the input and ouput impedances cosntant, wathever the volume setting...

So I was wondering how to "X" such a beast. Do I "X" each stage separately (local), or do I include all the mosfets in the "X feedback"? Which is one would sound the best ?

Here is the second solution, at least the way I plan it. Does it seem OK to you ?
(Yes, I know, a lot of stuff's missing, but you get the idea 😉 )
Click to expand...


this one looks very similar to the susy patend
 
#103
superstition said:
CheffDeGaar,

why don't you just use an input buffer instead of an additional bosoz? If i remember correctly there is an example somewhere in this or in the x-soz thread although it's purpose was to get around the low input impedance.

superstition
Click to expand...

Hi Supersition,

1) Gain stage before the buffer avoids amplifying the noise of the input buffer, at least IMHO... May be wrong :cannotbe:

2) What's the problem using two BoSoZ 😕 ? Needs only 2 more active devices (4 including the CCS), inherently balanced, supports heavy bias (yes I :hbeat: the sound of heavily biased MosFets)

3) That's my current (pun time) configuration, but not Xed, so only minor changes for major sound... 😉
 
#104
Looking at the patent and my own recent experiements, I think you will find the whole implementation a lot more simple than you might realize.

Assuming your terminology was misquoted, the differential input stage is obviously cascoded in the normal fashion and drives the gates of the mosfets, presumably in common source mode for currnent and voltage gain.

The realisation in working form can be taken from adaptation of the now popukar X Aleph .

Ian😉
 
#105
macka said:
Looking at the patent and my own recent experiements, I think you will find the whole implementation a lot more simple than you might realize.

Assuming your terminology was misquoted, the differential input stage is obviously cascoded in the normal fashion and drives the gates of the mosfets, presumably in common source mode for currnent and voltage gain.

The realisation in working form can be taken from adaptation of the now popukar X Aleph .

Ian😉
Click to expand...

Well, I must be dumb, but I'm afraid don't get it 😕

There's no cascode here, just cascaded stages. And I do not see how it could be more simple... All I just wanted is something surrounding the volume pot to keep both input and output impedances somewhat constant :bawling: Of course, there's the solution of the "classical" JFet buffer (http://www.diyaudio.com/forums/showthread.php?s=&threadid=19173, posts from Hans B), but why not use BoSoZ as a buffer ? (in fact I already use it, not Xed)... Where's my error ? Could you elaborate ?
 
#106
a little more experiment

Please note the capacitor c1 is added.
 

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#115
Hi David!

Nothing has ben remooved or altered from the original board - it´s that easy!
On the other hand, you could mount the parts at the backside of the board to acheeve even shorter wiring, but that isn't essential. I myself hasn't done this mod, I do everything point to point wirering on veroboards.

Regards Henrik.
 

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#118
Henrik said:
Algar_emi, you asked me for more specefic deatail on my x-bosoz - by e-mail, I thought I would answer your question on the forum, so here it is.

The rating of the torodials is as I remember, not far from the scematic.
The powersupply is inspired by Andrea Ciuffolis powersupply on his Powerfollower 99, an idea from Technics called "virtual battery" and has some similarities with ESP´s Cap. multiplyer. It works pretty good, very silent, and remooves most turn on thumb if there is any. Because of this I omitted the original 22 Ohm filtering resistor before the last PS caps.

Regards
Click to expand...

Hi Henrik,please i need to know if R122 and R123 (39K) is critical or i can use for example 47k value.
I need also to know what is the gain formula in to your modd. x-bosoz with R115 from 0 to 500 value.
Thanks in advance and best regards.

Antonio
 
#120
wuffwaff said:
Hi,
you can use 47k. Gain will be a bit higher and upper frequency limit a bit lower but not critical.

Original gain was around 10dB


William
Click to expand...
Hi William and thanks for your reply!
I still need to know what is the gain formula in to x-bosoz with R115 from 0 to 500 value and how much is critical the high frequency limit?
60khz 50khz or ?
Is it possible to know exactly?
Thanks in advance and best regards.
 
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