According to most responses the BosoZ outperforms the BoZ. According to Mr. Pass, this is due to the distorsion type (2. or 3. harmonic structure) and that most people perfers 3. harmonic to 2.
I will only need single ended in and out and I am therefore thinking about why the BosoZ should be better?
The main differences as I see it is that BoZ has a relative high Source resistor (100R), give some amount of local feedback. And that the bias is somewhat assymetrical (20V accross MOSFET and 40V accross Resistor), perhaps giving the sonic signature?
My purpose is to drive an F4 and to get a sound close to a vacuum tube preamp. Therefore I am leaning towards the BoZ circuit...but BosoZ is more flexible...
Why is Boz biased at 20V at output instead of half-supply (30V)? Would changing this alter performance towards BosoZ?
The major question is, is the sonic difference more a matter of personal taste (like tubes versus transistors) or is the a major step up in quality from BoZ to BosoZ?
I will only need single ended in and out and I am therefore thinking about why the BosoZ should be better?
The main differences as I see it is that BoZ has a relative high Source resistor (100R), give some amount of local feedback. And that the bias is somewhat assymetrical (20V accross MOSFET and 40V accross Resistor), perhaps giving the sonic signature?
My purpose is to drive an F4 and to get a sound close to a vacuum tube preamp. Therefore I am leaning towards the BoZ circuit...but BosoZ is more flexible...
Why is Boz biased at 20V at output instead of half-supply (30V)? Would changing this alter performance towards BosoZ?
The major question is, is the sonic difference more a matter of personal taste (like tubes versus transistors) or is the a major step up in quality from BoZ to BosoZ?
Check this out http://www.diyaudio.com/forums/pass-labs/146310-bf862-preamp.html
You will need to adjust the gain for F4
I am not sure if you can run the BOSOZ single ended in and single ended out.
If you can, I wonder if all the positive comments still apply.
You will need to adjust the gain for F4
I am not sure if you can run the BOSOZ single ended in and single ended out.
If you can, I wonder if all the positive comments still apply.
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Juma's BF862 pre isn't intended for driving buffer amp .
Juma can make preamp which will make your speakers bleed ........ but this one isn't of that sort
Skorpio - there is ( somewhere ) thread named BOSOZ for F4 or something like that
if I remember well - result is jfet based cascoded differential stage ........ that thread later results in funny
development
Juma can make preamp which will make your speakers bleed ........ but this one isn't of that sort
Skorpio - there is ( somewhere ) thread named BOSOZ for F4 or something like that
if I remember well - result is jfet based cascoded differential stage ........ that thread later results in funny
development
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Also check out this http://www.diyaudio.com/forums/pass-labs/156397-pearl-two.html
I am pretty sure the gain is easily adjustable.
EDIT: Thanks for the info Modstar
I am pretty sure the gain is easily adjustable.
EDIT: Thanks for the info Modstar
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last time I looked - Pearl was phono dedicated stage .....
I'm not telling that you can't make line stage of it , but I have some doubts that OP is willing/able to do that ......
Thanks for the response...
I have tried some experiments with BoZ. Drain resistor is changed to 470R and source resistor is 47R. Gain approx. 20dB. Supply 60V regulated with improved Bosoz regulators. Drain current is close to 70mA and drain at half supply, so 2W power heats up the MOSFET...
Sound is very promising...I think this close to what I need
I have tried some experiments with BoZ. Drain resistor is changed to 470R and source resistor is 47R. Gain approx. 20dB. Supply 60V regulated with improved Bosoz regulators. Drain current is close to 70mA and drain at half supply, so 2W power heats up the MOSFET...
Sound is very promising...I think this close to what I need
QUOTE Drain current is close to 70mA and drain at half supply, so 2W power heats up the MOSFET...
......yes,you need a bigger heatsink on (all) the mosfets.power dissipation in the original boz is only around 20v x 40ma = 0,8w on the preamp mosfet.
i used irf510n in my boz and use it mostly with my tube poweramp.
greets
......yes,you need a bigger heatsink on (all) the mosfets.power dissipation in the original boz is only around 20v x 40ma = 0,8w on the preamp mosfet.
i used irf510n in my boz and use it mostly with my tube poweramp.
greets
Skorpio,
BoZ is a good preamp, but it's mostly a first step, not last. So, once you fiddled with it, forgetaboutit
Try this instead (see pic-Zen Mod copyleft)
Alternatively, you may wish to try this one:
The SSTART Preamplifier Why on earth would anyone do such a thing? Article By Grey Rollins
BoZ is a good preamp, but it's mostly a first step, not last
. So, once you fiddled with it, forgetaboutit Try this instead (see pic-Zen Mod copyleft)
Alternatively, you may wish to try this one:
The SSTART Preamplifier Why on earth would anyone do such a thing? Article By Grey Rollins
Attachments
Skorpio,
BoZ is a good preamp, but it's mostly a first step, not last
Try this instead (see pic-Zen Mod copyleft)
Alternatively, you may wish to try this one:
The SSTART Preamplifier Why on earth would anyone do such a thing? Article By Grey Rollins
Thank you for the alternative!
But I am running my F4 without the input buffer, so I like a lot of current...do you think your proposal will drive the MOSFET gates?
Also, CCS to maximize gain and then feedback to reduce it is not my preference...I like the simple approach. But the you will have to look at good PSU for optimal performance...
How would you describe the sound of your circuit compared to a BoZ?
To be honest, I never completed it, as I have built another amp (ZV9) which, driving hi-efficiency speakers, didn't need any additional gain at all, so I built a B1 and was happy.
But I had tried SEWA amp (a follower), and have driven it with Boz and Jfet Boz. Boz sounded a bit dry. On the other hand, original Jfet boz sounded fine, but didn't have enough gain so I went for completely different route...
It looks to me that (If you omit ZM's Pumpkin) Grey's SSart may be your best bet, but, not having heard it, I can't comment on the sound. Maybe someone else can...
Regards,
Vix
But I had tried SEWA amp (a follower), and have driven it with Boz and Jfet Boz. Boz sounded a bit dry. On the other hand, original Jfet boz sounded fine, but didn't have enough gain so I went for completely different route...
It looks to me that (If you omit ZM's Pumpkin) Grey's SSart may be your best bet, but, not having heard it, I can't comment on the sound. Maybe someone else can...
Regards,
Vix
That SSTART amplifier looks nice, just like a BoZ with a big JFET in the source. Makes me wonder...could one of the new power JFETs make it as alternative for the MOSFET in the BoZ?
I like the idea of plenty of current and low drain resistor, lots of drive and 20dB gain for F4, but will a power JFET do the job here? Mr. Pass wrote in the original BoZ and BosoZ articles that he had tried power MOSFET with acceptable results (high gate cap increase HF distorsion)...so it might på doable. The easy bias will be attractive, nice and simple
I like the idea of plenty of current and low drain resistor, lots of drive and 20dB gain for F4, but will a power JFET do the job here? Mr. Pass wrote in the original BoZ and BosoZ articles that he had tried power MOSFET with acceptable results (high gate cap increase HF distorsion)...so it might på doable. The easy bias will be attractive, nice and simple
Hmmmm, what is SS R550?
Another way could be using 5 pcs of 2SK170 i parallel, would it work? With IDSS of 10mA you could get 50mA of current...
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