hi mads, thanks for your reply, no l am not greedy l just want to use the traffo up and build that sweet little amp that l heard in hungary...... my fave place to be in summer...... especially meeting nice people there like tyimo[ norbert]
and being surprised by their enthusiasm and knowledge for and about all things audio [ real hi-fi
] cheers and thanks for your responses TC
[P.S] szia norbert és zoltán bocs hogy elöb elfelejtettem üdvözölni beneteket![translation: hi norbert and zoltán, pardon me for forgetting to greet you earlier]
can I put another maybe two 1 ohm in paralell with R12-R16?This will maybee get me closer to 10w or?
BOZ with 2SK216
Hi Mads!
I need your help!
I finished my new BOZ (your version) today with 2SK216 Fets.
Everything is O.K. The Led is on! The amp is working!
I measured the voltages on the testpoints:
DCreg =62.8V
Gate V = 5.07 Vdc
Drain V = 18.73 Vdc
Source V = 4.0 Vdc
These values are different from the original BOZ with the IRF610, but I think it is because the 2SK216 has different Vgs.
IRF610 Vgs= 4V max.
2SK216 Vgs=1.5V max.
My question:
What do you think which values need I adjust?
I mean should I adjust the Source to be 4Vdc or the Drain to be 20Vdc?? What is the most imprtant???
Tonight I would like to test the amp with music!
Greets:
Tyimo
Hi Mads!
I need your help!
I finished my new BOZ (your version) today with 2SK216 Fets.
Everything is O.K. The Led is on! The amp is working!
I measured the voltages on the testpoints:
DCreg =62.8V
Gate V = 5.07 Vdc
Drain V = 18.73 Vdc
Source V = 4.0 Vdc
These values are different from the original BOZ with the IRF610, but I think it is because the 2SK216 has different Vgs.
IRF610 Vgs= 4V max.
2SK216 Vgs=1.5V max.
My question:
What do you think which values need I adjust?
I mean should I adjust the Source to be 4Vdc or the Drain to be 20Vdc?? What is the most imprtant???
Tonight I would like to test the amp with music!
Greets:
Tyimo
Re: BOZ with 2SK216
Hello old friend Tyimo
I attach the schematic of the original ZEN PREAMP = BOZ, Bride Of Zen.
So we know what we are talking about.
As I can remember the 2SK216, if can be found from some supplier, can be an upgrade of IRF610.
It is a very good little MOSFET with good qualities for audio applications!
I should Keep R108 at 100 Ohm
and only adjust the trimpot to get 20 Volt at 2SK216 DRAIN.
Because the VOLTAGE GAIN is the ratio of R104/R108= 1k/100 = 10.
So I would not change R108, unless I would need More or Less gain.
----------
The actual voltage gain with a load it will be a bit less than 10,
with a load at output
and as MOSFET has a little drop in Vgs, and can never get near to gain=1.
So AC Voltage across R108 will be a little bit less than input signal
and output voltage (at DRAIN) will be roughly 10x this signal at MOSFET SOURCE.
----------
The total voltage gain of BOZ, from input to output,
I should estimate to be like GAIN ~8.
This is if you use a 5000 Ohm Potentiometer at output.
Here is Nelson Pass original description of BOZ
http://www.passdiy.com/pdf/brideofzen.pdf
Attached is the schematic of this first Zen Pre-Amplifier.
lineup
Tyimo said:I need your help!
I finished my new BOZ (your version) today with 2SK216 Fets.
Everything is O.K. The Led is on! The amp is working!
I measured the voltages on the testpoints:
DCreg =62.8V
Gate V = 5.07 Vdc
Drain V = 18.73 Vdc
Source V = 4.0 Vdc
These values are different from the original BOZ with the IRF610, but I think it is because the 2SK216 has different Vgs.
IRF610 Vgs= 4V max.
2SK216 Vgs=1.5V max.
My question:
What do you think which values need I adjust?
I mean should I adjust the Source to be 4Vdc or the Drain to be 20Vdc?? What is the most imprtant???
.
Hello old friend Tyimo
I attach the schematic of the original ZEN PREAMP = BOZ, Bride Of Zen.
So we know what we are talking about.
As I can remember the 2SK216, if can be found from some supplier, can be an upgrade of IRF610.
It is a very good little MOSFET with good qualities for audio applications!
I should Keep R108 at 100 Ohm
and only adjust the trimpot to get 20 Volt at 2SK216 DRAIN.
Because the VOLTAGE GAIN is the ratio of R104/R108= 1k/100 = 10.
So I would not change R108, unless I would need More or Less gain.
----------
The actual voltage gain with a load it will be a bit less than 10,
with a load at output
and as MOSFET has a little drop in Vgs, and can never get near to gain=1.
So AC Voltage across R108 will be a little bit less than input signal
and output voltage (at DRAIN) will be roughly 10x this signal at MOSFET SOURCE.
----------
The total voltage gain of BOZ, from input to output,
I should estimate to be like GAIN ~8.
This is if you use a 5000 Ohm Potentiometer at output.
Here is Nelson Pass original description of BOZ
http://www.passdiy.com/pdf/brideofzen.pdf
Attached is the schematic of this first Zen Pre-Amplifier.
lineup
Attachments
Hi Lineup master!
Thanks for the answers!!
Yes, I will keep it and try to get the 20V drain and see how much will be on the source.
Is a 10K pot on the out put too much?? I know the 5K is the perfect, but I have a nice one 10K in my hand.
You didn't answered to my question about to use Lovoltech Jfets for preamp in ZV9 style! Basicaly it was your idea...
Greets:
Tyimo
Thanks for the answers!!
Yes, I will keep it and try to get the 20V drain and see how much will be on the source.
Is a 10K pot on the out put too much?? I know the 5K is the perfect, but I have a nice one 10K in my hand.
You didn't answered to my question about to use Lovoltech Jfets for preamp in ZV9 style! Basicaly it was your idea...
Greets:
Tyimo
Tyimo said:
Is a 10K pot on the out put too much?? I know the 5K is the perfect, but I have a nice one 10K in my hand.
You didn't answered to my question about to use Lovoltech Jfets for preamp in ZV9 style! Basically it was your idea...
About using any other JFET in same configuration as in ZV9,
it was not such good idea.
I did see right after I posted, it wouldn't work!
Better forget about that one ....
##########################
Actually after my last post ( before you asking ),
I thought I should have added:
... a suggest to use a bit HIGHER value Volume Potentiometer, if possible.
My choice would be 22 kOhm or even 47 kOhm.
There are a couple of good reasons for this:
----------------
1. The higher value, in ohms, the load have
the less current it will take from preamp output.
It is AN EASIER LOAD.
The preamp will have lower distortion with light loads
and also have a tiny bit more gain ( getting closer to 10, from that Gain=8 )
An often used rule, that is reasonable and any works well in most cases:
Load should have at least 10 times higher impedance than amplifier output impedance
Output impedance is in BOZ case 1.000 Ohms, set by R104 (1kohm).
Following this rule we get load (potentiometer) should be
10 kOhm or more!
---------------------
2. When using 5 kOhm pot, we need to have maybe at least 10 uF output capacitor.
And getting a good filmcap ( MKT polyester, or MKP Polypropylene ) that 'high' value is not easy. = Cost money!
I do not want to recommend electrolytic output cap, not in any case where we could use filmcaps!
Not even any of those infamous so called Black Gate Electrolytic Capacitors can match any sort of filmcaps
when it comes to DISTORTION and other good audio parameters.
By using 10 kOhm potentiometer, you can get a good very low frequency ( 10-50 Hertz ) behavior
using only a 2.2 - 4.7 uF filmcap as output capacitor.
For 10 kOhm potentiometer I would probably try to find a 4.7uF
and for 22 kOhm pot I might be happy with 2.2uF.
2.2 uF film capacitors are not difficult to find and buy to a reasonable price.
There is also possibility to parallel two or even more 2.2 uF ( = 4.4 uF ) if you cant find one 4.7 uF.
Three 2.2 uF in parallel will be same as one 6.6 uF.
Two 1.0 uF will be equal to one 2.0 uF.
lineup
Re: BOZ with 2SK216
You should adjust for 25V at the drain for maximum output swing (needed to drive SEWA). Y
Tyimo said:Hi Mads!
I need your help!
I finished my new BOZ (your version) today with 2SK216 Fets.
Everything is O.K. The Led is on! The amp is working!
I measured the voltages on the testpoints:
DCreg =62.8V
Gate V = 5.07 Vdc
Drain V = 18.73 Vdc
Source V = 4.0 Vdc
These values are different from the original BOZ with the IRF610, but I think it is because the 2SK216 has different Vgs.
IRF610 Vgs= 4V max.
2SK216 Vgs=1.5V max.
My question:
What do you think which values need I adjust?
I mean should I adjust the Source to be 4Vdc or the Drain to be 20Vdc?? What is the most imprtant???
Tonight I would like to test the amp with music!
Greets:
Tyimo
You should adjust for 25V at the drain for maximum output swing (needed to drive SEWA). Y
Re: Re: BOZ with 2SK216
Same thinking as I have, Mad_K!
Very good advice!
---------------------
When Nelson set the original output voltage for BOZ
he may have had this thinking:
Hmmm, 60 VDC .. think I put 20 Volt drain-source across IRF610
and twice as much across the R104 ( 1k ) resistor.
And this is good thinking,
and works almost optimal as long as the output voltage is not more than 6-8 VRMS.
Now with original circuit we have:
R104 = 40 volt
IRF610 = 16 volt
R108 = 4 volt
SUM = 60 Volt ( Output is at 16+4= 20 Volt )
8 VRMS = 1.414 x 8 = 11.3 Volt AC peak swing
As the MOSFET has only 16V at average
this means at full 11.3V output a
and also is a swing of (11.3/gain) across R108 (100 Ohm)
will be only 16 -11.3 -(11.3/8) = 3.3 Volt left across mosfet.
This is low for a 2SK216, it may get into saturation region ( the non-linear region of mosfet curve)
and start 'wanting more air to breathe'.
########################
As you, Tyimo, have 62 Volt to spend, I would suggest you follow Mad_K good advice:
Set the DRAIN Voltage of 2SK216 at 25.0 VDC
will give approximately the following result,
at 62 VDC supply:
R104 - 1kohm = 37 Volt
2SK216 - mosfet = 21.3 Volt
R108- 100 Ohm = 3.7 Volt
SUM = 62.0 Volt ( Output at 21.2+3.7= 25 Volt )
Now if we put out same 8 VRMS (11.3 Vpeak)
we still have 8.6 V across the lonely 2SK216 MOSFET
and this is a much better value, operation margin,
and a good chance this transistor will still operate in its LINEAR REGION = lower distortion and no clipping tendency.
Maths in this post done by Lineup Audio Lab
chief designer
lineup
Mad_K said:
Same thinking as I have, Mad_K!
Very good advice!
---------------------
When Nelson set the original output voltage for BOZ
he may have had this thinking:
Hmmm, 60 VDC .. think I put 20 Volt drain-source across IRF610
and twice as much across the R104 ( 1k ) resistor.
And this is good thinking,
and works almost optimal as long as the output voltage is not more than 6-8 VRMS.
Now with original circuit we have:
R104 = 40 volt
IRF610 = 16 volt
R108 = 4 volt
SUM = 60 Volt ( Output is at 16+4= 20 Volt )
8 VRMS = 1.414 x 8 = 11.3 Volt AC peak swing
As the MOSFET has only 16V at average
this means at full 11.3V output a
and also is a swing of (11.3/gain) across R108 (100 Ohm)
will be only 16 -11.3 -(11.3/8) = 3.3 Volt left across mosfet.
This is low for a 2SK216, it may get into saturation region ( the non-linear region of mosfet curve)
and start 'wanting more air to breathe'.
########################
As you, Tyimo, have 62 Volt to spend, I would suggest you follow Mad_K good advice:
Set the DRAIN Voltage of 2SK216 at 25.0 VDC
will give approximately the following result,
at 62 VDC supply:
R104 - 1kohm = 37 Volt
2SK216 - mosfet = 21.3 Volt
R108- 100 Ohm = 3.7 Volt
SUM = 62.0 Volt ( Output at 21.2+3.7= 25 Volt )
Now if we put out same 8 VRMS (11.3 Vpeak)
we still have 8.6 V across the lonely 2SK216 MOSFET
and this is a much better value, operation margin,
and a good chance this transistor will still operate in its LINEAR REGION = lower distortion and no clipping tendency.
Maths in this post done by Lineup Audio Lab
chief designer
lineup
New BOZ on the run
Hi Mads and Lineup, my black belt Zen Masters!
I report you that my new "Tuning-BOZ" is working!!!
Everything worked since the first turn on, no "humm", no "hiss" and no "smoke"....just music!
I didn't make a real listening test between the original BOZ and the T-BOZ and the amp is not burned in yet (unfortunately my wife is at home.... ) ,but here are my first listening impressions after one hour:
The sound is very serious, warm and wooooly, but also very-very detailed!! I can "eat" the sounds or I could say the sound has full body and form. It has very much power and can drive the SEWA better than the BOZ! The vocals are awesome good!
I can only recomend to build Mads BOZ with 2SK216!!!! 
Techs infos:
- 62Vdc RegV
- 3.46Vdc on Source
- 25Vdc on Drain
- 4.43 on Gate
Parts are non esoterics
2x30V 50VA toroid
2SK216
1uF/100V Siemens Mica input cap
10uF/100V ERO MKT output cap
Yageo 1% 0.5W metalfim resistors
Now I donn't use pots because my Yamaha CDX993 has an output pot, but later I will try the 10K pot on the output.
Next week I will make a real listening test with the BOZ and the T-BOZ and maybe with some tube preamps, if I will ready with them.
So, I would like to say thanks to Mads and Lineup (and donn't forget to Mr. Pass! ) for all the help I got from you!!! I realy learnt a lot from you! Thank you very much!!!
Now I would like to ask Mads:
-Which PCB designer program did you use for the PCB? I would like to redesign the BOZ PCB for the 2SK216 pins (GSD) and for a different trimmer pot if it is possible.
-Donn't you want to make an integrated design and PCB for the BOZ-SEWA combo???? That would be
Greets:
Tyimo
Hi Mads and Lineup, my black belt Zen Masters!
I report you that my new "Tuning-BOZ" is working!!!
Everything worked since the first turn on, no "humm", no "hiss" and no "smoke"....just music!
I didn't make a real listening test between the original BOZ and the T-BOZ and the amp is not burned in yet (unfortunately my wife is at home....
) ,but here are my first listening impressions after one hour:The sound is very serious, warm and wooooly, but also very-very detailed!! I can "eat" the sounds or I could say the sound has full body and form. It has very much power and can drive the SEWA better than the BOZ! The vocals are awesome good!
I can only recomend to build Mads BOZ with 2SK216!!!!
Techs infos:
- 62Vdc RegV
- 3.46Vdc on Source
- 25Vdc on Drain
- 4.43 on Gate
Parts are non esoterics
2x30V 50VA toroid
2SK216
1uF/100V Siemens Mica input cap
10uF/100V ERO MKT output cap
Yageo 1% 0.5W metalfim resistors
Now I donn't use pots because my Yamaha CDX993 has an output pot, but later I will try the 10K pot on the output.
Next week I will make a real listening test with the BOZ and the T-BOZ and maybe with some tube preamps, if I will ready with them.
So, I would like to say thanks to Mads and Lineup (and donn't forget to Mr. Pass! ) for all the help I got from you!!! I realy learnt a lot from you! Thank you very much!!!
Now I would like to ask Mads:
-Which PCB designer program did you use for the PCB? I would like to redesign the BOZ PCB for the 2SK216 pins (GSD) and for a different trimmer pot if it is possible.
-Donn't you want to make an integrated design and PCB for the BOZ-SEWA combo???? That would be
Greets:
Tyimo
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.