Hello everyone and sorry for my bad English.
some time ago I bought the "JFET Boz" of JimsAudio that I would like to build. i have a transformer with double secondary (0-15V and 0-24v).
the 0-15v does go already the diamond buffer headamp of Sijosae.
now the question: the JFET Boz of JimsAudio can work with a voltage of 24V AC , if I am not mistaken, after the rectification bridge and filter capacitors will be 32-33v DC ?
Thanks in advance for any help.
rob
some time ago I bought the "JFET Boz" of JimsAudio that I would like to build. i have a transformer with double secondary (0-15V and 0-24v).
the 0-15v does go already the diamond buffer headamp of Sijosae.
now the question: the JFET Boz of JimsAudio can work with a voltage of 24V AC , if I am not mistaken, after the rectification bridge and filter capacitors will be 32-33v DC ?
Thanks in advance for any help.
rob
It depends of the bridge rectifier loss and your resistance value in your CRC PSU filter, but yes about 32V
Jims Audio PCB
I have got the PCB from Jims Audio, too. I just want to buy the necessary parts. In the part list of Jim is D6 not required. Therefore I just need a piece of wire, or?
On the photo at the website is just one Zener diode and not 4 as required in the part list or at the PCB! Has anyone assembled this PCB and can help?
Has anyone experience with this PCB and how is the quality of the power supply?
I have got the PCB from Jims Audio, too. I just want to buy the necessary parts. In the part list of Jim is D6 not required. Therefore I just need a piece of wire, or?
On the photo at the website is just one Zener diode and not 4 as required in the part list or at the PCB! Has anyone assembled this PCB and can help?
Has anyone experience with this PCB and how is the quality of the power supply?
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No, nothing on D6
In this photos I have replaced the diodes by a TL431 circuit (For fine tuning the V supply)
Hio Ramallo,
normally, I will need the 4 Zener diodes!
I think it's a little bit like gambling if the 16V fit to the Idss of the 2SK170.
Would be nice to have a Idss -> V - table to see what's the best voltage for the specific jfet if you have no oscilloscope.
normally, I will need the 4 Zener diodes!
I think it's a little bit like gambling if the 16V fit to the Idss of the 2SK170.
Would be nice to have a Idss -> V - table to see what's the best voltage for the specific jfet if you have no oscilloscope.
what a memory!
Nice idea with the little TL431 PCB! Does it work as you planned?
I'm considering to use 2 lead batteries for a phono pre so there would be enough power to drive the jfet boz and a DAC.
@tinitus: the chinese are copying anything. Not innovative but cheap.
Yes, work as planned 🙂 , with a distortion analyzer (Or a pc with a fft program) I can tune for the lowest distortion (0,5V can be the difference between 0,7% or 0,05%)
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz-104.html#post2574557
Actually is a copy of Manu's board
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz-16.html#post1231338
well, now you mention it, ripping off schematics that way, fast and easy, and you see what happens
but it sticks and could have ill effects, and be like poison poluting the forum
but no worry, you are not being blamed, not your problem
After reading the post from Tschrama with the table of Idss and voltage I have seen that my 2SK170 that I've got from a group buy have 4.9 mA so I can expect a THD of about 2% at around 8V.
I think it would be better to get new ones that have an Idss of about >8 mA! Anyone who can sell 4 or 8 pieces of them?
I think it would be better to get new ones that have an Idss of about >8 mA! Anyone who can sell 4 or 8 pieces of them?
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Asking Too Much
I'm asking too much out of my BOZ-J. With 16v supply, it's driving a MOX II and F5 and SIT 5w amp.
I don't really want a new preamp right now. I like the BOZ-J and what it can do. I'd like to increase the power supply without increasing distortion, and further still, keep it in the "sweet spot".
I don't have a distortion analyzer, so anyone who has build a BOZ-J with a higher supply, what have you found to be a good setting of votage and current?
Thanks,
Vince
I'm asking too much out of my BOZ-J. With 16v supply, it's driving a MOX II and F5 and SIT 5w amp.
I don't really want a new preamp right now. I like the BOZ-J and what it can do. I'd like to increase the power supply without increasing distortion, and further still, keep it in the "sweet spot".
I don't have a distortion analyzer, so anyone who has build a BOZ-J with a higher supply, what have you found to be a good setting of votage and current?
Thanks,
Vince
I run mine on 27V with no problems. I like the sound too but lately have found a 6N7 tube based preamp I just finished to have better bass and sound stage. But as a dead simple low distortion preamp they can't be beat.
Thanks mhouston. What did you use on the source resistor?
Currently using 22 ohm with 16v.
Thanks,
Vince
Currently using 22 ohm with 16v.
Thanks,
Vince
Was able to get the voltage up to 26v by changing 1 resistor on the LM317 regulator.
sounds nice!
sounds nice!
Can anyone post the voltage that is needed to drive my 2SK170s with 4.9mA Idss to lowest distortion? I don't have any measurement equipment for this and my ears are too old and used to decide it by sound. 🙁
With a pc, a sound card and a fft program you can measure the distortion.
http://www.diyaudio.com/forums/mult...basic-dumb-free-fft-measurement-software.html
Just with a sinus tone at the preamp input (for example 1 kHz) and the preamp output connected to "line in" of the sound card, you can see the tone and his harmonics. You need just move the value of the voltage supply for get the lowest harmonic amount