Bride of Zen used as a buffer.

[beppe61]

Dear Sirs,

I wonder if taking the signal out of the mosfet source in the BOZ it will work as a unity gain buffer.
What would be the output impedance of this solution ?
Anyone has already tried this solution ? How nice is the sound ?
I do not need any voltage gain in my system but I have a very tough load (5K) to drive.
I have already a BOZ to use but I am also open to other simpler solution based on fet/mosfet buffer.


Thank you very much indeed.
Kind regards,

beppe

 

[Vix]

Yes, it is possible, and it will work in much the same way as the buffer in ZEN V4 does.

To do this you have to remove bias resistors (R101, P102, R103, R105), . Remove R108 as well. Also remove C102 and input cap C104. Most important, replace the mosfet with the IRF 9610 ( P Type).

Drain goes to ground and you take the signal out of the Source pin, via output cap. C103. If you operate it with 60 V supply and use R104 at 1 Kohm , it should have around 56 V through it, or 56 mA current.

Let us know how it sounds.

Vix

 

[beppe61]

Yes, it is possible, and it will work in much the same way as the buffer in ZEN V4 does.
To do this you have to remove bias resistors (R101, P102, R103, R105), . Remove R108 as well. Also remove C102 and input cap C104. Most important, replace the mosfet with the IRF 9610 ( P Type).
Drain goes to ground and you take the signal out of the Source pin, via output cap. C103. If you operate it with 60 V supply and use R104 at 1 Kohm , it should have around 56 V through it, or 56 mA current.
Let us know how it sounds.
Vix

Thank you very much for your kind reply.
Is it not possible to leave everything as it is and just take the signal out from the mosfet source ?
I would like to compare the sounds from the original and the buffer.
Or better, Where could I find a working schematic for a buffer based on just a single mosfet ?
Maybe even with lower voltage supply.
From what I understand if I lower R104 I could go with a lower voltage.
The best would be with max 30 V because I already have a really nice 30V single power supply I could use.
Could you kindly give me some more hints about a schema suitable for the IRF 9610 you mention and a 30 V power supply ?
That would be just perfect for my needs.
In this way I could leave the present BOZ for other purposes.
Thank you very much again.
Kind regards,

beppe

 

[flg]

beppe61, First, Don't call me sirs Second, A few years back I needed a quick and dirty(only a phrase) volume buffer type thing... I built the schemo pictured(attached)... It worked good... I still have it... I could not find anything but paper so I redrew it for you... Just an idea
You might want a little more C on the output to drive A 5K input... Maybe 10-47uF...
Oh, I forgot to mention,,, The reason it has a 42V supply is that there are millions of printers being thrown in the trash that have a 42 Volt SMPS supply in them. After a little filtering you wont hear anything...
A few more little omissions, the mosfet P is a ZVP3310A (What Else?) And, there is actually a 100 ohm in series with the output

 

[beppe61]

beppe61, First, Don't call me sirs
Second, A few years back I needed a quick and dirty(only a phrase) volume buffer type thing...
I built the schemo pictured(attached)... It worked good...
I still have it...
I could not find anything but paper so I redrew it for you... Just an idea
You might want a little more C on the output to drive A 5K input... Maybe 10-47uF...
Oh, I forgot to mention,,,
The reason it has a 42V supply is that there are millions of printers being thrown in the trash that have a 42 Volt SMPS supply in them.
After a little filtering you wont hear anything...
A few more little omissions, the mosfet P is a ZVP3310A (What Else?)
And, there is actually a 100 ohm in series with the output

A few years back I needed a quick and dirty(only a phrase) volume buffer type thing.... It worked good....so I redrew it for you...
Thank you very much.
I was thinking about something even more "quick and dirty" actually.
A single mosfet buffer with a very basic power supply, something to build on a small board.
I can do without voltage gain. I need just a good sounding driver stage for a 5K load (my mono amps) that I quite like


The reason it has a 42V supply is that there are millions of printers being thrown in the trash that have a 42 Volt SMPS supply in them.
After a little filtering you wont hear anything
This is extremely interesting. Thank you for the advice.
Do you think that a passive (R-C) filtering should suffice ?

the mosfet P is a ZVP3310A (What Else?)
Do you mean that it is the best choice speaking of P mosfet?
Is it a common part everywhere (I live in Italy)?
I already have some IRF610 at hand anyway.

Thanks a lot and kind regards,

beppe

 

[flg]

beppe61, Lets see, Quicker and simpler, could be the omission of the current source and replacing it with a resistor. The circuit I posted has about 34mA Iq and 22.5 Volts after the CRCRC. You could use 500-600 ohms to replace the Isource. Might be better to reduce some of the first 600 ohm in the input filter, maybe down to 100 ohms or so, and then you can use a value like 1K or so to replace the Isource... I don't think it's all that critical...

Filtering the SMP with just a film cap makes a tremendous difference. A little more filtering can't hurt. A little physical distance, between the supply and the signal is a good idea also. Most of 'em are good for about an Amp...

I don't know if the Zetex ZVP3310A is availble over in your part of the world? It is a common transistor to the Pass DIYers. And it's a good little part

In the case you did not notice, this is basically the buffer from the ZV4 project

 

[beppe61]

beppe61,
Lets see, Quicker and simpler, could be the omission of the current source and replacing it with a resistor.
The circuit I posted has about 34mA Iq and 22.5 Volts after the CRCRC. You could use 500-600 ohms to replace the Isource. Might be better to reduce some of the first 600 ohm in the input filter, maybe down to 100 ohms or so, and then you can use a value like 1K or so to replace the Isource...
I don't think it's all that critical...
Filtering the SMP with just a film cap makes a tremendous difference. A little more filtering can't hurt.
A little physical distance, between the supply and the signal is a good idea also. Most of 'em are good for about an Amp...
I don't know if the Zetex ZVP3310A is availble over in your part of the world? It is a common transistor to the Pass DIYers.
And it's a good little part

Quicker and simpler, could be the omission of the current source and replacing it with a resistor
After all I think it would be better to stich with the original schematic you propose, as it is tested, instead of introducing any mods.

In the case you did not notice, this is basically the buffer from the ZV4 project
Thanks for the info. I will look for that project then.
Kind regards,

beppe