Bride of Zen setup and suggestions

[Dinosauro]

Hello, I have realized a PCB oz Bride of Zen preamp. Before to connect it to my LM3886 chip amp, I ask if someone can chekup the values that I have measured. R104 is a 5W ceramic resistor but is temperature is too hot (that is normal?).
At the input, with no load, +0 V at the output I find some tension in slowly decrease (it's OK?).
I would like to connect ZEN to 100K log pot into my Gainclone amp: it's possible to do? I must put some resistor from C103 to ground (5k pot substitution).

Sorry, I speak a very bad English....

thanks

[mjf]

hello.
i think this preamp should work.but you can do some adaptations.
voltage drop at the source res (100 ohm) is 4v,so you have 40ma current trough the transistor.lower it a little bit ,down to around 3,5volt......3volt (gives 35ma.........30ma).this lowers the heat a little bit.

with a 100k pot at the output you should use short (= low capacitance) cable.or you will loose treble with a long cable.

voltage running up and down at the output: you measured it without a load(res).........or you have some (big) humming ,means wrong ground connection or something else.

the irf610 needs a heatsink.
greetings

[carpenter]

You can also get a quality resistor in TO-220 package and mount it to a heat sink--and yes, that mosfet needs a heat sink too.

[carpenter]

I just simmed that circuit. The drain resistor gets a little bit warm (like 1.1 watts), try mounting a heat sink to the resistor. Also, be sure to play with the pot; you can adjust the mosfet into a more favorable mode.

[carpenter]

Another thought about the drain resistor being too hot: is the mosfet blown?

[beetel]

Since this thread is related to BOZ.....

in BOZ 10 zeners are used in power supply and 20V zener in preamp circuit.
What is wattage of these zener diodes ? can we use 1/2 zener without any problem?

Another things is 5K log volume control which is hard to obtain. Can we use 10K here?

thanks

[mjf]

QUOTE=beetel
in BOZ 10 zeners are used in power supply and 20V zener in preamp circuit.
What is wattage of these zener diodes ? can we use 1/2 zener without any problem?

yes,you can use 1/2 watt zener diodes............

Another things is 5K log volume control which is hard to obtain. Can we use 10K here?

yes,i used a 10k pot (and i kept my audio cable short)...........and later on i paralelled a 10k res from pot output to ground.so it looks like a 5k pot a litte bit........
greetings

[Dinosauro]

Thanks, all works!
IRF610 burned, replaced; 4 Zener burned, replaced; 5W cemtent replaced with TO220 1% resistor. Trim source to 3.1 V. Added 10K pot on the output.

Many thanks!

[carpenter]

Good job!

[Dinosauro]

I want to add a phono stage for my DUALC S503-1. I find that circuit, but after build a prototype, the sound is very bad: distorted... a kind of "saturation with electric guitar". Where is the mistake: at the circuit or at the component chosen?
Resistor are film metal 1% (only 750 K are 2 parallel resistor 1M5 carbon), 6,8 n 1,5 n ceramic disc, 1 µF MKT (not polarized) and 10µF (ITT FKT).
I'm tried to throw it all away!
Suggestion?
SIGH!