Jfet BOZ

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Joined 2005
thanks !

at first it had so much overdrive, and it distorted way too easy
now it does not sound distorted at all
it can still be pushed into overdrive, but only very very mild...and really sweet
but I still have a stereo unity gain buffer with attenuation between this and my big solid state 150watt hifi poweramp, or else it gets too much

but I'm very happy with the 'small stuff' I have learned from this
a break, and then on to the next project
cheers
 
I am attempting to point to point a jfet boz.

I forgot to order the 475 ohm resistors on the output. Can a higher or lower value be used here? I have some 1K's and 910ohms I could parrallel up I guess for about 450 ohms.

Thanks.
 

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I am attempting to point to point a jfet boz.

I forgot to order the 475 ohm resistors on the output. Can a higher or lower value be used here? I have some 1K's and 910ohms I could parrallel up I guess for about 450 ohms.

Thanks.
Mate just use 1k or anything close. The preamp probably loads into a minimum of a 10k load. 450ohms or 1k it really doesn't matter.
 
Almost done. I doubled up two 1K's for the output.

I plan on using batteries like the diagram attached. Probably wont use any PS caps or maybe 1,000 UF or so.

Question: Should I just run the Pot/RCA grounds to the copper ground "buss" in the middle of the caps?
 

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Heres some pics, kind of a mess but you will get the idea.

All the RCA rounds and pot grounds are going to the copper "bus" between the caps.

Powered up, I only have .3V between D-G on the jfets. I've got 19V before the 2.2K V+ resistor and .3V after it.

Thanks for the help.
 

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Putting the volt meter across the 2.2k, Pos. meter lead on the 19v side and the Neg. lead on the drain side, what's the voltage reading? Check the value of the 2.2k with unit powered off. What's value of the Source side resistor? Check orientation of jfets as well.

Do you have spare 2sk170 jfets?
 
Putting the volt meter across the 2.2k, Pos. meter lead on the 19v side and the Neg. lead on the drain side, what's the voltage reading? Check the value of the 2.2k with unit powered off. What's value of the Source side resistor? Check orientation of jfets as well.

Do you have spare 2sk170 jfets?

I've got 19V+ across the 2.2K. The 2.2K measures 1.2K with the unit powered off. Verified the source side resistor is 10ohm.

I am suspecting the jfets.
 
Oh man. I had made a stupid mistake.

I had just bought a thrift store DMM before assembling the jfet boz. I didnt realize the leads were plugged in backwards. I was delivering -19V NEGATIVE through the power supply. Stupid.

Well, I realized this, swapped the battery leads and...IT WORKS.

But it doesn't sound so good. It has lots of gain but it sounds a bit distorted and the soundstage is small. I will investigate further...