Son of Zen and math

[oks81]

But still... the Vgs is only about 1,5V and up..

 

[moe29]

10 years a go i posted on this thread

SOZ is rad amp. SOZ is BIG amp! no getting around the need for dissipating lots of heat.

Mount power resistors on their own heat sink. Then FETS don't have to share. put a fan on them if needed. Big PSU too

i'll check back in another 10 years

 

[oks81]

Thanks for reply moe29!

Yes, its with SOZ as its with everything else.. "no free lunch"!

Looking forward to hear from you in 10 years! Maybe I have built a SOZ by then!

By the way, forget #41, it`s wrong!

 

[oks81]

So, tried "Half Son of Zen"
Had the parts, and did not take to long time to build

It plays music but should probably have 8ohm resistor instead of 10 and higher PSU voltge to get "sweetnes".
Know you guys in here said so, but had to give it a try!

Gain is also very low.

 

[Zen Mod]

roughly - ratio of resistance in drain vs. resistance in source is your gain

 

[oks81]

Spot on Zen!
Thanks a lot!

So got this schem from papa himself!
Thanks a lot to papa also!!

I named this one "Simply Zen"..

8ohm resistor is the speaker by the way!

Will give it a shot when I get time!

 

[oks81]

So tried the "Simply Zen"
Sounds better than "Half SOZ"

But have som hum.... Same hum in both speakers.

Any ideas?

 

[Zen Mod]

twist it up

and post some pictures

 

[oks81]

Pictures on PM

 

[Zen Mod]

got them

looking for magnifier glass

 

[oks81]

Sorry!
Can buy and ship directly!

3 LED Light 10x 20x Magnifier Handheld Reading Magnifying Glass Jewelry Loupe | eBay

 

[oks81]

got them

looking for magnifier glass

Think it`s PSU ripple making noise.
Maybe build CLC with big chokes to get ripple down.

Hum is not that loud, but nice to have a silent amp!

 

[Zen Mod]

just for test , double value of R in CRC

if that decrease hum , problem lies there , so you can attack it with chokes

 

[oks81]

Did go from 0,25ohm to 1ohm and it did help
Think CLC maybe next step, or I drop to much voltage in PSU

 

[mrWagner]

Use a RC filter for the 100k+47k resistors. Humm gets into the signal through those.

 

[oks81]

Use a RC filter for the 100k+47k resistors. Humm gets into the signal through those.

Ok, thanx!
But how without decreasing sound quality?

Best
oks

 

[mrWagner]

Sorry for my paint skills
100ohm, 100uF maybe
Why would it decrease sound quality? You are only filtering their supply.
Like at jlh, here a lot bigger resistor is used.
Possibly you could also use 1k or even bigger resistor for better filtering and bigger cap.

 

[oks81]

Thanks a lot mrWagner!!
Maybe we need both at least one year at art school!
I will take a look at it!!