Pass "DeLite" Amp from BAF

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Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
Nelson Pass said:
Obviously I built the circuit of Fig 7, and it works as described.

If you use a part with a different Vgs figure, then it needs to be adjusted.

:cool:
Click to expand...

FROM ARTICLE
"To give you a taste of what to expect from even better transistors coming out of the labs these days, I have a distortion curve from a part which is not yet on the market but which you will eventually be able to drop right in. Figure 12 shows a depletion mode power JFET placed in the circuit of Figure 7 but with an 80 volt supply."

Also see a schematic I think I robbed from Tony Wong. Not sure what his bulb resistance was.

 
V

vtr

Member
Joined 2010
thanks

to mr pass and teabag,

so first-i have been too stupid to calculate Ueff correct-circuit delivers now around 9W in the setup as shown.

then connected my preamp to drive the fet better and i recieved a nice sound-:)

@Mr.Pass-as written in the delite manual 1,8A is a good sweet spot fot this device and what Uds shall i look for?

and as design idea what do you think is the better approach -a one stage design with r085 and choke loaded and a low output Z preamp (my allen wright RTP does this quite well) or

a follower output stage again choke loaded (i like the einstein approach to have the choke also working as bias resistor in union)
and a extra gain stage with 2sk170 but more work to have the required voltage swing.

thx´s
 
Tea-Bag

Tea-Bag

Member
Joined 2006
Paid Member
stefanobilliani said:
By the way this is how my JFET amp prototype looks like , this time with the light bulb .
The light bulb I believe is about 18 ohm or so .
It sound very good , probably better in my taste than the CCS version , don't know really .
The voltage now is 30 volts , and I am wondering how high it can be set .

thanks
Click to expand...

Well, I finally got around to modding my de-lite a bit using your hard work as my guide.;)

I am running a 8R 300W light bulb, 55volts to the lightbulb. 1.3v across R1, and -7v at the gate to get it to sing I have 50R 50W across the output. Adding anymore dims the Lightbulb down to nothing. :confused:


The sound is a bit tangy compared to the R100 sound in this circuit. I am sure it needs more work to get it sounding it's best. I will have to try tuning more with headphones.


I am thinking I will order some halogen sticks and sockets to play with those.

Now I got to think through modding my F3 with some of these mods and see where it goes.
 
S

stefanobilliani

Member
Joined 2002
Hello All , I have a little question .
I am just trying a version with the depletion Jfet and the light bulb .
Also a little feedback loop resistor from Drain to gate .
These are the values :
R, light bulb 15 ohm
I, 2 amps
Vgs, -5,3 volt
Vds 30 Volt
Vdd 60 volt .


Is that ok? or the current is too strong for the D-Jfet ?

Thanks
 
D

DIYer Straits

Member
Joined 2003
Hi Mr. Pass and you guys over here
This is my first post in this thread and I have been following diligently with the Delite amp and its various permutations. ;D I have decided to plunge in after listening to Tony Wong's creations and loved the sound that the Delite can give. However, the light bulb I can live without as I prefer to listen in the dark. A 1000W bulb is a leeetle bit too bright for my liking. Glowing tubes like the SV811/572/211/845 I can live with and I have. The Delite CCS is a Godsend!
Now, after following Sgr Steffanobillani's CCS circuit on page 61 post #605 to the letter, I have this little problem, I am unable to get half the rail voltage (40V DC) at Q1's drain. Q1 source is 1.8V, Q2 source is 34.7V, Q1 drain is 31.5V. Adjusting R7 doesn't seem to do anything except vary the voltage between R7 and R10 from 34V to 23V. How do I bias Q2? My creation is posted in this forum here.[url/]
 
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