Pearl Two

[juma]

.... I just use the SK170 and I like to try a substitute with higher Gfs.

This is the graph from 2sk170's datasheet. It shows a correlation between Idss and transconductance. Look at it carefully and be aware that 2sk170 comes in three Idss groups (GR, BL and V), ranging from 2.6mA to 20mA...

 

[jacco vermeulen]

N-Channel JFet with Gfs above 22mS?

2SK369V

 

[Joao@AltheaMusica]

Thanks Jacco & Juma

 

[juma]

2SK369V

They price it 11.5 CHF (11.4 US$) a piece???

Same Yfs as BF862 but 7.5 times higher Ciss and 5 times higher Crss with 40 times higher price - not a good deal at all...

 

[Zen Mod]

but they're ooking fancy

aren't they cascoded in Oyster's Brat 2 ?

 

[juma]

but they're ooking fancy

That justifies anything...

....Oyster's Brat 2 ?

What's that ?
Does it look like this :

 

[Zen Mod]

The World Is My Oyster lyrics

[Mostly instrumental]

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

The world is my oyster
Ha ha ha ha ha ........

Yeah yeah

 

[jacco vermeulen]

a piece?

No Pain, no Gain.

(i've always wondered why having oysters is considered foreplay)

 

[juma]

Yeah, the pain is also considered a foreplay by some...

 

[Zen Mod]

wacoo geezers



I'm shuddering

 

[Salas]

Are you going to play Tainted Love on that all day long?

 

[mlloyd1]

so, has anybody finished building yet?

mlloyd1

 

[basaltguy]

Just a dumb question. Are 1/8 watt resistors adequate? Also, does anyone have any specific advise about what caps to use. Any assistance will be greatly appreciated. Thanks.

 

[Rudymay1945]

Pearl Two Problem

Guys, just finished the pearl two using Pass boards and I have a problem.

Power supply is in a separate box. It checked out ok. But when I connect it to the circuit chassis strange things happen. On turn on things sound fine but within a couple of minutes the volume fades away.

When I checked out the voltages, the positive supply rail at R4 starts dropping from 24.06 volts to around 5.74 volts in about two minutes. The negative rail goes up to 62.1 volts.

This happens with both boards whether one or both are connected to the power supply.

Any suggestions? I have checked the layout and it looks ok. I'm not a techie so I'm a little lost.

Thanks
Rudy

 

[Tea-Bag]

DC offset?

 

[Rudymay1945]

DC offset

Around 30mv at the P1 test point and 1mv at the output.

 

[gotoma8]

Question...about listing...

Those interested, I've listed in the "Swap Meet" a set of Pearl 2 boards I got, with matching FETs. If interested, pleaes let me know.
Thanks
T

 

[BDP]

What's the voltage at the regulator input?

 

[Rudymay1945]

Pearl two issue

Starts off at +24 volts then drops to +5.74v, starts at - 24 and increases to -62.1v. Takes less than 90 sec to do this. Also noticed some popping sounds during this period.

Thanks
Rudy

 

[Rudymay1945]

Correction

Sorry, at power on, the input to regulators is + and - 35 volts. It changes to the 5 and -64 volt quickly.