But the ebay seller for FT-3 0.1uf lives in the same area with me so shipping free 🙂
Also, i have some Vishay Dale metalfilm available. Would be good to use those Dales or some carbons ?
Fighting a slight trouble with hum, I finally got rid of it with the help of some judicious GND arrangements.
It is incredible the difference it makes in overall presentation, detail, stage... superb.
One thing I must stress here... this new 58dB build is really silent.... At full blast I can hardly hear a soft hiss when I place my ears 10cm from the speakers.
Now I must get a propper metal case and start upgrading some components...🙂
It is incredible the difference it makes in overall presentation, detail, stage... superb.
One thing I must stress here... this new 58dB build is really silent.... At full blast I can hardly hear a soft hiss when I place my ears 10cm from the speakers.
Now I must get a propper metal case and start upgrading some components...🙂
You did not tell me, how much voltage across lower buffer JFET?
Yes, the Ampex papers were showing same repro amp curve for both 7 1/2 & 15 ips speeds.
11v... do you believe there might be some sonic benefits by increasing the drain resistor to 1800 ?
Not really, I took it to 1800 for when the BF245 went so to have ~22/2 across each buffer JFET for design elegance. That's in conjunction with the IDSS of the lower buffer JFET. If you will be rebuilding component quality and is handy try make the voltage 22V after the resistor with proper value judged in your build. If you will be able to discern anything better it can only be a plus. What it practically does is it equalizes the dissipation on the buffer JFETs.
P.S. Not drain resistor, RC filter resistor for buffer stage.
P.S. Not drain resistor, RC filter resistor for buffer stage.
You are right... this is a buffer, not a common source amp 🙄
I will take the 22v in consideration when I upgrade... thank you 🙂
In this case I should use 1k6 to drop 22v because Idss (calculated) is 7.95mA
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Hi FET fans !!!
The postman got here from China today ( he looked exhausted ! )...
...with a 'test' of 10 Toshiba K170-BL...
...from eBay seller 'Polida'.
The JFET's were supplied loose, with straight-legs ( as per sellers photo )...
...and the 'typography' on the bodys was also the same 'style' as the eBay photo.
They have 'visible copper' at lead-out & no marking in rear-dimple.
It does look like they may be from several batches...
...as there are some different suffix-suffix's ( eg. after K170-BL ( factory run code )).
They are all within the Toshiba spec. for BL ( blue ) devices ( 6-12mA ).
Here's what I got...
10.76
10.52
10.36
10.35
10.21
9.36
8.45
7.84
7.23
6.70
All tested with simple new 9 Volt battery & good-meter...
...left to 'settle' for about 2 mins each.
Can't complain I suppose...
...any thoughts or comments, anyone ?
Cheers
Si.
The postman got here from China today ( he looked exhausted ! )...
...with a 'test' of 10 Toshiba K170-BL...
...from eBay seller 'Polida'.
The JFET's were supplied loose, with straight-legs ( as per sellers photo )...
...and the 'typography' on the bodys was also the same 'style' as the eBay photo.
They have 'visible copper' at lead-out & no marking in rear-dimple.
It does look like they may be from several batches...
...as there are some different suffix-suffix's ( eg. after K170-BL ( factory run code )).
They are all within the Toshiba spec. for BL ( blue ) devices ( 6-12mA ).
Here's what I got...
10.76
10.52
10.36
10.35
10.21
9.36
8.45
7.84
7.23
6.70
All tested with simple new 9 Volt battery & good-meter...
...left to 'settle' for about 2 mins each.
Can't complain I suppose...
...any thoughts or comments, anyone ?
Cheers
Si.
i find polida as a seller on ebay, but they have not sold anything like 2sk170, last sale in 2007
and they are listed as being in Belgium not China
and they are listed as being in Belgium not China
search for 2sk170 on ebay and some pictures of sale item have polida written, it is not the name of the seller
Space Egg, looks like you have 2sk170.
Check the pinch off voltage.
You need a megohm resistor for this test.
From memory expect the lower Idss to have pinch off near 400 to 500mV and the higher Idss to be around 500mV to 700mV.
http://www.forsselltech.com/media/attachments/JFET_Jig1.pdf
Measure Vgs/Vp (-ve value) when the 18V of the batteries are across the 1M & the jFET.
Instead of an ammeter use 100r and a voltmeter reading to 1.999V for the other tests.
Check the pinch off voltage.
You need a megohm resistor for this test.
From memory expect the lower Idss to have pinch off near 400 to 500mV and the higher Idss to be around 500mV to 700mV.
http://www.forsselltech.com/media/attachments/JFET_Jig1.pdf
Measure Vgs/Vp (-ve value) when the 18V of the batteries are across the 1M & the jFET.
Instead of an ammeter use 100r and a voltmeter reading to 1.999V for the other tests.
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Even SIMPLER ! 🙂
MASantos...
...Joking aside...( Ha Ha ! )
I have been looking at the 'audio testing' possibilitys.
I think my obssesion level will reach about 101% on this project !!!
So...
Was looking at this...
...There's a thread somewhere, called ' JFET Bride Of Zen '...
...Here's a few versions of what they are messing with...
...Transistor-socket...BINGO...drop 'em in...pull 'em out...!...
Good for 'listening' to capacitors, resistors, WIRE !, chewing-gum foil, etc. etc.
Am thinking to make a 'balanced' something-like-this...
...could be interesting...
...a few component sockets...
...get a shunt-reg made first for decent PSU.
BOOM !
Si.
PS...My main concern with the eBay seller mentioned, is that CLEARLY the JFET's I recieved, are from NUMEROUS different batches, possibly 'left overs' from some kind of 'vague factory matching' somewhere.
At least with the 'ammo-belt' theory, you are getting a 'stream' right off the line.
Question...
...How much 'variation' or 'similaritys' or 'spread' do people who have bought 'ammo-strip' get ?
Salas ? Merlin ? Ricardo ?
MASantos...
...Joking aside...( Ha Ha ! )
I have been looking at the 'audio testing' possibilitys.
I think my obssesion level will reach about 101% on this project !!!
So...
Was looking at this...
...There's a thread somewhere, called ' JFET Bride Of Zen '...
...Here's a few versions of what they are messing with...
...Transistor-socket...BINGO...drop 'em in...pull 'em out...!...
Good for 'listening' to capacitors, resistors, WIRE !, chewing-gum foil, etc. etc.
Am thinking to make a 'balanced' something-like-this...
...could be interesting...
...a few component sockets...
...get a shunt-reg made first for decent PSU.
BOOM !
Si.
PS...My main concern with the eBay seller mentioned, is that CLEARLY the JFET's I recieved, are from NUMEROUS different batches, possibly 'left overs' from some kind of 'vague factory matching' somewhere.
At least with the 'ammo-belt' theory, you are getting a 'stream' right off the line.
Question...
...How much 'variation' or 'similaritys' or 'spread' do people who have bought 'ammo-strip' get ?
Salas ? Merlin ? Ricardo ?
Attachments
If my Simplistic goes to a DCB1 what should be the minimum value of the output cap of Simplistic ?
