Hi,
just a few remarks/ questions:
you have 20dB of gain (2k2 /22k). This is a bit high for a preamp (even if you want to mate it with an F4)
The value of R5 and R6 can be calculated so the output sits at aproximately 10-11V (half the supply voltage)
The 100k´s could be moved to the gate again
Why use 2sk389 for the current sources?
William
just a few remarks/ questions:
you have 20dB of gain (2k2 /22k). This is a bit high for a preamp (even if you want to mate it with an F4)
The value of R5 and R6 can be calculated so the output sits at aproximately 10-11V (half the supply voltage)
The 100k´s could be moved to the gate again
Why use 2sk389 for the current sources?
William
This is very interesting!
I'm afraid I'm not into electronic design very much so cannot contribute with any comments about the schematics, but I'm thinking about trying to build one.
Which type of LSK389 would be suitable for the schematics posted, type A, B or C?
I hope you can excuse my ignorance.
/Fredrik
I'm afraid I'm not into electronic design very much so cannot contribute with any comments about the schematics, but I'm thinking about trying to build one.
Which type of LSK389 would be suitable for the schematics posted, type A, B or C?
I hope you can excuse my ignorance.
/Fredrik
wuffwaff said:
Hi William,
What would be your suggestion for values R1-R4, If the gain is too high?
I used the LSK389 for the current source I had them already. But you are right a mosfet or something else could be used. If you would like to suggest a better part, I'm open to ideas.
Thank you!
-David
dw8083 said:
ratio 2k2/22k gives you gain
make it 4k7/22k to halve it
for CCSes (both upper and one lower) you can use whatever you want.........but-stay with LSKs if that suits you,or make two BJT CCSes .........as in Babelfish,for instance.
boyz at toob forum are frenzy with LED referenced CCSes ,but I have no any valid link handy in this moment.
anyway- I'll choose CCS a la Babelfish before LSK one ; both- cheaper and better
hehe-and just for fun-when you going to make final version,make shunt regs for both sides
Babowana said:>>O<<
Hey schematic, post#29, forgive me for my question.
How are you going to work with no input coupling cap?
you're dumb almost as Serb ..........
gates are referenced to gnd via 100K resistors
i REALY LOOK AT OTHER THINGS,PRdamn caps lock.....esuming that schematic is almost correct;
this way it will work
R5 and R6 really needs trimming - to achieve 4,7 mA through each half of upper LSK, and this way- as in every proper susy ,output caps are included in fdbck loop........theoretically killing cap induced nasties (if any) through susy effect
Attachments
Babowana said:
Heh . . . ^db^
Hey! Schematic above! Only two questions.
What is going to be your voltage gain? 100/33 < 22K/4.7K
You really going to waste potential thru D1 and D2?
re-read my previous post
100 will not be 100,they mmust be trimed for current of 4,7mA
D1 and D2 are CCSes-where is waste?
I have thought R5 and R6 as too low.
And, -22V minus few voltages will be used across D1 and D2.
How about introducing the input coupling caps and using
only +rail? If so, we could use lower V across D1 and D2,
and could have bigger R5/R6. Then, the voltage gain will
follow the value of 22K/4.7K . . .
Don't take this seriously. Just an opinion ^^.
And, -22V minus few voltages will be used across D1 and D2.
How about introducing the input coupling caps and using
only +rail? If so, we could use lower V across D1 and D2,
and could have bigger R5/R6. Then, the voltage gain will
follow the value of 22K/4.7K . . .
Don't take this seriously. Just an opinion ^^.
Babowana said:I have thought R5 and R6 as too low.
And, -22V minus few voltages will be used across D1 and D2.
How about introducing the input coupling caps and using
only +rail? If so, we could use lower V across D1 and D2,
and could have bigger R5/R6. Then, the voltage gain will
follow the value of 22K/4.7K . . .
Don't take this seriously. Just an opinion ^^.
I have no graphs for LSK and I can't know values of R5 and R6 for 4,7mA without graphs and without LSKs on my bench
they're there as CCSes,so I can't see connection between values of R5 and R6 and overall gain
degeneration resistors in sources of "active" (lower) LSK will have influence on OLG,certainly.
anyway-without graphs I can't tell most adequate voltage for plus and minus PSUs,but I presume that these voltages are good starting point.
you can always choose single sided supply ,as you say-implementing caps on inputs,moving 100K resistors away from gates......
why not-if that's your Zen.........
you know that I don't take seriously anything..........
yeah, I don't think Choky and Bobo ever get to build anything themselves, their too busy helping everyone else out!
(no I didn't expect you to build it choky! Didn't I see you with some Krell clone PCB's?)
If you are going to use this with an Aleph 30, you might take a look at increasing the source resistance to reduce the gain. (I am assuming you are using this with a CD player not vinyl).
The BOSOZ has lower distortion with reduced gain (if you reduce the gain by adding source resistance, that is.) This circuit, I think, is more like an Aleph "J"P -- I am not sure if the aleph P also has lower distortion with more source resistance -- maybe one of the gurus out there can confirm.
Anyway, if your CD player is putting out 2 volts, I think you only need about 6dB of gain (if that) to get full output from the Aleph 30. I may have to dig up my tutorial sheet on dB calculations.
The fact that you have balanced sources is a benefit. I saw some problems with unbalanced to balanced conversion with the BOSOZ. But then, this is not really a BOSOZ.
JJ
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