LSK pre - BAF 2013

S

sergiog

Member
Joined 2013
Hi, Juma just finished assembling the post.67 chematic preamp V+/V- 33.5 vdc, Offset OK, added 220R resistor to R4-R5 now I kindly ask you how I can increase the gain (resistor value to be changed) since to hear the music at a decent level I have to turn the knob to about 1/2 volume
pot is Alps Black 50K.Best regards Sergio Italy
 
juma

juma

Member
Joined 2005
Lowering the R6 will increase the gain and the distortion too.
Increasing the R9 will increase the gain also but it it will increase the output impedance (Zout) too.
Zout is determined by value of R9 and it is already very high (6k8 paralleled with Zin of the next stage).
I don't know what is your next stage (amplifier? , pot?) and what is its Zin, but it's possible that you don't lack gain - it might be that your next stage "eats" the gain (low Zin) so you actually might need a buffer rather than more gain in the preamp.
Since you are hiding data about your exact configuration it's hard to help you.
 
william2001

william2001

Member
Joined 2001
Paid Member
Nothing wrong with running a VC at halfway. Sound quality overall is probably better (resolution, detail) with a pot @50% as opposed to 15-20% where you are just throwing away excess signal in the form of heat through a resistive voltage divider.
 
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juma

juma

Member
Joined 2005

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marconi118

Member
Joined 2008
just for my understanding what are the advantage of feeding the signal to the bjts by the emitter kind of cascade instead of feeding it at the basis?
 
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