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Old 24th September 2012, 07:56 PM   #1151
tinitus is offline tinitus  Europe
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found another similar one by R.G.Keen, calling it jfet buffer

thanks Zen mod, but it doenst work
I better wait with this until I got my PC fixed

and yet another one calling it direct coupled jfet/bjt buffer, and 'common textbook curcuit'
I think its originally a bjt curcuit
the jfet is only 'adopted' to give hi-z input

my idea was to place a att/pot between the simple se jfet boz, and this buffer
as I see it, the reason here to use the relatively high gain jfet boz is if having source with too low signal
and thus it makes less sense to place the att/pot in front of it, lowering the input signal even more
seems to me it would make more sense to try and control the high output gain
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Old 24th September 2012, 08:43 PM   #1152
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there is no need to reinvent the wheel

there are numerous guitar/bass preamps around , certainly on DiyA too ;

point is that they're already optimized and we don't need to do that from scratch

especially if you aren't able to post links or pictures , in this moment , to help us visualize what you are thinking
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Old 24th September 2012, 09:34 PM   #1153
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Quote:
Originally Posted by tinitus View Post
sorry, my mouse is broken...
Kudos to your cat !
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Old 24th September 2012, 09:35 PM   #1154
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point is that they're already optimized and we don't need to do that from scratch
then tell me why this se jfet pre I built with components pulled out of 30 year old radios outperforms all my commercial units
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Old 24th September 2012, 10:24 PM   #1155
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I meant on Jfet based preamps , made by ppl who knows what , where, how ..... not commercial drek ditto from text books
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Old 25th September 2012, 07:21 AM   #1156
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Could it be something like this (cascoded SE buffer)?
CCS (here Q3 & Q4) can be executed in many different ways.
hey, thats a real cool looking buffer
I have those BC547

looks like it could be a good mate to the se boz (on symmetric power supply)
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Old 25th September 2012, 11:36 AM   #1157
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...looks like it could be a good mate to the se boz (on symmetric power supply)
We'll talk about it when you repair your mouse, with sch. and all...
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Old 25th September 2012, 02:26 PM   #1158
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sounds great, thanks
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Old 25th September 2012, 04:26 PM   #1159
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for me personally, series resistors are out, sorry
I have to take that back, sorry (again)

done 'correctly' a series resistor seem to work ok
in my case it means placing it right after the first smoothing cap
and bleeder res/LED is placed there too, on the first cap
this way it also 'isolates' the res/LED better from draining the caps closer to the amp curcuit
sounds like I got a little more 'sweetness' this way
and just by a small change in how things are connected
and also amazing that the thing still works after me poking around with a monster solder iron about a hundred times now
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Old 29th September 2012, 05:20 PM   #1160
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Has anyone tried a Salas low voltage shunt reg with this? Where can one find the V rated Jfets?
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