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Old 24th July 2012, 07:09 PM   #21
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Join Date: Jul 2011
I did excatctly like this .

I used only 2 transistors , BC550c NPN and BC556 PNP
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Old 25th July 2012, 07:58 AM   #22
Mooly is offline Mooly  United Kingdom
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So using the values you have we get the following...

Look how the 0.47uf cap limits the low frequency response and how raising it extends the response. An electroylitic is fine here (watch polarity).

Also see how the response of the amplifier falls at high frequecies. With the higher gain the 100pf cap is limiting the bandwidth. Look at the difference between 100pf and 22pf.

Five screenshots showing this,

1) Output Max. Your amp as it stands into 100k
2) Response. Your amp.
3) Response larger value C1 shows extended LF response.
4) 50Khz squarewave. Your amp as it stands.
5) Lower value of C2. Extends the HF response.
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File Type: png Output Max.PNG (127.2 KB, 112 views)
File Type: png Response.PNG (123.5 KB, 103 views)
File Type: png Response larger C1.PNG (122.5 KB, 96 views)
File Type: png 50Khz Squarewave.PNG (126.4 KB, 95 views)
File Type: png Lower value C2.PNG (126.0 KB, 50 views)
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Old 25th July 2012, 08:08 AM   #23
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thanks mooly , i will do that ,
I will put 4.7uf instead of 0.47
and 22P instead of 100p
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Old 25th July 2012, 09:09 AM   #24
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hi, have look at Minimalist Discrete Hi-Fi Preamp , note the supply, rgds, sreten.
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Old 25th July 2012, 11:11 AM   #25
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Thanks look very interesting maybe I will build it some day
For now I will stay with the radford design
Have a nice day
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