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The idea of this project was to copy the sound of the 169 mic pre as accurately a possible. A friend of mine bought two original channels from Ebay and I repaired them for him. It was so time consuming that I decided to built new ones when he needed some more. That was much cheaper alternative too.
In blind tests my friend or his colleagues couln't hear difference between the original and clone. In the test setup the output of the original channel was taken directly after the mic pre and buffered like in the clone.
All parts, except the transformer, are available from every electronics store, but finding the transformer is not as difficult as you may think. Neutrik NTM4 is exactly the same transformer as the original Studer 1.022.400.00. Neutrik has a global distribution network, so their products are available almost everywhere.
http://www.neutrik.com/fl/en/audio/210_205801/NTM4_detail.aspx
I redesigned the gain setting which originally had three steps of 13-14 dB. I changed it to four 10 dB steps. A balanced output stage was also added.
There was some extra space on PCB as well as unused switch sections, so I included LED indicators in the gain and filter switches (see the picture). Personally I don't like that kind of "decoration" but I know that some people do. Leave them out if you don't like them.
The rotary switch on the left is common for phase and phantom to save space.
My original version was made using 30 years old Feme switches that I got for free ( http://www.4most.co.uk/assets/Image/swt_04.jpg ). Since the Femes are no longer manufactured, I made another layout for Lorlin switches (to make this project available to the forum members).
As usual, I don't sell anything related to this project. If someone wants to manufacture boards or offer kits, no problem (but the price must be fair). All the information is provided "as is".
DOCUMENTS:
Schematic
https://docs.google.com/open?id=0B_XBYPfmG8pVWkFtYXhNNDZhb0k
Component designations
https://docs.google.com/open?id=0B_XBYPfmG8pVeGJqYU5qTEZkZTA
Components values
https://docs.google.com/open?id=0B_XBYPfmG8pVRmNoQzlfaHZ5eG8
Copper layer (for home etchers)
https://docs.google.com/open?id=0B_XBYPfmG8pVOXM2VE9mMGt2UUk
My other projects:
Neumann W492 EQ
http://www.groupdiy.com/index.php?topic=28332.0
Neumann OA10 discrete op-amp
http://www.groupdiy.com/index.php?topic=34105.0
Studer 169 EQ
http://www.groupdiy.com/index.php?topic=33996.0
Studer 169 EQ in API 500 format
http://www.groupdiy.com/index.php?topic=36522.0
Balanced 12 input summing amplifier
http://www.groupdiy.com/index.php?topic=29082.0
Balancing/unbalancing amplifier
http://www.groupdiy.com/index.php?topic=29333.0
The idea of this project was to copy the sound of the 169 mic pre as accurately a possible. A friend of mine bought two original channels from Ebay and I repaired them for him. It was so time consuming that I decided to built new ones when he needed some more. That was much cheaper alternative too.
In blind tests my friend or his colleagues couln't hear difference between the original and clone. In the test setup the output of the original channel was taken directly after the mic pre and buffered like in the clone.
All parts, except the transformer, are available from every electronics store, but finding the transformer is not as difficult as you may think. Neutrik NTM4 is exactly the same transformer as the original Studer 1.022.400.00. Neutrik has a global distribution network, so their products are available almost everywhere.
http://www.neutrik.com/fl/en/audio/210_205801/NTM4_detail.aspx
I redesigned the gain setting which originally had three steps of 13-14 dB. I changed it to four 10 dB steps. A balanced output stage was also added.
There was some extra space on PCB as well as unused switch sections, so I included LED indicators in the gain and filter switches (see the picture). Personally I don't like that kind of "decoration" but I know that some people do. Leave them out if you don't like them.
The rotary switch on the left is common for phase and phantom to save space.
My original version was made using 30 years old Feme switches that I got for free ( http://www.4most.co.uk/assets/Image/swt_04.jpg ). Since the Femes are no longer manufactured, I made another layout for Lorlin switches (to make this project available to the forum members).
As usual, I don't sell anything related to this project. If someone wants to manufacture boards or offer kits, no problem (but the price must be fair). All the information is provided "as is".
DOCUMENTS:
Schematic
https://docs.google.com/open?id=0B_XBYPfmG8pVWkFtYXhNNDZhb0k
Component designations
https://docs.google.com/open?id=0B_XBYPfmG8pVeGJqYU5qTEZkZTA
Components values
https://docs.google.com/open?id=0B_XBYPfmG8pVRmNoQzlfaHZ5eG8
Copper layer (for home etchers)
https://docs.google.com/open?id=0B_XBYPfmG8pVOXM2VE9mMGt2UUk
My other projects:
Neumann W492 EQ
http://www.groupdiy.com/index.php?topic=28332.0
Neumann OA10 discrete op-amp
http://www.groupdiy.com/index.php?topic=34105.0
Studer 169 EQ
http://www.groupdiy.com/index.php?topic=33996.0
Studer 169 EQ in API 500 format
http://www.groupdiy.com/index.php?topic=36522.0
Balanced 12 input summing amplifier
http://www.groupdiy.com/index.php?topic=29082.0
Balancing/unbalancing amplifier
http://www.groupdiy.com/index.php?topic=29333.0