tubehunter
21-01-2014, 15:02
Here is a very nice digital pre amplifier in a quality aluminium case.
There are three pairs of RCA Phono inputs and one pair of outputs.
Controlled by either the small remote or the knob on the case, your settings can be saved for next start up.
I have slightly modded this by changing the power supply smoothing caps for quality Elna cerafines and added small film caps close to the chip pins as recommended by Texas Insr'.
The 10k ohm resistors which were in parallel with the chip have been discarded as the chip already has a 10k ohm loading on the source input(I see no need to load it further). Also the 220ohm resistors in series on the input have been removed as they would just add noise.
The amp is DC coupled through out, no capacitors in the signal path or resistors for that matter.
Good quality R-core transformer is used.
Sounds very good.
This uses the excellent PGA2311 volume control chip from Burr Brown.
Just check out these specs: http://www.ti.com/lit/ds/symlink/pga2311.pdf
£85 inclusive of p&p
Duncan
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6771_zps36daaf70.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6771_zps36daaf70.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6770_zps3dd0bc04.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6770_zps3dd0bc04.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_0274_zps6ba6c93a.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_0274_zps6ba6c93a.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6769_zpsbdb45718.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6769_zpsbdb45718.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6768_zps948760be.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6768_zps948760be.jpg.html)
There are three pairs of RCA Phono inputs and one pair of outputs.
Controlled by either the small remote or the knob on the case, your settings can be saved for next start up.
I have slightly modded this by changing the power supply smoothing caps for quality Elna cerafines and added small film caps close to the chip pins as recommended by Texas Insr'.
The 10k ohm resistors which were in parallel with the chip have been discarded as the chip already has a 10k ohm loading on the source input(I see no need to load it further). Also the 220ohm resistors in series on the input have been removed as they would just add noise.
The amp is DC coupled through out, no capacitors in the signal path or resistors for that matter.
Good quality R-core transformer is used.
Sounds very good.
This uses the excellent PGA2311 volume control chip from Burr Brown.
Just check out these specs: http://www.ti.com/lit/ds/symlink/pga2311.pdf
£85 inclusive of p&p
Duncan
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6771_zps36daaf70.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6771_zps36daaf70.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6770_zps3dd0bc04.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6770_zps3dd0bc04.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_0274_zps6ba6c93a.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_0274_zps6ba6c93a.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6769_zpsbdb45718.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6769_zpsbdb45718.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/preamp/IMG_6768_zps948760be.jpg (http://s514.photobucket.com/user/halx00/media/preamp/IMG_6768_zps948760be.jpg.html)