1967 Brüel & Kjaer type 2107: Tube Saturated Noise Sweeper by Hideaway Studio published on 2020-09-16T10:08:59Z Awakening yet another late 1960s Brüel & Kjaer type 2107 Frequency Analyser from a decades long slumber for full assessment. These amazing all tube swept regenerative band pass filters are now very elderly and really do need very careful inspection prior to being recapped and modified for studio use. In this case the unit has been slowly powered up to 50% mains voltage in stages on an isolated, current limited, Variac to determine overall condition including the state of the custom main ganged tuning pot assembly which is sadly prone to contact noise in the upper quadrant. They can sometimes be removed, cleaned and rebuilt but thankfully in this case it passed with flying colours so another unit now awaiting full restoration and hopefully an interesting future. As you can hear in the recording, these units will run at 50% but its resulted in some rather nice tube saturation in the process :) In this case the unit is filtering a noise source with the regen control turned in the high position. I have overhauled so many of this era of B&K by now that I can safely say that the chances of sometimes spectacular HT cap failure in these units is just too high to be taking chances and simply plugging them in and hoping for the best. For the tube era units, even if they fire up, it won't ultimately turn out nicely - these remarkable beasts are too precious to be treating that way! Recording Copyright D.A.Wilson, Hideaway Studio, 2020. Genre Bruel & Kjaer