We have been doing some organizing around here lately, and in the process I came across a pair of Mikey's BCP-16 GC NI nickel grid chokes, mounted to an old prototype chassis. I wanted to use them in my system somewhere and the only possible location was in my pair of SR45 tweeter amps, since the mids and woofers use 4 amps per channel. During some discussion it was suggested that there might not be much improvement had by replacing the grid resistor in the tweeter amp with the grid choke because most of the comments we see about grid chokes talk about bass improvement. My experience with grid chokes has been that there is an overall improvement in dynamic punch and liveliness, so I forged ahead and asked Shawn to install the chokes along with upgrading the existing Solen coupling cap to a Russian Teflon cap.
I guessed right. The system treble sounded good before. But the clarity, dynamic snap, and the levels at which we can now play the system without strain in the treble are greatly increased. This is a very worthwhile upgrade. The two holes that sit between the tube sockets normally mount some cathode resistors on a Paramount kit, which uses this same chassis. Some work with a rat tail file will lengthen the holes to fit the choke mounting holes and the BPC-16 will just squeeze in between the T strip next to the 45 socket and the SRC4S board on over the 6CM7 socket. One might be concerned about the possibility of hum pickup. In my application the output of the amp is cutoff by the use of a very small (.016uF) parafeed cap, which works in conjunction with an active crossover to give a steep slope on the RAAL ribbons. So if I was picking up hum, it wasn't getting out to the tweeters, and I can't say for sure if you would experience hum or not if you try this on a full range setup.
I should mention that I have also removed the cathode bypass resistor on the 45 since I am not looking for great bass or gobs of gain, and that we also upgraded the 1.3K sandcast cathode resistor to a pair of 680 ohm 6.5W Dale wirewounds.
I guessed right. The system treble sounded good before. But the clarity, dynamic snap, and the levels at which we can now play the system without strain in the treble are greatly increased. This is a very worthwhile upgrade. The two holes that sit between the tube sockets normally mount some cathode resistors on a Paramount kit, which uses this same chassis. Some work with a rat tail file will lengthen the holes to fit the choke mounting holes and the BPC-16 will just squeeze in between the T strip next to the 45 socket and the SRC4S board on over the 6CM7 socket. One might be concerned about the possibility of hum pickup. In my application the output of the amp is cutoff by the use of a very small (.016uF) parafeed cap, which works in conjunction with an active crossover to give a steep slope on the RAAL ribbons. So if I was picking up hum, it wasn't getting out to the tweeters, and I can't say for sure if you would experience hum or not if you try this on a full range setup.
I should mention that I have also removed the cathode bypass resistor on the 45 since I am not looking for great bass or gobs of gain, and that we also upgraded the 1.3K sandcast cathode resistor to a pair of 680 ohm 6.5W Dale wirewounds.
