Sorry. I'm just amusing myself.
Over the years I've spent far too much time thinking about console paths.
JR
Over the years I've spent far too much time thinking about console paths.
JR
functional enhancements to my console
- Thread starter Rob Flinn
- Start date
Help Support GroupDIY Audio Forum:
Rob Flinn
Well-known member
I now have another possible option. There is a possibility to buy some 600R faders.
The current place I was going to connect the stereo inputs paralleled with the multitrack tape sends. This might mean that eventually I have the tape sends feeding some digi 888's & maybe a 24 track 2" (if I ever finish restoring it) as well as the 600R fader. The line out that feeds the tape inputs is via a 600R transformer.
What's the opinion on on loading the line output with a load that would be less than 600R. I calculated that if the digi 888 (24k i/p Z)& the fader were in parallel the resulting impedance would be 585R, & obviosuly even less than that with the tape deck in parallel too. I'm not sure of the input Z of my telefunken tape deck, but I'm quite sure that it doesn't have transformer balanced i/p's, so should be at least 10k, which would result in 553R.
The line out transformer is driven directly from a MCI 2001 (HA911) op amp. The spec says it will drive +24dB into 600R. Peak o/p current 50mA. I'm suspecting a little close to the mark with the tape deck & the 888 ????
The current place I was going to connect the stereo inputs paralleled with the multitrack tape sends. This might mean that eventually I have the tape sends feeding some digi 888's & maybe a 24 track 2" (if I ever finish restoring it) as well as the 600R fader. The line out that feeds the tape inputs is via a 600R transformer.
What's the opinion on on loading the line output with a load that would be less than 600R. I calculated that if the digi 888 (24k i/p Z)& the fader were in parallel the resulting impedance would be 585R, & obviosuly even less than that with the tape deck in parallel too. I'm not sure of the input Z of my telefunken tape deck, but I'm quite sure that it doesn't have transformer balanced i/p's, so should be at least 10k, which would result in 553R.
The line out transformer is driven directly from a MCI 2001 (HA911) op amp. The spec says it will drive +24dB into 600R. Peak o/p current 50mA. I'm suspecting a little close to the mark with the tape deck & the 888 ????
I am not a fan of 600 phm terminations, especially for short local runs... IMO just more ground and PS currents to worry about, for little (no?) practical benefit.
But that is my personal opinion...
JR
But that is my personal opinion...
JR
Rob Flinn
Well-known member
Thanks John.
The 600R fader is the way it's done on the standard MCI 400. As you say probably not ideal, considering the chip driving it. My console has VCA's automation so avoids the 600R faders.
The 600R fader is the way it's done on the standard MCI 400. As you say probably not ideal, considering the chip driving it. My console has VCA's automation so avoids the 600R faders.
Bill Wilson
Well-known member
- Joined
- Apr 12, 2010
- Messages
- 254
Hi Rob: I ran console checkout at MCI 73-73 when the 416 was being shipped. The reason for the 428 was to get around a patent issue w Dave Harrison on the track assign switching. They changed the paint color & the console number but the internal circuitry was essentialy the same. When the circuitry was originally designed they were still thinking in terms of 600 ohm faders & pots; I modded several 416's w 10k faders this took the load off the harris 911 opamps & reduced loading distortion.
They even used 600 ohm pots in the monitor module for quad & stereo monitor controls, they were later changed to 1.5k rotaries to clean up distortion in the control room monitor sends. The 600 ohm transmission busses etc. were a carry over from boards for broadcast facilities.
They even used 600 ohm pots in the monitor module for quad & stereo monitor controls, they were later changed to 1.5k rotaries to clean up distortion in the control room monitor sends. The 600 ohm transmission busses etc. were a carry over from boards for broadcast facilities.
Rob Flinn
Well-known member
Hi Bill.
My 428b is a little different, in that the B has transistor pairs after 3 of the op amps on the channels to beef the signal up. Unfortunately where it drive the fader normally this is not the case. However because my board also has the vca automation fitted VCA's replace the 600R fader.
ANyway i think I'm going to avoid using 600R faders for my subgroup panel on yours & John advice. Thanks for you tip !
My 428b is a little different, in that the B has transistor pairs after 3 of the op amps on the channels to beef the signal up. Unfortunately where it drive the fader normally this is not the case. However because my board also has the vca automation fitted VCA's replace the 600R fader.
ANyway i think I'm going to avoid using 600R faders for my subgroup panel on yours & John advice. Thanks for you tip !
