stickjam
Well-known member
I've got a Hammond X5/Leslie 770 that I've gone through the "sell or keep" debate for probably the twentieth time in the nearly last three decades I've owned it. I'm pretty much resigned that I'll never have the guts to let it go since I've owned a Hammond since I was seven years old. I'm also resigned to the fact that I can't logistically get a B3 (it'll never navigate through the studio airlock) So, I've decided to make the best of what I have. BTW, I've got the service manuals around here--I just need to find them! :roll:
There are two objections I have to this setup.. One is noise--it's always had somewhat of a hum emanating from the Leslie--fine for live use but nasty for recording. (The direct out from the console itself is clean, BTW.) My thinking is that this is due to the 770's unbalanced input signal (unlike the 122's balanced input) riding alongside the 110VAC power running through the cable.
My other dislike is that it's too darn sterile-sounding, being digital/solid state. The first thought was to get some tube stage in there to provide some warmth and overdrivability. I considered an effects-loop solution in the console, but I still have the hum issue. So, what do you folks think about any of my latest ideas to give this beast some character?...
1. Install a DI transformer/XLR output on the console. Remove the SS crossover and amps from the 770 Leslie and replace with a DIY version of the amp/crossover used in the Leslie 122 fed from a new XLR input. :?: What kind of iron would be best for the 6550 outputs, as well as the DI to balance/match the organ to 122 levels? Would the existing speaker and horn drivers be compatible? Will a tube-based Leslie provide enough of that "drive" or do I need to continue the glass into the preamp stages too?
2. I once owned a Voce V3 module and was amazed how much the emulation was assisted by its "Generator Leakage" parameter--basically putting a little bit of every harmonic the generator created into every note. Critically listening to my X-5, I realized although it had a nice "keyclick" transient, it had absolutely none of that leakage. I did some fairly-successful experimenting a while back to see if I could add an adjustable generator leakage control to modify the amount of "age and neglect" of the sound. The X-5 has a board that essentially forms a digital equivalent of a tonewheel generator. It consists of one oscillator and a top-octave divider chip feeding 11 series of divide-by-two flip-flops to generate each successive harmonic one octave down; each those go into individual LPFs before they're fed off into the 10-contact keyboard. My idea is to install a ladder of resistors of sufficiently-high value so as to place a negligible impedance difference on the generator outputs. Every output would have a resistor leg tied to it, with the other legs of all the resistors tied into a single buss. Then I'd wire a pot from that buss to signal ground. At minimum (wiper grounded) position, the sound should be clean. Turning the pot toward the other end should introduce increasing amounts of crosstalk between the generator outputs to get that aged and abused organ vibe. :?: Does this sound like it would produce the result I'm looking for? Might there be a simpler solution (read, lower part count) to accomplish the same end?
Thanks
--Bob
There are two objections I have to this setup.. One is noise--it's always had somewhat of a hum emanating from the Leslie--fine for live use but nasty for recording. (The direct out from the console itself is clean, BTW.) My thinking is that this is due to the 770's unbalanced input signal (unlike the 122's balanced input) riding alongside the 110VAC power running through the cable.
My other dislike is that it's too darn sterile-sounding, being digital/solid state. The first thought was to get some tube stage in there to provide some warmth and overdrivability. I considered an effects-loop solution in the console, but I still have the hum issue. So, what do you folks think about any of my latest ideas to give this beast some character?...
1. Install a DI transformer/XLR output on the console. Remove the SS crossover and amps from the 770 Leslie and replace with a DIY version of the amp/crossover used in the Leslie 122 fed from a new XLR input. :?: What kind of iron would be best for the 6550 outputs, as well as the DI to balance/match the organ to 122 levels? Would the existing speaker and horn drivers be compatible? Will a tube-based Leslie provide enough of that "drive" or do I need to continue the glass into the preamp stages too?
2. I once owned a Voce V3 module and was amazed how much the emulation was assisted by its "Generator Leakage" parameter--basically putting a little bit of every harmonic the generator created into every note. Critically listening to my X-5, I realized although it had a nice "keyclick" transient, it had absolutely none of that leakage. I did some fairly-successful experimenting a while back to see if I could add an adjustable generator leakage control to modify the amount of "age and neglect" of the sound. The X-5 has a board that essentially forms a digital equivalent of a tonewheel generator. It consists of one oscillator and a top-octave divider chip feeding 11 series of divide-by-two flip-flops to generate each successive harmonic one octave down; each those go into individual LPFs before they're fed off into the 10-contact keyboard. My idea is to install a ladder of resistors of sufficiently-high value so as to place a negligible impedance difference on the generator outputs. Every output would have a resistor leg tied to it, with the other legs of all the resistors tied into a single buss. Then I'd wire a pot from that buss to signal ground. At minimum (wiper grounded) position, the sound should be clean. Turning the pot toward the other end should introduce increasing amounts of crosstalk between the generator outputs to get that aged and abused organ vibe. :?: Does this sound like it would produce the result I'm looking for? Might there be a simpler solution (read, lower part count) to accomplish the same end?
Thanks
--Bob
