greenhouse_hum
Member
B = 5.875 inches
C = 4.1875 inches
D = 16.474* degrees
E = 0.1250 inches
? = don’t have yet, need to throw the front faceplate back into the rack to see how it sits in it!
CCA "Ultimate" Console Revival
- Thread starter greenhouse_hum
- Start date
Help Support GroupDIY Audio Forum:
B = 5.875 inches
C = 4.1875 inches
D = 16.474* degrees
E = 0.1250 inches
? = don’t have yet, need to throw the front faceplate back into the rack to see how it sits in it!
greenhouse_hum
Member
I picked up the sharpie and got down to business this evening. Ten individual 500 series units on each side should fit in theory. These standard dimensions are what I was basing my measurments on: API 500 Series Standard Specs
Brian Roth
Well-known member
I see a "woopsie!" with those multiple vertical "metal wisps" between each module. They will be fragile.
Maybe better to go back to the original bucket concept????
I learned about "wisps" when I originally tried to fit two 1.5" wide modules "sideways" into a standard 3.5" tall rack panel. Only a quarter inch metal wisp at the top and bottom, so I used a 3RU panel to ensure "plenty of metal meat". Example:
http://brianroth.com/custom/adm-front2.jpg
Bri
Maybe better to go back to the original bucket concept????
I learned about "wisps" when I originally tried to fit two 1.5" wide modules "sideways" into a standard 3.5" tall rack panel. Only a quarter inch metal wisp at the top and bottom, so I used a 3RU panel to ensure "plenty of metal meat". Example:
http://brianroth.com/custom/adm-front2.jpg
Bri
PermO
Well-known member
Yes, considdering the weight of 10x series 500 unit I think you'll need something more sturdy than just a frontpanel with slots.
This might help a little on what the CCA Ultimate series was...and what that mystery line amp was really for.
Nearly every console of the era (Gates, CCA, RCA, LPB, and a few others), and before, used a passive mixing network designed to be constant impedance regardless of how many channels were on or off, and regardless of fader position. Those attenuators/faders were stepped attenuators that maintained a constant load on the source and provided a constant source impedance to the mixing network. The line inputs were entirely passive (shown as such in the block diagram you posted), with the source device going only through switching and a transformer, primarily because the faders and mixing network were unbalanced, and sources were balanced. The attenuator had a "normal" position of about 2:00, at which point they provided about 10-12dB of attenuation. Since the mixing was passive, it was also very lossy, with the total loss depending on the channel count. The mixing network was then followed by a "booster" amp to make up for the losses, typically 30dB or so, to get everything back to a normal line level of +4dBu or +8dBu (both were studio standards). There wouldn't be a line amp per input channel, there would be a line amp per bus, in this case of two stereo busses, there would have been four, not counting monitor boosters, and cue amps. The thing depended on 600 ohm source impedances that expected 600 ohm loads.
The Altec faders, indeed all stepped faders of the day, were well built to last almost forever, but suffered from two rather serious problems. First, the step size, which was 2dB, sometimes more. That meant that the limited number of steps (30 or so?) would result in 2dB jumps in level, except for the highest attenuation positions near fully CCW, where the last two jumps could be bigger. There was no smooth fading! It was only smooth if it was done quickly. There was no fine adjustment of level, just 2dB steps. The only point was: constant impedance. The other rather fatal flaw (again, all manufacturers faders) was with stereo models. The left and right steps didn't happen simultaneously. Again, if you moved the fader quickly, it was percieved as tracking and smooth, but fine adjustments could result in 2dB channel balance errors. There was a "Cue" detent switch at the full CCW position that placed one or both channels into a cue circuit for setting up tapes and cuing records. Switching a channel off actually removed the fader from the mix network and substitued a resistor (that persistent desire for constant impedance). Channel switching was fairly complex, Program to the right, center off, Audition to the left...times 2 for stereo. That's why the big Switchcraft leaf switches with precisely "timed" switching.
By the mid 1970s, manufactures started to figure out that a continuous fader (non-stepped) was desired, and at about the same time, linear faders were becoming popular. That meant the entire topology had to change. Mixing busses were still passive, but now buffered. Line amps with make-up gain were still required. While the old stepped faders were incredibly reliable, that reliability was slowly traded for smooth wide-range attenuation. And channel tracking was then an even bigger problem, because early faders by Duncan (found in the UREI broadcast boards known as the "Mod One") didn't rack worth a hoot, and actually would alter channel levels if the slider knob was slightly rotated. Improvements in one area, more problems in others. The Duncan faders had a short life span, and would become noisy or just fail at certain points of the travel. We didn't get around those problems until low cost monolithic VCAs appeard (from dbx), and the now legendary Penney and Giles vertical faders appeared. Cost was traded off for reliability and tracking. The most popular broadcast boards of the late 1970s and 1980s were either P&G stereo faders or linear taper faders driving VCAs. Once design by Auditronics had the odd failure mode that when a fader became dirty or intermittent it resulted in the VCA going suddently to full gain. Yikes, that was a bad idea!
I'm not sure of the benefit to repurposing such a beast. Certainly not for the faders. If you add all those 500 modules...well, OK, but that's adding a whole lotta electronics driving 600 ohm loads. Talk about burning up power. The transformers in the line amps add distortion (this was pre-Jensen when transformers got good), but I guess people like distortion these days. Hope you like IMD, 'cuse you'll definitely have it. The lossy summing network will punish you with noise from the extra makeup gain required. Remember, these broadcast boards were designed with much less concern for noise, and more concern for headroom and longevity. The gain structure would offer as much as 25-30dB of headroom post-fade, and the inputs were passive, so it would be hard to clip anything. Jocks could peg the VU meter without any issues other than damaging the meter. The transformers would squish of course. But to do that, you let the noise floor come up. In broadcast it didn't matter because an AM transmitter couldn't do better than 50dB S/N anyway, and FM was only a little better at 68dB. Tape was, of course, tape...pre high output high bias, Scotch 111, so high noise floor too. And carts...no better. The basic audio quality of any of these consoles is, frankly, poor, but so was everything else back then, so what didn't matter then might be more of a concern today. We are, after all, doing (fake) 24 bits, right?
They do have a nice vintage look, though!
Watch out for the monitor muting and "on-air" sign switching on the mic inputs.
Nearly every console of the era (Gates, CCA, RCA, LPB, and a few others), and before, used a passive mixing network designed to be constant impedance regardless of how many channels were on or off, and regardless of fader position. Those attenuators/faders were stepped attenuators that maintained a constant load on the source and provided a constant source impedance to the mixing network. The line inputs were entirely passive (shown as such in the block diagram you posted), with the source device going only through switching and a transformer, primarily because the faders and mixing network were unbalanced, and sources were balanced. The attenuator had a "normal" position of about 2:00, at which point they provided about 10-12dB of attenuation. Since the mixing was passive, it was also very lossy, with the total loss depending on the channel count. The mixing network was then followed by a "booster" amp to make up for the losses, typically 30dB or so, to get everything back to a normal line level of +4dBu or +8dBu (both were studio standards). There wouldn't be a line amp per input channel, there would be a line amp per bus, in this case of two stereo busses, there would have been four, not counting monitor boosters, and cue amps. The thing depended on 600 ohm source impedances that expected 600 ohm loads.
The Altec faders, indeed all stepped faders of the day, were well built to last almost forever, but suffered from two rather serious problems. First, the step size, which was 2dB, sometimes more. That meant that the limited number of steps (30 or so?) would result in 2dB jumps in level, except for the highest attenuation positions near fully CCW, where the last two jumps could be bigger. There was no smooth fading! It was only smooth if it was done quickly. There was no fine adjustment of level, just 2dB steps. The only point was: constant impedance. The other rather fatal flaw (again, all manufacturers faders) was with stereo models. The left and right steps didn't happen simultaneously. Again, if you moved the fader quickly, it was percieved as tracking and smooth, but fine adjustments could result in 2dB channel balance errors. There was a "Cue" detent switch at the full CCW position that placed one or both channels into a cue circuit for setting up tapes and cuing records. Switching a channel off actually removed the fader from the mix network and substitued a resistor (that persistent desire for constant impedance). Channel switching was fairly complex, Program to the right, center off, Audition to the left...times 2 for stereo. That's why the big Switchcraft leaf switches with precisely "timed" switching.
By the mid 1970s, manufactures started to figure out that a continuous fader (non-stepped) was desired, and at about the same time, linear faders were becoming popular. That meant the entire topology had to change. Mixing busses were still passive, but now buffered. Line amps with make-up gain were still required. While the old stepped faders were incredibly reliable, that reliability was slowly traded for smooth wide-range attenuation. And channel tracking was then an even bigger problem, because early faders by Duncan (found in the UREI broadcast boards known as the "Mod One") didn't rack worth a hoot, and actually would alter channel levels if the slider knob was slightly rotated. Improvements in one area, more problems in others. The Duncan faders had a short life span, and would become noisy or just fail at certain points of the travel. We didn't get around those problems until low cost monolithic VCAs appeard (from dbx), and the now legendary Penney and Giles vertical faders appeared. Cost was traded off for reliability and tracking. The most popular broadcast boards of the late 1970s and 1980s were either P&G stereo faders or linear taper faders driving VCAs. Once design by Auditronics had the odd failure mode that when a fader became dirty or intermittent it resulted in the VCA going suddently to full gain. Yikes, that was a bad idea!
I'm not sure of the benefit to repurposing such a beast. Certainly not for the faders. If you add all those 500 modules...well, OK, but that's adding a whole lotta electronics driving 600 ohm loads. Talk about burning up power. The transformers in the line amps add distortion (this was pre-Jensen when transformers got good), but I guess people like distortion these days. Hope you like IMD, 'cuse you'll definitely have it. The lossy summing network will punish you with noise from the extra makeup gain required. Remember, these broadcast boards were designed with much less concern for noise, and more concern for headroom and longevity. The gain structure would offer as much as 25-30dB of headroom post-fade, and the inputs were passive, so it would be hard to clip anything. Jocks could peg the VU meter without any issues other than damaging the meter. The transformers would squish of course. But to do that, you let the noise floor come up. In broadcast it didn't matter because an AM transmitter couldn't do better than 50dB S/N anyway, and FM was only a little better at 68dB. Tape was, of course, tape...pre high output high bias, Scotch 111, so high noise floor too. And carts...no better. The basic audio quality of any of these consoles is, frankly, poor, but so was everything else back then, so what didn't matter then might be more of a concern today. We are, after all, doing (fake) 24 bits, right?
They do have a nice vintage look, though!
Watch out for the monitor muting and "on-air" sign switching on the mic inputs.
Brian Roth
Well-known member
@jaddie Very well described! I "grew up" in a "cusp" era of this biz (beginning in the late 60's for me). Likewise, that CCA from that time was a mixture of new and old, with the Opamp Labs "cans" used for gain requirements along with the Altec stepped attenuators.
Without seeing a full diagram of the CCA, I had wondered if that "Line amp" shown in post #1 in this thread could have been a makeup amp from a passive mix bus. But, a calculated 50 dB gain seemed high to me for a 10 pot mixer.
Bri
Without seeing a full diagram of the CCA, I had wondered if that "Line amp" shown in post #1 in this thread could have been a makeup amp from a passive mix bus. But, a calculated 50 dB gain seemed high to me for a 10 pot mixer.
Bri
MidnightArrakis
Well-known member
WELL!!!.....that little dissertation of yours on vintage broadcast consoles just certainly knocked the wind out of Greenhouse's sail!!!
/
greenhouse_hum
Member
Regarding the weight discussion:
This faceplate metal is pretty darn sturdy. I think if I laser cut to exact slot specs per API, and have screw holes for support, I might not fit as many as ten 500 series modules (as in the proposed sharpie drawing) but I wager it’ll work with 8 and 8. Going to proceed with caution!
Regarding the tech specs of the console in its original iteration:
MA, you underestimate my optimism! This whole project is a learning experience, no wind knocked out my sails just yet. Speaking of, did you see my last post with the updated dimensions? I’m curious what your CAD program tells us!
Jaddie, what a wealth of knowledge - my goodness. I am actually interested in the distortion/saturation provided by UTC output transformers on a mix bus, so I’m hoping to use some era specific parts for that. I already have one UTC-24, so I’m thinking I might a/b it versus the funkenwerk clones. If the clones sound just as good then maybe I’ll flip the UTC since they sell for 400-500 USD on Ebay).
Everything else you mentioned about the overall sound quality, and constraints of the era, makes good sense. With how I’ve gutted the console so far I am only planing on repurposing the console chassis, some of the transformers, the Switchraft switches, and the original VU meters.
This is truly a revamp, as opposed to a revival. Maybe I should rename the thread title…
I hope you continue to follow along, for I might have some questions about some of the parts you mentioned!
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That's perfect! Knocking out wind was never my intention.
I'm not suggesting it, but there could be an entire thread here about distortion, the various types and nonlinear mechanisms, audibility, and subjective desirability of distortion. The very, very short story is: there is no supporting research that shows humans perfer distortion of any kind. There is a lot of subjective opinion only. The most recent research that directly applies is a paper by the folks at Harmon relating to the preference for headphones with the least distortion. Dolby has instroduced a new "zero distortion" process. And developers through time have always targeted ways of lowering distortion. The UTC transformers were, in fact, the impotus for that! A product introduced in the 1970s, the Valley People Trans Amp, was born of the desire to eliminate mic input transformer distortion.
I have no issue with the desire to add distortion to stems and tracks artistically. However, the general application of any form of nonlinearity to a mix flies in the face of actual research into subjective preference, in favor of what is viewed as art.
There. I said it.
Every distortion generator used in the artistic process should at least be a known as to what its actually doing, why, and how to get rid of the effect down the road when the distortion craze inverts.
I actually have a long-time favorite broadcast console too, the industrial design of which I think is exceptional. I'm not going to say what it is, because you guys will snap up the one I want! But electrically, it's horrible, which I know first hand from being asked to design replacement components that were audibly better. To me, it's just a frame for better parts. It's also huge, and I don't have a space for it, but its a dream project. My idea was to replace the stepped faders with linear pots, and wire all the pots and channel switches to an analog to MIDI control interface that would drive a modern digital mixer. Externally, classic. Internally, 32 bit floating point math. Again, just a dream.
And I got this thing for huge VU meters. I have them already, and the knobs...
greenhouse_hum
Member
I was able to get a referral from a friend to a local metal design company. The senior designer at this company has done extensive business with my friend's family in the past, and he was kind enough to meet with me to discuss my ideas for my console.
I brought him all the schematics I have acquired, the original front panel of the CCA, and an API 550A 500 series module.
We decided he is going to hang on to the materials I brought him and make me an entirely new front faceplate out of stronger material than the original. The piece he is creating will be able to house a WHOPPING 26 individual 500 series modules, the original API VU meters, the original monitor/talkback speaker, the original 1/4-inch jacks, and two of the original Altec knobs.
I'll post some mockup schematics soon!
I brought him all the schematics I have acquired, the original front panel of the CCA, and an API 550A 500 series module.
We decided he is going to hang on to the materials I brought him and make me an entirely new front faceplate out of stronger material than the original. The piece he is creating will be able to house a WHOPPING 26 individual 500 series modules, the original API VU meters, the original monitor/talkback speaker, the original 1/4-inch jacks, and two of the original Altec knobs.
I'll post some mockup schematics soon!
MidnightArrakis
Well-known member
>> So.....you won't be needing any of my mechanical design expertise, right??? Oh, well.....
>> You do realize that a "500-Series" module is -- NOT -- actually 1.50" wide, nor is it 5.25" high.....right???
>> Waiting with bated breath!!!
.....Cruisin' on down-the-road.....do-dah.....do-dah..........
/
