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!
Last edited:
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..........
/
greenhouse_hum
Member
It has been a busy few months, and I've decided to go simpler, so I thought I'd provide an update.
Instead of cutting individual slots for the 500 series modules I ordered two CAPI 511 racks that are going to slide into the new faceplate frame. As of yesterday, the first one is built and in the hands of the metalworker to get measurements and begin his work. In addition to the two CAPI racks, I have decided to keep the original API meters in the design - and that's all for now!
Attached is the basic photo of the piece. I hope to have it in my possession before the end of the month! I am open to suggestions from you kind folks as to what to use the remaining faceplate space for. The metalworker explained it will be easy to cut into that space at a later date when I decide what to do with it.
Instead of cutting individual slots for the 500 series modules I ordered two CAPI 511 racks that are going to slide into the new faceplate frame. As of yesterday, the first one is built and in the hands of the metalworker to get measurements and begin his work. In addition to the two CAPI racks, I have decided to keep the original API meters in the design - and that's all for now!
Attached is the basic photo of the piece. I hope to have it in my possession before the end of the month! I am open to suggestions from you kind folks as to what to use the remaining faceplate space for. The metalworker explained it will be easy to cut into that space at a later date when I decide what to do with it.
Brian Roth
Well-known member
Belated reply and only SLIGHTLY on topic. I ran across this video and don't know the context relating to Dallas radio stations decades ago.
But, from 0:45 through 1:10 we see a CCA Ultimate in action on the air.
Bri
But, from 0:45 through 1:10 we see a CCA Ultimate in action on the air.
Bri
- Joined
- Apr 14, 2023
- Messages
- 22
I'd like to clear up a couple of misconceptions about older broadcast consoles...
I've refurbished more than a dozen older broadcast mixing consoles for people over the last decade, and maintained many dozens more over my 50+ years as a broadcast engineer. The performance can be much better than you think.
The Shalco ladder type rotary attenuators that Gates/Harris (and most others) used in their consoles were only about 0.5db/step in the critical 2:00 area. Not 2db. The tracking between the stereo channels was usually pretty good on them as well. While it is certainly possible to catch the control at in-between spots, where the two stereo channels would be out of balance, it was just as likely that they would be in sync. The source material was usually responsible for more imbalance problems than those pots. Have you checked the tracking on most carbon stereo pots? Even the Allen Bradly "Mod Pots" left much to be desired. P&G rotary pots were much better, but quite expensive.
The attenuation steps did grow wider btw as the fader was turned down towards max attenuation. Most good engineers tried to keep all the source levels such that the pots were usually running in the 1:00-2:00 area for normal output levels on the board...to minimize any miss-tracking, and make smoother level changes.
The mix busses were usually constant impedance, but it was a fairly low impedance to minimize noise pickup. The mix buss impedance was usually maintained by a combination of the attenuators, and the resistors on the "make before break" on-off switches on the channels. On most consoles these were very high quality switches...although some cheaper consoles like the Gates "Studioette" used telephone type switches, which didn't hold up very well.
Early solid state consoles (like nearly everything else then) used less than great semiconductors, capacitors, resistors etc. That's what was available then. I've substituted modern mic preamps for those program amplifiers with very good results. Especially useful are preamps that have low-gain settings. Usually around 30db of gain is a good working area, depending on the console input levels. I've easily gotten old Gates "snow-plow" consoles like the Gates "Executive" to achieve very flat freq response, and distortion+noise figures down in the 0.05% ranges. In other words, as good or even better than most recent mixing consoles full of dozens of IC's and caps on every input module. Nearly everything is passive in the old consoles. The sound can be very pure and delightful!
One of the design engineers for the "CCA Ultimate" console was a very good friend of mine (Ed Bench). He passed away some years ago, but provided a constant river of knowledge to this (then) young broadcast engineer. I had one of those consoles at KSD-FM in St. Louis for quite a few years in the 2nd Production Studio. I always thought it was a fine sounding piece of gear, and we never had any problems with it. It was later replaced by a Ward Beck console which came out of service in the Air Studio. I'm not sure what ever became of it. I think we donated it to a non-profit station of some sort....and went on serving.
Oh, and btw, the designers at UTC knew every bit as much (or even more) about transformer design than anyone at Jensen. I have open-reel air checks of radio stations with as many as 30 (mostly) UTC transformers in the air chain, and the sound is still very good. Most performance/sound quality issues were the result of something else...weak tubes, bad caps, noisy resistors etc. Not the transformers. You do know that Jensen doesn't make most of their own transformers...right? Not so with UTC (when they were still in business). I'm not dissing Jensen btw, I like a lot of their transformers. But there was nothing wrong with the better UTC transformers either.
Dave O.
I've refurbished more than a dozen older broadcast mixing consoles for people over the last decade, and maintained many dozens more over my 50+ years as a broadcast engineer. The performance can be much better than you think.
The Shalco ladder type rotary attenuators that Gates/Harris (and most others) used in their consoles were only about 0.5db/step in the critical 2:00 area. Not 2db. The tracking between the stereo channels was usually pretty good on them as well. While it is certainly possible to catch the control at in-between spots, where the two stereo channels would be out of balance, it was just as likely that they would be in sync. The source material was usually responsible for more imbalance problems than those pots. Have you checked the tracking on most carbon stereo pots? Even the Allen Bradly "Mod Pots" left much to be desired. P&G rotary pots were much better, but quite expensive.
The attenuation steps did grow wider btw as the fader was turned down towards max attenuation. Most good engineers tried to keep all the source levels such that the pots were usually running in the 1:00-2:00 area for normal output levels on the board...to minimize any miss-tracking, and make smoother level changes.
The mix busses were usually constant impedance, but it was a fairly low impedance to minimize noise pickup. The mix buss impedance was usually maintained by a combination of the attenuators, and the resistors on the "make before break" on-off switches on the channels. On most consoles these were very high quality switches...although some cheaper consoles like the Gates "Studioette" used telephone type switches, which didn't hold up very well.
Early solid state consoles (like nearly everything else then) used less than great semiconductors, capacitors, resistors etc. That's what was available then. I've substituted modern mic preamps for those program amplifiers with very good results. Especially useful are preamps that have low-gain settings. Usually around 30db of gain is a good working area, depending on the console input levels. I've easily gotten old Gates "snow-plow" consoles like the Gates "Executive" to achieve very flat freq response, and distortion+noise figures down in the 0.05% ranges. In other words, as good or even better than most recent mixing consoles full of dozens of IC's and caps on every input module. Nearly everything is passive in the old consoles. The sound can be very pure and delightful!
One of the design engineers for the "CCA Ultimate" console was a very good friend of mine (Ed Bench). He passed away some years ago, but provided a constant river of knowledge to this (then) young broadcast engineer. I had one of those consoles at KSD-FM in St. Louis for quite a few years in the 2nd Production Studio. I always thought it was a fine sounding piece of gear, and we never had any problems with it. It was later replaced by a Ward Beck console which came out of service in the Air Studio. I'm not sure what ever became of it. I think we donated it to a non-profit station of some sort....and went on serving.
Oh, and btw, the designers at UTC knew every bit as much (or even more) about transformer design than anyone at Jensen. I have open-reel air checks of radio stations with as many as 30 (mostly) UTC transformers in the air chain, and the sound is still very good. Most performance/sound quality issues were the result of something else...weak tubes, bad caps, noisy resistors etc. Not the transformers. You do know that Jensen doesn't make most of their own transformers...right? Not so with UTC (when they were still in business). I'm not dissing Jensen btw, I like a lot of their transformers. But there was nothing wrong with the better UTC transformers either.
Dave O.
