CCA "Ultimate" Console Revival

[greenhouse_hum]

Hello DIY Friends,

I recently came across an old CCA Ultimate 10 Stereo Console from the 1970s that was left for dead as radio technology went digital. The console chassis, and most internal components, are in fine condition – so I’ve decided to make a project of it. My dream is to combine some of the original engineering concepts, with some added modern designs and functions using the original chassis, to create a custom 10-channel summing mixer.

I have the entire manual for this console (block diagrams, schematics, parts lists, etc). In the coming months I hope to upload all of that information for posterity, and in the process pick your collective brains on how to bring this little gem back to life in 2024 – 54 years after it was pressed into service.

The first schematic I am uploading today, and pinning to this initial post, is the original Line Amplifier for this unit. I’m gathering it only works for a mono source, not stereo, and has a UTC A11 in line as the input transformer, an Op Amp Labs 425, and finally a Altec 15356 as the output transformer.

Do you folks have any suggestions on how to improve this design, or should I leave it alone?

I believe I will need 10 of these line amp channels – each tied to an XLR input – that when in service will feed rotary potentiometers that’ll account for volume adjustments, as well as pan pots for stereo imaging. The original console had Altec pots and no pan function, but I guess that’ll be post #2 after I get a handle on what to do with this line amp section.

Thank you in advance for your time in reading this post, and talent in the form of any ideas you may provide for discussion. I am excited to share this process with all of you!

 

[greenhouse_hum]

Hello Again DIY Friends,

Attached to this post is the simplified block diagram for the CCA console!

Lots of ideas are flying around my head at present, and I think instead of trying to recreate the original input stages I may create my own and then repurpose some of the older transformers and components in the master output section; my idea being I can have a cleaner, more modern, signal coming in and the old school coloration on the way out.

Also, another reason for possibly going in this direction relates to the line amp schematic I posted yesterday. I’m realizing it is going to be difficult to source parts if I want to attempt to create 10 channels of line amps that mirror that original design. The UTC A-11 transformers go for good money online nowadays and are scarce, as do the Altec Transformers. The only reasonably priced component in that diagram is the OpAmp Labs 425 which I can still get new from their website for around $40 USD.

Stay tuned, and as always, I appreciate you following along.

 

[greenhouse_hum]

While researching possible alternatives to the current input channel configuration on this CCA console I keep coming across recommendations for either API 312 style or Neve BA283 style amplifiers. Both can accommodate mic/line, and both are highly regarded. Additionally, they both date back to the 70s - the same design era as the CCA.

I dug further on the Neve, because I envision the master bus section of this project console having API style op amps paired with UTC input and output transformers. Simply, I thought it might be cool to have a Neve tone on the individual channels then sum to the more punchy, American, transformers and DOAs.

Lo and behold, Peterson from DIYRE is in the late stages of designing a Neve style, 73p mic/line pre for the 500 series format: DIYRE 73p

I’m going to get in touch with him to get his input, but I am leaning towards getting ten of those PCB boards, and part kits, as the foundation for my input channels.

We’ll see if I hear back from him!

 

[Brian Roth]

When I was in High School 50+ years ago, I worked at a FM station with one of those. I don't recall much about it <g>.

How many of those "line amps" are in the console? The gain seems somewhat low for a mic input.....but maybe not.

In the block diagram, the actual line inputs are passive.

Bri

 

[abbey road d enfer]

This "line" amplifier has about 30dB gain, so it's definitely NOT a line amplifier as we have come to know them.
It's typical of the period designs, where piling up amplifiers was the norm for high-gain requirements.
30dB is about right for a recording console - I find myself quite often dialing about 30/40dB gain.
But for a radio console, it's not enough, for normal speech level with low output dynamic mics.
It was quite frequent at the time to cascade two such amplifiers with an adjustable attenuator in-between.
Perhaps there are more info in the documents. A level diagram would help understanding.

Edit: I made two mistakes, Brian Roth got it right, the gain is about 50dB, which would not make it produce a true line level (about 0dBu) from an SM7 or RE20 with a person speaking at conversational level. It all depends on the internal operating level. It is quite possible that they had chosen a lower operating level, in order to permit higher headroom.

 

[Brian Roth]

In case folks are wondering what the CCA Ultimate was, I could only find a few pix examples.

https://www.oldradio.com/archives/hardware/CCA-Ultimate.jpg

https://worldradiohistory.com/hd2/I...BC-IDX/69-OCR/1969-12-22-BC-OCR-Page-0012.pdf

Bri

 

[Brian Roth]

Back to that "line amp". Now I do believe it was an actual mic pre. Checking for info on the iron we have this:

1. UTC A11 Input

https://rvb-img.reverb.com/image/up...,t_large/v1557950713/sctcgzcdz5vdc4ukbsab.jpg

2. Altec 15356 output

https://rvb-img.reverb.com/image/up...,t_large/v1678747027/ogbecx2hafafwe4o6ubh.jpg

Back of the napkin calculations.

1, A11 wired 500:50K 20 dB "gain"
2. Opamp Labs 425 stage 24 dB gain
3. Altec 15356 wired 150:600 6 dB "gain'

So, 50 dB (but check my math...lol!) If used as a summing amp, that would suggest a HUGE amount of makeup gain for a 10 channel mixer.

Bri



Bri

 

[abbey road d enfer]

Correct. I neglected the step up output and for some reason miscalculated the opamp gain.

 

[greenhouse_hum]

This "line" amplifier has about 30dB gain, so it's definitely NOT a line amplifier as we have come to know them.
It's typical of the period designs, where piling up amplifiers was the norm for high-gain requirements.
30dB is about right for a recording console - I find myself quite often dialing about 30/40dB gain.
But for a radio console, it's not enough, for normal speech level with low output dynamic mics.
It was quite frequent at the time to cascade two such amplifiers with an adjustable attenuator in-between.
Perhaps there are more info in the documents. A level diagram would help understanding.

Abbey RD,

I plan on uploading more documents in the coming days, and will look for a level diagram. I believe the Altec rotary attenuators on this beast are "Type: 8201-01GG / Z: 600-600" and I am particularly excited to see how they sound once cleaned and confirmed functionality.

Back to that "line amp". Now I do believe it was an actual mic pre. Checking for info on the iron we have this:

1. UTC A11 Input

https://rvb-img.reverb.com/image/up...,t_large/v1557950713/sctcgzcdz5vdc4ukbsab.jpg

2. Altec 15356 output

https://rvb-img.reverb.com/image/up...,t_large/v1678747027/ogbecx2hafafwe4o6ubh.jpg

Back of the napkin calculations.

1, A11 wired 500:50K 20 dB "gain"
2. Opamp Labs 425 stage 24 dB gain
3. Altec 15356 wired 150:600 6 dB "gain'

So, 50 dB (but check my math...lol!) If used as a summing amp, that would suggest a HUGE amount of makeup gain for a 10 channel mixer.

Bri



Bri

Bri,

So are you suggesting that would be too much drive? My hope is to figure out my individual channel configuration, build and ensure those sound good, then direct my attention to the summing portion of the piece; I thought it would be neat to use something similar to the schematics of a component that is already in the original unit, that's why I was looking at that specific line amp, but I am open to any and all suggestions!

 

[greenhouse_hum]

I had some fun sanding the original console front panel. There was so much goop underneath the button and switch faceplates that I decided it deserved a facelift. I plan on painting at a later date, but even seeing the exposed metal looks pretty neat.

 

[PermO]

I like these ideas, this could become something really sweet...

Cheers !

 

[Brian Roth]

@greenhouse_hum .....that "line amp" is not suitable for a line level input signal (despite of the name of the module).

Since you've stripped it down to bare metal, I guess you'll be starting totally from scratch? You'll have an interesting road ahead! <g>

Bri

 

[Brian Roth]

I'm somewhat intrigued about this project, partially because of nostalgia <G!>.

I attached an old Altec catalog sheet re. attenuators. Scrolling down to PDF page 5, we see that CCA used a 20 step, 2 dB per step unbalanced ladder attenuator.

Looking at the simplified block diagram posted in this thread, three of the attenuators are mono, the remaining seven are stereo. And, all stereo and one mono attenuators would have an additional detent "step" at full CCW for "cue".. The pots for the two mic channels won't have the cue detent.

 

[greenhouse_hum]

@greenhouse_hum .....that "line amp" is not suitable for a line level input signal (despite of the name of the module).

Since you've stripped it down to bare metal, I guess you'll be starting totally from scratch? You'll have an interesting road ahead! <g>

Bri

Meaning it has too little gain to amplify a line level source, or too much? I just want to make sure I’m following you!

I'm somewhat intrigued about this project, partially because of nostalgia <G!>.

I attached an old Altec catalog sheet re. attenuators. Scrolling down to PDF page 5, we see that CCA used a 20 step, 2 dB per step unbalanced ladder attenuator.

Looking at the simplified block diagram posted in this thread, three of the attenuators are mono, the remaining seven are stereo. And, all stereo and one mono attenuators would have an additional detent "step" at full CCW for "cue".. The pots for the two mic channels won't have the cue detent.

I’m pleased to hear you’re intrigued, I’ll try my best to keep you hooked!

You’re on the money regarding those faders, here is a photo of one of the stereo Altecs. They seem quite well built.

 

[Brian Roth]

@greenhouse_hum That "line amp" has WAAAY too much gain for a line input. 50 dB gain falls into the mic preamp realm. Looking at the simplified block, CCA ran line inputs through some selector switching circuits, then a line input transformer. That then fed the Altec attenuator; the signal next went through some more switching before hitting the mix bus. Hence the line inputs were passive....no electronics besides switches, transformer and the attenuator.

Yeah, the guts of that Altec are a thing of beauty! Just keep in mind that they adjust the audio level in discrete 2 dB steps, which may or may not be a workflow issue for a summing mixer as you are planning.

Thinking back, those steps were obvious to me when I (low man on the totem pole) worked the Sunday morning shift at the radio station. Besides rolling tapes from preachers, etc. who bought airtime in that daypart, we had a live feed from a local church. The audio came in via a dedicated/"conditioned" phone line, and each Sunday a Bell tech would call me from the church on the CR Hotline. He'd send tones while I'd read back what I was seeing on the CCA VU meters (with that console channel in "Audition"). He sent various frequencies, I'd tell him VU readings, and he would tweak EQ on his end. I had to find the most ideal step on the CCA pot to clearly read the incoming tone levels and then LEAVE IT ALONE <g> as the Bell tech sent me tones.

Likely a Pultec there at the church in 1972! lol

Bri


Bri

 

[MidnightArrakis]

The audio came in via a dedicated/"conditioned" phone line, and each Sunday a Bell tech would call me from the church on the CR Hotline. He'd send tones while I'd read back what I was seeing on the CCA VU meters (with that console channel in "Audition").

[each Sunday a Bell tech would call me from the church on the CR Hotline. He'd send tones while I'd read back what I was seeing on the CCA VU meters] -- I just know that THAT had to be a whole lot of "fun" for you to do with you then being a "young audio dude" back then!!! Right??? I had some similar experiences when I was setting up the stereo audio feeds from a backstage mixing console for "LIVE" concerts going to a local rock FM-station that was going to simulcast the show. Doing that kind of "stuff" made me feel "important", as I knew that tens-of-thousands of radio listeners would be tuning into the station to listen to the concert and I thought it was "SO COOL" that I was a part of the audio-chain that made it all happen. >> AND, NOW!!!......PLEASE WELCOME..........

/

 

[Brian Roth]

@MidnightArrakis That small FM station was an interesting place to work for a young "tech nerd". We had an Associated Press teletype machine (enclosed in a "sound proof" ... kinda... housing). Several clocks were fed with "timing" from....Western Union? We had that dedicated Bell line for various remote purposes. A Marti "Remote pickup" transmitter/receiver RF system ("We're live today from the Grand Opening at Waldo's Shoe Store"). The owner had a Ma Bell wireless telephone in one of the cars.

 

[Brian Roth]

Back on topic @greenhouse_hum ....Thinking about this today, I hope you took copious notes and pictures of the wiring of that console before you gutted it.

Otherwise, I suspect you'll have a difficult time "putting Humpty Dumpty back together again". <g>

Bri

 

[MidnightArrakis]

@MidnightArrakis That small FM station was an interesting place to work for a young "tech nerd". We had an Associated Press teletype machine (enclosed in a "sound proof" ... kinda... housing). Several clocks were fed with "timing" from....Western Union? We had that dedicated Bell line for various remote purposes. A Marti "Remote pickup" transmitter/receiver RF system ("We're live today from the Grand Opening at Waldo's Shoe Store"). The owner had a Ma Bell wireless telephone in one of the cars.

KWHP = KiloWatt HorsePower???

[We had an Associated Press teletype machine (enclosed in a "sound proof" ... kinda... housing)] -- Back during the late-60's, I worked at "the largest broadcast facility in Indiana" that had AM/FM/TV studios -- PLUS -- >> MUZAK << all in one building!!! (I can just hear all of the younger members on this forum reading this and asking themselves, "What the Hell is "MUZAK")??? -- Because all of the studios had so many teletype machines for their incoming news-feeds, they were all put into their own soundproofed room that was located way down the hall from all of the broadcast studios!!! Whenever any type of major news event would take place (i.e., a plane crash, major political speech, etc.), the teletype machines would start going crazy printing out the news reports and combined sound would nearly be deafening!!!

/

 

[Brian Roth]

KWHP......Owner was........ William Hayden Payne. Some folks said the "K" stood for "King". <g>

https://oabok.org/awards/oab-hall-of-fame/oab-hall-of-fame-members/bill-payne/

Bill passed away in 2015.

Bri