Alternative to JLM VU buffer Boards

[Gold]

Many Quad-Eight boards during my era there (early seventies) had this feature standard.

I used a pair of Quad Eight MM312S in my mastering setup for over 20 years. Just recently retired for EQ’s I built for an A/B path lacquer cutting console. They are my favorite console EQ of all time. I like it better than the usual suspects. They came out of a large console in the UK. I caught the console with about the third owner. It was a large recording console. I think I remember hearing it was a 1975 commission. It was 32 channel and 24 bus with a 24 channel monitor and eight VCA groups. That console was in rough shape but sounded fabulous. In todays world it would probably be restored. In the early 90’s it was decommissioned for an Amek that worked well.

George Horn is retiring and selling his cutting setup. He has a Quad Eight A/B path cutting console I’m drooling over. I don’t need it and can’t use it but I want it so bad.

 

[MisterCMRR]

Quad-Eight boards were arguably some of the best analog ever made. The boards were uncompromising and used by a huge number of the best known studios in the world. They were expensive (typically $50-150k in early 70's dollars) but built like battleships. For example, front panels were thick aluminum laminated with Formica (in customer-selected color/texture) and markings were engraved and filled (sometimes with luminescent paint for use in dark environments (like the 3-operator scoring stage I visited once at MGM). Faders, made by Gliss, used resistance wire wound on glass rods with easy to clean and adjust wipers. Signal paths used minimal amplification and the amplifiers were a hybrid module AM-4 made for QEE by Fairchild Semi and supply rails bipolar 24 V - resulting in lots of headroom. Transformers were custom-made by Ed Reichenbach, and became the starting point for the improved designs created by Deane Jensen. Deane left QEE in 1971 to start Jensen Transformers after interviewing and endorsing me as his replacement at QEE. Little did I know at the time that our paths would cross again nearly 20 years later and he'd pass ownership of Jensen to me! May Deane rest in peace ...

 

[Gold]

The MM312S I have use the discreet five transistor amp. I like that version better than the 310 series that uses the AM10 opamp.

The rotary switches are extremely high quality. They have been in constant use since being manufactured and I’ve never had to do anything except exercise the switch. That hardly ever needs to be done. I expected them to work trouble free and clickless. They did for over forty years. Impressive.

The faceplates look to be 3/16” aluminum with the formica laminate. Beefy.

 

[pinebox]

Figured I would ask here instead of making a new thread. Are there any buffer cards for multiple meters out there? I am modifying a friends Amek to use the VU panel from an earlier model instead of the LED style that came with his Angela. I have been looking at the JLM boards but I need at least 26 of them and was wondering if anyone made 24 or so on one card? Wishful thinking I’m sure but still thought I’d ask.

 

[MidnightArrakis]

Figured I would ask here instead of making a new thread. Are there any buffer cards for multiple meters out there? I am modifying a friends Amek to use the VU panel from an earlier model instead of the LED style that came with his Angela. I have been looking at the JLM boards but I need at least 26 of them and was wondering if anyone made 24 or so on one card? Wishful thinking I’m sure but still thought I’d ask.

HEY!!! -- Find a VU-meter driving circuit that you like, send me the schematic and I will make you a 26-Channel VU-meter PCB (and, chassis or whatever you want to put this PCB into). And/or.....provide me with the mechanical dimensions of your meter-bridge and I could then design a PCB that would attach to all of the VU-meters!!! Sound like a plan???

/

 

[MidnightArrakis]

Figured I would ask here instead of making a new thread. Are there any buffer cards for multiple meters out there? I am modifying a friends Amek to use the VU panel from an earlier model instead of the LED style that came with his Angela. I have been looking at the JLM boards but I need at least 26 of them and was wondering if anyone made 24 or so on one card? Wishful thinking I’m sure but still thought I’d ask.

Here are some VU-meter schematics to help you get started on your project:


https://groupdiy.com/attachments/ia...u-meter-buffer-amplifier-schematic-pdf.83655/

 

[macleod69]

Hi everybody !

I just found a vu meter pcb buffer with led overload at proaudiogc.com.
This is exactly what I was looking for for my project!

https://proaudiogc.com/pcb-shop/vu-...rmet-de-transformer-facilement-et-facile.html

 

[boji]

Hey Ian,
Nifty idea. This might be a dumb question, but was wondering if those buffer input xformers protect the VU's as well?
I'm supposing so, if they saturate easily. I ask because I went with difficult-to-find modutecs and have already burnt one out.

Looks like they may have an early roll off which could be useful in some circumstances as well.

 

[ruffrecords]

Hey Ian,
Nifty idea. This might be a dumb question, but was wondering if those buffer input xformers protect the VU's as well?
I'm supposing so, if they saturate easily. I ask because I went with difficult-to-find modutecs and have already burnt one out.

Looks like they may have an early roll off which could be useful in some circumstances as well.

The reason for using them was to maintain a balanced floating input. I was concerned their frequency response might not be up to the job but those little TRIADs are remarkably good. I measured only 1dB down at 20KHz. They are certainly small enough that they could saturate at high signal levels at low frequencies but mid band I would be surprised if they did. Protection of the VUs was not something I was thinking about. However, the fact the whole circuit runs of a single 12V supply limits the maximum current into the meter to less than 4mA.

Cheers

Ian

 

[Murdock]

Hi everybody !

I just found a vu meter pcb buffer with led overload at proaudiogc.com.
This is exactly what I was looking for for my project!

https://proaudiogc.com/pcb-shop/vu-...rmet-de-transformer-facilement-et-facile.html

Has anyone ever ordered something from proaudiogc.com?
Are they any good?

 

[TimG]

Has anyone ever ordered something from proaudiogc.com?
Are they any good?

I bought some Grayhill switch PCBs for a future project, last year. It was a very normal transaction and they came within a couple weeks as I recall.

 

[Little Geoff]

On the subject of VU driver cards and meters I've just found a couple of SSL driver cards. CF82E66 to be exact.
As I don't have any service data anymore I wondered if anyone could point me to where I might find details of the cards especially the pin-out of the ten way connector.
I have the matching meters which are Sifam R22. I prefer the scale on my Amek meters which are AL22. Just noticed the pointer of my Amek phase meter which is a Sifam A22AF matches the R22.

Thanks
Geoff

 

[kags]

This might help - slightly different since it included the status LED, but probably a good starting point. A couple of years ago I had to draw this out for a 2-channel outboard meter display and I found a few very similar schematics online - maybe even the JLM one was close enough to jump off from when deciphering this one...