Mystery EFT Compressor-EQ Unit

I have a EFT unit with 5 compressors 1 De-esser and 1 Parametric EQ Unit racked in a 2 Unit box. They come from Italy and there's not much I have found on line.
I have been told they were used on the Movie sets to record dialogues during the Cinecitta' era - so maybe late fifties early sixties? Also I learned somewhere they were Italian design but Telefunken components from Germany.
They are powered by a 220 voltage transformer so for now i have used a power converter. They don't sound right, loss of volumes, even after being cleaned they seem unreliable. I was thinking a re-capping to start.

The Compressors mount 2 RM4558L - P7849 transistors. There are 2 NEAN5534 ICs which would place more in the sixties or seventies this project.

The caps are labeled FRAKO West Germany -

I am gonna post pictures of the all unit and the compressor and PS modules.
It would be nice to understand if the Power SUpply could be wired for 110 but there are no writings.  Behind on the PCB it says EFT mod PS+- 24 03+03 A and then 220 near the connector. The unit i wired unbalanced in and out but with XLR in the back with Pin 1 and 3 connected together and 2 is +.

I will greatly appreciate information, suggestions, any tips to bring this back to life...

compressor

Compressor PCB
I have never seen the component on the lower right side, it's cilindric like a cap or a type of FET i have never seen before.

Power Supply

Hey Sage

i found these info you actually provided on Gearsluts on 2010 ! Wow you must have forgotten... time to take some fish oils or gimko biloba....

EFT Tassoni Italian made Limitex - serie 80 - mod LMX and Silenta Noise suppressor

Now with these info lets do a new search.

Marson

FWIW, the date codes visible on a few of the components show 1979 manufacture, so it can't be older than that.

Bri

Hey Brian

thank you sooo much - that is helpful in itself.

Marson is right and I should probably see a memory doctor, afetr his post last night I went to the studio and realized I had the manual! Which includes schematics. It's all in Italian but I can handle that so now I should be recapping 1 and see how it sounds, then probably think of upgrades for the 5534 and the Transistors. It seems like such a good professional build, especially the EQ section. I will scan the manual and post it.

With the manual I found more info. They even have a website: http://www.eft-tassoni.com/
For example in the schematics I saw there is an ptional 1:1 Output transformer for the EQ module so I could upgrade that with a Cinemag or something.

I would bet these compressors are probably optical type units and that the mystery black object contains a light source and gain cell.

I would be interested to know how these units sound.

If they are anything decent then post the schematics.

will do! i will recap and try to test this week though my studio is booked all week long so it might be next week - if they are opto type that would be awesome!
gonna bring them to my tech friend sunday and try to see if he understand what that is... on the scehmatics as far as i understand it seems to be a FET...

Probably a FET in a temperature-controlling "oven". Older NTP compressors used these too.

I don't see power drive circuity for led/ldr type.

Jakob E.

sage said:

I have been told they were used on the Movie sets to record dialogues during the Cinecitta' era - so maybe late fifties early sixties?

Click to expand...

The date on the trimmer places it in 1979 (7922 = 1979 22nd week). No 8pDIP ic's in the 50's and 60's.

Also I learned somewhere they were Italian design but Telefunken components from Germany.

Click to expand...

There is nothing like Telefunken components in solid-state era. Indeed it uses some german components (Frako caps, Preh pots) but also Philips caps, Piher trimmer,...

I bet with a good recap and spray of deoxit, these things would spring back to life. Thanks for sharing the pics! Interesting.

thank you all for the interest in this - I will proceed with recapping and can't wait to see what they sound like - will let you all know -

we wrote to the Tassoni company in Italy that actually made these units and we are asking if there's a way to re-wire the power transformer at 110V instead of 220V.


sage

By the way I see that the values on the Caps are :
47 uF 63V
22 uF 25V
33 uF 16V

now i remember when I had a few modules recapped on my MCI, the tech suggested a mod where the voltage values would be bigger and in some instances also I believe the value itself of the cap.
The reasoning behind that was that the board would have less distortion and more full body, especially on the EQ section, cleaner top end, etc. etc. -

The recapping on my MCI sure sounded like a huge improvement so I ended up recapping it all with the new values, obviously the sonic improvement
could have been just the fact that those old caps were spent.... or is there a truth in that reasoning?

Any suggestions or ideas on that? Shall I keep the values the same or go with higher voltages or values....

sage said:

By the way I see that the values on the Caps are :
47 uF 63V
22 uF 25V
33 uF 16V

now i remember when I had a few modules recapped on my MCI, the tech suggested a mod where the voltage values would be bigger and in some instances also I believe the value itself of the cap.
The reasoning behind that was that the board would have less distortion and more full body, especially on the EQ section, cleaner top end, etc. etc. -

The recapping on my MCI sure sounded like a huge improvement so I ended up recapping it all with the new values, obviously the sonic improvement
could have been just the fact that those old caps were spent.... or is there a truth in that reasoning?

Any suggestions or ideas on that? Shall I keep the values the same or go with higher voltages or values....

Click to expand...

When recapping it is good practice to take advantage of modern technology and upgrade for higher value, higher voltage (although anything above 63V seems overkill on a single-rail 24V system) AND higher temp.
Caps do lose their value with age; recapping generally produces a measurable and audible improvement, even without increasing values.
I noticed there are a few tantalums there. Although I would never use one in any of my designs, I must say they are extremely durable and stable (that is, if they don't fail prematurely). I have found that they generally don't need to be replaced.

I was thinking about replacing Electrolytics for now - I noticed a few decoupling Ceramic discs caps near the 5534s, do you think those should go? and if so would it be a good idea to replace them with Electrolitics?

No. These caps are small value that do not exist in electrolytics. They don't age, they can last probably a couple hundred years.

Also for the compression units, I've found that tantalum in the timing circuitry tend to sound the best (better then the electros i tested against at the time) maybe just something to keep in mind. Also I had some old tantalum caps in a mic-pre and they sounded very noticeably harsher than the electrolytic I replaced them with. I would suggest switching some parts and recording the results to see what you like the best.

Just an update on this:
I should be getting caps in the mail today or tomorrow and after recap and cleaning I will experiment with the optional 1:1 transformer on the EQ - also that will take care of making the unbalanced signal balanced.

I spoke to David at Cinemag and since I am going to pick up a couple of trafos for the 1176 Rev D I am about to start then I will have him suggest an output trafo for this.

After I might want to experiment in trying putting a transformer also in the Compressor units -

Will keep you all posted on progress - yet to scan the schematics but will do today.

Here some schematics for the EQ and the Compressor UNits -

I want to put a OUTPUT trafo on the EQ since it has the option and perhaps on the Limitex as well if there is a way...