Fester's TG12413 in 51X format.... TG51X? Getting closer.........

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Well-known member
Jul 17, 2006
Well, I want to add it to my 51X rack, and have original transfer console's docs and Fester's (;) design.

The only option is to use 51X rack, the beast requires +/-24V
(actually, +/-28, but it runs internally at +/-20 , +23 and -27), more about this see below.

It can be done in 2 slots, no enough room for all components in 1 slot.

For now, I finished the PCB design of audio part, and freakin' arround control.

For now, it is close to "original" as possible, with addition of SC HPF, option for INPUT pot (switch),
HOLD, ATTACK, and 11 positions for RECOVERY.

I used big as possible packages for all possible audio components; output can be made transformer- or -less.

No "IRON/CLEAN" option, no room even in 2 slots.

Powering the beast.
+/-28 Volts in original brought down to +/-20 and +23, -27 internally.
+23/-27V used for output stage, and can be +23/-24 with proper scaling of 2 resistors, to be at perfectionist's side.
(it runs at -24 without any mod as well).
So, it 100% OK to run this circuit at +/-24.

Couple of questions.

Should I stick to original 6 positions release and no attack?

Should I use HOLD or input control or both?

Any options/mods?

Any thoughts welcome!
Sometimes it's good not to give too many options. Old school. Hold and 6 pos release was/is perfectly fine imo...as long as it's sounding and working well otherwise. 

EDIT: A couple different attacks...of course is good idea.  :)
I only toyed shortly with a TG1 once but instantly thought that 6 positions for release is not enough. If you could get us a few mor release times that´d be great.
First one is like 'mastering' version. But what is needed for single channel version?
@jensenmann: I had same feel 3 years ago when experimented with this thingy first time)
6 steps for release never enough.
Options, steps and total recall, here we are nowadays.
The thing is people who never can say "Close the mix, it sounds good for me" like it was before digital era..
They leave mix in the box, than come to studio day after and say "Everything's fine, BUT take the vocal upfront by 0.75 db".
(Heh, don't believe? True story. Amazzzing, aye, 0.75 db!)
No more people who have enough responsibility and take decisions with what we have...
More rev to snare and slower compression. Not this kinda, faster a bit. You don't have in-between? Argh!
"Customer" always want to check his mix at the car, show to girlfriend and take advice from friend.
This way, we have an automation, total recall and protools.
From the other side, I always like to have more options to have a choice.

Well, just a thoughts :)

After some thinking.....

We can have all original odd steps and add even in-between, for recovery.
Second step for ATTACK will be "original", the rest "Original Close as Possible Nazi" can never use
or stop the attack switch at second position :)
No blasphemy from DaoiZm Katolic Holy Land Church in any case, I promise ;)

I will keep TG51X close as possible to oldy, all additional stuff can be put in "orig" position.
Most care already taken to sound path, it done as-is.
Hope, everybody will be happy with 11 steps for release (can be changed back to 6 or use odd steps),
11 steps for attack (2nd is original, don't like to use-short/install fixed resistor), with INPUT 21-pos. switch or pot
(don't like to use-short), sidechain HPF (don't like-short the switch), and with HOLD control.

desol said:
First one is like 'mastering' version. But what is needed for single channel version?

TG51X IS the single channel version.
Use pots instead of stepped INPUT/OUTPUT controls, it will be "non-mastering version"))
INPUT/OUTPUT 21 step Elma's may be used and fits fine.

Huh.... Cool... More thoughts? Ideas?
Igor said:
desol said:
First one is like 'mastering' version. But what is needed for single channel version?
TG51X IS the single channel version.

This was only rhetorical question pointing out philosophy in simplicity. Seems many of the best tracking compressors still are the ones with almost the fewest controls.  ;)
I haven't quite finished my TG comp - so I can't give any specific feedback...

BUT - i've always found a SC HPF to be a very useful option on almost all compressors so i'm glad you are including that one :)

I also vote for variable attack, if possible - people who don't want it can just leave it at the default setting or hardwire it.

I also agree that 100% stepped controls are VERY useful these days - everyone expects total recall.... plus, it's nice not to have TOO many options sometimes!

Thanks IGOR! keep up the good work  8)
Agree with both of you, guys. As been spoken, it is possible to build it without any additions.
Haima: do you have my skype, if need hardcore troubleshooting?

Next thing, is 2N4898, 2N4910, OA202, ELMA switches sourcing.
Some interesting info, BTW, from transfer console manual:

2.1.2 Signal levels

Signal voltage levels are expressed in dBv, this being the voltage level in decibels with respect to 0.447v
(this being the r.m.s. voltage across a 200Ohm resistor when dissipating one milliwatt).
The figures quoted are not all strictly accurate as they do not, in general,
take into account the loading effect of a high impedance load across a 200Ohm or lower impedance source.

In the manufacturing test specifications which require more precision, sending levels are expressed in dBi,
this being the indicated sending level of a 200Ohm Gain Set. At an indicated level setting of 0dBi,
the gain set would deliver a zero level signal, 0dBm, i.e. 1 milliwatt, into a 200Ohm load.
Thus at the output of the Gain Set when loaded with 200Ohm, dBm, dBv and dBi are numerically equal.
If the output is completely unloaded then dBV=dBi + 6.02

2.1.4  Input Transformers
The left and right signals from the transpose button pass to input
transformers which step down in the ratio of 1.732 : 1 thereby reducing a standard
line level input signal of l.228 V (+ 4dBm in 600) to 0.709 V (+ 4dBm in 200),
this being the standard internal interconnection level.
Since the input impedance is
bridging, the transformer loss is negligible.

For vertical limiter, Zeners on schemo are: BZY88C5V1

Output amp is inverting, can be summed with direct input signal.........

Have to DIG this!
Some news.... Audio:

(many input/output transformers options preserved ;)


  • TG_51X_1.png
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And 2 versions for front panel: "original" (single pcb at left side) and full-featured (2 pcb's arranged as sandwich, right top/bottom).


  • TG_51X_2.png
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