racked telefunken v672s - pictures of non-working modules in

so I wired up one of them without finishing the phantom PS or meter driver and I'm not getting anything. I put pin 2 of the input xlr into 3 of the 672, pin 3 into pin 4 of the 672 which are jumpered to pins 1 and 2 with a 40 ohm resister.
24 volts power is to pin 31.
9 and 10 with 2k2 in serial with a 250k pot.
grounded pins 30 29 21 17 13,
jump 27 & 24,
jump 23 & 22,
output from 19 & 20.
I made an balanced to unbalanced cable to feed it into a channel of my Tascam mixer. All I get is a meter jump when I turn it on and off.

Guess I'll double check averything then wire up the other one and se what happens.

Here are some embarassing pictures showing the non-working v672s, which demonstrate my complete inability to line things up straight.

Did you wire any resistors in series with the inputs. From memory these amps have what is called zero ohm inputs. In other words by connecting a pair of matched resistors in series with the input + & - you detrermine the input impedance, I think I used a pair of 1k2 for my V672/2.

[quote author="Rob Flinn"]Did you wire any resistors in series with the inputs. From memory these amps have what is called zero ohm inputs. In other words by connecting a pair of matched resistors in series with the input + & - you detrermine the input impedance, I think I used a pair of 1k2 for my V672/2.[/quote]

yes I jumpered 1 to 3 and 2 to 4 each with a matched 40 ohm resister then input into pin 3 and 4 so it goes across the resister into pins 1 and 2. I used a 40 ohm resister because my main mic is a beyer m260 ribbon.

on my w295 modules I had to do a bridge on the connector on the module, it was from the power supply OV to the shield of the audio input/ouput. The unit would not function if that was not there. Although it feels rather "not so good" to do this, it was stated in the original manual and no problems so far...

Nice panel.
Kiratronix! Cool.

3 rd box today that looks better than my stuff.
I quit.


:shock:

You're embarrassed by those photos? You must be overly humble. Looks very good to me. Best wishes getting it all going. I suspect you'll sort it when you're ready.

hi Kiira,

I've had success with pins 7 & 8 for the input. Are you sure that your input scheme is known to work?

Lance

I'm sure you'll get it working...nice job!

Good luck!

dam thats a great looking box. I have to ask where did you get such a cool meter?

[quote author="hitchhiker"]hi Kiira,

I've had success with pins 7 & 8 for the input. Are you sure that your input scheme is known to work?

Lance[/quote]

I wondered about that too. 7 & 8 are dsignated "balanced in" as well as 1 & 2. I will try that on the other pre I think. Did you use the input restors on 7 & 8 too?

thanks,

Kiira

[quote author="pucho812"]dam thats a great looking box. I have to ask where did you get such a cool meter?[/quote]

Wow thanks. Thanks everyone. It's all Hamfest found stuff except for the V672s which I paid $60 each for. The meter was $10, the power one 24 V. PS was $12 and the repainted case was $1. I still have to build the phantom power and a driver for the meter but I have the stuff already... I doubt the pair all finished will be more than $200. I'd like to add a line in too. Those modules have 3 large transformers on them. I can't wait to hear my Beyer ribbon through them.

Kiira

yes , 1k2 in series , as Rob said.

cheers,
Lance

Wow! That colour, that meter, those knobs! Absolutelly great.
Very nice box Kiira.

chrissugar

Here's the pinout I always use.

Helsing

1 + Audio in/XLR Pin 2 through 750 ohm Resistor
2 - Audio in/XLR Pin 3 through 750 ohm resistor
3 No Connection
4 NC
5 NC
6 NC
7 NC
8 NC
9 250k Pot Pin 1 (When looking at pot facing the shaft, pin 1 is the leftmost pin.
10 250k Pot Pin 2 (wiper or center pin)
11 NC
12 NC
13 NC
14 NC
15 NC
16 NC
17/21 Bridge with a small piece of buss wire
18 NC
19 + Audio Out/XLR Pin 2
20 - Audio Out/XLR Pin 3
22/23 Bridge with a small piece of buss wire
24/27 Bridge with a small piece of buss wire
25 NC
26 NC
28 NC
29/30 Bridge with a small piece of buss wire/Connect to 0v and Earth Ground.
31 +24vdc

40 or 750 ohms resistors , both work well but what if you want to put a pad on the input, let's say 20dB. You do change the impedance again, right ?

15 years later.... ;-)
We haven´t seen kiira here for a long long time, unforunately. Hope she´s well.

these V672 are weird beasts. I first connected them with 2x780R on the inputs with a -20dB pad. checked in REW. I have a pretty flat curve and a slight roll off above 10K.
Same test without the series R at the input. Again with the -20dB pad. I have a gentle low shelf starting at around 60hz and the same 10K roll off. With higher gain of course.

I don't get the whole point about the series resistors. the manual suggest some, JLM not. Is there a general consensus on how to use them in the real world ?