ntp limiters

[radiance]

> the selection of the recovery times. i'm a bit stumped


It would also be possible to do this with a simple 1-pole 8-throw switch. Ground the wiper. Start connecting diodes, band-end to the switch, to the ABC terminals marked "0" in Note 2. Position 0 has no diodes. Pos 1 has one diode to pin A. Position 7 has three diodes, to A B and C.

Hi PRR !

Do you have a shemo or something to do that ? I must confess that I don't see the picture to realise this excellent trick !

Cheers !
Bruno.

I don't think there will be a schematic for this. On the positive site..this is an excellent learning oportunity  ;D

read this info on diodes and you'll probably know how to make this switch

http://www.kpsec.freeuk.com/components/diode.htm

Another thing you could do is using a 6 dip switch. I found that I only used one setting. However, to find the setting YOU like best, it's easier to have a rotary so you can instantly switch between settings.

 

[goldvasser]

I'll dig the question ;-)

 

[veermaster]

Andy, Radiance,
don´t you both have/had working units with an added bypass and stereo link switch? Do you remember what you did different from me?
Thanks...
BTW a picture of a switch as described by PRR. I will also replace the Input and Threshold switches of my cards, that´s why there is four channels (A,B,C,D) but for release you will only need ABC. "1" indicates position one of the switch...

 

[matthias]

I think it would be a better solution to measure the voltages at R104 and Q12 for every step and then make it switchable with a simple voltage divider..
I'll work that out later today...

I think the 179-400 is a very capable and good sounding limiter...  I'd like to put my units in a rack but I think it needs some modifications to get more out this great circuit

so does ayone know how to add controls for attack and ratio ???

 

[radiance]

@veermaster : Did you look at the wiring diagram at the end of the pdf file? Can be found on the group DIY gmail account. I wired mine exactly like that diagram...I can mail it to you if you pm me an address were too..

@Matthias: Jaakko was on to something with these cards...maybe he has figured it out ? Dunno..

 

[matthias]

regarding the release switches.. I think I found a simple way to omit the 4051 multiplexers (IC7 / IC8)

you only need two  1x6 switches and a bunch of resistors...

remove R69 and R76

 

[bruno2000]

Here it is, Folks,

  download it from my .mac account. It is as a pdf.


  http://homepage.mac.com/strangeandbouncy


  Enjoy!


        ANdyP

Would you please update this link?
Thanks!
Bruno2000

 

[matthias]

get the full manual with schematic here

 

[veermaster]

I have those documents already but thanks anyway! I used the pin layout posted earlier and following notes to connect my modules:
"Lim. function is disabled by connecting pin 16 to pin 31" I did this but nothing happens, limiting function stays on.
"The control voltage of two units may be linked together to obtain equal gain-reduction" I connected pins 28 of two units but they don´t link.
I built my own 22V PSU for these....
In the PDF they show some connections of before mentioned pins to the original PSU and some "Control Voltage Connector" but it is not shown the internal wiring.

 

[matthias]

bypass and stereo link worked for me.

check your voltages.
check if pin 31 is -9V
connect pin32 (circuit ground) of both units together

 

[Jeremy.Starseed]

On a slight tangent...does anyone have any experience with the NTP 179-340 limiters? For those who never heard of 'em, they're built into Danner modules (to fit in Broadcast racks or consoles).

I have a pair, and would really like to get them working. I haven't even found a schematic. I was told by the tech Bo Hansén that they would definitely need adjustable release to be of any use...and that's where the matter settled, and stagnation came to visit  :

 

[veermaster]

bypass and stereo link worked for me.

check your voltages.
check if pin 31 is -9V
connect pin32 (circuit ground) of both units together

I doubt that pin 31 is -9V refered to GRND: the documentation says the modules are to be fed with 22-32V DC at pin 29. If I understand the schematic right this voltage is converted to 9V by a LM317 (Output of pin 2 of this IC is stated as "+9V"). Pin 31 should be 0V (=GND in my case). It looks a little irritating in the schem saying ":9V" but I think that´s just some oldskool writing for "refered to this pin "+9v" is, well, 9V". I hope I can make myself clear  :-\
Pin 32 is just connected to the shielding metal plate under the PCB.

BUT: I just realized that there is different versions of NTP 179-400 and I have one branded as version E. With this one my Bypass Switch works just as it should!
Well, the other modules don´t have a Letter to them, maybe their pin layout is little different, does anyone know?
Thanks again, Emre

 

[veermaster]

This model E I was talking about has a Bypass switch on the frontplate (the others don´t). This is what it does:

I tried this with another module and it works. Well, the meter still shows limiting but I could just deconnect it by the same switch.
But I still don´t have a clue how to stereo link these modules. Linking Pins 28 of two such modules just does not work  ???

 

[veermaster]

I think my stereo link works  When I watch the input of my DAW I can see the link switch affecting thse second channel. But the connected meters behave strange: only one meter moves per time, the one which has more input.
So when I have the same sinus on both inputs with stereo link engaged but the right channels sinus gain is higher the needle of the second channel just drops and vice versa. I can never get them to show the happening limiting at the same time though both channels are actually limiting (as seen in my DAW).
What could I do?
Thanks, Emre

 

[radiance]

I'm sure you have but just in case...
Have you recaped both cards?...i.e. those red cans need to be replaced...

 

[veermaster]

I'm sure you have but just in case...
Have you recaped both cards?...i.e. those red cans need to be replaced...

I heard about especially this type being famous for dying and I have some Panasonics already on my order list...
But my units work and I don´t think these little red elkos could be responsible for only one meter movin at a time, could they?

 

[radiance]

Dont know where they're at exactly in the circuit, but I've seen weirder stuff...

 

[matthias]

I think my stereo link works  When I watch the input of my DAW I can see the link switch affecting the second channel.

is the amount of gainreduction on both channels the same? if not, have you calibrated the threshold trimpot on the pcb?

But the connected meters behave strange: only one meter moves per time, the one which has more input.

does the other meter behave correctly, when you disconnect the stereo link?

I just looked at the schematic and I think if you replace the diode (d19) with a piece of wire the meter will receive the cv voltage
of the other channel (when both voltages are linked) ... but I must say that this is only a guess and I haven't tried this yet... 

 

[veermaster]

@ radiance: Pin 27 is connected to + of meter, - goes to Pin 26 (or GND).
Well, you´re right, of course I´m happy that these units are working as they should an this strange behavour of the meters when in stereo link mode is just an aesthetic drawback, but still...

@matthias: very interesting, I will try that in a few minutes.

 

[radiance]

Dont know where they're at exactly in the circuit,

What I was trying to say: I don't know where those red can capacitors are in the circuit.
If those ageing red cans are in the meter driver circuit they might cause some strangeness I suppose...

When I racked my ntp cards I did not use a meter, partly because there was not much space left in the 1 unit case. However, I must say that not having a meter made me listen much better to what I was doing.
Visual feedback is great, but since hour eyes give the primary perception impulse (compared to all other impulses we get) we tend to make decisions mostly based on that (visual feedback that is).