NTP 179-400 Stereo Link

[andow]

I have two NTP 179-400 limiter cards that I racked some time ago and they are working fine and just sound lovely. There is one thing however that has been puzzling me: when linked for stereo operation, only one meter shows the gain reduction and the other one drops to zero (signal path is not affected by this - it's really just the metering). It's always the meter of the channel with less gain reduction that shows zero, so it's not always the same channel.

In the attached schematic (see pdf for full resolution) you can see pins 26 and 27 where the meter is connected (I'm using a cheap amperemeter from Ebay - internal resistance is 1k, so within the specs of NTP). Linking two cards is done by connecting pin 28 of both cards together.

Has somebody racked these for stereo operation with meters and solved this problem?

 

[mjrippe]

I racked a pair of these many years ago and I do not recall having this issue. Definitely check the diodes D13 and D19 in both modules.

 

[andow]

I racked a pair of these many years ago and I do not recall having this issue. Definitely check the diodes D13 and D19 in both modules.

Thanks for your help! I already checked these, they measure fine...

 

[noiro]

Just bought a pair of these, looking forward in building my 1U rack. Of course I will have some questions. At the moment I'm looking at the Lorlin binary coded switches, Mouser have some but which one BCK10XX ?

 

[musika]

For the 179-400 you need a hexidecimal switch ( not complimentary ), so I think this would work:

https://www.mouser.com/ProductDetail/Lorlin/BCK1006?qs=LLUE9lz1YbfPwht6yYvaAA==

Others on the forum can confirm.

 

[andow]

Yes, that's the one, you'll need Code 033.
With this switch you can either have all positions but no end stop, or an end stop but then you'll loose position 0000.

 

[diggy fresh]

I got inspired to rack my card by this thread. i'm in the process now.

did you fix the issue?

I figured out almost everything with the pdf but i have a question about the "limiter off" switch.

Pin 16 is "limiter off", we see on the last page of the pdf (the stereo rack),
they connect pin 16 to pin 12 on the NTP psu to turn off the limiting.

What are they connecting pin 16 to? Is it ground? Vcc? i cannot find the info in the pdf or pin 16 on the schematic.


Anybody figured it out?

Thanks.

 

[andow]

I got inspired to rack my card by this thread. i'm in the process now.

did you fix the issue?

I figured out almost everything with the pdf but i have a question about the "limiter off" switch.

Pin 16 is "limiter off", we see on the last page of the pdf (the stereo rack),
they connect pin 16 to pin 12 on the NTP psu to turn off the limiting.

What are they connecting pin 16 to? Is it ground? Vcc? i cannot find the info in the pdf or pin 16 on the schematic.


Anybody figured it out?

Thanks.

It says in the manual:
"Lim. function is disabled by connecting pin 16 to pin 31."

 

[diggy fresh]

It says in the manual:
"Lim. function is disabled by connecting pin 16 to pin 31."

oops i missed that.. thanks!

 

[siox]

For the 179-400 you need a hexidecimal switch ( not complimentary ), so I think this would work:

https://www.mouser.com/ProductDetail/Lorlin/BCK1006?qs=LLUE9lz1YbfPwht6yYvaAA==

Others on the forum can confirm.

Hello,

I just ordered two of these Limiter Modules and also want to put them in a customized case. Thanks for all the useful info on this forum!
I have two questions:

Will this switch also work for threshold and level?

I have no experience with VU Meters at all - according to the service manual and the specs there i would order this one:
Meter
can I connect this meter directly to the designated pin's of the connector?

Thank you and regards,
Georg

 

[siox]

Hi,

I measured the switches today - if someone else needs that info: the Gain and Lim. Level switches also are Lorlin Code033 types. Its the same code but in reversed order.