Passive monitor controller input output impedance meaning
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 PA Systems A forum for discussion of all parts of a sound reinforcement or DJ system: loudspeakers, mixers (desks) etc.

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 21st December 2017, 09:23 AM #1 Zaharescu Mihai   diyAudio Member   Join Date: Dec 2017 Location: Bucharest Passive monitor controller input output impedance meaning I hope I'm not flooding the forum with simple questions, if I do please let me know. I'm having trouble understanding the input and output impedances from the specifications of the Nanopatch+ manual [1]. I always thought that a passive monitor controller was just a collection of synchronized potentiometers on hot and cold wires. This would mean that if set at maximum volume it would act as a direct connection and if set at 0 it would be an open circuit (idealy). However, in the manual they state that the input impedance is 5 Kohms and the output is 0-5 Kohms. Interpreting this directly I understand that the driving device always sees 5 Kohms at the output, no mater what is after the passive controller and at which volume the controller is set (I don't know how this can be achieved with a passive device), and the device that is driven sees from 0 to 5 Kohms at the input, depending on the volume of the controller (thus meaning that at minimum volume it will short the input of the device that is driven). Could it however mean that the driving device sees at the output 5 Kohms + the impedance of the driving device, and the device that is driven sees at the input 0-5Kohms + the output impedance of the driving device (thus not shorting the input). For example: processor (out Z: 50 ohms) -> passive controller -> power amplifier (in Z: 600 ohms) A: - the processor sees 5 Kohms at the output. - the amplifier sees at the input 0(short) ohms at minimum controller volume and 5 Kohms at max volume B: - the processor sees 5.3 Kohms at the output - the amplifier sees at the input 50 ohms at max volume and 5.05 Kohms at min volume Which of the two chases is correct, if any? Thank you. [1] https://www.jblpro.com/ProductAttach...ual_090215.pdf Last edited by Zaharescu Mihai; 21st December 2017 at 11:38 AM.
 21st December 2017, 09:36 AM #2 GeorgK   diyAudio Member   Join Date: Jan 2005 Location: Vienna With Volume full up, the load for the source is the 5k Pot resistance in parallel with the input of the next device, so eg. 5k||600 = 535 Ohms. The receiving input (the amp in your case) is then being driven with the source impedance of the sending device. Output impedance of the Controller gets higher when turning volume down, just as the load resistance of the driver inreases until the latter reaches 5k when pot is fully down. Cannot draw a schematic from here that makes this clearer, but maybe somebody eles will?
Zaharescu Mihai
diyAudio Member

Join Date: Dec 2017
Location: Bucharest
Is this correct (attached image)?

Meaning that:
- when R2=0 : the processor sees 535 Ohms and the amplifier 49.5 Ohms (full volume)
- when R2 = 5K : the processor sees 5K and the amplifier 0 Ohms (mute)

It's a bit unclear about the 0 Ohms impedance, maybe I got something wrong...

 sorry, 600 instead of 300 in the image, but the idea is the same.
Attached Images
 Passive-Monitor-Controller-Impedances.jpg (181.4 KB, 21 views)

Last edited by Zaharescu Mihai; 21st December 2017 at 11:38 AM.

 21st December 2017, 12:35 PM #4 GeorgK   diyAudio Member   Join Date: Jan 2005 Location: Vienna the schematics are not easy to read because you drew GND on top, but ok, you got it. That the amp actually sees zero with volume turned down does not mean you have zero source impedance. This is the impedance the amp sees, but the value is useless in your application. As you go near zero with your volume, the signal hast to pass more and more of the 5k resistor, so lower input impedances produce more loss at a given pot position. So near zero it has almost grown to 5k. Amongst others, his theoretically may imply more interference, but practically will do no harm as long are cables are kept *short*.

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post kategra84 Analog Line Level 1 20th February 2013 01:26 PM redmaster Analog Line Level 2 2nd December 2011 12:02 PM hasselbaink Analog Line Level 1 8th September 2011 08:53 AM pedrito Analog Line Level 3 30th June 2009 07:58 AM echosystm Everything Else 0 6th April 2007 03:17 PM

 New To Site? Need Help?

All times are GMT. The time now is 09:14 AM.