Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

soundcard protection Z ???
soundcard protection Z ???
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
Thread Tools Search this Thread
Old 21st May 2010, 12:47 AM   #1
grindstone is offline grindstone  United States
diyAudio Member
grindstone's Avatar
Join Date: Jun 2007
Location: GMT-6
Default soundcard protection Z ???

Trying to make a little nose to nose zener thing with an R divider to protect my soundcard input to measure an amp and am a bit hung-up about Z of the divider that ends up in there. was hoping just some passive thing would work. Thinking this is trying to "transfer" V so I want to preserve as much bandwidth as i can by staying 1:10 at least (???)

Namely, if my amp terminals have 8R dummy loads and the soundcard Zin is 10k, the divider should look like min 8*10 ~80R to the amp and the card should see 10k/10 ~1k looking backwards? I mean, bandwidth can be lost from amp to divider and from divider to soundcard, right?

I read in another thread that people were using something like 100k Rseries for direct circuit (not amp output) connection. Also higher values were recommended to not blow output transistors and stuff. This is definitely not my app--I just want to measure low-watt tube stuff.

I just don't understand how 100k doesn't make all the soundcard input all rolled-off. I was thinking that a soundcard with 10k Zin would want to see a k or so so that's about the max series R in the divider that would be usable. I'm missing something embarassingly fundamental but am not to proud to come begging for a steer

  Reply With Quote
Old 21st May 2010, 01:21 AM   #2
davidsrsb is offline davidsrsb  Malaysia
diyAudio Member
Join Date: Dec 2005
Location: Kuala Lumpur
Don't depend on the input impedance.
Use a L pad with 10k in series and 560R to ground in parallel with the sound card input, giving about 500R

This gives 20:1 attenuation, protecting to +/- 50V from the amplifier
These relatively low resistances will have a wide and flat bandwidth
  Reply With Quote
Old 21st May 2010, 02:02 AM   #3
grindstone is offline grindstone  United States
diyAudio Member
grindstone's Avatar
Join Date: Jun 2007
Location: GMT-6
Thanks so much -- I really appreciate the guidance
  Reply With Quote


soundcard protection Z ???Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
soundcard and laptop rinx Multi-Way 3 16th November 2007 08:33 PM
SPDIF from Soundcard orangeshasta Digital Source 7 26th July 2007 06:03 AM
Help with soundcard... please!! ch83575 Multi-Way 1 19th February 2007 03:47 PM
speaker protection (OR) overload protection myanmar Solid State 7 13th July 2006 09:21 AM
Help with noisy soundcard davidlzimmer Digital Source 2 25th February 2006 08:51 PM

New To Site? Need Help?

All times are GMT. The time now is 06:21 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio