Switchable Hi-Z input impedance, how ? - Page 23 - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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
Reply
 
Thread Tools Search this Thread
Old 25th July 2012, 10:05 PM   #221
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
rearranged the inside
tube board and solid state board shifted place
matches the new curcuit layout with BA3 at input instead of output

and thought I would like to see how it looks with tubes
Attached Images
File Type: jpg IMG_7222.JPG (176.6 KB, 28 views)
File Type: jpg IMG_7223.JPG (173.4 KB, 28 views)
  Reply With Quote
Old 25th July 2012, 11:37 PM   #222
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
did a search on 3PDT

under pictures it revealed a ton of info how to connect a LED in bypass
yesterday I was unable to find anything
strange world
  Reply With Quote
Old 26th July 2012, 01:37 PM   #223
shanx is online now shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Google Image Result for http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=11083 &g2_serialNumber=2
  Reply With Quote
Old 26th July 2012, 01:45 PM   #224
shanx is online now shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
Hi tinitus, you will want to do a ''true bypass'' where the section is switched out completely. I posted a link for the basic wiring. To avoid any ''thump'' sound when you switch over, a 1 meg ohm is sometimes added from signal line to ground on the input to that switched section. The Led occupies 1 section of the triple pole, usually switch to ground and complete the circuit. A cool option is to use a dual LED, like yellow/red and switch in either one depending on which ''channel'' or bypass selected.
  Reply With Quote
Old 26th July 2012, 09:40 PM   #225
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Quote:
Originally Posted by shanx View Post
A cool option is to use a dual LED, like yellow/red and switch in either one depending on which ''channel'' or bypass selected.


regarding the 1M ohm
I have seen some suggest to short the input of the bypassed curcuit
But I guessed the 'usual' 1M ohm to ground would do the trick
Attached Images
File Type: png bass pre red green led.png (9.0 KB, 17 views)
  Reply With Quote
Old 26th July 2012, 09:57 PM   #226
shanx is online now shanx  Canada
diyAudio Member
 
Join Date: Dec 2010
Location: Quebec
yeah the 1 Meg will tie the input to ground even when switched over. As you are bypassing completeley that section, any small noise in that bypassed section will be also completely out of the active signal path.
  Reply With Quote
Old 26th July 2012, 10:09 PM   #227
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
right now thinking about where to 'steal' the power for the LEDs

use one half of the +/- 18V from the jfets supply
or take it from the tube heater winding

in any case, it will ofcourse have its own regulator

or simply use a battery ?
sounds a bit 'weird'
  Reply With Quote
Old 26th July 2012, 11:27 PM   #228
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
hmm, a very small trafo should not be any problem
  Reply With Quote
Old 27th July 2012, 02:02 PM   #229
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
this one looks neat
Attached Images
File Type: jpg IMG_7236.JPG (156.2 KB, 14 views)
  Reply With Quote
Old 27th July 2012, 02:23 PM   #230
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
pretty cool little thing

measures 4.7Vdc, unloaded
Attached Images
File Type: jpg IMG_7244.JPG (154.3 KB, 14 views)
  Reply With Quote

Reply


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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Switchable balanced / unbalanced input buffer nigeljking Analog Line Level 4 12th September 2011 01:03 PM
How to design input stage with specific input impedance/pot value mahleriana Tubes / Valves 0 16th November 2009 10:37 PM
Input Impedance Bengali Analog Line Level 7 15th August 2007 11:24 PM
Input impedance nhuwar Tubes / Valves 24 24th July 2007 12:11 AM
Input pot and input impedance Bricolo Parts 1 19th March 2003 02:59 PM


New To Site? Need Help?

All times are GMT. The time now is 03:50 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2