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

LOFO Pre/Power Amp Switch
LOFO Pre/Power Amp Switch
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 10th August 2018, 02:16 PM   #1
quyda is offline quyda  Viet Nam
diyAudio Member
 
Join Date: Feb 2005
Location: Hanoi
Default LOFO Pre/Power Amp Switch

Hi,

Is there a simple switch that will turn Preamp & Power Amp in correct order, that is Power Amp = Last ON, First OFF (LOFO)?
Im a lazy *** and one a foolproof way to turn my equipments.

Thanks,
Quy
  Reply With Quote
Old 11th August 2018, 10:07 AM   #2
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
You may be able to find a 3-position toggle switch, or a mains-rated rotary switch.
  Reply With Quote
Old 11th August 2018, 06:27 PM   #3
quyda is offline quyda  Viet Nam
diyAudio Member
 
Join Date: Feb 2005
Location: Hanoi
Im thinking about Arduino + 2Ch relay, but im not sure about when the main power was suddenly cut off to the relay board, both relay will probably go off at the same time.
  Reply With Quote
Old 11th August 2018, 07:32 PM   #4
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by quyda View Post
Is there a simple switch that will turn Preamp & Power Amp in correct order, that is Power Amp
= Last ON, First OFF (LOFO)? Im a lazy *** and one a foolproof way to turn my equipments.
Use a regular switch and an LM555 timer controlling an AC relay, for adding time delay for the amp.
The LM555 should immediately reset upon power off, to deal with AC power line drop outs.

All you really need, though, is delayed unmuting on the preamp outputs. Then both preamp
and amp can be safely switched on at the same time. The LM555 should immediately reset
upon power off, to deal with AC power line drop outs.

What kind of amp/preamp is this for?

Last edited by rayma; 11th August 2018 at 07:52 PM.
  Reply With Quote
Old 12th August 2018, 02:12 AM   #5
quyda is offline quyda  Viet Nam
diyAudio Member
 
Join Date: Feb 2005
Location: Hanoi
Hi,

Im running my L15-D after a JC-2 (purely for volume control atm).
Problem is when cut off power of both amp at the same time, the JC-2 would give a loud thump.
But the LOFO setup that I want can be use with any pair of Amp/Pre.
  Reply With Quote
Old 12th August 2018, 02:19 AM   #6
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by quyda View Post
Hi,

Im running my L15-D after a JC-2 (purely for volume control atm).
Problem is when cut off power of both amp at the same time, the JC-2 would give a loud thump.
But the LOFO setup that I want can be use with any pair of Amp/Pre.
It's a China JC-2 clone? I have one of those. I think the arrangement in post 4 would work for you,
just add the circuit in an external box.

You can add a pass-through box with a series resistor and a shunt relay to ground, controlled by
the LM555. This box would need its own power supply. The timer should reset immediately upon
turnoff, to deal with AC line dropouts.

You would plug the box's power cord into a switched AC outlet on the preamp, so the box can sense
that the preamp power has been switched. Or if you use an outlet strip to switch everything, plug
the box into that.

There are commercial AC sequencing boxes made for this kind of purpose, Audio Research made some
rather expensive ones years ago.

Last edited by rayma; 12th August 2018 at 02:32 AM.
  Reply With Quote

Reply


LOFO Pre/Power Amp SwitchHide 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
Amcron DC300A replace power switch with 2 wire switch simondolanbass Solid State 3 11th September 2017 01:07 AM
Capacitor Across Power Switch to Control Switch On Noise? DreadPirate Analog Line Level 20 21st April 2013 02:58 PM
Power switch driver board(Momentary switch) + output relay board(delayed ON/fast OFF) Neutrality Headphone Systems 1 20th March 2013 10:57 AM
Adding a 12V power trigger switch to Electrocompaniet Power Amp maxzimum Solid State 0 11th April 2008 01:54 PM
Using a momentary switch for main power switch? FullThrottleRic Parts 9 25th June 2002 08:23 PM


New To Site? Need Help?

All times are GMT. The time now is 06:25 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki