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

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

db gain vs input sensitivity
db gain vs input sensitivity
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 11th March 2017, 10:20 PM   #1
georgehifi is offline georgehifi  Australia
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
Default db gain vs input sensitivity

Just to prove to my friend if a power amp has 24db of gain, what is it's input voltage sensitivity for full 90w output, he's watching

Cheers George
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com

Last edited by georgehifi; 11th March 2017 at 10:42 PM.
  Reply With Quote
Old 11th March 2017, 10:29 PM   #2
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Jands - Sensitivity, Gain, Power, Volume - Different Words For The Same Thing?
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 11th March 2017, 10:53 PM   #3
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: limbo
Efficiency and sensitivity conversion - loudspeaker percent and dB per watt and meter loudspeaker efficiency versus sensitivity vs speaker sensitivity 1 watt = 2,83 volt box chart - sengpielaudio Sengpiel Berlin
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 11th March 2017, 11:12 PM   #4
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by georgehifi View Post
if a power amp has 24db of gain, what is it's input voltage sensitivity for full 90w output.
90W into 8R --> VxV/8R=90 W --> V= 26.8V output voltage at 90W

Gain=24dB --> 24=20 x log(26.8/Vin) --> Vin= 1.69V input voltage for full output voltage/power

All voltages in Vrms.

Last edited by rayma; 11th March 2017 at 11:19 PM.
  Reply With Quote
Old 12th March 2017, 01:24 AM   #5
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by georgehifi View Post
Just to prove to my friend if a power amp has 24db of gain, what is it's input voltage sensitivity for full 90w output, he's watching

Cheers George
Incomplete question, you did not mention load impedance.
Without that, any answer is just a guess.

Unless it includes "all answers", meaning a sensitivity vs. impedance table.
__________________
Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
  Reply With Quote
Old 12th March 2017, 01:41 AM   #6
georgehifi is offline georgehifi  Australia
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
Quote:
Originally Posted by JMFahey View Post
Incomplete question, you did not mention load impedance.
Without that, any answer is just a guess.

Unless it includes "all answers", meaning a sensitivity vs. impedance table.
90w 8ohms

Cheers George
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  Reply With Quote
Old 12th March 2017, 09:33 AM   #7
andyr is offline andyr  Australia
diyAudio Member
 
Join Date: Nov 2003
Location: Melbourne (Oz, not Florida!)
Quote:
Originally Posted by JMFahey View Post
Incomplete question, you did not mention load impedance.
Without that, any answer is just a guess.
Or you assume the customary 8 ohms, as Ray did.

Andy
  Reply With Quote
Old 12th March 2017, 09:37 AM   #8
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Or you hand him a fishing rod instead of a fish
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 12th March 2017, 02:32 PM   #9
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Surely on this forum it should be the parts for him to make his own fishing rod?
  Reply With Quote
Old 13th March 2017, 10:29 AM   #10
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
Rayma guessed the speaker impedance correctly and gave the correct answer for full power sensitivity.

Vmax = sqrt(max power * Speaker Impedance) = sqrt (90*8) = 26.8Vac

Gain factor = invLog(dBgain / 20) = inLog(24/20) = 15.85

Sensitivity = Vmax / Gain factor = 26.8/15.85 = 1693mVac

Any CDP and similar digital source will need to be attenuated to prevent the amplifier from clipping.
__________________
regards Andrew T.
  Reply With Quote

Reply


db gain vs input sensitivityHide 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
Unity Gain Power Amplifier Voltage Gain = 1 (0 dB) - where are these amps ? tiefbassuebertr Solid State 10 3rd July 2017 11:22 PM
What is the sensitivity(dB)of JBL 123A ? reellike Subwoofers 1 16th November 2014 02:42 PM
tweeter with 98 db sensitivity slr 5000 Multi-Way 21 15th September 2013 11:40 AM
DB sensitivity between different drives matthias125 Multi-Way 9 22nd October 2012 08:04 AM
Sensitivity dB Calculations 69stingray Multi-Way 4 5th July 2007 12:25 AM


New To Site? Need Help?

All times are GMT. The time now is 03:30 AM.


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