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tips to calculate amp gains

Printed From: Speakerplans.com
Category: General
Forum Name: Electro Frying Forum
Forum Description: Talk about drivers, processors and mixers
URL: https://forum.speakerplans.com/forum_posts.asp?TID=98419
Printed Date: 27 March 2026 at 10:58am
Software Version: Web Wiz Forums 12.08 - https://www.webwizforums.com

Topic: tips to calculate amp gains

Posted By: _Natty_
Subject: tips to calculate amp gains
Date Posted: 30 April 2017 at 3:21pm

can anyone please help me to choose the right inputs value for this calculator:

http://www.sengpielaudio.com/calculator-amplification.htm" rel="nofollow - http://www.sengpielaudio.com/calculator-amplification.htm

i need input V and output voltage, for these cases:

-powersoft k10 run in stereo at 4ohm: output peak 200V input ??? maybe 4,49V?

-crest 9001 run in stereo at 2ohm: output peak output peak 161V input 2,226 (rated at 4ohm -what thats mean-)

- AB class amp run in stereo a 4ohm: input voltage (this is from the paper) 0,775V output not showed in V just power output in W

thanks to any help

Replies:

Posted By: corell
Date Posted: 30 April 2017 at 7:37pm

U = sqrt(P*R) <=> U² /R = P

0 dbu = 0,775V
0 dbV= 1V

L (in dbu) = 20* log (U/0,775V) <=> U = 0,775V * 10^(L (in dbu) /20)

These are all the formulas needed.

If your amp has a voltage gain of 20db (or a "power factor" of 10) , it will put out 10 times as much as you put in. If it has 26db, it will put out 20 times as much, 32db = 40 times and so on.

For your K10, if you set the voltage gain to be 32db, it will give out its 200V max (meaning 5000w at 8 Ohm) at 5V input...

Posted By: _Natty_
Date Posted: 03 May 2017 at 1:08pm

thanks a lot, i will put all on papers and i will make some calculations... i thing that even tha cable lenght and section should be part of the problem but i think is hard to simulate such hard system with a lot of variables... i will put my mind on it.

if some one would love to collaborate i can even write some web application to host a complex calculator...just some random idea cheers

Posted By: toastyghost
Date Posted: 03 May 2017 at 1:33pm

They have - you're using it, you just need to use the right sections and do some maths and data collation yourself.