Notices
Audio Systems Find answers to all of your stereo, speaker and other audio technology questions here.
Sponsored by:
Sponsored by:

DMM gain setting

 
  #1  
Old 05-08-2016, 04:17 PM
slyedog's Avatar
slyedog
slyedog is offline
Supporter
Thread Starter
Join Date: Aug 2013
Location: Hawkeye state
Posts: 3,789
Received 240 Likes on 177 Posts
Default

The sticky is flooded and no since clouding it up. Im not trying to get in a pissing match nor talk anyone down here. There are some methods how testing with dmm being left out here and since nutz isn't around as much I'm throwing this out there how I was taught to do so. Using this as a USEFUL discussion only!!! I am trying to grasp the ac voltage dc current concept. Lets use a JL xd400/4v2 as an example amp. 75x4 @4 ohms. I will connect my dmm leads to channel 1 +/-. At those terminals with 4 ohm load I should see 17.32v. Now I can go check the bridged output of channels 1&2 . It will still show the 4 ohm output if I am doing this correctly of 28.2 . You are running the 2 channels in parallel so the voltage will change. That's how the power is double from the 2 ohm rating of the amplifier. This chart JL uses is kind of a handy reference. I personally have never used a DMM to test as ear was always adequate until the high end setup I now have. I used the scope and DMM to PROTECT my investment. Not squeeze every drop of unclipped power to it. I have been applying DC theory to A/C which is different. In dc parallel current increases but voltage does not. I apologise if this is hard to understand. I am trying to grasp how some figures are given. Example my amp bridged displayed 32.4 v at near clipping, In bridged mode. But others are showing higher per channel than my voltage per speaker. Now is that peak voltage being measured? Then if so I am right on point with my thought process. So the single channel voltage will be .614 of the bridged voltage.
 

Last edited by slyedog; 05-08-2016 at 10:08 PM. Reason: changed some figures
  #2  
Old 05-09-2016, 09:21 AM
AAWAV's Avatar
AAWAV
AAWAV is offline
Road Warrior
Join Date: Aug 2013
Location: Las Vegas
Posts: 1,505
Likes: 0
Received 28 Likes on 19 Posts
Default

when bridging, you do not take the channels parallel but in series.
it stacks the 2 AC signals (1000Hz test sine wave) "on top of each other", as 1 of the channel is 180 degrees reversed.
Scope is simply the "best" way to dial in amp (theoretically spoken right).

Not sure what you are referring to regarding DC. I do not use DC measurement on amps (been a while since I was in college; there is a DC component to the whole amp thing and it should not be a high value).
most if not all amps will NOT double the amp RMS in 2 ohm (1 channel) compared to 4 ohm. there will always be a "loss".
you will see a 2 ohm load draw more Current (A).

hope this helps
 
  #3  
Old 05-09-2016, 09:45 AM
slyedog's Avatar
slyedog
slyedog is offline
Supporter
Thread Starter
Join Date: Aug 2013
Location: Hawkeye state
Posts: 3,789
Received 240 Likes on 177 Posts
Default

Originally Posted by AAWAV View Post
when bridging, you do not take the channels parallel but in series.
it stacks the 2 AC signals (1000Hz test sine wave) "on top of each other", as 1 of the channel is 180 degrees reversed.
Scope is simply the "best" way to dial in amp (theoretically spoken right).

Not sure what you are referring to regarding DC. I do not use DC measurement on amps (been a while since I was in college; there is a DC component to the whole amp thing and it should not be a high value).
most if not all amps will NOT double the amp RMS in 2 ohm (1 channel) compared to 4 ohm. there will always be a "loss".
you will see a 2 ohm load draw more Current (A).

hope this helps
It does. I was attempting to say the 4 ohm bridged load will always be 2x the 2 ohm rated output. No matter what amp, bridged will always be twice the 2 ohm rated output . The whole step up DC input to AC voltage/current does get confusing. I thought the amp used AC voltage and DC current somehow on the outpit. It's been almost 20 years since I went to tech school and I switched to HVAC after few terms. Trying to regain some knowledge.
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
FLYINGBROKE
Audio Systems
23
12-09-2018 03:58 PM
Cheesehead_13
Audio Systems
11
01-20-2018 04:05 PM
ep120794
Audio Systems
17
07-01-2017 10:24 AM
tesnevo
Audio Systems
13
11-03-2016 08:11 PM
06GliderGuy
Touring Parts
9
04-02-2016 09:09 AM


Thread Tools
Search this Thread
Quick Reply: DMM gain setting


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: