Changing the way I test amps. And why "clamping" is flawed. - Car Audio Classifieds!
Car Audio Classifieds!  

Go Back   Car Audio Classifieds! > Car Audio Help & Discussion > Testing & Scientific Data Discussion

Testing & Scientific Data Discussion Results from Speaker and amplifier Testing


Notices

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-27-2013, 09:33 PM
TaylorFade's Avatar
SPL Retard
 
Activity Longevity
0/20 18/20
Today Posts
0/11 ssss12327
Location: Louisiana
Thanks: 265
Thanked 2,855 Times in 1,641 Posts
iTrader: (67)
Feedback Score: 67 reviews
Default Changing the way I test amps. And why "clamping" is flawed.

In the ongoing effort to provide ever increasing accuracy and legitimacy of my test results, there were two rather exciting additions to my test "bench" today.

The first isn't a big deal to you, but it's a "must have" for me in the DC voltage drop battle since I've been using a cheapo batt charger for power. Caps are fine for short bursts, but even a rather healthy number of banks starts to drop pretty low on sustained testing. And it takes my little charger forever to keep up. So... a 100A / 13.8v power supply gets to handle voltage duty now. I hope to add more powa, but holy hell these things are pricey.

This thing is my new best friend.


Second, and more importantly... I got a bank of fixed resistance. What you see here is 5,000w worth of fixed resistors with different ohm loads available depending on how I configure them.



What's the big deal, you say? Well... I'll tell you. One really awesome thing about these is that I don't have to tear up subs to test amps. Or wake the dead while doing it. But that's just a bonus.

The other thing that's cool here is the "fixed" part. As in, a purely resistive load as opposed to an inductive load (like subs). If I configure these to a 1 ohm load... that's what I get. 1 ohm. No "rise."

Now we will science...

When we measure the current and voltage on an inductive load like subs, the current and voltage are out of phase. It's just the nature of the beast. Basically what that means is that we are measuring them at different times. The further they are out of phase, the larger the difference between the "real" power and the "apparent" power.

Real power, apparent power and power factor are sort of a difficult concpet to grasp, so if you need to Google, I'll wait...

Here's a pic to illustrate what I mean. Even though the peaks are the same here... you can see the difference in the phase. Known as the "phasor angle." And actually... if you can measure or know this angle, you can calculate the real power. Fwiw, these look to be ~ 50* out of phase.



If you measured these two, you'd wind up with a false high reading of about 36%. This is why we see 1k's doing 1.5k "apparent" power.

Here's another pic. You can see in the first one that even though the current and voltage have different peaks, they're in phase. These are the same two measurements except that one is a purely resistive load and the other is an inductive load. These happen to be 90* out of phase. It's just for illustrative purposes since all this would probably do is generate heat. Lol.




Aaaaaaanyway. This all means that all of our clamps on subs are false high readings. How false? That's difficult to say for your clamps, but I can show you on an amp I tested today.

The amp in question is irrelevant, but it was setup exactly the same in both tests. The only major difference is that one test is on a sub and the other is on the resistors. The difference between the "rise" and the resistance here is pretty negligible. As is the .3 dcv difference.

Here we have the inductive test. As in... clamped on a sub. The result I got here is 789w rising to 2.3 ohms.



Now, here's the exact same amp and the exact same settings- except on the resistors wired to 2.5 ohms. Result... 542w @ 2.7 ohms. (note: the "rise" from 2.5 to 2.7 is due to the inaccuracy of this type of current clamp.)




Holy hell I can get long winded.

So, this amp is doing 789w "apparent" power, but it's really only doing 542w "real" power. You guys following me here?

This is the concept behind the AD-1 amp dyno. And why they are all high and mighty about it being the only "real" results and being superior to "clamping" blah blah blah. And technically... they're right. BUT.... since clamping on subs is the end user industry standard across the board, I will continue to include apparent power clamps in my results. Only now, I have another data point to include in my testing.

tl;dr. I haz meters and stuff. Suck it.
__________________
4x world champ
4x world record holder

Quote:
Welcome to the world of SPL.

Where nothing makes any fucking sense.
Quote:
Music and movies are art. Audio is a science.
- Floyd E. Toole

Last edited by TaylorFade; 03-30-2014 at 03:24 AM.
Reply With Quote Quick reply to this message
The Following 16 Users Say Thank You to TaylorFade For This Useful Post:
666WMD (08-27-2013), Aero_d2 (08-27-2013), AlwaysLearning (08-28-2013), AudiophilesEngineering (11-15-2013), blackfive (01-31-2015), BlackWaterOp (11-03-2013), brandon_s0854 (09-05-2013), CLRagland1 (11-30-2013), dirt101 (08-27-2013), iamsonic (08-27-2013), jheist1991 (08-27-2013), kn0wledge000 (01-21-2014), momofx (09-17-2013), naughtyca (08-28-2013), nkrell11 (09-05-2013), TeamPSI (09-09-2013)
Sponsored Links
Advertisement
 
  #2  
Old 08-27-2013, 09:40 PM
korey_hofer's Avatar
Elite Member
 
Activity Longevity
0/20 20/20
Today Posts
0/11 ssss33855
Location: willy wonka's sex dungeon
Thanks: 10
Thanked 965 Times in 748 Posts
iTrader: (11)
Feedback Score: 11 reviews
Default

I always wondered why people now days use subs instead of resistors to test amps. Back in the 90's it was the other way around.
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
  #3  
Old 08-27-2013, 09:41 PM
Jeffhulbert50's Avatar
Authorized Vendor
 
Activity Longevity
0/20 14/20
Today Posts
0/11 ssss14115
Location: middle of east
Thanks: 65
Thanked 1,756 Times in 1,344 Posts
iTrader: (83)
Feedback Score: 83 reviews
Default

I likes the load bank... would clamping follow more along dynamic power ranges and fixed load be more "tru" continuous rms
Reply With Quote Quick reply to this message
 
  #4  
Old 08-27-2013, 09:43 PM
dirt101's Avatar
Elite Member
 
Activity Longevity
0/20 17/20
Today Posts
0/11 ssssss956
Location: VA
Thanks: 42
Thanked 56 Times in 44 Posts
iTrader: (16)
Feedback Score: 16 reviews
Default

Love it, what will be the power "cap" with this setup?
Reply With Quote Quick reply to this message
  #5  
Old 08-27-2013, 09:44 PM
Turn it up's Avatar
Elite Member
 
Activity Longevity
0/20 14/20
Today Posts
0/11 sssss1933
Location: DUB C
Thanks: 17
Thanked 97 Times in 79 Posts
iTrader: (0)
Feedback Score: 0 reviews
Default

Good stuff!
__________________
Quote:
Jacob=making dreams a reality lol

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
  #6  
Old 08-27-2013, 09:44 PM
HiloDB1's Avatar
CACO Supporter
 
Activity Longevity
0/20 19/20
Today Posts
0/11 sssss3158
Location: Hawaii
Thanks: 12
Thanked 114 Times in 93 Posts
iTrader: (13)
Feedback Score: 13 reviews
Default

This is also how most amp manufacturers produce those nice birth sheets you get with your amp. They use a fixed resistance instead of a reactive load.
__________________
Quote:
Id say, that because I clip so much, my opinion no longer matters on this site.
Reply With Quote Quick reply to this message
  #7  
Old 08-27-2013, 09:46 PM
goatskindreams's Avatar
Do you even demo?
 
Activity Longevity
0/20 17/20
Today Posts
0/11 sssss1797
Location: West Monroe NY
Thanks: 196
Thanked 138 Times in 109 Posts
iTrader: (16)
Feedback Score: 16 reviews
Default

Power supplys are a big investment. Cb radio base stations are just as addictive as car audio. People spend stupid money on there set-ups
Reply With Quote Quick reply to this message
  #8  
Old 08-27-2013, 09:48 PM
TaylorFade's Avatar
SPL Retard
 
Activity Longevity
0/20 18/20
Today Posts
0/11 ssss12327
Location: Louisiana
Thanks: 265
Thanked 2,855 Times in 1,641 Posts
iTrader: (67)
Feedback Score: 67 reviews
Default

Quote:
Originally Posted by Jeffhulbert50 View Post
I likes the load bank... would clamping follow more along dynamic power ranges and fixed load be more "tru" continuous rms
I suppose we can look at it that way. but I hesitate to use that terminology. "Max" or "Dynamic" power when including it. I'll come up with something more generic for those who didn't happen to read this.

Quote:
Originally Posted by dirt101 View Post
Love it, what will be the power "cap" with this setup?
Well... the bank is rated for 5k continuous, but I'm curious to see if they can handle more in bursts.

Quote:
Originally Posted by HiloDB1 View Post
This is also how most amp manufacturers produce those nice birth sheets you get with your amp. They use a fixed resistance instead of a reactive load.
And they have much, much, much more expensive "meters" than I do. Lol.

I'm working on it!!
__________________
4x world champ
4x world record holder

Quote:
Welcome to the world of SPL.

Where nothing makes any fucking sense.
Quote:
Music and movies are art. Audio is a science.
- Floyd E. Toole
Reply With Quote Quick reply to this message
  #9  
Old 08-27-2013, 09:49 PM
Car audio classifieds, stereo sales, subwoofer amps mids classified caraudio, BANNED!!
 
Activity Longevity
0/20 15/20
Today Posts
0/11 sssss2429
Location: Wisconsin/Minnesota border
Thanks: 2
Thanked 266 Times in 211 Posts
iTrader: (46)
Feedback Score: 46 reviews
Default

Will be some sad people when they find out actual power of their amp is low! lol

Sent from my DROID RAZR using Tapatalk 4
Reply With Quote Quick reply to this message
The Following User Says Thank You to brandes.cm For This Useful Post:
  #10  
Old 08-27-2013, 09:51 PM
djscrubb's Avatar
Captain $hit disturber
 
Activity Longevity
0/20 17/20
Today Posts
0/11 sssss2332
Location: Pembina ND
Thanks: 232
Thanked 221 Times in 196 Posts
iTrader: (20)
Feedback Score: 20 reviews
Default

nice man!!!!
__________________
Quote:
Sometimes I just want to drive my shit into a shop and hand them a fistful of money and be like... "Here. Do this shit."
I have zero problems with people having a shop or other enthusiast do their build. But it's a little disrespectful they take credit for it and/or don't correct people when they assume the owner did the work. Happens all the time.
4 zv4 18:2 ct7k: c pillar wall(not sealed off)156.11:
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Car Audio Classifieds! forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Location
Where you live
Level of Car Audio Knowledge
What's your level of car audio?

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
clamping strapped amps? jdmferio13 General Car Audio Discussion & Questions 7 07-25-2013 07:12 AM
Nightshade v.3 15" Free Air Test -- Formerly "Monster v.2 Prototype" sundownz (Sundown Audio) 100 02-16-2013 04:01 AM
Clamping strapped Amps Staralpha1 General Car Audio Discussion & Questions 1 10-09-2010 10:47 PM
changing amps nuboot Team Teamless 9 06-02-2010 03:18 AM
Thinking about changing amps? teamsubgopoof General Car Audio Discussion & Questions 4 02-07-2009 07:12 PM

» Amps
A/d/s/
Advent
Alphasonik
Alpine
American Bass
ARC Audio
Atomic
Audio Art
Audio Gods
Audiobahn
Audiocontrol
Audiopipe
Audison
Aura
Autotek
Avionixx
Bazooka
Beyma
Blaupunkt
Boss
Boston Acoustics
Bravox
Cadence
Cascade (CAE)
CDT Audio
Cerwin Vega
Clarion
Clif Designs
Concept
Coustic
Critical Mass
Crossfire
Crunch
DB Drive
DC Audio
DC Power
DEI
Denon
Diabolo
Diamond
Digital Designs
Directed
DLS
Dual
DYnamat
Dynaudio
Earthquake
Eclipse
Elemental Designs
ESX
Eton
Farenheit
Fi Car Audio
Fix My Speaker
Focal
Fusion
Genesis
Ground Zero
Hafler
Helix
Hertz
Hifonics
Hushmat
Image Dynamics
Infinity
Interfire
JBL
Jensen
JL Audio
JVC
Kenwood
Kicker
Knu Konceptz
Kole Audio
Kove Audio
Lanzar
Lightning Audio
Linear Power
MA Audio
Magnat
Marantz
Massive Audio
MB Quart
McIntosh
Memphis
Metra
MMATS
Mobile Authority
Morel
MTX
Nakamichi
Niche Audio
O2 Audio
Ohio Generator
Optima
Orion
Oxygen Audio
OZ Audio
PG Audio
Phase Linear
Phoenix Gold
Pioneer
Polk
Power Acoustik
Powerbass
Powermaster
Precision Power
Profile
Pyle
Pyramid
RadioShack
Rainbow
Rampage
RE AUdio
Rockford Fosgate
Scanspeak
Scosche
Seas
Sony
soundstream
Sparkomatic
SPL Dynamics
Stinger
Sundown Audio
Swiss Audio
Targa
TC Sounds
TREO Engineering
TRU
Tsunami
Ultimate
US Acoustics
US Amps
Velodyne
Vifa
Viper
Visonik
Xtant
Zapco
Zed Audio
Powered by vBadvanced CMPS v3.2.3
Links
Amp Guts
amplifier, amp guts, ampguts, car audio classifieds, speakers and subs for sale with listings of 12 volt sound systems. Security systems for sale for aftermarket car audio equipment with amplifier and amps for sale
Car Audio Forum
car audio forum, moble audio, car stereo, wholesale car audio, 12 volt, with, amplifier, amp, subwoofer, sound quality, buy car audio, and sell automotive stereo systems for cars
Car Audio Sound Quality Forum
Sound QUality science based car audio forum, amplifier, subs and speaker design, fabrication help, sound systems forum, aftermarket car audio website for sound quality.
Car Stereo Forum
DIYMA car audio stereo forum for 12 volt car audio subwoofer and amplifier systems that have sound quality with wholesale car audio products.


All times are GMT -5. The time now is 05:24 AM.


Powered by vBulletin
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.6.0
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.