Dummy Loads: Wirewound VS Aluminum Shell? - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 4th February 2014, 02:12 AM   #1
diyAudio Member
 
Join Date: Jan 2014
Location: Central Maine
Default Dummy Loads: Wirewound VS Aluminum Shell?

Looking to build a dummy load for bench testing with no sound. Right now I am using two 12" subs in a sealed enclosure wired out of phase to cancel each other out (for the most part). But it still has quite a bit of sound and vibration at high volumes, and they just cannot handle some of the amps Ive been testing at full power (or anywhere near on some).

So I was looking at load resistors. Would like to get around 2000W of dissipation. I was going to buy 16 x 16-ohm 120W wirewound resistors. Put them in batches of 4 in parallel (so 4 sets of 4-ohm @ 480W) that I could then wire to in series/parallel together for various loads.

These are the wirewound Wirewound Power Resistor 16 Ohm 120 Watt Audio and Power Supply Load | eBay

But I also saw these aluminum shell resistors that are rated at 1000W?!?! I could get 4 x 2-ohm versions of these for the same money and have over twice the power dissipation. 1000W 2 4 8 16 Ohm Aluminium Shell Braking Resistor Resistance Dummy Load Audio | eBay

Anyone have any negatives about doing the aluminum shell vs the wirewound? Do you think these ratings are accurate? I plan on sinking them and adding fans in either scenario.
  Reply With Quote
Old 4th February 2014, 02:58 AM   #2
diyAudio Member
 
jeanious2011's Avatar
 
Join Date: Nov 2010
Location: Texas
Mouser and Digikey has a few that are around 20 bucks each and are 300watts.

Also recently saw some youtube videos about how to make your own 8ohm loads using heating elements and a little creativity.

I rather use the used wire wound that are available on ebay for pretty cheap or on mouser.
__________________
Tek 465, Fluke 111, TPI 440, AudioAuthority 2/77 Power Supply, Alpine HU for signal or Eico 379 Sine/Square Wave Generator.
  Reply With Quote
Old 4th February 2014, 01:12 PM   #3
ultra is offline ultra  Greece
diyAudio Member
 
ultra's Avatar
 
Join Date: Jun 2005
Location: Athens
These shell resistors are a class on their own.
I made the mistake to buy one.
Although it is supposed to be "silent" that means with no sound,
this resistor "whistles" your test frequency.
Additionally, the leads are way too thin to handle high current.
Attached Images
File Type: jpg 1000w 4Ω.JPG (17.9 KB, 136 views)
  Reply With Quote
Old 4th February 2014, 01:31 PM   #4
jcx is online now jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
Reliance 2,000 Watt 120 Volt Electric Water Heater Element: Other Home Improvement : Walmart.com

and you have hot water after the test
  Reply With Quote
Old 4th February 2014, 01:41 PM   #5
diyAudio Member
 
Join Date: Jan 2014
Location: Central Maine
Quote:
Originally Posted by jcx View Post
That would give you a weird impedance of like 7.2 ohms though. Ideally if I could find a 3500W 120V one I would be golden.
  Reply With Quote
Old 4th February 2014, 02:22 PM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Most or maybe all of the aluminium clad power resistors are intended to be fitted to a large heatsink to reach their dissipation specification. The need for a heatsink makes them very expensive.

I prefer using arrays of ceramic cased 5W power resistors. Banks of 4r0 are very useful for many different test/dummy loads. I have 4 off 4r0, each at 225W (45off 20r 5W in series parallel)
4+4 = 8
4+4+4 =12
4+4+4+4 = 16
4||4 = 2
4||4||4 = 1r33
4||4||4||4 = 1r0

4||4 + 4||4 = 4r0
4||4||{4+4} = 1r6
4||{4+4} = 2r67
etc.....
__________________
regards Andrew T.

Last edited by AndrewT; 4th February 2014 at 02:30 PM.
  Reply With Quote
Old 4th February 2014, 03:09 PM   #7
diyAudio Member
 
Join Date: Jan 2008
If power testing for brute force than any big dummy load such as heater is good.

If looking for distortion performance, inductive load will be massive contamination.
  Reply With Quote
Old 4th February 2014, 03:29 PM   #8
diyAudio Member
 
jeanious2011's Avatar
 
Join Date: Nov 2010
Location: Texas
Quote:
Originally Posted by ultra View Post
These shell resistors are a class on their own.
I made the mistake to buy one.
Although it is supposed to be "silent" that means with no sound,
this resistor "whistles" your test frequency.
Additionally, the leads are way too thin to handle high current.
Although when testing with the wire wound I could here higher fhz pretty good, that was without ANY hardware. Once I mounted them with proper hardware they are pretty silent.

There's a guy on youtube that compared a non inductive load with a large wire wound resistor and pretty much explain what to expect which wasn't much difference. There is like a 300 buck difference between the two, wire wound can be bought for around 25 bucks and an non inductive is around 300.00.

I would like to have a non inductive load to compare to a large wire wound resistor...to actually measure the differences for myself.
__________________
Tek 465, Fluke 111, TPI 440, AudioAuthority 2/77 Power Supply, Alpine HU for signal or Eico 379 Sine/Square Wave Generator.
  Reply With Quote
Old 4th February 2014, 04:18 PM   #9
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
non inductive is not really necessary for dummy load testing, It should be done to prove DUT reliability and insure PS & heat sink device temps. (near clipping ) which is overkill for most DIY
you can use a smaller load for square wave and frequency flatness, IMD test maybe a variable.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust

Last edited by infinia; 4th February 2014 at 04:27 PM.
  Reply With Quote
Old 4th February 2014, 05:18 PM   #10
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Quote:
Originally Posted by jeanious2011 View Post

I would like to have a non inductive load to compare to a large wire wound resistor...to actually measure the differences for myself.


would you test inductance value? then what...
what would be impacted in an Audio PA test?

IMD could be very slightly affected, but I'm pretty sure the inductance will be very low compared to any sub or woofer.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dummy Loads seankane Car Audio 24 5th November 2013 04:01 PM
Two Dayton Audio 100w dummy loads zcables Swap Meet 4 2nd September 2013 10:23 PM
Custom designed aluminum chassis shell panel processing wiredrawing sanded anodic oxi lotus03 Vendor's Bazaar 16 25th May 2011 02:17 AM
FS:PartsExpress 8 ohm 100w Dummy Loads fwaldoch Swap Meet 1 3rd August 2010 08:54 PM
Any point in putting dummy loads on unused speaker outputs on headunit? eRiCdWoNg Car Audio 2 6th May 2004 08:12 AM


New To Site? Need Help?

All times are GMT. The time now is 07:21 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2