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

Power load, dummy load (pic)
Power load, dummy load (pic)
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
Thread Tools Search this Thread
Old 4th August 2007, 03:33 PM   #21
stoN_Cold is offline stoN_Cold  Serbia
diyAudio Member
stoN_Cold's Avatar
Join Date: Mar 2004
Location: Belgrade RS
Default Hi Luka!

First I am working with amplifiers over 30 years .This dummy load is not expensive for me , because i think very pro.I fired up 2 amps. into 4ohm, about 1h or more, never demaged any amp.This is good thing for cold winter nights
Red thing is PVC plate (insulator), & with jumpers I, manage 4, 8, 2ohm.

regards zeoN_Rider
  Reply With Quote
Old 4th August 2007, 03:50 PM   #22
luka is offline luka  Slovenia
diyAudio Member
luka's Avatar
Join Date: Sep 2005
Location: in Slovenia :)
Power load, dummy load (pic)

This is what I have. It is 5x about 66ohme, 800w each power resistors that will be in wind tunnel, air pushed by 120mm/230Vac fan, one in pic is same size, but 12Vdc. I will be able to wire them any way I will need them to be. I need top and bottom plate one with hole for fan and connectors all on one side.

Click the image to open in full size.

Click the image to open in full size.
home page @ http://www.classdaudio.tk/ @ 24/7 all year long
  Reply With Quote
Old 6th August 2007, 04:06 AM   #23
gmphadte is offline gmphadte  India
diyAudio Member
Join Date: Jul 2003
Location: Dona paula, Goa
X-rays were used to fit shoes once.
Asbestos was used in brake discs once.
Mercury was used to "cure" syphilis once.

... and Chlorine was used to kill enemy troops once.
Formaldehyde is still preserving the meat in the supermarkets.

Eat meat and live long

Gajanan Phadte
  Reply With Quote
Old 6th August 2007, 05:14 AM   #24
mzzj is offline mzzj  Finland
diyAudio Member
Join Date: Jul 2005
Location: 65N 25E
Originally posted by luka

Hi mzzj

I was thinking about resistors at first. But one 5w resistor costs 0.38€ here and you need a lot of them

OK, I get my resistors much cheaper from local surplus sales.
More likely something like 5euros/1000pcs.
Selection of resistance values is usually limited but there is always some sort of series/parallei combination that works for me.

If you are tight on budget look for toasters, washing machines, oven elements and so on whatever you can find in scrap piles.
Sauna stove elements are especially easy to find(at least here in Finland) and can take some serious loading.
  Reply With Quote
Old 8th August 2007, 03:12 PM   #25
dutch diy is offline dutch diy  Netherlands
diyAudio Member
dutch diy's Avatar
Join Date: May 2001
Location: NL, The Hague
Send a message via ICQ to dutch diy
altough a bit late,

I used 2 * 2 halogen light bulbs 12 v 50W in series setup to load-test power supplies for my class A amp. (which should deliver + and - 27 V @ a 3 A)

Fairly cheap and basically a . No need for a fan, only a pair of shades is needed .

Easy to extend to higher voltages and (by paralleling) to higher currents.
J-amp powers Avantgarde-Acoustic Trio
  Reply With Quote
Old 8th August 2007, 04:35 PM   #26
Danko is offline Danko  Hungary
diyAudio Member
Join Date: Apr 2004
Location: Hungary
A note about using bulbs: The cold resistance of the filament is about 1/10 of the warm resistance of the filament. So, if you connect a cold bulb to the PSU, the bulb draws about 10 times more current, while it's not fully warm.
Best regards, Danko
  Reply With Quote
Old 9th August 2007, 03:51 PM   #27
AndrewT is offline AndrewT  Scotland
Join Date: Jul 2004
Location: Scottish Borders
Originally posted by djQUAN
I figured if the amp would survive bench testing on 3.7ohm loads then it will do 4ohm easy. besides, resistance goes up when they start heating up.
an amp rated to operate into a 4ohm speaker is much more highly stressed than a 2r0 test load.
Even 3r7 is not as severe as 8ohm reactive to 60degree phase angle.

I usually check the 10degree phase angle load at HALF the lowest value of operating speaker load.
i.e 4ohm 10degree and 8ohm 60 degree for an 8ohm capable amplifier.
The 4ohm test can then be run safely for the two or at most three seconds it takes to gather the test data before switching the input/output voltages back to -20db. And then letting it cool.
This allows setting up at 1% power levels and flick the switch to 0db to check output voltage or check scope display and switch back to -20db to make further adjustments. One can see clip developing as the smoothing caps discharge in half second or so.
regards Andrew T.
  Reply With Quote
Old 1st September 2007, 04:11 AM   #28
draynes is offline draynes  United States
diyAudio Member
Join Date: Sep 2007
Here's a "transistance" electronic load that's infinitely variable. It can be jazzed up with voltage and current meters, a cooling fan, etc.

Attached Images
File Type: jpg psu6.jpg (24.0 KB, 561 views)
  Reply With Quote
Old 1st September 2007, 08:12 PM   #29
anatech is offline anatech  Canada
diyAudio Moderator
anatech's Avatar
Join Date: Jun 2004
Location: Georgetown, On
Power load, dummy load (pic)
Hi draynes,
I don't think those electronic loads would appreciate an AC source like an amplifier.

HP made some really nice loads, other brands as well. Nicely metered for voltage and current. DC loads only though!

"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote
Old 1st September 2007, 08:56 PM   #30
draynes is offline draynes  United States
diyAudio Member
Join Date: Sep 2007
Okay, I thought the subject was power supply dummy loads. Duh.

Anyway, I built my own audio dummy load with a large number of 24 ohm 30 watt resistors I got from a surplus dealer. I series/paralleled dozens of them with a rotary switch to give me 4, 8, and 16 ohm loads for each channel, and added a bridge rectifier and scaling resistors for power meters on each channel. It's not pretty, but it works.

In an earlier life I used to work on 75-100 watt amps on an almost daily basis - electronic sirens - and got real workout replacing burned and melted parts. Curse the invention of the 30 amp fuse!
  Reply With Quote


Power load, dummy load (pic)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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
8 ohm dummy load andrewe1 Parts 43 9th May 2011 05:44 AM
Tri Dummy Load raudio1969 Parts 0 25th February 2009 01:14 AM
dummy load reddish75 Solid State 72 3rd April 2008 01:15 AM
Dummy - load JensRasmussen Solid State 24 23rd February 2007 01:04 PM
Dummy Load resistors JOE DIRT® Parts 6 4th June 2003 02:15 PM

New To Site? Need Help?

All times are GMT. The time now is 02:32 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio