EZLoad Dummy Load - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 19th January 2013, 07:19 PM   #1
SandyG is offline SandyG  United States
diyAudio Member
 
SandyG's Avatar
 
Join Date: Jul 2011
Location: Los Angeles
Default EZLoad Dummy Load

Working on some of the amps that I have recently built and working on the next version of one that is higher power I figured I better start beefing up my dummy load for the amps. My 4 soldered together 20w 2ohm resistors would not be adequate for the next amp so figured time to take a break and work on test equipment.

I picked up 5 200w 4ohm resistors from EPay and fabricated a simple way to have a flexible very high powered load for testing. Bringing out each 4ohm resistor to binding posts I could have a bunch of combinations to test with, i.e., stereo 8ohms at 400w per channel, etc. I do guess the ratings for these large resistors are when dipped in liquid nitrogen, but even derating 50% plenty of head room for any amp I'm going to build and will not have to worry about things getting too hot or the messy tangle of soldered up resistors.

I also found a small fan in the junk pile and figured I would add that too just for fun.

Cabinet was an aluminum hammond 6"x10"x2" primed and painted. Other aluminum was scrap in the garage.
Attached Images
File Type: jpg IMAG1638.jpg (128.1 KB, 242 views)
File Type: jpg IMAG1640.jpg (139.9 KB, 234 views)
File Type: jpg IMAG1642.jpg (85.6 KB, 231 views)
File Type: jpg IMAG1644.jpg (146.1 KB, 229 views)
File Type: jpg IMAG1645.jpg (142.7 KB, 228 views)
File Type: jpg IMAG1647.jpg (179.2 KB, 98 views)
File Type: jpg IMAG1670.jpg (134.3 KB, 99 views)
File Type: jpg IMAG1671.jpg (138.5 KB, 101 views)
File Type: jpg IMAG1673.jpg (200.6 KB, 95 views)
  Reply With Quote
Old 19th January 2013, 07:57 PM   #2
Matt BH is offline Matt BH  United Kingdom
diyAudio Member
 
Join Date: Jul 2009
Location: Cheltenham
Hey Sandy, nice job. I use six 12R 100W wirewounds on a heatsink. Don't worry too much about de-rating unless you plan to run them at full power for long. These type of resistors don't mind being overloaded for a short time. I have tested an 800W RMS per channel amp flat out into mine, they got toastie but no problems. Could you give a link to those resistors? I have not seen any so long. The 200W types I have seen are short and fat.

Cheers Matt.
  Reply With Quote
Old 20th January 2013, 12:38 AM   #3
SandyG is offline SandyG  United States
diyAudio Member
 
SandyG's Avatar
 
Join Date: Jul 2011
Location: Los Angeles
Thanks Matt -

I would expect they should be ok for the 100-150w amp that is coming up. Figured do it over the top and not have to do it again

Here is the link the the EBay seller. I had him do 4 4ohm and 1 8ohm at the same price. So I have one more 8ohm 200watt, might make a smaller one shot for that.

5pcs 4 Ohm 4R 200W Watt Power Metal Shell Case Wirewound Resistor | eBay

He has them in 2 ohm, 8 ohm as well and same in the 100watt size which are a bit more economical. He shipped them very quick as well.

Sandy
  Reply With Quote
Old 22nd January 2013, 09:52 PM   #4
diyAudio Member
 
Join Date: Nov 2002
Since you showed yours I will show mine. Made from all scrap parts with the exception of some high power resistors purchased at scrap prices.

http://www.ebgusa.com/NEWPDF/EBGCAT33.pdf


Mine uses 600 watt 4 ohm resistors in a series parallel config and gives me 2) large 4 ohm loads for testing or I can jump the binding post for one large 8 ohm load.

I used a JBL heat sink to mount the resistors to and a fan assembly from a commercial rack that uses 3) 55cfm fans to cool the heat sink.
Attached Images
File Type: jpg P1220001.jpg (115.3 KB, 80 views)
File Type: jpg P1220004.jpg (113.1 KB, 71 views)
File Type: jpg P1220005.jpg (129.3 KB, 40 views)
File Type: jpg P1220006.jpg (132.5 KB, 34 views)
File Type: jpg P1220007.jpg (137.4 KB, 33 views)
File Type: jpg P1220008.jpg (111.1 KB, 41 views)

Last edited by Original Burnedfingers; 22nd January 2013 at 10:02 PM.
  Reply With Quote
Old 22nd January 2013, 10:06 PM   #5
Loren42 is offline Loren42  United States
diyAudio Member
 
Join Date: Sep 2008
Location: "Space Coast" Florida, USA
My favorite is submerging the resistors in a closed paint can filled with mineral oil.

You need a pinhole for air to escape, but the load will take much more power than dry resistors, even when mounted to a heat sink.
  Reply With Quote
Old 22nd January 2013, 11:25 PM   #6
SandyG is offline SandyG  United States
diyAudio Member
 
SandyG's Avatar
 
Join Date: Jul 2011
Location: Los Angeles
Burnedfingers - I like your way of thinking!

Loren42 - I thought about doing something similar like the old dummy load from some of my old ham gear the 'Cantenna' which was something like that, then I though of the mess of the oil when I drop the can on the floor or something to that effect

Might come in handy as a room heater at some point, this winter was cold!

Sandy
  Reply With Quote
Old 22nd January 2013, 11:35 PM   #7
mike567 is offline mike567  United States
diyAudio Member
 
Join Date: May 2011
Location: florida west coast
A lot of money being spent on simple resistor. Most dummy loads are temporary... why not use an old heater modified for the desired load. Old heating element from central a/c unit will sink thousands of watts. (5 KW element on old heater frame will sink 1000 watts with out fan. It will get HOT but wont melt.
  Reply With Quote
Old 22nd January 2013, 11:50 PM   #8
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
There's no need for a big heatsink, just put the resistor in a bucket of water. That'll be your 1000W resistor. The water does not significantly change the resistance, it should not at all if it is clean.
  Reply With Quote
Old 23rd January 2013, 09:37 PM   #9
diyAudio Member
 
Join Date: Nov 2002
Quote:
Originally Posted by SandyG View Post
Burnedfingers - I like your way of thinking!

Loren42 - I thought about doing something similar like the old dummy load from some of my old ham gear the 'Cantenna' which was something like that, then I though of the mess of the oil when I drop the can on the floor or something to that effect

Might come in handy as a room heater at some point, this winter was cold!

Sandy
Thanks, I bought the resistors for $4 ea. Since I use it all the time I needed something that was large enough to load a very high output amplifier on.
  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
Power load, dummy load (pic) luka Power Supplies 43 9th February 2012 02:50 PM
Dummy Load NickParr666 Car Audio 7 10th September 2011 03:58 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 on ebay Bill Fitzpatrick Parts 0 10th September 2004 05:42 PM


New To Site? Need Help?

All times are GMT. The time now is 05:22 PM.


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