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Post subject: Need some tips on making a Dummy Load?
Posted: Thu Feb 06, 2014 8:32 am
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Aspiring Musician
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Joined: Wed Jan 19, 2011 6:25 pm
Posts: 432
I would like to make a dummy load for amp repair. I was looking for some help or tips. Thanks


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Post subject: Re: Need some tips on making a Dummy Load?
Posted: Thu Feb 06, 2014 9:57 am
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Rock Star
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Joined: Sat Jul 03, 2010 2:18 pm
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I use a 50-watt wire-wound 10-ohm resistor. I use an old Ohmite brown ceramic wire-wound type. New Ohmite or Dale ww resistors are very good for this function.


http://www.ttiinc.com/page/search_resul ... 1601248_61

http://www.ttiinc.com/page/search_resul ... 8657404_93


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Post subject: Re: Need some tips on making a Dummy Load?
Posted: Fri Feb 07, 2014 7:47 am
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Aspiring Musician
Aspiring Musician

Joined: Wed Jan 19, 2011 6:25 pm
Posts: 432
Thanks I cant get your link to work? How did you make yours?


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Post subject: Re: Need some tips on making a Dummy Load?
Posted: Fri Feb 07, 2014 8:06 am
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Rock Star
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How about this one?

http://www.galco.com/buy/Ohmite/850F10R


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Post subject: Re: Need some tips on making a Dummy Load?
Posted: Tue Feb 18, 2014 4:51 am
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Hobbyist
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Joined: Sun Nov 03, 2013 5:07 pm
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Not really any such thing as "Overkill" on this.
50W is not enough I work on amps up to 300W
SO I have to have bigger resistors for this, those usually end up using the speaker cabs
I would opt for at least 200W wire wounds.
Mouser has Ohmite 4 Ohm 100W wirewounds
http://www.mouser.com/Ohmite/Passive-Components/Resistors/Wirewound-Resistors/_/N-7fx9f?P=1z0zldmZ1z0x70qZ1z0wo9p

Two 100W 4 Ohm resistors can be 8 ohm or 2 ohm or 4 ohm, with 200W power dissipation

I would prefer the 8 Ohm with higher power handling.
http://www.mouser.com/Passive-Components/Resistors/Wirewound-Resistors/Wirewound-Resistors-Chassis-Mount/_/N-7fx9g?P=1z0x70h
You can use a switch or multiple jacks or Jumpers to run 4, 8, 16 Ohm up to 600W
These things dissipate by turning electrical energy into heat so the higher the power handling the cooler it will run...
You can make a nice Aluminum Chassis for it or just bolt them to a board...

Use some Brass Studs or Binding Posts with nuts and 12 or 10AWG Jumpers with ring terminals I would opt for 200W or 300W resistors personally.
Parallel you get 4 ohms
Series you get 16 ohms
single you get 8 ohms

OR if you never work on anything over 300W (really about 250W) you could get a SINGLE 16 Ohm Variable Resistor,
http://www.mouser.com/ProductDetail/Vishay-Dale/18-136-16AR/?qs=sGAEpiMZZMtbXrIkmrvidHpmKhXFqTS0xHM4QVRuDdA%3d
you can adjust from 2 ohms to 16 ohms just connect a Switchcraft 1/4" TS Jack the Sleeve to the resistor, the Tip to the Ring, then you can connect a DMM and adjust your resistor for your load, then plug in the speaker cable and off you go. You COULD add a pair of Banana Jacks so you could monitor output voltage with a DMM, and a BNC Jack so you could connect an O-Scope...
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