Dummy Load for Amplifier Test

skrol
skrol Posts: 3,436
edited June 2011 in DIY, Mods & Tweaks
I am working on a Carver PM-950. It seems ok when not driven very hard. Just a slight 60Hz hum. The guy says that it starts cutting out when it gets warm. I suspect that the amp is ok and that the problem is in the mixer as it def does have some issues.

I don't want to drive it hard with any of my speakers not to mention it is too loud. Anyone have any economical ideas for making a dummy load for testing an amp?
Thanks
Stan
Stan

Main 2ch:
Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

HT:
Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

Other stuff:
Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
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Comments

  • audiobilly
    audiobilly Posts: 351
    edited June 2011
    Don't know if you are familiar with this site, but here is some good reading for ideas.

    http://www.diyaudio.com/forums/parts/35050-8-ohm-dummy-load.html
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  • BlueFox
    BlueFox Posts: 15,251
    edited June 2011
    4-8 ohm resistor at 200 watt, or more, rating?

    http://www.google.com/products/catalog?hl=en&q=8+ohm+resistor+200+watt&bav=on.2,or.r_gc.r_pw.&biw=1100&bih=835&wrapid=tlif130750627237810&um=1&ie=UTF-8&tbm=shop&cid=10695229063316396272&sa=X&ei=e_buTYrwKsuUtwet9aTqCQ&ved=0CG0Q8wIwAg#

    http://s88932719.onlinehome.us/resistors.htm
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
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    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
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  • zingo
    zingo Posts: 11,258
    edited June 2011
    I use two of these dummy loads for testing and burn-in. They work very well and are very well made. I actually ended up terminating them with banana plugs as that was easier to use. I used to solder resistors together until I had larger enough power handling, but that's a bit of work, and I would always end up loosing them; you can't loose these dummy loads as they are surprising large.

    019-020_l.jpg
    Jake
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  • skrol
    skrol Posts: 3,436
    edited June 2011
    Thanks, that is some good stuff. The PM-950 is rated 325W per channel into 8 ohms, 475W per channel into 4 ohms. I can probably take one of the heating elements out of the oven while my wife is asleep:biggrin:.

    I am starting to believe that the amp is fine. I hooked it up to my Denon DRA-825R pre-amp out and attached my S8's. The hum was gone and it really had a nice clean, rich, warm sound that i was not expecting from a Pro-Amp. Of course I was doing this at night while the family was sleeping so I couldn't really crank it enough to drive it hard.

    Dang, I just placed an order with PE yesterday. If I added a couple of these I could have gotten free shipping.
    Stan
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
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  • TNRabbit
    TNRabbit Posts: 2,168
    edited June 2011
    If you REALLY want to cook, place them in a 5 gallon bucket of water & watch it boil~
    TNRabbit
    NO Polk Audio Equipment :eek:
    Sunfire TG-IV
    Ashly 1001 Active Crossover
    Rane PEQ-15 Parametric Equalizers x 2
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    Klipsch RT-12d Subwoofer
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  • zingo
    zingo Posts: 11,258
    edited June 2011
    TNRabbit wrote: »
    If you REALLY want to cook, place them in a 5 gallon bucket of water & watch it boil~

    Or liquid nitrogen!
    Jake
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  • zingo
    zingo Posts: 11,258
    edited June 2011
    The reality is I only have the 100w dummy loads, but have pushed them over that power limit on tests by limiting the time. If you want to push 325w into a 200w dummy load for a few seconds to get a reading, it's not going to be a problem. Just use a well designed dummy load with cooling fins and you've been fine.
    Jake
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