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RF-7 ii blew up my receiver?


quakana
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the receiver powers up,but then displays "protecting" for a few seconds then power down...fuse is same value (fast blow 6.3 amp) and is still working

 

 

Quakana,

 

I really believe your Sony just does not have the gusto to handle the RF-7II's low impedence dips. It looks like the protection circuitry is very sensitive and easily senses a load the Sony just does not like. I had a wonderful 80's Denon POA-1500 2-channel amp that was rated conservatively at 150w/ch into 8 ohms that would drive my fortes all day long at ear bleeding levels. But when I hooked my RF-63's up to the Denon and twisted the volume knob a bit on the preamp, after about 15 minutes the Denon's protection circuitry kicked in and never came out.

 

Off to the repair shop the Denon went and when I got it back, it stayed far away from the RF-63's. I later learned that even though the Denon POA-1500 was a well regarded amplifier, it was never built to handle sustained(high volume) sub 8ohm loads.

 

Bill

Edited by willland
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OK.....hooked up an old...and I mean old...Yamaha RX-V690 and it is doing leaps and bounds above what the sony was doing before it died. Tomorrow I shall smash the dead Sony with my log splitter and shop for a real AMP.....thanks for all your help and I cant believe these speakers melted this POS ...BTW ......these things are Massive.... Huge!!!!! Maybe another set is in order hee hee

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the receiver powers up,but then displays "protecting" for a few seconds then power down...fuse is same value (fast blow 6.3 amp) and is still working

Quakana,

I really believe your Sony just does not have the gusto to handle the RF-7II's low impedence dips. It looks like the protection circuitry is very sensitive and easily senses a load the Sony just does not like. I had a wonderful 80's Denon POA-1500 2-channel amp that was rated conservatively at 150w/ch into 8 ohms that would drive my fortes all day long at ear bleeding levels. But when I hooked my RF-63's up to the Denon and twisted the volume knob a bit on the preamp, after about 5 minutes the Denon's protection circuitry kicked in and never came out.

Off to the repair shop the Denon went and when I got it back, it stayed far away from the RF-63's. I later learned that even though the Denon POA-1500 was a well regarded amplifier, it was never built to handle sustained(high volume) sub 8ohm loads.

Bill

I must set my Harman Kardon ss citation to 4 ohm when playing thru fortes. they have 4 ohm woofers and will make my amps run hot if set to 8 ohm.

Edited by UH1dg337
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I agree with Willand. All the specs on the receiver list 8 ohms in the manual. I don't see in the manual any listing for switching to a 4 ohm speaker.

The specs for the RF7ii say 8 ohm compatible but I don't put much faith in that. My guess is that the impedance dips to 4 ohms or less, as many Klipsch speakers do, and this causes problems with some amps. It is really a shame that Klipsch makes a statement like this.

BTW, when I purchased my Forte II I went to the Sony store on Michigan Avenue and saw that a Sony mini-system had shoe box speakers marked 4 ohms. So I bought that and there are no problems with the Forte II 's. I have not measured the impedance of the Forte II but its little brother Quartet dips below 4 ohms.

You might want to measure the resistance across the input terminals of the speakers with an ohm meter (multimeter). It is true that this will only report the d.c. resistance or zero Hertz impedance. The actual impedance of speakers vary with frequency. Nonetheless, the impedance of the woofer circuit very often dips to a value which is equivalent to that measured value, and is, in fact, a pure resistance there. At least you'll know something.

Regarding the amp. Disconnect the speakers and test the amp with headphones. If that doesn't give some sound in headphones -- I see in the manual there is a reset procedure. There is some chance that the amp is stuck in protected mode. Others here have reported home theater systems coming back to life with a reset.

If the amp is actually working: You might put a 4 ohm power resistor in series with the speaker feed. It will probably affect the response but the amps equalizer could solve this. Another would be to improvise an autotransformer with an RS line transformer. I can tell you more if you're interested.

Best,

WMcD

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Maybe the RF-7ii is a bit too much load for that AV receiver. I'll I can find is that the Sony puts out 110 watts into 8 ohms.

I (think) the RF-7ii dips below 8 ohms at lower frequencies.

Did the AV receiver seem hot after it shutdown?

Can you try a different receiver, amp or integrated amp with RF-7iis?

Yeah, the RF7-II actually dips to 3.9 ohm @ 160Hz. So altough the Klipsch are rated as "high efficiency" speaker don't underestimate the stress they can put on your amp...

The RF7-II operates below 8 ohm between about 80Hz up to ... 600Hz. So playing dance-music at high levels does stress the amp !

See the black graph for impedance...

Klipsch_RF7_II_Impedence_Curve.jpg

Edited by jvanhambelgium
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