Question about Sherwood RX-4105 Receiver
Can this amp drive 4 ohm spkrs
Posted on Mar 03, 2011
Sherwood RX4105 needs a air cooling system if you planning on playing loud music for 4 hours or more on loud speakers. Sherwood RX-4105 has a thermal and current sensor that will shutdown the receiver if it exceed the temperature or the current. On my Sherwood RX-4105 receiver powering my loud speaker with 12 inch woofers, I put a 120 volt AC, 9 inch, 53 watt fan on top of my receiver that is capable of blowing over 100 CFM into top ventilation holes of my receiver, I was able to crank the volume up to 50, and I had my bass control set at -8 and my treble control set +2, and my Sherwood RX4105 receiver was able to play loud music on my loud speakers for 4 hours without the receiver shutting down. I cranked the volume to 52, then receiver shutdown. I tried to crank the bass up to -6, but my receiver shutdown too. With the volume cranked up to 50, my fan kept my receiver so cool, there was very little warmth from my receiver when I put my face to the flowing air from the bottom ventilation holes of my receiver. I hooked an oscilloscope to my speakers wires of my RX4105 receiver and I hooked up my receiver to 8 ohm dummy load. I cranked the volume up to max and I viewed the wave pattern on my oscilloscope, there is distortion in the wave pattern at max volume. Distortion can blow out a tweeter in the speaker that is something you want to avoid. There highest volume I can go with my Sherwood RX4105 receiver without distortion is 55 and my receiver still put out 100 watts of power into my 8 ohm dummy load.
From my experience with transistorize power amplifiers, both RF (radio frequency) and Audio, that is capable running 100 watts or more need a air cooling system. The just a aluminum heatsink is not enough. With a 100 watt amplifier, the heatsink will not get any cooler, it will keep getting hotter and hotter until it breaks down.
Big loudspeakers draw a lot current. You need a receiver that is capable of running speakers that have an impedance of 8 ohms o less, and with a air cooling system in order to power those big loudspeakers. Sherwood RX4105 receiver is only design to run speakers with a impedance 8 ohms or more.
Posted on Jun 08, 2008
I too have the same problem with my Sherwood RX4105 receiver shutting down whenever I turn the volume up near max to my Cerwin-Vega CLS-12 speakers. I hooked a 8 ohm dummy load to my Sherwood RX4105, and then I turned the volume up to near max, it did not shutdown. I hooked a clamp on current meter on my speaker wires, and I found out that my CLS-12 speakers was drawing more current than on the 8 ohm dummy. I hooked an audio generator to my RX4105 receiver, and went through audio frequencies on my Cerwin-Vega CLS-12 speakers with my clamp on current meter, and I found out that my 12 inch woofers was drawing more current below 240 Hertz, and it had impedance less than 8 ohms. What cause the Sherwood RX4105 receiver to shutdown whenever you turn the volume up is low impedance of the speakers on certain frequencies. Speakers is not always 8 ohms throughout the audio frequencies range. They can go lower or higher than 8 ohms impedance throughout audio frequencies. Low speaker impedance on 8 ohm speakers usually occur around the woofer frequency range. My Sherwood RX4105 will not shutdown cranking the volume up if the speaker impedance 8 ohms or higher. Sherwood RX4105 will shutdown if the speaker impedance is less than 8 ohms. The low ohmage from the speakers will get the receiver hot and then eventually will shutdown. I had to turn the bass control down on the Sherwood RX4105 receiver in order to keep it from shutting down. I also tried hooking my speakers up in series to double the impedance on one audio channel on my Sherwood RX4105, and cranked volume up to near max, and my receiver did not shutdown, and it was just as loud as one speaker on one audio channel. But when I hooked just one speaker up on one audio channel, and I cranked the volume up to near max, my Sherwood RX4105 shutdown.
I am planning getting an receiver than can handle speakers with an impedance 2 to 8 ohms. Receiver that is capable of low impedance speakers delivers high current to the speakers. But I still would need an equalizer to cut back some of the audio on certain frequencies that run on low impedance because you can blow out woofer or blow out the fuse on the woofer if I crank the volume up on a high current amplifier.
Posted on Jun 05, 2008
You may be using an equalizer? try to pop-up the volume with all tone controls in flat mode. see if it still cuts off. if this is the first time youencounter this then something must be wroing with either your speakers or your amp. unless your ventilation is not good enoughg, you can also try placing a blower on top of your unit to cool it down
Posted on May 04, 2008
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