Sherwood RX-4105 2 Channels Receiver
(7 Epinions reviews)
Epinions Product Rating:
It's a great performing receiver for $94
Dec 20, 2009 (Updated Apr 12, 2010)
Review by tank9999
Rated a Very Helpful Review
This Sherwood RX-4105 receiver is the greatest performing receiver for the low cost.
Recommend this product?
If you buy this receiver, make sure your 8 ohm speaker's lowest actual impedance does not go no lower than 6 ohms throughout the audio frequency spectrum from 20 to 20,000 Hertz, otherwise, the Sherwood receiver will go into protection mode and shutdown as soon as the volume is cranked up above 40 with the bass and treble control set at 0db, or Tone Direct. If you can crank up the volume up to 56 with the bass and treble control set at 0db, or Tone Direct on your Sherwood receiver into your speakers without the receiver shutting down, don't worry about it, the speakers are OK. But if your receiver shuts down, and if you don't know your 8 ohms speaker's lowest actual impedance, have a reputable qualified technician to check your speaker's lowest impedance, and it can be corrected internally or externally if the speaker's lowest impedance is below 6 ohms.
That's what happen with my Sherwood receiver hooked up to my speakers. My Sherwood receiver kept shutting down as soon as I cranked up the volume control pass 40 into my speakers that have 12inch woofer, 6.5inch cone mid-range waveguided, and a 1 inch dome tweeter waveguided, and my speakers are rated at 300 watt peak or 150 watt rms. I hooked my receiver up to a 8 ohm speaker dummy load, and then I crank up the volume to 56 with the bass and treble control set at 0db or Tone Direct, and my receiver didn't shut down. I bought some test equipment to thoroughly check out my 8 ohm speaker's lowest actual impedance, and I found out my 8 ohm speaker's lowest actual impedance is 2.8 ohms in which that what caused my Sherwood receiver to go into protection mode and shutdown.
So I had to order some speaker crossover parts in order to build me some external speaker impedance compensation networks in order to raise my 8 ohm speaker's actual lowest impedance above 6 ohms, and provide better sound equalization. And now, I can crank up the volume on my Sherwood receiver up to 56 with the bass and treble control set at 0db, or Tone Direct with 110 watts per channel of audio output into my pair of speakers, and pounding my 9ft by 13ft room with 128decibels of sound pressure level (SPL) for 6 continuous hours, and after 6 hours, my Sherwood never did shutdown. 128 decibels sound level in a 9ft by 13ft room is an equivalent of being in an 8,000 square foot nightclub with a 20,000 watt sound system, and that is so loud that made my ears sore with those spongy earplugs on.
If you're speaker wires are over 10 foot long between your Sherwood receiver and your speakers, use 12 gauge speaker wires with that Sherwood receiver, or else, you could loose as much as 3 decibels of sound levels, and lose some high frequency response above 10,000 Hertz, and that's what I'm running now, 12gauge speaker wires. Also I had to put a 10inch 55watt 120volt AC fan on top of my Sherwood receiver blowing into the vent holes in order to keep my receiver cool, and it would extend the life of the receiver's audio output transistors while the volume control is cranked up at 56 for 6 continuous hours. Without a cooling system on top of that Sherwood receiver with the volume control cranked up to 56, the audio power output transistor's heatsink temperature inside of the receiver can climb as high as 150 degrees F or 65.56 degrees Celsius, and that is too hot to touch, and the audio power output transistors will fail. The maximum internal temperature of the Sherwood receiver's audio output power transistors is 302 degrees F or 150 degrees Celcius, and if it exceeds that, those transistors would fail. But with that 10inch fan blowing into the vent holes of the receiver will keep the heatsink temperature under 100 degrees F or 37.78 degrees Celsius.
When I monitored my Sherwood receiver's audio output on the oscilloscope, the receiver's output audio waveform is very clean and not distorted from 20 to 20000 Hertz with the volume control set at 56 with the audio generator hooked up into the line level inputs with 0.37 volt AC rms into the line level inputs, and the audio output reproduce the same waveform as the audio input, and that's linearity. On FM radio mode with music, the receiver's audio output waveform is clean and not distorted with the volume control set at 56 or less. If the volume control is set beyond 56 on FM radio mode with music, the audio output would become distorted with flattop clipping waveform in which that would overload the receiver, and the receiver will go into protection mode and shutdown.
After I did all of that, my Sherwood RX-4105 receiver performs greatly without any problems.
The following test equipment were used to test my Sherwood receiver's and speaker's performance:
(1) BK Precision 2190B 100 MHz Dual Trace Oscilloscope, and 2 0.1 ohm @ 10 watt noninductive resistor for speaker current sensing,
To measure speaker voltage, and speaker current, speaker impedance, and audio power output, and check for distortion or clipping at high volume level, and check for speaker's acoustic and electrical phase.
(2) Lodestar AD-2601A 10 Hertz to 1 Megahertz Audio Generator,
to inject audio signal into the receiver's line level input.
(3) EZ Digital FC-7150 1.5 Gigahertz Frequency counter with a 10 Megahertz time base TCO.
To check audio frequency.
(4) Velleman DVM890F Digital Multimeter with 1800 degree temperature sensor,
To measure heatsink and transistor case temperature, and audio output power supply voltage.
(5) Galaxy Audio Checkmate CM-140 30 to 8000 Hertz sound pressure level meter,
To check sound pressure levels (SPL), and speaker sensitivity in db(SPL) / 2.83volts / Meter.
(6) Behringer ECM8000 15 to 20,000 Hertz measurement microphone,
To check speaker's frequency response, and to sense speaker's acoustic waves in order to check the speaker's acoustic phase between speaker's drivers at crossover frequency.
(7) Triplett 9320 True RMS 1000 amp clamp on AC / DC digital ammeter and digital multimeter,
To measure AC wall outlet current to the receiver.
(8) 1200 watt speaker dummy load with 2 channel input with a maximum power per channel of:
300 watt @ 8 ohms
400 watt @ 6 ohms
600 watt @ 4 ohms
1200 watt @ 2 ohms
To test the receiver's maximum power rms audio output into the dummy load.
Amount Paid (US$): 94.75
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