I am a first time neophyte at this and know just enough to get me in trouble.
My intent is to set up four separate zones in my home containing two pair of 8 ohm speakers with each pair is to be controlled by impedance matched volume controls. I intend to use the amplifier's secondary (Zone 2) analog output for these zones. Unfortunately there is only one set of terminals for L & R speakers. The amp is designed to handle an impedance load between 6 and 8 ohms.
The problem I have encountered occurred when I initially powered up only two pair of speakers and had the amp's safety trip kick out after a while. The instruction sheet showed the speakers wired in a parallel circuit with the impedance matching switch set to one of three settings1/2 X , 4X , or 8X depending upon the number of speakers connected. To trace the problem I began checked resistance to determine if either the speakers or volume controls were defective. I realize that static DC resistance is actually lower than operating AC impedance but thought that it might point me in the right direction. This table shows my resistance readings of the individual speaker pairs and the pairs connected in parallel and in series.
No. of 8 ohm pairs...............1 to 2.........3 to 4.........5 to 8
Switch Setting....................1/2 X...........4 X.............8 X
Pair #1...................L..........3.6 Ω..........4.7 Ω..........7.5 Ω
............................R..........3.6 Ω..........4.8 Ω..........7.6 Ω
Pair #2...................L..........3.5 Ω..........4.7 Ω..........7.1 Ω
............................R..........3.7 Ω..........4.9 Ω..........7.1 Ω
Parallel...................L..........1.9 Ω..........3.0 Ω..........3.6 Ω
Connection.............R..........1.9 Ω..........3.0 Ω..........3.6 Ω
Series....................L..........7.0 Ω..........9.5 Ω..........13.6 Ω
Connection.............R..........7.0 Ω..........9.5 Ω..........13.6 Ω
I was surprise to find that the recommended parallel connection with the switch set to 1/2 X for these two pairs gave me a resistance load of only 1.9 ohms! Is it any wonder the breaker tripped? When switched to the 8X setting (for 5 to 8 pair) the reading went up to 3.6 ohms. Just the opposite of what I expected. I then took it one step further and set these two pair up in series to increase impedance and now the settings were in a more acceptable range when set to the 1/2 X setting.
I have contacted the manufacturer and asked if there could be a possibility that either the impedance matched volume controls had switch settings labeled incorrectly or whether the schematic showing a parallel circuit was drawn incorrectly. I am still awaiting a response.
I would appreciate receiving any thoughts or suggestions.
Many Thanks.
My intent is to set up four separate zones in my home containing two pair of 8 ohm speakers with each pair is to be controlled by impedance matched volume controls. I intend to use the amplifier's secondary (Zone 2) analog output for these zones. Unfortunately there is only one set of terminals for L & R speakers. The amp is designed to handle an impedance load between 6 and 8 ohms.
The problem I have encountered occurred when I initially powered up only two pair of speakers and had the amp's safety trip kick out after a while. The instruction sheet showed the speakers wired in a parallel circuit with the impedance matching switch set to one of three settings1/2 X , 4X , or 8X depending upon the number of speakers connected. To trace the problem I began checked resistance to determine if either the speakers or volume controls were defective. I realize that static DC resistance is actually lower than operating AC impedance but thought that it might point me in the right direction. This table shows my resistance readings of the individual speaker pairs and the pairs connected in parallel and in series.
No. of 8 ohm pairs...............1 to 2.........3 to 4.........5 to 8
Switch Setting....................1/2 X...........4 X.............8 X
Pair #1...................L..........3.6 Ω..........4.7 Ω..........7.5 Ω
............................R..........3.6 Ω..........4.8 Ω..........7.6 Ω
Pair #2...................L..........3.5 Ω..........4.7 Ω..........7.1 Ω
............................R..........3.7 Ω..........4.9 Ω..........7.1 Ω
Parallel...................L..........1.9 Ω..........3.0 Ω..........3.6 Ω
Connection.............R..........1.9 Ω..........3.0 Ω..........3.6 Ω
Series....................L..........7.0 Ω..........9.5 Ω..........13.6 Ω
Connection.............R..........7.0 Ω..........9.5 Ω..........13.6 Ω
I was surprise to find that the recommended parallel connection with the switch set to 1/2 X for these two pairs gave me a resistance load of only 1.9 ohms! Is it any wonder the breaker tripped? When switched to the 8X setting (for 5 to 8 pair) the reading went up to 3.6 ohms. Just the opposite of what I expected. I then took it one step further and set these two pair up in series to increase impedance and now the settings were in a more acceptable range when set to the 1/2 X setting.
I have contacted the manufacturer and asked if there could be a possibility that either the impedance matched volume controls had switch settings labeled incorrectly or whether the schematic showing a parallel circuit was drawn incorrectly. I am still awaiting a response.
I would appreciate receiving any thoughts or suggestions.
Many Thanks.
