Hi everyone, My current setup consists of: Project Debut III, Rotel RA-920AX and a pair of Wharfedale Diamond 9.1's - I'm looking to upgrade the speakers and amplifier. I like the sound of the Rotel kit, so I'm looking to upgrade it, but stay more or less with the more classic kit. I know the mismatched impedence question has been asked hundreds of times, but what I'm struggling with is whether I can use two Rotel RB-970AX power amps with the Wharfedales (the Wharfedales are only a stop-gap while I save up for something more exciting, probably B&W CM1, Focual Chorus or B&W 685 S2) but I'd like to get the amps in place so when I get the new speakers I'm ready to go. The Rotel RB-970AX is rated for a minimum of 4 ohms in stereo mode, but in bridged mode they're rated for 8 ohms. Is this going to be a real problem? The Wharfedales have a nominal impedence of 6 ohms and are rated for up to 100 watts.
Rotel Mono-blocks for 6 ohm speakers
- Thread starter gilphilbert
- Start date
Sorry, yes. I left that off - I'm planning on getting the matching Rotel RC-970AX to go with the power amps.
The general rule when using bridged amplifiers is that you get 'twice the power into twice the impedance', so ig the amps are rated down to 4 ohms in stereo, that will be 8 ohms when bridged.
Realistcally these figures have are not totally exact, there is a bit of 'wriggle room' so your 870s should be fine providing you use a little common sense, ie don't drive them flat out and keep an eye on how warm they run.
For what it is worth I used to use 870s and mostly 860s in modest background music type systems in bars, shops and the like. We would usually run 2 pairs of speakers off each amp, ie a 4 ohm load, with no issues whatsoever.
Not quite your situation, but testimony to the ruggedness and reliability of these models when worked quite hard.
Realistcally these figures have are not totally exact, there is a bit of 'wriggle room' so your 870s should be fine providing you use a little common sense, ie don't drive them flat out and keep an eye on how warm they run.
For what it is worth I used to use 870s and mostly 860s in modest background music type systems in bars, shops and the like. We would usually run 2 pairs of speakers off each amp, ie a 4 ohm load, with no issues whatsoever.
Not quite your situation, but testimony to the ruggedness and reliability of these models when worked quite hard.
Sorry for the belated thank you for your advice everyone.
In the end I actually settled for to Rotel RB-971 power amps with a Rotel RC-970BX pre-amp connected to a pair of Tannoy Mercury V1 speakers as my "temporary solution" which are 8 Ohm speakers anyway.
I'm so impressed with this setup that I might keep it like this for a lot longer than I planned! Now I just need to add a good DAC and phono pre-amp, a pair of speaker stands and...
In the end I actually settled for to Rotel RB-971 power amps with a Rotel RC-970BX pre-amp connected to a pair of Tannoy Mercury V1 speakers as my "temporary solution" which are 8 Ohm speakers anyway.
I'm so impressed with this setup that I might keep it like this for a lot longer than I planned! Now I just need to add a good DAC and phono pre-amp, a pair of speaker stands and...
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