4 8 or 16 ohms.
Hi group I just purchased the Audio Research REF 750s mono amps. On the back for the speaker terminals are 3 sets of binding posts. 4 8 and 16 ohms. I will be using B&W Matrix 800 speakers. I believe they are 8 ohms but not 💯 sure. I looked in the manual but can’t find anything about ohms. Someone said to me it does not matter what ohms I connect my speakers to. He said just use the ones (ohms) that sound best. Does that seem right to do ? I don’t want to damage my speakers or amps.  BTW if it matters I will be using an Audio Research REF 6SE pre amp.Â
@tattooedtrackman If you bought the amps used, it behooves you to have a AR tech go through the amps and verify tube performance on a proper test that tests valves as run, not just go/nogo. While tubes maybe matched when new, they age and may not match with as few as 500 hours.
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@ieales   Yes I did buy them used. Previous owner put on 600 hrs on tubes and only had to bias them one time. I also bought a brand new set of matched (40) KT150s brand new from the seller that was bought from Audio Research. |
Biasing often adjusts the current at a single point. I’ve never seen an AR REF750 schematic, so can’t comment on the efficacy of the bias adjustment as tubes on each OPT leg age. AR had very clever engineers so it’s likely very good. The REF 750 Service Manual is available on HiFi Engine, so it’s worth getting if you don’t have it. It details the biasing procedure. General Info for tube power amp owners: Tubes that don’t have the same Gm at various points, conduct differently and may increase distortion. Many tube amps have a single bias pot for multiple tubes and this may severely compromise performance. See Transconductance - Wikipedia & Matching by Gm or Ip? - The Amp Garage |
