Mono Blocks for B&W 801 s3

Hello Mh_stevens

A couple of thoughts based on your information.

my cables are very expensive 20' TARALABS but no great gauge.

Direct from the 801S3 owners manual.
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The matrix 801 series 3 is provided with two sets of input terminals. This enables the low frequency unit and the midrange and HF unit to be wired with separate cables, thus removing the possibility of intermodulation of low and high frequencies in the cables.
Since the currents involved when playing playing loud music can be large, and the high cable resistance can alter the response of the loudspeaker, it is recommended that the cable cross sectional area not be less than 1.5 mm for runs of up to 3 metres and correspondingly larger for longer runs.
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The key part based on your situation.

"it is recommended that the cable cross sectional area not be less than 1.5 mm for runs of up to 3 metres and correspondingly larger for longer runs"

You are running 20 feet - about 6 meters. That is a very long run. Curious to the gauge of the wire.

Sound is good but there is a depth or strength missing, particularly when volume is moderate.

By chance are you using the B&W BAF as designed for the 801 S3 ?

There is a low frequency db drop off without the BAF especially in a compromised room that does not allow the speaker to breathe.

I received this graph direct from England years ago showing 801 matrix frequency response.
with and without the BAF

Also fwiw as you are a current Krell user;

When heading up Krell, Dan D'Agostino felt so strong with John Bowers about the active BAF requirement for the 800 matrix series, that he had Krell make their own version.

Krell B&W BAF

My room is a problem; it is very wide but only 13' deep with an alcove facing left speaker and an open arch facing right

Have you tried setting them up to shoot down the long wall, or is this not an option.

I once borrowed a 600 wpc McIntosh tube amp and it was superb.

Power corrupts.
I have not yet come across any speaker which when fed more power from an appropriate amp did not improve.
This is not to say that running a 50 - 600 wpc speaker on 250 wpc does not sound good and to be adequate for the room.
But once you hear what having so much amp headroom, and having the amplifier just cruise on music peaks sounds like. It is addictive.
Again this is based on the room volume, speaker placement, listening position and habits.

Anyway just some thoughts as I have my morning coffee.

Cheers.

" I once borrowed a 600 wpc McIntosh tube amp and it was superb".

Are you sure that wasn't a Solid State amp? McIntosh makes some great sounding ones. I have not heard of a 600 watt per channel McIntosh tube design.

Might be late to the party here but OP how handy would you say you are? I ask this because if you are handy then might I suggest building a few Hypex NCore Amps for your setup.

For the price range your shopping in you could build x 4 NCore MonoBlocs to make those B&W's sing like a champ.

I myself have x 4 of these recommend amps powering my B&W 803diamonds and they sound impressive with this much power. I've got x 1 MonoBloc powering each half of each speaker channel and they sound effortless at all volume levels.

One big added bonus to such a configuration is that you can run very short speaker cables (mine are only 2ft) to each cabinet since the amps sit nicely behind each cabinet.

I don't think you will be disappointed doing the same

Replacing a Krell KSA-250 with an Emotiva XPA-1L is similar to driving a vintage 80's Corvette to pedaling a rusty Huffy bicycle! C'Mon Man!!!

I concur, Dayglow. Emotiva does have good power ratings, but the sound is absolutely not high end. More like upper mid-fi at the most.