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Parallel SET with sufficient power

Hello all:  I'm looking to move back into SET land after 15 years. I have a pair of KEF Reference 3's at 88 dB sensitivity which I'd like to keep, so I'm considering a parallel Single Ended design with at least 30 WPC. I do like the '300B sound' so friends have recommended the 6C33c tube in parallel to deliver 30-40 WPC. I've read some very positive posts on Audio Mirror and Wall Audio of Germany was briefly mentioned. Smaller boutique like companies give me some concern as most of these fine designers or engineers build amplifiers in their spare time, and quality control may be compromised.  I'm not a huge fan of 211 or 845 sound but these amps are another option.  Thanks for allowing me to think out loud and I do appreciate all opinions!

normie57

Showing 2 responses by almarg

almarg's avatar
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almarg
9,670 posts
 
George, are you sure that TubeGuru amp actually has a 4 ohm tap?  I couldn't find a rear panel photo, but I would interpret this photo, which is one of those shown for that amp at the TubeGuru site, as suggesting that it may have only a single output tap.  Also, the website description states "Output Impedance: 4-16 OHM," which could very conceivably mean that there is only a single output tap, with those numbers being the limits of the range of speaker impedances that tap is recommended for use with.

Regards,
-- Al
    
almarg's avatar
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almarg
9,670 posts
 
I'd be cautious in extrapolating from experiences others may report with various SET or PSET amps, unless they were using the same or similar KEF speakers.  As shown in Graph 4 of  this review the impedance of your speakers varies from around 3 ohms in parts of the bass region to as much as 18 ohms in the upper mid-range/lower treble.  The interaction of that impedance variation with the relatively high output impedance of most SET and PSET designs will in many cases result in weak bass and an over-emphasized upper mid-range/lower treble.  To a degree that will vary considerably among different SET and PSET designs, due to their differing output impedances.

An audition with whatever amplifier you may end up considering, using your speakers, would therefore seem particularly in order. 

Good luck.  Regards,
-- Al
 
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