On Thursday, 19 September 2019 11:00:48 UTC+1, Trevor Wilson wrote:
On 18/09/2019 7:53 pm, Howard Stone wrote:
Well the Radford is back and it has been working well for the past week=
, with my little Rogers JR149s. The bass is MUCH tighter.
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**Than what? The Krell or the unrepaired Radford? The Krell possesses an=
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almost perfect bass response and low output impedance, thus bass will be=
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as good as it gets. The Radford, although a decent enough amplifier=20
cannot hope to match the Krell numbers. That said, the high(ish) output=
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impedance, common to most valve amplifiers, can lead to a pronounced=20
bass 'hump' at the resonance peak/s of the speaker system. The bass peak=
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may be preferred by some listeners.
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My plan is to hold on to it for a couple of weeks or so, just to enjoy =
it and get to know it better. Then I'll send it for a thorough service.
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I think the big thing I've learned, thanks to my adventures with the Kr=
ell and the Radford, is that the amp really does matter a huge amount. I'd =
underestimated that before.
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**Of course it matters. On one hand you have a 'blameless'
amplifier (Krell) and, on the other hand, you have an amplifier that=20
insinuates it's own sonic character. The Krell exhibits a ruler flat=20
frequency response, excellent phase response, inaudible levels of THD=20
and is load invariant, down to below 2 Ohms. The Radford is the=20
opposite. It's frequency response varies with the applied load=20
impedance, it's phase response is not flat at frequency extremes and=20
distortion is high(ish).
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--=20
Trevor Wilson
www.rageaudio.com.au
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Re the Radford, I can't see the frequency response curve online. The guy wh=
o rebuilt my Krell said (before he's experienced the KSA50 -- so that may h=
ave changed his perceptions) "The Radford STA25 is probably the best power =
amp I've ever heard at any price.. in the top few anyway. Coincidentally (h=
a!) it happens to be the best in electronic engineering terms, design, and =
measured performance, with lower distortion, wider frequency response and h=
igher damping factor than any other valve power amp I've measured."=20