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SergeAuckland last won the day on May 13 2018

SergeAuckland had the most liked content!


1,592 Excellent


About SergeAuckland

  • Rank
    Certified Measurist
    Veteran Wammer

Personal Info

  • Location
    Bury St Edmunds, UK
  • Real Name

Wigwam Info

  • Turn Table
    EMT948, TRS9000, BD1
  • Tone Arm & Cartridge
  • SUT / Phono Stage
    In turntables
  • Digital Source 1
  • Digital Source 2
    Meridian 206
  • DAC
    DEQ & DCX
  • Pre-Amp
    Meridian 501
  • Power Amp/s
    3 x Behringer A500
  • My Speakers
    Active B&W 801F
  • Headphones
    AKG K270 KOSS Pro4AA
  • Trade Status
    I am not in the Hi-Fi trade

Recent Profile Visitors

6,551 profile views
  1. Hi serge could you please take a look at my post on active tweeter as would really appreciate some advice, not able to mail you directly for some reason. Thanks

  2. But only if one's daft enough to let an amplifier clip. Under clipping, SS amps have vanishingly low levels of distortion. It's also not true that valve amplifiers have mostly 2nd harmonic distortion, just look at the distortion spectrum of any PP amplifier, 2nd harmonic is suppressed, and as distortion rises, so does a spray of upper harmonics. Valve amplifiers can sound louder, but that's just because we associate higher levels of distortion with loudness. Use an SPL meter, and it's not louder, just sounds that way. S.
  3. Indeed, watts is watts. Valve watts are no different to SS watts. However, SS amps have vanishingly low distortion until they clip, at which point distortion rises rapidly, whilst valve amps have distortion that rises from relatively low levels to quite high levels, and in the case of low or no feedback valve amplifiers, don't have a clear clipping point, just increasing levels of distortion. As increasing distortion is perceived in part as increased loudness, it's not surprising that it's often thought that valve watts are somehow bigger than SS watts, but a meter soon disabuses one of that perception. Watts IS watts, but SS watts are generally a lot cleaner than valve watts, especially at high levels. That's why amplifiers have their output power specified for an amount of distortion. S
  4. I think that faster was better was known about since the days of germanium transistors with a Ft of only 450kHz! (AD149) One of the limitations of valve amplifiers was the limited open-loop bandwidth and accompanying phase shift that limited the amount of feedback that could be applied before the amplifier turned into an oscillator. Early transistor amps did a bit better, but not a lot. Once Silicon transistors became available with a minimum Ft of 2.5MHz, (2N3055) things got better and modern devices do a lot better than that. The downside is that with higher frequencies came more stability problems, but those were well understood fairly early on. "The wider you open the window, the more muck blows in." Variously attributed to Cecil E. Watts. Modern amplifiers have open-loop bandwidths that are sufficiently high that almost any amount of feedback can be used without stability problems in the audio range. Care still needs to be taken with RF instability, but again, that's well understood. S.
  5. That's pretty much my view of component 'quality'. I've never come across 'better' components improving audio quality, if the original components were adequate for the task they were being asked to perform. Properly rated normal commercial-grade components are fine, 'audio' grade just seems to me a way of extracting more money unnecessarily from the gullible. If changing a component makes a measurable improvement, the original component was inadequate, and wrongly specified. S.
  6. That's my sort of construction!! Did you evaluate what sort of shoe box sounded better? S.
  7. I don't know why, probably just familiarity, but the Ortofon looks so right on the 505. S.
  8. Just the opposite. There seem to be plenty of audiophiles willing to accept what they feel from sighted tests rather than carrying out properly conducted blind testing. Why do amplifiers only sound different when auditioned sighted? You really need to read Floyd Toole's book. S
  9. Yes, but that article addresses a marketing issue, not a technical one. Class D amplifiers have had decent technical specs for many years. That some 'audiophiles' still think they sound different is their problem, not one that stands up to technical evaluation(and blind testing). S
  10. Who by and how long ago? Class D amps were available in the late 1960s, and yes, they weren't very good due to limited output device switching speeds, but those made in the last, say, 20 years have been fine. S
  11. As much as I respect Peter Walker, and he is definitely up there as one of my top two or three audio engineers, it shouldn't be forgotten that Current Dumping was a joint development together with Mike Albinson, who I think had the original idea of Current Dumping. There's an interview with Mike Albinson here. http://www.quadesl.org/index.php/home/interviews/mike-albinson S
  12. Current Dumping is pretty much in its own class. It consists of a small (3W in the case of the 405) Class A amplifier which can swing the full output volts, but provides little current. This small amplifier can be made to a very high performance standard in terms of low distortion and bandwidth. This small amplifier is supported by a pair of very rugged transistors, whose only job is to provide the current the small amplifier can't do. That's why they're called Current Dumpers. The amplifier doesn't use conventional negative feedback, it uses feedforward which maintains the error between input and output to a very low level. When the 405 first came out, there was lots of correspondence in the technical press as to what Current Dumping really meant, as it was a completely new technique, not even something that had ever been done before in other fields than audio. S.
  13. No, because a transient of one cycle of 20KHz needs a bandwidth of 20kHz. All audio signals are band limited, CD to 20kHz with a very sharp cut-off, LP somewhat less, but due to the RIAA boost on cutting, the level has to be carefully controlled, so hard to say what the corresponding equivalent to a CD's cutoff is. If the transient is shorter than the equivalent of a 20kHz cycle, then it follows it's frequency is higher. In a system band-limited to 20kHz, no transient can be shorter. In the case of higher sample rates, then it's possible for faster signals to be present, but except for test tones, music has very little energy much above 10kHz, so even if the transient is there on a wider bandwidth system, the bandwidth needs to be higher, but the slew rate doesn't, as the amplitude is low. S
  14. That's a bit unkind, they're not that bad! S.
  15. Wow! What a selection! I wonder where that lot came from. S
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