One comment

  1. “..three band Tube EQ engineered with an ingenious filtering system that allows the even harmonics to flow thru the 12AT7 tubes filtering out unwanted noise”

    Yeah right! You know what I think of bumpf like this Paul! Really, they should try different marketing speak because it just puts me off. Some of the things look okay. Remember, you can see the guts inside and cost stuff out yourself. Usually, it’s the knobs and the case that cost the most (except if they insist on using transformers). So you can make your own stuff or buy it…it just depends if you ever intend to sell the equipment on. If it’s for your own use and you have a bit of time, then make your own. The chips they tend to use aren’t monolithic. They seem to be what used to be called potted, where the capsule contains an op-amp, say, a couple of low noise transistors and a few extra resistors etc. I’ve forgotten the name for this contruction right now.
    However, Mr Self has pointed out a new op-amp, the LM4562 with pretty good characteristics at http://douglas-self.com/ampins/webbop/LM4562.htm

    The manufacturers site and UK shops have it going for £3 which is pretty good for two HQ low noise, high slew rate op-amps. That’s all you need to make your mixer, apart from the resistors etc.

    Check out Mr Self’s words at the bottom of his Soundcraft mixer page http://douglas-self.com/ampins/mixer/mixerdes.htm

    It’s a really neat summary and I quote:
    “PERFORMANCE FACTORS.
    Primary requirements of modern consoles are very low noise and minimal distortion. Since a comprehensive console must pass the audio through a large number of circuit stages (perhaps over 100 from microphone to final mixdown) great attention to detail is essential at each stage to prevent a build-up of noise and distortion; often the most important trade-off is the impedance of the circuitry surrounding the op-amp, for if this too high Johnson noise will be increased, while if it is too low an op-amp will show degraded linearity in struggling to drive it.

    The choice of device is also critical, for cost considerations discourage the global use of expensive chips. In a comprehensive console like the 3200 with many stages of signal processing, this becomes a major concern; nonetheless, after suitable optimisation, the right-through THD remains below 0.004% at 20dB above the normal operating level. At normal level it is unmeasurable.”

    That “unmeasurable” word is the one I like!

Comments are closed.