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About psmith

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  1. psmith

    CAT7 as tonearm cable?

    Perhaps I should have made it clear that I envisaged removing insulation, shielding, and spare conductors from the section inside the arm. Is it still too inflexible after you have stripped off the outer insulation and shielding and the inner insulation and shielding, and truncated four of the signal wires for the section which runs inside the arm? I know the signal wires themselves are quite stiff, but they only have to allow 40 degrees of rotation at the pivot. As regards weight, the additional moment of the four signal wires along the arm is going to be minimal, and produce a tiny, perhaps even beneficial adjustment in frequency response. If that little mass made such a difference, then every cartridge design would have to have a proscribed arm for each season/latitude.
  2. Has anybody tried CAT7 as a tonearm cable? It ought to be quite good, ought it not? Low capacitance, lightweight signal wires, shielding. What do you think?
  3. Thanks Serge, that's reassuring. How does one go about measuring the impedance presented to an amp by a driver? Is it only the frequency range that will be sent to the driver which matters, or should measurement extend beyond that? Presumably the DC resistance is important in considering what would happen in the case of amp malfunction... Also, is there any way of finding out whether the switch-on thump of my A500 is actually dangerous towards the 242's high frequency drivers? Maybe they can handle it. Do I need to ask Linn what kind of signal is destructive to the 3K array drivers?
  4. Thanks Serge. On another thread someone has warned that prophylactic capacitors will introduce a phase shift. My A500 is quiet when switched off, but produces a bit of a thump when switched on. I'm not sure the super tweeter on my Linn 242 could handle the regular abuse. I'm leaning towards using a more expensive stack of amps. Still, how hard would it be to replace the gain knobs with reactive circuits which unmute shortly after powering up? Surely a sensible arrangement of capacitors and resistors can do this.
  5. Thanks for your ideas. The amp is currently driving a pair of EPOS ES14, and I'm pretty happy with it. Elsewhere I've just been told that the individual drivers of the 242 are 4 ohm and above, so I'm less worried about the load now. It's just the switch-on thump issue that needs a solution. I have been looking at the Crown XLS amps too, and they look like they might be a better option all round, although they are twice the price of the Behringers. Hard to confirm whether they have switch-on thump though.
  6. I have a Behringer A500 which produces a switch-on thump, as I understand is normal. I want to drive active tweeters with it, but am worried that the thump will fry them since there is no crossover. As I understand it there is no thump when gain is set to zero on the amp's face. Turning the dials each time I power up and down is not an option, and would leave the tweeters exposed to power cut risk. Would it be possible to replace the gain knobs in the circuit with a circuit which effects zero gain at power-on, but rises to max gain after a second or two, and resets to zero gain shortly after the amp loses power? I am ignorant about electronics but it seems to me that such a circuit ought to be quite simple to design for someone who understands these things. This should solve my problem by obviating any switch-on thump reaching the tweeters except in the case of very rapid power-cycling. Please point me in the right direction.
  7. Anybody? Am I asking the wrong questions?
  8. I'm trying to work out if I can drive my active Linn 242 mk II with Behringer A500. There seem to me to be two obstacles: 1) the A500 isn't safe with a load less than 4 ohm, and it looks like even the passive 242 presents less than 4 ohm at some frequencies. 2) the A500 produces a significant switch-on thump and buzz, which may represent a threat to actively configured tweeter and super-tweeter. I'm not prepared to zero the gain knobs on the A500s at switch-on as a way of avoiding thump, because sometimes we have power cuts, and blowing the tweeters will be expensive. Is it possible to solder a protective capacitor into the tweeter/super-tweeter amps to block the thump while retaining nearly full pass for the wanted frequencies? My crossovers have limited gain adjusters for each channel. What can I do about the lowish impedance? Should I just use a better amplifier? My A500 sounds good at full gain and cost £130, so a five-pack of them would be satisfyingly affordable. If the best solution is an alternative amp model, can anybody suggest a similarly adequate, cheap and powerful amp which can cope with a 2 ohm load and never thumps?
  9. psmith

    EPOS ES14 Capacitors

    I'm sorry - I don't really see how that diagram relates to your description of wiring up the speaker. Anyway, let's leave it as my speakers only have one set of terminals, so I've no choice but to go inside them again if I want to add resistance to the tweeter.
  10. psmith

    EPOS ES14 Capacitors

    My speakers are early, as mentioned above, and only have the one pair of terminals connected to both drivers in parallel.I'm sure it's a clever idea but I haven't fully understood the circuit. As you describe it, how would the mid be powered?
  11. psmith

    EPOS ES14 Capacitors

    That would certainly explain what I'm hearing. As for making two changes at once, I just want to get to the point where I'm happy asap and then forget it. I don't really enjoy dismantling speakers and doing tricky soldering with two underpowered irons. DIY is the means to an end for me. Consequently, my next expedition into the speaker will be to remove the Vishays and add a resistor. Thanks for all your help and advice.
  12. psmith

    EPOS ES14 Capacitors

    OK, very interesting to hear. The link above in this thread delivers a page which states the following: I guess I'll just live with them in place for a few weeks, and then if I can summon up the energy to work on the speakers again, I'll remove the Vishays and see how I feel.
  13. psmith

    EPOS ES14 Capacitors

    Also, is "bypass" the right terminology? I'm totally ignorant of electronics, so please educate me. From a naive point of view, it seems to me that a 0.01uF capacitor is more or less the opposite of a "bypass", since it allows almost no current to flow, and barely affects the capacitance/reactance of the group.
  14. psmith

    EPOS ES14 Capacitors

    Thanks for all of the ideas, fellas. Obviously I'm getting conflicting advice on that. What will be the benefit of removing the 0.01uF Vishays? Either I'm getting used to the sound, or they are starting to sound a bit mellower, and quite good. As regards the internal cable, as I understand it, ES14 went through quite a lot of minor revisions as production continued. The internal wiring was labelled 'QED', but I don't think that's surprising when you consider the likely date of manufacture. These are early ones, with concave cups on the mid units, rather than torpedoes, and one pair of cable connectors on the back. The caps which I removed were small, metallic blue, and labelled '3mf'. They don't look to be in bad condition, but they certainly sounded quite different to the much larger Maplins 3.3uF caps with which I replaced them. I have to assume that the wiring and caps were original. I found no evidence of hint that the speakers had been modified, but perhaps someone more knowledgable might be able to shed light on that possibility, given my description of what I found inside. Serial numbers are neighbours in the early 700s. The internal wiring had lugs soldered onto the wires at the amp/connector ends.