Phil Leigh;573807 Wrote: > Stop. I have an idea. Based on CliveB's observation that the pins on > your adaptors are actually wired up as per the website - and not as you > posted... > > I think what is happening is this: > > 1) the EC will not fire up unless it senses a medium level impedance > across its inputs - this must be based on some voltage or current > sensing circuit. This is done for good reasons - it's to prevent > destroying your speakers if you start the amp without anything > connected to its inputs and then plug something in - which can send > full-power transients through your speakers. > > 2) The Creek passive pre-amp puts an impedance of 5k ohms with the > volume control in circuit and about 10 ohms (!) from the fixed output. > This is obviously enough to satisfy the protection circuit. > > 3) The SB on its own is too high an impedance to activate the un-mute > circuit. I don't know what the output impedance of the SB is, but it's > going to be higher than a pre-amp - maybe 10 times higher. The EC is > expecting to be driven from a low-ish impedance source... > > That's the only explanation I can come up with that seems to fit the > facts to hand. > > As for a fix... well you really should have some form of passive > attenuation between ANY SB and a power amp anyway - for safety reasons. > I'd stick the Creek back in if I were you.
I'm no master in electronics... And I know the impedance could make a problem with sound, but I cannot imagine how the EC can complain or measure anything, if there's no signal coming. This means it's just 0V between signal and ground on both inputs, thus no current. As for the numbers, it seems the SB3 output impedance is 220 Ohms, which I found here: http://www.audiocircle.com/index.php?topic=23435.0 by comparison, my CD player (NAD C541i) has 200 Ohms, EC pre (which I don't own) has 100 Ohms. But as it comes to CD, I just found I actually didn't connect it directly, I always used a pre. The CD doesn't have any volume control. So I don't know, if this 200 Ohms are OK. Can the passive preamp (no power connected) make the impedance lower? as I imagine, it cannot, can keep the same when the volume is set to maximum, or make it even worse in other cases. But I'm no master in electronics as I wrote... I just checked the output impedance of the active pre which works fine. This is Rotel RA-02, which is a budget integra actually, but can be used as pre-amp as well. The output voltage/impedance of the pre outs is: 1V/470 Ohms. So actually over two times worse than SB3 - and still works with EC. It seems I will have time to test shorting plugs soonest tomorrow. If it doesn't work, it's maybe a good idea to contact Electrocompaniet, maybe they know the answer, or at least what the amp is checking for. As for safety, I know about the problem. -- azaz44 ------------------------------------------------------------------------ azaz44's Profile: http://forums.slimdevices.com/member.php?userid=21080 View this thread: http://forums.slimdevices.com/showthread.php?t=81664 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
