In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
There is IIRC a 2.2 Ohm ressy in the quad to prevent that problem if a three pin mains lead of the IEC type is used, and used they are in "upgraded" QUAD 303's
Or a non standard quad mains via the bulgin
In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
Right!, so the crossover then goes to some home-brew amps if so what are they and are they bal or unbal inputs?..
Can I ask where that 2.2 ohm resistor went?
Both the 33 and 303 came with 3 pin Bulgin. If you used the 303 stand alone, you used a three core mains lead. If used with the 33, the 3 core for the 33 only, and a supplied two core from the switched mains outlet on the 33 to the 303.
Not quite sure what they did on the 405-2 series amps. That has an IEC input and IEC output. Both earthed. But never had a 4 Series pre-amp or tuner.
Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop problems...
They have some serious CMRR.
I doubt the X/O has anything like that?
I didn't recognise the number on the balance ICs in the X/O.
I have loads of SSM 2143 I could try, though, on the amp. But I've not had problems with either before.
Because the cable run is so short, I've just used the most basic circuit for the THAT1240.
But
In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
Apologies remembering wrong! Nothing out of the ordinary in that circuit..
Yes could have written that a bit/lot clearer the bulgin 3 Pin does have an earth on it using a two core mains cable partnered with the 33 as they probably couldn't get a Three pin outlet which does make the audio screened lead earth the protective earth.
Not good engineering really on Quad's behalf:(..
In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
They fed by a + volt and a neg volt supply centre tapped or floating do you know?..
What the THAT chips, if so how so?..
In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
Wouldn't surprised if they were pin compatible!..
It really shouldn't matter those sorts of chip can take balanced lines up to miles long if need be!..
I've got/getting rather then theres something odd with the power supply for these somewhere?..
Can you describe it in more detail?..
Of course I know. I built them. ;-) +/-15v.
They are. I was led to believe the THAT had a better performance than the SSM.
Quite. I've used them for lots of things with no problems. I have 5 stereo pairs of audio running round the house. Cable is multicore telephone cable
- no screens at all. Driven by SSM2142, and picked up in several locations by either SSM2143 or THAT1246. Can have 8 sitting across the same line with absolutely no problems at all.
Mains ground goes to the closest chassis point. All the DC grounds and signal grounds go to a star ground point which is in turn grounded to the chassis at only one point.
In article snipped-for-privacy@davenoise.co.uk>, Dave Plowman (News) snipped-for-privacy@davenoise.co.uk> scribeth thus
So transformer - separate windings- bridge rectifier- single three pin Voltage REG pos and neg points connected to appropriate pins and other ends come to a central earth or rather 0 Volt point?..???
Not quite.
The amp PCBs include the balance IC. The +/- 15 v derived from the amp
+/-50v. Same as Quad used on the 405 PCB for their op-amp.
A similar problem of detecting which of a number of speakers was producing sound from a device which changed characteristics when you approached it was diagnosed by a length of hosepipe taped near the device on one end and held near the observers ear at the other so you could listen closely without interfering with the equipment. In that case the problem was with the infamous Sinclair X10 broadband jammer which altered its characteristics as someone across the street moved around their lounge.
Yup. Bit the same as balancing twin SU carbs. ;-)
But in this case anything seemed to stop the buzz as you got it near. Which was what was so odd - I've never come across anything like it on audio gear. That was with the XLR screens floating at one end. Connecting them made the buzz permanent. And it was coming from all three speaker units. Removed the mains ground from the X/O, silent as the grave. ;-)
Hopefully up the back passage of the courier.
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