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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#81
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Electronics funny.
In article ,
tony sayer wrote: In article , Dave Plowman (News) scribeth thus In article , Fredxx wrote: On 21/04/2019 00:15, Dave Plowman (News) wrote: In article , tony sayer wrote: I can't be certain the Behringer unit is faulty. The amplifiers are home made, and it could be some interaction I've not fathomed out. Right!, so the crossover then goes to some home-brew amps if so what are they and are they bal or unbal inputs?.. 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. Wouldn't surprised if they were pin compatible!.. They are. I was led to believe the THAT had a better performance than the SSM. Because the cable run is so short, I've just used the most basic circuit for the THAT1240. But It really shouldn't matter those sorts of chip can take balanced lines up to miles long if need be!.. 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. I've got/getting rather then theres something odd with the power supply for these somewhere?.. Can you describe it in more detail?.. 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. -- *Just give me chocolate and nobody gets hurt Dave Plowman London SW To e-mail, change noise into sound. |
#82
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Electronics funny.
In article , Dave Plowman (News)
scribeth thus In article , tony sayer wrote: In article , Dave Plowman (News) scribeth thus In article , tony sayer wrote: I can't be certain the Behringer unit is faulty. The amplifiers are home made, and it could be some interaction I've not fathomed out. Right!, so the crossover then goes to some home-brew amps if so what are they and are they bal or unbal inputs?.. Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop problems... They fed by a + volt and a neg volt supply centre tapped or floating do you know?.. Of course I know. I built them. ;-) +/-15v. 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?..??? http://www.thatcorp.com/1240-series_...iver_ICs.shtml -- Tony Sayer Man is least himself when he talks in his own person. Give him a keyboard, and he will reveal himself. |
#83
Posted to uk.d-i-y
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Electronics funny.
In article ,
tony sayer wrote: They fed by a + volt and a neg volt supply centre tapped or floating do you know?.. Of course I know. I built them. ;-) +/-15v. 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. -- *Don't squat with your spurs on * Dave Plowman London SW To e-mail, change noise into sound. |
#84
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Electronics funny.
On Sat, 13 Apr 2019 13:00:37 +0100, "Dave Plowman (News)"
wrote: Difficult to tell if the buzz is from all three speaker units, as when you get your ear close enough to each one, it stops. 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. |
#85
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Electronics funny.
In article ,
Peter Parry wrote: On Sat, 13 Apr 2019 13:00:37 +0100, "Dave Plowman (News)" wrote: Difficult to tell if the buzz is from all three speaker units, as when you get your ear close enough to each one, it stops. 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. 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. ;-) 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. -- *Does fuzzy logic tickle? * Dave Plowman London SW To e-mail, change noise into sound. |
#86
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Electronics funny.
On Sat, 20 Apr 2019 15:18:48 +0100, "Dave Plowman (News)"
wrote: In article , tony sayer wrote: Quad at that time only grounded the pre-amp. Everything else had two core mains leads. Using 110v mains plugs. ;-) 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 Can I ask where that 2.2 ohm resistor went? Hopefully up the back passage of the courier. |
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