K4003 Amplifier - How do I power it?

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#21
I pasted the cpemmas wiring picture on the velleman board and got this reply from one of the staff.

If the information you supply is correct, we assume that this will work.

Do not connect the earth to the gnd.
Click to expand...

heh, I have so many differing opinions im not sure what to do. The Velleman rep says that the previous wiring diagram will work so long as i remove the earth.
 
#23
I hate to bump this thread so much but I am really stuck with this project atm. I know what you mean about wiring the secondaries in series but its better to be 100% sure than 99% sure.

Could someone please edit the diagram to illustrate the new wiring?
 
#25
myspacer00 said:
I pasted the cpemmas wiring picture on the velleman board and got this reply from one of the staff. The Velleman rep says that the previous wiring diagram will work so long as i remove the earth.
Click to expand...

This gets complicated and I was trying to avoid complication.
  • The mains supply earth wire should be firmly connected to any exposed metalwork - simple safety.

  • In a quality amplifier (or one operating at supply voltages above 24V from ground) you'd probably set up a star earth point taking in speaker negatives, supply 0V, board 0V, etc, and connect this to the mains earth point through a 'ground lift' gizmo such as a the R1/C1/D1/D2 combo shown on Fig.1 here.
However, the same Rod Elliott regarding a more modest amplifier writes, "Signal earth (the triangle) and mains earth should be tied together at a common point, which will become the 'star' earthing point for the whole amplifier... The main earth must connect to the chassis to prevent electric shock in case of a transformer "meltdown"."

Try the '0V to earth' connection; if you experience hum then experiment. With your 16V rails I can't see Vellemann's recommendation to not earth the 0V line as dangerous and should your signal source provide a path to mains earth through its own wiring and the interconnect screening it will eliminate one likely source of hum.
 
#26
cpemma said:
With your 16V rails I can't see Vellemann's recommendation to not earth the 0V line as dangerous...
Click to expand...

Can't edit above post so a proviso;
From http://sound.westhost.com/earthing.htm
This (Vellemann-style) provides protection should there be a failure from the incoming mains to chassis, but provides none at all if the transformer were to develop a fault between primary and secondary windings. Such faults are uncommon, but they can (and do) occur.
Click to expand...
 
#27
Hi. Using the wiring original wiring diagram posted by cpemma I have been able to achieve power to the the amp unit.

My problem now is concerning the actual audio. I have 2 speakers now attached and a 3.5 jack line in.

When playing music through an MP3 player the audio has extremely bad interference and crackle. When simply touching any wire (speaker, power, line in) the crackle changes louder or softer.

Also the amp appears to only be playing one audio line as instruments can be heard well but vocals are barely audible.

I have checked for cold solders on the PCB and have not found any.

Any advice on what may be wrong?

Thanks
 
#29
Hi all
As there seem to be some discussion on earthing and specifically on the K4003 in this thread I'd like to ask some of my questions:
- Is earthing advisable for a plastic or wood enclosure as well as a metal one?
- If not is a figure 8 power cable sufficient or is a kettle lead preferable?

thanks in advance
Baz
 
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