Newbie amp wiring help

I need some help wiring up my first amp, see attached drawing.
I've built a diyUniversalPSU and 2 diyHoneyBadger boards and have drawn how i think things should be wired from what i've learned so far but cannot find a solid answer on how to wire the PSUs to the amp boards and where the input ground should be connected.
Can someone draw some lines for me and correct me on my wiring if it's wrong?
 

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SINGLE wires do not work.
Every circuit to circuit connection must have a Flow and Return.
This module to module connection must use at least TWO wires to form that circuit.

The transformer has two secondary windings with 4 wires.
Keep the two windings separate and run a twisted pair from each winding to the PSU.

The output from the PSU is: +ve & zero volts & -ve
Run this as a twisted triplet to the amplifier.

The output from the amplifier is a two wire connection to the speaker.
Run this as a twisted pair to the speaker terminals.

The input to the amplifier is two channels, each channel having a TWO wire connection.
Run the input from the RCA as a twisted pair, or a coaxial, to the amplifier and repeat for the other channel.
 
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AndrewT, thanks for the response!

Sorry about the RCA jacks, I forgot I was working with stereo inputs. And sorry for the general ignorance.
I understand you want me to twist the flow and return wires on everything for noise suppression?

Also, i am unsure of where to connect the 0v line from the PSU to the amp boards and where to connect both lines on the RCA inputs. I'm guessing the PSU 0v goes to the SPKGRND on the amp board? Both wires from the RCA jack go to the 0v INPUT on the amp board?

Attached a modified drawing, can you please verify for me? Or draw wires for me, drawings can speak volumes more than words sometimes.

Thanks for the help.
 

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rayma

Member
2011-04-29 8:37 pm
the two PSU boards have a jumper at ST_IN2/3 and ST_G1/2 linking the two ground rails together.

Yes, that should be ok. Try to twist wire pairs. The RCAs should also be isolated from the chassis.
There should be some method to connect the PS ground to the chassis through some component,
like a rectifier block, parallel RC, etc.
 
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Cortez

Member
2002-12-26 9:45 am
Hungary
Can I have some basic questions about PS and GND wiring..?

It's popular nowadays to separate the IPS (LTP + VAS) + the OPS.
I am also planning to use my next amp this way see attachment.
Of course it wont be so far away it's just for understanding.
Let's see only 1 channel as a start anyways it will be a dual mono setup...

What is fix: IPS is taking the input that drives the OPS which gets PS rails and produces the output.
That's ok, my questions:

1) On the signal GND there is the input GND and the feedback reference GND.
This FB GND should be connected to the OUT GND point or rather from the OPS output GND point?
The same Q about the FB: where it's the best to take it from? From the "OUT" or from the OPS output point?

2) The OUT GND should be taken from the OPS (sharing with the local decoupling caps GND) or from the PS GND with a separate wire?

3) If the IPS gets a separate PS with dedicated PS wires is it okay to use it as it's on the image?
(The IPS PS "dirty" GND is completely separated from the "clean" signal GND,
on that "dirty" GND there are only the local caps, CCS etc...)
Or this creates some kind of loop because of the IPS vs OPS PS + signal (PD/ND drive + FB) wires?
Therefore the IPS PS wires should be going as close as possible to the OPS PS wires with zip tie?

4) And finally some theoratical Q abount GND loops and interference:
Why GND loops are mainly a problem? Just because there is never a loop for the rails by accident?
And what is the source of this interference? Only a trafo or it's "in the air" anyways because of the mains?
For example if I'll use SMPS GND loop will still be humming? (Of course that's not my goal, I am just curious...)
And why a loop break 10R sometime solves the hum, just because there is no current in the loop,
why the generated voltage does not cause any trouble?

Please tell me if the image is not clear enough.

Thanks!
 

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Replace all the inter-module connections with the correct two wire connections.
Then look to see if you have made EVERY signal connection with a close coupled wire pair.
After that look to see if you have omitted any voltage reference links shown in the original schematic/s
Finally check to see if there are any loops around which interference current can circulate.
 

Cortez

Member
2002-12-26 9:45 am
Hungary
Here is the "all-wire" figure, but the questions are still open:
Reference numbers are same on the figure.
Orange: signal (and feedback) GND
Purple: all dirty PS GND + output GND
PD/ND: IPS driving the OPS +/- wires

#1: Where should I take the SGND and the FB point from?
From the "OUT" (loudspeaker terminals) as shown or from OPS PCB and why?

#2: Where should I go with the OUT GND?
To the OPS PCB or directly to the PS GND as shown and why?

#3: Can I form a "loop" with the IPS PS wires regarding the OPS PS wires?
Is this a real loop at all or not?
 

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Cortez

Member
2002-12-26 9:45 am
Hungary
No one?
Regarding Q #3: I am asking because it's not clear which one is worse/better:
- leading the the IPS/OPS PS wires far from each other and so decrease the possibility to inductive coupling between them, but creating a "loop"
- or to lead them by one common "axis" eliminating the loop, formed by the paralell PS wires, but maybe increasing the inductive coupling between them..?
 
OK,
now I see what you are proposing.
I was expecting you to analyse your proposal, but you seem to be looking for comments.

Signal IN.
use a twisted pair or coaxial from two connections at the input socket to two pads on the IPS

PS
use a twisted triplet from PS to OPS
use a twisted triplet from PS to IPS

IPS
IPS sitting isolated away from all else leaves me confused.
Two sets of close coupled wires come from IN and from PS
use a twisted pair for PD/ND But is there another current that complements this connection?
I cannot see from this diagram.

OPS
use a twisted pair for the output to the speaker OUT
The wire #2 looks to be an extra that creates a loop.
The feedback taps into the OPS output and feeds back to the IPS. Inside the IPS the feedback splits to signal return and to -IN node. But you must identify the route this current takes from Source to load and back to Source. This route must be formed into a close coupled pairs, otherwise any widely separated LOPS become aerials picking up interference.

Compare all these pairs to the original SCH and find what voltage references and other links are missing. One to look for is the Signal Return to Speaker Return voltage reference link.
 
Thanks a lot Andrew!

Yeah, I would like to have some comments on the possible arrangements, because
I cant simulate these loop induced interferences, or is there a method maybe..?

> IPS sitting isolated away from all else leaves me confused.
Why? I plan to put my OPS PCB on the heatsink but I dont have any space
there for the IPS which will be on the bottom mother board of the case.
In such an arrangement I'll have 2 separate module which I can wire in many ways.

> use a twisted pair for PD/ND But is there another current that complements this connection?
> I cannot see from this diagram.
What are you thinking of under "complementing"?
Between the IPS and OPS only these wire are going:
- driving: 2 wires: PD/ND
- feedback: 2 wires: OUT (hot), OUT GND (cold)
(Which are the same as the loudspeaker output points but located on the OPS PCB...)

> The wire #2 looks to be an extra that creates a loop.
If the loudspeaker GND goes diretcly to PS GND (instead of OPS PCB PS GND) then there isn't.

> The feedback taps into the OPS output and feeds back to the IPS.
> Inside the IPS the feedback splits to signal return and to -IN node.
> But you must identify the route this current takes from Source to load and back to Source.
Yeah but that's exatcly which is not clear to me: where is this feedback loop?
Everything starts at the PS: so I guess the path is something like this:
  • START: PS "+"
  • OPS PS "+"
  • OPS OUT
  • feedback point
  • IPS feedback entry point
  • signal splits:
    • FB resistor: to IPS signal GND
      • OPS GND
      • and finally: PS GND
    • "inverting input": to IPS "-" PS, right..?
      • IPS PS "-"
      • and finally: PS "-"
Am I right?
 
You need to analyse your proposal.
You need to mark out the current routes that each signal will follow.
Where current circulates around a route (from source to load and back to source), you need to make sure you have minimised LOOP AREA. That applies for inter-module connections and ALSO applies on a PCB.
If the loudspeaker GND goes diretcly to PS GND (instead of OPS PCB PS GND) then there isn't.
you don't have the option to separate the two speaker signal wires and run them to different destinations !!!!!!!!!!
OPS
use a twisted pair for the output to the speaker OUT
 
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Cortez

Member
2002-12-26 9:45 am
Hungary
I can't analyse it because I have a question that blocks it thats why I asked...

Speaker GND: yes I have the option, I used this layout already without any problem.

Even the separate IPS/OPS PS wires were working, I am just asking to discuss this
topic and maybe get an even better understanding/solution.