Don't ground your signal.🙂 Polarity reversal in SE is done on the speakers inputs which are floating devices.
gotcha...I recieved my regulated PSU yesterday too so I will try and stuff that tonight as well and get everything sorted out tonight maybe.
well...no dice yet...
hooked it back up with signal to signal and rca ground to rca ground and nothing but terrible loud hummmm...switching speaker outputs made no difference.
I am thinking now that maybe my pot is not hooked up correctly...
What are your successful wiring schemes for your input to pot to board to output wiring schemes?
I have an alps blue dual pot.
I went RCA ground to pot ground. then ran another wire from pot ground to board ground input. Could this be causing my ground loop?
hooked it back up with signal to signal and rca ground to rca ground and nothing but terrible loud hummmm...switching speaker outputs made no difference.
I am thinking now that maybe my pot is not hooked up correctly...
What are your successful wiring schemes for your input to pot to board to output wiring schemes?
I have an alps blue dual pot.
I went RCA ground to pot ground. then ran another wire from pot ground to board ground input. Could this be causing my ground loop?
Pictures are worth a thousand words😉 Step away, play a game of chess or listento music, then recheck wiring. After pi cof course. If these guys got me up and running, i am sure they can help.
Just a suggestion - do you have three or four pin Alps pot?
The four pin:
On the back it says:
Alps Japan RH2701 50KAX2
with terimals are
#1 Ground
#2 Out to amp board
#3 In from sel
#4 NC or Loudness
So if you have it on 4 you will get hum (open connection)
The four pin:
On the back it says:
Alps Japan RH2701 50KAX2
with terimals are
#1 Ground
#2 Out to amp board
#3 In from sel
#4 NC or Loudness
So if you have it on 4 you will get hum (open connection)
OK, well that is how I have it...
RCA input Earth to pot, then from the pot earth connection to the board input ground.
Question though...where should the RCA output ground originate? The way mine is set up it ends up being the same point as where the input ground originates. I started thinking that this may be causing the loop.
It is a 3 pin pot and I have three others to reference so I am sure I am OK there.
I still suspect that it has to do with the output RCA's and the grounding scheme.
RCA input Earth to pot, then from the pot earth connection to the board input ground.
Question though...where should the RCA output ground originate? The way mine is set up it ends up being the same point as where the input ground originates. I started thinking that this may be causing the loop.
It is a 3 pin pot and I have three others to reference so I am sure I am OK there.
I still suspect that it has to do with the output RCA's and the grounding scheme.
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Star earth signal gnd everything to the cathode resistor's ground point to have a visually clean earth reference node, could be one idea.
OK, one more update.
I am using Broskies PS-1 for the PSU which has regulated B+ and heater supply. I originally had the heaters set up for series but last night I changed them to parallel.
I ran the RCA ouput ground to the ground on my PCB and the RCA output signal to the signal output and nothing but terrible hummm.
THEN I swapped ouput wires, PCB ground to RCA signal output and PCB signal output to RCA ground and IT MADE LOVELY MUSIC...for about 40 seconds...then the terrible hummm returned. UGHHH!!!!
This one is really stumping me...
I am using Broskies PS-1 for the PSU which has regulated B+ and heater supply. I originally had the heaters set up for series but last night I changed them to parallel.
I ran the RCA ouput ground to the ground on my PCB and the RCA output signal to the signal output and nothing but terrible hummm.
THEN I swapped ouput wires, PCB ground to RCA signal output and PCB signal output to RCA ground and IT MADE LOVELY MUSIC...for about 40 seconds...then the terrible hummm returned. UGHHH!!!!
This one is really stumping me...
Attachments
post pics of your amp. It may be a routing/wiring issue. Show the whole amp with pics of each compartment/section. May be good idea to look at your amp and draw diagram/ schematic. Sometimes in drawing it yourself, you can see where you made an error.
keep power supply wires away from signal wire
amp board and supply board should shift/change place
amp board and supply board should shift/change place
yup...rearranged to this and did two more things...
1. tried a toroid just to rule out xformer noise
2. yanked out the rca outputs from the chassis
with the toroid the hum comes on immediately and is even louder.
After I rearranged it with the EI core xformer it came on and played nicely for about a minute and then the humm came back. Thats when I tried the toroid.
So I am at a total loss here...I even threw in a pair of EL34's again to rule out the tubes...and same thing...hummmmmmmmm
I am about ready to throw in the towel on this one...
1. tried a toroid just to rule out xformer noise
2. yanked out the rca outputs from the chassis
with the toroid the hum comes on immediately and is even louder.
After I rearranged it with the EI core xformer it came on and played nicely for about a minute and then the humm came back. Thats when I tried the toroid.
So I am at a total loss here...I even threw in a pair of EL34's again to rule out the tubes...and same thing...hummmmmmmmm
I am about ready to throw in the towel on this one...
Its either you got something traced totally wrong regarding the audio schematic on PCB or you get a strong oscillation, which sounds like hum if high amplitude. Maybe that is why it comes and goes. In an open loop pre with a reg you can either get it from the interaction with the reg, or with the signal run and the grid. Are there 1K grid stoppers tightly soldered to the grid pins? I suggest you hard wire it.
should I try and increase the grid stopper value to 1.5K or 2K maybe?
I triple checked the board traces and they are correct...the 1K grid stoppers are very close to the pin 5 on both channels.
I triple checked the board traces and they are correct...the 1K grid stoppers are very close to the pin 5 on both channels.
If you got one, set it to AC input and check the B+ line at 5mV and 50uSec. If it ain't a horizontal line, but its a sine or a thick mess, its power line oscillation. If you have not got a scope its difficult to know. I would start by twisting B+ GND wires. Are the ''triodizing'' resistors tight for pins 3,4? Larger grid resistors I doubt they would change something.
And they did not...I tried 1.5K and 2.1K and same result.
I think that for the principle of the matter I will P2P this I just need to reorder some resistors. I have all the other stuff.
I cant believe that 2 different PSU's I use on 2 other amps I have are that noisy. It must be something in the layout of my PCB.
I think that for the principle of the matter I will P2P this I just need to reorder some resistors. I have all the other stuff.
I cant believe that 2 different PSU's I use on 2 other amps I have are that noisy. It must be something in the layout of my PCB.