BrianGT, first timer w/ radio (accidentally)

[edjosh23]

This afternoon I completed my Gainclone, this was a first for me doing anything diy besides installing car audio. So far the SQ is "ok" its worse than my Denon but I still have many more hours until I can accutately compare SQ. There is quite a bit of interference, but there wont be as much when the box is complete. One problem I have and I saw someone else had this problem was I can hear the radio when volume is low.

I'm very proud of my amp just waiting for better SQ.

I was told a good way to speed up burn in was turn up the volume, I did so with a dummy 8 ohm load for about 10 min and then stopped because I wanted to hear some music.

Any other suggestions for speeding up burn in?

Right now i have the dummy load on with volume up all the way, and somehow the music from the cd player connected to the amp is playing through the terminals?? What? How is this possible?

I'm going to add pics.




Thanks,

Josh

[karma]

not sure burning it in will get rid of the radio waves. make sure your input wires are properly grounded. and you are using a good
set of rcas for starts.

add pics?

[edjosh23]

The RCAs are dayton's from PE. My hum is louder with the input disconnected. I decreased some hum just by pulling the rectifier back, this definately is not my final chasis and the rectifier and toroid will have a seperate compartment.

I'm gonna shorten the signal path to my pot also.

Here is a pic of the back with RCA wires connected.

And I just wired my led in my on/off rocker



Here is a link to the RCA, JoshHere
I would think they would be good enough? What else can cause radio interference?

Thanks,

[karma]

weird pics still not showing up just a white box with a red x

[edjosh23]

White box with a red x?

[edjosh23]

Also I wanted to know of my current ground scheme is ok. I have 8 awg ground wire with a male disconnect, and the 2 channel ground from the PCBs are combined into a female disconnect. Is that ok? When I disconnect my grounds I seemed to have a hum still, that was just as loud.

Please post some suggestions for everything that you think would help.

Thanks,

Josh

[chipco3434]

Today I fixed a noisy BrainGT gainclone. It's all in the grounding.

Following Nuuk's site, run a 100R/.22uF between chassis star ground and the mains ground wire. Additonally, place a 220pF across the input signal and ground. Right across the tabs. Separate the power and chasis ground stuff from the input grounds, then bind them with a very small wire.

My results were PERFECT! I had the volume pot cranked all the way and not a sound.

Nuuk's Decibel Dungeon

[Greg Erskine]

Hi chipco3434 and edjosh23,

I recommend following Brian's instructions on earthing and not use a star earth. This PCB effectively has the a star earth on each PCB.

I initially had my BrianGT GC wired with a star earth and it hummed, when I rewired it as per instructions it was dead quite. BTW: I didn't connect CHG.

[edjosh23]

I disconnected my CHG, I still have a hum, could it be RFI? I have a wooden case, The finished case will be lined with copper and grounded and should be able to decrease RFI, but can RFI cause static or hum, or the radio interference?

My ground is 8 awg from AC outlet to a disconnect, and then the other disconnect connected 2 it is both CHG which are 16 awg each.

here is a pic of the connection

[BlackDog]

Originally posted by edjosh23
I disconnected my CHG, I still have a hum, could it be RFI? I have a wooden case, The finished case will be lined with copper and grounded and should be able to decrease RFI, but can RFI cause static or hum, or the radio interference?

Hum and RFI are two differents problems:

Hum is normally solved by changing the earthing / star ground arrangements.

Your unintentional radio receiver can be solved quite easily. I tend to get a similar problem where I live, as I'm right next to the regional radio transmitter. Try soldering a 220pF ceramic capacitor across the chips inputs pins, as close to the chip as possible - on my BrianGT clones, I soldered them to the underside of the PCB. This should get rid of that radio!

Steve