Commercial Gainclone kit- building instructions

[pmchoong]

i only have this preamp now.....b1 buffer still needs to connect all parts and still no chassis yet.

 

[pmchoong]

if i turn the volume down to zero and put my ears close to the speaker, i can hear music (from the tuner) beyond the buzzing sound...very strange

 

[pmchoong]

buzzing is audible when you put your ears very close to the speaker....say about 2-3inch from the speaker and listen hard

 

[diabloid]

Buzzing from ac mains is expected with diode bridge and small filter caps, but once amplifier is connected to load it is not noticeable, when music plays. The only way to make it totally silent: 1. to use car batteries 2. to use regulated power supply.

 

[pmchoong]

you mean
1)the buzzing sound will always be there if you use mains
2)no way to completely eliminate the buzzing unless you use the two options as suggest by you

but i read many people said (in this forum) that it was completely silent....no back ground noise

 

[koogar]

Does the buzzing stop if you lift the earth ?

 

[AndrewT]

once amplifier is connected to load it is not noticeable, The only way to make it totally silent: 1. to use car batteries 2. to use regulated power supply.

no.
Correct wiring and routing of wiring can give a silent power amp output.

 

[pmchoong]

Does the buzzing stop if you lift the earth ?

how do you 'lift the earth'?

 

[pmchoong]

no.
Correct wiring and routing of wiring can give a silent power amp output.

I have a very small chassis (hey...it was free, so no complain) and wires run besides the transformer. Please see picture

 

[Pocoyo]

I have a very small chassis (hey...it was free, so no complain) and wires run besides the transformer. Please see picture

hi

are they from alumunium ?

 

[pmchoong]

yes they are aluminium and metal....i removed the grd wire that connects the main pcb with the chassis and voila...buzzz is gone!
You are not suppose to connect the 'chg' to the chassis!

 

[udailey]

With amplifier on you might try just moving wires around, especially signal wires. My last humm was because an signal gnd wire was real close to a signal wire. When separated it went away.
Uriah

 

[pmchoong]

now to test the other channel

 

[pmchoong]

works fine as well...again without connecting 'chg' to the chassis...thank you everybody.....i love you guys.....you guys are really great

 

[udailey]

Group hug! LOL

 

[koogar]

how do you 'lift the earth'?

if the buzz has gone when the earth or the chassis ground is disconnected you could try a large 10 ohm resistor from the chassis ground to the case that will also stop the buzz but still ground the boards.

i have a good star ground but the PC i use as source is just too noisy this worked for me although i will change it for a CL-60 NTC later. do not interupt the main safety earth from the socket though that should still be connected to the chassis with nothing between it.

 

[pmchoong]

if the buzz has gone when the earth or the chassis ground is disconnected you could try a large 10 ohm resistor from the chassis ground to the case that will also stop the buzz but still ground the boards.

Hi...thanks. The boards sits basically on the anodized heatsink and so far, i have not notice the heatsink conducts electricity through the chassis.

The other problem is the LED. On one channel it turned off quite quickly (about 1-2 seconds) while the other took about 2 minutes to turn off. It slowly dims until the light dies off. Why?

 

[pmchoong]

After listening to them for a few hours now....both amps led dies off at approximately 2 minutes. Not a concern?

 

[Nis]

I just finished mine. Surprisingly nothing exploded when I turned it on.

I do get 22mV off set on one channel and ~60mV on the other channel. I se a single transformer (The one from Poland recommended in this thread) and no pot.

Should I be worried about the difference in offsets?

 

[koogar]

I just finished mine. Surprisingly nothing exploded when I turned it on.

I do get 22mV off set on one channel and ~60mV on the other channel. I se a single transformer (The one from Poland recommended in this thread) and no pot.

Should I be worried about the difference in offsets?

nope the offset in everychip is very random only way to get 2 the same is to buy alot and test each one and pair them up as close as you can .

those numbers look fine and the offset can be + or - mV