Buzz in gainclone, looking for source.

[MikeBettinger]

Originally posted by AndrewT
Hi Mike,
bypassing is a different issue again.

By bypassing I mean the tiny fast caps used to attenuate voltage glitches due to current changes in high current devices.
These bypass caps should be inserted into the circuit to bypass the current spike back into the device and do not need to be returned to the ground.

Hi Andrew,

I took my time reading this one and have deduced that you use the term bypassing to describe, for example, the caps placed across a rectifier diode; where as, I,m using it a bit more broadly I guess. It all works out when the power is applied...

I do have a real question. Has there been any discussion of grounding on this site. Not the hear-say type discussion, but I'm interested in reading any discussion (or links) based on theory or application. I've tried the site search approach and I don't have that much time or patience.

My interest in this is based on trying to understand where the various approaches illustrated here came from and the logic behind them. It's a topic I've been interested in for years and my curiousity is curious since there is a bit of a disconnect between my way and what's being shown here.

Regards, Mike.

[AndrewT]

Hi,
I slowly gleaned the titbits that finally explained how to do it correctly.
D. Self tells you how to connect it and in hindsight what he wrote is correct, but i still did not understand the how until this Forum showed me the way and why.

I cannot point you to a definitive article, sorry.

What has really surprised me are the number of commercial amps that get it wrong. I expected the professionals to be right.

There is one final question I have not fathomed out yet.
Where is the BEST place to make the safety earth connection to the grounding system?

Self says at the RCA input ground but gives other locations as well.
What if the amp is multi-channel? I'll keep reading and maybe experimenting.

I have started using snubbers across the bridge diode instead of caps alone. See what this Forum does to you. But I don't yet know if they help the sound or the measurements.

[diarav]

Hi,

I am also trying to understand grounding, preventing hum etc, and a search on these forums will bring up all these posts. Most of the users have similar problems and the experts always provide the same advice.

I think it's time we had a "sticky" post covering all aspects of the "rules" of grounding , twisted cables, sources, Cap. done by the experts.

This will help beginners use this info and also help others link to this post easily.

Just a suggestion !

Regards
Din

[kmj]

and a great suggestion it is.

[AndrewT]

Hi,
I perceive a problem.

Not everyone agrees.

My experience only applies to UK grid conditions and UK approved sources.

A "not quite right" power amp will tolerate well grounded sources.
The problem gets worse when some of the ancilliaries break the rules.

[kmj]

Hey, guys!
I thought that the speakerground (return) was considered dirty and should be placed at the powerground (as I have done), should I perhaps move it to the audioground?

The reason I ask is that I found this post.

I could ofcourse just try it but it's always nice to hear comments also.

[kmj]

Perliminary tests indicate that the buzz is gone, or at least reduced.

I started by separating the groundwires connecting the two channels together in the safetyearth. This didn't help so I removed them altogether and this seems to have solved it. I need to test some more to be sure thou.

European contries have 220V mains and usualy a three pronged socket containing Live, Neutral and Earth. Sweden also has this but in apartmentbuildings these are usualy only present in the kitchen due to the proximity of running water. In the other rooms there are only two pongs and because of this and the fact that my casing is entirely made of wood it should be ok, am I right? (sure hope so...)

[kvholio]

my casing is entirely made of wood

Not entirely, KMJ.

What will happen if the Live wire of your AC-mains touches your amplifier-ground (0v) and you touch the RCA inputs ?


If you use a disconnecting-network between amplifier-ground (0v) and safety-earth this kind of fault will trip your amplifiers' main fuse, or the fuse from your ac-mains supply.
Stay safe.

With kind regards,

Klaas

[kmj]

If you use a disconnecting-network between amplifier-ground (0v) and safety-earth this kind of fault will trip your amplifiers' main fuse, or the fuse from your ac-mains supply.
Stay safe.

I think that I need some terms defined.

Signalground is the, yeah. Signal ground
Amplifierground? That's the one I refered to as Powerground, right?
That's the one that has a direct connection to the transformer so I guess that's the one. But what good will it do to connect ANYTHING between this point and the safety-earth? The safety-earth doesn't connect to anything at all, how could this possibly blow a fuse? I must clearly be missing something vital.

[kmj]

For the disconnecting network you refer to is one like the one illustrated on this picture, right?



In that case the network would only be connected on one side since the Earth (ground) prong in the socket isn't connected to anything. The inlet on the amp has three prongs, the powercord and plug has three but the socket in the was only have two. Live and neutral.