A couple newbie questions

redplater · 23rd November 2010, 10:34 PM

I'm in the process of gathering parts for my first stereo amp. I've built a good number (say 20) guitar amps. However, I have a concern about grounding issues. My plan is to build a preamp and two monoblocks. If I use three prong plugs on each piece of equipment and then shielded cables running back and forth from the preamp to the monoblocks....isn't that going to create ground loops? What can I do (ahead of time) to prevent and/or reduce the possibility of ground loops.

Question number 2...

One of the rules among guitar amp builder is to put the transformers as far apart as possible. However, I see home-built and commercial amps with the transformers REALLY close together. Granted the laminations are oriented at 90 degrees, but close. Do I need to worry about the OT picking up any interference from the PT?

Thanks!

aardvarkash10 · 23rd November 2010, 10:52 PM

For #1, read this and this

c2cthomas · 23rd November 2010, 11:05 PM

Thanks for that aardvarkash10 - verrrrrrry nice!

aardvarkash10 · 23rd November 2010, 11:27 PM

don't thank me - I'm just the freeloader who knows where to look! The authors are the good guys here - and both of these authors have done lots in the field for our community

redplater · 23rd November 2010, 11:34 PM

Thanks! ...and knowing where to look is 99.9% of the battle!! I appreciate the head's up!

DF96 · 24th November 2010, 10:43 AM

Interference between transformers is always possible, but 90 deg orientation helps a great deal. Stereo OPTs are generally higher quality than guitar OPT, so may have less stray field/pickup.

The fact that you have asked this question shows that you are already thinking about the right issues. One big difference between stereo amps and many guitar amps is that stability is achieved by careful layout and screening, rather than huge grid stoppers.

23rd November 2010, 10:52 PM	#2
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	For #1, read this and this __________________ Yes, conservatism thrives on low intelligence and poor information. But the liberals in politics... continue to back off, yielding to the supremacy of the stupid. It's turkeys all the way down. - George Monbiot, guardian.co.uk, 6 Feb 2012

23rd November 2010, 11:05 PM	#3
c2cthomas 49 - for the 16th time diyAudio Member Join Date: Oct 2006 Location: Near "Music City" (Nashville Tennessee)	Thanks for that aardvarkash10 - verrrrrrry nice! __________________ "You can't always get what you want" K. Richards/M. Jagger *** "Next time I will know some things better" Zen Mod

23rd November 2010, 11:27 PM	#4
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	don't thank me - I'm just the freeloader who knows where to look! The authors are the good guys here - and both of these authors have done lots in the field for our community __________________ Yes, conservatism thrives on low intelligence and poor information. But the liberals in politics... continue to back off, yielding to the supremacy of the stupid. It's turkeys all the way down. - George Monbiot, guardian.co.uk, 6 Feb 2012

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23rd November 2010, 10:34 PM	#1
redplater diyAudio Member Join Date: Nov 2010	A couple newbie questions I'm in the process of gathering parts for my first stereo amp. I've built a good number (say 20) guitar amps. However, I have a concern about grounding issues. My plan is to build a preamp and two monoblocks. If I use three prong plugs on each piece of equipment and then shielded cables running back and forth from the preamp to the monoblocks....isn't that going to create ground loops? What can I do (ahead of time) to prevent and/or reduce the possibility of ground loops. Question number 2... One of the rules among guitar amp builder is to put the transformers as far apart as possible. However, I see home-built and commercial amps with the transformers REALLY close together. Granted the laminations are oriented at 90 degrees, but close. Do I need to worry about the OT picking up any interference from the PT? Thanks!

23rd November 2010, 11:34 PM	#5
redplater diyAudio Member Join Date: Nov 2010	Thanks! ...and knowing where to look is 99.9% of the battle!! I appreciate the head's up!

24th November 2010, 10:43 AM	#6
DF96 diyAudio Member Join Date: May 2007	Interference between transformers is always possible, but 90 deg orientation helps a great deal. Stereo OPTs are generally higher quality than guitar OPT, so may have less stray field/pickup. The fact that you have asked this question shows that you are already thinking about the right issues. One big difference between stereo amps and many guitar amps is that stability is achieved by careful layout and screening, rather than huge grid stoppers.

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