Help Implementing Star/Larry Grounding scheme

Get support and show off your MetroAmp JTM 45 kit builds.

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Roe
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Re: Help Implementing Star/Larry Grounding scheme

Post by Roe » Wed Aug 11, 2010 2:10 pm

pvan339 wrote:If the bus wire is not soldered to the back of the pots with the Star/Larry grounding system, does the back of the treble and bass pot need anything done to them?
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Re: Help Implementing Star/Larry Grounding scheme

Post by chetz » Sat Jan 01, 2011 8:24 pm

wildebassman wrote:Hi mate!

"but the point is to have the loops spread out, and be as close to a line in their positioning as possible."

Cheers,

Dennis.
A ground wire is coming off the back of the PI and is being grounded at point #3. Does that wire come off the negative terminal on the PI? Just want to make sure.

Got this project geared up again! Thanks for the help.

Jeff

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Re: Help Implementing Star/Larry Grounding scheme

Post by Xplorer » Fri Jul 13, 2012 10:06 am

Hi !
i'm about to build two JTM45/100 and another superlead69.

about the JTM45/100, i'm still a bit uncomfortable in my understanding of the larry's grounding. I'd be affraid to do some mistakes. Did anybody create a layout, applied to this specific amp ?
i'm thinking of doing this, based on Billy batz's layout, so i'd just have to make sure it's ok, and then follow the design while building it.
thanks for this topic.

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Re: Help Implementing Star/Larry Grounding scheme

Post by hotguit » Fri Jul 26, 2013 6:01 am

HI
I'm going to rewire my jmp '78 2204, which is very noisy, according to Larry's grounding scheme.
But I'm a bit confused; must not the sub stars points be linked togheter by a ground bus which IS ISOLATED by chassis and goes to ground in ONE POINT ONLY (at input jack)??? (SEE ATTACHEMENT)
In the pics of jtm 45 ground scheme each cap goes to ground in its own point; is it right? in it an alternative way of doing the grounding or what?
Who can explain me?
Thank you so much
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Re: Help Implementing Star/Larry Grounding scheme

Post by neikeel » Fri Jul 26, 2013 10:32 am

Larry's grounding is not a centralised common earth rail

Each section has its own dedicated earth to the chassis:

Preamp
PI
Screens
Mains
Input etc

Essential that the input ground is dedicated to chassis, nothing else
also the heater centre tap is tied to the guitar input jack ground.

Both those things make the biggest change in my testing.
Neil

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Re: Help Implementing Star/Larry Grounding scheme

Post by hotguit » Sat Jul 27, 2013 10:23 am

Thank you neikeel very very helpful reply
Thank you
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Re: Help Implementing Star/Larry Grounding scheme

Post by hotguit » Sun Aug 04, 2013 11:25 am

Hi nobody has a scheme i can apply to a jmp 2204?
thank you
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Re: Help Implementing Star/Larry Grounding scheme

Post by Wattever » Sat Dec 21, 2013 9:42 pm

I'm FINALLY getting started on assembling my JTM45, and I just have a few things that I want to clarify before I start cutting wires and drilling holes. :scratch:

In the picture way back on page one of this thread, I can see that the new ground wires are added, and the old ones aren't removed, but the input grounds are a bit confusing. I assume, that the "stock" ground wires go to the new #1 ground point, but the picture seems to show the grounds coming off the tip (rear terminal) of the jacks.

Another thing that I'm not sure about, is how to ground the bottom of the cap on the back of the presence pot. Should it "V" back to terminal one on the pot, or to one of the new grounding points? (I would guess it would be #3.)

Aside from those two things, I think it should be reasonably smooth sailing... at least til the smoke starts rolling out of it. :shrug:

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Re: Help Implementing Star/Larry Grounding scheme

Post by frusciante89 » Sun Jan 05, 2014 2:18 pm

Hi guys, I'm almost done with my 1987... I just found out about the Larry grounding, and it's too late to drill holes :/ Can I use the transformers screws and the board screws for the ground lugs? Will there be interferences? Another thing: will the paint on the chassis create problems with grounding? :peace:

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