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Project Tone Arm modification under scratch guard

Posted: Mon May 25, 2009 9:04 am
by arpsum
Hi all, I'm so sorry not to have posted for a while. Besides, my translation of Vintage Mosrite has not been done yet.

Recently I did the modification of a circuit under a scratch guard. I installed the impedance matching circuit between neck and bridge pickups, and separated the shielding connection from signal ground line. Especially I installed physical hardware against many kinds of noise, such as a brass tube from pickup selector to volume pot, and bolt-on terminals on both pots. In addition to them, I installed rare electric parts such as NOS Centralab's counter-audio tapered pot and NOS capacitors made in 1963.

Tone Arm overview
Tone Arm closeup
Tone Arm inside

Re: Project Tone Arm modification under scratch guard

Posted: Mon May 25, 2009 3:06 pm
by dubtrub
I don't understand the purpose of the modification. What effect does it have?

Beautiful guitar. Could that possibly an Elliott side jack?

Re: Project Tone Arm modification under scratch guard

Posted: Mon May 25, 2009 3:23 pm
by KRamone27
It's got the Vibra Rite base plate so it has to be an Elliot :D

Re: Project Tone Arm modification under scratch guard

Posted: Mon May 25, 2009 4:00 pm
by Veenture
WOW!
That is one clean machine!

Re: Project Tone Arm modification under scratch guard

Posted: Mon May 25, 2009 7:20 pm
by TerryTNM
Boy, that's about the cleanest hookup I've ever seen. Good Job! It looks like it is a noise reduction mod. - Terry

Re: Project Tone Arm modification under scratch guard

Posted: Wed May 27, 2009 1:47 pm
by arpsum
Hi Terry, thank you for your kind help. Yes, this MOD is mainly done for noise reduction. It is so effective that I can hardly hear any noise from the amplifier.

BTW, are you satisfied with a mix sound of neck and bridge pickups? I think almost all Mosrite players prefer bridge pickup sound to neck side, so we tend to ignore a mutual interference of pickups.

As you know, the DC resistance of these pickups are so high, comparison to other passive pickups, that a mutual interference is more serious than any other conventional guitars. When it comes to mix the pickups at center position, the lower resistace device affects negatively against the other one, just like incorrect PA speaker connection.

So I installed the impedance compensator into them with several CR devices. In fact, the two pickups sound so good at any selection.

And you can see the tiny troidal transducer on the pot, this is so called RLC band eliminated circuit instead of usual tone control. Many players rarely make a tone control shut to zero, so I researched the frequency band they really want to control and installed the better circuit.

I'll upload the other image, maybe you can see the detail.

Tone Arm Prototype -Checking physical interference in a control cavity -

Re: Project Tone Arm modification under scratch guard

Posted: Wed May 27, 2009 8:00 pm
by Dennisthe Menace
WoW! That's Incredible Arpsum! Where have you been?!!!??

Re: Project Tone Arm modification under scratch guard

Posted: Sun May 31, 2009 12:52 pm
by Imperial
Hey Gang,

I do not know much about Mosrite's, were they all wired this clean?

This is way beyond guitar porn, this is Michael Angelo type of work.

Re: Project Tone Arm modification under scratch guard

Posted: Mon Jul 06, 2009 3:03 am
by oipunkguy
hey
that's pretty awesome. where in the world did you find these parts? I've looked for centerlab pots, but I came up short. great work by the way.

Re: Project Tone Arm modification under scratch guard

Posted: Mon Jul 06, 2009 5:38 am
by KRamone27
Aaron, I believe that Gibson still uses Centralab pots for their guitars. You might be able to get some of them.