Another 12xxx New Build

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emmjaydubya
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Re: Another 12xxx New Build

Post by emmjaydubya » Mon Mar 18, 2013 10:42 pm

I know what you mean about the waiting game, but his stuff is pretty great.

As far as masters go, the PPIMV seems to be the most popular. Here is the Lar/Mar PPIMV on the Metro wiki:

http://metroamp.com/wiki/index.php/Lar/Mar_PPI-MV

And Valvestorm sells the parts:

http://valvestorm.com/Amp%20Mods/LarMar

I couldn't say from experience though, I'm running a variac, a reactive speaker-motor load and eventually an attenuator.

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vanhalen5150
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Re: Another 12xxx New Build

Post by vanhalen5150 » Wed Mar 27, 2013 12:03 pm

Personally I'd get your amp up and running as a stock amp first before adding an MV into the intial build mix. Make sure it works as an amp first. You could save yourself a lot of potential headache if you do.
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JimiJames
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Re: Another 12xxx New Build

Post by JimiJames » Fri Mar 29, 2013 11:59 am

HUGE +1

Then... Try 'em both... I went with the Metro PPIMV (in my '69 not 12) and routed the MV in front to the Presence and moved the Presence to the backside - speaker jack. All this was possible with Larry's grounding scheme. :thumbsup:
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YMI5150?
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Re: Another 12xxx New Build

Post by YMI5150? » Mon Apr 01, 2013 1:18 pm

Heaters could use another twist. a bit loose.

get an attenuator and blow off the master volume.

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neikeel
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Re: Another 12xxx New Build

Post by neikeel » Mon Apr 01, 2013 3:54 pm

YMI5150? wrote:Heaters could use another twist. a bit loose.
I disagree!

3 even full 90 degree twists per inch is the correct number, more than that you risk overtightening the wires, damaging the strands and weakening the insulation, there is absolutely no benefit to be had from more than that.

They could be more even for sure :wink:
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vanhalen5150
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Re: Another 12xxx New Build

Post by vanhalen5150 » Mon Apr 15, 2013 8:04 am

neikeel wrote:
YMI5150? wrote:Heaters could use another twist. a bit loose.
I disagree!

3 even full 90 degree twists per inch is the correct number, more than that you risk overtightening the wires, damaging the strands and weakening the insulation, there is absolutely no benefit to be had from more than that.

They could be more even for sure :wink:
I disagree! :P

I've twisted full 4 foot lengths the modern wire 22awg wire with a power drill , then cut off 4'' from both ends and stripped the entire lengths. Not a single strand of wire was broken. Insulation was still adhered to the wire as well.

I think the older type of wire this would happen but the new stuff seems to be pretty strong to tourque force.

Doesn't look vintage but unless all the other parts are as well...
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Re: Another 12xxx New Build

Post by julkke » Mon Apr 15, 2013 8:21 am

I think many people overdo the heaters. Many 70s marshalls didn't even have twisted heaters and still didn't hum that bad.

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vanhalen5150
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Re: Another 12xxx New Build

Post by vanhalen5150 » Mon Apr 15, 2013 8:40 am

I agree. Grounding is where a lot of your amp noise is coming from anyways.
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JimiJames
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Re: Another 12xxx New Build

Post by JimiJames » Mon Apr 15, 2013 2:27 pm

I do a 3 wrapper.
vanhalen5150 wrote:...I've twisted full 4 foot lengths the modern wire 22awg wire with a power drill...
...Doesn't look vintage but unless all the other parts are as well...
I thought I was slick until I got yelled at for doing that on my 12001... :?
yea, I guess you could do it (modern) anyway you want.. others do it in their other type builds, but I wouldn't do it !
and it does look neat & all, and with the new polymers the insulation has the elasticity and likely to resist dry-rotting over a longer period of time I would think.

Larry's grounding scheme. Doesn't get any better.
RIP Mark Abrahamian-rockstah -classmate/roommate
RIP Ben Wise -StuntDouble- comrade-in-arms

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