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PostPosted: Wed Sep 09, 2009 8:15 pm 
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Holy Ghost
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VRM is our "Voltage Regulation Module" kit based on the VVR design but modified to minimize voltage drop. Technically it is simply a variable B+ voltage control.

It is designed to reduce the power level of your amp while retaining the sound. Essentially, you get very close to the same sound at a lower volume. The tiny board size means silent operation and should fit anywhere in your Trinity Amp.

Specs:
Board size approx 1.25" sq.
B+ Voltage drop 2.7V @ 100 ma
Current limited at 230ma
7A MOSFET device mounted on PCB or remote
Simple connections required - B+ line in, B+ line out, ground.

Replace the power switch in your amp with the "switched" control pot VRM kit for $40 plus $8 shipping in North America and $15 shipped elsewhere. . Kit include all parts: PCB, 1M switched control pot/knob and 2 DC blocking caps to be used on the first tube grids. Make a few connections and you're ready to go.

Attachment:
VRM_IMG_2611.JPG
VRM_IMG_2611.JPG [ 395.4 KiB | Viewed 18185 times ]


More application info here: http://www.trinityamps.com/phpbb/viewtopic.php?t=1176

To order one, please email me.

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PostPosted: Sat Oct 24, 2009 11:17 am 
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Location: London, Ontario
I've come late to the party, having only just heard about Trinity.

However, I went on a similar journey a couple of years ago, after building a 5E3 from a Marsh kit. Out of the box, it was louder than expected, and without the early breakup it was supposed to have.

I eventually had to face facts- the kit's Mojo PT had way too much output. B+ readings with the stock circuitry and a Sovtek rectifier were around 425-430V. As I discovered, there's only so much you can do with rectifier swaps and rebiasing. After I got down to about 370V, anything I did to drive the B+ lower, just made the amp sound worse.

In order to get the B+ below 350V with normal component values, I eventually bought a Mission PT. The amp now works the way it's supposed to, and has become my desert island amp.

I'd still like a low-power switch, though, and the VRM looks interesting. But based on past experiments, I wouldn't have expected a 1V change to make much difference in output.

Is that all the voltage reduction the VRM produces, or does the B+ continue to drop as you rotate the knob?


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PostPosted: Sat Oct 24, 2009 12:17 pm 
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Holy Ghost
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Welcome to the party!

steve_rolfeca wrote:
I'd still like a low-power switch, though, and the VRM looks interesting. But based on past experiments, I wouldn't have expected a 1V change to make much difference in output.


The VRM drops a few volts from B+ when it's set to Max. Some designes were dropping 10 -20 Volts which wasnt acceptable.


steve_rolfeca wrote:
Is that all the voltage reduction the VRM produces, or does the B+ continue to drop as you rotate the knob?


As you rotate the control knob, the B+ continues to drop to below 100V [this is adjustable BTW] so you have complete control of the B+ from max B+ in you amp to a minimum that you can actually set.

It works very well.

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PostPosted: Wed Nov 04, 2009 11:31 am 
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Location: London, Ontario
Thanks for the mod!

I fired it up for the first time last night, and it's working a treat in my 5E3.

Even at high levels of voltage reduction, I couldn't detect a noticeable difference in the operating temperature of the amp.

At small to medium levels of reduction, the tone change was much less than I've experienced with power soaks or master volume controls. Being able to dial in a specific amount of reduction makes more sense to me than using a "half-power" switch.

Although the tonal side-effects were more noticeable at higher reduction levels, slight adjustments of the single tone control on the 5E3 were all it took to make the results quite useable. More than useable, in fact- some of the low-level tones are downright addictive.

My expectations were fairly high going in, yet I still got more out of this mod than I was hoping for...


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PostPosted: Thu Mar 04, 2010 10:33 pm 
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id like to order a vrm cant find ordering info mark


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PostPosted: Fri Mar 05, 2010 12:03 am 
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Holy Ghost
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mark enger wrote:
id like to order a vrm cant find ordering info mark


email me & I'll take care of it.

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PostPosted: Tue Apr 13, 2010 3:15 pm 
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Holy Ghost
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updated topic

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PostPosted: Sun Dec 05, 2010 3:46 pm 
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Holy Ghost
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updated pricing and shipping options

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PostPosted: Sun Feb 13, 2011 10:20 pm 
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I installed one of these in my Trinity Deluxe yesterday and I can vouch that it does a fantastic job of lowering the volume while retaining the tone. Best $35 you can spend on an amp mod. There is very little heat produced; even at maximum B+ reduction. My favorite setting right now is with the knob at about 12 o'clock; the tone is still there while the volume is knocked down to home use levels.


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PostPosted: Sun Mar 06, 2011 1:25 pm 
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Holy Ghost
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Change in spec for VRM. Knob detail added.

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PostPosted: Thu Sep 17, 2015 1:52 pm 
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Can these still be purchased?


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PostPosted: Thu Sep 17, 2015 4:21 pm 
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Holy Ghost
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LedZepp007 wrote:
Can these still be purchased?


Yes, $40 USD for the kit of parts, $8 shipping in N. America

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PostPosted: Thu Oct 15, 2015 12:34 pm 
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Hi, I have one if these left over from a build i did a while ago. I'd like to add it to a JTM45 that I've since built. Will it be able to handle the extra power of the JTM45?


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PostPosted: Fri Oct 16, 2015 8:58 am 
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Holy Ghost
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The VRM will not work ona fixed bias amp. It is for Cathodebias only, up to 40W

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