My 50W Build! (with pics) - COMPLETE!!!

Get support and show off your MetroAmp 50 Watt kit builds.

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mwm523
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My 50W Build! (with pics) - COMPLETE!!!

Post by mwm523 » Sat Nov 17, 2007 10:25 am

Hey all, I received my 50W kit yesterday, and got started building last night after work. Here are some pics of my progress so far.

Chassis, transformers, choke ready for installation:
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Lots of parts! :shock:
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Transformers, choke, tube sockets, and cap cans mounted:
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Whew! Heaters done:
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Rectifier bridge and mains fuse mounted, 220V and 240V leads cut and heat shrinked, PT wiring continued:
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Switches mounted, PT wiring complete:
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OT primary and secondary wires routed, impedance switch installed, 1ohm bias resistors installed:
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Screen resistors, indicator, and output jack installed (I will only have one, the other hole will have a PPIMV):
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So I'm through step 11 so far. I'll be picking it up at step 12 today. 8)
Last edited by mwm523 on Sun Nov 18, 2007 10:52 pm, edited 1 time in total.
-Mike

philip
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Post by philip » Sat Nov 17, 2007 10:30 am

nice!!

looks very clean. And although I'm having 2 reissues ATM, seeing these pics makes me want to get a kit and build one too %)

keep the photos coming and don't forget a soundclip when you're done =)

\m/

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el34on11
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Post by el34on11 » Sat Nov 17, 2007 11:39 am

Very Nice work so far..... 8)

Love the second pic with all the goodies layed out like that :)

Derrick
LesPauls and Marshall's

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Scumback Speakers
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Post by Scumback Speakers » Sat Nov 17, 2007 11:40 am

Nicely done. If the Gods of shipping are with you, a couple of H75's should be at your door on Tuesday or Wednesday... :)

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mwm523
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Post by mwm523 » Sat Nov 17, 2007 12:45 pm

Southbay Ampworks wrote:If the Gods of shipping are with you, a couple of H75's should be at your door on Tuesday or Wednesday... :)
Jim, that's awesome. Thanks for the great service! 8)
-Mike

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Post by thousandshirts » Sat Nov 17, 2007 2:59 pm

Nice. Looks very similar to the instruction manual!

Will

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rockstah
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Post by rockstah » Sat Nov 17, 2007 3:22 pm

looking good. what kind of resistors are on the output tubes to ground?

OnTheFritz
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Post by OnTheFritz » Sat Nov 17, 2007 3:58 pm

rockstah wrote:looking good. what kind of resistors are on the output tubes to ground?
Yeah, those don't look like the metal oxide 1 ohm resistors I've used from Metro.
"I don't like country music, but I don't mean to denigrate those who do. And for the people who like country music, denigrate means 'put down' " - Bob Newhart

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mwm523
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Post by mwm523 » Sat Nov 17, 2007 4:16 pm

rockstah wrote:looking good. what kind of resistors are on the output tubes to ground?
Thanks Mark.

According to the parts list/instructions, they are 1 ohm 1 watt metal film. They're the exact same ones that came in my JTM 45 kit.
-Mike

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mwm523
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Post by mwm523 » Sat Nov 17, 2007 5:47 pm

Update... Things are moving along nicely. Here are some more pics.

Pots mounted:
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Ground bus installed:
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Input jacks mounted:
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Close-up of the jacks:
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Close-up of the output jack and impedance switch:
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Close-up of the output tube sockets w/ 1ohm bias resistors to ground:
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V2 plate resistor:
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Board mounting bolts installed and board sitting in there:
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Board bus wires:
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One side of the board wiring:
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Both sides of the board wiring (Notice the missing orange/green twisted pair. No need for those since the amp will have a PPIMV):
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Close-up of the filter caps:
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Board installed. Next step is to cut/route/attach all the wires coming from the board:
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I have to replace that white wire at the bottom-right corner of the board, it's too short. Needs to go to the rectifier bridge.

Started to get tired, so I'm taking a break for a while. I'll probably do some more tonight.
-Mike

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Post by OnTheFritz » Sat Nov 17, 2007 6:41 pm

Looking awesome! 8)
"I don't like country music, but I don't mean to denigrate those who do. And for the people who like country music, denigrate means 'put down' " - Bob Newhart

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Post by Smokin Tone » Sat Nov 17, 2007 10:03 pm

Very nice work. Looking good.

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Post by toner » Sat Nov 17, 2007 10:27 pm

mwm523,
Nice work. It's great that guys like you take the time to share your builds. It will help a lot of people, even though the 50w instructions are excellent.

myfoot

Post by myfoot » Sun Nov 18, 2007 7:36 am

Man this is killing me. I"m waiting for my son to come home from school for thanksgiving to start building .Nicely done so far.I"m also planning on putting the PPIMV in this one so I'm watching closely :P

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mwm523
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Post by mwm523 » Sun Nov 18, 2007 10:52 pm

OK, I'm done!!!! :D

I put in a few more hours Saturday night, until I just couldn't do any more... Then I picked it up Sunday afternoon, and finished up.

More pics...

Working on the pot wires from the bottom of the board:
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Preamp tubes wired up:
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Board patially populated:
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That's where I ran out of steam Saturday night, and went to bed. It was like 2:00am and I was exhausted.

Sunday morning I spent hanging out with the family, and then started up again after lunch.

Ok, here we go, the home stretch!
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Finished populating the board:
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Bias circuit with bias adjustment pot mounted on the board (Yes, I took care of that unsoldered turret between the 2 .022uf Sozos :shock: ):
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Power cable and PPIMV installed... HEY! I THINK I'M DONE!!!!!
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PPIMV dual 250K pot:
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Close-up of PPIMV shielded wiring connected to the board:
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PPIMV wiring:
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V5 grid stopper resistor on pin 5, connected to PPIMV shielded wire:
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V4 grid stopper resistor on pin 5, connected to PPIMV shielded wire:
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One last PPIMV shot:
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Full chassis shot:
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Another full chassis shot:
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Rear:
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Tubes:
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I have Mullard reissue EL34's for power, and the pre's are a NOS Mullard in V1, a NOS Amperex Bugle Boy in V2, and an old Silvertone in V3 (which I think is also an Amperex, it says made in Holland)

Head:
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Group shot with its little brother (JTM 45) on the left and my Les Paul:
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Testing went very smoothly, all my voltages were right where they should be. I had one head scratching moment on page 26 (Testing Part 1) where it said I should have about 450V DC on the positive terminal of the bridge rectifier, but I was only reading 315V DC. The directions should have said to turn the standby switch on and THEN take that measurement. Once I did that I got 470V DC.

Everything else was right in range, so I installed my tubes and continued on. Installed the pre's first and took measurements, then installed the output tubes, hooked up a speaker cab and measured again. All looking good, and normal light hiss from the speakers when turning up either volume pot.

Then I set the bias. My B+ voltage is 449V, so I biased the amp at 39mA (70% plate dissipation). My tubes are pretty closely matched, only off by about 2mA.

So now it was time to fire it up and plug in the Les Paul!!! I have to say that I IMMEDIATELY fell in love with the tone of this amp. The clarity, the punch, the sustain, the harmonics, the controlled feedback, I am in tone heaven!! I get a nice crunch and singing sustain starting between 6 and 7 on volume 1, and its sweet spot seems to be about 7.5 - 8.

I built a JTM 45 kit a few months ago, and I have grown to love that amp. But the point is, I had to grow to love it over the course of a couple of months, making modifications, finding ways to tame the fizz, etc.

This 50W kit just floored me right out of the gate. I'm getting sounds I have been wishing I could get from the JTM, but the JTM is just a different animal. It definitely has its place though, especially for playing bluesy stuff. The 50W is a ROCK amp.

With the Les Paul, I'm getting Cream, Free, Allmans, Zeppelin, all the classic plexi tones. I plugged in the Strat, and while I still have some tweaking to do, I was definitely getting into Hendrix territory.

The only thing I'm considering changing so far on the 50W is the value of the bright cap on the channel 1 volume pot. I've got a 250pf there right now and it has a slight case of ice pick-y-ness at lower volumes (stock value is 500pf, I think that would make my ears bleed :lol: ). I think I'll try a 100pf there, that's what I have in the JTM.

Hope you all enjoyed my build, I know I did! (I am enjoying playing it too!!!!!!) :D :D :D :D

George, this kit is a HOME RUN. 8)
Last edited by mwm523 on Mon Nov 19, 2007 5:38 pm, edited 1 time in total.
-Mike

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