100W Superlead Plexi - BUILD DIARY

[mad-axeman]

Hey all,

I thought it would be cool to fully document my Metro amp build, for a few reasons. First off, I thought this could be a valuable resource to those contemplating their own builds. Secondly, I could document any troubles that I have, to prevent others from experiencing the same difficulties. Lastly, this will be an interesting diary of my first amp build.

I plan to take a lot of time on this build, because I want to come away with a greater understanding of the theory involved, as well as a great sounding amp.

My order looked like this:

100 Watt Plexi Amplifier Complete Kit
* Specs - Superlead
* Head Case - Red
* Signal Capacitors - SoZo Mustard +
* Tubes - Mullard reissue EL34 and 12AX7
* Transformers - Metroamp 1203-80-MS, C1998
Lar/Mar PPI MV Kit (will wait to install this until kit is fully functional)


So I'll start with the brown truck dropping me off a package yesterday. The kit came extremely well packaged, and the red headcase looks even better in person (just as George said it would ). Here are photos from the initial unpacking....



UNPACKED:



PARTS SORTED:



TRANSFORMERS/CHOKE BOLTED DOWN/AMP CRADLE/WORK SPACE:






That's all for now. see y'all next time. Please feel free to comment at any time. I would love to hear from the experts and the beginners alike!

[mad-axeman]

Hello!

So, I've gotten a slight bit farther with assembly, and wanted to update. The only issue I had was that I kept breaking the screws in half from over tightening. I really wasn't trying to muscle them, but I obviously was overdoing it.

I was a little concerned about how close the F1 filter cap was in proximity to the choke, as it almost touches in a few places, but I imagine this is a non-issue. As I was working with the electrolytic caps, I noticed that they're made in Taiwan; thinking maybe I should have ordered a different brand....

Here are the latest photos:

[ThunderOne]

Here are a beginners' comments:
Great pics! The ones on the wall too...

I also really dig that red case.

[johnpace2]

Very nice. Thanks for doing this.

Was there an upgrade available for the caps?

[mad-axeman]

Thanks for the interest guys.

Regarding the cap upgrade - there wasn't a particular option to change caps when ordering the kit, but I would think George would have accomodated if I'd have asked. Metro store does offer others, so I would think it wouldn't be a huge deal.

I just finished wiring all the heater wires up, but am not as happy with the quality of the job as I'd like to be, so I'm gonna redo a bit of it before posting any photos. This is important to do cleanly, so I want to do the best I can.

One of the reasons for doing this was to verify the integrity of the instructions/kit, and I have found one discrepency. Namely, in step 5, part F, where you are installing the 1-Ohm metal oxide resistors onto the power tubes. The directions state to route one end thru pin 8 and over to pin 1, "as shown in the photo". However, the photo clearly shows the resistor wire thru pin 1 first, then over to pin 8.

I am thinking that this is not a big issue, and that either way will suffice, but I would like confirmation from anyone that knows. George, are you reading this by chance?

Otherwise, things are going smoothly, and I'll be posting new photos this weekend.

Stu

[ThunderOne]

I'm pretty sure that on my build in progress, I routed the 1 ohm resistor lead through pin one first, then to pin 8. I'd say just do it the way it is shown on the picture.

[mad-axeman]

I'm pretty sure that on my build in progress, I routed the 1 ohm resistor lead through pin one first, then to pin 8. I'd say just do it the way it is shown on the picture.

TO, I appreciate the reply; I went ahead and followed that advice.

Made a bit more wiring progress; unfortunately the brown OT wire was pretty short. Not only was there not enough left over to jumper to the other power tube, there was barely enough to make it to it's own. I just made due the best I could. It doesn't make it all the way to the edge, but hopefully that won't be a problem. Here's what I'm talking about:



Stu

[mad-axeman]

And a few more photos....









Stu

[ThunderOne]

I encountered the same situation. The brown OT primary wire is slightly shorter than it should be and that makes for a tight loop around the V6 tube socket. I also noticed that there wasn't the expected red enamel coating on those wires. I scraped them anyway just in case...
You can see this here even if the impedance selector wires partially block the view.

Metro Superbass OT primary wires.JPG (219.55 KiB) Viewed 5212 times

[mad-axeman]

I encountered the same situation. The brown OT primary wire is slightly shorter than it should be and that makes for a tight loop around the V6 tube socket. I also noticed that there wasn't the expected red enamel coating on those wires. I scraped them anyway just in case...
You can see this here even if the impedance selector wires partially block the view.

TO,

Nice to hear I'm not alone here!

Regarding the "red enamel" - I would have mentioned this if you hadn't. It's always a bit disconcerting when the directions mention that if you don't do something, there will be trouble, yet, you can't find what they're referring to. I'm not sure why it's not there (model/brand specific maybe?), but I really don't think it is. I mean, I didn't notice any difference soldering to it (tinning), as opposed to any other wires. Maybe someone will chime in here?

Stu

[mad-axeman]

[ThunderOne]

Great job, Stu! We appear to be at about the same stage in our builds. As options, I chose Sozo Royal '67 electrolytics, Sozo Vintage Mustards, AB carbon comp resistors and CTS pots for this project. I also routed the back panel for an IEC power cord. I'll show a few pics in a new post.

[mad-axeman]

And here are the latest shots....









Stu

[mad-axeman]

Interestingly, I have been concerned about the degree to which I've twisted my heater wires, thinking that maybe I should have done more. However, I was retubing my Silver Jubilee this afternoon, and was surprised to see how loosely they were done by Marshall.

In general, the wiring doesn't look near as clean as mine, so that put me a bit at ease. I'm sure this comes as no surprise to many, but it does make me feel a bit better.

Stu

[ThunderOne]

Interestingly, I have been concerned about the degree to which I've twisted my heater wires, thinking that maybe I should have done more. However, I was retubing my Silver Jubilee this afternoon, and was surprised to see how loosely they were done by Marshall.

In general, the wiring doesn't look near as clean as mine, so that put me a bit at ease. I'm sure this comes as no surprise to many, but it does make me feel a bit better.

Stu

Don't worry about the quality of your work, Stu! I'm sure that all who have seen your build pics will agree that it's top notch. Also, another thing to keep in mind about wire twisting is that you can overdo it. You might read in some posts about builders who found that out the hard way. The overstrechted wire casing becomes too thin and dries out and after a few years the insulating properties fly out the window. Not good!