TAD Super Lead 100w - My first build

[Prowler]

Hi!

I'm Andy, 37 year old guitarist from Finland. I started building my own Super Lead on 15.4 2014. It is a Tube Amp Doctor's kit and it is my first amp building project. I've been building a lot of effects pedals before this (about 25) and they all turned out great. I don't know much about amps but I am learning while I'm building it. I know I have to drain the caps before touching anything inside. Maybe i'll take the amp to some experienced builder for the final checks to make sure it is safe to turn it on.

When it's done, I thought of modding it to S.I.R #36 specs so I drilled an extra hole for the fourth pre-amp tube.

Here are some pictures how the work is progressing:

http://1drv.ms/1q6Ipp6

See anything that's not right and needs to be redone? Any tips would be appreciated.

Here are all the documents and instructions that I'm using:

http://1drv.ms/1mRXR7T

I'm working along the steps that are presented in the Metroamp's 100w Plexi Kit's assembly instructions PDF document.

[FourT6and2]

Looks good!

Only tip I'd give you is that you're using too much solder in general. For example, when you solder a wire around a turret, you still want to be able to make out the strands of wire and the turret. The solder shouldn't completely engulf and cover everything.

Here's what it should look like: https://www.youtube.com/watch?v=RZmTkwTcC6Q

[Prowler]

Thanks for the tip FourT6and2! Do you think I should use a solder vacuum to take away some of the solder so that the strands of wire would be seen around the turret?

[Strat78]

That's a very helpful vid for future work, but what you have looks fine. Heating up the resistors and caps again just to take off a little solder will cause more harm than good.

[Prowler]

That's a very helpful vid for future work, but what you have looks fine. Heating up the resistors and caps again just to take off a little solder will cause more harm than good.

Yes, I think so too that heating them up again would do more harm. Right now I am checking if all the resistors are okay. One resistor's value has changed from 10k to 15k. I think I am going to replace it with a new one. It is that resistor that connects to 1M, 470 ohm and 1M resistors.

https://public.by3301.livefilestore.com ... jpg?psid=1

[FourT6and2]

Nah, you're fine with those joints. Just be aware of how much solder you use in the future.

And once a resistor is wired into the circuit, it usually can't be measured as it is interacting with other components. So that 10K that now reads 15K, might still be 10K. Your meter just can't measure it alone.

[Prowler]

Nah, you're fine with those joints. Just be aware of how much solder you use in the future.

And once a resistor is wired into the circuit, it usually can't be measured as it is interacting with other components. So that 10K that now reads 15K, might still be 10K. Your meter just can't measure it alone.

That might explain the meter's reading. Thanks FourT6and2!

[Prowler]

Now the final resistor is in it's place:

http://1drv.ms/1oyJ1gE

Today I checked if all the resistors were okay. One 47k resistor measured 4.7k while in the circuit. I checked the colour code and took it off from the circuit and it was 47k when I measured it again.

I also took a pic of the extra components that came with the kit. Is there any use for those?

[danman]

I'm not sure if it's the same with your kit but I know that the old MetroAmp kits use to have extra components, such as caps and resistors, for different variations of the circuit over the years. Marshall made slight changes to component values in these amps as the years went by and its your choice to decide which you prefer.

[Prowler]

I'm not sure if it's the same with your kit but I know that the old MetroAmp kits use to have extra components, such as caps and resistors, for different variations of the circuit over the years. Marshall made slight changes to component values in these amps as the years went by and its your choice to decide which you prefer.

Yeah, that might be the case. I'm looking at the Metroamp's Super Lead build instructions and it looks like that the 0.68uF cap is used in parallel with 680ohm resistor. Any idea how it affects the sound? I think I am going to try it. Thanks for the quick response Danman!

[danman]

Are you referring to the .68 cap bypassing the 820r cathode resistor on v2a? That is standard for a Superlead circuit and it basically provides a mid boost.

[Prowler]

Are you referring to the .68 cap bypassing the 820r cathode resistor on v2a? That is standard for a Superlead circuit and it basically provides a mid boost.

Yup. That's the one. Thanks Danman!

[Prowler]

I think It is ready for voltage measurings and testing:

http://1drv.ms/1sLtgIr

Please tell me now if you see anything that is not right.

-Andy

[Prowler]

Someone from the Finnish amp building forum told me that I should build a Dim-Bulb Tester:

http://www.antiqueradio.org/dimbulb.htm

Should I first do the Dim-Bulb testing without any tubes installed and then do the voltage measurings that are presented on the Metroamp's building manual?

http://www.metroamp.com/downloads/100_W ... MP_KIT.pdf

[danman]

When I built my first one I used a light bulb limiter with a 60watt bulb. First step was to plug into the limiter and turn the amp on without any tubes installed. You can check your heater voltages and negative bias voltage at this stage and also the high voltage off the PT secondaries. Next step is to take the amp off of standby and check your b+ voltages at tube sockets. I believe my light bulb limiter flashed briefly at this stage because of the filter caps charging but it quickly dimmed back down after a moment or two. Keep in mind that your voltages may read a little higher right now because you don't have the tubes installed. If all voltages check out good, you can then unplug the limiter, install your tubes and turn the amp on normally and recheck all voltages.