NEED HELP! 50w kit

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

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NoellEagan
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Re: NEED HELP! 50w kit

Post by NoellEagan » Fri Oct 27, 2017 1:04 pm

Hi..i am a new user here. As per my knowledge If your meter is auto-ranging, it should find the correct scale on it's own as long as you are set to DC voltage. Two things that could also cause a problem are weak batteries in your meter and the possibility that you used a 10 ohm resistor on each socket and not a 1 ohm. The 10 ohm would still allow you to check your bias but your actual reading would be off by a factor of ten.

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Last edited by NoellEagan on Fri Nov 24, 2017 4:48 pm, edited 1 time in total.

Brad H
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Re: NEED HELP! 50w kit

Post by Brad H » Sat Oct 28, 2017 10:49 am

Thanks for the post, but I definitely said 1ohm in the first post. As I stated already, the bias range resistor Just wasn’t the correct value. The kit came with a 27k, but I needed a 33 or 47k to get the bias voltage where it needed to be. No big deal, but I worried a little that maybe that was just too easy, and the problem was bigger. Thankfully there are guys like us that subscribe to this message board and assist folks, or I probably would’ve pulled the rest of my hair out. :D

Anyway, thanks for your reply, nice to see folks are always willing to help out...you never know when a problem will hit you, and after all of that work, sometimes it’s tough to see easy fixes right in front of you!

:toast:

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neikeel
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Re: NEED HELP! 50w kit

Post by neikeel » Sun Oct 29, 2017 6:09 am

If you are swapping lots of tubes a different range pot is useful 0-100k for example.

Regarding the vol 1 bypass cap if you look at the interaction with the pot values a 500pF is very spiky. I tend to use a 100pF for amps that get used at lower volumes. The original lead amps all run 5,000pF, any thing else is a mod, and the plexis are usually very smooth in comparison with the metal panel amps.
What cap are you running on V2a and what NFB resistor/tap combo?
What sort of tones are you after?
Neil

Brad H
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Re: NEED HELP! 50w kit

Post by Brad H » Sun Oct 29, 2017 7:31 am

Honestly I removed the bright cap completely, sounded much better! V2A cathode resistor/ cap combo are an 820/.68uf. NFB is a 100, attached to the output jack positive terminal. Was looking to heat up the power tubes without teeth grinding highs, so removing the bright cap got me there. Could’ve used a 100, but the lowest I had was a 250, and I figured that wouldn’t be enough. Turned out great!

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