I need some help with mods I performed on a 6505 112?

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JamesLucas
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Posts: 1
Joined: Sat Oct 31, 2020 3:30 am

I need some help with mods I performed on a 6505 112?

Post by JamesLucas » Sat Oct 31, 2020 3:43 am

Hi All

I bought a 6505 112 which was rather cheap.

Person that I bought it off said it had a blown tube.

Amp was bought to be intended as a mod base, as I already have a few 6505s.

Few issues with this amp tho -

Cracked solder joints on few tube sockets (fixed)
Few blown traces on PCB (installed jumper wires)
Burnt resistor ( replaced )

The amp came back to life with volume!

I performed these mods -
1) Replace the 470pF capacitor at C5 with a .0022μF capacitor and a 470KΩ resistor in series
2) Replace the 1nF capacitor at C26 with a .022μF capacitor.

The amp has more lowend - but unresonable amount of gain. I'm talking 2 on lead channel is fuzzy and on 5 it squeels.

on the rhythm channel - there is also too much gain - I know these guys can't do much of a clean tone - but I can't get anything clean.

Can someone point me in the right direction here of where I could be looking at?

Thank you so much!

rogue777
Member
Posts: 301
Joined: Mon Sep 14, 2009 7:07 pm

Re: I need some help with mods I performed on a 6505 112?

Post by rogue777 » Tue Nov 03, 2020 10:10 am

Great, sounds like your part changes had an effect, although the original parts maybe a better choice. If you use a scope and a sig gen, you could visually see the voltage gains and waveform distortion as you try different parts at different freqs.

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