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Messages - Synkopy

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Amplifier Discussion / Re: Marshall 3005/Lead 12 Power Trans Question
« on: January 04, 2020, 10:10:36 PM »
EDIT: in a nutshell:
a) they originally use 8 ohms speakers, (or 2 x 16 ohms)  so if you have original speakers or replaced them with other brand 8 ohms ones, fine, you have changed nothing except improve sound quality.
b) the amp design and parts used stands way more, I have personally loaded them with 4 ohms and got around 20V with no ill effects.
The transformers I tested were fine, warm but not *hot*  .
Same with heatsinks.
c) in theory you can turn that amp into a 50W or more one, *if* you provide better supply (beefier transformer and higher voltage electrolytics) and mount transistors in a "real" extruded finned heat sink, and adjust dropping resistors values to still feed +/- 15V to preamp.

I haven't modded original ones but straight built new ones, with the beefed up supply and heatsinking I mentioned, for killer 50/60W combos.

Sorry to revive an ancient thread. But I came into possession of one of these amp heads recently and wanted to thank you so much for this. As I’ve managed to do just what you’ve described. Upgraded electrolytics, bigger transformer, upgraded heat sinks, and rectifier, and adjusted drop resistors. Also made a small capacitor change to tame the fizzy top end and added an op amp socket for good measure. This little dude can easily keep up with my 60W blackstar now!

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