Has anyone here done his suggested upgrades for the Bewitch 8550 chinese tub amp

Lewy5

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I have an old one I want to repair and I have his schematic and suggestions but I remember that some disagreed with him? So should I leave it stock or try to upgrade it?

Lewy5

  • Jr. Member
  • Posts: 13
I meant Bewitch 6550. Lampizator had reviewed it and suggested mods but some didn't like them and others had different suggestions.

I had raised the amp on some old matching glass candle holders but some tube sockets continued to actually get so hot their solder joints actually melted.

Mine is actually out of service now needing new power tubes etc? but as I spend the time fix it I'd like to mod it too and hopefully reduce the obvious heat problem too. Any ideas?

FullRangeMan

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I meant Bewitch 6550. Lampizator had reviewed it and suggested mods but some didn't like them and others had different suggestions.

I had raised the amp on some old matching glass candle holders but some tube sockets continued to actually get so hot their solder joints actually melted.

Mine is actually out of service now needing new power tubes etc? but as I spend the time fix it I'd like to mod it too and hopefully reduce the obvious heat problem too. Any ideas?
The hottest tubes in an tube amp are the rectifiers.
Weld melting can be caused by:
= Low-mass sockets that lack the mass to dissipate heat.
= Thin wire.
= Stranded wire.
= Hot Bias.
= Lead-free solder.
https://www.militaryaerospace.com/home/article/16708161/lead-free-solder-a-train-wreck-in-the-making

In this particular amp the huge main PCB does not allow hot air inside the chassis to come out.