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eBay 6SN7 / 300B Amplifier PCB Kit
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Author:  Woodo [ 09 Jul 2018, 17:46 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Nice place. Hope you enjoy your stay. Another week to go for my winter break after the school holidays. Will try to get some work done on the amp.

Author:  Woodo [ 11 Aug 2018, 19:04 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

I bought a can of black spray paint and gave a few quick coats yesterday. Unfortunately a few runs, note to self: please practice in future on non-critical sheet of metal. After 12 hours overnight seems mostly dry but will leave for a few days before attaching things.

Also cleaned the pcb board with isopropyl alcohol after reading about recommended cleaning solvents. Hasn't worked well as it has left a smudgy mess. Must be something better- are there any suggestions from the community? I'll post a few picks soon.

Author:  mwhouston [ 11 Aug 2018, 20:05 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

I've looked at a few of these kits because I currently have an abundance of 6SN7s and simular and would like to make a preamp with them.

I see you can buy bare boards which would be the way to go for me. Then pick your parts. But I can build a single stage preamp on two 50cent 5 tag tag strips so I think why pay for a PCB when a buck will do the same job.

Author:  Woodo [ 11 Aug 2018, 23:51 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Ideally I'd like to be able to do something like that too. Pcb projects are probably a little easier for a noob like me to get started. And I now recognise some of the disadvantages of pcb amps. If this project turns out I would like to have a go at the 6sn7 preamp you and Matt from memory collaborated on. I may need it if it turns out I extra gain is needed for this pcb amp as reported elsewhere.

Author:  Woodo [ 12 Aug 2018, 00:28 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Painting stage

Author:  mwhouston [ 12 Aug 2018, 00:32 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Much better than a bare chassis.

Author:  Woodo [ 12 Aug 2018, 05:42 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

yes i think so. i was going for a match with my b & w 2 way speakers which have mirror like black gloss finish.

Author:  Woodo [ 15 Aug 2018, 05:45 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Re-painted the chassis after sanding the pain runs. Not completely how I would like it but hopefully by next chassis I will have got the hang of it.

The pcb cleaned up well with isopropyl alcohol using an earbud/cuetip?. My wife's cotton makeup wipes work well on larger areas but leave a little cotton lint behind.

Author:  Woodo [ 15 Aug 2018, 06:32 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Please refer to updated schematic - comments welcome. Probably a bit rough.

Author:  Woodo [ 15 Aug 2018, 06:39 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Regarding the schematic, i have shown a potentiometer but there isn't provision for one in the pcb. I am making provision to fit one in case I don't need a pre-amp. Are there any views on whether it would work in this circuit with the 100k resistor or should this be removed or reduced? Also any comments on the operating points of this amp would be welcome.

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