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eBay 6SN7 / 300B Amplifier PCB Kit
http://www.diyaudioprojects.com/Forum/viewtopic.php?f=9&t=6153
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Author:  mwhouston [ 24 Jun 2018, 06:57 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Pete D wrote:
Hi Woodo, yes this is a problem - getting a pleasing layout whilst satisfying the electronics!

Firstly I wanted my build to be symetrical for aesthetic reasons, secondly it had perform well as well as possible with short lead lengths etc etc. Very simplistic I know, but that led me to only one possible layout.

So my mains tx and choke were central, the choke being 20mm or so from the glass of the rectifier. The output transfomers were centrally right behind the 300B's (note the mains tx is rotated 90 deg). The resultant amp has no discernable noise/hum etc.

When I did my trial layouts I found that no commercially available chassis would quite give me the layout I wanted, so had to bite the bullet and make my own.

Pete

I remove the stickers from the Hammond trannies and stick them on the base plate. That way I know what trannies have been used where. The stickers are ugly.

Author:  Woodo [ 26 Jun 2018, 04:03 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Thanks Mark. Luckily the Edcor stickers are provided separately. I hope to find a place to stick them that I don't need to use. The box I got is a touch small.

Author:  Woodo [ 26 Jun 2018, 17:22 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

I was a bit depressed to hear a fellow building what looks like the same pcb kit found the completed amp had insufficient volume. A few solutions were advised with the chosen one substituting the 6sn7s for different valves with more gain. If of interest see http://www.diyaudio.com/forums/tubes-va ... oject.html
Hopefully it's ok to mention another forum. My apologies if not.

Author:  mwhouston [ 26 Jun 2018, 18:14 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Woodo wrote:
I was a bit depressed to hear a fellow building what looks like the same pcb kit found the completed amp had insufficient volume. A few solutions were advised with the chosen one substituting the 6sn7s for different valves with more gain. If of interest see http://www.diyaudio.com/forums/tubes-va ... oject.html
Hopefully it's ok to mention another forum. My apologies if not.


Generally you can substitute a 6SN7 for 6SL7 which has greater gain.

Author:  Woodo [ 30 Jun 2018, 19:53 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Some of those small resistors are close together on the pcb! Doesn’t help i’m all thumbs when it comes to soldering. The 750 ohm resistors on the 6SN7s don’t fit in the holes so i’ll need to source some others, they seem to be substantial resistors. photo to come

Author:  Woodo [ 08 Jul 2018, 04:29 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Visit to Jaycar found the missing 750R for the cathode resistor for the 6sn7 (is that the right way to describe this resistor). I've noticed that a number of other circuits for the 6sn7/300b use a 470R at that spot and I wondered what effect that would have on the performance of the amp. A good grasp of ohm's law and load lines would be handy. Some pics works in progress. Neatness needs improvement and can't seem to get all the sockets in the perfect alignment but I'll keep forging on.

Author:  mwhouston [ 08 Jul 2018, 05:02 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Woodo where in Oz are you from? I'm Southern Vic.

Author:  Woodo [ 08 Jul 2018, 21:51 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

I'm in Brisbane Matt which today is a bit chilly considering the warm winter we had been having. I realise we don't know what cold is up here.

Author:  Woodo [ 08 Jul 2018, 21:58 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

Sorry, Mark I meant. I've been reading too many projects by you and Matt and got confused.

Author:  mwhouston [ 09 Jul 2018, 04:12 ]
Post subject:  Re: eBay 6SN7 / 300B Amplifier PCB Kit

I'm on the Sunshine Coast, Moffat beach at the mo.

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