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100 Jfets on their way :)

Posted 9th October 2009 at 11:15 AM by wintermute
Updated 11th December 2009 at 12:17 PM by wintermute

Its been really cold the last two days.. I was thinking whilst walking to the train this morning that I should have worn my winter coat! (Cold by Sydney standards anyway, The Northern Hemisphere people would laugh at my notion of cold)

The weather has unfortunately had a damping effect on the progress of my speakers too. First problem is that my workspace is the balcony, and it has been very windy and stormy, so I haven't risked doing any more veneering.... Second thing that worried me was that with the wet weather I might have troubles with splitting.

So Last weekend I placed an order for 100 2SK170BL's from Spencer. He sent them on Monday so hopefully will have them in about a week. The plan is to build a B1 buffer (ultimately I suspect there will be more than one), to finally do away with the abomination that passes for a preamp in my Integrated Series 200 amp.

The B1 will I think be the easy bit... I will probably build it on perfboard or vero boad. Still debating whether to do the Salas version, Though if I do then I have to do a power supply, thinking at the moment I might just wimp out and make the stock version. The hard part will be the rest.. volume control and input selection... I've had so many problems with volume control in the past, I'm not sure which way to jump... I'd love to have remote control too, but I think that is something for the future... In the end I'll probably just get a six position switch and a 20K pot and stick it all in a box, and then talk about making it better for the next 20 years

Down the track though I do need to do an active crossover.. looks like it will be a while before the B3 comes out, so I will probably do something nasty like stick a B1 on either side of an opamp for each of the low and high pass sections.... either that or a single B1 followed by a couple of passive filters and then another couple of B1's for the output.. time will tell I guess!


Note to self. 200Hz crossover 11.8K Welwyn RC55Y with 68nf caps looks good.
Posted in misc
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Total Comments 2


  1. Old Comment
    peranders's Avatar
    Have you noticed that I have ordered nice red goldplated B1 pcb's? They could be yours.
    Posted 15th October 2009 at 12:29 PM by peranders peranders is offline
  2. Old Comment
    wintermute's Avatar
    I did PA It is a sad tale which will hopefully have a happy ending

    As I am potentially going to be making a few of these, I was intending to build on verro board... If I'm not happy with it, then I might consider purchasing some PCB's but at the moment since this is such a simple circuit (and NP specifically says it can be built as such) I'll give it a go... My first amp was actually on perfboard (the stuff with no copper). I've even contemplated doing it P2P

    Posted 18th October 2009 at 10:45 AM by wintermute wintermute is offline

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