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A few pcb's more...

Posted 7th December 2009 at 09:40 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)
Updated 7th December 2009 at 09:58 PM by Bas Horneman

With a dayjob and other "stuff" in my life. I don't always feel like conquering the cold and messy shed to go do some drilling. But I usually have other projects running parallel that I can do something on. Pictured here is the Pass B1 and the lightspeed pcb's. Stuffed...primarily because..... that way I won't loose parts in my messy hobby room.
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The Kendeill caps were too big for the B1 board. So I soldered the neg terminal to the neg hole in the pcb and wired the plus to the positive rail.

The wires of the 10uF cap I bent to go beneath the pcb and almost touch. I did this on purpose because I have some 0,22uF smd caps that will act as bypass for the Audyn polyprops. They will go between them wires there.
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Some more parts arrived for the BH

Posted 26th November 2009 at 10:10 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)
Updated 27th November 2009 at 09:40 AM by Bas Horneman

specifically I wanted to show the deflex washers that I'm planning on using.

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The deflex washers will probably look ugly. But I'm planning on putting them on top of the aluminium top plate. And having a bolt with separate brass washer "hang" on them. This bolt will then pass through a larger hole in the alu chassis plate to the wooden sub chassis that houses the tubes.

Also got the 470uF/100V caps for the bias blocks.
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Delivery

Posted 20th November 2009 at 07:48 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

Look what the mailman/woman dropped at my casa.

A matched quartet of GM70's (Almost ashamed at how little I paid for them) GM70's are for a SE GM70 amp with MQ parafeed iron.

And the 500R trimpots and 0,22uF caps for the Baby Huey.

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Ordered 500R pots for the driver stage.

Posted 18th November 2009 at 09:27 AM by Bas Horneman (Bas Horneman's diyAudio.com blog)

And while I was at it I saw some 0,22uF Epcos MKV from the same seller. The Epcos will do duty as coupling cap, as I've seen good reports (anecdotal) on them.

I asked Ian (gingertube) what the 470R resistors were for. Because I figured the CCS would take care of everything of the balance.

Here was his answer:
Quote:
The 1K pot is to set balance in the diff amp. The resistance in the triode cathode degenerates the tube gm (Ia/Vgk). Sweeping the pot wiper from side to side varies the amount of degeneration on each of the 2 triodes until they match. This is the minimum distortion condition for the diff amp. As we don't want to throw away gm un-necessarily we don't want those resistance values too high - just high enough to be able to adjust for matching behavior.
For a random sampling of 12AX7 and ECC803S that I had, 1K was too much, 100R was'nt quite enough so I dropped the 470R on each side of the 1K pot which effectively makes that pot about
...
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