diyAudio - Entries for November 2009

Other channel...

Posted 30th November 2009 at 10:53 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)
Updated 30th November 2009 at 10:59 PM by Bas Horneman

starting to look like it...

Actually wanted to continue on the Baby Huey but it was late. And did not want to keep everyone awake while drilling.

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Building, Gainclones

Views 480 Comments 0 Bas Horneman is offline

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.

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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Bas Horneman

diyAudio Moderator Emeritus

Posted in Building, Buying

Views 438 Comments 0 Bas Horneman is offline

It'll take a while to build the gainclone ;). And I'm going

Posted 25th November 2009 at 09:02 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)
Updated 26th November 2009 at 03:13 PM by Bas Horneman

to need an attenuator as well. Because the Gainclone will be set up as a power amplifier only. I put together a makeshift attenuator of parts I have. And of parts I want to use in a full blown tube preamp.

That way I can ...dare I say it...burn-in the transformer. Even if burn-in does not exist...it won't hurt.

Also some mock up shots of the GC. "Enclosure" is some Ikea DVD storage system that was on a sale. Something like 2 euro's or so.

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Building

Views 499 Comments 0 Bas Horneman is offline

Another baby step with the LM3886...

Posted 24th November 2009 at 08:14 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

...

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Gainclones

Views 2033 Comments 2 Bas Horneman is offline

It will take a while before the Baby Huey is done...

Posted 23rd November 2009 at 10:52 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)
Updated 24th November 2009 at 05:01 PM by Bas Horneman

therefore in between I'll be posting progress on my LM3886 "gainclone"

I soldered the boards a long looong time ago. So no pictures. And I don't think anyone would want to see these boards soldered part by part. pcb's are boring in that way.

The build will be quick and dirty. But still something I could "live" with. Hopefully.

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Gainclones

Views 723 Comments 3 Bas Horneman is offline

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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Bas Horneman

diyAudio Moderator Emeritus

Posted in Buying

Views 337 Comments 0 Bas Horneman is offline

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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Bas Horneman

diyAudio Moderator Emeritus

Posted in Buying

Views 331 Comments 0 Bas Horneman is offline

Slowly but surely making progress

Posted 16th November 2009 at 10:36 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

I have used a diy fluid for drilling for the first time. Used bicycle chain oil...water and detergent. Quite happy with it. Drilled the largest hole yet. And it looked almost professional.

Also a photo of the oak enclosure after it was treated with boiled linseed oil. The oil makes the oak enclosure look a lot better, it really brings out the grain. As usual I don't have "before" pictures to show the difference. (the pictures below had a partial coat already)

I'm not sure what to seal the wood with. Suggestions are welcome. Right now I'm thinking about shellac.

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Building

Views 286 Comments 0 Bas Horneman is offline

Output tubes's CCS's (bias blocks) completed.

Posted 15th November 2009 at 12:14 AM by Bas Horneman (Bas Horneman's diyAudio.com blog)

sans bypass cap.

Measure 380mV accross a 10R resistors. Therefore the CCS is set to 38mA.

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Bas Horneman

diyAudio Moderator Emeritus

Posted in Building

Views 322 Comments 0 Bas Horneman is offline

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