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PostPosted: 22 Apr 2013, 18:15 
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atanguay wrote:
What's the plan for the end? How about laser cut black acrylic? 8-)

The end cap of the tin just clicks on. Idea is take off the cap, plug in, play. When finished, unplug and re-cap.

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PostPosted: 22 Apr 2013, 23:58 
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Intermezzo has always had a slight buzz and hum through the Fostex (what do you expect with speakers of 96db efficiency - I can hear fleas communicating from 1 mile away). Today I earthed the filament tranni and the step-down-up trannies. This is probably a good idea from a safety point of view but had no effect on the resident buzz and hum. I must say I played the amp for a few hows to some golden ears of the audio club and none remarked on the "noise". Yes it is extremely low but I thought I would have a go at reducing it.

Next I will try earthing the metal case and OPT's frames. From there the inter-stage frames. Both the input and outputs float. I could try earthing them as in the original cct.

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PostPosted: 01 May 2013, 22:53 
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The K272C is avaialble from the Oatley site. Kit cost is $40. When you consider you are getting an OPA2134 chip in this kit then I think the price is justified.http://secure.oatleyelectronics.com//product_info.php?products_id=1027

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PostPosted: 14 May 2013, 21:21 
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I will document the assembly of two K272C kits from scratch. Must say these brd. are first class. Extremely easy to solder and work with. The parts are only pedestrian but for $40 for the kit is seems reasonable. Take a look at the kits and assembled brds.
Attachment:
Kits.jpg
Attachment:
Brds.jpg


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PostPosted: 20 May 2013, 01:12 
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One is finally finished and mounted in an ABS plastic enclosure. I have used these enclosures for lots of projects. They are good size and reasonably cheap. Once again I Al lined the enclosure. The B+ and filament leds are brought to the front off the cct. brd. I chose a red led for filament and yellow for B+. This is a great upgrade Oatley has made to the "C". As the leds dim then finally go out you are aware of the health of each battery even before it goes flat. And the sound, weighty and solid. I used my "safe on" technique here where you need both plugs in and the switch on before power flows. Switched phone sockets make that easy.
Attachment:
Fin.jpg
Attachment:
FinII.jpg


Push button on\off switch is on the rear.


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PostPosted: 20 May 2013, 21:15 
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Nice little headamp build. Are you liking the amp better with the higher B+.

Cheers

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PostPosted: 21 May 2013, 04:32 
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Gio wrote:
Nice little headamp build. Are you liking the amp better with the higher B+.

Quick answer at this point Gio, Yes! More to follow.

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PostPosted: 22 May 2013, 19:18 
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Both K272Cs complete with name plates just called the "K272C". I'm very pleased with the build and sound. They do sound extremely good.
Attachment:
FinV.jpg
Attachment:
FinIII.jpg
Attachment:
FinIV.jpg


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PostPosted: 09 Oct 2013, 18:53 
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Hello,

so I've just ordered a kit from Oatley and while I wait for it, I figured I'd ask a question or two.. if any of you guys are still checking this thread, I'd be really grateful for a bit of guidance :-)

Having read through the whole K272(A) thread I'd like to ask about parts upgrades. Should I stick with stock parts? Should I just swap all the resistors for their 1% metalized equivalents? How about the caps? How much of an improvement would such upgrades make?

Other thing: as I would mostly be using the preamp at home, I was thinking about building a PSU for it. Is there anything in particular I should be watching out for? Of course I'll need large filter caps and a separate 3V rail for the filament..

Thanks a lot in advance!


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PostPosted: 09 Oct 2013, 19:37 
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jahudka wrote:
Hello,

so I've just ordered a kit from Oatley and while I wait for it, I figured I'd ask a question or two.. if any of you guys are still checking this thread, I'd be really grateful for a bit of guidance :-)

Having read through the whole K272(A) thread I'd like to ask about parts upgrades. Should I stick with stock parts? Should I just swap all the resistors for their 1% metalized equivalents? How about the caps? How much of an improvement would such upgrades make?

Other thing: as I would mostly be using the preamp at home, I was thinking about building a PSU for it. Is there anything in particular I should be watching out for? Of course I'll need large filter caps and a separate 3V rail for the filament..

Thanks a lot in advance!

Component upgrade is simple. Just replace all carbon Rs with metal film. There are four caps in the audio path replace these with better polies and the output caps I replaced with low ESR equivalents. No comment on the replace PS.

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