DIY Audio Projects Forum
http://diyaudioprojects.com/Forum/

6418 Tube / Opamp Headphone Amp (Oatley Electronics K272A)
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=1528
Page 38 of 43

Author:  richleicester [ 21 Feb 2013, 15:47 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

Hi,

I'm new here and found the place because I have just been building an Oatley K272A and have a couple of questions about the final stage of putting it in a box.

I've attached an image of where it is at currently.
Attachment:
photo.JPG

1. I really want to have the two pots that are in the lid controlling the volume, but have already soldered in the two little board mounted pots. Can I use the extra three solder points to add the extra pots? I gave this a go, using 1M log pots, which are in the lid, but they appeared to actually boost the volume even though I thought they would just both act as passive volumes that would just 'cut' the signal? Has anybody got any good tips on this before I go any further?

2. What does the 5V solder point do, out of interest?

Cheers
Rich

Author:  mwhouston [ 21 Feb 2013, 18:12 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

You will have to remove the board mounted trimmers.

Author:  richleicester [ 23 Feb 2013, 04:29 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

Cool. Can anybody explain why the pots would behave in this way?

Author:  mwhouston [ 23 Feb 2013, 06:21 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

It is just the way the two pots are working together. It will be much better when you remove the other trimmers. Please provide an image of the wooden case with lid closed.

Author:  nicinico [ 14 May 2013, 00:00 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

New here and just want to share my K272A kit using DIY PCB.

Image
Image

Modified the circuit to use a single 9v and using the same voltage on PT2308 pin 8.
Also a lever switch is placed on the headphone jack to turn on the power.

Author:  atanguay [ 14 May 2013, 08:38 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

How cool. Great job.

Author:  Robbie7 [ 14 May 2013, 08:48 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

Very nice :)

Author:  mwhouston [ 14 May 2013, 08:52 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

I thought I post a reply but it seems to have vanished. What a great build and a great idea. If there were red LEDs deep down in the box it would look likes glowing tubes. I'm inspired.

I have a K272C prototype and two K272C kits to assembled. The K272C is really excellent sounding. My two builds will be very plane though compared to this.

Author:  nicinico [ 14 May 2013, 18:51 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

Thanks for the appreciation.

mwhouston wrote:
If there were red LEDs deep down in the box it would look like glowing tubes.


There's a Blue LED between the pins of the two tubes and a Red LED for indicator.
I'm planning to change the Blue LED to Amber for the glow effect. :idea:

Image

Weak battery.
Image

Author:  mwhouston [ 14 May 2013, 20:33 ]
Post subject:  Re: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272

Nicinico: that looks great. I agree amber may just be a little better. You are right one led will do. I must try the whole idea.

Page 38 of 43 All times are UTC - 6 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/