Van Waarde inspired OTL headphone amp

[Rodney_gold]

I would imagine it would be a lot cheaper in mild steel , aluminium is a bear to laser cut and weld. I have lasers at my factory - unfortunately not high enough power and of the wavelength to cut steel or ally - we do plastics like acrylics, perspex , corian , formicas  and other organic stuff like wood.
I would be interested in how the headamp sounds - I use Hd800's and have a set of AKG 702's on its way.

[Mars]

After the shock of the initial quote wore off, I discussed the manufacturing process with the sales representative at Fabrinox.

It turns out the material costs are negligible. It is the stripping and finishing (sanding the welds) that adds to the price. Since their welds are pretty neat, we have decided to do a trial run on weld only; no finishing.

The quote came to


MAR019-00000048-1 COVER PLATE 1200H4 02.0mm No
MAR019/00000048-2 HEAD AMP ENCLOSURE 1200H4 02.0mm No
Unit Price Total Price
(Excl. VAT) (Excl. VAT)
1 R 36.81 36.81
1 R 478.40 478.40
Comments:
WELDING INSIDE AND OUTSIDE
NO STRIP FINISH WELDING
COVER PLATE AND BOX SEPERATE
Subtotal
VAT
Total Net Price
Please Note:
R 515.21
R 72.13
R 587.34

This looks a bit better, and I've decided to go with this option, and will evaluate the outcome.

[GearSlave]

Just as a suggestion, try and have the chassis made without welds if possible. Just stick to bends for strength if you must. This is the way I've been doing it and the way it's done commercially; the less human work to do the cheaper it'll be. That way you can stick to aluminium without worrying about welding it.

[Mars]

I think I might go with your idea in the future.

BTW the aluminium box is ready at Fabrinox. I'll pick it up next week and post the outcome.

[Mars]

Some pics of the chassis

[kamikazi]

Hows thing going with the build with your headphone amp?

I'm currently looking into getting a tube-based headphone amplifier for my new cans.

[Mars]

I just got the chassis back from the painter:






I am going to mount all the hardware and post a pic.

[kamikazi]

Thanks for the response! The chassis looks really good, can't wait to see how it will look with everything mounted.

[Rendlan]

Hi!

Any chance of a schematic for the final design?

Cheers!

R

[Rendlan]

Also, would this be SRPP OTL?

[Mars]

I am following the Wheatfield HA2 design. See the schematic in the User Manual here

http://www.pmillett.com/Wheatfield/manual.pdf

[Mars]

Hi All

Some update on the project.

• the transformers are completed
• and mounted
• tube sockets are mounted
• electrolytics are mounted
• busy finalising the layout of the oil caps

I'll post a redrawn schematic soon.

[iondb]

This is looking really good.

[Mars]

I drew up a schematic for the Mars HA2



https://lh5.googleusercontent.com/-N66ZsYFjAwU/TkKxUG_m9PI/AAAAAAAABVo/v_v9GzN05z8/s640/Mars-HA2-large.png