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Giaime 10th April 2006 07:43 PM

Giaime's Preamp Finished!!!
2 Attachment(s)
Hello everybody!

I'm so happy... I finally finished my line+phono preamp :D

Schematics: phono stage (I'm not yet sure if I will add a bypass cap on the cathode of the first stage)

Giaime 10th April 2006 07:44 PM

2 Attachment(s)
Line stage:

Giaime 10th April 2006 07:46 PM

2 Attachment(s)
High voltage power supply:

Giaime 10th April 2006 07:48 PM

Filament supply: no schematic, just a bridge rect, 100nF, 4700uF, 4R7 and 12AX7 filaments, wired in parallel with the series of the ECC88 heaters (to get 12.6V).

Sorry... no photos yet :xeye: I will do the best I can in finding some digital camera to make some shots... it has a black "C shaped" chassis with wooden sides.

Now it's playing :D

poobah 10th April 2006 07:53 PM

Good for you!!!!!!!!!!!!!!!!


Rocky 10th April 2006 08:13 PM

Now that's an unusual topology.. Never seen anything like it.

Tell us about that line stage...

Giaime 10th April 2006 08:20 PM

Hello Rocky,

I'm very grateful to all DIYaudio members that helped me along this journey ;)

That line stage has its roots in the requirements I had when designing it, it can provide all my goals in a very good way.

It had to be:
- some gain, max 5 not more
- high input impedance
- low output impedance (it has to drive power amps directly)
- low distortion, low coloration
- only one tube, and better if ECC88.

You'll see that with those requirements it cannot be much far than that :D, maybe a step up trafo and a CCS-loaded cathode follower would do, but I'm cheap I don't have money for trannies :xeye:

So I developed it thanks also to TubeCAD: that circuit is listed under "Plate Follower" circuits.

Thank you for the interest!

Rocky 10th April 2006 10:18 PM

Very nicely done. It's not easy designing quality equipment on a budget ;)

Giaime 15th April 2006 04:20 PM

Here it is :D :D :D

more on my site

Geek 15th April 2006 04:25 PM

Right on buddy! :)

Now we pop the cork on some Asti and celebrate :D

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