Phono Pre EAR 834 | SkunkieDesigns

Hey Skunkie,

I really appreciate the Channel and the site. I had done a few DIY electronics projects a few years ago but no undertaking like this. I had a great time and your advise, videos, and BOM were so helpful!

Here is a little summary of my build, as you will see I took a few liberties with the design, config, and choices.

I went with a Hammond CHASSIS STEEL BLACK 10"L X 17"W X 3" to have a shape more like a regular Hi-Fi component splitting PCB power section on the left and right sides of the box. I chose NOS US 12ax7 tubes which were a great choice. I laugh out loud when you mention not to go fo JJ which has also been my experience using them in Hi-Fi applications. I also jumped for the PCB speced transistor (found on eBay about $8.50) rather than the lower rated one from the kit. the other change i made was pulling a 6.3 volt parallel power line for the power light and installing a fender amp light rather than the blue LED as a power indicator.

I used Digikey for most of the hardware, but also noticed a lot of these components are sourceable at an okay price on tubedepot.com (who actually fulfilled the tube parts from the digikey). Tube Depot part and accessories "DIY Central" was awesome and good for a browse. Mundorf caps and high accuracy 47k resistors from soniccraft.com. I didn't find that paying extra for high accuracy on the matched resistors was necessary since the 1% accuracy resistors were often ~0.1% when buying 5 or so parts.

The build was a lot of fun and almost as enjoyable the final product. I had only one issue during the whole build was the placing the 100UF 10V cap on the top side of the board caused a short on the signal path trace below it. So, I can also advise, as you did and the makers of the bard did, it is best to place that component on the other side.

I have also included a bulkhead in my build after these pictures were taken, but the noise floor was already very low i wasn't able to notice a difference. one question i had was there a reason you didn't connect the power board to the chassis ground?

Thanks,

Dan from Chicago

5 Comments

daniel777

20h

Are you finding that your case gets rather hot due to no ventilation? from the transformer and from the tubes?

I cant help but feel that the life expectancy of the valves and transformer would be significantly reduced... I have a ready made one - split - but they both get hot ... I am thinking of raising the tubes via 3 holes to outside the case on top, while inverting the capacitors...and cutting a square hole above the transformer and putting aluminum mesh grounded - so that the hot air rises out of there...and greater convection cooling occurs... The only issue would be, would this lessen the faraday earth effect of the case and induce more hum...?

Edited