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diy audio and stuff

my diy audio and life

Filed under: rgn 1064

I/V for Sabre32

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I ordered the Twisted Pear Buffalo32 version 2 DAC some time ago. It's quite a different order process from other stuff in that I had to queue to register my interest and pay for it first. It's like queuing up for new condominium launches in Singapore...

Anyways, there is the need to do up an I/V stage for this DAC. There's so many choices out there... and coincidentally, John Broskie had a newish Broskie Cathode Follower design on his site. I then built the BCF for 6H30 tubes. The tubes will be powered by a Salas High Voltage Shunt regulator, which would be recitified by my Telefunken RGN1064 mesh plate globe tube. All great stuff in their own right. :)

I was checking TubeCad today and Broskie had an update to the BCF in the form of The Unbalancer. An input differential voltage gain stage is added to convert the lowish voltage swing into something more usable for an amplifier. Well... this made sense. I was just hoping that the BCF alone will be able to do the job... Seems I will need to put something here. I've got 5 stars GE 6072, but the gain (44, i think. The Unbalancer circuit used a 12AX7 - gain of 100) may not be enough. I'm thinking of using my red base 6SL7 (gain of 70), which would be a better candidate. Or maybe I should buy some 12AX7...

Just over the weekend, we had a Sabre32 mini shootout with 3 different implementation of this chip. My EE MiniMax DAC, Nick's Amplidac, William's UTS. We played some very nice cds. I especially liked the Sara K & Chris Jones - Are we there yet? and a Koji Tamaki cd.

You're gonna ask me which implementation won... Well... it's down to personal preference. The Sabre32 signatures of better resolution, imaging and soundstage are definitely there. For DIY guys, this is an avenue to custom build a Sabre32 DAC to their liking that matches their system.

Guess I can only pursue this after my reservist which starts tomorrow... In the meantime, enjoy your music!

RCA 834 Tubes

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Went to the post office to collect the 2 pairs of RCA 834 tubes. While collecting the B4 sockets for the Telefunken RGN1064 from Joh, he mentioned that the top pins would need to be "heat sinked" in order to dissipate the heat otherwise the glass would crack. One of his friends encountered this issue with a similar tube. I remembered coming across a site somewhere on the web where a DIY guy can help machine those top caps meant for the 833 tube. Need to do some searching...

Anyway... this will be a build that I'd attempt only after I managed the RCA 808, which has been in the pipeline for a long time. I need to finish up the 1626 first (some adjustments need to be done on the aluminum plate so that the top plate can be accommodated. need to get a few short standoffs as well), then build the Sabre32 DAC with Broskie Cathode Follower with a Salas High Voltage Shunt regulator, before the 808 project starts.

RGN 1064 tube rectifiers

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Managed to add a pair of RGN 1064 rectifiers to my stash before the prices go further northwards. The larger RGN 4004 are already at very high prices and limited availability at the moment.

I've got one Loewe and the other is a Telefunken. Both are mesh plates. Sound-wise, the bigger the mesh, the better it is supposed to sound. I don't have plans to use these yet, but perhaps in a future 45 amplifier project.