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diy audio and stuff

my diy audio and life

Filed under: minimax dac

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!

Eastern Electric Minimax Dac

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I started to investigate USB dacs after wanting to have a singular place to playback my cds. The idea is to convert my macbook for this service, playback will be via iTunes, controlled by iPhone's Remote app. Well... I can continue to be a couch potato. Haha.

Then I looked for a suitable USB solution that would be able to offer a good link to my system. Initially wanted to get the Teralink with the power supply from Vintage Audio Lab (24/96 USB interface) since they cost only USD135 for the whole package. This would allow me to DIY flavour of the month DACs if I so choose to. I then read about the Eastern Electric MiniMax Dac that uses the ESS Technologies 32 bit Sabre 9018 chip and all the glowing reviews about this giant killer. Best of all, there is a local dealer in Singapore, and they happened to have a one-off sale for the current batch of shipment. The Sabre series of dacs are also very well received in the DIY audio communities, and the Twisted Pear stuff are mostly on waiting queues.

I immediately SMSed the dealer to tell him that I'd drop by. After a quick 30 mins of listening, I got the DAC. Not that it was easy to tell from an audition that it was good, but because the dac sold itself due to the rave reviews.

With the dac back at home, i immediately plugged it in. Wanted to run it in enough so that I can listen to it over the weekend. The next few nights I slept late. Not due to the great music, but rather, the lack of. I tried all means to run in USB with my MacBook, but it just does not recognize the device in Audio MIDI Setup (AMS). I was not able to select the device as an output device. I only had internal speakers as output device in AMS. Thus I was not able to route the music to the DAC. It will always be played by the internal speakers. The ASIO drivers worked, but the trial ones for Mac had a 30 sec beep tone. The driver would cost 44 euros if I were to purchase it. I've never had to pay for a software driver before! It should come with the product... but Mac's coreaudio does not seem to work for my case.

After texting the dealer, he said some of the local buyers use Mac and it works for them. He also reiterated that a driver is not required. Maybe it is the MacBook... I've no idea. Anyways, I've more or less shelved the plans for a hard disk audio setup on Mac. I did not know Mac has such PITA issues with USB and coreaudio. I'll just enjoy the dac with my cds being played by my cdpro2 transport.

Some of my listening impressions of the dac can be found here. I think there are room for mods to be done on the dac. Not sure if these mods would necessarily bring about improvements. For one, I just changed U1 and U2 from NE5332 to LM4562 (similar to LME49720, i have 3 lying around). This is supposed to be for the I/V stage and this change works for both opamp and tube output mode. Not sure if it was due to this change, but while i was listening to around thr 4-5th track after the LM4562 opamp change, the audio disappeared for a second or 2. Thereafter, I did not listen as it was getting late. After switching off the system, I touched the LM4562 to feel the temperature. It was warmish. Maybe I should check if it is around the same with the NE5552 in place. That's for another day I guess.