My new DAC

[Jameson]

Party at Geary's!

 

[Deke609]

Deke,
I am a Neophyte to Dacs also, but many years ago I had a Theta Dac all solid state, it was considered a great Dac at the time. Sadly that was stolen from me with many other items. This Dac has an analog line out using 6922/ 6dj8 or equiv. tubes. The B+ supply is tube also using a 6x5 tube and a 6bm8 regulator. It sounds quite nice to me. I may try a SS rectifier at some point but I must say I am digging the arrangement right now.

I listen to the descendant of the Theta, Schiit's Yggdrasil, both of which were designed by Mike Moffat.

Thanks for the info about how the tubes are used in the DAC. So I'm guessing that the actual DA conversion is done by one or more chips and the tubes only come into play (other than via the power supply) after that -- which makes sense since a tube, if it is acting as a signal amplifier, needs an analog input at the grid.

Enjoy your new DAC!

cheers, Derek

[edited to correct a bazillion typos]

 

[Thermioniclife]

Will do Derek, have been listening with my C2A, will try with my Mainline later today.

 

[Doc B]

Yes "tube DACs" simply have a tube gain stage after the DAC chip, which is a SS device. Many years ago I talked to John Swenson about building an all tube DAC, i.e. the digital to audio conversion done with tubes rather than a SS chip. The idea kinda crashed when we guessed we would need around 50-100A just for the heater supply for all the tubes.

 

[galyons]

Doc, I can imagine!! (WARNING! TMI to follow!!)  I have had several opportunities to visit Iowa State University in Ames. They have on display the Cyclone computer they built in 1959.  The Cyclone has somewhere around 2,700  tubes. Over 1500 were 5844's used as switches.  The Cyclone required a dedicated cooling system and  was 10 feet tall, 12 feet long, 3 feet wide. The Cyclone used 19 Kw of electric power and weighed about 5,000 pounds. It had less computing power than a 1970's handheld programable calculator.  The Cyclone was powered up about the same time IBM released a solid state computer. And the rest is history!!

DAC chips are typically pretty simple devices, especially R2R chips. I think the receiver chips are more complicated. 

Cheers,
Geary

 

[Deke609]

Yes "tube DACs" simply have a tube gain stage after the DAC chip, which is a SS device. ...

Thanks Doc. That's what I wanted to know.

cheers, derek

 

[Karl5150]

Geary, the computer shares the name of the school's mascot. My daughter is an alumni and resident...I'll see if I can enlist her to get a photo or two.
Sorry about the hijack Lee, enjoy your DAC, it looks like an amazing bit of kit.
Karl

 

[2wo]

My grandfather was a Western Electric man, he helped wire up Einic at U Penn during WWll...John