MayDac, a TDA1541A-based D/A-converter.

This project is almost finished, but I’ll put up all info on the build and pictures as soon as possible.

Based on:

TDA1541A

SAA7220P/B

0,3ppm 11.2896Mhz TXCO

Passive I/V

ECC86 tube output.

This is how the DAC-PCB looks right now.

MayDac

It started like this (some of the pictures you have to click on to view the whole picture)

Then it got more and more populated

TCXO

TCXO and homemade socket

Enclosure, used to be a tube preamp

Copper wall that will separate the transformer from the rest of the DAC

Custom wound transformer from Toroidy.pl

Mounted the PCB in the enclosure and set the 7 voltage regulators

Toroid will be installed further from the PCB with the copperwall between them.

2012-03-10

Done some work on the enclosure.

Made crude angles to mount ECC86 horizontally.

Braided 4×0,6mm silverwire in teflontubing for internal analog wiring.

Done! Waiting for 75ohm digital cable for the digital signal.

Changed from RCA to BNC for digital signal

75ohm 4mm diameter coaxial cable for internal wiring of the digital signal.

In place and screwed to the PCB, but not yet soldered in the other end.

All internal wiring apart from the wires from the transformer is now in place.

This how I’ll make the secondaries longer and also prefent shafing against the copper wall.

Got the philips ECC86 that eventually will be the outputstage in this DAC via passive I/V

2012-03-16

Started on the ECC86 output today.

PS cap(4700uF), resistor, 2SK170 via 100R trimpot to ECC86 plates.

2,2uF output cap and 100Kohm resistor between out and ground.

The free legs of the caps is where I’ll connect the signal from pin3(source) of the 2SK170’s

Temporary mounted shielded tubesocket to get a view of the layout

2012-03-17

Re-worked the layout of the MayDac. Thanks for the advice Lovan and reVintage!!

New digital wiring in place.

2012-03-19

Did some work on the ECC86 output and drilled some ventilation for the top of the chassies.

2012-03-20

Got some soldering done on the tube output.

Cathode resistors in place and set to 68R to begin with.

47nF and 47R in parallell to be put between gnd and signal in to grid.

2012-03-21

Front and sides in Oak arrived today ๐Ÿ™‚

Made a gnd point for signalgnd among other things.

2012-03-25

Not much left to do on the tube output.
Soldered connectors for signal to grid, wires for heaters and wires to cathode resistors.

2012-03-27

Done some internal wiring using silver wire. Also made ground points for the 47nF/47R-filter that comes after the I/V-resistors.

2012-03-29

Tube output buffer is almost done. Good because I have two Philips NOS ECC86 waiting to be used(one is to change tubes when the first one has lived it’s life) ๐Ÿ™‚

Wires going off picture is for heater, they will be twisted and soldered to chassis connector.

PS for B+

Purple wires are to be soldered to ECC86 plates.

2012-03-30

Finished the digital interconnect for this DAC.

Put in all the IC’s (will run it with IC’s before I run it with the ECC86 Tube output buffer.

At first power-up….nothing. The 500mA Fuse I used wasn’t enough. Switched it to a 1A Fast blow fuse, and now it works fine.

To early to really comment on sound quality, but after just 20min listening I can say that I’m not dissapointed ๐Ÿ™‚

2012-04-02

Got I/V-resistors from Hificollective today.

Amtrans AMRG and Holco H2

Also recieved a 4-pin connector so I can connect both wallwarts in the PS for the ECC86 tube output to one connector.

2012-04-06

I recieved the matched PIO’s for the tube output yesterday.

Did some work on putting the ECC86 tube output in to the DAC box today. Will continue during the weekend.

2012-04-07

Got some more work done on the tube output.

2012-04-08

47R Amtrans AMRG I/V-resistors with 47R/47nF-filter soldered to them. Wire that’ll go to signalgnd is also soldered. Left to do on this part of the build is to solder wires from I/V-resistors to signal out from the TDA1541A, and to solder wires from I/V-resistors to ECC86 grids(with gridstoppers between).

2012-04-09

Got some more work done on the tube ooutput. Also I connected the separate PS for the tube output to one 4-pin connector. And finally a first idea on how to place the I/V-resistors and filter.

2012-04-10 ย The Tube output is playing!! And playing very well I might add ๐Ÿ™‚

I had to correct an error I’d made with the I/V-resistors

And now it plays music like no other DAC I’ve heard ๐Ÿ™‚

2012-04-23

Finally got the heatsinks for SAA7220P/B ๐Ÿ™‚

That’s all for today, stay tuned!

/Mayday

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