Prototype DAC PCBs (TDA1541A, TDA1545, AD1865N, 5687)

[dsavitsk]

I have been working on some NOS DAC stuff, and I have some extra circuit boards to sell off as board houses tend to not make just one. There is a TDA1541A based board, a TDA1545 based board, an AD1865 based board, and a 5687 based tube gain stage board.

All three DACs use a transformer input; the ad1865 also uses an active buffer.

The TDA1541A and AD1865 DAC's have spots to use a passive I/V as well as a Bessel or Butterworth filter, or you can bypass one or both parts to use an off board I/V and or filter. The tda1545 board is a bit simpler and has a passive I/V and spots for small coupling caps (Blackgate N series or Nichicon ES 4.7uF.)

The output of the DACs is low and will need some sort of gain stage (tube, opamp, transformer, etc.) though the tda1545's ouput is high enough that in some systems it will work okay on its own.

The tube board is a single 5687 in grounded cathode configuration with a plate load CCS. Output impedence is about 2K, so your next stage should have an input impedence of at least 25K. It would also make a good preamp, and with a little ingenuity can be built up with several different configurations (like a transformer or choke plate load, etc.) Please keep in mind that this project involves high voltages and should only be attempted by someone skilled enough to do so. The tube stage does work pretty well with both the AD1865 board and the 1541 board feeding it.

I have built all of these, so I know they work and I think they sound pretty good, but I can't make any guarantees beyond that. I'll give you a schematic and some basic parts suggestions, but this is DIY so no kits etc. (though if someone wants something totally built, you should contact me and we'll chat.)

I also have a small number of CS8414's, so some boards can come with a CS8414 presoldered.

TDA1541A board: $25 ($37 with a CS8414)
AD1865N board: $25 ($37 with a CS8414)
TDA1545 board: $20 ($32 with a CS8414 -- add $4 for a TDA1545)
5676 board: $25

All prices include paypal charges but shipping is extra. My preference is USPS in a padded envelope, which is generally less than $1.

Images of populated boards are below.

[Destroyer OS.]

About what is the cost of a populated 1541 coming out to be? Then what type of power to throw in?

[dsavitsk]

Sorry for the slow reply. The 1541 board involves 14 blackgate 0.1uF NX caps which is about $25. The chip itself is $15 and up. The input transformer is about $10 at digikey, the resistors, wima caps, regulators, ferrites, etc. probably add $30 to $40 unless you use over the top parts, then it is more like $50 or $60. Oh, and the cs8414 is $12 at Newark. So, $90 at the low end, maybe $120 at the high end.

For power, you need at least +7V and -17V. +8 and -18 is probably better.


For the 1545, you need about +9V (in fact a 9V battery works, though current draw is about 60mA so it doesn't work for long.) Parts for the 1545 probably cost about $40 to 50 on the low end and could go up to $70 or $80.

The 1865 is likely somewhere in between, though 1865's are getting tricky to find. It is not actually discontinued, but Analog says that it is not recommended for new designs and does not show up for purchase from them. It needs +/- 8V, but the current draw is low enough that +/-18V does not stress the regulators too much.

More info, schematics, board layouts, etc. can be found at http://www.ecp.cc/modular_dac.html

-d

[dsavitsk]

I still have 3 TDA1541A boards and 1 TDA1545 board.

[myaudiocables]

I am very interested in a 5687 Gain Stage
Are boards and component lists still available?

Thanks,
Steve

[MONTEFIORE]

dear sir,

i look with interest your dac with 1865 and i enjoy to build it if i could buy a kit.
Unfortunately, i am still enable to send direct mail to the author
amontef@free.fr FRANCE

[dsavitsk]

I have another round of some of these boards.

3x TDA1541A board
2x AD1865 board
1x 5687 Gain Stage board

All are 2oz copper, immersion silver (RoHS compliant). They are also all green now.

$25 each + shipping.

More info, schematics, board layouts, etc. can be found at http://www.ecp.cc/modular_dac.html

Send email to DAC_boards at ecp.cc

I do not have any extra chips, though Digikey does have the basic version of the AD1865 in stock. I also will not supply any other parts.

[A'af]

Just passing by dsavitsk,

i have some IC about dsavitsk design in this link:

FS: assorted NOS DAC part

all the best,
a'af

[dsavitsk]

Remaining boards:

2x AD1865N
1x TDA1541A

[dsavitsk]

A couple of boards still available