Soekris DAC2541 information and impressions thread

Hi folks,

This has been up for several days on Soekris.dk, but some of the links were broken so I held off on posting up here. It seems they have sorted that out now, so here goes:

http://www.soekris.dk/dac2541.html.

Congrats on getting the new flagship out the door!

(It looks like the image tag is not working right now, so I'll update with images later. Images still broken, may be my side.)


In short, this is physically very similar to the DAC1541, housed in a basically identical case, but with some key changes under the hood. Essentially we have a new set of resistors, giving us 28 bits vs 27 bits in the DAC1541, and apparently some updates to the power supply (though that may already be on later DAC1541-mine is one of the early ones with the 3 prong IEC power socket). It looks like they have switched from the Spartan to a Lattice FPGA with updated firmware, but there is no detail yet on if and how filters may have changed. The unit loses the USB Audio 1/2 switch as well.

@soekris perhaps you could give us an inside rundown on what has changed both technically and sonically?

I'm not sure if I'll bite one of these...waiting for some impressions to surface.

 

Also, doesn't seem to be fully differential anymore, only 2 resistor ladders (one per channel) vs. 4 (two per channel) on the dac1541.

 

I wish it was just a DAC. I hate paying for things I will never use (looking at you Hegel).

 

Yup, looks like you're right - the manual refers to more than 200 resistors where the DAC1541 manual refers to over 400.

 

The headphone amp is just the DAC output stage with class-A bias increased. Not much extra.

 

The dac 1541 measured worse balanced vs SE per atomicbob (the speculation was summing issues?) so maybe the new one's simplifying the design by having a higher resolution SE DAC with balanced out done in the output stage ala Bifrost 2. Quite sensible.

 

FWIW the DAC1541 stages differently BAL vs SE, and SE is better to my ears and a couple of others here. It does use all the ladders though even SE.

 

Just look at it his way: Is the dac2541 worth EUR 1100 ? The built in headphone amp don't really add much cost....

 

The dac1541 buffer stage is used both for line and headphone output, just with higher bias. The stage is a fully differential input and output, so SE and Balanced should sound the same and have same noise....

On the dac2541, there is a separate headphone amplifier, a classic composite with a opa1656 and discrete diamond buffer.

 

ok, it's correct that the dac2541 reuse the case design, otherwise the differences are:

There are just two R-2R networks in the dac2541, they have then been improved, and have better voltage references. The output buffer creates the balanced output, and are using the new TI opa1656 cmos opamp. The headphone amplifier is separate, a classic composite with a opa1656 and discrete high bias diamond buffer.

The FPGA have been changed to the significant larger Lattice LFE5U-45. Still use 4K filters, but at some point I will increase the number of taps.

The USB Audio Mode 1/2 switch is gone, seems everybody is running Mode 2 anyway.

The dac2541 calibrate itself on power up, reduce THD a little and make it more consistent, and make it possible to use less precise resistors.

Power Input Plug is IEC8, just like the latest dac1541.

Firmware can be update without opening the case, have a built in USB to Serial port using the same USB connector as for Audio.

All result in lower manufacturing cost and sale price....

The sound is still the same principle, reproduce what comes in without changing the sound. People who have listened to a dac2541 say it's very musical and clean, the best from analog records and CDs.

I'm shipping one to Marv to go on a tour.

 

Not to threadjack, but I'm looking forward to details and availability on the dac1221, if/when you can provide.

 

Have hardware, working on the firmware right now, soon have something after the weekend.... Maybe for a new thread ?

 

From the posted internal picture of the unit, am I right to understand this new model only has 2 sets of ladders, and it isn’t fully balanced ladder architecture internally, unlike the dac1541 which has 4 sets of ladders?

Following your original model number format, I suppose it’s more like a dac2521.

 

Correct, as I said a couple of posts ago, only two sets of R-2R resistor networks.... The model number xx41 really means balanced out....

 

Just to sate my curiosity, can the filter sets on diyaudio still be loaded on the new 2541? Like the pseudo-NOS one etc.