[gitarretyp]

I originally posted most of this in the long paradisea thread but got no reply. So, i thought i'd try over here.

I recently picked-up a paradisea and am a little concerned about its behaviour. I was expecting some weirdness at higher frequencies because of the NOS/filterless nature of the dac, but i was playing some sweep tones and noticed there are low level (still audible at my sitting position) artifacts across the spectrum, 20-20k. At lower frequencies, there's a higher tone doubling the lower sweep frequency. At high sweep tones, the second tone begins to warble and is no longer above the lower tone. The second tone is audible with fixed test tones as well, just not quite as obvious. I'm using the dac straight into the amp via the sb's digital volume control, so there's a little bit of sampling frequency weirdness with that, ie when adjusting the volume, the second tone shifts a little in frequency. What exactly would be causing this and is it normal?

Also, paralleling NOS dacs seems to be popular. Has anyone tried similar with the paradisea? If not, is there a technical reason not to do so?

[tanchiro58]

paralleling NOS dacs seems to be popular. Has anyone tried similar with the paradisea?

guitarretyp,

I do not have NOS Paradisea DAC but I listened to it before from my friend. So I can not answer and help you to solve your troubleshooting of your DAC. Let the experts do the job.

In my opinion, the sound of Paradisea was not impressed (using TDA1545A) even though I have MHDT Reneaissance II (using TDA1543) which I did not like the sound in the first couple weeks. But I still love the analog sound of it after couple modifying tips in the signal path. I have had good impression with TDA1543 DAC chips since they sound more analog than 1545A (to me it is analytical). However, after listening to Promitheus SS DAC (using parallel TDA1545A or each channel has one chip-I am not sure) I have a good impression with TDA1545A. It sounds very very analog especially with vocals with seperation and decays (it is still in a break-in time). In other words, the Promitheus DAC so far is the best DAC I have owned before including NOS, oversampling and upsampling DAC. 

We will have a comparison between Paradisea and Promitheus DACs this weekend at my house. So I will let you know.

[Occam]

Gitarretyp,

The first question I would ask is do you find these frequency anamolies when playing those same test tones at the same level with volume controlled by post dac analog controls, ie. a preamp. As you're driving the amp directly from your dac and using your digital source (SB3), there could be an interaction between the digital attenuation when that attenuation is no longer 'bit perfect'. The SB pads nominally to 24 bits, and 'shouldn't' be other than perfect to 16bits unless you're going beyond 8? bits of attenuation. I don't know which build of the software you're using, but Slim Devices has different verions of the software attenuation; nor do I know whether you're doing the digital attenuation in its microprocessor or dac, which I believe you have a choice.

If you get those same anomolies at low volume when controlled in the analog domain, I'd guess it was specific to your dac, but if its only apparent when using the SB's digital attenuation, I'd assume its the digital attenuation algorithm, or its interaction with the specific dac.

I originally posted most of this in the long paradisea thread but got no reply. So, i thought i'd try over here.....

Well, why do you think the Lab would be any different from any other Circle ? I do realize that folks are often apt to forget where they're posting, and we all tend to respond with -
'enough of YOUR problem, you would just be fine if you'd just use xxx (or whatever I currently have a woody for).'

Tanchiro and 1000a - Given the originators first sentance, I can only hope you guys will refrain from the fanboy, mutual admiration society...... in the Lab.

[gitarretyp]

I'm using FW 15 with the latest stable server software. AFAIK, there's only one way to control the digital output; whereas, there are two ways to control the analog output volume. I tried running the paradisea through my receiver and the second tone is nearly inaudible at full volume --had to put my ear next to the tweeter and raise the digital volume on the SB up from a low volume to id the tone. So, it is audible at full digital volume but is very hard to hear. I'd appreciate if anyone else with a paradisea and SB would try a similar experiment (turn preamp volume up and use the sb digital volume control while playing sweep tones) to see if they also hear this tone doubling.

To be clear, this is the fourth dac i've had in my system and the only one to exhibit this anomaly.

I posted in the paradisea thread to see if anyone else owning a paradisea had noticed this issue. I moved the post over here in hopes of getting some technical info on whether this may be an issue endemic to NOS dacs when using digital attenuation or my particular dac.

[1000a]

that is a great list........

sorry I did not pay much attention to where I was

[viperrabbit]

Gitarretyp

I have both the SB3 and Paradisea feeding a Supratek Chardonnay preamp.  I didn't hear any of your problems.
I find that the best setting for SB if using digital out is to disable the digital output volume. Huge difference!
Under SlimServer menu, select SB player -> Audio.  Set the following:
   (1) DIGITAL VOLUME CONTROL - Digital output level is fixed
   (2) VOLUME ADJUSTMENT/REPLAY GAIN - Disable volume adjustment

Try this and let us know if it helps.

[gitarretyp]

Gitarretyp

I have both the SB3 and Paradisea feeding a Supratek Chardonnay preamp.  I didn't hear any of your problems.
I find that the best setting for SB if using digital out is to disable the digital output volume. Huge difference!
Under SlimServer menu, select SB player -> Audio.  Set the following:
   (1) DIGITAL VOLUME CONTROL - Digital output level is fixed
   (2) VOLUME ADJUSTMENT/REPLAY GAIN - Disable volume adjustment

Try this and let us know if it helps.

As noted above, having the volume on full essentially removes the double tone. However, i do not own a preamp, so using it in that mode is not possible.

Have you tried turning your pre up most of the way and using the digital volume control (start low and work your way up) on the sb while playing sweep tones? Depending on your system, you may need to be close to the speaker to hear the doubled tone. I'd appreciate if you could try this and report back.