Alien DAC v1.1 Construction Thread

[Alf]

Quote:

Originally Posted by Sinbios How is the USB 5v output related to the formula Vout = (1 + R31 / R32) * Vref?

You need to make sure that Vout < Vusb - Vdrop if you use USB for powering your DAC. Otherwise the regulator does not regulate.

 

[tomb]

Quote:

Originally Posted by doobooloo Since the BGs I wanted were out of stock at Kyoto, I went to Sonic Craft. They were a real pleasure to deal with, and I got my shipment promptly. www.soniccraft.com You have to email them with your order and they'll call you for your credit card information. Kind of old school, but it works and their service is very professional! I got a few other parts from there too, no problems.

How in the world did you get enough response from Kyoto to even know they were out of stock? MisterX called it - no reponse, nothing, nada.

I saw your earlier BOM with SonicCraft listed, but chose to go with Kyoto because they were web-order-capable. Live and learn, I guess.

 

[Pappucho]

Don't forget Percy Audio when looking for black gates. I've had nothing but good experience with them and they have a wide selection.

 

[doobooloo]

Quote:

Originally Posted by tomb How in the world did you get enough response from Kyoto to even know they were out of stock?

Uh, their webpage for BGs shows them as not in stock. So I didn't order.

 

[mb3k]

What are your guy's soldering method of choice for IC1 (SSOP28).. flood and suck?

 

[doobooloo]

Quote:

Originally Posted by mb3k What are your guy's soldering method of choice for IC1 (SSOP28).. flood and suck?

Pin by pin soldering for me...

 

[DaKi][er]

Quote:

Originally Posted by mb3k What are your guy's soldering method of choice for IC1 (SSOP28).. flood and suck?

(flux) Paste and Draw (iron across the pins in one sweep)

 

[MisterX]

Quote:

Originally Posted by DaKi][er (flux) Paste and Draw (iron across the pins in one sweep)

Agreed.
That works much better then the flood and suck routine

 

[MASantos]

When I built the revision A DAC I used the flood and suck technique, but the prototype board I used "paste and draw" and that worked much better! It is faster, cleaner and the IC doesn't get as hot as when using flood and suck technique. I would recomend this technique to everyone!

 

[tomb]

Quote:

Originally Posted by doobooloo Uh, their webpage for BGs shows them as not in stock. So I didn't order.

Hmm - I don't think that was there when I ordered. Regardless, MisterX is correct - lots of e-mails and no response. I'm giving them until the end of the week, then will contact Paypal to start the dispute process.

The boards look great!

 

[Buzzerbro]

Regarding the CL and CR capacitor positions, what would be better, the 47uF/16vdc Nichicon Muse ES or 47uF/25vdc Nichicon Muse KZ ? Size nor cost is an issue for me.

 

[peterpan188]

Quote:

Originally Posted by Buzzerbro Regarding the CL and CR capacitor positions, what would be better, the 47uF/16vdc Nichicon Muse ES or 47uF/25vdc Nichicon Muse KZ ? Size nor cost is an issue for me.

I think KZ is Nichicon flagship. According to most others, ES is very bassy, but not as detailed. KZ is little thin in bass from my experience, but they do quite much up the Blackgates, except for the special smoothness I got from the BG.

Regard,
Peter

 

[Whitewind]

From the looks of REG101 and REG102 (adjustable) datasheets, it seems that Vref is 1.267V and 1.26V respectively. On Alf's site it is indicated as 1.26V and 1.1267V respectively.

I'm not sure about this, but if someone could double check that would be great.

Also just a question, would there be any problems by adding a 1.2V NIMH AA in series with the usb supplied voltage?

 

[Sinbios]

Whitewind: I thought about that, but I can't think of a way to make the DAC draw most of the current from the USB and only use the battery to boost voltage.

I've actually been puzzling over the power supply most of the afternoon. Assuming the USB gives perfect 5.0V (which mine does), going by direct USB regulated, the regulator wants input voltage = output voltage + 0.4V, which gives a maximum output voltage of 4.6V. Beyond that the ripple rejection drops off significantly, however the regulator will benefit from a voltage difference of even 1V between the input and output voltages. The DAC chip's minimum working voltage is 4.5V, and performance gradually improves as voltage increases, up to 5.4V.

The ideal situation for USB power would be to take the 5V from USB and step it up to 6.4V, and then regulating it to 5.4V and feeding it to the DAC. I looked up a few voltage converters today and this is certainly feasible, maybe for the next revision?

The alternative would be to hook up say, an NiMH AAA in series, which boosts the voltage to 6.2V, and regulating it down to 5.4V. Problem with this is the battery would only last about a week if the DAC is running 24/7. One idea was to limit the current draw from the battery somehow, but I can't figure out a way for when the battery is hooked up in series. Anyone with some insight on current limiting?

The other idea was to build a trickle charger into the DAC and charge the battery from regulated USB - another idea for the next revision, perhaps?

 

[robzy]

Quote:

Originally Posted by MASantos When I built the revision A DAC I used the flood and suck technique, but the prototype board I used "paste and draw" and that worked much better! It is faster, cleaner and the IC doesn't get as hot as when using flood and suck technique. I would recomend this technique to everyone!

What exactly is the past and draw technique?

Rob.