[Postal_Blue]

I know your crazy busy atm jon but the link is dead for me.

I too am in the "oops I forgot l2f" camp. I will be placing an order with mouser in the next day or two for another build and will be tacking on the inductor. If anyone finds themself in this situation, let me know, no need to eat shipping on a .17 part.

 

[Fishline]

Even though this is a DAC question, I think there must be other newbies like myself who are interested in this: Can some kind soul give a summary of differences between the Bantam and the Grub, especially with respect to Carrie? I'm trying to decide which one to go with.

 

[ShinyFalcon]

There are less parts on a Grub, and can be more appealing to a beginner. Otherwise, the only difference is between Texas Instrument and Wolfson, and whether one prefers simplicity (Grub), or slightly more discrete and customizable (Bantam). I don't know which of the two draws less current, but if the problems with the Carrie overloading the computer's USB port is fixed then there shouldn't be too much of a difference between the two.

 

[cobaltmute]

Quote:

Originally Posted by Fishline /img/forum/go_quote.gif Even though this is a DAC question, I think there must be other newbies like myself who are interested in this: Can some kind soul give a summary of differences between the Bantam and the Grub, especially with respect to Carrie? I'm trying to decide which one to go with.

The main difference between the Bantam and the Grub is the signal chain on the board. In the Bantam, USB and DAC functionality are handled by one chip, the PCM2702. In the grub, this is handled by two chips, the PCM2706/7 and the WM8524.

The PCM2702, outputs mid-rail DC (at 2.5V), requiring the use of blocking caps to ensure that the DC doesn't not get into later components. The WM8524 is a ground referenced DAC chip. It uses a charge pump internally to create a negative rail and then references it output to ground, requiring no output caps.

Output caps "color" the sound, which is why many people chose different caps for different reasons. I'll make no claim as to which sounds better, they just sound different. Considering both can be built for a low cost, it is up to you to decide which you like more.

From a practical build perspective, the Bantam uses a standard large USB B connector, while the grubDAC uses a mini-USB. The grub has a header spot allowing for easier pulling of the 5V and the GND to carry onto the Carrie PCB.

Also from a practical build perspective, the grub is currently out of stock at Beezar. We've run out of proto's and are about to order the production boards.

 

[Fishline]

Thanks a lot, Cobaltmute and ShinyFalcon, for the very useful info! I will try to catch the grub production board bandwagon then. Should I keep my eyes on the grub thread in the diy forum, or will there be a GB thread, or something else?

 

[cobaltmute]

It will be announced in the grub thread when the boards are in stock at Beezar. Very shortly some pictures of the final board will be posted in the grub thread.

 

[keyid]

i tried both with the carrie; get the grub!

 

[joneeboi]

Quote:

Originally Posted by varione /img/forum/go_quote.gif Did anything else change from the BoM besides the missing L2F? I guess I should have waited to order...stuff just came in today for bantam and the carrie. I just copied the BoM exactly and only ordered one of the inductors. Are you able to add-on to backordered parts at mouser or will I just have to place a new order?

Quote:

Originally Posted by Postal_Blue /img/forum/go_quote.gif I know your crazy busy atm jon but the link is dead for me. I too am in the "oops I forgot l2f" camp. I will be placing an order with mouser in the next day or two for another build and will be tacking on the inductor. If anyone finds themself in this situation, let me know, no need to eat shipping on a .17 part.

If you forgot a part, send me the money for the part and I can order it and ship it with your PCB.

The link was dead because I was fixing it. The BOM should be fully operational now. I still have to add the international part numbers, but I have to juggle all this money coming in now.

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif I don't know which of the two draws less current, but if the problems with the Carrie overloading the computer's USB port is fixed then there shouldn't be too much of a difference between the two.

I didn't see this problem until I hooked the Carrie USB Headphone System into a friend's Macbook. I can't guarantee this, but I believe using a 1W DC-DC converter may fix the problem. IIRC, the one I used had a 2W converter. There's plenty of capacitance to make up for huge instantaneous current draws, so a 2W may not be necessary. Turning off the amp before plugging it in may also fix the issue, but I don't know until I can test it on his computer. All the PCs I've plugged it into haven't complained so far. The max current draw from the PCM2702 is 225mW and that of the PCM2707 is 242mW, so going with a 1W DC-DC converter should keep you safe. And even if you used the 2W chip, you should still be within USB 2.0's limits. Anyone else care to chime in?

 

[Juaquin]

Well I have a current-gen 13" MBP so as soon as I finish my Grub this weekend I'll let you know. I also have access to dozens of computers (Mac, PC, laptops, desktops) where I work so I'll test that out next week.

 

[cobaltmute]

If you recall I have an issue with a 2W DCP Carrie, grub, Windows 7 and Thinkpad X61. The port will end up disabled by Win 7, but if you re-enable it works. When I put a meter in between with peak hold, the combo pulled IIRC 800mA to start. I have one USB cable (from an iRiver) that it works with. This cable has a ferrite on it. If I use I dual power USB (two USB A to one mini-USB), I'm fine as well. On a similar hardware X60 with XP, it shows an error that the amp pulled to much power, but leaves it enabled.

I think the issue is around timing. The voltage regulator is in drop-out while the DCP is starting up. This allows more current through than some USB power management switches tolerate. It is then up to the OS to decide what to do.

 

[joneeboi]

New board pictures are up.

 

[Swimfar]

Do you have any dimensions for the face plates? If not I think I can come up with an approximate layout using data sheets for the pot, output jack, and usb jack. I have access to some tools right now that I may not have in a few weeks so I want to make up a few face plates while I have the chance.

 

[pistolsnipe]

i believe that the front plates are the same as the mini 3, there are dimensions on amb's site

 

[cobaltmute]

DKJones96 had posted some FPE files before, but they are not on the hosting site anymore.

These are the files I did my panels with the grubDAC proto boards. At least on the ones I ran, they were up a fraction high, so if I were to run the boards again, I would move the holes down a smidgen.

Give me a couple of days and I'll post updated files that have the USB connector in the right spot for the production grubDAC boards.

 

[joneeboi]

Quote:

Originally Posted by Swimfar /img/forum/go_quote.gif Do you have any dimensions for the face plates? If not I think I can come up with an approximate layout using data sheets for the pot, output jack, and usb jack. I have access to some tools right now that I may not have in a few weeks so I want to make up a few face plates while I have the chance.

Quote:

Originally Posted by pistolsnipe /img/forum/go_quote.gif i believe that the front plates are the same as the mini 3, there are dimensions on amb's site

Pretty much copy the Mini^3's faceplate minus the input jack and you should be good. Consider that I used to call this project the Bus-Powered Mini^3. I tried as much as possible to mimic the position of the pot and output jack.