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The GrubDAC - Page 8

post #106 of 1062
Quote:
Originally Posted by cobaltmute View Post
I suspect that you should be able to do fit a Bantam in this same Hammond case. I did a search, but didn't find anybody doing it (but I might have searched wrong).
I used that case for my bantam (and it may soon be replaced by a grub dac after my next mouser order). The case is the perfect size really. I just took an exacto knife to some of the plastic and trimmed the corners a bit with a dremel though you might be able to get away with just breaking them off with a pair of pliers.
post #107 of 1062
^
I used it for my bantam dac too last year
http://www.head-fi.org/forums/5060945-post302.html

Instead of cutting off the corners, I filed it down a little so it still grabbed onto the sides of the case firmly.
post #108 of 1062
Looks great. It is a nice solution for use as a "cable" DAC.
post #109 of 1062
Thread Starter 
Quote:
Originally Posted by JamesL View Post
^
I used it for my bantam dac too last year
http://www.head-fi.org/forums/5060945-post302.html

Instead of cutting off the corners, I filed it down a little so it still grabbed onto the sides of the case firmly.
Your post says 1551h as the case - I try the Google search for Head-FI and it doesn't come up with your post.

Knew I couldn't have been the first. This case was just a little too obvious of a choice.

EDIT: forum search found it, but Google couldn't
post #110 of 1062
Thread Starter 
Quote:
Originally Posted by dg3f View Post
i am strongly recommending you to add a headphone amp ic part using max9722,it's also powered by a charge-pump ,it has powerful output and low thd+n.comparing with any other charge pump based headphone amp ic ,its price is reasonable while its proformance is not bad(only not as good as Ti's tpa6130,but note that tda6130 is QFN package and not easy to purchase),max9722 must be a good addtion to this project
I was just listening to my 60Ω Senns directly off the Grub. It will drive them, but you can tell the output stage of the WM8524 is not happy driving that low of a load. You get some noticeable harshness in the high end.
post #111 of 1062
Thread Starter 
Just curious if anyone else has managed to build one yet?
post #112 of 1062
Mine's on the bench. I am waiting for a few bits from Mouser, short on time and funds lately. Hope to finish soon. The mouser order has parts for another Carrie to mate with it.
post #113 of 1062
I have two grubs built in two carrie amps. Anyone need two bantams, mini3, alien dac? pm me
post #114 of 1062
Thread Starter 
Take it you like?

It does seem to be very nice with the Carrie.
post #115 of 1062
I've completed one, with another that has a problem somewhere - I suspect it has to do with the PCM2707 soldering as there's no USB detection.

The working one is mated with a Carrie, and sounds pretty good except a slightly harsh top-end with the Shure 840s.

Design-wise, not much to add that hasn't already been said - having an LED next to the USB and SPDIF output would be nice.
post #116 of 1062
Thread Starter 
Quote:
Originally Posted by blippster View Post
The working one is mated with a Carrie, and sounds pretty good except a slightly harsh top-end with the Shure 840s.
Interesting. The 840s are 44Ω. I've got a set of SE210 (26Ω) and a couple generic earbuds (32Ω). I found for these phones that the Carrie+Grub was a little bright and harsh with these, but with my 60Ω Sennheiser HD 440 II, the high end edge disappears and smooths out (or maybe it is the phones).

My standalone Grub is at work so I've got to build another one to do further testing.
post #117 of 1062
Thread Starter 
Quote:
Originally Posted by blippster View Post
I've completed one, with another that has a problem somewhere - I suspect it has to do with the PCM2707 soldering as there's no USB detection.
Is there no detection or does it have an error?

I'd ohm out
  • the D+ line
  • the D- line
  • through R1 to D+
  • and crossing the D+ and D- to see for bridges.

The way I check for bridges on the PCM2707 (and any SMD chip), is to look through my ring magnifier light. I line the pins up I want to check perpendicular to my body and then tilt the board down to see between the pins. I find doing this I can really see what is happening between the pins compared to looking straight down on them.

EDIT:

Do you have power on the board? Check for 3.3V post the regulator. Either end of L3.
post #118 of 1062
Quote:
Originally Posted by cobaltmute View Post
Interesting. The 840s are 44Ω. I've got a set of SE210 (26Ω) and a couple generic earbuds (32Ω). I found for these phones that the Carrie+Grub was a little bright and harsh with these, but with my 60Ω Sennheiser HD 440 II, the high end edge disappears and smooths out (or maybe it is the phones).
Thanks cobalt. It might well be the phones, as it seemed okay during the short listen I had with the ER4S, but haven't really had time to do a comparison with other phones yet.


Quote:
Originally Posted by cobaltmute View Post
EDIT:

Do you have power on the board? Check for 3.3V post the regulator. Either end of L3.
No power post-reg, so that's something I'll check as well when I have some time. Now seems pretty likely I made some silly error somewhere.
post #119 of 1062
Thread Starter 
It is one thing about the board. The LED is driven right off the USB power, so it is an indication of bus power, not board power. I'm adding a 3.3V test point on the next version of the board.
post #120 of 1062
Quote:
Originally Posted by cobaltmute View Post
Just curious if anyone else has managed to build one yet?
Finally got a pcm2707 chip so next mouser order I made, I'll get the rest of the parts. I'll make sure to post impressions once I get it up and running.
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