Bottlehead Crack w/speedball - DAC question

[crandell25]

Hi,

I just ordered a Bottlehead Crack w/speedball.  I don't have a clue what I am doing in terms of the DIY aspect but looking forward to the challenge!  I am sure the DAC pairing question has been answered numerous times but I currently have two DACs that I could use and I am wondering if anyone has experience with either combo with the Crack.  I currently have a chord mojo driving HD600s but the mojo just doesn't give the HD600s the sparkle I was hoping for, hence the crack purchase.  I also have an HRT Microstreamer for portable use with B&W P7s.  Does anyone have any experience using the HRT Microstreamer or the mojo as the DAC for the crack?  I believe the HRT line out is 2.25V and the Mojo is 3V (which seems a little high).   I am also open to additional DAC recommendations and parting ways with one of my current DACs if a stellar combo exists.  Thanks!

[Deke609]

I used a Chord Mojo with my Crack and even a Stereomour for a while. It sounded great. I ultimately preferred the Schiitt Bifrost Multibit, but not by a large margin.

Regarding voltage output of the Mojo, my understanding is that the 3V "line out" setting (pressing both volume buttons while turning it on) simply fixes the volume setting to give 3V out.  There's a whole bunch of discussion about this on Head*fi - including responses from Rob Watts of Chord.  To get 2V output, I believe you just bump the volume down 3 or 4 pushes - there's bunch of discussion online about this too.

Alternatively, I suppose you could set the Mojo to 3V out and pad the voltage down with some resistors. PB could probably help you with that. You could even build the resistors into a y-cable if you were inclined to build your Mojo-to-Crack cable.

But however you do it, I think you'll be pleased with the sound. The Mojo is very nice DAC.

Just my 2 cents, Derek

[crandell25]

Thanks for the info Derek!  I am glad to hear others have used the mojo/crack combo with success.  I will definitely keep the mojo in the mix then until I get the crack built and do a good trial before potentially looking at other DAC options.  I am looking forward to the build!

[Paul Birkeland]

On the Crack FAQ, there is a recommendation for padding down the inputs a bit with a couple of resistors.  I would buy these and have them ready to install after you have your Crack all the way up and running.  3V is a healthy signal, and there's nothing wrong with using that, but you'll not have much useful volume pot rotation, so the mod is a good idea.  IMO, you could make the 33K resistors 10K and make the 75K resistors 47K to get a pad that's about -16dB, which should give very good control with a 3V source.

https://forum.bottlehead.com/index.php?topic=4295.0

This recommendation makes your 3V source more like a 0.5V source, which is typically what I use to test Cracks here for repair. 

[crandell25]

Thanks Paul, I will take a look at the recommendation!