The Crack and Full Scale Input Voltage

[williaty]

I think I recall reading somewhere on this forum that the full scale input voltage to the Crack is 2V RMS. The DAC with which I will be directly feeding the Crack has a full scale output voltage of 2.25V RMS. Am I going to need to pad the input (and if so, how? All that knowledge has long since dribbled out my ears) to reduce the output from the DAC to something that won't clip the Crack?

Thanks,
Ty

[Doc B.]

That's what the volume control is for.

[Jim R.]

Also, I don't know how often one actually ever gets full scale output as it is going to depend to a degree on the recordin level, compression, etc.

I've got plenty of albums with really great sound, but are at a pretty low  level -- far below the norm.  Ry Cooder Vishwan Mohan Bhatt, "A Meeting by the River" is one example off the top of my head.

As for the situation with your dac and the crack, best bet is to just listen to your typical music with your cans of choice and then figure out if padding the input would be a good thing, then you can measure (subjectively as I don't know how you'd measure actualSPL in a headphone), and then refer to PJ's paper on signals and snr in the technical talk area.  I'm betting it will still take some trial and error even once you establish a theoretical attenuation value -- but I myself would consider that fun :-).

Can I ask what dac?  Sounds like one of the AudioGD dacs to me, or maybe an HRT.

Good luck,

Jim

[Laudanum]

I asked a similiar question in an existing thread.  My main source has 2 volt output.  But I grabbed the old AH Tjoeb 99 CDP from another system to add as a source for the Crack.   The reviews for the Tjoeb (a decade ago) state output voltage at a very hot 3.5V.  But as Jim says, it would really depend on the level of the CD as well.  And with a hot CD I'd never come close to cranking the volume knob on the Crack.  With a very cold CD, output voltage wouldnt get near 3.5V.  Even with Hot tracks on the 2V source I dont go beyond 12 or maybe 1 oclock and that's too loud for long term listening (and probably short term).  Personally, Im not worried about padding the input.  I think my own good sense can take care of the volume level. 

[williaty]

While I was driving my wife around to home crap stores tonight, I had some time to think about this and realized that I'd probably never turn it up far enough to clip it, regardless of output level of the source, due to the fact that I don't like loud music. That assumes the volume control attenuates the input, and replies here make it sound like it does.

Yes, it's a High Resolution Technologies (HRT) MusicStreamer II+ (2010 model). I'm VERY impressed with it.

[Laudanum]

As Paul J. states, the "volume" control is actually a gain control.  Input is attenuated up until that volume knob is turned all the way clockwise. Obviosuly less attenuation the further you turn the know clockwise.  One problem may be too much volume too soon relative to the volume knob.  But I havent experienced that problem with the 3.5 volts out of the Tjoeb 99 CDP (Alps blue velvet pot) so I dont think a 2.25 volt source will be an issue there.

[Jim R.]

Good choice on the HRT MSII+ -- I've got onne myself and like it a lot.  I just had mine cryoed and am doing some other tweaks as well as a nice heavy mounting base made of jatoba and maple, which is both for pimping it up and keeping the tail from wagging the dog with heavier interconnects and usb cables.  I certainly wouldn't do that if it weren't a keeper.

-- Jim