Variable out in a pre-amp/DAC

[AllanMarcus]

Sorry if this has been discussed, what are the thoughts on using a DAC/PreAmp with a variable out to lower the input into the Crack, and thus allow a little more variability in the Crack's volume, or better allow the crack to be used with low impedance headphones? Heck, what about just setting the Crack's volume to 50%, then using the variable pre-out of the DAC to control the volume?

I'm leaning toward a Maverick TubeMagic, using the non-tube variable output into a Crack (which I just purchased un-assembled on Head-Fi - I'm very excited!). There are other options that have variable pre-out.

[Grainger49]

The input settings have nothing to do with the output impedance and the headphone impedances Crack will drive properly.  There are two tube stages between the input/volume control and the headphone jack. 

As for using more of the Crack's volume there is a sticky that addresses that.

[Paul Birkeland]

I agree with Grainger, if you need more range on the Crack's level control, 50 cents worth of resistors will get you there.

[AllanMarcus]

ok, cool. Now understand that I'm an IT manager with the monkey skills to follow directions and solder. Can you provide a link or information on what resistors and where to solder them?

That said, power amps that have no volume control are controlled by the volume control on a pre-amp. How is that different than using a DAC with a pre-amp style volume control into the Crack?

Many thanks.

[Paul Birkeland]

ok, cool. Now understand that I'm an IT manager with the monkey skills to follow directions and solder. Can you provide a link or information on what resistors and where to solder them?

See #3
There are zillions of places to buy resistors, but I'd look locally if possible (just to save on shipping).

That said, power amps that have no volume control are controlled by the volume control on a pre-amp. How is that different than using a DAC with a pre-amp style volume control into the Crack?

The DAC may actually mess with the datastream to provide volume control, which is not generally well liked. 

[JamieMcC]

I have used the resistor method in several builds it works a treat. Another option that can depend on what music player software you are using to feed your dac is to simple use the volume slider on the pc/music player to reduce the out put. This seems to work on some but not all of my digital sources.

[AllanMarcus]

I have used the resistor method in several builds it works a treat. Another option that can depend on what music player software you are using to feed your dac is to simple use the volume slider on the pc/music player to reduce the out put. This seems to work on some but not all of my digital sources.

So I'm still confused. If I lower the volume in my player, from what I understand that alter the signal and I am not longer bitstreaming the original bits to my DAC, but the volume does get lower through the amp. If I use a variable pre-out volume on the DAC/Preamp, aren't I achieving the same thing, but using the preamp/DAC's potentiometer rather than the volume on the music player?

Also, can you explain what resistors to buy, where to solder them, and possible post a picture or two? That would be very helpful to a nOOb like myself.

Many thanks,

Allan

[JamieMcC]

So I'm still confused. If I lower the volume in my player, from what I understand that alter the signal and I am not longer bitstreaming the original bits to my DAC, but the volume does get lower through the amp. If I use a variable pre-out volume on the DAC/Preamp, aren't I achieving the same thing, but using the preamp/DAC's potentiometer rather than the volume on the music player?

Also, can you explain what resistors to buy, where to solder them, and possible post a picture or two? That would be very helpful to a nOOb like myself.

Many thanks,

Allan

Hi Allan

For the first part I honestly don't know what is happening with the output and bit stream when using the volume control via the slider on the music player but it does work. I kind of assumed it was some kind of digital attenuation rather than physical via resistors. Hopefully one of the gurus here might be able to shed some light on what happens if using this method.

On the second part in the sticky section for the Crack you will find resistor values and instructions for this modification. I don't have a Crack with the resistors fitted at the moment as have changed my volume pot to a different type and found it was not then a issue for me.

Sorry I can't be of more help.

Jamie

[AllanMarcus]

Hi Allan
[...]

On the second part in the sticky section for the Crack you will find resistor values and instructions for this modification. I don't have a Crack with the resistors fitted at the moment as have changed my volume pot to a different type and found it was not then a issue for me.

Sorry I can't be of more help.

Jamie

Big help. It's in the Crack FAQ, question #3.

Crack will arrive tomorrow. I will take it slow, and I have a ton of "honey do" projects on the list first, a few conferences I have to attend for work, and then time to work on the thing. I think I've purchased all the basic items needed to assemble the amp, and a few of the optional items. I guess I just need to get it working, then decide tweaks. Thanks for the help.