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Gain Structure help, Mcintosh D100 to Primalune tube amp

Need to adjust the gain structure, D100 (used as DAC and pre) outputs 0-8V and Primaluna has 1.2V input sensitivity.

I can adjust the source input gain (PC via USB to the D100) which will allow me to use the D100 volume control at more than 50%, but I have heard this is not the best way.

Or should I try some attenuators (12db - Harrison Labs) on the output of the D100 going into the Primaluna amp.

Thanks
johnziomas
johnziomas's avatar
johnziomas OP
40 posts
 
Hi George,

I spoke with Ron at Mcintosh, and he said they are using an analog volume control and there is no bit stripping or any advantage to try to attenuate the output of the unit.  Essentially my range is up to 50-55% (hard to tell with the Primaluna amp if it is clipping at that point or what, but it is plenty loud) which I can live with.  Unit/system does sound amazing even at low levels (20% or whatever) just wanted to make sure I am not leaving anything on the table.

any thoughts?
georgehifi's avatar
georgehifi
4,966 posts
 

You maybe right, because the manual I looked at said

"0 to -60db digital volume control"

Maybe I looked at another model by accident. If this is correct then you have no trouble going direct no mater how low the volume is.

Here are some pics

This one shows the VC on the right, connected to the digital side of things

http://www.avmagazine.com.hk/common/createthumb.asp?w=640&h=480&p=/image/content/personal/D100_640.jpg

This one shows the analog output board and analog outputs on the left with the selector switch attached to it.

http://www.audio-activity.com/uploads/1/3/0/9/13098779/_9628528_orig.jpg

The only pot that goes to this board is a selector switch, if the VC is analog it should go to this board, not the digital board. Makes me wonder now. I guess they know??

Cheers George

georgehifi's avatar
georgehifi
4,966 posts
 

Hi John, just found this out for you, looks as though the front right panel knob is digital in the way it send the coding onto the analog side of things. "maybe"

Quote from "The Ear" review

"Mostly the output mode is chosen with the use of DIP-switches or through software. Volume control takes place in the analogue domain within a special chip driven by impulses from the front panel rotary knob."

Maybe you can set this front panel vc low for your max you want (preset), then use the remotes vc as the master vc, if indeed it is analog??

Like I said before Mac can do some crazy things.


Cheers George

georgehifi's avatar
georgehifi
4,966 posts
 

What Mark Levinson and Wadia did in their great R2R Multibit dacs/cdp of yesteryear, was to use a digital domain VC, which is the best if you don’t "bit strip"

But they allowed and instructed the user to get the best sound was to set with bridges across small two pin connectors the amount of gain the analog output stage had 10 different levels from 1 to 5v each channel. So then you could use the digital VC at or down to 1/4 below full output.

Very smart they knew about "Bit Stripping" before it was even named


Cheers George

johnziomas's avatar
johnziomas OP
40 posts
 
Thanks so much George,

this is interesting, I'll test tonight.  I'm almost certain though that the remote's VC and the knob act the same, just by judging at the percentage of volume shown.

I'll check it out and thanks again. 
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