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Phono stage and preamp overload

I’m in the process of setting up my first analog rig (i.e. trying to rely upon my digital gear for ease and building an analog system that’ll offer a different experience).  I’ve read as much as possible without asking some questions, so here goes…Basically, I’m trying to understand how to set the phono stage at an appropriate gain such that my line stage is not “overloaded”.  

 

Here is my relevant gear and numbers:

Line Stage - Bel Canto Pre3 (input voltage overload = 10 vrms; gain = 20 db)

Phono Stage - Pass Labs XP-17 (gain of 50/60/70 unbalanced or 56/66/76 balanced)

Cartridge - Dynavector 20x2 (0.5mv)

Amp - Pass Labs x250.8 (2.24 v at full gain; not sure if this is relevant or not)

 

I’ve read that dB gain = 20 log (Vout/Vin).  How do I calculate the appropriate phono gain so that I retain a reasonable amount of headroom and don’t overload my line stage?  My simple math leads me to setting a phono gain of 66, or 20xlg(1/0.0005), but I have no idea how that relates to the input voltage seen by the line stage nor do I understand whether or not Vout = 1 is the correct value).

It seems easy, but I remain perplexed…please help an analog newbie escape digital!

mikek1
millercarbon's avatar
millercarbon
12,531 posts
 

You are seriously over thinking it. Especially since overload is much less likely than having too much. Your typical phono stage with 45 to 65 dB gain will output a normal 3 or so, right in the sweet spot of your preamp input range.

The volume range on virtually all preamps is so wide it just isn't a problem. Almost always, the worst that will happen is you have to turn the knob a lot more, or a lot less, than with your line level sources. This is where you stop and remind yourself, the position of the volume knob means nothing. It is nice if all the sources are at about the same level, because then you don't have to fiddle around as much. But that is pure convenience and nothing to do with sound quality. Do it a time or two, you will see.

mikek1 OP
13 posts
 

Thanks, millercarbon.  Truth be known, your passion for analog and distaste for digital factored in to me going down this path.  Your input/insight is much appreciated.  Best,

millercarbon's avatar
millercarbon
12,531 posts
 

Well the stuff you have listed there is excellent. I would lean Koetsu but in truth once you get much over a grand it is hard to find a bad cartridge and a good one at this level is really good. They do keep getting better but already you are at a level where it pays big time to put that cart on a top flight arm and table. Frankly the table and arm are more important. Especially once you have an excellent phono stage, which you do.

(I’m not sure if this is what you have or what you’re considering?)

What table and arm are you using?

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