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Phono Stage Gain Question

I have a Manley Chinook phono preamp.  I'm running a Kiseki Purple Heart cartridge.  All is driven by a Primaluna Dialgoue HP Premium into Klipsch Forte III loudspeakers.  

I have two gain settings on the Chinook.  45dB and 60dB.  By some sort of default logic I have always run things with the higher gain setting, figuring it was needed because I'm using a MC cart. 

Well, the Forte IIIs are pretty efficient so my volume pot rarely went above 9 o'clock or 10 o'clock.  But things seemed slightly congested as I turned up the volume.  Today, I moved the gain switch to 45dB.  Now, I can listen at 68-72 dB (checked with a meter) and the volume pot is at 12 o'clock.  If I want it loud I can listen up to 1 or 2 o'clock. 

My question is--  Is the a soft rule or notion that you should try to get away with the lowest amount of gain possible?  Or given the output of the cartridge should I select the highest gain (60dB) that I have? 

While my ears will ultimately be the guide, it seems like I'm caught between extremes on volume settings.  With 60dB of gain, I rarely move the pot past 9 o'clock and with 45dB I'm going to be running things nearly always at 11-12 o'clock and for louder sessions near 2 o'clock.  Does the position of attenuation matter?  

128x128jbhiller
13 responses Add your response
uberwaltz's avatar
uberwaltz
13,381 posts
 
Traditionally yes the high and low gains are used for mm/homc/ mi carts ( low gain) and LOMC carts ( high gain)
On the Chinook 60db is not really that high by some standards.
What you are really looking for is a setting of gain that does not generate any additional noise or hiss during playback. And if this is enough to drive your amp to adequate volume levels just fine then all is good.
You did not say what cart but I assume from your statements it is a fairly healthy output maybe around 0.4 to 0.5mv.
Dont worry where your volume control is overmuch.
If it sounds good with no obvious hiss then just enjoy.
jbhiller's avatar
jbhiller OP
1,403 posts
 
Hi Uberwaltz!  Always good to see you chime in. 

Yes, the cartridge is a Koseki Purple Heart.  I have 0 hum at 45 dB or 60 dB.  The Chinook is dead quiet--always has been. 

I may just leave it at 45 dB for a few weeks. 
lewm
13,027 posts
 
With the volume control at 1 o’clock you’re not even pushing it at 45db gain. The attenuator is in fact reducing the available signal voltage so as not to blow your head off. So you’re fine.

Would help to know the output of the Kiseki cartridge. Is the Primaluna an integrated amplifier? If so does its line stage provide gain?
uberwaltz's avatar
uberwaltz
13,381 posts
 
JB
Sorry missed the cart entirely in your initial post, doh.
The purple heart is approx 0.48mv output. So yes it is a healthy output to start with.
In theory the less gain you can get away with the better off you should be, less background hash or hiss etc.
millercarbon's avatar
millercarbon
12,531 posts
 
Does the position of attenuation matter?

The answer in general is no. If you really start splitting hairs though.... what's happening in the big picture is you're amplifying a very weak signal in the phono stage, then attenuating it in the pre-amp. Since whatever small amount of noise is in the phono stage, whatever it is there is more of it with more gain. So theoretically at least it should be better to use less gain. Especially since that extra gain isn't really needed, as evidenced by your low volume setting.

Another splitting hairs to think about is the volume control itself. If it really is a pot they are never really perfectly linear and note I said perfect your question is splitting hairs so let's split hairs. There's bound to be situations where the same measured volume output sounds better at one position than another. The same is certainly true of stepped volume where even if every resistor is perfectly matched they will still vary simply by how much signal and how often they are used.

All this crazy technical talk mainly serves to underscore what I say time and time again: Go and listen. You will see. If you hear a difference, great. You know what to do. If you don't- great! You know it doesn't matter.

tablejockey
3,890 posts
 
If you don't notice a loss of dynamic performance, with the lower setting, I say no big deal, unless you had the volume to max, then the amp probably will  maybe have noticeable breakup?
Maybe someone technical will chime in with specifics.
You're driving the amp unnecessarily?


I can switch gain while playing.
Using the MM setting, cranking the volume to match the hi gain setting results in a noisy performance. My phono amp is full tube/active gain. Just too hissy. Also seems less dynamic.
Your Chinook has the advantage of step up for gain and the JFet front end for nice quiet performance, even when cranked. I liked it when I had one, side by side to compare to my phonostage.


jbhiller's avatar
jbhiller OP
1,403 posts
 
Great, great responses folks!  Thanks to all.  I'm going to run things at 45dB for a few weeks.  I really appreciate all of the knowledge. And, Millercarbon, thanks for really diving in here.  Very helpful.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Enjoy your music JB!
jbhiller's avatar
jbhiller OP
1,403 posts
 
Thanks uberwaltz!  I'm the happiest I've been with the system in years, which makes enjoying things much easier.  
uberwaltz's avatar
uberwaltz
13,381 posts
 
That's really great to hear!
Wish I could find that happy spot but I think I am getting there!
lewm
13,027 posts
 
Table jockey inferred that you are using a step up transformer into the low gain input of your chinook. When I read your original post, I don’t see that. If you are not using a step up transformer, I am quite surprised that 45 DB is enough gain for the Kiseki cartridge. Therefore, I think the line stage section of your integrated amplifier is probably adding some gain to the output signal from the Chinook .You haven’t confirmed or denied that so far. That and your amplifier must have a very low input sensitivity, and your speakers must be very sensitive/efficient, indeed.All of this is just technical talk; I agree with the others that you should leave well enough alone.
Post removed 
jbhiller's avatar
jbhiller OP
1,403 posts
 
@lewm , I do not have a step up transformer. Just the Chinook to a Primaluna Dialogue HP integrated amplifier. 
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