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How much gain is needed in a Phono Preamp for a 0.2 to 0.3mv low output moving coil?

I have been out of audio for 25 years and am now getting back into getting a system. I have looked at Manley Chinook, Ear 834p, and Audio research 5, 6, 7 Phono preamps, after reading thru many or post on Audiogon. All have about 57db gain to 60 bd gain. I have been looking at getting either a Dynavector 10x5, Benz micro Silver, Ortofon Quintet Black, or a used Benz Ruby Z (if I can find the money). Is 57db enough gain for the cartridges. I would also welcome feedback on the Phono Preamp. I am leaning toward the ARC PH7 or Manley. Either would be around the same price. I would prefer to stay with tubes. The turntable is a VPI Prime. Any help or opinion would be greatly appreciated.
128x128juke4u
almarg's avatar
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almarg
9,670 posts
 
With the Herron  you have the added advantage of being able to easily switch from 64 to 69 Db of gain just by swapping out two tubes.
I'm not sure that is true, Analogluvr.  I believe I recall someone stating in a thread some time ago that he was told by Keith Herron that there are circuit differences between the two gain configurations, in addition to the differences in tubes.

In any event, as you, I, and just about everyone else who has heard it and posted about it has found, it is a remarkable performer.

Best regards,
-- Al
 
analogluvr
859 posts
 
 No I spoke with Keith herron himself who told me that. I have done it multiple times to no ill effect. 
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almarg
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Thanks, Analogluvr.  Good to know.  What I was recalling may have been the second of the two posts dated 4-22-2013 by member Czbbcl in this thread.  Apparently he was wrong.

Best regards,
-- Al
 
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atmasphere
11,809 posts
 
If the noise floor is low enough 57 db might be fine.

But the phono gain isn't the whole thing. The gain in the line section, the gain in the amp and finally the efficiency of the loudspeakers all make a difference!

So if you have 57 db, a passive volume control and 89db speaker it won't work in most cases. So you need to add up the gain in the electronics and see if that will give you enough sound pressure.
dcbingaman
93 posts
 
How much gain for 0.2 mv MC ?  It depends on the gain in your line stage and your amplifier, but I would say 60 db is a good starting point....I wouldn't go any lower, unless your line stage has 15 db of gain or better itself.  If you use a buffer / unity gain line stage (First Watt B-1, etc.), then you need more like 75 db.  The Pass Phono (XP-15 and XP-25) stages can provide that much gain with very low noise.  

Most toob phono stages give 50-60 db, and the quietest ones either use a step-up transformer or JFET's on the input stage (like the Pass solid state designs).  55 db is enough for a normal 0.5-0.6 mv MC, but marginal for a lower output cartridge.

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