You cannot really extrapolate from one system to another to estimate the needed phono stage gain, especially if the line stage is passive. But amplifier input sensitivity, and speaker efficiency also play important roles. Anyway, the OP cannot break anything by trying different gain settings. And it seems likely that somewhere between 42 and 46d B gain is going to be ideal.
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I am using a SS Carmen II, which is the same output voltage as your cart. (2.12 mV) and running it into an SPL Phonos using the 46 db gain setting. Works great, plenty of headroom without overloading. I'm using a passive (Hattor Audio) preamp so no extra gain there.
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@tablejockey re: "There shouldn't be any lack of bass with the JBL's." You might want to edit that to say 'mid-bass' as the L100 starts rolling off steeply around 55Hz. It's also a high-Q design with a peak of 6dB or more so an octave above the port tuning frequency. Low bass was never a capability.
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"I’m not sure if the JBLs are anywhat of a good match for the Primaluna but I got them for dirt cheap at an estate sale so they are staying for a while."
nmo25- I bet the JBL's will sound good, if you like the "vintage sound"
Vintage sound to me is not overly detailed, overall presentation leaning on the warm side. There shouldn't be any lack of bass with the JBL's.
You might be able to fine tune the JBL's tone with the 2 gain tubes on the PL.
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I tried all the recommended MM levels on my Schiit Mani and Freya with a Grado MM. Two levels sounded good. One was a better match for being similar to my digital rigs channel, so I'm using that. (I should note there was a distortion before the unit and cables burned in, so if yours is a new set up, do a burn in on the Mani). |
You don't really need to worry about any math equations, because you have a combination that cannot fail to provide enough gain up the chain, and because you cannot damage anything by experimentation. But if you insist, there are excellent calculators for converting signal voltage to db and vice-versa, on the internet. There may be one on the KAB website, for example. For what it's worth, I am running an MI cartridge with output similar to that of your cartridge into a Manley Steelhead, with no added gain downstream from any linestage. I find the 55 db setting on the Steelhead works fine. My amplifiers seem to have a very high input sensitivity (meaning, full output is achieved with much less than 1V input), which helps. In your case, because you do have an active linestage section that adds 12db, according to others who posted here, probably 48 or 50db is a good choice. |
Tablejockey,
Of course! I wanted to see if I was in the right ballpark before messing around and finding out what sounds best. I haven’t bought the soundmith cart yet, but the compliance works well with the lighter VPI arm so my next bet was to see if the output would be close to one of the gains on the mani.
Obviously my phono stage is the bottleneck in the system, and eventually I would like to upgrade that. I appreciate the tube preamp recommendations because that’s definitely the path I’ll be going down. I’m not sure if the JBLs are anywhat of a good match for the Primaluna but I got them for dirt cheap at an estate sale so they are staying for a while.
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I’d agree that he’d realize huge performance gains going to one of those fine tube/hybrid phonos over a budget SS like the Schiit. I have the Herron and a VAC Renaissance after upgrading through phono stages for years; both are absolutely fantastic. The Rogue Ares (and probably their new Triton 2) is also very very good for much less money, but those more expensive units are certainly better. |
nmo25,
I HAVE the PL HP, a VPI,and used a Schiit Mani, while my main unit was in the shop.
Don't drive yourself mad figuring what is "absolute" on paper.
One of the 2 first MM settings will be fine. Using your ears, in this instance, won't damage anything.
The Mani is a great entry level, cheap unit. In my case, it served as something to get by with, while waiting for my "proper" phonostage to be repaired.
Your system is being underserved. With that amp,table/cart and speaker setup, you're only hearing 60-70% of what it's capable of.
Consider a Chinook or Herron, they seem to be the 2 most popular tube based units here. Use a tube phonostage to keep the tube vibe(realistic/convincing) presentation. You have that PL(tubed) for a reason.
Naturally, this is IMHO. |
Go to vinylengine.com and use the tools there to calculate gain requirements. |
My Herron mm phono amp provides 42dB of gain, which works fine (to use understatement ;-) with my 5mV output London cartridges. I don’t know how Schitt came up with 30dB for Deccas, but remember, 5mV is the cartridge’s nominal output, not it’s maximum. Transient peaks may produce even higher output, right? Another phono amp incorporating a setting specifically for Decca/Londons is the Andros by Zesto Audio, whose impedance switch includes 15K ohms (the cartridge likes to be loaded down, to electronically damp it’s high frequency resonance). Zesto designer/owner George Counnas told me he put that in the Andros specifically because of all his friends and industry colleagues who use Decca/Londons, a cult favorite! |
Really, anywhere in the range of 0.5 V to 1.0 V output from your phono stage (calculated by specs; peak levels can be much higher) is typically fine. I tend to like it in the hot side towards 1V in practice, but you run the risk of cutting into overload margins of the phono stage (varies by model) that way. |
I appreciate the discussion and I am trying to wrap my head around this.
So to find the correct phono stage gain gain ‘on paper’ for a cartridge with 2.12mV output would I assume the phono would output a voltage of ~1V line level?
Vout =1V
Vin =.00212V
Phono stage gain would technically be 53.5dB ?
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Well 40 dB on 5 mV is only 0.5 V. While 30 dB on 5 mV results in an absolutely anemic (for line level) 0.158 V. You pipe that into a preamp next to an input holding a hot digital source of 2V - 4V (e.g many balanced DACs), and you’re going to have to be careful to remember to turn the preamp volume way WAY down when you switch from vinyl to digital. I would never even attempt such a setup. |
In the specs for the Mani on the Schitt website, the 30dB gain setting is called "Decca Mode’. Decca/Londons produce a 5mV signal. Make of that what you will. |
You need to match phono stage gain to the cartridge first. Don’t get tied up in the integrated’s input sensitivity, which is spec’d at the point where the volume control is WIDE OPEN, and determines the amount of input signal required to output the full rated power. This is not indicative of how you will likely use the amp. You might better think of your integrated as like a preamp that has a gain of 12 dB (250 mV to 1 V line level) plus a power amp section of 1 V sensitivity and 25 dB gain (40 Watts full power from 1 V input). Which makes for a total of 37 dB gain (volume wide open).
Your cartridge is 2mV. That’s 8 dB less output than a standard MM cartridge of 5mV. Since the typical MM phono stage is 40 - 42 dB, I would be inclined to try the 48 dB setting for your cartridge. In practice I find I often like a little extra gain from my phono stage, but you will be cutting into overload margins at some point (which may explain the prior poster’s experience at 48dB with 5mV on the Mani). Regardless, 48 dB is a great starting point for you “on paper”. |
I too have a Mani and for cartridges with 4-5 mV of output, which mine are, the 42 dB setting is ideal. I tried the 48 dB setting and the soundstage collapsed and was far more compressed. Can’t hurt to try it though and see if you get the same result.
The Soundsmith Otello has an output of 2.12 mV.
Go with 42 dB. |
