Increasing gain for your vinyl front end when pre-amp doesn't quite have enough juice

Hi Folks, just wanted to get your thoughts on what route you would go if your pre-amp (I’m talking about a normal pre-amp, not phono preamp) doesn’t quite have enough gain for very high listening levels for my turntable set-up. Now, on my phono-pre amp, there is a setting for maximum gain (schiit Mani) up to 59db, but the S/N ratio takes a hit and goes down to 70db, however, it does pump out the needed volume. What about the idea of putting in a good (inexpensive headphones amp/preamp - one of those $99 guys - like schiit Magni, JDS Labs Atom or Monolith Liquid Spark) between the phono preamp and the regular preamp? Does this have the potential of producing the needed gain while at the same time not degrading the signal too much (perhaps not as much as full gain on the Mani?) Just wanted to see what you all think. To me it seems like less items in the signal chain the better, but if it has a higher S/N ratio could be a better option? (with the added benefit of listening to vinyl through headphones, which I’ve never done before.)
higher output cartridge, assuming your preamp has no adjustability and you have no interest in adding a phono pre.
Love my cart (nagaoka MP-150 I spent a long time researching and trying different carts already) and love my current phono-pre and not interested in spending more than $150 to 'fix' the issue. Between upping the gain on the mani or buying a headphones amp, what would you choose?
At 4.5mV output on your MP-150, you’ll likely be running way to close to the overload margins of a phono stage running at 59 dB - especially a budget phono like the Mani. So in your case, yes adding a headphone amp with a net gain of around say 10-20 dB (careful to find an optimal volume position for whatever you choose) and running the phono at a lower gain would be much more optimal. But it’s still less optimal than just running a single preamp with a good gain structure for your system.

Doesn't your Mani have a 48 dB setting? that should be optimal for your MP-150. If your system is lacking gain at that setting, then ideally you need either more gain in your preamp, more gain in the amp, or more sensitive speakers. 
Up the gain. For when you really need the volume.

The other idea, putting a very low voltage and RIAA equalized cartridge signal into a device designed for line voltage, not to mention adding another interconnect to screw things up, and I'm not even gonna start on grounding issues this mess might cause. You think a little white noise is a problem? You will just have try the headphone amp to appreciate the awfulness of that one. All those scores of step up transformers? The complete lack of headphone amps marketed as step up transformers? Think about it.

What cartridge are you using? What is it's output voltage?
From your post, I am not quite certain what you are using now, except it's a Schiit Mani.  If at least I got that right, is the Mani a phono-only unit or does it include a linestage, which is to say, can you plug your CDP or TV into it as well, which would indicate it has a line level input?  If there is a built-in linestage, when you say the max gain is 59db (an odd number for a manufacturer to state), I assume you refer to total gain, phono stage plus linestage.  Yes? 

Once I get the facts straight, I can try to help.  We also need to know what amplifier and speakers you are using, and if possible the input sensitivity of the amplifier. (Defined as the magnitude of the input signal voltage required to drive the amplifier to its full output.)  But for now, if you are asking about the wisdom of driving another separate linestage with the output from the linestage already built into the Schiit, the answer is "not a good idea".

By the way, what is so terrible about a 70db S/N ratio?  For vinyl, that shouldn't be too obtrusive.
yes, my speakers are very inefficient Vandersteen Model 2C's from the late 80s. They need loads of juice to really make them rock. I just updated my Pre-amp to a Schiit Saga this past week, which is actually pretty awesome preamp (waaay better soundstage than the Onkyo receiver I was using as a pre before.) But the Onkyo had loads of gain, saga does not as it turns out.
My digital front end has no issues since my DAC has a built-in headphone amp (Audio-GD R2R-11) and can crank the knob and also set to high gain when needed. It's just the analog front end is a little light in the pants now.
By the way, what is so terrible about a 70db S/N ratio? For vinyl, that shouldn't be too obtrusive.

Mulv:  "Doesn't your Mani have a 48 dB setting?" I do believe you are correct, I may have missed that setting and gone straight from 42 dB up to the highest gain 59dB. The dip switch gain settings on the Mani are a bit of a pain in the ass to deal with. (but god bless it, it's a good phono). I will play with that tonight when I get home. 

Lewm: to answer the questions: Nagaoka  4.5mV output MP-150. Mani only has a turntable RCA input and a single output. Amp is a behringer Pro EP 2500, 450 watts/channel into 8 ohms. I have the gain all the way up on these all the time. Here are some of the Behringer specs:
Voltage gain: 34Db
Input sensitivity: V RMS (@8W)  1.23V (+4.0 dbu)
Input impedence: 10kohm unbalanced / 20Kohm balanced (I'm using unbalanced

Didn't seem like there could be anything wrong with driving it at max gain from the phono stage, just not totally sure. That's why I wanted some tips/cautions/gold nuggets if possible from you fine folks. I love this site!

here is my chain:

Nagoaka MP-150>Technics SL1200MKII>Schiit Mani>Schiit Saga>Behringer EP2500>Vandersteen 2C

Schiit saga replaced an Onkyo 805 receiver recently
Just about...and I mean this would only be when I can get the house to myself (which is rare unfortunately)...most of the time would be fine the way it is. I like the idea of having plenty of volume headroom (and I'm used to it, so it came as a bit of a shock)
As long as you can get it loud enough I don’t think there is any problem with your system. You are better off with the volume control in the higher range than the lower range. The only way to get headbanger volume is to replace those speakers with a speaker that is more sensitive. Other than that you will be spinnin’ your wheels! You will get used to the change.
I was actually looking at possibly replacing the Vandersteens with the Magnapan LRS, but just found out it's less efficient than the Vandersteens! (LRS is 86bd, Vandersteen 2C is 88db) I know that is not a headbanger speaker, but was still hoping to play that one loud, as well.
my speakers are very inefficient Vandersteen Model 2C’s from the late 80s.

As far as i know Vandersteen Model 2C speakers sensitivity is just 88dB, this is the reason why you need gain and powerful amp.

The reason why i love High Efficient speakers (97-101db) as the opposite to the average 86-88db, is the low power amp that can drive them easily, my preamp is passive/active. But i never use active mode.

If you want to solve the problem forever you may need to look for some high efficient speakers like Zu Audio or Tannoy ? It can be a revolution in your setup (if you haven’t tried some of them yet).

As for the cartrige with higher output you can try some with 5mV or even 9mV. Maybe you can borrow a $60 Shure M-44-7 (9mV output) to check your system with it.
Sell those Vandys and get a pair of Klipsch Heresy's! For ROCK they get the job done!
Well, the Vandy's are on the 4th decade now. I love them, but they are old. Not sure what shape those old drivers are actually in. It may be time to put them out to pasture. My problem is that the speakers I want are too expensive (Vandersteen Treo $8400) That's why I was excited when I saw all the good press that the LRS was getting - and only $650) I was looking at the the Tekton DIs, but that one still may be a bit too much at 3K) although those are extremely efficient, dynamic and full range (Need my Dynamics!). but too ugly for WAF (although the Vandy model 2s not exactly known for their good looks either). Probably have more research to do for speakers for around 1k that are efficient and Dynamic
For a few years, I wrestled with not enough SPLs, from my actively bi-amped system. Everything sounded great. No desire to replace anything upsteam. Just not enough volume to dispel the disbelief/take me there. It came down to swapping my(heavily modded) tubed main amps for SS, or- more efficient speakers than my new Maggie 1.7i’s. A pair of Emerald Physics speakers, brought it all together, wonderfully. Prices(new) start around $1400 a pair(I think, in their cheapest finish, factory direct, without their bass-booster).
@bstatmeister if you’re in USA you have to look for Zu Audio speakers, they will give you a try, full refund quaranteed and i believe they cover shipping both way within the USA (nothing to lose if if you’re not buying them). The best modern Full Range (crossoverless) speakers with paper cone drivers 101db ! I would recommend Druid line.

I’ve heard Klipsch Heresy III and Zu Audio will put them in a shame.
That Nagaoka MP-150 cartridge already is pretty high output at 4.5 mV so probably not much to to be gained on shooting for even higher.  I realize you love this cart anyway.  
You could also look into the Omega loudspeakers, very efficient, look great, sound better, & Louis is a great guy to deal with. 
Have you had your hearing checked recently?  ..not trying to be nasty...just seems you should have enough gain.
Pretty sure my hearing is fine. (Although my kids screaming in my ear everyday probably doesn't help.)

Not to rain on your parade, but for most music, and certainly the Rock it sounds like you may favor, the Magnepan LRS will absolutely require a sub or four. And if it’s a "dynamic" sound you’re looking for, though Maggies have their charms (I own a pair), dynamics is not one of them.

The suggestion of a more sensitive/efficient loudspeaker seems appropriate, and such speakers often also produce a dynamic sound quality. The sound systems at most concert venues use horn midrange and tweeter drivers, so we are used to hearing live music created with their sound character. Rock music-only listeners are often delighted with horn-type hi-fi speakers, which are VERY sensitive/efficient. HSU produces a very inexpensive speaker with a cone woofer and horn midrange/tweeter driver, if you want to try one on the cheap.

After looking over the specs and descriptions of the equipment, it appears to me that the root cause of the problem is that the Saga does not provide any gain, even when it is used in its active mode. (Or putting it more technically, its gain is 0 db). And the fact that the power amp is being driven with unbalanced signals, even though it only provides balanced inputs (its 1/4 inch TRS inputs are balanced, as are its XLR inputs), is most likely costing you 6 db on top of that. (The spec that is provided for unbalanced input impedance probably misleadingly refers to the impedance per leg of its balanced inputs).

If the good suggestion that was made of trying the 48 db gain setting of the phono stage does not prove to be satisfactory, rather than band-aiding the problem with a device providing additional gain I would consider fixing the root cause of the problem, by replacing the preamp with something else.

BTW, for everyone’s information the reference to "8W" in the power amp’s sensitivity spec ("1.23 VRMS @ 8W") is undoubtedly someone’s mis-translation of "8 Ω." Based on the specified gain of 34 db, an input of 1.23 volts will drive the amp to slightly more than its rated maximum power (450 watts into 8 ohms). If an input of 1.23 volts would only drive the amp to an output of 8 watts, more than 9 volts would be needed to drive it to full power, which would be ridiculous. And the gain spec would be wrong as well.

Good luck. Regards,

-- Al

I have a mani and  mp 110(same specified output) 48db is the setting you want. 59db does actually overload the mani. On my rig the 48db setting  closely matches the output from my cd player not quite equal, but close enough for me. Give it a try, I think you'll be satisfied. 

        Happy listening!
In my opinion we are trying to out a square peg through a round hole. I would recommend a system turnover which my require obtaining some used equipment here or on the other well known sites to get you speakers and a system that can do the job you want.
You mentioned your dream speakers were Vandys at $8400. For a fraction of that price you can get the Magnepan LRS which I heard At AXPONA and are a flat out deal at $650 or the .7i or 1.7i (which I own). If you get the .7i or 1.7i, then for less than $600 you can get the MyeStands which will improve dynamics and bass. I used to use a sub with my Maggies. Since the MyeStands, I am selling my subs. For the LRS you may need a sub. Get a small sealed sub. REL or Rythmikaudio. As for an amp, get a used solid state relatively high watt class AB or low watt high bandwidth class A stereo or integrated amp. For Maggies, I prefer the former. If you go with a higher sensitivity box speaker you can go with either. What ever is cheapest but good. That is where the most money is going to go. You may be able to keep the Mani and Saga. But those will be the weak links in your system. Sell the Behringer and Vandys. Yes it’s a partial system overhaul. Welcome to audiophile land!
Listen to @almarg . Try a new preamp. You could also buy a second power amp and run them as bridge mode monos.
The maximum output on the Saga is 10 volts. Can you please explain what that means as far as driving a power amp?
Thanks much
More about Zu Audio (a very high efficient crossoverless speakers).  
The prices and their trial policy is incredibly good for what you can get. 
These speaker can be driven with 5w amp in the big room. 
Life is so much easier with 101bd sensitivity speakers. 
@yogiboy The ">10 volt" maximum output spec of the Saga means that it is capable of putting out more than 10 volts before it will clip, when its active mode is being used. (In passive mode there is presumably no practical limit to its maximum output voltage). The output voltage it will provide at any given time, though, **if its volume control is at max,** will equal the input voltage provided to it increased by its gain. And in this case the gain of 0 db means that the output voltage will equal the input voltage.

I’ve seen several instances here in the past in which very large preamp output voltage specs (e.g., 10 or 20 volts or so) have misled people into thinking that is what the preamp actually outputs, rather than representing maximum capability before clipping.

Looking at the specific numbers in this case, the 42 db gain setting that was originally used on the phono stage (which is typical of gain settings that are used with moving magnet cartridges) corresponds to a voltage multiplication of 126 times. When the cartridge is putting out the 4.5 mv it is rated to put out under the standard test conditions the 42 db gain setting will result in an input to the preamp (and an output from the preamp if its volume control is at max) of 126 x 4.5 mv = 0.567 volts. Since the power amp only provides balanced inputs, it will interpret 0.567 volts provided to it in single-ended form as 0.567/2 = 0.28 volts. That is less than 1/4th of the voltage required to drive the amp to full power, **and will only occur with the volume control set at max** if the cartridge is putting out 4.5 mv. (Although the peaks of some recordings can cause the cartridge to significantly exceed the 4.5 mv it is rated to provide under the standard test conditions).

The bottom line here, as I see it, is that phono stages are generally designed with the expectation that they will be used with line stages providing significant gain. And in this case the line stage provides the same gain as a passive preamp, namely none, which will result in exactly the issue the OP described with many and perhaps most cartridge/phono stage combinations. So IMO the root cause of the problem should be fixed, before other changes to the system are considered.  That said, though, it does seem possible that the 48 db setting of the phono stage could prove to be satisfactory.

@noromance Thanks for your comment.

Best regards,

-- Al


Just for my edification only

How did you know or calculate that at 42db gain you would get a voltage multiplication of 126?

That seems like a very useful calculation to know based off a known gain.

Thank you
IMO - With a combined total of $500 new for the phono pre and line pre, a high noise floor is the penalty.  Increasing sensitivity or gain will still expose it.  A higher output cartridge at those same listening levels would require less gain, lowering the noise floor.  

I'm sure there are online calculators that can be found which when either number is entered will provide the other number. But I do that calculation manually, using a hand-held scientific calculator.

As you may be aware the ratio of two voltages, expressed in db, is:

db = 20 x log(V1/V2)

where "log" is the base 10 logarithm.

So to convert in the opposite direction, from db to the corresponding voltage ratio, I divide the number of db by 20, and then raise the number 10 to "the power of" that result. (For example, 10 raised to the power of 2 = 10 squared = 10 x 10 = 100).

In this case:

42/20 = 2.1

10^2.1 = 126 (rounded off to three digits).

Best regards,

-- Al

As usual Al comes up with the goods!

Thank you, exactly what i asked for and gives me better understanding.
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Please, please, please (a little James Brown here) don’t put those Vandersteen Model 2C’s out to pasture! There may be a speaker recone kit made specifically for those babies. To save money you could buy the kits and do it yourself or have a speaker tech do it for you.

Go ahead and take the speaker covers off and you’ll know right away if the cones are ripped, dented or decomposing in anyway. This way is far less expensive than buying new speakers and if you did decide to put them out to pasture you could at least sell them as they have been rebuilt, and not just sitting in your old hi-fi tech closet that we all have. Hope this helps.
So after a bit of testing with the different gain settings on the Mani 48db is the best and can give me what I need at the highest volume levels when called for. I did try the 59db setting, but after trying a few records that are highly dynamic, such as Dire Straights Love over Gold, there was noticable distortion. Initially, I missed the 48db setting and went from 42db to 59db, so I'm glad you guys reminded of it. I think I'm good here at this point. I have a lot to think about regarding next pair of speakers. I might buy 2 pairs: a horn set for rocking out and the Magnapan LRS for when I want some finesse sound depending on my mood. Any one have a good recommendation for a horn speaker for around $600 that is great bang for the buck? Thanks again folks!
Ok yep, I see...
What about the Hsu HB-1 MK2 Horn vs Klipsch RP 600M Reference?
Anyone have any opinions on the 2? Dynamics/slam (but non fatiguing) is #1 priority for me with my "rock" speakers
A minor correction to something I said in the first of my posts dated 4-27-2019. When I said:

Since the power amp only provides balanced inputs, it will interpret 0.567 volts provided to it in single-ended form as 0.567/2 = 0.28 volts.
Usually the gains and sensitivities of balanced inputs of a power amp are specified based on the difference in voltage between the two signals on the XLR connector, rather than on the voltage of each of the two signals. And usually the output power that would occur in response to a single-ended 0.567 volt signal provided to a balanced input would be the same as if it were a balanced pair of signals having a difference of 0.567 volts (i.e., each signal being 0.28 volts). A look at a schematic I found for the particular amp adds confidence to that conclusion.

The rest of my post remains as stated, except that the reference to "less than 1/4th of the voltage required to drive the amp to full power ... with the volume control set at max" becomes "less than 1/2 ...." as a result of that correction.

-- Al
Don't dump the Vandersteens lightly - they are a classic speaker.  Check the surrounds on the bass drivers, though (that means desocking them) or just by ear to make sure they haven't deteriorated - I had to do them on my Vandie 4As a few years ago.  Or move up to a good used set of Vandersteen 3A (even the Sigs) given that you like the sound.  They are readily available used in good condition.

Don’t worry, I won’t. I may end up back with the Vandy’s if the others aren’t cutting it. I feel like I am on a speaker journey, however, and must see what else is out there...
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