Phono amp compatibility with integrated

Cartridge output -> phono-stage sensitivity ->phono-stage gain->phono-stage output voltage -> input sensitivity of integrated amp...
All these parameters should be measured in RMS in order to define 'sweet spot' of synergy between components or have fully adjustable phono-stage like Violectric PPA600. Adjustable means you win and win again.

Thanks for the response.  However, I don't know what type of "sweet spot" I'm shooting for.  For example, I'm looking at the Lehmann Black Cube SE II, and it lists the following specs:

Sensitivity for output level 775 mV/ 0 dB (with activated high gain switch):  MM: 3.8 mV/1 kHz; MC: 0.38 mV/1 kHz

Gain 1 kHz:  MM: 46 dB; MC: 66 dB

Maximum input level 1 kHz:  MM: 45 mV; MC: 4,5 mV

Signal to noise ratio (RMS unweighted):  MM: 71 dB; MC: 63 dB

Output impedance:  47 ohms

So, what am I looking at here to see if it will work well with the Naim's sensitivity?  Sorry, I'm a newbie at the analog thing, so some things that seem obvious may not be clear to me.

Thanks again,Scott

Scott you should also research the input capabilities in terms of maximum and minimum voltage applied to the input. Some preamplification units may even blow either input or output stages when overloaded. The wider range, the better equipment quality. In my case I use 2.2 mV HOMC cartridge into 60dB phonostage gain fed to preamp with sensitivity 300mV and maximum input range of 12V. I consider these parameters great for large dynamic headroom. It allows me to listen to any type of demanding classical music where I have to hear clearly quiet and loud parts. I don't look much at S/N ratio. I don't have adjustable phono-stage. There's only MM/MC switch, but my preamp is capable of handling low and large input voltages. In fact it actually benefits when input voltage is sufficient or large. 

Hi Scott,

The Vincent phono stage has specified gains of 40 & 60 db in MM and MC modes, respectively. Those are fairly typical numbers for phono stages, and will work well in most systems with the majority of cartridges (MCs having extremely low outputs being the most likely exception).

40 and 60 db, btw, correspond to voltage gains of 100 and 1000 times, respectively, based on the relation db = 20 x logarithm(Vout/Vin).

So the 1.6 mv output of your DL-110 cartridge (under the standard test conditions) is boosted by the Vincent (in MM mode) to 160 mv. Very high volume dynamic peaks on some recordings can sometimes exceed the standard test conditions by a factor of several times, so under those extreme conditions the Vincent may input several hundred millivolts to the Naim integrated amp, which **with its volume control at max** will be driven to its maximum rated output power by an input of 150 mv.

If too great an input is supplied to the amp, the consequences can be:

1)Overloading and distortion, as you’ve found, especially if the design is such that active circuitry precedes the volume control in the amp’s internal signal path.

2)Having to operate the volume control undesirably close to the bottom of its range. That tends to occur most often with digital sources (which commonly have maximum outputs of 2 volts or more), but can also occur with some phono stage/cartridge combinations.

The Jolida JD9 Mk2 has much higher than average gains for its "high" outputs, 60 db MM and either 75 or 85 db MC, which (if I am correct in assuming the gains cannot be reduced via internal settings) are way too much for your particularly sensitive integrated amp.

The higher voltage output of the Heed also provides too much gain for your purposes, 50 db MM or a choice of 62, 71, or 78 db MC. The gains of the lower voltage output are about 11 db less than those figures, which would be reasonable for your purposes except that for unknown reasons you’ve found the sonics of that output to be disappointing.

The Lehmann apparently provides selectable gains of 46 or 36 db MM, and 66 or 56 db MC. Again, the higher gain settings are too high for your purposes, probably even with the 0.25 mv DL-103r that you’ve tried but have had issues with. The lower gain settings should be suitable. I have no knowledge of the sonics of that phono stage in either setting, however.

In general, IMO a reasonable goal would be for the phono stage to boost the specified output of a cartridge to a level that is greater than the input sensitivity number of an integrated amp, but not a great deal more. But a precise universally applicable guideline can’t be defined, as amplifier power, speaker sensitivity, the location of the volume control in the amp’s internal signal path, other design factors affecting overload margins, preferred listening volume, the dynamic range of the music, and other variables all conspire to muddle the issue.

Best regards,
-- Al

Thanks for mentioning that phono stage, Steve (Williewonka). Looks like its unbalanced outputs provide a MM gain of 40 db, and a MC gain that is selectable between 54, 60, and 66 db, with several selections also being provided for input resistance and input capacitance.

As far as gains and loading are concerned, that all seems ideal for use between the Naim integrated and the great majority of phono cartridges, including Scott’s two Denons, his 0.5 mv Grado, and probably also his 5 mv Grado (he referred to the Grados in other recent threads). It might be somewhat marginal on some recordings with the 5 mv cartridge, however, although Scott had reported in another thread that the Vincent phono stage, which also provides 40 db gain in MM mode, worked well with that cartridge and the Naim’s 150 mv sensitivity.

Best regards,
-- Al

This is a very edifying discussion - thanks everyone. So, if I’m understanding correctly, the high sensitivity of the Naim 5i-2 means that some of the higher output MM carts (closer to 5.0 mV) will overload the integrated when run through a phono amp with a standard 40 db of gain for MM carts. If I’m sticking with the Naim, it sounds like a HOMC (or a LOMC with the appropriate gain options in the phono amp) will be the best bets. Am I in the ballpark? Would a lower-senstivity integrated or preamp give me more options with the phono carts?

Thanks, Scott

Scott, yes, calculations suggest that overloading MIGHT occur on some recordings having particularly high volume dynamic peaks, with the combination of a 5 mv cartridge, 40 db of gain, the 150 mv sensitivity of your integrated amp, and (apparently) the amp's design incorporating active circuitry ahead of the volume control.  Although as you indicated in your other recent thread, the 5 mv Grado worked well with the recordings you listened to when you used it in conjunction with the 40 db Vincent.

But you've preferred the sonics of the 1.6 mv DL-110 to the sonics of the Grado, and you are happy with the Naim.  And 40 db should be fine with that combo.

Best regards,
-- Al

Thanks so much again everyone.  I'm starting to get a handle on all the compatibility issues.  I'm considering trying a tubed phono stage again, as I generally prefer the sound of tubes somewhere in the system.  A couple of people, including Yogiboy above, recommended the Croft RIAA Phono, but I can't find specs for the gain.  Does anyone know the gain that the Croft provides?  

Thanks, Scott

Maybe this chart will help. You can also set all the gain switches to the off position. http://usr.audioasylum.com/images/3/32746/JD9_settings.jpg

... if I used the correct conversion, the Croft RIAA has about 48 dB of gain.

Yes, that’s correct. The spec is indicated as 500 mv out for 2 mv in, which corresponds to 48 dB of gain. Too much for use in conjunction with Scott’s integrated amp with a 5 mv cartridge, and on at least some recordings probably also too much for use with a 1.6 mv cartridge. And since the Croft RIAA is intended for use with MM cartridges, I would have concern that its noise performance would make it unsuitable for use with Scott’s 0.5 mv Grado, even if the amp provides enough additional gain to produce adequate volume.

The problem with phono cartridges and phono preamplifiers is that there aren’t standards for cartridge output and hence, no standards for gain stages in phono amplification.

As I understand it the problem is that there are TWO standards, one based on a CBS test record, and one on a JVC test record. As can be seen in the listing for the last band on each label, both are based on a velocity of 3.54 cm/sec at 45 degrees, but the JVC label does not indicate if that corresponds to the peak value or the rms value of the waveform, which results in a possible inconsistency of 3 dB. Also, some cartridge manufacturers refer to 5 cm/sec, without specifying peak or rms (5 cm/sec peak is 3.54 cm/sec rms), which results in another possible inconsistency of 3 dB.

So I would expect that cartridge output ratings provided by different manufacturers would generally be defined on a basis that is consistent within 3 dB, or at most by 6 dB.  Of course the outputs of different cartridges, when defined consistently, can vary widely, which is perhaps what you were alluding to. 

Best regards,
-- Al

Thank once again.  If I understand things correctly, it's really the high sensitivity of the Naim that is somewhat limiting in terms of carts and phono amps.  Even a standard 40db of gain would be pushing the limit with a higher output MM cart, correct?  The Vincent (with 40db for MM) does seem ok with the 5.0 mV Grado (I'm listening to it right now, and it sounds pretty good), although I haven't cranked it up.  Will have to wait until my upstairs neighbor leaves.  

I haven't come across too many phono stages that have gain settings below 40 db (the Black Cube is the only one), which leads me to believe that the Naim has an unusually high sensitivity.  In fact, I did a quick search on a couple of sites, and most integrateds are much lower sensitivity than the Naim.

Thanks again,
Scott

That's mostly correct, Scott.  But a couple of clarifications:

If I understand things correctly, it's really the high sensitivity of the Naim that is somewhat limiting in terms of carts and phono amps.

I would say that what is somewhat limiting is the combination of the high sensitivity of the Naim and the overload margin of whatever circuitry it has "ahead" of its volume control.  Some designs have essentially no circuitry ahead of the volume control, or circuitry that may have greater overload margins, in which case the issue would not occur even if their sensitivity is similarly high.  (Although in those cases the volume control may have to be operated undesirably close to the bottom of its range, depending on cartridge output and phono stage gain).

The Vincent (with 40db for MM) does seem ok with the 5.0 mV Grado (I'm listening to it right now, and it sounds pretty good), although I haven't cranked it up.  Will have to wait until my upstairs neighbor leaves. 

Cranking up the volume shouldn't make any difference with respect to this issue.  For a given listening volume, the settings of the volume control that are used with various phono stages would result in the same signal level being seen by everything downstream of the volume control, regardless of the gains of the phono stages.  Although it's possible that some forms of distortion may be more readily perceived at high listening levels than at lower levels.

Best regards,
-- Al
 

 

Al - thanks so much for taking all the time to explain things.  People like you make this site one of my favorites.  

Best, Scott

And, if you don't mind my asking yet another question...how would I know whether a particular integrated has additional circuitry that would affect the compatibility with an analog front end?  I like the Naim, but I'm always interested in trying something new/different.

Thanks, Scott

http://www.quicksilveraudio.com/products/phono.html
This is the phono preamp I use with my low output Grado’s. Take a look at the instruction manual. This one just might  do the trick for you!

... how would I know whether a particular integrated has additional circuitry that would affect the compatibility with an analog front end?

In situations involving high integrated amp sensitivity, and/or high phono stage gain, and/or cartridge output that is greater than is typically used with that amount of phono stage gain, in most cases it would probably be best to ask the manufacturer how much input voltage would overload the amp.  And then perform calculations along the lines of those I described in my first post in this thread, to estimate the upper limit of the input voltage the amp might see on recordings having dynamic peaks at particularly high volumes.  Or, alternatively, simply ask if the amp would be suitable for use with the specific front end components being considered.

And thanks for the nice words :-)

Best regards,
-- Al

Yogiboy - I've heard great things about Quicksilver products, and judging by some of your recommendations I believe we have similar tastes in audio gear.  However, if I understand things correctly, the 67 db of gain for the low output carts would be too much for the Naim.  I'd need to keep it down to around 60db or even less.  Maybe I should be shopping for a friendlier integrated rather than a phono amp...

Scott

Scott,The gain is 47 db for mm cartridges. It is 67 db when the QS SUT is used for low output moving coils!
Yogiboy

Ah, so you're saying that I could run the low output Grado through the MM stage...?

You sure can. I use that phono stage with my low output Grado's. You can give Mike a call at Quicksilver,he will answer any question you have!

I see.  However, then I couldn't use a higher output MM cart as the 47db of gain is too much.  Might even be a poor match for HOMC, too.  Damn this Naim...:)

The minimum is .5 mv. I use a 1.5 mv cartridge. You should really give Mike Sanders a call and explain your situation to him. I am sure he will answer any question you have with matching it with your Naim