Phono amp gain too high? (EAR 834p)

Excellent question! I dealt with this issue recently, but from a different angle. My concern was the amount of gain inherent in the mm section of a phono amp, rather than the amount of signal it presents to the following line stage. The reason for that concern is, the higher the gain, the lower the overload margin, generally speaking. A cartridge with as high an output as yours does not need as much gain as the EAR (and most other phono amps these days, optimized as they are for low-output cartridges) provides, and that high gain reduces it’s overload margin. I also use a high output cartridge (5 mV), so I looked around for a phono amp with a lower amount of gain, thereby increasing my chances of getting one with a higher overload margin. I found that in the Herron VTPH-1mm, which offers 42dB of gain, and a pretty healthy overload margin characteristic. It’s a discontinued product, but Keith had an mc version of the VTPH-1 in shop, and reconfigured it for me. Give him a call!

Hi Scott,

Yes, an excellent question, and as usual an excellent response by Bdp24.

I couldn’t find relevant specs on the LFD LE V either. I note, btw, that while the Clearaudio site indicates the cartridge’s rated output is 3.6 mv as you mentioned, at NeedleDoctor.com it is stated to have a 4.2 mv rating, both ratings based on standard test conditions of 5 cm/sec & 1 kHz. Not a big difference, in any case.

FWIW, 49.2 db is a voltage gain of 288x (i.e., 20 x logarithm 288/1 = 49.2), so 4.2 mv would be stepped up by the 834P to 288 x 4.2mv = 1.21 volts. Some recordings having particularly high volume dynamic peaks may cause the cartridge’s output to exceed its rating under standard test canditions by several times, to perhaps 5 or 6 volts or so. That may be helpful to know if you can eventually find specs on the LFD.

While the caution Bdp expressed about the overload margin of a phono stage that provides more gain than is usually provided for a given cartridge is one that should always be considered in such cases, looking at the overload points indicated in Stereophile’s measurements of the EAR 834P I don’t think that would be a problem in this particular situation.

As you realize, though, without further information about the LFD integrated amp we can’t say anything with certainty about the possibility that it may be overloaded. If its volume control precedes any of the gain circuitry in its signal path, as is the case in many designs (but certainly not all), that won’t be a problem. But even in that event there could still be a problem of having to operate the volume control too low in its range to be desirable, depending on the gains and sensitivities of everything that follows, including the speakers, and on the characteristics of the volume control at low settings.

My guess, fwiw, is that the odds are **somewhat** in favor of neither of those issues being a problem. However, in addition to significant uncertainty in that regard I’ll mention that many reports I have seen of the support and service EAR tends to provide are suggestive of it being, um, not in the same league as that by provided by Keith Herron, who is an absolute treasure to deal with, as well as being someone whose designs receive virtually unanimous acclaim. I would therefore take Bdp’s suggestion to heart. Or better yet, if $3650 might not be a show-stopper consider a new VTPH-2.

Good luck. Best regards,
-- Al

And his usual great advice from Al! I haven't heard anything about it's sound quality, but Mike Moffat (Theta designer) offers a phono amp with only 30dB of gain, the Schitt Mani. It'll cost you only $129 to give it a try.

Thanks so much for the input, gentlemen.  I have heard nothing but fantastic reports on the Herron, but it's a bit out of my price range.  The EAR comes up here used reasonably often, and I'd always wanted to try it.  Actually, right now I have the problem of needing just a little more gain.  I'm using the LFD LE/SE phono stage (39db for mm) and with the Maestro V2 (I think the V1 was 4.2mV and the V2 is 3.6mV) I get enough gain for a decent listening level, but not for anything more than that.  The EAR might actually be a good fit.  I'll have to do some more investigating...

Thanks again for the input,Scott

That's great to know!  I was looking at the older model - I'll get in touch with Mr. Herron to see if he has any others that have been traded in.  He sounds like a true audiophile and not a salesman.  Good to hear!

I second and third the above endorsements of Keith Herron's wonderful phonostages.  I have the VPPH-2 and couldn't be happier.  Keith indeed is great to work with and often has used/demos available.  Also here is a link to used sold listings on Hifishark http://www.hifishark.com/search?q=herron+vtph.
I hope we're not pushing too hard.  By the way, no relationship to Herron, just a satisfied customer.

Thanks, Abnerjack.  Good to get confirmation on Keith's gear.  Will look into it shortly...

By the way, most of the difference between the VTPH-1mc and the -2 is in the mc section, which was significantly revised and improved in the -2 version. The difference between the -1mm and -2 when using a mm cartridge should be minimal.

Scott,
FYI, My friend had an EAR and it had a volume control to lower the gain. He had it plugged into his power amp without using a preamp. He was using a 5mv cartridge and it sounded great ! If you buy one used make sure it has a variable volume,as some of them do not.

yogiboy  " ... If you buy one used make sure it has a variable volume,as some of them do not."

A volume control on a phono preamp? That doesn't sound like a good idea - it's likely to lower the system's s/n ratio. It's better to properly match a phono preamp to the line stage so that the line stage can't be overloaded. Then, adjust volume from the linestage.

cleeds, Here it is !
http://www.needledoctor.com/EAR-834P-Black-MM-MC-Phono-Preamp?sc=2&category=401

Unless I’m mistaken (a real possibility), the setting of the volume control does not infact determine the gain of the amp, but instead attenuates the phono amp’s full output---not the same thing of course. I believe the gain of the amp is set, the full output of the circuit is sent to the volume control, which attenuates it to varying degrees depending on where it is set. The volume control doesn’t decrease the gain of the circuit, only attenuates the full output of the amp. A look at the schematic will provide the answer---look for where in the circuit the volume control is located; if it’s before the amplification is achieved, then yes, it may lower the gain of the amp. But I doubt it that’s where it is. If it was, EAR’s published specs for the amp would show variable gain. The variable output would provide a solution to the problem of the phono amp overloading the line stage, however.

Thanks for all the information.  The specs provided on the Needle Doctor website show the following:

EAR 834P Specifications:
Input sensitivity for 1 volt out @ 1kHz:
MM 2.2mV - MC 0.22mV
Max output 30V
Noise (unweighted) -80 dB (1HF)
Tubes ECC83 x 3

Does this suggest that 2.2mV is the upper end of the range for a moving magnet cart?  Not sure I fully understand the above specs and how they would interact with a given preamp or integrated amp. 

Thanks for any clarification you can provide,Scott

Hi Scott,

No, it just means that 2.2 mv in (in MM mode) will result in 1 volt out, at 1 kHz. Based on those specs, the maximum input the phono stage could process without clipping, in MM mode and at 1 kHz, would be:

(30 volts/1 volt) x (2.2 mv) = 66 mv.

Obviously that represents a goodly margin relative to the maximum input any MM cartridge is likely to provide, and corresponds closely to Stereophile’s measured 1 kHz overload point of 69.2 mv.

The gain of the phono stage in MM mode, per those specs and expressed as a ratio, is:

(1 volt)/(0.0022 volts) = 454.5, meaning that the output voltage will be 454.5 times as great as the input, at 1 kHz, as long as the clipping point is not exceeded.

Expressing that gain in db:

20 x logarithm (1/0.0022) = 53.2 db.

As you’ll realize, that is about 4 db higher than what Stereophile measured. So either the spec is not quite accurate, or the design changed somewhere along the way, resulting in differences in gain among 834P’s that were manufactured at different times.

In the interests of simplicity I’ve neglected RIAA equalization in all of this, which does not affect 1 kHz but which compensates for a progressive increase in frequency response at higher frequencies and a progressive decrease in frequency response at lower frequencies that is introduced in the record-making process. See the first figure in this Wikipedia writeup.

Best regards,
-- Al

Al,  Thanks for all your help and valuable insight.  Some of it goes over my head as I haven't taken a math class in 30 years.  I just came across a phono amp that has the following as one of it's specs:

sensitivity 2 mV for 0.5 V rms o/p

What does that mean in terms of gain?  Sorry, I was a Spanish major to avoid taking math classes in college :)

Scott

Hi Scott,

"o/p" presumably means "output."  If 2 mv in results in 0.5 V out, since 0.5 V = 500 mv the gain is 500/2 = 250x (i.e., 250 times).

The ratio of two voltages expressed in db equals 20 times the logarithm of the ratio.  So 250x is a gain of:

20 x log(250) = 48 db

Best regards,
-- Al
 

Gracias :)

If I may resurrect this thread a year later...

I am having some cartridge/EAR mis-match issues of my own.  First of all I have an EAR 834p and it has worked wonderfully with my low output Grado Reference cartridge (.5mV).  Since I've had the Grado for nearly 15 years I decided it was time to get a new cartridge so I sent it back to Grado in exchange for there current version of the same exact cartridge. This seemed like a safe move.  One of the differences between the older version of this low output cartridge and the newer is that they increased the output from .5mV to 1mV.  I had no idea how much difference this would make if any at all.  Well it now seems that playing the new cartridge using the MC setting on the EAR results in too much gain.  I get distortion, particularly on highly modulated musical peaks on many records.  Even if I turn down the volume on my line stage to almost it's lowest setting it is still very "hot" and the distortion frequent.  When I change the setting on the EAR to MM I then have to turn the volume way up on my line stage and it just doesn't sound as lively or dynamic as my old cart.  So, after talking to Grado support it seems I am caught in the middle where the output of the cartridge is too high for MC and too low for MM.  Grado suggested that I switch to their high output version of the same cart (4.8mV)...I am considering that but am also considering abandoning the Grado and move to a true low output cartridge like the Dynavector XX2 for instance (.28mV).  Seems I am having to move either up or down.  Any suggestions or ideas how I can get my new cart and EAR 834p to work better together?

@randyhat
You can lower the gain of the EAR if you relpace the 12ax7 with 5751 tubes. The 5751 has 30% less gain than the 12ax7. I had the same problem (too much gain) with my Quicksilver phono and the 5751 did the trick!

Thanks for the suggestion.  I need new tubes anyway so I may just try that.  Think it would be best to replace all 3 with 5751s?

@randyhat
If the EAR has a separate gain tube then that is the only one you would need to replace. If not you can replace the 3 tubes with 5751’s. My phono has a gain tube so I only replaced that one tube to lower the gain. Here is the info about a 5751 tube!
https://www.tubedepot.com/products/jj-5751-preamp-tube

Second yogiboy's suggestion.  I have a trio of nos GE triple mica 5751's that I rotate in my modified (Singerman) 834P and can verify that they do noticeably reduced gain although I sometimes use them because I like their sound in the preamp not because I need to reduce the gain.  Not terribly expensive and I found them to be pretty available a couple of years ago.  

Frank Van Alstine used 5751's in his redesign of the Dynaco PAS 3, preferring it's gain structure, low noise, and distortion characteristics to the stock PAS' 12AX7.

As do about 3/4 of people with long tube experience .
Main reason I bought tube pre with gain nob, hit that sweet spot for 5751's.

In case anyone is still replying to this thread, everyone here knows more than I do about gain issues in analog! I have a koetsu black on its way (output .45 or .5 measured, people claim) and currently run a Denon ha-500 head amp with 24 or 36 dB switchable gain going into an EAR 834p mm only, without volume control. I run it at 24 dB. Should I be worried about the gain overloading my Thor ta-1000 linestage preamp? Certainly I wish the volume control of Thor could get past 10 o'clock but with cartridges in this output range it won't. But the volume control position is a small concern compared to an "overload" risk, which I don't really understand.

Thanks for any thoughts.

Montaldo, you do have a lot of gain in the signal path you’ve described, for a 0.45 or 0.5 mv cartridge, assuming the gain of your version of the 834P corresponds to the 49.2 db which Stereophile measured for the MM section of the MM/MC version they reviewed. But **if** the volume control in your Thor line stage precedes any active circuitry in its internal signal path, as is the case in many designs, you won’t overload it. If there is active circuitry "ahead" of its volume control, though, it may or may not be overloaded; I couldn’t find enough information on it to be able to predict that either way.

Since the cartridge is already on its way, I would suggest that you simply listen for signs of distortion on high volume musical peaks. If distortion on high volume musical peaks is evident even when listening at low overall volume levels, it would signify that there is an overload problem. In which case the suggestion that was made earlier of changing tube types in the 834P may be a solution.

Also, as you alluded to the combination of a 0.45 or 0.5 mv cartridge, 24 db headamp gain, 49.2 db phono stage gain, and the 20 db gain which the Thor line stage apparently provides, could very well result in your having to use the volume control at undesirably low settings, depending on the gain of your power amp and the sensitivity of your speakers. If that turns out to be a problem, though, a Rothwell passive attenuator inserted at the input of the power amp may be a good solution.

Regards,
-- Al

P.S: When I said ...

If distortion on high volume musical peaks is evident even when listening at low overall volume levels, it would signify that there is an overload problem.

... I’m assuming of course that cartridge mistracking is not the cause.

Regards,
-- Al