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!
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,
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
Having no need for the extra gain of the VTPH-2 (which has switchable mm/mc sections), and not wanting to have to pay for it anyway, I gave Herron a call to see if he knew where I could find a -1mm model (it was discontinued and replaced by the -2 over a decade ago). Keith informed me he just happened to have a traded-in (he does direct sales, I believe) -1mc, and that he could convert it into a -1mm for me. Sold!
Keith reconfigured the amp, put in new tubes (even switching two of the 12AX7's to 12AT7's, for a gain reduction of 2dB---from 44 to 42, and sent along the AX's in case I in the future wanted the 2dB back!), burned it in, and gave it a complete checkout. All for $1225! You could give him a call and see if he has another.
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.
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.
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.
I ran into a similar issue when trying to find a phono preamp to go with my Naim gear. Although the input overload margin was high for my Naim preamp I was finding anything greater than 60dB gain seemed too "hot" and the sound suffered. I could never get a good reason for this either from Naim or Klyne. Both pointed fingers. But ultimately I figured that since Naim amp/preamps have considerable gain overall that finding something similar in gain to what Naim phono boards were generating was the way to go.
Then there's the opposite when I was using a MM cartridge with a AI M3A and a CJ MV60SE. Even though the MM had a really high output, 6.5 mV, and the M3A's MM boards had 28dB and a total of 58dB of gain the cartridge seemed overly anemic in bass. When I added a sep. phono preamp and went to 50dB of gain did it seem to sound correct. Ans then there' my friend who had a M3A with differing amps and a ClearAudio MM cart. (3 mV) and had no issues. Go figure.
Unfortunately, you really don't know about interactions until you try them. I too wanted to try an EAR 834P. I've only heard one once (Vol. pot ver.) with an MC directly to an amp. The vol. pot was really touchy and probably defective but the sound was awesome, at least for classical music.
If you are not willing to take a chance then go for a unit that has adjustable gain settings.
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
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.
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 :)