Phono amp gain too high? (EAR 834p)
I have long been interested in trying the EAR 834P, and I recently came across the old Stereophile review of it. In the measurements section, the gain for MM carts was 49.2db and 68.2 for MC. That seems to be an inordinately high gain if I'm not mistaken. I don't know how to determine whether this would overload my integrated amp. I am running an LFD LE V and a Clearaudio Maestro V2 (3.6mV). I can't find specs on the integrated as far as gain and input sensitivity. As I understand it, there is no active preamp in the LFD, but I can't even confirm that. Is there someone with better technical understanding who can help?
Thanks for your thoughts,Scott
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- 29 posts total
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 |
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 |
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