Does EAR324 phono stage sound like tubes ?

Hi all, I recently acquired an EAR 324 myself, and think it sounds very fine, musically speaking. (My previous phonostage was a PSA GCPH -- obviously not in the same league price-wise, but I insist on mono and polarity switches in addition to externally adjustable loading and balanced output, so my choices are extremely limited.)

However, there is a disappointing level of hum when in MC mode (i.e., when the internal step-up transformers are engaged). It's not bothersome at the lowest-gain "40 ohm" transformer ratio, or at moderate listening volumes in general. But at the "15 ohm" and "4 ohm" high-gain settings, although it never interferes with the music, at higher listening volumes it does interfere with the silences.

This is a problem I've never had with my previous phonostages, or with the outboard Bob's CineMag SUT that I auditioned for a while with the GCPH. The hum vanishes when the 324 is in MM mode, with preamp volume increased to compensate for the lower gain. So I'm thinking the hum may be inherent to the 324's internal SUTs. I've tried many combinations of cords and cables, power conditioning or not, ground lift, different cartridges, sources other than my regular turntable, even installed it in my bedroom system as a double check (where it was less audible, due to its not being a full-range system), but can't make the hum drop to an acceptable residual level unless I insert shorting plugs into the MC inputs -- obviously not representative of normal operating conditions.

Any comments or questions would be welcome...

Hi Isanchez, thanks for your input. Your experience with hum sounds similar to mine.

I think this finding of hum could be somewhat system-dependent. Not that the 324 only has hum in certain systems (although it's possible that certain 324's have more noticeable hum than others, and cartridge output level will definitely play a part in what is heard at typical listening volumes). But I suspect that perhaps the hum can be more noticeable in higher-powered, multi-way, full-range system contexts than it might in some lower-powered systems using smaller 2-ways or single-driver speakers (dynamic or electrostatic). At least this is what I took from trying my 324 in my single-driver bedroom system: the hum didn't disappear -- in fact I doubt it even diminished. But it became much less noticeable, both because that system isn't as highly resolving or extended at the frequency extremes, and can't be played anywhere near as loud.

About your impression that the 324 adds some benign distortion, I haven't heard this as such. I do find that using the output transformer gain-attenuation switch set to -6dB or -12dB can usefully tweak the harmonic flavor, in the fatness vs. tautness of the bass, tonality of the mids and sharpness of the treble, dependent on choice of cart, which step-up tap is selected, and in combination with the partnering preamp. Noticing this made me wonder that the output transformer ratio setting could likely have an effect on output impedance (and possibly even somewhat on the reflected MC input impedance?).

I haven't heard the Einstein, but I suppose your take that the 324 sounds more like legacy tube gear could have something to do with the amount of coils and iron used in the 324: input and output transformers, with inductors in both the power supply and the amplifier circuit. The 324 does not sound rolled off at the frequency extremes to me or anything like that, but unsurprisingly it does sound most transparent and neutral when used in MM mode, skipping the step-up transformers, though not as forceful or dynamic with my medium-output MC cart.

The 324's MM facility would certainly seem to have more attention lavished on it than is usually the case with high priced MC-capable phonoamps. This leaves me the possibility of trying a good MM or MI cart, or using an outboard SUT -- disappointing as that may seem after purchasing the 324 with its onboard SUTs. (But if it sounds better...)

As far as characterizing the overall sound goes, given the inevitable big differences among partnering carts and turtable setups, other than saying that, hum aside, this is far and away the most accomplished phonostage I've personally owned (but that's not many), I'll just restrict my comments to the particular issue I'm having with it. Fortunately, my current medium-output MC cart normally works best at the lowest-gain "40 ohm" tap setting, where the hum isn't really a problem in practical terms. But it does rankle me not to be able to utilize the lower-impedance taps if I want without the hum increasing, and I'm reluctant to make archival recordings knowing the hum is there and audible during silences and between cuts if you crank it up.

I'm going to contact Dan Meinwald and see what he has to say, but if the problem does lie in the step-up transformers themselves, or their proximity to the 324's power supply, I don't imagine anything could really be done to fix this. Interestingly, I dug out the 2004 Art Dudley Stereophile review, and although the reviewer doesn't mention anything about hum, in his measurements section John Atkinson does mention a degree of 120Hz hum he couldn't eliminate by playing with the grounding. Furthermore, with the MC step-up taps at their lowest-gain "40 ohm" setting (the only one of the three MC-loading settings he reports on regarding noise), he measured about twice the drop-off in S/N ratio between A-weighted and unweighted figures for MC mode as he found in MM mode -- a differential (of around 6dB) I'm assuming has got to be mostly due to a corresponding increase of LF hum in MC mode, and that might well have worsened if he'd also taken S/N measurements at the "15 ohm" and "4 ohm" tap settings.

Hi Shoshis, assuming you're listening to MC mode in the "15 ohm" or "4 ohm" positions through a full-range system, then that sounds like you've probably got a quiet unit there, but I'll add that the hum, if you had any, wouldn't be most apparent through the tweeters -- that's primarily the random noisefloor, which is also quite low in my unit. The LF hum I have however can be very clearly detected, not only audibly, but by placing a fingertip on a woofer cone, where as a defined sinusoidal hum it feels very different from the lower random noisefloor shown in MM mode.

BTW, I noticed in Atkinson's comments in Stereophile he mentioned that he "did not find any interaction between the phono inputs". This doesn't seem to be the case with my unit however -- with a signal present at Input 1 and Input 2 unconnected, I can nevertheless hear the music faintly through the speakers when Input 2 is selected on the front panel. Conversely, when listening to Input 1 with MM mode selected at the rear panel, I can still hear some mild frequency response modification when changing SUT impedance taps at the front panel -- which correlates with the fact that the rotary-control switching transients can also still be heard, so clearly the SUTs aren't totally removed from the circuit by the rear-panel switch.

Also, when I turn my 324 off, after a slight delay I get a dying-quail high-frequency tone though the loudspeakers that lasts for a second or two, at a volume high enough that, if I don't mute or turn down my preamp first, would give me cause for concern for my tweeters. Anybody else notice this?