Electro Harmonix 12AY7 Preamp Review
IntroductionThe Electro Harmonix 12AY7 is a high voltage class 'A' tube path microphone preamp. It's also one of the most anticipated pieces of home recording gear to be released in a long time. Numerous folks who had used prototypes of the unit wrote glowing reviews of it on various message boards. Some people hailed it as a new dawn in affordable but professional-sounding home recording gear, while others dismissed it as marketing fodder and message board hype at its worst. I, being a sucker for hype, decided to take the plunge and plunk down $189.95 to purchase one for myself. Is it a project studio panacea, or is it a glorified paperweight? That's for me to know and for you to discover as you read on.
Boxes, Manuals, and Knobs - Oh MyThe 12AY7 is built into a large stompbox case. It looks like it's a distortion box made for people with hyperactive pituitary glands. I'm sure that they did this to keep costs down, which turns out to be a recurring theme on this unit. It has an XLR input jack, a 1/4" TRS output jack, and an XLR output jack. There are two pots: one for input gain, and one for output gain. The output gain knob only works when you are using the 1/4" output jack. It has no effect on the signal when using XLR output. I would have loved a 1/4" HiZ input and an insert jack, but those were likely omitted to save space and money. There are switches for phantom power, a low cut filter, and phase reversal. Lastly, there are three LEDs: a blue one to signify that the unit is powered on, an orange one to indicate clipping, and a green one to indicate that phantom power is on.
My preamp came in a nice little wooden box. The box contained the preamp, power cord, an EHX catalog, sticker, and flimsy piece of paper with the "manual" printed on it. I would have gotten a warmer and fuzzier feeling if the instructions were printed on the same stock on which the catalog was printed. Again, it appears to be a cost-cutting measure. You can download the manual off of their website here, so it's not a big deal if your original copy disintegrates.
TestingWhen I first powered on the preamp, I connected it to a Digi001 with an XLR to TS cable. This immediately led to an annoying electrical hum, even before connecting a microphone to the input. So, I tried using an unbalanced 1/4" to 1/4" cable. This made the hum even worse. Fortunately, using either a balanced 1/4" to 1/4" or an XLR to 1/4" cable eliminated the hum. The manual states that you can use unbalanced cabling, but I personally did not find that to be the case. There are other users who have had hum problems with this preamp, so I do not believe that this was an isolated issue on mine.
The phantom power circuit has a slow-ramp time, eliminating the transient "pop" sound that you get when engaging most budget phantom power circuits. This is about as close to a frill as you'll get with this preamp, but it's certainly a worthwhile one.
For my first test, I tried recording an acoustic guitar using a Studio Projects B1: an inexpensive, but fairly neutral microphone. I played the same guitar part through the 12AY7, and Art Pro Channel, an M-Audio Tampa, and a Symetrix SX302. The 12AY7 was clearly the "warmest" sounding of the bunch and revealed a level of detail that I had never heard out of the B1. While the sound from the Symetrix preamp was clean but lifeless, the sound from the 12AY7 almost felt like it was in stereo; it sounded very "alive." It would easily be one of my first choices for an acoustic guitar track, along with the Tampa. The noise floor is a little more than I would prefer for quieter work, but it's palatable and not overly distracting.
Next, I tried the 12AY7 on electric guitar using a Beyer Soundstar MKII microphone on a Fender DeVille 4x10 amp. I positioned the mic on the edge of the top right speaker, about an inch from the grille. It sounded, for lack of a better word, *big* on clean and lightly overdriven sounds. It sounded so large that I didn't want to stop playing! However, once I cranked up the distortion, things started to get a little muddy and less usable through the 12AY7. I later tried the B1 on some heavily distorted sounds, but the results were similarly muddy. In both cases, the sound was much less muddy (and actually quite nice) when going through the Pro Channel.
This leads me to one minor complaint about the unit. The input gain pot exhibits odd behavior around 8:00 on the dial. At 7:59:59, it's not quite enough gain for recording a loud source. At 8:00:01, it's too much gain for a loud source. If you breathe on the pot the wrong way, it will veer over the line one way or the other. In addition, the pot is very noisy and scratchy in this gain range. It's fine once the knob is set, but getting it set is a hassle. Again, this gives me the feel that this unit is, well, cheap.
Lastly, I tested the 12AY7 on my voice using a Studio Project C3 mic in its cardiod pattern. Wow! While the C3 is usually a little too brittle and shrill on my voice, it sounded downright lovely when going through the 12AY7. It worked well for voice-overs as well. The sound in both cases was big, detailed and alive. I performed the same tests using an Audix i5 mic (not necessarily a vocal mic, but I had it handy) and the Beyer mic, but the results were not as earth-shattering. They sounded a bit muffled and muddy in comparison. However, even if it doesn't work well with any other vocal mic in the world, it's worth the price of admission for how well it pairs with the C3.
The VerdictSo, is the 12AY7 worth the money? In my opinion, it is. It's not perfect and it has its quirks, but it sounds good if not great on multiple sources using budget microphones. I assume that this was the ultimate goal of the designer(s), and I do believe that they have succeeded. It brings a real tube preamp sound within the reach of folks who could only otherwise afford starved-plate preamps.
- Sounds good on most sources, sounds fantastic on some
- Slow-ramp phantom power circuit
- Electrical hum with unbalanced cabling
- No 1/4" HiZ input or insert
- Moderate noise floor
- Scratchy input gain pot