Electro-Harmonix 12AY7 Mic Preamp?

[matta]

I know this pre is old news for many, but does anyone own one or has checked it out?

It seems a step up from most 'tube' budget boxes running on starved voltages of 48V, as this seems to run on 200V, not bad for an under $200 box.

Here is the promo blurb

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12AY7 Mic Preamp

In today?s market, most affordable tube preamps for microphones are disappointing. Electro-Harmonix has changed that with the creation of the 12AY7 Mic Preamp. Equipped with a 12AY7 EH tube and a 12AU7 EH driver, it gives microphones the widest dynamic swing with the warmest possible tone and accuracy. It uses an actual 200-volt supply instead of the "faked out" 12 or 48 volts you?d get with common models, delivering 50 dbs of gain into a high impedance load, and about 40 dbs of gain into 600 ohms. The 12AY7 Mic Preamp?s special FET current-balancing circuit allows the tubes to amplify the microphone signal to line level while eliminating noise, and protecting against hum and hostile electrical environments. It has an extra TRS output for separate line control, which can be used as a splitter or an AUX Send for monitoring. Input connections are balanced In and Out (XLR) with a ¼" TRS balanced buffer out. The unit also boasts a phase reverse switch and a +4dBm indicator light for setting optimal mic level. The 48 volt phantom power is soft starting and "pop free."


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Would love to hear what users think, maybe even some inside photos.

Cheers

Matt

 

[rodabod]

Hey Matt,

Are you back in SA? I probably should have given you a shout when you were in Scotland / the UK - didn't know at the time though.

Anyway, back to the point. The designer of this box has discussed it and its design over at the tape-op forum. He mentions changing tube types and adding input transformers for more gain.

When he suggested adding a 1:10 transformer to the input, I asked if this would lower the input impedance too much, but I'm not sure if he understood my question....

http://messageboard.tapeop.com/viewtopic.php?t=29210&highlight=12ay7

 

[matta]

Hey Rod,

Yeah I got back a week ago today. I had wanted to get in touch when in Scotland, but I was only in Edinburgh for a VERY quick day, just before Hogmanay (SP) stayed in the Ramada on Princess Street, what a city! I hope to go back in the future. The other 3 days were spent up on the Kinnard Estate 2 hours north of Edinburgh, 7 inchs of snow and snowed in, love every minute!

Thanks for the heads up on the Tape Op thread, I'll make my way over there now.

Cheers

Matt

 

[Godders]

I own one of these, I really like it but I don't have experience of high end boutique pres so my opinion probably isn't that useful. It's certainly a step up from all the other prosumer junk I've used. It's fussy about what you hook it up to though, you get a nasty hum out of the pre going to an unbalanced in.

Here are some pics:

Those EH boys like to put funny messages on their pcbs:

:green:

I know the threads a bit old but I hope that's of some interest anyway.

Cheers

Nick

 

[Kev]

I'm interested.

are we sure it has a real HT ?

It's fussy about what you hook it up to though, you get a nasty hum out of the pre going to an unbalanced in.

I'd like to know more about this
and to find the cause
and then a simple solution

Ultimately a circuit or a good approximation of the circuit will be needed.

 

[rodabod]

[quote author="Kev"]I'm interested.

are we sure it has a real HT ?
[/quote]

I think it is.

Did you read the designer's response as I suggested above? Not sure if he mentions it there?

http://messageboard.tapeop.com/viewtopic.php?t=29210&highlight=12ay7

Sounds cools to me. I may get one. What more could you want for the money?

It is supposed to sound good despite lacking gain and requiring a balanced load.

 

[AMZ-FX]

I have one of those power trannys... it is driven by a 12v AC wallwart and then steps it up to 150v -160v for plate power. I don't think it makes 200v but I could be wrong.

I wonder if the heaters are being driven directly by the 12v AC and that is part of the problem?

regards, Jack

 

[mhelin]

What, no mic input xformer? Is this actually a FET pre (2x 2SK117)?

 

[Gus]

I could be a voltage doubler I do that for some tube microphone power supplies I built for myself

 

[rodabod]

Bump.

I've just bought one of these. At £49 secondhand I couldn't say no.

Seems pretty good, and fairly quirky (like all EH stuff....)

It only has ~50dB gain, although was considering adding a 1:2 at the front for an extra 6dB gain for quiet situations.

It's funny having a "real" tube preamp but without the iron. I'll report back once I get to use it properly.