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PreSonus XMAX vs Art ProChannel vs. EHX 12AY7 pre-amps.

I'm contemplating my next buy. It will be a preamp. I'm looking for "that tube sound". I need richness and clarity, etc. This preamp is primarily for vocals. If it does vocals well, then I'm happy. I can always try it out on other things.

That being said, I'm torn between these two:

[=""]ART Pro Channel Tube Mic Preamp: Shop Pro Audio & Other Musical Instruments | Musician's Friend[/]=""]ART Pro Channel Tube Mic Preamp: Shop Pro Audio & Other Musical Instruments | Musician's Friend[/]

[[url=http://="…"]Electro-Harmonix 12AY7 Tube Microphone Preamp: Shop Pro Audio & Other Musical Instruments | Musician's Friend[/]="…"]Electro-Harmonix 12AY7 Tube Microphone Preamp: Shop Pro Audio & Other Musical Instruments | Musician's Friend[/]

My current rig uses the PreSonus FP10 (formerly Firepod). I am happy with the transparent XMAX preamps it has, but I want something better for my vocals. My voice is getting strong enough (or "pro" enough) to warrant a dedicated preamp for it.

Any advice?


bigtree Thu, 10/06/2011 - 12:48

It does look very nice and will be much better than what you are using. The reviews on it are amazing. Plus, if Dave likes them, there must be good reason. Here's an interesting video from Bill Roberts Brady.

and ProAudioStar who has it hyped to the max!

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hueseph Mon, 11/21/2011 - 21:56

assemblethelight, post: 379233 wrote: From my research and also looking at the your budget, i would probably go a bit higher in price and get a Golden Age Pre-73. Why? Well, because if you do not like its stock sound, then you can def invest into modding it. They are $375

My bro just picked up the GAP73 a couple of weeks ago. He sent me some audio samples for me to blind listen compared to his old Mackie mixer. Needless to say there was no contest. The GAP73 is a sweet sounding preamp. It really has a way of toning down the highs. Of course this was an unfair comparison but I can tell you that you would be hard pressed to find a stock preamp in any of the mid range and probably some of the high end audio interfaces that could come close. For the price, it's an incredible bargain.

RemyRAD Fri, 10/07/2011 - 20:44

John, might I suggest a simple transformer for your current preamp? I think the Transformers are more relevant than the search for the tube sound. When the sound goes into that coil and goes round & round, it comes out at different frequencies, at different speeds. It's these phase variations from input to output That we have come to enjoy the sound of. Phase differences do not just exist between 2 different microphones or two different inputs, etc.. And it's these minute variations that make a distinctive difference in what we perceive. A UTC, Triad, Jensen, St. Ives by itself might just do the trick. Being microphone transformers however, they provide free amplification before it goes into your microphone preamp. If it's a ratio of 1:6 you get six DB of gain. 1:10, 10 DB of gain, 1:15, 15 DB of free application. No strings attached. Call now! Operators standing by! Generally you will find that most tube equipment has an input transformer to begin with. Wonderful transistor preamps like API, NEVE, all use transformers and all have that warm quality that everybody enjoys on vocals. If you have neutered sounding preamps you will have a neutered sounding vocal. So better isn't necessarily better but different.

I'm glad you like that API emulated compressor. A lot of people like the original. I never liked them, at all. I probably never quite learned the right trick to give me what I wanted? So I had to settle for 1176's & LA 3's, etc. And what about that Spectra Sonics 610 compressor/limiter? What the heck was with that thing? I had a pair of those and could never get anything to sound good through them. So history. It's these combinations of equipment that can be a make or break scenario. Especially since I think that a 5 dollar, single 5534 IC chip microphone preamp can sound really great when you plug in a real Neumann U67 into it. And a $19 Radio Shaft microphone can sound really great when you plug it into a API or NEVE preamp. Take the best of both and what do you get? Drunk.

Sloshing great sound for years
Mx. Remy Ann David

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JohnTodd Sat, 10/08/2011 - 10:04

OK, so I did some wiring tricks and ran my SM57 and Nady RSM4 through a Horizon Straightline passive DI box.

Mine is like that except it's the older SL-1.

What I got was lower gain and more noise. I thought passive stuff wasn't supposed to have "much" noise in it. All in all, sound quality wasn't changed appreciably. Now I know, this isn't the right way to use a DI box, and it wasn't designed for recording a vocal mic. But I would think I would have heard something different other than noise.

Perhaps the Jensen xformer is too clean?

RemyRAD Sun, 10/09/2011 - 11:28

John, I would be interested to know how you wired that Passive direct box to your preamp? Generally, you would need a XLR Gender change adapter, to plug the microphone into the XLR output of the direct box. You then take the high impedance 1/4 inch inputs and use those as the outputs to the preamp. The reason you are getting lower gain with more noise is that you are running the microphones into the passive direct box backwards. You have to realize that the passive transformer is not 1:1 in its winding ratios like a line level output transformer is, generally. Although this is not always the case such as the output transformers used in API equipment have the ability to step up output gain since it has 3 separate secondary winding outputs that can be connected for different output reference levels. Small low voltage circuit direct box transformers will generally have winding ratios of greater than 10:1 or when run in the opposite direction 1:10. This will determine the step up or step down in associated levels. In fact many direct boxes have higher winding ratios. For instance, most feature 50,000 ohm input impedances, while having 150 ohm outputs. That's generally a higher Winding ratio than what one would typically need for a microphone transformer. That should provide higher gain output from the transformer since that is merely a 50:1 winding ratio. So if output is lower, it's backwards. And so, you would be going into the unbalanced, 1/4 inch input on your preamp not the XLR input which would load down the 50,000 ohm secondary side of the transformer excessively causing that lower noisier scenario. That's why that 50,000 ohm secondary needs to be loaded into a high impedance direct input. And the problem would be excessively severe utilizing that passive ribbon microphone as compared to the SM57 since those are generally a higher output microphone in comparison. And of course, while impedance is expressed in ohms, as in resistance measurements, inductance, while expressed in ohms, is a slightly different concept to understand. Inductance involves the transference of power as opposed to resistance and is still expressed in ohms. So there is frequently a lot of confusion there for a lot of people.

The reason why the old-school microphone preamp's all utilized input " step up" transformers was to keep the microphone preamp's quieter. That's because input circuits in the bygone era could not produce enough gain with low enough noise levels. So the transformer with this step up windings ratios were added since they provided free gain amplification before the microphone signal hit the first input stage of the microphone preamp circuitry. And since tubes have high input impedances. And transistors have, Medium input (depending upon the type used), they are not loading down nor displacing the proper transference of gain that the transformer has provided. This is where impedance matching is crucial. And when needed, these types of Transformers can also be utilized (since they are bidirectional) as pads to create a loss of transference or gain with a pad may be needed but unavailable. This is where there is something of a significant difference between a knowledgeable recording engineer and a knowledgeable broadcaster. When you have to get something on the air, the thought of being quality conscious kind of goes out the window, where understanding basic knowledgeable policies don't apply. This is where theory and practice collide. You have to get something on the air in an efficient, listenable and comprehensible way. Whereas your typical recording engineer is more concerned about attainable quality level. Basically, this comes down to a high wire or, juggling act, so to speak.

In a different example I may give is simple microphone preamp design. Let's use for example the API 2520 Operational Amplifier. I don't have my data sheet in front of me but somehow remember that the input impedance of the 2520 is approximately 20,000 ohms. The microphone input transformer (Jensen 110 series for instance) has a 10,000 ohm secondary. It is not being loaded down by the higher 20,000 ohm input on the operational amplifier. So full transference of power is accomplished. If the input impedance was 150 ohms, this would greatly load down that 10,000 ohm secondary, dragging down the level & other acoustic qualities or improvements.

I hope this provides some better understanding? I am sure our better educated members will be fairly appalled at this description of my fundamental inaccuracies. What I am trying to convey is that understanding the basic knowledge of your tools provides for you better efficiency and at least some understanding.

Get it on the air now!
Mx. Remy Ann David

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JohnTodd Sun, 10/09/2011 - 18:38

Great post! I confused resistance with inductance - those ohms got me!

I wired the DI box like this: I have a passive attenuator box with XLR in and TRS out. That gave me the plugs necessary to go into the DI's HI-z in and XLR Lo-Z out to the preamp. Hey, I did wire it backwards, didn't I!?! Never thought of that. I looked up the schematic for this beforehand so I was sure I wouldn't let the magic smoke out.

I found a VST plugin that does xformer simulations. It is the TeslaSE plugin:

Don't know if it is accurate, but I can hear it doing something. Unfortunately, I don't really know what xformers sound like!


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Boswell Mon, 10/10/2011 - 04:52

I agree that you have the DI box wired backwards. The hiss is coming from the pre-amp trying to get enough signal out of a DI box working as an attenuator.

However, I don't think you did confuse resistance and inductance. Resistance (real), reactance (imaginary) and impedance (complex) are all measured in Ohms, whereas inductance is measured in Henries and capacitance in Farads.

At audio frequencies, input and output impedances of most professional audio gear can be considered resistive. Sometimes capacitance has to be taken into consideration, such as when using long leads from guitar pickups, but rarely inductance. It's the equipment designer's job to make the conventional connecting up of one piece of gear to another as easy as possible without inductance and capacitance effects getting in the way.

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JohnTodd Mon, 10/10/2011 - 07:44

It was a fun experiment. Now I've managed to get resistance, impedance and inductance confused. But I got it now.

The reason for the passive attenuator box was not to attenuate, but rather to allow me to go TRS into the FP10's INSTRUMENT jack. They have a 1Meg ohm input impedance. I did some test recordings and liked the way it made my SM57 sound - better quality high-end. My ribbon though got too boomy.

So, can I just make a xformer box? XLR IN ---> xformer ---> XLR out? Run the shield straight across bypassing the xformer so it will pass phantom power? My Nady RSM4 ribbon has no xformer in it. It's basically a loop wiht a ribbon motor in it.

What xformer? What ratio?

EDIT: I'm discussing two things at once - let me clarify.

I've abandoned the DI box and the 1 Meg ohm load idea. My idea now is simply a xformer box for my ribbon mic. I want a dedicated piece of hardware to compliment my voice. My voice is full and rich but I sing hissy and spitty. Of course I use a pop-filter anyway. The ribbon flatters my lead vocals already, just looking for "more magic". I usually track my backing vocals with the SM57 or my condenser if I need a bright sound.

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Boswell Mon, 10/10/2011 - 08:25

There's no real problem in making a transformer box given a suitable transformer. You would need to connect the shield across (interconnecting pin 1s on the XLR input and output) so that you have a ground connection but do not connect phantom power to an unbuffered ribbon microphone.

However, what would you hope to gain from using a transformer input? It will not turn an FP10 pre-amp into an API3124+ or a Neumann V476B.

If you look at the [[url=http://[/URL]=""]Jensen input transformers[/]=""]Jensen input transformers[/] web page, you will see that the maximum ratio they make is 1:10 due to high-frequency fall-off with ratios much higher than this. A 1:10 transformer will give you 10 times the signal voltage output from your ribbon, but a 30 Ohm mic will appear as a 3KOhm source to the pre-amp. In impedance terms, this would be too high for a standard mic input but OK for a pre-amp DI input, although no guarantee that it would sound anything special.

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Boswell Mon, 10/10/2011 - 09:12

No, not at all, if what you want to experience is the difference in sonic qualities between using the standard microphone inputs versus a DI input via a microphone transformer. The DI inputs of the FP10 (front panel TRS jacks on chans 1 and 2) are only 5dB less sensitive than the microphone inputs, so you should not have any signal level problems.

There is no impedance problem as the DI input is 1 MOhm, but a further experiment would be to wire a 100 KOhm variable resistor across the transformer output (DI input) and listen to what happens to the vocal quality as you change the effective input impedance of the pre-amp from around 90K down to a few KOhm.

RemyRAD Tue, 10/11/2011 - 15:24

Actually, the Jensen transformers for microphones are available in 1:6, 1:10 & 1:15. The JE 115 versions are what are now being used in API 512/312 preamps where they used to use the 110 version before. And Jensen's own 990 op amp that he designed utilizes the 1:6 transformer. And yes, utilizing an actual microphone input transformer to the direct input of your FP 10 should work amazingly well. Having the potentiometer across the secondary will give you the ability to have variable impedance. You will discover not only changes in level but in the tonality/response. There are as many crappy microphone transformers out there as there are good ones. The older ones (Beyer/UTC/Triad/customs by console manufacturers) many people pooh-pooh over the Jensen/St. Ives/Marinair types. But those earlier ones plenty of hits were recorded with so only you can be the judge. I have 20 API's with both Jensen's, Beyer & original API transformers and they all sound fabulous and most folks (except for some folks like us) can't tell the difference of what they're listening to. They can only tell the difference when they look at the specification sheet and test data. That's important if you listen with your eyes. You really don't want to use that attenuator box either. If you need phantom power for a microphone (which you don't seem to need) you need to purchase an outboard phantom power unit. But you don't need that what the 57 which can live through that and you absolutely don't want that for a ribbon of any kind unless it specifies it's necessary (i.e. active ribbon microphone). A ribbon microphone without an internal transformer is simply a micro amperage fuse which will generally blow up as soon as you plug it into Phantom power. So just get yourself some of those transformers and make sure you don't wire it up backwards again. The microphone goes into the low impedance side and the high impedance side goes into your DI input. The direct box works backward. So basically with the direct box all you need is an XLR female to female gender changer (such as a rewired microphone cable as opposed to an XLR barrel). So try the direct box again and take the 1/4 inch inputs of the direct box and utilize those as the output (Only one is required you don't need to loop through) to the DI input. Then let us know how it sounds?

Ear on Rear
Mx. Remy Ann David

bigtree Fri, 09/30/2011 - 16:58

John, I'd wait and save your dollars for something significantly superior. Your vocals and artistic talent deserve better. Whatever you are stepping up from can't be much better. If I was you, I'd even shop second hand for something around that price instead of either of these on a retail price comparison.

Hope that helps.

bigtree Fri, 09/30/2011 - 18:01

Well deserved.

Note; your overall mix will improve with good pre-amps compared to the lower end mushy mids etc from those starters valve pre's. Keep that in mind when you are struggling to get everything to sit right during mixdown.
To be frank, I don't know if I would go for a tube pre at this stage of your game and budget either. The tube design is adding substantial cost to the build, maybe 1/2 to double the cost so, you better be paying a lot more to get any value from and tube pre . Always look at the big picture when buying something. Look at design cost to your door: , shipping and handling, marketing, manufacturer and dealers profit and what you have left in actual value after all that?

I'd go for a very good FET design. You will get more mileage out of it. Also, IMHO, tube gear has to be stellar to reap the benefits. High end tube gear has balls and silk but low end is mush and mud.
And this as well: If your converters aren't clean, everything you put through them is worse.

You need to take one step at a time and improve things where they count. Don't waste your money on something marginally better.

I'll think of something for you, others should be chiming in with recommendations I'm sure.

Maybe a used FMR RNP , not sure, never owned one but there is something much better for you I'm sure....