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Warm Audio TB12 Pre-Amp Review

warm audio tb12 review


Warm Audio Tone Beast Review. The TB12 is a single channel microphone preamp with complete flexible tone control and cinemag transformers at an amazing price.

Review Preface:

No matter what your recording source is, getting that ‘perfect’ tone is a battle that typically depends on A) How full your microphone locker is, and B) What selection of preamps you have to hand. If you are like the majority of us, and don’t exactly have the loads of cash to throw at building both of these collections, or even have the experience to be fully confident in what you are buying, then manipulating your ‘hardware’ tone in a heartbeat could be made easier with the Warm Audio TB12; or ‘Tone Beast’.

So many hardware factors such as; the type of capacitors used, the materials used in the transformers, or the input/output transformer mix, can all come together to make a litany of fixed physical potential. Here at The Pro Audio Web Blog we are privileged to perform the debut review of the Warm Audio TB12, and believe that this unit can keep your wallet happy, whilst at the same time as being a serious trial and error exploration tool that can massively influence, and improve, your workflow or recording practices. The fact that the TB12 preamp is an one-unit rack-mountable piece of prime outboard real-estate is an feat in itself when you consider that it allows you to shape the sound by selecting what type of output transformers (Steel or Nickel core), (Electrolytic or Tantalum capacitor based) operational amplifiers, and even the input/output ‘saturation’ mix. We believe that you will find some strong conclusions from this review, and hope that you enjoy the ride!

Unboxing and Build Quality:

Okay, Warm Audio’s choice of packaging is certainly on the quirky side, but seeing as we don’t want to spoil the in-jokes or hidden messages that you may come across, we won’t delve quite so deep into an explanation for these. We will say that it is refreshing to notice these playful additions, and that it is certainly refreshing to see a real sense of humour coming from a very ‘human orientated’ company. It has given us many a smile during this process!

Moving on to the basics, the TB12 arrives in the standard brown box, where it appears to be satisfactorily suspended inside to protect the beast during transit. We experienced no issues to get to the product, and it comes with an external 24V power supply (to limit production cost and pass this on to the consumer), and finally a very detailed operation manual. Noting that the TB12 can not only be a very serious piece of gear, but also a learning curve, the detail that has gone into the operation manual will most likely effect your thoughts into how you craft a tone with hardware, not just positioning. For this reason we can give a big thumbs up to the ‘wizard’ boffins at Warm Audio for explaining this in plain English (obviously depending on your locale).

When you cast your eye over the unit you will notice that the faceplate is an very distinctive orange colour that seems to constantly draw your eye back and forth to the unit; for better or worse. Unlike the faceplate, the rest of the unit is crafted out of black textured sheet metal, with white details for good measure. Now moving back to the functions of the front panel, the rotary dials used are of a high grade that gives a satisfying tactile feedback ‘click’ and again, the ‘Gain’ potentiometers feel very solid, and move in 0.5dB increments. In terms of the physical switches there is nothing remarkable to note, they simply work in a fluid manner as expected. Upon inspection the XLR inputs do not appear to be of the ‘Neutrik’ standard, but nevertheless still function without flaw.

It has to be said that so far everything that we have discusses regarding the build quality lives up to expectations, and we estimate that this strong unit will survive many years of use. However, as you all may know, here at The Pro Audio Web Blog we like to go into the smallest of details. During our testing of this unit we found that first -20dB output meter LED appears to be substantially brighter than its other counterparts. Even in a well-lit room, this simple feedback appears to become a beacon that, on the whole, is actually quite distracting. Taking into consideration a generalisation about studio owners and their environments, we know that the majority are located in a hole in the ground, or indeed in a poorly lit room. In these situations this LED has proven to mask the brightness of the other, possibly more important, meter readings thus leaving us a tad dazed.


The TB12 is certainly not sure of features! It is an extremely comprehensive piece of kit that has almost anything that you will ever need in one place. As both the operational amplifiers and transformer designs has already been outlined within the preface we shall simply detail all the extras that are found on both the back and front of the unit.

Beginning with the unit faceplate we immediately notice that, just like the back, there is an microphone input to save you the worry of having to route through the back of your rack-mounted unit, and likewise there is an instrument input right next to it; an absolute godsend in many a situation. Additionally there is an impedance selector to partner with your instrument input so that you can appropriately tailor the signal to that of instrument that you choose to record. Likewise you have the Line-In selector, a -20dB pad for all of those extra-hot signals, a 180° ‘invert’ phase reversal switch, a fixed low-cut (or ‘high-pass’ -‘HPS’) filter that removes all unwanted sounds below 80Hz… and finally a 48v (phantom power input).

As we arrive to the back of the unit there is the 24v AC power in from the external power supply, your ‘Line In’ jack, XLR mic input, an XLR balanced output, and TRS (balanced) jack output. What is rather impressive here is that Warm Audio have included an insert send or receive so that you can route your signal to an external compressor, EQ unit, or perhaps to even use the TB12 to add some coloration on a routed master bus. In terms of features, all of us here at The Pro Audio Web Blog are seriously impressed with what is on offer here! So far it punches well above its weight, and with this in mind I think that it is best to move on to the ‘Sonic Performance’.

Sonic Performance:

The TB12 has a choice of circuitry for the user to route for a greater control over the signal. You have options for input amplifier, the x731 and the x18. Both op-amps do not sound that different at first, but through advice from Warm Audio and my own testing, pushing them to saturation point, you get the best out of the amps. Both colour the signal pleasingly but the x18 became my preferred choice as I found it had a brighter quality with a thicker body with a higher saturation point. However if you wish to change the op-amp, Warm Audio encourage you to swamp in other amps of which there are recommendation on their website. Granted, this is not something that the everyday consumer should attempt because of the associated risks with the delicacies of circuitry, but if you are an experienced user with an background of electrical engineering then feel free to go on right ahead; if Warm Audio encourage it, then who are we to argue with them. In fact I believe that this shows how much confidence that they have in their products.

As we come to the output circuitry, the TB12 sports two output transformers; one steel and one nickel. The Steel appears to have a generally thicker tone with a real punch in the mid frequencies when driven hard. This is certainly a contrast to the Nickel, which has a more modern brighter tone, and the high frequencies cut through with an increased presence than that of the Steel transformer. In fact, if you use the Nickel transformer with the X18 op-amp then you will experience a pleasant tone that works really well with shiny guitar chords. During use, and used modestly, you will find that the Nickel has some real bite to it without encompassing a harsh jagged tone. Certainly it has smoothness about it that does not leave transients being over-presented, but if you are looking for your input source to stand out and have that presence within your mix then this could be your man. When used with any fast acting ‘transient’ instruments such as kicks or snares you still get the mix of bottom end weight with an identifying sheen that you need during the mix process.

With the TB12 you can experiment your heart out with an endless sea of characters that are immediately to hand. Whilst I fully appreciate that most will experiment when they first encounter the unit by pushing it to its very limits, I must highlight that that this is a dirty crunchy tone that needs to be used with taste. Realistically some genres do suit this potential, but if you really are recording some serious takes then please go back later… just route the signal back through your DAW and into the TB12, it won’t hurt!

In terms of an immediate real-world performance, the TB12 has an outstanding amount of headroom that allows you to get the most out of your microphone and source. The range of tonality, control, and diversity of sound that the TB12 delivers is certainly not something that you can pigeonhole, and therefore we won’t embarrass Warm Audio with even trying to draw any parallels. All we can say now is that the technology under the hood allows you, through experimentation, to achieve some classic sounds that normally would cost you an awful lot more. The only real minor sonic disturbance found was when the low-cut (or high-pass) filter was engaged. This increased the overall noise floor, but it isn’t something to hugely worry about because it will only possibly become an issue with using low-level input devices (ie. ribbon microphones). Honestlythough, we could go on forever trying to describe every inch of our experimentation with this unit, but we could not possibly cover it all. This is something that you need to play with; because once you do you cannot stop.

Review Conclusion:

The Tone Beast certainly lives up to its name! It is crammed with functionality and flexibility for the budding engineer, semi-pro or even the professional studio engineer. It is an excellent unit that offers such fidelity that you normally could not achieve without owning a massive microphone cupboard, or pre-amp backline. With the TB12 you have almost endless degrees of operation. You can use it lightly, hard-driven, or everything in-between, and we love it! We do however have an issue with the blue LED, and the higher noise floor that is increased when the ‘low-cut’ (or ‘high-pass’) filter is input, so these minor grievances have deflated us somewhat. If these issues can be addressed then we shall award the TB12 with a full five out of five, however for now we have to award a four-and-a-half rating.

Edd Harris & Chris Pavey

Edd Harris & Chris Pavey - 4th August 2013

US RRP: $599.00 | UK RRP: £529.00

Editors Rating:

Four and a Half Star Award
Warm Audio TB-12
4.5/5 stars
Warm Audio Tone Beast Review. The TB12 is a single channel microphone preamp with complete flexible tone control and cinemag transformers at an amazing price.