You will surely have spasmodically wanted to try an instrument that is difficult to find, which you cannot procure or listen to in any way; but what happens when finding it at your fingertips this ends up behaving in a completely different way from what you expected? It is a bit of the story that closely concerned me with the new Presonus ADL 600; I have always been fascinated by the instrument, given that there is a lot of news on the net, such as to create a sort of mystical aura around it. Illustrious names that sponsor it, references, references and hints, but never a word about its sound texture or its strengths or weaknesses. Certainly the product, being designed by Anthony De Maria, can only be synonymous with a professional instrument; certainly the signal path has been studied down to the smallest detail, but why are we only talking about its high components? Does this preamp have a sonic soul, or is it just a well-designed enclosure with lots of beautiful light tubes to throw smoke in your eyes? Does the light from its valves warm the heart and caress the ears? The cost is high and the advertising generous. Will there be all the requirements to place the ADL600 on the podium of Top products?
First impressions:
At the first visual and tactile impact, the Presonus ADL600 (Fig.1) is captivating with a refined and elegant style. Very intuitively, each switch, rotary cursor, linear or not, placed on its generous front panel has been placed in the right place and at the right distance. The upper panel is full of ventilation slots that allow you to almost clearly see the six valves, the generous toroidal transformer and anything else that I will describe more accurately later. The two entrances INSTRUMENTS are placed on the front panel and accept balanced and unbalanced 1/4 inch jacks for guitars, basses, Fender piano etc., while for the line signals of keyboards, drum machines and more the house has set up two inputs (one on each side ) in XLR format on the rear panel (Fig.2). In order to use the XLR line inputs, we will therefore need adapters or a special male + XLR jack cable or a DI passive box. Let's now move on to the tests and some setting advice trying to concretely understand the potential of the Presonus ADL600 appointed to TEC AWARD 2006.
Male Voice:
For the test, specifically a voice that moves between the baritone and tenor register in a lyrical style, I placed an excellent NEUMANN U87AI at about 30cm from the mouth. On the Presonus I inserted a preamp of about 40dB, the HP filter at 40Hz and the impedance selector on 900ohm. The mid-lows of this performance are round and defined with clear and present central mids, even the mid-highs retain a character of extreme naturalness. The beauty is that even with high lyrical character the Presonus never went into “overload” crisis in the input stage, demonstrating great capacity for “headroom”; this is a very important feature because it allows any engineer to concentrate completely on the output signal routed to the recording track, and believe me, it is an added value that few machines have.
Female Voice:
The type of voice for this test is that of a very young singer who moves between the alto and mezzo soprano register. The singer has performed various performances of different genres, interpreting among other things a beautiful piece with a melodic character by Christina Aguilera, fertile ground for trying out the ADL 600 at its best. The voice heard in acoustic has a marked clarity, perhaps at times excessive , at the expense of thickness, I am referring in particular to the high register. During the period in which the singer kindly offered her collaboration to test the PRE in question, I had only 2 microphones available, the TLM 103 and the new AKG 414. After making various "Takes" with both microphones I opted for the Neumann as the source was returned with a softness greater than 414 on the high areas of the spectrum. In this particular case the Neumann found the best compromise with the characteristics of the voice described above. Given the heterogeneity of the dynamics, the piece has relatively low verses compared to the opening of the chorus and the special, so I articulated the phases of the section reprise (Fig.3), that is, I preferred to record the verses first - setting the ADL 600 preamp around 55 dB - and then the chorus, with preamp around 40 dB. In doing so I was able to capture both the warmth and detail of the first part and the high definition of the upper area, without running into the risk of "Overload". The only unpleasant aspect of this type of take is that it forces the singer to stop the "Take" to move from one area to another resulting in emotional fragmentation. The result, however, in a technical sense, remains very valid. 
On the verses the result is really exciting, airy, in full respect of the sibilants, so detailed that it was even possible to feel the crushing of the tongue; unfortunately the same result was not achieved in the chorus, the ADL 600 did not change the dynamic timbral gaps of the interpreter at all. In order to be able to obtain a more pleasant result, however, I had the following repeated at a later time "performance", trying to find comfort by lowering the impedance with the special dedicated knob; from the 1.500 ohm set at the start I dropped, with a first click, to 900 ohm, then to 300 ohm and finally I stationed on the lowest value provided by the machine: 150 ohm. After carrying out all these tests, according to my experience and my taste, I believe that the latter position has proved to be the most effective. Acoustically, proportional to the lowering of the impedance, there is a noticeable smoothing action in the upper part of the spectrum with relative loss of preamplification. In this specific case I had to regain 5 dB with the Gain section, thus obtaining a greater warmth of the more controlled "S" in a more amalgamated tone; clearly I lost a bit in detail and linearity, but for this voice, at times thin and harsh in the medium-high register, this operation contributed to a more than acceptable result.
Contrabass:
The double bass for this test was miked with a AKG D112, placed at the height of the bridge, and with a NEUMANN U87 placed about 50cm away and slightly higher than the first, taking advantage of both channels that the Presonus offers. The sound obtained with the D112 is of great definition on a region of usually mixed frequencies, in particular I am referring to the "Range" 150Hz - 400Hz so the result was more than satisfactory. The "Punch", the roundness and the attack seem the most promising features for this recovery. Thanks to the U87 capacitor we were able to obtain a good blend between direct and ambient sound, the result was great realism. The sound recorded and listened to through the PMC AML1 monitors was similar to that naturally heard shortly before in the shooting booth during preparation. The right blend of these two mic signals can really provide a wide tonal color palette that you can adapt to any production, mix or arrangement.
Acoustic guitar:
For the recovery of this instrument we have relied on NEUMANN TLM103 (Fig.4). The guitar used for the test is a decent TYLOR with cutaway. Also for this test I took advantage of a dear friend, the talented guitarist Giuseppe Rapicano who, thanks to his great musical versatility and his range of guitars, helped me to better discover the behavior of the PRE with the 6 and 12 string instrument. In this rehearsal we abandon the Blues style for a while and adopt the Country and Pop style. The Presonus immediately makes its presence felt, or rather "not felt", in the sense that the fidelity reproduced is disarming beyond any other tube; a guitar signal very similar to the original is returned until it is revealed that the guitar model used is not exactly one of the very expensive ones of the “non ti perdono!” series. With great dignity this test is also successful. Unfortunately, only the treble of the guitar appeared clumsy and subtle, but that was because of the instrument and not the ADL 600.
Electric bass:
The electric bass must be inserted in the "Instrument" input on the front panel (Fig.5) as well as guitars and all pickup instruments in general, including the piano Fender Rhodes and if we want we can also use this section as an input for synthesizers with low output gain. The manufacturer has set an impedance a on this type of input 100KOhm. The bass is a Yamaha five-string with frets. The DI section demonstrated excellent cleanliness and thrust, providing a good enhancement of the electronics of the connected instrument. Just enough energy, on the phrasing great definition of the notes, on the accompaniment attack and body were not lacking and even with the slap there was no “overload” even with the preamp boosted.
Line inputs:
For this test I connected keyboards, synthesizers, drum machines and a CD player. The LINE inputs on the ADL600 are in XLR format with impedance fixed at 2KOhm. Compared to what may be the microphone recordings, the preamplification of the LINE inputs has less responsibility, in the sense that usually one has to deal with source signals that are already strong and formed enough; despite this the Presonus has managed in every way not to limit the depth of the bass of a synthesizer managing to return the tremendous 40Hz and all the density of the spectrum typical of certain signals; excellent work also on the containment of impulsive and fast transients of the "Drum machines", of the complexes "Style" rich keyboard arrangements, to enhance and refresh old and new recordings from the CD player. All always with professional signal management.
Acoustic Piano:
This majestic instrument is one of my favorites because its conformation allows it to cover almost everything "Range" audible, allowing the performer to play with the notes and frequencies. But when I have to capture its sound, the big problems begin, especially if the tone of the piano is dark and full-bodied. Normally in traditional studios there are no microphones and preamps suitable for this purpose, you arrange yourself as you can, sometimes you find good compromises but it is very difficult to find the right microphone and the right PRE for every occasion. In this specific case I was able to get a select pair of my favorite microphones: i DPA 4011. The first "Step" is outdated, but how will the ADL 600 behave? Only two very neutral PRE models have always really satisfied me for this type of shooting, let's see what degree of linearity we will be able to obtain from this test. The microphones were positioned with the coincident stereo imaging technique XY which is obtained by forming an angle of 90 degrees by intersecting the two microphones (Fig.6). This specific recovery also manages to provide excellent monocompatibility. Opening the piano lid as wide as possible, I positioned the two microphones in the center and slightly back to the hammer line as if it were a vibraphone take just to be clear. I love very much, especially in pop music, to get a piano sound ready, defined and rich in attack, practically a la Danilo Rea. 
For a further test I used 2 classic microphones U87, which usually make up the kit "Standard" of any professional studio, placing them (after selecting omnidirectional shooting polarity) on a horizontal pole at a distance of about 50 cm between them; in this stereo, spaced configuration A + B, with microphones facing the opening of the piano at about 1 meter away, the result obtained was what one would expect from this type of recording: a very linear pre-amplification, basically a great timbre with a high frequency response, characterized by the typical ambient sound paste (Fig.7). Compared to the previous take of directional character, the fast attack of the hammers on the strings is considerably lost, but on the other hand a great tonal-harmonic color is soft and enveloping, very suitable for a classical or Jazz context, in particular for solo piano. Also in this case the Presonus ADL 600 lends itself with professional characteristics to any choice of sound recording. I could also stop here but it seemed right to also give an opinion on how the ADL 600 sounded with microphones that were not so famous but well made, also because our PRE presents a natural versatility to experiment with other tonal solutions. My choice fell on a select pair of AKG 414 ULS, well balanced for this type of recovery, do not exaggerate in any part of the "range”And have a very pleasant sound texture. Again I did perform takes of different genres, from classical music, to jazz, up to a very commercial pop where there are no great plays of harmonies and harmonics; obviously I kept the same settings made with the DPA, except the PRE parameters. The result in this case too was very satisfying, more than I expected; my only perplexity was that the ADL pairing with the 414 ULS suffered from very fast piano passages, especially in the "Range" mid and low frequencies. Usually when I have to deal with colored microphones, especially coupled with tube PREs, I run into problems of signal attack with the consequent problem of too mixed sounds, a phenomenon perhaps not perceptible by a not attentive ear but noticeable by the experts of the sector. The ADL 600 was also excellent for this test, demonstrating great fidelity in full respect of the sources.
Over Drums:
On drum overs, with a select pair of AKG 414, the Presonus managed to detect both the legendary touch with ease of the brushes that the energetic blow of the chopsticks, including cymbals and drums, all with great precision, realism and spatiality in full respect of the transient response. Although it is a very fast instrument, especially on metal surfaces, the Presonus has never failed in the entry stage, both for the riding on the cymbals and for the depth of the toms and eardrum. Even the snare drum has been returned with all its generous and spicy "hit" funk on the middle mids, in those typical hits between the edge and the skin. The brush rubbing on the sandblasted skin of the same snare is equally good. Also in this test the instrument proved to be sensitive and reliable in the face of the complexity of the dynamic range and frequency response of the battery seen from above.
The Color Detail:
When you are lucky enough to have a good range of professional machines, before giving an opinion on a specific product, I prefer to stress the instrument with different sound sources; generally the first impression is always a little distorted by the time and source used. In this case, from the first moment I connected the usual Klotz microphone cable, complete with a golden Neutrik connector at the poles, I immediately realized that I was in the presence of an instrument with excellent performance in terms of precision, detail, neutrality, quietness and considerable headroom. All this made me reflect on how sometimes the saying “dress does not make a monk” is true. Specifying, it is important to say that the ADL 600 is certainly not a tube machine that sounds like a transistor but that in its possibilities, if desired, it could provide a very accurate and clean signal like a solid state circuit in pure class A Clearly by gaining on the input stage we have the possibility of providing more harmonics to the signal, without however encountering euphemisms with a too tube-like flavor as could happen with machines such as Universal Audio, Avalon VT series, Tubetech etc. To my surprise the ADL 600 manages, on vocals and any other instrument, to return that detail from 5000Hz ai 10000Hz always consistent and intact with respect to the source; even the "S" are never translated into some kind of "F" or similar, but are faithfully returned "sibilants". Of course, one always hopes to deal with quite polite performers! Voices clumsy, flat, of approximate quality and non-classy guitars, would always remain so. However, one or more solutions are open to experimentation: for example on the voice one could use not a NEUMANN TLM 103 type microphone but a warm U87, if not even a powerful tube (Fig.8); the same goes for the other brands, that is to choose models that are more colorful rather than neutral, but always of great class. Another solution could be to lower, with the appropriate selector, the impedance value, especially if you are dealing with some female voice with a thin and clean timbre. 
With each shot you will see how the upper part of the spectrum will noticeably smooth out with consequent loss of a few decibels of preamplifier, a sacrifice that will cost very little since the ADL 600 of dB has to sell. The section impressed me a lot DI as well as the quality of the line inputs, truly professional quality, capable of adapting to any signal level, from the weakest to the strongest; do not forget then, should there be the need, that you can count on an effective attenuation PAD of 20dB. I recommend the product to anyone who needs a very versatile, friendly PRE with a soft character that adapts to all circumstances. I think it's really one of the few machines to recommend as the main PRE in a professional studio setup. Many readers at this point will be able to tell me: “but it is yet another "Outboard" ten and praise, characterized by a review without blemish or smudge? " The machine for how it sounds is 10 and praise, but being a "complacent" instrument, even if it has an excellent tone, it does not have the aggressiveness and the marked flavor of other colleagues; this is not necessarily a bad thing as it plays the role of "landlord", lending itself well to host other PREs who will act as "specialists" for sporadic and specific occasions. The only real drawback is the price, which remains in line with products of the same kind, in short, quite high considering that the Presonus house has never been considered the "TOP" for a hyper professional studio; perhaps it would have been good to bring back the Anthony De Maria lettering in large, much appreciated by experts in the sector, and in small the Presonus brand. Sometimes very small marketing games can make an offer more attractive and arouse greater curiosity and interest from the public.
Look at the internal architecture:
As always, I dedicate a little space to the manufacture of the product without exaggerating in a detailed description of all the components. I don't like to bore the reader by giving only numbers and abbreviations of what I see inside the machine, I prefer to convey my impressions as a “spectator” on the choice of components and on the audio path. As I said earlier, at first glance the instrument is well cared for in all the smallest details, the chassis is built with military standards and is strong and robust. What I don't like are the VU meters (Fig.9) (the same I put them on my first self-built preamp of "Nuova Elettronica" in the mid 80's), I would have preferred a new "design" (strictly analog).
By unscrewing and lifting the top panel, you can look inside the machine. What I see is a very accurate realization, all with discrete elements and with super-audio devices such as the totally isolated power supply (shielded) in its dedicated housing (Fig.10), all this to avoid spurious magnetic fields, hums and other sound impurities (working with very low voltages). The power supply is also totally built with discrete elements. The valves are locked with metal grids to prevent movement (perhaps to also attenuate resonances). From a closer look it seems that adequate internal cooling is missing, as an ignorant I would have added a fan "Low noise", in order to appropriately convey the heat of the valves. However, after careful documentation on the world of tube circuitry, I understood why whoever designed the instrument did not think about it: when you work with very low voltages such as microphones it is all too easy to introduce spurious noises. I also found that the preamp tubes don't have much need for heat dissipation. They are even of excellent quality "Switch", switches and valves for Military use; impeccable internal cleaning, very synthetic printed circuit and high quality. All valves are selected (Fig.11), internally known two Sovteck: 12at7 which are equivalent to etc81. The sound produced is musical, warm and clean, rich in harmonics and well balanced. In my opinion it was an ideal choice, in fact we normally find these valves in the PRE section of a Fender 75 combo and other Fenders and are usually used for reverb send or phase inversion. Internally there are other valves (two per channel) that make up the internal harmony and the bill of the ADL600, the Sovtek 6922 which are cascaded. At this point I just have to thank my two friends Savio Aversano and Nunzio Infantozzi who helped me understand the reason for the choices of components by the designers of the ADL 600 and advise all of you readers to listen to the "Takes" prepared for you. Happy listening everyone!
USEFUL INFORMATION:
Producer: Presonus
Model: ADL 600
Website: www.presonus.com
Distributor: www.midimusic.it
Price: 2.450 + VAT
You certainly experienced yearning for a hard-to-be-found new instrument, which you aren't able to get or listen in any way; but what happens when, once you have it at hand, it turns out to behave in a completely different way from what you expected? This is more or less what happened to me with the new Presonus ADL 600; I've always been enchanted by this instrument, due to all the reviews on the web, so much that they have created a sort of mystic halo around it. Renowned names to advertise it, references, notions and recalls, but never a word about its sound grain or about its pros and its cons. Indeed this product, which have been designed by Anthony De Maria, could not be less than a professional instrument synonymous; Surely the signal path has been studied in each aspect, but why do they only talk about its high level component part? Is this preamplifier endowed with a sounding soul, or is it just a well designed shell with lots of bright valves to pull the wool over anybody's eyes? Does the light of its valves warm up our heart and caress our ears? The price is high and the advertising around it is very generous. Are there all the necessary requirements to put the ADL 600 on the top-class products podium?
First impressions:
At first sight and touch the Presonus ADL 600 (Pic.1) shows a neat and elegant style. Much intuitively every switch, every linear and non-linear rotary cursor, has been placed properly and generously at the right distance on its front panel The upper panel is full of ventilation slots which let you see the six valves almost clearly, the big toroidal power transformer and anything else I'll carefully describe later. The two INSTRUMENTS inputs are placed on the front panel and allow balanced or unbalanced ¼ inch guitar, bass guitar, Fender piano jacks etc., while for the keyboard, drum machine and other input signals the house has put up two XLR connectors (one on each side) on the back panel (Pic.2). Therefore we will need, in order to use those XLR signal inputs, some adapters or a suitable + male XLR. jack cable connector or a passive Direct Injection Box. Now let's move on to testing it and give some set-up advice, trying to understand the potential of the Presonus ADL600 nominated for 2006 TEC AWARD.
Male Voice:
In order to test it, in this case we have a voice that moves between the baritone and tenor classical range, I placed an excellent NEUMANN U87AI about 30 cm apart from the mouth. Presonus set with 40 db preamplification, HP filter at 40 Hz and the impedance selector switch on 900 ohm. Lower-mid sounds in this performance are round and defined with clear and existent central mids, higher mids too are maintaining an extreme natural character. The great thing is that even with classical top notes the Presonus never went to overload problem on input signal, giving credit to its great headroom capacity; this is a very important feature for it allows every sound technician to concentrate completely on the output signal sent to the recording track, and believe me, it is an added value which only a few engines have got.
Female Voice:
The type of voice for this test is a young female singer's one that moves between the contralto and mezzo-soprano range. The singer went through different genre takes, performing a beautiful melody tune by Christina Aguilera, fertile field to test the ADL600 at its best. Listening to the voice in acoustic environment shows a strong sharpness, perhaps sometimes a bit too much, I mean the higher register notes in particular. At the time when the singer gently offered her collaboration in testing the preamplifier at issue, I had only 2 microphones in hand, the TLM 103 and the new AKG 414. After a few takes with both microphones I decided to go for the Neumann as the source was passing with much more softness than the 414 referring to the high range spectrum. In this particular case the Neumann microphone has proven to be the best compromise with the above mentioned voice's features. Due to the heterogeneous dynamics, the track features some relatively low verses in comparison with the chorus part and to the special part, so I decided to go for a section recording (Pic.3), that is to say I chose to record verses first – setting ADL600 preamplification at about 55 db – and then the chorus, at about 40 db. By doing that I was able to capture both the first part's warmth and the detail and the higher range high definition, without dealing with any overload risk. The only unpleasant aspect of this recording process is that it forces the singer to stop the take and jump from one part to another with inevitable emotional fragmentation. However the technical result is valuable. On the first lines the result is really exciting, airy, in full respect of hissing parts, so detailed that we could also hear the pushing tongue; However we didn't achieve the same result on the chorus part, the ADL 600 didn't improve at all the performer's timbre dynamic gap. By the way, in order to achieve a more congenial result, I had the performance done twice, trying to find comfort by lowering impedance through the assigned knob. I went down from the initial 1500 ohm, on the first attempt, to 900 ohm, then to 300 ohm and finally I settled with the lower value provided by the engine: 150 ohm. After all these attempts, based on my experience and on my personal taste, I believe this last position to be the effective. From an acoustic point of view it considerably shows, proportional to the impedance decrease, a smoothing action about the higher part of the spectrum related with the preamplification loss. In this particular case I had to gain back 5 db (via Gain section) getting that way a further warmth about the “s” sound, with a much more controlled and merged timbre. Obviously I had a loss in particulars and in linearity, but regarding to this type of voice, sometimes sharp and rough on the higher mid register, this intervention has helped to achieve a much more than acceptable.
Double Bass:
We've been using an AKG D112 microphone for this test, placed in front of the bridge (ponticello), and a NEUMANN U87 placed at about 50 cm and slightly higher than the other one, but both taking advantage of the channels provided by Presonus. The sound we reached by D112 is very defined about a usually dapple frequency domain, I particularly meaning the range between 150Hz and 400Hz, therefore the result has been widely satisfying. The punch area, the roundness and the attack seem to be the most distinctive features through this recording session. Thanks to the U87 condenser we were able to blend both direct sound and ambient sound getting a very realistic result. The recorded sound and listened through PMC AML1 monitors was similar to the natural one we listened inside the recording booth a while earlier during the planning moments. The right mix between these two microphone signals can really provide a wide board of tone colors which are suitable for every production, mix or arrangement.
Acoustic guitar:
In order to record this instrument we relied on the NEUMANN TLM103 microphone (Pic.4). The guitar we used for the test is a fairly good no shoulder TAYLOR guitar. Also for this test I took advantage of a good friend of mine, the excellent guitarist Giuseppe Rapicano who, thanks to his musical versatility and to his wide guitar set, helps me understand better the Pre's behavior by the 6 and 12 string instrument. This time we will put the blues style aside to turn to country and pop. The Presonus immediately let us hear, or we'd better say “not hear”, its presence, meaning that its fidelity recording is much more disarming than any other valve engine; the given guitar sound is very similar to the original one so to reveal that the type of guitar we used is not one of the most expensive ones, the kind that makes you say “I won't forgive you!”. With much dignity this test has reached a good result. Unfortunately only the high notes showed awkward and thin, but it was due to the type of instrument and not ADL 600's fault.
Electric bass:
The electric bass must be plugged into the “instrument” output placed on the front panel (Pic.5) as well as guitars and all the pickup instruments in general, including the Fender Rhodes piano and we could even use it as input for low gain pick-ups synthesizers. On this particular input the mother house sets a 100KOhm impedance. The bass we are using is a 5-string bass with keys. The DI section showed excellent boost and fidelity, highlighting the peculiar electronics of the instrument involved. A good amount of energy, great definition in terms of notes during the phrasing, attacks and body had not been missing on the accompaniment and also it never went overload with the slap, neither with heavy preamplification.
Inputs/Outputs:
For this particular test I connected keyboards, synthesizers, drum machines and a cd player. Outputs on ADL600 are 2KOhm impedance XLR line in. In comparison to the microphonic recordings, line ins preamplifications have less responsibilities, that is to say that usually they deal with sources which are already strong enough and shaped; Nonetheless The Presonus was able not to soothe the lower sounds of a synthesizer so to keep the hideous 40Hz and some signals distinctive spectrum density. Even on the transient impulsive signals limiting an excellent job was done, such as the fast ones of the drum machine, the elaborate ones from the style section, full of keyboard arrangements, even in improving and refreshing old and new recordings from the cd player. Altogether done with professional signal management.
Acoustic piano:
This majestic instrument is one of my favorites for its physique allows to cover all the audible range, letting the performer to play with the notes and with the frequencies. However when I have to capture its sound it is when all the big trouble starts especially if its timbre is dark and solid. Usually in traditional recording studios you don't find microphones and preamplifiers suitable for this purpose, you manage with what you've got somehow, sometimes you find a good compromise but finding the right microphone and the right PRE for all occasions is a hard thing to do. On this occasion I could find a selected couple of my favorite microphones: the DPA4011 ones. This way I went over the first step, but how will the ADL600 behave? Only two neutral types of PRE always truly satisfied me for this kind of recording sessions, so let's see how much fidelity we will achieve from this test. Microphones have been placed by the XY coincident-pair stereophonic technique which is based on creating a 90 degree angle aiming one across the other (Pic.6). This image can provide a very good mono-compatibility. With the top of the piano wide open I positioned the two microphones in the middle and slightly apart from the piano hammers as if it was for a vibraphone recording, I placed the microphones in the middle and slightly behind the hammers line I really love achieving, especially with pop music, a powerful, shaped and rich at the attack piano sound, in other words in the style of Danilo Rea. For a further test I used two typical U87, which usually form the standard set in every professional studio, placing them (after selecting recording omnidirectional polarity) on a horizontal rod at 50 cm distance between one another; in this stereo set-up, spaced A+B, where microphones are aimed to piano opening at about 1 meter apart from it, the result we got was the one we were expecting form this type of recording technique: a very defined preamplification, actually a strong timbre with a high frequency response, highlighted by the typical room sound grain (Pic.7). In comparison to the previous directional recording it shows a big loss of hammers fast attacks on the strings but on the other hand it creates a nice timbric-harmonic colour, soft and enveloping, quite suitable for a classical or jazz context, especially for piano solo. Still here the Presonus ADL600 lends itself to every recording choice with professional results. I could stop here but it does seem fair to also give an opinion about how ADL600 sounds with not-so-blazoned microphones but still of good fabric, also because our PRE features a natural versatility in experimenting many timbric-sound solutions. My choice was a selected couple of AKG 414 ULS microphones, well balanced for this type of recording, as they don't overact on any range part and give evidence of a pleasant sound grain. I had different genres takes done as well in this case, from classical music, to jazz and even a pop one which can be full of harmony and harmonics; Obviously I kept all the settings I previously had with DPA, except for the Pre parameters. The result was pretty amazing in this case too, more than I could have expected; My only doubt was that combining ADL with 414ULS, the fastest piano passages would have been odd, particularly in the lower mid frequencies. Usually when I'm dealing with much colored microphones, especially when combined to tube preamplifiers, I run into signal attack issues therefore with too much riddled sounds, perhaps a non-audible event from a careless ear but clear to experts in the field. This ADL 600 test was excellent as well, showing its high fidelity capability in full respect of the sources.
Over Drums:
On the over drums, combining an AKG 414 pair of microphones, Presonus was easily able to read off both the legendary touch of brushes and the forcible beat of sticks, including plates and kettledrums, all with extreme thoroughness, clarity and ambience spatiality, fully respecting transient response. Being a very fast instrument, in particular on the metallic surfaces, Presonus never had trouble on the input phase, both on plates riding and toms or kettledrums depth. Even snare sound was developed with all its generous and spicy funk slap toward the mid frequencies, by those typical edge and leather beat. As well as the brushing on the sandy leather of the same snare. Still in this test the instrument showed its sensitivity and reliability towards the complexity of the dynamics range and the frequency response by the drum which was recorded form above.
The Color Detail:
When you are so lucky to have a professional engine set at your disposal, before giving an opinion on a particular product, I prefer straining it with different sound sources; Usually the first impression is always a little bit distorted by the circumstance and by the source we used. In this case even from the first moment I connected the usual Klotz microphone cable, fitted with a gold plated Neutrik connector, I immediately realized that I was in the presence of an amazing instrument in terms of accuracy, detail, neutrality, quietness and remarkable headroom. That made me think about how true is the saying “sometimes the clothes do not make the man”. To be honest, it's important to say that the ADL 600 is not a tube engine that sounds like a transistor one but it is capable, if needed, to provide a very accurate and clear sound as well as a solid state class A circuit. Obviously while gaining a lot on the input side we have the chance to provide further harmonic sounds to the signal, but not running into valve ring euphemisms as it could happen with engines like Universal Audio, VT Avalon, Tubetech etc. Surprisingly for me the ADL 600 is able, with voice and any other instruments, to reproduce any detail between 5000Hz and 10000Hz, consistently untouched towards the source; even the “s” consonants never got to be some sort of “f” or similar sounds, but kept loyal to their own “hissing” sound. Obviously we always wish we could deal with rather well trained performers! Awkward voices, as well as flat and undefined or non-classy guitars, they would remain that way for sure. One or more solutions are open to improvement experimentation.; for example, we could use a warm U87 microphone for the voice instead of a NEUMANN TLM 103, or even go for a powerful valve microphone (pic.8); Same thing for the other brands, that is to say choosing some more colored types instead of neutral ones, but classy ones as well. Another solution could be toning down, by the appropriate channel selector, the impedance value, especially if you are dealing with some faint and clean timbre female voices. With each click you can notice how the higher part of the spectrum will appreciably smooth consequently with a decibel loss in preamplification, a sacrifice that will cost a little considering that ADL 600 in terms of decibels has enough and to spare. I was struck a lot by the DI section as well as the inputs, truly of professional quality, suitable to every signal level, from the weakest to the strongest one; besides, don't forget, in case you needed it, that we can count on an effective PAD that allows you to tone down 20dB. I'm suggesting this product to the ones who need a highly versatile and friendly PRE, with a soft temper suitable for any situation. I believe it to be one of the few engines to recommend as a main Pre in a professional studio set environment. Many readers could tell me at this point: “but is this the umpteenth first-class outboard, highlighted by a flawless review?”. Judging on how it sounds, this engine is a first-class one indeed, but being it an “accommodating” instrument, though of amazing timbre, doesn't show the same aggression and the strong flavor as its associates; this is not by far an odd thing for it takes on a “master of the house” role, capable in hosting other preamplifiers that will act like experts in isolated and specific occasions. The only one slight defect is its price, toeing the party line with same kind products, actually a bit too much considering that the Presonus house has never been seen as the top class when it comes to ultra-professional studio recordings; Maybe It would have helped a bigger Anthony De Maria inscription, very appreciated by the experts, and a smaller Presonus mark. Sometimes tiny marketing effects can really make an offer more charming and provoke much more curiosity and public interest.
A look into its internal structure:
As I always do in my reviews I'm dedicating a little space to the product manufacturing without going too far into an extremely detailed description of its parts. I don't like bothering the reader by giving him a series of numbers and acronyms of what I see inside the engine, but I prefer conveying my impressions as a “viewer” about the component part selection and the audio circuit. As said previously, at first sight the instrument looks very well-groomed down to the smallest details, the chassis is built in military standards and it is tough and solid. The things I don't like are the VU meter (Pic.9) (I used the same ones for my first “Nuova Elettronica” preamplifier that I made myself in the mid 80's), I 'd have liked a new design (strictly analogic): Unscrewing and lifting the upper panel, you can see the inner part of the engine. What I see is a very detailed construction, all with good elements and some superaudio solution as a totally isolated feeder (screened) inside a housing of its own (pic. 10), all this in order to avoid spurious magnetic fields, hums and other sound impurities (we are dealing with very low voltages): Also the power supply is entirely built with good elements. Valves are locked to a metal grid in order to avoid any movement (perhaps to ease resonances too). By a deeper look it seems to be lacking of an appropriate internal cooling system, knowing nothing about it I would have added a low noise fan, so to conveniently convey the valve heat. But after having been closely gathering information about the valve circuit system world I understood the reason why whoever designed this instrument didn't think about it: when you are dealing with very low voltages like the microphones ones it is so mush easy letting any spurious noises. Moreover I discovered that the amplifier valve don't require too much heat dissipation. Amazingly good are even switches, converters and military wear valves; Exemplary internal cleanliness, a very synthetic printed circuit board and top quality fabric.. All the valves are selected (Pic. 11), Internally I can notice two Sovteck:12at7 which are equivalent to ecc81. The resulting sound is musical, warm and clean, full of harmonics and brilliantly balanced. In my opinion it was the perfect choice, as a matter of fact we can find these valves in the PRE section of a Fender 75 combo and in other Fenders and usually they are being used for the reverb enter and phase inversion. Internally there are further valves (two for each channel) which built the internal harmony and the ADL600 fabric, the Sovtek 6922 which are connected in parallel. At this point all I can do is thank Savio Aversano and Nunzio Infantozzi who helped me understand the reasons behind the elements' choice by the ADL600 designers and suggest all you readers to listen to the takes I prepared for you. Have a good listen everyone!
Translation by Humbert of the Judge
