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Manley Labs SLAM Mic Preamp and Limiter

Leave it to Hutch at Manley Labs to design a product which makes we wonder why I purchased at least four expensive pieces of gear within the past few years. The SLAM! ($6,600) combines a pair of hybrid tube/solid state mic preamps with Manley's current thinking on electro optical (ELOP) limiters and FET limiters.

Leave it to Hutch at Manley Labs to design a product which makes we wonder why I purchased at least four expensive pieces of gear within the past few years. The SLAM! ($6,600) combines a pair of hybrid tube/solid state mic preamps with Manley’s current thinking on electro optical (ELOP) limiters and FET limiters. Plus, you have the option of being able to add a smooth-sounding set of ADCs and DACs. Couple all that with a very well-thought-out complement of analog I/O possibilities and one of the most comprehensive metering schemes I have ever seen, and you might begin to understand why the Manley SLAM! has been backordered for over a year.
Product PointsApplications: Tracking, mixing, post production

Key Features: Stereo mic preamp; FET and ELOP limiters; direct inputs; flexible routing

Price: $6,600 optional digital I/O board, $2,500

Contact: Manley Labs at 909-627-4256, Web Site.


+ High-quality mic preamp

+ Two limiter types

+ Easy to use

+ All-in-one value


– DAC direct out

The Score: The Manley Labs SLAM! is a very unique “all-in-one” box. If you need all its features, it is a more cost-effective solution than mixing and matching separate pieces of high-end gear.

Let’s look at the rear panel first. The balanced inputs are Neutrik Combo jacks that accept XLRs, TR and TRS plugs — which function both as mic and line level input ports. There is also a pair of 1/4-inch direct inputs which offer a choice of 100K or 10 Mohm input impedance. There are both transformer balanced (XLR) outputs and transformerless unbalanced (1/4-inch) ones at +4 dBu. The unbalanced jacks can also supply a consumer-level Ð10 dBu if one inserts the plug half way in. If the SLAM! has the digital I/O board installed, the balanced +4 dBu DAC output is active.

The user-installable digital board (which fills a three-inch square panel on the chassis’ rear) includes AES/EBU XLRs for I/O, a BNC for word clock input, five toggle switches for DAC filter choices (three), ADC filter choices (three), noise shape choices (two), dither (two), and word length (three choices). There also is a single rotary control, which gives seven choices for sample rate: 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz, as well as AES/EBU data input rate, word clock and Superclock.

There are also 12 little patch bay-type bantam jacks, which control side chain inserts and linking parameters for SLAM!’s four limiters. Ten are active (leaving a pair available for custom modifications.)

The power connector is a 16-pin jack, which connects to a cable coming from the external power supply, roughly the size of a vintage Telefunken power box.

The front panel is bilaterally symmetrical about its power switch. For each channel, there are two large pots, two smaller ones, two rotary, and two toggle switches. The source selector chooses the input to the SLAM!: DAC, line, DI, mic, mic with polarity reversed and mic with 100 Hz high-pass filter. The input pots have different gain ranges depending on the input choice; the output level pot sets the level going to tape or disk and also is the “gain makeup” control after the opto limiter. The small pots are threshold controls for the opto and FET limiters, while the toggle switches give the user two choices for the HP filter in the opto limiter’s side chain and two attack choices for the FET limiter.

Underneath two large VU meters (which flank two multicolored LED ladders) are four more toggle switches and two pushbuttons (to switch in the limiters). The first toggle is a three-position switch which gives choices for stereo linking, dual mono, and which channel(s) control the limiting action. The second selects the source for the VU meters, while the third allows the signal feeding the VU to be attenuated by 3 dB or 6 dB (so you can really slam them without doing damage to ‘the needles’). The last switch is a mode control for the behavior of both the VU and LED meters. Space restraints preclude my detailing its numerous possibilities but, if you are curious, simply check out pages 12 and 13 of the SLAM!’s 30+ page manual on the Manley website (

In Use

Since it is such a unique product — and I have nothing in my studio remotely like it — I will compare it with some of my own arsenal of separate components, whose total cost far exceeds the price of the SLAM! Specifically, I will compare subsections of the SLAM! with my Apogee Trak2, Manley MicEQ500, Manley VoxBox, and Amek 9098 “RNCL” Dual Compressor/Limiter.

The mic preamps are quite different from any previous Manley preamps. They offer 60 dB of gain and, since you can score another 20 dB from the SLAM!’s output circuitry, it’s safe to say that you can record the quietest lute with a ribbon mic and not feel a need for additional gain. Borrowed from Manley’s “Steelhead” phono preamp, their hybrid design provides the low noise of FETs and the high headroom of tubes. They do not sound as “tubey” as my Manley MicEQ500 and are quieter than the preamp in my VoxBox. It is as clean-sounding as the preamp section in my Apogee Trak2 but, due to its input transformer and tube second stage, provides a bit of added warmth. It is not a “character” preamp; simply a warm, clean one. I really liked it. The 10 Mohm choice on the DI input made my vintage Hofner bass sound much brighter than the VoxBox did.

The limiter sections were quite interesting to me. As an engineer who does both classical and acoustic jazz recordings, I have simple, but specific, uses for dynamic processors. I always use “two- bus” stereo compressor/limiters somewhere in the chain on most of my classical recordings. For example, when I produce, the Sonya Kitchell band, I always run her vocal mic (Stephen Paul-Neumann M 49) through the ELOP circuitry in my VoxBox, stereo piano (and sometimes bass) tracks through the digitally-controlled FET processors in my Amek 9098 rack; when mixing, I occasionally send the sax and violin though the VoxBox as well. The final mix always gets “homogenized” through my Manley VariMu.

With these sounds in mind, I set about to see how the SLAM! compared in similar circumstances. It’s not surprising that it did almost as well as the VoxBox on Sonya’s voice, although its sound was a little cleaner, and I missed the VoxBox’s Pultec-type EQ. But then, one mono VoxBox costs $4,000! I liked SLAM! better on bass and sax than the VoxBox. Piano and drum tracks sounded in the same ballpark as they did through the Amek 9098.

I was not as keen on the SLAM! as a stereo two-bus dynamic processor. In my book, nothing can touch Manley’s Variable Mu for imparting creaminess to a final mix. However, when I dialed out SLAM!’s opto effect, and concentrated on the FET limiter, I found its sound quite comparable to the Amek 9098 although the latter, of course, has more control parameters. Generally, I have never been able to use opto circuitry on mixes — whether classical or jazz, but I know other engineers who do. For tracking, however, the SLAM! has the best opto limiting I have ever heard.

Rock mixes were a different story. I have a great CD called R.I.M. 7, a course class project of my MTSU students from 1988, which Bill Kipper mastered for us at Masterdisk. We decided not to compress it, so it ended up sounding very good, but also quite low in level, compared with other CDs — especially today’s hypercompressed ones. So I thought I would try it through the SLAM! Wow! In about half an hour, I was able to make it much louder, and it still sounded great. I sure wish we’d had a SLAM! 15 years ago.

SLAM!’s digital option board features stereo converters with a unique topology. Codeveloped with a Swiss company, Anagram Technologies, its digital filtering circuitry is unique in that both data and clock are treated as a linked pair and processed via DSP with parallel algorithms. Its ADC samples at 192 kHz, and then downsamples to the desired lower rate; its DAC upsamples to 192 kHz. Although the SLAM!’s digital I/O can handle rates from 44.1 kHz to 96 kHz, its single XLRs make it physically impossible to do “dual-wire” 192 kHz, and “single-wire” 192 kHz does not exist.

So how do these converters sound? Smooth and warm. More in the direction of Apogee than, say, my Genex or Weiss gear. In fact, with the SLAM!’s transformer inputs and outputs, and Anagram’s “Quantum” circuitry, they actually sound cleaner than the converters in my Trak2, but still retain quite a bit of warmth. Of course, the SLAM!’s DAC is no match for my Weiss DAC1 Mk. II (which costs more than the entire SLAM!) or similar high-end boxes, but for $2,500 total, they are actually quite a bargain.

Although the optional DAC’s active balanced direct output sounded quite good, it is, in my opinion, not quite up to the level of the high-end separate converters that I use (some of them more expensive that the all-in-one SLAM!). I think the DAC sounds best after its audio passes through every SLAM! circuit – even when the limiters’ thresholds are set so that no limiting takes place. The SLAM!’s tubes-with-transformer-balanced output stage sounds large and warm – just the way I like it.


The SLAM! is the coolest high-end pro audio product I have seen and heard in a long time, and if I did not already own all that other gear, it would land at the top of my list. I miss only the presence of EQ, but since Manley Labs sells several separate high-quality EQ processors, there is an easy solution. Buy an analog SLAM! and patch in one of the various Manley EQ boxes. You will have a front end that will be hard to beat at any price.