Fredenstein Preamplifier & Compressor

These neat little modules offer far better performance than you’d expect at this price. Is there anything not to like?

Fredenstein are a Taiwan–based manufacturer, with a diverse range of pro–audio products designed by a team of German and American engineers. The current product line–up includes preamps, compressors and equalisers, in both rackmounting and API 500–series modular forms, and with valve, solid–state and even DSP technologies in various models. An additional interesting aspect of the company’s design strategy is to avoid negative feedback as far as possible, using intrinsically linear circuits that don’t rely on corrective feedback — an approach which they claim brings sonic benefits.

The Artistic Series, described as the company’s ‘value line’, aims to balance ‘top of the line’ performance with very affordable prices — the range costs roughly a third of the equivalent products in Fredenstein’s F600 range. The Artistic range currently comprises just two 500–series modules: a FET compressor, and a preamp. For the review, these two units were installed in the company’s own Bento 2 rack unit, which occupies 1U of rack space, accepts two sideways–mounted 500–series modules, and has an integrated power supply.

Bento

The Bento 2 is constructed from black–painted steel and extends 80mm behind the rack ears. Its internal universal power supply accepts 90 to 240 V AC mains (so there’s no big mains transformer to couple hum into mic preamp transformers). The audio connectivity comprises both XLR and parallel–wired TRS sockets for the two module inputs and outputs, and a pair of recessed toggle switches on the rear panel provides linking options. The top switch connects the output of slot 1 directly to the input of slot 2 (and disables Slot 2’s rear–panel input connectors), while the lower switch connects together the two slot compressor side–chain terminals (pin 6 of the chassis connector) to allow stereo–linked operation when two compressor modules are installed.

It’s all very straightforward, really, and the only slightly odd aspect is that there are two power switches, one integrated with the IEC inlet, and another on the right–hand side of the front panel, alongside LED indicators for the three power rails (±16 and +48 V DC). The Bento range also includes a portable lunchbox–style six–module chassis, and a larger rackmounting 10–module chassis.

Preamp

The Artistic Mic Preamp is also a very straightforward design, featuring an electronically balanced mic input via the host chassis’s connectors and a front–panel Direct Input socket (100kΩ input impedance). The mic input is automatically disconnected when an instrument plug is inserted. The primary gain stage is courtesy of the company’s OPA2 discrete op amp block (using SMD technology), which is pin–compatible with the likes of the API 2520 and Jensen 990 designs, allowing substitution, if desired. An American steel–core output transformer is also employed.

The white legends are very readable on the black painted panel, and everything feels solid and reliable. An eight–LED output level meter commands the top of the control panel, with a rotary gain knob and four illuminated push–buttons below. The phantom–power button light is red, the Low Z one green (changing the mic input impedance from 1500 to 300 Ω), a –20dB Pad yellow (this is only effective on the mic input, not the instrument input), and output polarity reverse is blue. The available gain range spans a nominal 15 to 65 dB, and the control scale suggests reasonable uniformity with rotation. The bar–graph meter covers a usefully wide dynamic range from –30 to +20 dBu, with five green LEDs (–30, –20, –10, –5 and 0 dBu), followed by two yellows (+5 and +10 dBu) and a red (+20dBu).

In use, Fredenstein’s Artistic preamp has a respectably low noise floor at all gain settings, with a tonally well–balanced and very open sound character. I felt it also exhibits a slightly mid-range–rich and larger–than–life quality, and the sound is definitely musical and involving. I might even say pleasingly ‘analogue’ — it certainly could not be called sterile! There’s plenty of gain available for all normal purposes, and the pad option ensures very loud sources and sensitive microphones can be accommodated without issue.

However, I found that the instrument input lacked headroom; a maximum input level of +5dBu just isn’t enough and can be reached easily by electric guitars with hot pickups, let alone active sources like keyboards and synths. Had the pad been available for the DI source this wouldn’t have been an issue, but as it stands I think the preamp’s gain structure would benefit from some re–assessment (and no one will ever need 65dB of gain on an instrument input!).

Of considerably less significance, but a niggle all the same, I found the bar–graph meter accuracy was a little frustrating as it consistently under–read by about 2dB. Overall, though, the Artistic Mic Preamp is a good-quality, very musical–sounding preamp that represents excellent value for money and boasts some tweaking possibilities.

Compressor

The matching Artistic compressor module has a busier front panel, with five knobs, four toggle switches and a 13–LED gain reduction meter. Internally, the compressor uses the same OPA2 gain-stage block and output transformer. The rest of the circuitry uses surface-mount devices. The active gain–reduction element is a FET, apparently used in a proprietary ‘reverse–Mancini’ architecture, although I’m embarrassed to say I have no idea what that might be!

The Bento 2 500–series chassis features balanced I/O on both XLR and TRS jacks, as well as compressor–link and module–routing switches.

In effect, the unit operates with a fixed internal threshold (apparently set at +5.5dBu), so the amount of compression is determined by adjusting the input level control. The control knobs are all potentiometers (there are no rotary switches), setting the input level (–10 to +20 dB), compression ratio (2:1 to 20:1), release time (70ms to 2.5 seconds), output level (0 to +20 dB), and mix (wet/dry), the last allowing parallel compression with the module itself. The four toggles introduce a side–chain high–pass filter (off, 150Hz, 300Hz), side–chain linking with adjacent rack modules, adjust the attack time (0.5, 2.5 or 5 ms), and provide on/bypass switching. The meter always shows gain reduction, in single-decibel increments up to 8dB (green), followed by 2dB steps to 16dB (yellow). The red clip LED operates at 24dB.

FET compressors are generally very flexible devices, with a good dynamic range and fast, efficient gain reduction. The Artistic compressor does all that’s expected of it, with the ability to provide moderate levels of gain reduction surprisingly transparently for such a modestly priced unit. It can also introduce some welcome attitude to the sound with higher ratios and shorter attack and release times. Again, this is a very cost–effective product performing at a much higher level than might initially be expected, and it delivered very credible results on a range of bass, vocal, and snare drum processing,as well as spoken word. The built–in dry/wet mix control enables instant parallel, with all the associated transient benefits.

Bench Tests

My bench tests, using an Audio Precision test system, revealed that the preamp’s minimum gain is actually 21dB (not 15dB), and the maximum is 63dB, but all apart from the lowest gain–scale markings proved reasonably accurate, and the gain–bunching at the top end of the control that’s exhibited by so many budget preamps is pleasingly absent here. The bar–graph meter LEDs generally illuminated about 2dB higher than the corresponding scale marking.

The Artistic FET Compressor features controls you’d not expect to find on such an affordable unit: there’s a wet/dry blend control for parallel compression, a side–chain high–pass filter and a module–link facility, for example.

The overall frequency response remained commendably uniform at all gain settings, and the –3dB bandwidth extends between about 5Hz and 60kHz. There is a very modest LF ‘bloom’ of about +2dB centred at 15Hz, probably related to the steel–cored output transformer. The output impedance is 600Ω and when loaded with a 600Ω termination the output level falls by nearly 6dB, but the frequency response is barely changed. The mic-input circuitry is transformerless, and uses a discrete transistor gain stage.

Noise and distortion (THD+N) measured below 0.02 percent with a maximum gain setting and an output level of +4dBu. It increased steadily to 0.04 percent by the time the red bar–graph meter LED had illuminated, while at lower gains the THD+N figure remained below 0.01 percent. The odd and even harmonic distortion components were fairly evenly balanced up until the onset of clipping, when the third harmonic became dominant.

The maximum output level is +26dBu, and the maximum mic input level (without the pad engaged) is +4dBu, rising to +24dBu with the pad switched in. The maximum instrument input level is a little low at just +5dBu, and the pad is not available.

The compressor module also boasts a very flat frequency response, extending between 6Hz and in excess of 80kHz at the –3dB points. As the amount of gain reduction increases a wide and moderate 2dB dip is evident in the response, centred around 100Hz. It is audible, tonally, but is generally often complementary to the effect, reducing mid–range muddiness usefully.

With no compression, I measured THD at 0.05 percent, in line with the published specs. Output noise (without gain reduction or make-up gain) was –72dBu, which is higher than I expected (the handbook claims –90dB but doesn’t state the reference). Maximum input and output levels are a healthy +26dBu.

Conclusion

Overall, I am very impressed with these Fredenstein Artistic Series modules. They both deliver very competent and credible performances (technically and musically) that are directly comparable with many far more expensive 500–series modules from leading manufacturers. Of course, some specialist high–end modules might provide more character, better specifications, or more flexibility, but for general everyday studio applications I found these Artistic modules to be extremely effective musical tools, and nothing about either of them made me want to reach for something ‘better’ — they both proved more than capable of handling all I threw at them, and delivered excellent results. At these kinds of prices and quality levels, they even make DIY modules look expensive, and yet there’s still the opportunity to tinker with the main gain stage by swapping it for other DIY or commercial discrete op amp modules. Highly recommended.