Klark Teknik DN-405 (c. 1987)
One channel, five bands, and enough cut on tap to remove a room resonance without touching anything else.
Overview
The DN-405 is Klark Teknik's single-channel five-band full parametric equalizer. It belongs to the company's 400 series and was new to the range as of October 1987. Studio Sound (October 1987, p.46) caught it at launch, listing the DN 405 among the new 400 range of parametric equalisers and noting its five bands of full parametric EQ with separate high and low cut filters. Recording Engineer (October 1987, p.74) filed it in the same new-products column as a mono parametric EQ, next to the DN-410 two-channel parametric EQ. The two units were clearly conceived as a pair, one channel or two, same filter set.
A parametric differs from the graphic EQs Klark Teknik built its reputation on because nothing is fixed. The company's own manual puts it in plain terms: each of the five filters can be positioned at any centre frequency between 20Hz and 20kHz, with bandwidth variable from less than 1/12 octave to in excess of 2 octaves. A graphic gives you thirty faders at fixed ISO centres and whatever Q the designer chose. A parametric lets you put the notch exactly where the problem is and widen or narrow it until the fix sounds right rather than merely measures right.
The gain range is asymmetric, and on purpose. Each band offers 15dB of boost against 25dB of cut, so ten decibels more is available in the subtractive direction than the additive one. That tells you what Klark Teknik expected the unit to be used for. The manual is blunt about it, advising that needing large amounts of boost or cut within a curve probably means something is fundamentally wrong with the sound system or the room, and that the underlying fault should be investigated and corrected before final equalisation is applied. So the company built an equalizer and then told you not to lean on it.
The measured performance is quoted conservatively. Frequency response is held to ±1.5dB across 20Hz-20kHz, distortion at +4dBm stays below 0.01% at 1kHz, and equivalent input noise is better than -90dBm unweighted across the band with gain at +6dB. An overload indicator trips at +19dBu. None of those figures is spectacular alone. Together they describe a unit that stays out of the way.
Key Features
Five Fully Parametric Bands, 20Hz to 20kHz
Every one of the five filters is sweepable across the full audio band rather than restricted to a slice of it, so any band can go wherever the problem is. The manual notes that the five sections are designed free of interaction between each other. That means a multi-band curve is simply the sum of the individual responses. Stack three filters on the same region and you get what the maths says you should get, not a filter network fighting itself.
Variable Bandwidth from 1/12 Octave to Over 2 Octaves
The Q control is what makes the format worth the complexity. Narrow the bandwidth past 1/12 octave and the DN-405 works on a single ringing room mode. Open it beyond two octaves and the same band does broad tonal shaping. Most engineers end up using both within a single curve. The unit doesn't force a house voicing on you the way a fixed-Q graphic does.
15dB Boost Against 25dB Cut
The extra cut range is the practical detail. Feedback nodes and room modes usually need to come down far more than anything needs to go up, and 25dB of attenuation gives real authority over a problem frequency without a second unit. The 15dB of boost is ample for creative work, and the manual positions the 400 series for post-production, broadcast and studio use as readily as for sound reinforcement. The asymmetry also discourages the sort of heroic boosting that causes more problems than it solves.
Separate High and Low Pass Filters
Both the DN-405 and its two-channel sibling carry independent high and low frequency cut filters, with the high pass sweepable from 15Hz to 300Hz and the low pass from 2.5kHz to 30kHz, both at 12dB per octave. These are band-limiting tools rather than equalisation. Having them on dedicated controls leaves the five parametric bands free for other work.
Balanced Input, Floating Output, 1U Rack Format
The input is electronically balanced with a 20k impedance balanced and 10k unbalanced, on a 3-pin XLR. The output is unbalanced on XLR with a minimum load of 600 ohms, source impedance under 60 ohms, and a maximum level of +22dBm. The chassis is 482mm wide - a standard 19-inch rack unit - at 235mm deep and 44.5mm high, so a single rack space. Weight is listed at 3.5kg net, 6kg shipping. Power is a 3-pin CEE inlet, draw under 15VA, available in 110/120/220/240V at 50/60Hz. A relay delay circuit mutes the output for roughly two seconds at power-up, charging a capacitor until a transistor switches the relay on. When power drops, the same circuit kills the relay immediately. That saves a thump through the PA.
Historical Context
The 400 series arrived in late 1987 with the DN-405 as its mono parametric and the DN-410 as the two-channel version, the pair announced together in the trade press that October. Studio Sound (December 1987, p.9) ran an advertisement for the range aimed at engineers who had defined their problem precisely and wanted a correspondingly precise solution. The DN-405 stayed in the catalogue for years afterward: a UK dealer price list in Sound on Sound UK (May 1996, p.34) still showed it at £727, roughly nine years after launch. Production end dates aren't documented in the material available here.
Collectibility & Value
Prices are scattered and the market is thin. Used units have been listed in the $190-$250 range, a Japanese retailer has offered one at US$309 tax included, and a Russian listing appeared at 68,990 rubles. The 1996 UK dealer price of £727 gives some sense of where the unit sat when new. One eBay listing has surfaced titled "for repair," so non-working examples circulate. No specific fault is described, and there's no documented pattern of common failures or maintenance requirements in the sources gathered here. Buyers should assume a unit of this age needs a check-over rather than a restoration, and should verify condition directly since published information on typical faults is essentially absent.
Similar items on eBay
No exact Klark Teknik DN-405 listings are live right now — these searches show current Klark Teknik and similar vintage audio gear on eBay:
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.