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NEUMANN KH310 TEST REPORTSSOUND & RECORDING 04/13

Test: Neumann KH 310Near-field monitor

1 TEST REPORTS NEUMANN KH310 SOUND & RECORDING 04/13

With the KH 120, the traditional microphone manufacturer Neumann succeeded in making a brilliant debut in the near-field studio monitor

market segment. Within a short time the small monitor was at the top of the sales charts – justifiably so, due to the sound characteristics and

the unbeatably good price/performance ratio. This was ample reason to be curious about how the new 3-way system would fare in our measu-

rement and testing studio.

Neumann KH 3103-Way High-End Monitor Tested & Measured

AUTHOR: DR. ANSELM GOERTZ, FOTOS: DIETER STORK, DR. ANSELM GOERTZ

NEUMANN KH310 TEST REPORTS 2

With the KH 310, Neumann Berlin isnow presenting the second newly deve-loped monitor since the takeover of theKlein+Hummel brand under the Neu-mann label. The KH 310 is a compact 3-way system for near-field and mid-fieldapplications, which is also well-suitedfor use as a surround monitor in largerstudios. In contrast to the approach ofmany other manufacturers, the externalappearance continues to be very incon-spicuous, and has scarcely changed incomparison to the previous model O300. However, when examined closely,the KH 310 is revealed as a completelynewly developed system with manytechnical fine points. Only the conceptremains unchanged: 3-way with a seal-ed housing, with the external shapeand dimensions of the housing remai-ning the same. All of the drivers, the

entire electronics and the driver wave-guides are newly developed.

EXTERNALS

The KH 310 now continues the conceptof the O 98 (1982-1998), O 198 (1998-2000) and O 300 (1999-2013) into thefourth generation. Thanks to its closelyarranged loudspeakers and the resul-ting small front surface area, the appli-cation possibilities of the compact 3-way system include use as a large near-field monitor, or as a main or surroundloudspeaker. Due to its low height, theKH 310 hinders neither the acoustics ofmain monitors located behind it, northe view through the control roomwindow.

The midrange and tweeter arefavorably situated one above the other.For the woofer positioned to one side,

the “side-by-side” arrangement is lessproblematic, because the crossover at650 Hz occurs at such a long wave-length that the distance between thedrivers no longer has an adverse effect.

Particularly for compact monitors,sealed housings are rather rare. Thereason for this is the greater level stabi-lity of bass reflex designs, which exhibithigher sensitivity at low frequencies,thanks to the support of the bass reflexresonator. However, such designs havetwo disadvantages. Not only does thefrequency response below the resonan-ce tuning frequency of the housingdiminish twice as sharply (24 dB/oct.)as that of a sealed housing (12 dB/oct.),but also the phase shifts, of 360° inste-ad of 180° through the high-pass functi-on, are twice as great. This means thatapart from the achievable bass level, a

SOUND & RECORDING 04/13

THE FREQUENCY RESPONSE IS ONE OF THE BEST EVER

MEASURED IN OUR TESTING LABORATORY.

+++Measurements

+++Sound quality

++Possible applications

+++Workmanship and value

+++Price/performance ratio

Manufacturer/Model Manufacturer/Sales Neumann / Sennheiser

MSRP per pair: 3,994 euros r www.neumann.com

3 TEST REPORTS NEUMANN KH310 SOUND & RECORDING 04/13

The following measurements of frequency response, directivity and distortion values come from the measurement

laboratory, with anechoic conditions. The class 1 measurement chamber permits measurement distances of up to 8 m, and provides free-field

conditions for the range of 100 Hz upward. All measurements are performed via a B&K 1/4" 4939 measurement microphone with a 96 kHz sam-

pling rate and 24 bit resolution, with the aid of the Monkey Forest audio measuring system. Measurements below 100 Hz are performed as com-

bined near-field/far-field measurements.

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NEUMANN KH310 TEST REPORTS 4SOUND & RECORDING 04/13

sealed housing is in fact a better choice.The bass level is precisely what makes abass reflex housing indispensable as arule, especially for small monitors, sin-ce even at low frequencies a certainminimum level is essential for listeningunder usual level conditions. However,with an 8" woofer, the size of the KH310 is such that even without the sup-port of a resonator a high level can beachieved, which is thus primarilydependent upon the capabilities of thedriver.

This design was developed comple-tely by Neumann itself, from the simu-lation, to all of the series of measure-ments, to the tools. Special attentionhas been paid to the large linear excur-sion. With sufficient amplifier power,here ensured by a 210 W peak for thewoofer, the desired sound pressure levelcan thus also be attained with a sealedhousing. Even the two domes havebeen developed completely by Neu-mann and, like the woofer, are manu-factured exclusively for Neumann asOEM parts.

Above a certain frequency, a domeno longer oscillates as a unit, butbegins to develop independent break-up modes, where particular zones of thediaphragm form local oscillation pat-terns. Figures 8 and 9 show images ofthe midrange and tweeter domes obtai-ned via laser interferometer scanning.Here the differences can be clearly seen.For the tweeter, the goal is to shift thebreak-up modes as much as possible tothe range above 20 kHz. For the large 3"midrange diaphragm of course this isnot possible, but here it is also notrequired, since the midrange is drivenonly up to 2 kHz, where it operates wit-hout any problem, as shown in Figure 8.

The large midrange dome, like thetweeter, is equipped with a waveguide,which controls the directivity and alsoprovides for an increase in sensitivity,thus combining two advantages. Forthe midrange, due to the compactarrangement at the front, the wavegui-de is of necessity rather small. The gainin sensitivity is therefore alsosomewhat secondary. Nevertheless thecurves, as well as the bulge around thewoofer, result in less reflection interfe-rence for the other drivers.

01 It could scarcely be better: On-axis frequencyresponse measured at a distance of 2 m. At the topare the filter curves for the treble, low-mid and bassfilters (blue, orange and green, respectively). The twogray lines indicate the frequency range from 100 Hzto 10 kHz, for the evaluation of ripples. The curve(violet line) extends from 30 Hz to 22 kHz (-6 dB),with an almost vanishingly small ripple of only 2.2 dB(maximum to minimum).

02 On-axis phase response measured at a distance of2 m. At the crossover frequencies of 650 Hz and 2 kHzin each case there is a 360° phase rotation. At thelower end of the transmission range there is anotherrotation of 270° due to the electronic 1st order high-pass filter and the acoustic 2nd order high-pass filter(sealed housing).

03 Maximum SPL at a distance of 1 m, at maximum3% distortion (red curve), and maximum 10% distor-tion (blue curve) for the bass range up to 300 Hz.Below 100 Hz the woofer averages 104 dB, and bet-ween 100 Hz and 10 kHz the average maximum SPLappears as 111.7 dB. There are no weak points at allin the form of sharp drops in the Max. SPL curve.

04 Spectrogram of the KH 310, with perfect decayfree of resonances.

05 Horizontal directivity represented by isobars. At the transition from yellow to light green, the leveldropped by 6 dB relative to the center axis.

06 Vertical directivity with a slight constriction at thetransition point between the midrange and tweeter at2 kHz.

07 Measurement of intermodulation distortion withan EIA-426B spectrum multi-sine signal having a 12 dB crest factor, for 85 dBA Leq at distances of 2 m(red curve) and 4 m (blue curve). Here the red curvefor measurement at a distance of 2 m likewise provi-des optimal values, with distortion considerably below-30 dB (3%). If the level is increased by 6 dB (85 dBAat 4 m), the intermodulation distortion in the range ofthe woofer below 600 Hz then increases by approxi-mately 10 dB, but still remains below -20 dB (10%).

08 Oscillation behavior of the Neumann midrangedome at 2 kHz (left), compared to that of a dome ofsimilar size of another manufacturer (right).

09 Oscillation behavior of the Neumann tweeterdome at 15 kHz (left), compared to that of a dome ofsimilar size of another manufacturer (right).

10 Averaged frequency response measurement foreach of 30 positions of the left and right loudspeakeraround the listening position (blue). Below 150 Hz,the room modes are clearly evident. An EQ (green) forthe room correction was derived from the measure-ments. At the bottom is the averaged curve with EQ(red).

NEUMANN KH 310 PROFILE

Frequency range: 30 Hz - 22 kHz (-6 dB)

Ripple: 2.2 dB (100 Hz - 10 kHz)

Horizontal opening angle:

112° (-6 dB isobar 1 kHz - 10 kHz)

Horizontal standard deviation:

19° (-6 dB isobar 1 kHz - 10 kHz)

Vertical opening angle:

82° (-6 dB isobar 1 kHz - 10 kHz)

Vertical standard deviation:

24° (-6 dB isobar 1 kHz - 10 kHz)

Max. SPL:

111.7 dB (3% THD 100 Hz - 10 kHz)

Bass capability:

104 dB (10% THD 50 - 100 Hz)

Max. SPL at 1 m (free-field) with EIA-426B signal at

full-scale level:

102.4 dBA Leq and 116 dB peak

Pair deviation:

0.45 dB (max. value 100 Hz - 10 kHz)

Noise level (A-weighted): 16.5 dBA (distance 10 cm)

Dimensions: 383 x 253 x 292 mm (WxHxD)

Weight: 13 kg

ELECTRONICS

The electronics of the KH 310 are allfound at the rear panel, which is manu-factured in one piece from a section ofcontinuously cast aluminum. Inside arethe circuit boards for the power supply,the amplifiers and the filters. The num-ber of cables is kept to a minimum,with the result that the entire installati-on, even with cables, makes an orderly,tidy impression. For the power supply, a modern HF switched-mode powersupply was selected. The amplifiers areintegrated class AB circuits with150/70/70 W continuous and210/90/90 W peak output power. Cros-sover is effected by 4th order filters (24 dB/oct.) at 650 Hz and 2 kHz.

5 TEST REPORTS NEUMANN KH310

At Neumann nothing is left to chan-ce. For users, this can be seen in vario-us aspects, e.g. very practically in theinstructions, which truly deserve thename, or – not so immediately appa-rent, but nevertheless important – inthe heat dissipation via the rear panel.Developer Markus Wolff illustrated thiswith a thermogram (Fig. 12) of the rearpanel of the KH 310; the temperaturedistribution shows the uniform heatingof the heat sink, with no hotspots thatcould be dangerous for the compo-nents. At the same time, the temperatu-re of all of the control areas is conside-rably lower.

The limiters have also been develo-ped with great attention to detail. Thereis an independent thermo limiter foreach driver, with a long time constant,as well as peak and excursion limitersfor the woofer. As soon as one of the li-miters is active, the Neumann logo onthe front of the monitor flashes red.

All of the controls are found on therear panel, in the form of reliable sli-ding switches. Once one is familiar withthe function of the switches, the set-tings can be quickly recognized by rea-ching behind the monitor. In the“Acoustical Controls” area there are fil-ters for the bass, low-mid and treble,

each with four settings. The effect ofthe filters is demonstrated by the green,orange and blue curves in Figure 1. Anadditional switch marked “Output Le-vel” has the four settings 94, 100, 108and 114 dB, for the sound pressure levelreached with an input voltage of 0 dBuat a distance of 1 m. Beside it is a trim-mer, in case intermediate settings aredesired. There are also controls for thebrightness of the logo on the front ofthe monitor, and for the ground lift.

SOUND & RECORDING 04/13

In addition to the usual exterior photos taken in the test laboratory, details and the interior of the monitor were also brought to light

via the camera. Opening the rear panel reveals the complex electronics. In the background the housing made of MDF can be seen, with many co-

vered cables.

11 Perfectionism is also appa-rent from the back, with a rearpanel made of a section of con-tinuously cast aluminum. All ofthe switches are well-arrangedand clearly labeled.

12 Nothing is left to chance.Thermogram of the rear panel,demonstrating a uniform distri-bution of heat over the heatsink.

13 The electronics inside therear panel, with a switched-mode power supply and fouramplifier integrated circuits on the aluminum section.

14 The three drivers seen fromthe rear. The woofer and twee-ter are equipped with ferritemagnets, including compensati-on magnets. The midrange isprovided with a neodymiummagnet.

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NEUMANN KH310 TEST REPORTS 6

LISTENING TEST

The listening test took place underwell-known conditions, and also invol-ved several other loudspeakers, whichwere all installed and tested in sequen-ce. As expected, the KH 310 proved tobe completely neutral and comprehen-sive. Nothing was lacking, at either thelower or upper end. At a listening dis-tance of 2.5 m, even with difficult material, the impression that the KH310 had reached its limits never arose.This is probably one of the most obvio-us advances achieved in comparison tothe previous model O 300. The diffe-rences with regard to the other systemstested in the same session were clearlyidentifiable, in favor of the KH 310.

Nevertheless, the results weregenuinely interesting in terms of manydetails often noticeable only at thesecond hearing, e.g. the depth differen-tiation of sources in the recording. Alt-hough with other loudspeakers theselay more or less in the plane of theloudspeaker, the KH 310 succeeded inreproducing clear depth differentiation.Over time one thus detected variousother details that had not previouslybeen heard. However, despite all theprecision of the reproduction, this wasnever at the expense of enjoyment orthe reproduction dynamics, and thisheld true independently of the type ofmusic material being monitored.

MEASUREMENTS

In the fine tradition of the earlier moni-tors, for the KH 310 one expects excel-lent measurement results that requireno discussion. The frequency response(Fig. 1) is one of the best ever measuredin our testing laboratory. Above 20 kHzthe curve then drops sharply, since thisis the range of the tweeter dome dia-phragm resonance, the excitation ofwhich is to be avoided. This is effective-ly suppressed via a special circuitdesign for the tweeter control.

Basically, one could be of the opini-on that in fact no more signal compo-nents are to be expected here. Never-theless, if such components occur, e.g.in the case of 96 kHz recordings, then astrong excitation of the diaphragm

resonance via intermodulation distorti-ons would be perceptible even in theaudible frequency range, and this isprecisely what is to be avoided.

In the spectrogram shown in Figure4, the KH 310 proves to be extremelyimpressive. The decay behavior is per-fect in every respect. The promiseshown by the special woofer design andby the oscillation behavior illustratedin the images of the two domes hasthus been fulfilled.

In terms of the maximum SPL andthe intermodulation distortion, illustra-ted in Figures 3 and 7 respectively, heretoo the KH 310 exhibits excellentresults. For the midrange and tweeterthe values increase only minimally,demonstrating one of the advantages ofthe 3-way system. If the woofer receivesstrong inputs and large excursions aregenerated, the accompanying intermo-dulation distortions are restricted to asmall, uncritical frequency range incomparison to the situation with a 2-way system.

If the KH 310 is operated close tothe level where the limiter takes effect,then at a distance of 1 m, an averagelevel LAeq of 102.4 dBA and a peaklevel LZpk of 116 dB are achieved. All ofthe data were measured for an indivi-dual speaker.

With regard to directivity, the KH310 has two advantages which comeinto play. One is the extensive tweeterwaveguide, and the other is the 3-wayprinciple, where the midrange does nothave to be reproduced by the largewoofer diaphragm. In large areas, therelationship of the “diaphragm diame-ter to wavelength transmitted” thus hasa more favorable ratio than is the casewith a 2-way system. The horizontalisobars in Figure 5 appear correspon-dingly uniform, with an average ope-ning angle of 112° and a deviation ofonly 19°. The vertical isobars are natu-rally somewhat poorer, but still verygood. Here the average opening angleis 82° and the deviation is 24°. Thesmaller vertical dispersion angle here is intended to reduce reflection interfe-rence from the ceiling and work surfa-ces.

Two additional measurementsshould be mentioned. The noise level of

16.5 dBA at a distance of 10 cm is at anexceedingly low level, which is imper-ceptible at normal listening distances,and the pair deviation of only 0.45 dBis extremely low.

CONCLUSION

As a near- to mid-field monitor, the KH310 r from Neumann displays the samealmost obsessive perfectionism which isalready familiar from the KH 120. Theworkmanship, measurements, and liste-ning impression are all completely con-vincing throughout, all of which hasbeen accomplished without the use ofany exotic concepts, transformers orthe like. With straightforward enginee-ring skill, here a highly professionaltool of the highest quality has beencreated.

Anyone who now thinks that thismay all be fine and good, but certainlysounds boring and will not provide anylistening pleasure, is greatly mistaken.A listening trial at Neumann Berlin or adealer can quickly dispel this impressi-on. Possibly one may then be 4,000euros poorer, however with the goodfeeling of having made a safe andworthwhile investment. n

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