Horizontal active monitors present a challenge solved with K+H bracket and The Stand from Blue Sky

Blue Sky’s The Stand with K+H O 300 mounting bracket (Figure 1)

The heavy and horizontal Klein + Hummel O 300 monitors need a sturdy monitor stand. At 30 lbs each and costing $5,000 a pair, you don’t want them dropping to the floor from 3 feet up.

This article is the second in a two-part about speaker stands and the K+H O 300. The first part provides details on Blue Sky’s The Stand.

When I got the monitors in 2009, Studio Economik suggested the Sound Anchors STUDADJR for monitor stands at $800 a pair.

I didn’t get a cheaper solution than Sound Anchors but I did get one that looks better and has more flexibility in speaker site. 

The monitors sit on the 10 x 14″ platform with Sound Anchors. I thought the 14 x 17″ base might allow lateral movement. Visions of bungee chords sprang in my head.

There is a bracket on the back of the K+H O 300’s that supports wall mounting but no one recommends that for near field monitors. Reflections off the wall would be too strong at the listening position and aiming them 30 degrees toward the mixing position a little tricky.

Neumann, who purchased, Klein and Hummel, has a detailed specification K+H Mounting Hardware Matrix with approved supports that include suspending from the ceiling or mounted on tripod and mono-pod stands from K+M.

Neumann recommend that loading stands with sand to dampen resonance does nothing. “We do not subscribe to all this “spike your stands” stuff seen in the hi-fi industry. A solid stand with this hardware is quite acceptable.” (Andrew Goldberg, Product Manager – Studio Monitor Systems, Georg Neumann GmbH)

Any solution from Neumann was going to cost about the same as the Sound Anchors and involved a confusing series of adapters.

Positioning the active monitors

K+H O 300 on meter bridge with Primeacoustics Recoil Stabilizer (Fig. 2)

I tried the K+H O 300s on OnStage SMS6000 Adjustable Studio Monitor Stands. It was scary to watch them sway in the breeze. (Fig. 3)

So I built a plywood meter bridge and placed the monitors on the extreme end of each side. (Fig. 2) That solution was certainly secure. The mixing desk can support 250 lbs. However,  there was no means to experiment with the monitor location to get the best sound in the room. Right off the bat monitors were about 1 foot too close together.

Position of the monitors side to side effects the proper stereo image at the mixing seat, just ahead of the focal point. They are supposed to be set up in an equilateral triangle with the listening position. The best distance is 67.5″ apart, according to some, which puts the focal point about 3 to 18″ behind your head.

Mixing desk with Mackie MCU Pro, the angled desk deflects reflected sound from the speakers. Note the O300s in the background on OnStage stands before the meter bridge (Fig. 3)

Monitors placed on the mixing desk or meter bridge transmit sound through the desk faster than through the air. The monitors are subject to low-frequency cancellation. That effect reduced by using the Primacoustic RX9 – HF Horizontal Recoil Stabilizer. (Fig. 2)

The other problem with meter bridge mounting is the sound reflects off the desk. The tapered angle of Mackie MCU Pro Control Surface, MCU Pro Extension and Mackie C4 Pro act like the traditional beveled mixing desk to deflect some of the reflections. (Fig. 3)

The recommended installation is the near field monitors installed on stands to get the best results.

Horizontal or vertical

K+H O300 Horizontal Directivity Plot (courtesy Georg Neumann GmbH / Sennheiser) click for larger image (Fig. 4)

Most active near-fields are placed vertically. The 3-way K+H O 300s are designed to mount horizontally with the tweeters to the outside.

Neumann give plenty of technical information in the K+H O 300 manual on frequency response and distortion both vertically and horizontally. The sweet spot for best response is narrower when mounted on the vertical. (Fig. 4)

The Stand and adaptation

Klein and Hummel LH-25 bracket (Fig. 5)

After a year of futzing with On-stage stands, the meter bridge and almost ordering the Sound Anchors, I came across Blue Sky’s The Stand. It had everything I needed – large 30 inch base for stability, capacity to handle 80 lbs, and vertical and horizontal adjustment. Blue Sky The Stand Review

To make the K+H O 300 secure, I ordered the Neumann LH-25 bracket specified in the K+H Mounting Hardware Matrix. (Fig. 5) From appearances it seemed like an easy adaptation to drill a few holes in the mounting bracket on The Stand and bolt them together.

Main bracket removed with thumb screw from Blue Sky’s The Stand (Fig. 6)

When the LH-25 and The Stand arrived, a simpler solution presented itself – remove the Blue Sky bracket (Fig. 6) and install the LH-25 bracket directly on the top of the chrome cylinder. (Fig. 7)

When I tested the adaptation, the thumb screw didn’t allow the K+H O 300 to pivot vertically. (Fig.  7 )

K+H O300 installed on The Stand with LH 25 and original thumbscrew limiting movement of O300 within the LH-25 bracket (Fig. 7)

Blue Sky confirmed, in an email, the thumb screw can be replaced with a 1/4″ bolt (coarse thread) and washer. I used a hardened 1/4″ x 3/4″ steel bolt, although the original thumbscrew is not hardened. (Fig. 8 )

Detail of 1/4″ bolt and washer securing LH 25 bracket to The Stand (Fig. 8)

Be careful not to over torque the 1/4″ bolt since it may either break or suffer shear damage and break later. Use only the amount of torque you would on the thumb screw.

You may wish to keep the original Blue Sky bracket and attach the LH 25 to it. It seemed redundant and merely added three more bolts to tighten and without adding any rigidity or features.

Installing the speaker

Detail – LH 25 thumb screw installs in side of K+H O 300 (Fig. 9)

The K+H O 300s come with a plastic screw in each side that must be removed first. If you take the speaker off the stand later, the plastic screws must be put back.

The hard plastic handled thumb screw and washers are installed as illustrated in Fig. 9.

This is a two-person job. One person can hold the 30 lb speaker and another can thread the supplied bolts, washer and rubber washers.

The biggest problem was holding the speaker in the correct place and not cross threading the screws.

Hand tighten the plastic covered bolts and no more.

Alternatively, one could place the K+H O 300 on its back, install the screws in the bracket and stand the assembly up.  That seemed a little dangerous so I got my daughters to help. (See Fig. 1 for fully assembled Stand, LH-25 and K+H O 300)

Alternate mounting brackets

If you pick a mono-pod or tripod stand for the K+H monitors, there are several other adapters available that will connect with them – LH 28, LH 29, LH 37 and LH 48. Consult the  K+H Mounting Hardware Matrix for details.

Putting the speaker and stand in place

This is again a two person operation. The whole thing is rather unwieldy with the base width, height and weight. The speaker stand will drop if you lift the from the speaker bracket, which is how you adjust the height up. (Fig. 10 )

Once in place, all that was need were small adjustments of the rubberized feet to compensate for the hard wood floor.

Installed – K+H O 300 mounted on Blue Sky The Stands using K+H LH 25 bracket (Fig. 10 )

Where to buy

Total cost was $600 for Blue Sky The Stand (pair) at Amazon.com or other dealers and $120 for the LH-25 brackets (pair).  Not many dealers carry the LH-25s but I did find a pair at Studio Economik who ship to the US and Canada. In Europe, Prosl.com will order them. Most Neumann dealers can order them from Sennheiser, who own Neumann, although several wouldn’t admit they could.

Dealers are listing these items as “Each” but you will need a pair of both. That must be to avoid sticker shock.

Klein and Hummel is a German manufacturer of professional studio monitors.  It bought by Georg Neumann GmbH, one of the world’s prestige manufacturers of studio professional microphones. Sennheiser, who acquired Neumann, is a well-known German manufacturer of headphones, microphones, public address, and other consumer electronics.

Blue Sky International,  an American company, makes a line of monitors for home, recording and project studios.