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OB-7 Plus

We have discontinued OB-7 Plus because we no longer have inventory of the SA-1 power amps that went with this kit. As an alternative we recommend the standard OB-7 and an external sub, and Ideally one of our servo controlled subs.

The OB (Open Baffle) series of speakers feature mid-bass drivers mounted in an open baffle and covering ranges from 200Hz to 2kHz.

The driver complement uses the BG Neo 3 pdr covering the range from 1,800Hz and up. From there it hands off to a pair of M-130/16's mounted in an open baffle and covering from there down to a crossover point of 225Hz using a first order electrical slope. It then hands off to four M-130 woofers wired in a series parallel configuration. These are mounted in a sealed box and cover an area reaching down to a side loaded SW-12A 12" woofer. The SW-12A is also loaded into a sealed box at the bottom of the enclosure.

The open baffle area to the sides of the M-130/16 woofers are covered in grill cloth but can be left completely open.

These speakers have 91db sensitivity with 1 watt/1 meter and have about a 6 ohm average impedance load with a minimum impedance that drops to 4 ohms in the 4 to 5kHz range. The lower frequency range from 80Hz and down stays above 8 ohms. This makes them fairly easy to drive and easy to get good output levels without tons of power.

A small sub-woofer plate amp fits easily into the back of the enclosure and powers the 12" side loaded sub.

The separately powered sub makes the OB-7 Plus easy to integrate into any room. The output level of the bottom end can easily be adjusted to match the rest of the speaker regardless of the room size and low end room gain present from the room.

This also allows the end user the flexibility to crank up the bottom end or lower its output as desired.


How does it sound? These have been an absolute joy.

These speakers have an incredibly balanced sound from top to bottom with the real clincher being the mid-range area.

Vocals have a very open and unrestricted sound completely free of box colorations or loading effects on the cone from a rear enclosure.

The vocal region is extremenly smooth and easily draws you into the music.

Lower vocal range harmonics hand off to identical drivers with shallow slopes for a seamless transition.

Imaging is excellent with these speakers as they paint a very realistic picture of the presentation.

The top end is extremely detailed and has a very realistic sound to it, but is not overly hot, bright, or fatiguing. The Neo 3 pdr is crossed over to the mid-bass drivers at a fairly low crossover point compared to most speakers. This allows a level of speed and detail not matched by woofers typically used to cover this range.

With four of the M-130's covering the 225Hz range and down, the demand on the woofers is kept low and so is distortion.

The bottom end of these speakers is clean and extended with a -3db down point in the mid 20's. This allows the OB-7 to be a full range speaker that is very capable of covering anything one can throw at it and do so in an impressive way.

What comes in the kit? Everything!

Everything is now in stock and ready to ship. Crossover components include Erse XQ inductors for everything except the low pass on the four M-130 woofers. It uses a laminated Erse Super Q coil. Caps are a combination of Erse poly caps and Sonicaps. The larger Erse caps are all by-passed with Gen.2 Sonicap by-pass caps. Resistors are Mills and Lynk. These now come with the new patent pending Electra Tube Connectors. Included are eight, good looking, solid Brass floor spikes. The standard internal wire is a high purity solid core 16 gauge with a polyethylene jacket.Screws, solder, and heat shrink are also included.

The Electra Tube Connectors have a $59 a set retail value.

This kit now includes the SA-1 amp. Read about this amp here:

For reference, our A/V series kits and enclosures are considered entry level to novice level in difficulty. The OB-7 Plus kit and enclosures would be considered to be on a novice to advance level in difficulty.

For this build we recommend 4 sheets of No Rez.

Prices are per pair. Click here for enclosure plans.


Your Price: $1,495.00
Item Number: OB-7 Plus
Manufacturer: GR Research
Manufacturer Part No: OB-7 Plus


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