GR Research OB 5 - High Performance Speaker Kit Floorstanding Speakers

GR Research OB 5 - High Performance Speaker Kit Floorstanding Speakers 


High performance speaker building kit. It features a very fast, almost weightless, planar magnetic ribbon tweeter, crossed over at a low 1.8 khz.

Midrange is from 2-5.5", high speed woofer, in a boxless, open baffle, design. This offers a stunning, effortless, open mid range. Frequency range is from 220 hz to 1.8 khz.

Bass is from 2-5.5" high speed woofers, in a highly braced ported cabinet. This makes for very fast, detailed, and punchy bass.

The crossover uses all top quality parts used in costs no object designs. It is so well executed that the speaker is seamless.


Showing 1-2 of 2  
[Mar 24, 2008]
Audio Enthusiast


+ Really good 'voicing' by the engineers to yield a really exceptional speaker
+ Sweet spot encompasses almost all the area between the speakers
+ Quite efficient 91.2 db @ 1 watt-meter
+Small footprint
+Excellent parts throughout
+Can be played very loud with no distortion
+Can be used in either small or fairly large (> 20'x20') rooms
+Exceptional soundstage
+Excellent on all types of music: chamber, jazz, blues, soul, orchestral or country.
+Overall the best speaker that I've ever owned.
+Exceptional crossover


-Slightly harsh treble in certain passages. I'm not overly fond of the Behringer-Erlander planar tweeters, but these may 'smooth' over time. (I prefer the Vifa XT25GTs in my Madisound Odins.)

-Hard to fit the crossover. I would sugest building 'double decker' boards and position the largest coils on the upper deck. There would be plenty of room for all components in this design. (The second deck would have to fit through the opening in the lowest brace or this brace should be omitted.)

I purchased the kit form about eight months ago with the intention of finishing the project in a couple of months. I contracted with a local woodworker to build the cabinets and after eight months I had two beautiful, curly maple-veneer, Baltic birch OB-5 cabinets.

The x-overs are made with the finest components, Mills resistors, Sonicraft and Erse capacitors and huge, Alpha-Core inductors. The problems with the design is that the parts are so large it's very difficult to fit all the stuff into the small space allocated for it in the base compartment. I almost had a nervous breakdown figuring out how to piggy-back the capacitors and inductors (six/channel) to fit properly.

As it turns out you can now purchase a completed unit from Response Audio in Endicott, New York: and

Their introductory price is about +$200 over what it cost me to build the kit and you save the dust, stress,heartache and psoriasis of the build process, which GR-Research rates as 'novice' level of difficulty.

When I connected the speakers into my SS system, one of the speakers just emitted a hiss and the other played pretty well. Knowing the exactitude of my build, I swapped cables out and both started to sing. My amp as a left channel that is very sensitive to mediocre grounds.

System: Monarchy M24 - DAC/Pre
Cambridge Audio D450 CD player
XLO Reference and Better Cable Silver Serpents IC (with bullets)
Oval 12 Speaker Cable
Odyssey Stratos Dual Mono Amp
Poseidon Dynaco Mark II tube amps

Soundstage: Extremely wide and somewhat back, at the level of the speakers. The speakers disappear at times and vocals are disemobodied. It is definitely a 'you are there' experience, about 12-16 rows back in the concert hall.

Treble: Crystalline highs and well-balanced with the mids. Female voices can be a little harsh.

Mids: Palpable and detailed, excellent focus of voices and instruments. Easy to pick out individuals within groups.

Bass: Excellent, tight in mid-bass and good (but not great) control of lower bass. The bass only goes down to about 43 Hz, but what's there is unexpectedly good. The X-over will cut out overloads in the bass region. I tried a particulary demanding piece with cannons and organs in the cadenza and the x-over removed parts of the most demanding (<40Hz) finale.

Detail: Amazingly good in all ranges.

Imaging: Infinite baffle (dipole) design prevents pinpoint images. Instead, you get
a small area of where a sound is emanating from.

I estimate that it will require more than 100 hours for the break in period for these speakers and I've listened to them after the first 20, so my review may be unnecessarily hard.

I listened on both the 4 and 8 ohm taps on my Dynaco amp and prefered the 4 ohm by quite a bit. The speaker is nominally rated a 6 - ohm with dips to the 4 ohm at several points in the range.

Customer Service

Since I built this speaker, I would have to say the customer service was from above average to excellent.

Similar Products Used:

Madisound Odins, Von Schweikert VR4s, Speaker City ScanSpeaks, Klipsch Fortes

[Dec 06, 2006]
Audio Enthusiast


Stunning electrostatic clarity.

Completely vanish, opening up to a wonderful soundstage.

Mid range to die for.


Really good bass.

A true giant slayer in sheep's clothing.

Low price.

Tremendous satisfaction in helping to build a world class speaker.


Have to build a cabinet, or have build them for you.

Black Beauty Rides Again

And what a rii-iiii--iiiiiiiiiiii----de she gives.

Soaring beautiful highs.

Open mids.

Tight powerful bass.

All served up with electrostatic speed and clarity.

This speaker is very dynamic.

And talk about coherent. Brings back the warm fuzzies from my crossoverless Acoustat days.

Tonal balance is great. This is not some manic depressive speaker.

She has amazing detail, transparency, and clarity, yet those cone drivers add nice warmth. Probably the perfect blend of the two.

Yet it sounds seamless. I can not hear the crossover. It all sounds like one great big ribbon. Or more accurately, it sounds like real music.

Speakers completely vanish, leaving a wonderful soundstage.

These give me a very accurate portrayal of our recordings. and In fact they better the clarity of my Sen. HD 580s.


These are easily the best speakers I have owned. Here is the carnage. Acoustat model 3’s and 1+1’s, Apogees, Magnapans, Newform Research 645’s, Hornshopp Wannabees, Celestion SL2, Braun 1030’s, Angstrom Triads and T2’s, Triangle Celius.

I am still breaking these in, so I am going out on a limb, but here are my mental thoughts of the OB 5’s compared to some of the speakers I have had the privilege of hearing, or owning.

JM Labs Grand Utopia: Monsters with monster bass. Probably the best bass I have heard. Serious problems with tweeter smear, in that cymbals would trace back to the tweeter on occasion. Big, overpriced, and heavy. I did like them though. OB’s soundstage better, are more transparent, and still have great bass. I will take the OB’s and not blink an eye.

JM Labs Mezzo: Same as above.

Revel Salons: I really like these driven by Levinson gear. The OB 5’s are right in this category I believe. Salon bass goes lower perhaps, but I would say the OB’s have greater detail and clarity off the Neo 3 Ribbon. Both image well. OB wins on price and I bet sound as well.

Levinson HQD: Yes, the actual stacked Quad 57s, with Decca ribbon tweeter, and the 4 - 18” Hartly sub woofer monster. Well, this Goliath needs voltage limited amps for the quads, is huge and heavy, beams high frequencies so that an Acoustat model 2s seems like freedom. The OB’s only give up the fantastic bass of the heartly's. I’ll take the OB’s any day and leave the audio headaches for someone else.

Magnepan 1.6 and 3.6s: I like Maggies, always have. They demand space, at least 6’ behind them and a highly damped wall. They eat power for breakfast, lunch, and supper. This really limits amplifier choice. The OB 5’s sing on my Mcalister SE 44 -(22 watt) amp. They image better, with better focus. I like their bass better. They are more dynamic.

Triangle Celius: I don’t know how Stereophile made these a Class A speaker. While they have an exciting sound, albeit, by a tipped up response somewhere mid treble, they don’t present a very realistic acoustic space of live music. The Newforms killed them, and so do the OB’s.

Genisis Flagship, the 1’s I believe: I really liked these. While being super expensive, they also demand lots of space. The OB’s however give up nothing to them except ultimate dynamics and earthquake bass. Don’t get me wrong, the OB’s have great, powerful bass, but I am sure the line source Genisis would do better there. I will take the OB’s and be very happy.

Visitone B200: Heard briefly on open baffles, and not optimized. B200s sounded very nice for a single driver. Easy build for the DIY, but the OB 5 kills it. It simply cannot compete to the Neo 3 planer ribbon, or the powerful bass of the OB’s. Just my humble, but opinionated opinion.

I could go on and on.

I hope you are catching the drift here. When compared to some of the worlds most expensive, or highly regarded speakers, the OB’s really leave me wanting nothing.

I am almost speechless.

They are fantastic. And that is from a guy who says good when most would say great. Just conservative I guess.

The OB5 driven by the amazing McAlister SE 44 brings me to the very top shelf of audio on a pauper’s budget.

Thank you Danny for making such an overachieving wonder available to those of us with enough sense not to spend kilo bucks chasing the wind.

Danny was always a gentleman even though I probably drove him crazy with all my e-mails and calls.

Check out more at
and GR's website at

Bottom Line

I feel like I have arrived home after a long journey. I look forward to many blissful years with Black beauty.

This kit gets my highest recommendation.


Customer Service


Similar Products Used:

Acoustat models 1+1's, and III's.

NewForm Research 645.



Showing 1-2 of 2  

(C) Copyright 1996-2018. All Rights Reserved. and the ConsumerReview Network are business units of Invenda Corporation

Other Web Sites in the ConsumerReview Network: | | | |