Pure Audio Project open baffle speakers


Has anyone out there tried these?

They sound intriguing 

Are there any/many got-ya's like room size, speaker placement in room, amp size/type etc...

A friend tried DIY open baffle a couple of years ago and they were quite large

My problem at the time was the amount of space I had available. I have since moved into a new house with a much larger listening area - 17' x 42' with 8 ft ceiling

Thanks for any input - Cheers

I have heard them and they are very developed product.  I heard the trio twice and if you have the cash go for it.
I've heard them in several settings.  If interested in open baffle, lean toward Spatial.
OB speaker enthusiasts comprise a large segment of the DIY speaker community. There is lots of info available about OB design on the GR Research AudioCircle Forum. 
You need to know what your goal is. Otherwise you are just going down the rabbit hole. 
I agree with the spatial recommendation. A fair comparison to the PAP would be the X series.


Emerald Physics Open Baffle have won many awards. My 3 years experience with their KCIIs (with WireWorld and Clarity Cap upgrades) is joyful. At under 48" tall they blow away my Magnepan 3.5Rs (6ft+) and are a very easy load to drive @ 95 dB+: MSRP < $2000. EP has a number of other models in this line. Since my room is a good bit bigger than most, I am in high anticipation of receiving the 2.8s with 2 @ 15" carbon fiber woofers and 12" concentric carbon fiber midranges per side MSRP $9999, includes shipping
I'm sure they go very loud which is impressive but it does not mean the sound quality is good. In their favor is that the woofers become very directional along with the horn which is directional. This would limit room interaction nicely. The cross over point here is critical. They have to keep that horn out of trouble but you want to get away from those woofers as soon as you can. The very low bass is going to be very confused. I would cross over to a sealed sub at 100 Hz.
@mijostyn - your statement about very low bass - are you thinking about "LFE style" low bass (below 20 Hz) or the bass produced by stringed instruments e.g. low A on a concert piano is around 27 Hz.

The very low bass is going to be very confused. I would cross over to a sealed sub at 100 Hz.

I seriously doubt that. My X3s go reach down to 25 hz with authority. The bass is very controlled and pitch correct. OB bass is probably about the most natural reproduction of the lower frequencies you are likely to hear, along with horn loaded bass. Both can be exceptional.


@acresverde  Thanks for the help. I guess there is of course more than one Ozzy, as I would like to be named Ozzy as well. Just not the bat-eating one.
Also check out  Tri-Art Audio.  I have a pair of 5 Open's coming my way soon.  Funky bamboo wood.  Great dealing with this Canadian company.
I have read many comparisons with Spatial and Pure Audio Project.
Many like the Tri-Art speakers better.  Check out a review from Dagogo. the reviewer compares the PAP speaker and Tri-Art.  Tri-Art is less expensive also. 
I was interested in open baffle myself, thinking about the PAP, then I found a set of Emerald Physic 4.8s at less than a third their normal price on Audiogon and bought them. Should get them in a few days, also orders a Rhytmik servo sub to go with them. GR research has an intresting speaker Dannynis working on called Line Force. Seems he’s waiting on one element of the design, one of the drivers that I guess he was happy with the initial ones, before he offers it. New Record Day was describing the sound when they ineterviewed Danny at his place, and once they come out I’d like to try those along with his OB triple bass subs.
I highly recommend checking out Danny Ritchie's (GR-Research) Youtube channel which has a lot of great information about open baffle speakers. 

I am currently using GR Research's NX-Otica speakers and stereo triple OB servo subs. I'm loving these speakers - truly full range, dynamic, and deep, airy sound stage - but I'm also lusting after Danny's Line Force speakers. When he's able to get the Neo10's produced, I'll be in line (excuse the pun) to order a pair.
Thanks for everybody’s input - there are certainly a few options to think about and investigate

@kenjit wrote...
You need to know what your goal is. Otherwise you are just going down the rabbit hole.
Agreed - as I said - I had a friend who tried OB designs and he spent a lot of time (down various rabbit holes) pursuing options.

My goal - to find a speaker that offers the most lifelike performance.

However, I’m not into DIY when it comes to speakers and as such I would prefer assembled units.

But I do need to listen to OB models again, to confirm they have something more than what my current speakers offer.

Previous OB models I had listened too lacked bass, but excelled in high/mid range and imaging. Several Models mentioned here sound as though they might fit my requirements from the reviews I have read..

Whilst my listening space is now much larger than before, size is still a significant consideration.

Again - many thanks for all the input - much appreciated - Steve

Might want to watch the almost 1.5 Hour interview with Clayton Shaw/Spatial on youtube that aired just yesterday. Go to the NEW RECORD DAY channel.  Your assumption on lack of Bass couldn't be any further from the truth in his designs...and I prefer a Lack of Bass presentation. He explains the whole process of room interaction with Open Baffle speakers compared to Box speakers. If nothing else you'll learn how these work and if you think they are a good match for your needs.
Williwonka, I am thinking about wavelengths, 100 Hz being about 10 feet.
As you get to the bottom of a drivers response curve it becomes more and more omnidirectional or conversely as you go up the frequency response curve the driver becomes more directional. The most important factor here is the size of the driver. As the woofer goes down it's response curve the front wave cancels out the back wave. When you put the driver in a baffle board you can separate the front wave from the back wave down to a certain frequency depending on the size of the baffle. How is a 24 inch baffle board going to separate wavelengths over two feet? It can't. In open air you get a predictable situation with the response curve falling off as the wavelength exceeds the size of the baffle board. In a room the situation becomes very complex and unpredictable with waves bouncing off walls and interacting with each other in very complex ways. The result is very unpredictable response in the bass, an unhappy situation. I can only guess but I think this passes with many people because they have not ever heard a system that goes flat down to 18 Hz.
This is not easy to achieve. Many very expensive systems do not do bass well and in many instances it is not the system but the room. You can easily get 10 dB aberrations in response in your average listening room. 
With an unbaffled  driver this situation just gets worse. 
Some people deal with this using a "swarm" system where they randomly place multiple drivers throughout the room. I deal with it by using a bass linear array and room control. You could never manage an unbaffled subwoofer system with room control. It is impossible to increase the volume of a frequency that is desperately trying to cancel itself. The response has to be +- 5 dB for room control to work well.  
You have no clue until you hear OB bass done right. And Spatial gets it right. You can speculate all you like, but that's all you are doing.


There is a company that builds cabinets and puts together speakers using Danny’s parts. I have emailed him a few days ago myself, but have yet to hear from him
I forgot to mention, I use full range ESLs so I am handily in the open baffle club. At higher frequencies it turns out to be an advantage in your average room as you have more control over dispersion and can limit reflections. I do recommend placing acoustic tiles on the wall directly behind the speakers and crossing to subwoofers no lower than 100 Hz. I cross over at 125 Hz and with eyes closed you would never know there were subs in the system. Also many tweeters have closed backs. If this is the case you'll want to add a rear firing tweeter.
@ozzy62 - thanks for the feedback, seems you have no issues with the amount of bass.

I took a look at the photo on your system page - nice

But I have a few questions...
- how wide is your room.?
- did it take a lot of time to find their ideal position?
- is it better to have more space behind them - I have about 8 ft available
- have you tried them further away from the wall behind them?
- the two large round "Towers" behind the speakers - what do they do?

I know OB designs can be difficult to "master" so any info would be greatly appreciated

It seems you are very happy with the Spatial products you own - I will look into them further.

Many Thanks

@mijostyn - thanks very much for al the info, definitely something to take into consideration.

You mention "Average Room" - what size are you thinking of?

My room is 17ft wide x 42 ft long with an 8 ft ceiling - broadloom covers the floor.

Speaker placement is currently 8 ft from the wall behind the speaker
- i.e. from the wall to the front of the speaker is 8 ft
- this is the upper limit due to furniture
- listening position 8 ft from the front of the speaker

I realize every room has it’s own challenges, but any assistance would be appreciated.


But I have a few questions...
- how wide is your room.?
- did it take a lot of time to find their ideal position?
- is it better to have more space behind them - I have about 8 ft available
- have you tried them further away from the wall behind them?
- the two large round "Towers" behind the speakers - what do they do?
The room is 15.5 X 25. I have the speakers about 55" from the front wall. I tried them further into the room, and closer to the wall, but this seemed like the best position, bringing them further into the room had no positive effect. They aren't hard to place in a room, since bass nodes that have affected other speakers seem to have no bearing on OB bass. I have fine tuned them a couple of times, but the basic position hasn't changed much. They do like a lot of toe in and the sweet spot is pretty small. That's the only negative I can think of.

The round things are home made tube traps. I have had them for many years. I haven't tried to remove them with these speakers. But the bass with the X3 is pitch correct and the most accurate sounding bass I have had in this room.


I agree with Ozzy regarding the quality of bass from the Spatial X series.  I have the X5 which has the powered 12 inch woofer rather than the 15 inch powered woofer of the X3.  My room is a difficult room for bass as it is only 11 feet wide by 24 feet long and has 7 foot ceilings.  I have several bass traps which helped my previous two rel subs but still the bass was never as tight as I would have liked.
The bass quality is much much better with the Spatial X5s and my intention prior to purchasing the X5s was to still use the two rel subs but just cross them lower.

I have mine 50 inches from the front wall and almost 8 feet apart and toed in to almost point at my ears and I sit about 10 feet apart.  I prefer 10 feet away than 8 feet away, the drivers seem to integrate better but I only have about 40 hours on them so I know they will improve with break in.

However I was shocked at the bass quantity and quality and have removed the rels as they do not benefit the bass and actually subtract from the bass quality compared to the X5s alone.

If I had a larger room I would have gone with the X3 but Clayton recommended the X5 for my room and I also thought I would still use the subs but they are now in storage.  
The reproduction of the bass guitar on these speakers is outstanding with very good pitch definition and the speakers go down into the upper 20s according to my test cd.


You have only scratched the surface with 40 hours on the speakers. Mine improved up to and beyond 300 hours. The bass will benefit the most, becoming more prodigious with better presence and slam with kick drum and electric bass guitar. It does get much better than what you hear now.


Yes Ozzy that's what I've heard from many owners which is hard to believe as the bass is already quite good and much better than what I had previously.  It's difficult for me to play them continuously since my family doesn't like it unfortunately.  Anyway I'll try to get more hours on them and look forward to the improvements as well.
I've heard the 100 hour point is significant and that they continually improve as you've mentioned beyond that as well.
To the OP, I reviewed both the PAP Trio15 line (Tang Band, Voxativ, and Horn1), as well as the Tri-Art Audio Series B 5 Open for Dagogo.com 

Every OB speaker has its own design and build characteristics. "Better" is quite subjective. I can set up either of these quite different designs in systems that are captivating. You should familiarize yourself with the primary drivers available and try to gain understanding about how they would sound generally, apart from particular brand, i.e. horn, full range, concentric, etc. 

For your more sizable space I would look at the Quintet rather than the Trio. Due to the arc of the front baffle I wouldn't be concerned about the speaker's top being 1' from ceiling. The horn is exquisitely refined and when set up optimally is stunning in resolution and center image focus. My understanding is that the field coil driver is much better, but I haven't laid hands on it. 

I have a set of PAP Trio with Horn 1 midrange. They replaced a set of B&W 803Ds. Here are my impressions:

I am using the Leonides XO. Have very mixed feelings about this XO. It is a first order XO and does little to roll off either the bass drivers or the Horn 1 midrange. The Horn 1 is good down to 300 Hz or so, and the bass drivers go all the way up to 1500 to 2K Hz (where they have a nasty peak). So there is a large area in the lower midrange where both the Horn 1 and the bass drivers are active. I added an RC network to the bass drivers to try to attenuate the upper midrange somewhat, and it works after a fashion but is not perfect. The speaker sounds great on Jazz but is trying for compressed rock. Am in the process of looking at an active XO system so I can better roll off the horn and the bass drivers at about 800 Hz.

Compared to the B&Ws, the imaging and sound stage depth is vastly better. Even with the frequency response issues, these have much better upper midrange (not as harsh and they don't "beam" like the 803s did). Bass is quite good compared to the B&Ws, which surprised me.

I also have the Voxative drivers which I have yet to try, and may swap these for the horn. The horns use Beyma Spanish made drivers and are incredibly efficient, at 108 dB/Watt. May also take a look at the ESS drivers as these are quite inexpensive at the moment.

I do have to comment on the CS from this company. Ze'ev is quite responsive until he has your money, thereafter not so much. His business model is to drop ship the components from all over the world, so the user has to assemble and test the speaker. We had a number of QC problems (the initial shipment of woofers were damaged by the manufacturer in packaging) and many of the parts were quite late in delivery.

So for me these are a work in progress, which I don't mind so much as I am a tweaker. I think they have real potential if the frequency response aberrations can be brought under control.  
Imo, it's not advantageous to lower the mid-bass as you will make the speaker sound smaller.  Try working with different resistors,  caps (I put in Mundorf oil filled for a beautiful i.provement) and the wiring. All of these are efficacious.  If you have lower end electronics you should not expect extravagance. Also, if speaker is sitting on floor, use some baffle tilt to change relative position of drivers to ear,  as this is a good way to adjust perception of balance of drivers. See my review at Dagogo.com 

Different resistors and capacitors will not change the basic design, which is that of a first order XO. This means that both the horn and bass driver will be operating (and fighting each other) in the lower mid range below 1K Hz. The Eminence OB-A15neo drivers frequency response continuously rises to its peak at 1200 hz, which is very noticeable particularly because the XO does not roll this driver off well before this. When summed with the Beyma compression horn driver (good for below 300 Hz), the lower mid range emphasis is unmistakable. The best electronics in the world will not change this.

I  am using Parasound JC1 amps, not exactly what I would consider lower end electronics. 
dhl93449, I am aware of the crossover’s parameters not changing, and I have no interest in debating my recommendations. I have used all the recommendations I mentioned, and I think you are shortchanging your experience regardless if you do not try them. I don’t recommend insipid and ineffectual changes.

You have a very fine amp, yet there is no way to determine whether sonically it is an excellent match with the PAP-Horn1 aside from comparison to other amps. The speaker will change sound fundamentally, despite the crossover not being changed, also in the region you discuss, from the simple insertion of a different amp. I have used many amps on the PAP-Horn1, and this is a fundamental way of altering the speaker’s performance, simply by change of amp.

Again, I know that the crossover will not change, but for instance, an amp that causes the speaker to emphasize more the top end, most often by having shallower or "lighter" bass, may cause the speaker to sound more balanced to you, as the perception is that there is relatively less emphasis on the mid-bass. I also make such changes with other speakers, such as the Vapor Audio Joule White. You may agree or disagree, but that is simply another point I offer.

I also regularly adjust the holistic sound of speakers by swapping interconnects and speaker cables, as well as power cords. While these do not change the crossover, they change the speaker’s holistic sound, and the perception of an emphasis in one part of the spectrum can be addressed pretty well, though not always perfectly. If you disagree, then we’ll simply accept that the other is at odds and have to let that go.

Based on your reply, I suspect you believe that the only worthwhile solution would be to manipulate the crossover, and if so, then I strongly recommend you consider the PAP-C1 Active Crossover for the speakers. I reviewed it for Dagogo.com, and the bonus for you - as you are familiar with crossovers and filters, is that the PAP-C1 allows for adjustment of both level and filter slope for each driver. This, I suspect, would be a game changer for you and allow you to contour the drivers precisely as you wish. Take a look at the Low and High Pass filter curves on the website. I would put a link to it here, but the moderators seem to restrict my use of links because I am a reviewer. It’s easy enough to find at the website. Obviously, then, as a dummy board is used in place of the crossover, the recommendation of replacing caps or resisters would not be in play, but the "internal" wiring and speaker’s baffle slope would still be worthwhile changes. BTW, with the active X-over and four channels of amps the speaker had a very nice bump in dynamics. 

Now, if you don’t like any of these suggestions, you’re on your own! :)

I considered the C1. I do believe that is the one designed by Nelson Pass for PAP. That gets a lot closer to what I want, and does roll off the drivers properly as opposed to the Leonides passive XO. The C1 and the Leonides are night and day different in how they XO the drivers.

Only issue I have with the C1 is it is not quite flexible enough for me, in that is a single ended design and I used balanced connections and would require buying two C1s. Pass also used 2nd order Linkwitz Riley slopes, which create 180 degree phase shift at the XO point, requiring one of the drivers to be wired out of phase with the other. I would prefer 4rth order LR slopes instead. That said, the C1 is definitely a step in the right direction.

PAP also has a passive 2nd order XO that was used prior to the Leonides version (I think). Have not used that XO, as I was convinced to order the Leonides instead.

dhl93449, you know precisely what you are after. You are right about this, "The C1 and the Leonides are night and day different in how they XO the drivers," as I have heard the difference and it is significant. 

Maybe discuss with Pass Labs whether an XLR version of the PAP C1 could be made for you. The other possibility is to get a digital x-over and do your own slopes. One industry member who does similar with his speakers is Chris VenHaus of VH Audio. He would be able to tell you what software he uses to build filters.   

Anyway, if you contact Chris, please respect his time, as he is quite busy with VH Audio. But, I'm sure he would be able to point you in a direction in terms of establishing a digital X-over.  

Well I decided to build my own active XO, based on a class A discrete op amp design (a modified Spectral design using a Pass Labs type JFet output stage). Took quite a while to build and test due to the number of amps involved. Also had to procure two more JC-1s. I substituted the Voxative midrange driver for the Horn, and cross the bass drivers over at 400 Hz with 4rth order Linkwitz Riley slopes.

Resulting sound is amazing. Best my system has ever sounded. Considerably better than the Horn 1 with the passive Leonides XO. I have yet to try the horn with the electronic XO (400 Hz is probably a bit too low and would have to alter my XO point to 800 Hz), but the Voxative sounds so good I may not bother with the horn. Gone is all the stridency in the vocals and the symbols and bells are wonderful. 

As an addendum, since you mentioned VH Audio. I am using their teflon caps in the critical low pass and high pass filters.
dhl93449, congratulations on advancing your system! It's obvious you had a goal and know how to achieve it. This supports once again the conclusion that an active x-over holds the potential to outperform a passive. The addition of two more amps completely changes the game with any speaker; properly, you have done upgrade to speaker and to amplification. The power delivery and crossovers have changed, and that is a radical upgrade to a system - as is evidenced by your obvious pleasure with the result.  

Just because the results are fantastic doesn't mean it can't get better. Why not try the horn to get it to the same, and perhaps higher level of sound quality? If you have the driver available, I strongly suggest you do. Try all permutations. If it were me, I would work to achieve the absolute best with both, then have the option of swapping them out for variety. Especially since you have put in a fair bit more money in buying two additional JC1's, I would want as much result/performance as possible.  

I know its been quite a while since your last post to this string but here is my update to your suggestions. I tried the horn again and lowered the XO point to 400 Hz. Still was not that satisfied as there appears to be something missing at the very top end. Sold them (the PAP horns) and the new buyer confirmed the same observation. Many have added a "super tweeter" to the horn to fix this, but since that requires yet another XO point, I decided not to pursue this complexity as my current active XO is two way only. My in room pink noise measurements confirmed a drop off in frequency for the horns at about 10-11K Hz so this explains a lot. The Voxativ AC 1.5 reaches up to 15-16KHz in the same setup. The Voxativ is nice and flat with the main speaker chassis pointed straight ahead (as the off axis response is flat). They have a slight peak at 10KHz on axis, so I listen to them straight on (an not towed in as with the horns).
One additional advantage I have found with my active XO. I can tune the upper frequency response (to the Voxativ) by 0.5 dB increments and this really helps in tweaking certain recordings. I also built in an old school Yamaha (80's era) high frequency "tilt" control which tilts the HF response by variable degrees ( 1 through about 6 dB at 20KHz; hinged at 800 Hz). Don't really care for this much as the fixed shelving response works better for me.
One additional addendum. Looking to perhaps upgrade to the Voxativ PiFe. This is the driver similar to the AC 1.5, but with wood cones and phase plug. Cannot find any comparisons between these two drivers, except from Ines at Voxativ, who claims the wood makes the driver smoother and more detailed. Comes at quite a cost as these are about $5K a pair. 
It would be a plug and play replacement for the AC 1.5 as far as the XO goes, which makes life simple. Another suggested tweak is to replace the Al metal phase plugs in the 1.5 with a wood version from the upper end drivers, but I'll be d'mned if I cannot get a grip on those plugs to remove them.
I have heard the trios and the quintets.
IMO not a good speaker. Can be loud? yes. Are they heavy? yes, very.
Do they sound good? No. 
Very low definition. Can't play them at low volume.
I would not buy them. I would not take them if someone offered them to me for free.