Fostex FE206En Rear-Loaded Horn Speakers

Once again Mark tries on the Fostex FE206En high sensitivity fullrange driver, but this time in large rear-loaded horn loudspeaker cabinets. The horn speaker cabinet plans are from the FE206En driver datasheet.

Fostex FE206En Rear-Loaded Horn Speaker Cabinet

Each horn speaker cabinet is made up from thirty-six pieces of 21 mm thick pine plywood.  Australian beeswax is used on the outside of the horn cabinet and heavy cedar oil was applied to the mouth of the horn.

The sensitivity of the FE206En driver is greater than 96 dB / 1W / 1m, so the rear-loaded horn speakers are very well suited for use with very low power tube amplifiers.

Fostex FE206En Back-Loaded Horn Speakers with 6EM7 SET Amplifier

Mark reports very good performance from the back-loaded horn speaker cabinets.

"Where this type of single driver loudspeaker system does shine is in it's ability to image. The back-loaded horn speakers can draw an extremely accurate soundstage. This is due to the fact the all the music is coming from a single point and is not smearing the sound over multiple drivers." 

"Big, bold and made of pine they are. Excellent sounding they are also. For me, with my Paris amplifier (dual mono SE 6EM7 integrated with 4S tube preamp) in triode mode, the combination of a high sensitivity speaker, razor sharp sound stage and extended and very clean mid-range, can lead to a whole new listening experience." 

Full project details are available on the Fostex FE206En Back-Loaded Horn Speaker page.

DIY Nearfield Monitor Speakers with Fostex FE103En

Fostex FE103En DIY Bass Reflex Bookshelf Speakers

These small computer desktop speakers were built using the in-expensive Fostex FE103En fullrange speaker drivers following the bass reflex enclosure box plans that were provided with the FE103En datasheet.  The enclosure volume is noted as 6 L and tuned to 95 Hz but the the gross volume was calculated to be 6.9 L and the box tuning frequency to be about 97 Hz.  The Fostex FE103En drivers are 100 mm in diameter and have a rated sensitivity of about 89 dB / 1 W / 1 m.  There are a couple of easy modifications that can be made to improve the FE103En drivers which are described in detail on the modifications and tweaks for the small Fostex fullrange speaker drivers information page.  A photograph of the stock Fostex FE103En drivers is shown below.

Fostex FE103En Fullrange Speaker Driver

The speaker cabinets are built from 15 mm thick Baltic birch (11 ply multiplex) plywood.  Acousta-Stuf fiber fill is used inside the speaker enclosure to dampen the rear wave from the driver and to reduce standing waves and internal reflections.  The finished speakers are shown below with the computer.  Since this position the speakers are used in the nearfield, there is no need for a baffle step compensation filter.  The  Fostex FE103En DIY Bass Reflex Bookshelf Speakers project page has full details regarding baffle step compensation for farfield use and pairing the speakers with a subwoofer.

DIY Bass Reflex Monitor Speakers with Fostex FE103En  

These little speakers have bee in use with the desktop computer in the office for a few months now and I am quite pleased with the end results.  With no crossover or filters the speakers deliver wonderful playback full with rich details.  For full project details see the Fostex FE103En DIY Bass Reflex Bookshelf Speakers (Nearfield Monitor) project page.

More Single Driver DIY Speaker Projects

• Zigmahornet Speakers with Fostex FE103E / FE103En
• Fostex FX120 DIY ML-TQWT Speakers
• Fostex FX120 DIY Bass Reflex Bookshelf Speakers
• Fostex FE206En Double Bass-Reflex Speakers

Fostex FE206En Double Bass-Reflex Speakers

Fostex FE206En Double Bass-Reflex Speakers

Fans of low power tube amps love high-sensitivity full-range drivers like the 200 mm Fostex FE206En and with good reason.  The drivers are relatively inexpensive, they sound good and they do not require a crossover.  The main reason for the fan fare is because of their high sensitivity (96 dB / 1 W / 1m), which makes them ideal for use with very low power amplifiers.  However, the high sensitivity and wide frequency bandwidth of the driver come at a cost - a very low mass paper cone and a tiny excursion (Xmax=0.8 mm).  This adds up to mean that extracting bass from the Fostex FE206En is often a challenge.  The common solution to this challenge is a large back-loaded horn type enclosure.

Fostex FE206En Back-Loaded Horn Speaker Enclosures 

The problem is that these elaborate back-loaded horn type enclosures often require a skilled woodworker to construct.  The Fostex FE206En driver datasheet also include a recommended enclosure plan for a suitable bass-reflex type enclosure which is far easier to construct.  Mark has built a couple sets of the Fostex FE206En double bass-reflex speakers and reports that the simple enclosure works well with the FE206En full-range driver.

Fostex FE206En Double Bass-Reflex Speakers 

Since Mark will be using the speakers as part of his home theater setup, undercoating paint was used for a stipple like flat black and non-reflective finish.  Mark reports that the speakers are an excellent mate for use with his 6EM7 SET amp.  Full details are available on the Fostex FE206En Double Bass-Reflex Speaker project page.

More Single Driver DIY Speaker Projects

• Fostex FE103En Bass-Reflex Monitor Speakers
• Zigmahornet Speakers with Fostex FE103E / FE103En
• Fostex FX120 DIY ML-TQWT Speakers
• Fostex FX120 DIY Bass Reflex Bookshelf Speakers

BK-12m Folded Horn Kit - Fostex FE126En

There is a new high-sensitivity folded horn speaker kit being offered by Madisound.  The new BK-12m is a single-driver folded horn speaker kit that follows in the lineage of the BK-16 and BK-20 designs.  The BK-12m uses the Fostex FE126En full-range speaker driver in a custom folded horn enclosure while the driver is run full range with no filters whatsoever.  The Fostex FE126En driver is 4.7" (120 mm) in diameter with a rated sensitivity of 93dB/W(m).  This high-sensitivity means that the BK-12m speakers will be suitable for use with low powered amplifiers.

BK-12m Folded Horn Kit - Fostex FE126En

The enclosure panels are made using high quality 5/8" (16 mm) thick Baltic Birch multiplex cut using a CNC machine and bundled as a flat pack.  Once completed the speaker cabinets have overall dimensions of 31-5/8" x 7-1/4” x 14-1/2" (800 x 185 x 370 mm).  The Birch plywood is unfinished so you can finish the speakers how you like.

The BK-12m speaker kit includes:

• 2 x Fostex FE126En 4.5" Full Range Drivers;
• 2 x Unassembled, unfinished Baltic Birch Cabinets;
• 3 oz. Acousta-Stuff internal damping material;
• 5 ft Supra Classic 1.6 15 AWG speaker wire;
• 4 x QC187 Quick Connects (2 red, 2 black);
• 8 x 8X1 Socket Head Wood Screws (8x Philips Head wood screws also included);
• Assembly Instructions.

To put the kit together you will need just a screwdriver, wood glue, sand paper, bar clamps and binding posts.  An inside view of the folded horn speaker enclosure is shown in the photo below.

 

Inside - BK-12m Horn Speaker Kit - Fostex FE126En

 The BK-12m kit is available from Madisound for $315US + shipping.  For full details about the BK-12m speaker kit see the product page at Madisound.

More single-driver speaker kits and projects:

• Tang Band D4-1 DIY Back Horn Speaker Kit
• Fostex FX120 ML-TQWT Speaker Project 
• Fostex FX120 Bass Reflex Bookshelf Speakers

Feastrex NF-5 and NF-5ex Drivers at SSI 2011

We are big fans of single full-range driver loud speakers so we were excited to check out the Feastrex drivers. Michael Tang of Mike Tang Audio is importing the Japanese Feastrex NF-5 and NF-5EX drivers into Canada and had them on display at the show.

The 5" Feastrex NF-5 ($2000CDN, shown above) uses a large Alnico magnet.  The handmade cones are made from Japanese Washi paper (a higher density fibrous paper) which is impressed in a spiral pattern with embossed ridges.  The drivers surround is made from lamb skin.

The 5" Feastrex NF-5ex ($3000CDN, shown above) uses the same Washi paper cone and a lambskin surround, but with a motor that uses a field-coil magnet (electromagnet).  The field-coil magnet can be operated between 10 and 17V dc.  Changing the voltage allows you to change the damping of the driver.  Michael uses a 12V car battery for the field-coil magnet.  16 ohms, 95 dB, 35 to 25,000 Hz (+/- 3dB).

A Mastersound Compact 845 SET powered the 5" Feastrex NF-5 drivers which were housed in a bass reflex enclosure (enclosure plans from Feastrex, shown below), no passive filters were used.  The speakers sounded excellent, wide soundstage and impressive depth.  The single drivers delivered superb clarity with vocals to die for. 

 

Michael indicated that he is working on a transmission line enclosure design for use with the Feastrex NF-5 and NF-5ex drivers which he plans to have ready for the TAVES (Toronto Audio and Video Entertainment Show) this fall.

More Salon Son & Image 2011 Coverage

• Orangutan O/96 High Sensitivity Speakers
• Little Horn Speakers by Specimen Products
• New Solen.ca DIY Speaker Kit
• AuDIYo.com room (Dynaco ST70 upgrades)
• Voxativ Ampeggio Rear Loaded Horn Speakers 
• Salon Son & Image 2011 - diyAudioProjects.com Show Coverage thread

Voxativ Ampeggio Horn Speakers at SSI 2011

There were a number of ultra high-end Hi-Fi systems at the Montreal show and like last year, my favorite Hi-Fi systems at the show was once again a low powered single-ended tube amp matched with high sensitivity fullrange drivers.  My favorite this year were the new German made Voxativ Ampeggio single-driver rear-loaded horn speakers.  The hand built rear-loaded horn enclosures are built in a collaboration between Voxativ and the famous German piano factory Schimmel Pianos. The cabinet surface is finished with a minimum of 13 applications of hand polished lacquer covered in real piano lacquer. The finish on the loudspeakers was simply amazing.

The product literature lists the following specifications for the Ampeggio:

Frequency Response: 38 - 20,000 Hz
Sensitivity: 101 dB / 1w / 1m
Impedance: 10 ohms
Dimensions (W x H x D): 16" x 43" x 14" (40 x 110 x 35 cm)
Weight: 121 lbs (55 kg)
Cost: $29,750US

The lone transducer used in the Ampeggio is the Voxativ AC-3X, which is their largest neodymium driver and unavailable for purchase.  The drivers suspension is made from goat leather.  The loudspeaker systems does not use any crossover components.

A Don Garber Fi WE421A ($3275) single-ended triode amplifier  (a single dual triode), putting out just 5 watts per channel was used to drive the Ampeggio speakers.  With a sensitivity of 101dB it was plenty loud.  The high sensitivity and easy 10 ohm loads means these speakers will mate very well with low power SET amplifiers.  The Ampeggio speakers sounded every bit as wonderful as they looked.  Open, dynamic, excellent clarity and plenty of detail.

More Salon Son & Image 2011 Coverage

• Orangutan O/96 High Sensitivity Speakers
• Little Horn Speakers by Specimen Products
• New Solen.ca DIY Speaker Kit
• AuDIYo.com room (Dynaco ST70 upgrades)
• Feastrex NF-5 and NF-5ex Fullrange Drivers 
• Salon Son & Image 2011 - diyAudioProjects.com Show Coverage thread

Little Horn Speakers - SSI 2011

The unique looking "Little Horn Speakers" caught my eye and I was particularly excited to see they use a familiar transducer, the Fostex FE108E Sigma.  While their size is far from what most would describe as a little speaker, they are little for a horn.  [Click on the images to enlarge]

The custom handcrafted speakers are produced by Specimen Products from Chicago.  The enclosure (base) is made using Baltic birch plywood and this acts as the compression chamber.  The horn is cast using a heavy-duty resin and both the base and horn are finished with lacquer.

The overall height is 36" (915 mm) and the bell of the horn is 14" (355 mm) across.  The base is an 8" (200 mm) cube.  The impedance is noted as 8 ohms with a sensitivity of 90 dB.  The frequency response is listed as 77Hz to 23kHz.  The speakers are well suited for use with low power tube amplifiers.

 

The Little Horn Speakers delivered a surprising large soundstage and you get the single-driver finesse and detail that FE108E Sigma is known to deliver.  The speakers retail for $2400 / pair are available in a number of colors.  More information and photographs are available from Specimen Products website. 

More Salon Son & Image 2011 Coverage

• Orangutan O/96 High Sensitivity Speakers
• New Solen.ca DIY Speaker Kit
• AuDIYo.com room (Dynaco ST70 upgrades)  
• Voxativ Ampeggio Rear Loaded Horn Speakers
• Feastrex NF-5 and NF-5ex Fullrange Drivers 
• Salon Son & Image 2011 - diyAudioProjects.com Show Coverage thread

New Fullrange Drivers by Tang Band Speakers

Tang Band Speakers has announced four new fullrange speaker drivers which will be added to their growing lineup of drivers.  The new paper fullrange drivers are sized at 3" ,4" ,5"  and 6".  The drivers appear very similar to the 8" Tang Band W8-1772B and W8-1808B fullrange drivers in that they all feature a die cast frame an underhung motor design with a multiple-element neodymium magnet system.  Instead of a cloth half-roll surround the new drivers use a rubber surround.  The Xmax of the fullrange drivers is a healthy 4mm for the 3" unit and 5mm for the 4", 5" and 6" drivers.  A unique looking phase plug is used to prevent phase cancellations and improve high frequency extension and dispersion.

Tang Band W3-1878 Fullrange Driver

Nominal Impedance 8 ohms, DCR 6.5 ohms
Sensitivity 1W/1m, 88 dB
Frequency Response, 75-20kHz
Free Air Resonance, 75 Hz
Rated Power, 12 W
Maximum Power, 25 W
Qts, 0.28 
W3-1878 datasheet.

Tang Band W4-1879 Fullrange Driver

Nominal Impedance 8 ohms, DCR 6.3 ohms
Sensitivity 1W/1m, 87 dB
Frequency Response, 55-20kHz
Free Air Resonance, 55 Hz
Rated Power, 25 W
Maximum Power, 50 W
Qts, 0.43

W4-1879 datasheet.

Tang Band W5-1880 Fullrange Driver Nominal Impedance 8 ohms, DCR 6.3 ohms
Sensitivity 1W/1m, 88 dB
Frequency Response, 45-20kHz
Free Air Resonance, 45 Hz
Rated Power, 30 W
Maximum Power, 60 W
Qts, 0.32

W5-1880 datasheet. 

Tang Band W6-1916 Fullrange Driver

Nominal Impedance 8 ohms, DCR 6.8 ohms
Sensitivity 1W/1m, 91 dB
Frequency Response, 60-20kHz
Free Air Resonance, 60 Hz
Rated Power, 30 W
Maximum Power, 60 W
Qts, 0.46

W6-1916 datasheet. 


There is no indication on pricing or when the drivers will be available.

Similar Posts:

• Tang Band D4-1 DIY Back Horn Speaker Kit

What's Playing: Roy Orbison - All-Time Greatest Hits (MFSL - Gold)

Tang Band D4-1 DIY Rear Horn Speaker Kit

This winter I wanted to build another set of speakers but there were a couple of problems. My woodworking skills are not great and I don't have a heated workshop where I could work as sawdust and paint fumes are typically not welcome in the home. With that in mind I was looking for a speaker that required not cutting or finishing and came across the Tang Band D4-1 DIY Back-Loaded Horn Speaker Kit.


The kits as supplied is 100% ready to build with all the necessary parts and tools required except for a soldering iron. There is no cutting required and the small speaker kit goes together just like the ready-to-assemble furniture that you would find at Ikea. The enclosure just stacks up and is held together with hex screws. The enclosure is a rear-loaded expanding horn which houses a single fullrange driver, the Tang Band W4-1617.


The enclosure was very simple to put together and the exterior wood face came pre-finished with a low gloss finish. The finish looks like it it can be lightly sanded and painted should one desire a different finish. The overall dimensions of each enclosure is 162 mm x 320 mm x 500 mm (W x H x D) and the finished speakers weigh 10.9 kg each.

The net result is a simple, attractive and compact back horn speaker that sounds great and is fun to build!

For full details see the Tang Band D4-1 DIY Back-Loaded Horn Speaker Kit review.

What's Playing: The Traveling Wilburys - Last Night

Simple DIY Monitor Speakers

We recently received an email asking for some clarification about the difference between line-level and speaker-level Baffle Step Correction Circuits with a reference to the DIY S.E.Xy Speaker Project over at Bottlehead.com. This message brought our attention to a very simple speaker project that we thought we would point out to our readers. A photograph of the S.E.Xy Speaker Project is shown below.


In short, the small sealed monitor speakers are comprised of inexpensive Fostex FE166E fullrange drivers and housed in prefabricated Dayton Audio 0.25 ft^3 cabinets from Parts Express. This is a very simple speaker project and the only woodworking required is a couple of holes through the front baffles for the drivers (electric drill and a hole saw should do).

What caught my attention with this project was the fact that the 6.5" Fostex drivers actually fit in the small prefabricated speaker cabinets. While I have used the great looking Dayton Audio speaker cabinets in the past, I never bothered to check if the 6.5" Fostex drivers would fit.

Fostex FE166E vs FE167E
Of course some of you may prefer to use the Fostex FE167E fullrange speaker driver in place of the FE166E and that should not pose any issues. The FE167E has the same efficiency of 94dB but with it's higher Qts it will be able to produce more bottom-end which will allow you to lower the crossover point and possibly even allow you to get away with just one subwoofer. The figure below shows the modelled frequency response of the two drivers in a 0.25 ft^3 sealed enclosure.


The modelled response shown above uses the T/S Parameters noted on the Fostex data sheets. However, based on our experience with measured T/S Parameters from other Fostex drivers, expect Qts to be a little larger than noted on the data sheet. This means that we can expect a little more bass than what is shown on the plot. In addition to getting more bass out of the FE167E, you may also prefer it as it does not exhibit the rising frequency response of the FE166E which some may find too shouty.

Baffle Step Compensation: Line-level vs Speaker-level
This speaker project was meant for use with the 2W Bottlehead Single Ended eXperimenter's amplifier and therefore Line-level Baffle Step Compensation is the most practical choice as it won't waste the precious power of small tube amps. If power is not a concern, you can use the Baffle Step Circuit Calculator to come up with suitable speaker-level circuit.

For those wondering about the line-level BSC I have run a couple of simulations. I did not know the input impedance of the Single Ended eXperimenter's tube amp so I assumed 100k-ohms.



It would be a good idea to try the BSC on a protoboard and adjust the values to suit your room and personal taste. I would start without the 1.2nF (0.0012uF) capacitor, especially with the FE166E.

The inexpensive Fostex drivers work well in sealed enclosures. I am still very happy with my Sealed Fostex FE127E Bipole Speakers. For those of you afraid of woodworking, the prefabricated Dayton Audio cabinets are for you. Also, for the time being PartsExpress is offering free shipping on most orders over $98 (limited to USA).



More DIY Bookshelf Speaker Projects:

• Fostex FX120 DIY Bass Reflex Bookshelf Speakers
  
• Fostex FE127E DIY Bass Reflex Bookshelf Speakers
• Fostex FE167E DIY Bass Reflex Bookshelf Speakers
  

What's Playing: Emilie Mover - That Song

Fostex FE167E Bass Reflex Speakers

by Mark Houston


The very first pair of speakers I put together some thirty-eight years ago was a pair of single-driver loudspeakers using 8” Kaltro twin cone drivers. As I type this, I find myself once again listening to speakers using a single full-range driver. This time it is the 6.5” Fostex FE167E fullrange driver. I had recently completed a small low wattage 6T9 valve amplifier, and asked Gio for some suggestions on speakers to match the amp. He suggested the Fostex FE167E. When I saw they were 94dB efficient I ordered them instantly. Packaged with the drivers were two enclosure plans - a floor-standing unit as well as a bookshelf enclosure. I opted for the smaller bookshelf speaker box. The Fostex Recommended Standard Bass Reflex Type Enclosure is 15L with a 50 by 50 mm port that can exit from the front or rear. The enclosure plan is shown below.


The speaker boxes were put together by a neighbor using 18 mm MDF. The boxes were clamped during the gluing process and the inside joints were sealed with additional glue. The back panel had heavy speaker sound absorbing vinyl glued over its surface and the box was lined with a single layer of thick Dacron (tontine).


The binding post block was fitted and oxygen free copper speaker wire was used for the connections. Sealing sticky back foam was placed under the connecting block and also under the drivers which were screwed in place. The boxes were pre-sprayed with paint. Later grills were added by cutting the center out of a piece of MDF, stretching and stapling speaker cloth over the frames. The grills were attached to the speakers using Velcro.


The baffle step correction / compensation (BSC) calculator can be used to determine a BSC specific to the width of your baffle. The amount of attenuation required will be subject to your listening room and amplifier as well as personal taste. Typically about 4 to 6 dB of attenuation is good. You can experiment with the component values shown below and select a BSC to suit your room, amplifier and personal preference. I am using L=1mH and R=2.7ohms.


Out of the box the first thing you notice about the speaker drivers are the ultra-light the cones and very stiff suspension. The first few days of playing will see the drivers settle though expect to put in twenty to fifty hours before they settle completely. If you are not use to listening to single-driver loudspeakers you may be a little shocked at first. I was, but it doesn’t take long to recognize the all the good qualities of a single-driver speaker system. At a recent Melbourne Audio Club night held at my residence the Fostex FE167E speakers were auditioned with a small 6T9 tube amplifier and they received many accolades from the very discerning listeners. When compared with small 2-way bookshelf speakers the Fostex FE167E produced more bass and equal treble response. Most members could not choose one pair of speakers over the other. Voices however do appear forward on strong vocal tracks. This is not unpleasant just obvious.


When teamed with the 6T9 tube amp, for which they were intended, they really come into their own. They are LOUD with only a few watts driving them, produce good bass and excellent mids and highs. The Fostex recommended enclosure design works well with the drivers and produces some excellent violin and cello gritty earthy notes in the instrument's resonance and character. Piano sounds soft, rounded and musical. Voices tend to come forward a little of the rest of the instruments as do some upper-middle frequencies. This adds some extra dimension to your listening.


Update: 4 May 2009
The plot below shows the measured near field response of the speaker system. The upper line on the plot is the measured response with no filters in place. The lower green line is the response with a baffle step compensation circuit of about 3dB.


See the Fostex FE167E Fullrange Driver page for more information and enclosure ideas for this driver.

More DIY Bookshelf Speaker Projects:

• Fostex FX120 DIY Bass Reflex Bookshelf Speakers
  
• Fostex FE127E DIY Bass Reflex Bookshelf Speakers
• DIY Sealed Jordan JX92S Bookshelf Speakers

DIY Jordan JX92S Tower Speaker

Gary from the United States has put together a fantastic looking pair of tower loudspeakers. His speaker project uses the Jordan JX92S Fullrange Driver which I have used myself and is a fantastic fullrange driver.


The fullrange JX92S speaker is housed in a vented enclosure with a volume of about 1.3 cubic feet and a box tuning of about 35 Hz. As you can see, Gary has done a great job with the finish on the DIY speaker cabinets. The enclosure is constructed using Baltic birch plywood and finished with maple and walnut veneer and a tung oil stain.



Gary reports that the Jordan JX92S drivers can deliver a lot of bass which is uncommon for fullrange drivers of this size class. He also indicates that the speakers sound great, open, tight, fast and as expected, image like crazy. The nice thing about these drivers is that they can also handle all types of music without any signs of strain.

For additional information, pictures and enclosure design, see the Jordan JX92S Tower Loudspeaker Page.

Additional Jordan JX92S DIY Loudspeaker Projects:

• DIY Jordan JX92S Transmission Line Speakers (ML-TL)
  
• DIY Jordan JX92S Bookshelf Speakers (Sealed)

What's Playing: Warsaw - Transmission

DIY Jordan JX92S Open Baffle Speaker

Martin J. King of Quarter Wavelength Loudspeaker Design has added a new DIY open baffle loudspeaker project to his site. Martin's loudspeaker project uses a Jordan JX92S full range driver mounted on an open baffle in conjunction with a Goldwood GW-1858 woofer which is mounted in an H-frame. The picture below (click to enlarge) shows the new open baffle speaker design set up next to his Lowther DX3 ML-TL speakers.


As you can see, the enclosure is fairly simple and relatively compact (for open baffle speaker systems). The two-way dipole speaker systems covers most of the 20 Hz to 20 kHz frequency range. The H-frame configuration is used for the bass below 200 Hz and the small Jordan full range driver are for the frequency range from 200 Hz to 20 kHz.

As with all of Martin's loudspeaker projects, his latest is also very well documented and very informative. For full details about this loudspeaker project, see Martin's writeup: Jordan JX92S Open Baffle and Goldwood GW-1858 H Frame Two Way Speaker System - (PDF 1.68MB).


Related Jordan JX92S DIY Loudspeaker Projects:

• DIY Jordan JX92S Mass Loaded Transmission Line (ML-TL) Speaker
  
• DIY Sealed Jordan JX92S Bookshelf Speaker
• DIY Jordan JX92S Bass Reflex Tower Loudspeakers
  

What's Playing: Kate Bush -King of the Mountain

DIY Sealed Jordan JX92S Bookshelf Speaker

A while back I purchased a pair of Jordan JX92S fullrange speakers. At the time I purchased them I didn't really know what I was going to do with them, but having read so many positive comments about these drivers, I really wanted to hear them for myself. At $180 each, the drivers are costly, but these drivers have a large Xmax, good low end extension and a fairly smooth frequency response. It is uncommon to find all of these attributes in a medium sized fullrange unit. I was eager to hear these drivers, so I figured I would first try them in a sealed loudspeaker enclosure, with the idea to convert the box to a bass reflex or aperiodic enclosure later on. Figure 1 shows the calculated frequency response for the JX92S driver in a 0.25 ft^3 sealed box. The orange line is the calculated response using the manufacturers T/S parameters and the yellow line is the calculated response using parameters that I measured with a Dayton Audio Woofer Tester 3 (WT3). The calculated impedance is shown in Figure 2. See the Jordan JX92S fullrange driver page for the measured Thiele-Small (T/S) Parameters.

Figure 1: Calculated Frequency Response - Jordan JX92S in 0.25 ft^3 Sealed Box

Figure 2: Calculated Impedance Response - Jordan JX92S in 0.25 ft^3 Sealed Box

For the loudspeaker enclosure I used prefabricated 0.25 ft^3 curved cabinets from Parts Express
. A rectangular or do-it-yourself (DIY) box of the same volume would also be fine. Damp the walls of the cabinet with upholsterers felt or use poly fill to stuff the box. Adjust the damping materials to suit your taste. The driver is counter sunk, but I didn't have any black low profiles screws on hand and I wasn't about to run out to buy some.

Photograph 1: Jordan JX92S in a 0.25 ft^3 Sealed Loudspeaker Box - Front

Photograph 2: Jordan JX92S in a 0.25 ft^3 Sealed Loudspeaker Box - Rear

The measured frequency response is shown in Figure 3. The frequency response measurements were completed using a Radio Shack 33-2050 SPL Meter. On axis, this is a fairly smooth driver. At about 15 degrees and more off axis, the high frequency response drops off rapidly due to beaming.

Figure 3: Measured Frequency Response - Jordan JX92S in 0.25 ft^3 Sealed Box

The impedance response was measured using the Dayton Audio Woofer Tester 3 and is shown below in Figure 4.

Figure 4: Measured Impedance Response - Jordan JX92S in 0.25 ft^3 Sealed Box

The temptation will be run these drivers fullrange and some may actually be happy by only sucking the drivers up against the wall. However, most people will likely prefer some amount of baffle step correction / compensation (BSC). The amount of attenuation required will be a function of the listening room, amplifier and personal taste. I was happy with about 4.5 dB of attenuation (Lbsc=1mH and Rbsc=3R9 for a 7.5" wide baffle). You can use the online baffle step correction calculator to determine a suitable circuit for your baffle width and desired attenuation.

Photograph 3: Temporary BSC for Jordan JX92S Sealed Loudspeaker

Most will likely be satisfied with this driver running fullrange plus a simple BSC. However, off-axis the high frequency response starts to quickly disappear. Personally, I like to toe the speakers so they cross just in front of the listening position with Radio Shack 40-1310 Super Tweeters toed out at the same angle. Add a diy active subwoofer (I cross mine in at ~60 Hz) and this makes for a very pleasant and simple 2 channel system. It seems that everyone who hears these drivers prefers them over the Fostex FX120. Myself, I prefer the FX120. I don't find the JX92S as "engaging" as the FX120. Next step is to convert the speaker box into an Aperiodic Loudspeaker Enclosure. Stay tuned.

Related DIY Jordan JX92S Loudspeaker Projects:

• Jordan JX92S Mass Loaded Transmission Line (ML-TL) Speaker
• DIY Jordan JX92S Bass Reflex Tower Speaker Project
  

What's Playing: Sarah McLachlan -The Path of Thorns (Terms)