Eminence Beta 12LTA on Open Baffle

Eminence Beta 12LTA on open baffle

This is my favorite ‘full range’ speaker even tho it’s not really full range. It gets nearly everything right – but you must modify it in order to smooth out its roughness and add a super tweeter to extend its high frequencies. It can be used in sealed, ported or open baffle type cabinets. I’ve even read about a monster sized BIB back horn that lives somewhere. I use the 12LTA on an open baffle. In addition, a helper woofer in the form of a powered H-frame, provides bass.

The Eminence Beta 12LTA frequency response extends high enough into the treble that adding a super tweeter seamlessly is easy. I’ve tried the old Radio Shack pod super tweeters with good results. I’ve also tried the Eminence ASD 1001 with better results.

Modifying the 12LTA is easy. Just remove the dustcap. Once removed the sonic character of the driver smoothes out noticeably. Further smoothing results when fitting the driver with a phase plug. A pair of phase plugs was donated to me by JRKO. Thanks, they are awesome! The sonic difference between adding the phase plug and not was minimal to my ears even tho the charts below indicate improved performance. Simply removing the dusctap is all that’s required to eliminate a slight cupped quality.

beta-12lta-measurements

Eminence Beta 12LTA measurements with and without dustcap.

Link to original thread at diyaudio.com:

http://www.diyaudio.com/forums/full-range/179161-beta-12lta-3cf-box-port-size-10.html#post2429767

Immediately, I was smitten by this driver. I’m a full range driver fanatic. I love the coherence a speaker without a crossover can provide, but the 12LTA also has dynamic power none of the drivers in my collection exhibit. This dynamic power is expressed as an easy confidence. From the most delicate violin to the most complex orchestral swings, the 12LTA handles everything with aplomb. Even Rock & Roll sounds great, something most full rangers can’t claim.

Having experimented with several full range drivers on open baffle it was just a matter of time before trying the 12LTA. Interestingly, in my system, any driver from 3″ all the way up to 12″ uses the same form factor – a simple 19″ x 19″ baffle sitting on top of an H-frame.

The tweeter simply utilizes a 1.33uf capacitor as its crossover, nothing else is needed. Treble is only as good as the supporting tweeter – but it must be efficient! Pro Sound compression tweeters are a good match for the 12LTA and since this application uses just the tippy top octaves of what the tweeter produces the harshness is eliminated. I was pleasantly surprised to hear how nice Pro Sound tweeters sounded when implemented this way. It’s a tricky thing finding the right capacitor to use with a tweeter in any application. Even tho I settled on 1.33 for the ADS 1001 tweaking the treble up a notch on the Spotify EQ brightened things up nicely without introducing any additional sibilance or other unwanted artifacts. In other words, I liked how the speaker sounded when I raised the treble.

The Eminence Beta 12LTA is rated at 97db per watt. This is the most efficient driver I have. It’s clearly more efficient than the Fostex 168z and Tangband 1808 which are rated at 94db and 93db respectively. The 12LTA bristles to life with just a few watts and sings beautifully with low powered tube or digital amps. It even rocks with solid state! If you’re seeking high efficiency, this driver is tough to beat – and that includes Lowther, among other pricy full rangers.

The driver’s balance is warm and full thru the midrange. Critically, I’d say male vocals are nearly perfectly reproduced while female vocals are slightly less realistically rendered. This is where blending the tweeter is critical or Norah Jones and Diana Krall will sound slightly cupped. But this is an easy fix given some patience integrating the tweeter. I’d recommend experimenting with capacitor values between .47uf and 2uf. I started with 2uf (which was too bright) and worked my way down to .47uf (which was too dull). The tweeter you select will determine the best capacitor values.

Once you have dialed in your tweeter to taste the 12LTA is incredibly musical. On open baffle, imaging is superb. Instruments pop like nothing I’ve heard before. Musicians occupy their own space and the image produced is very broad and deep. I understand this is contrary to typical audiophile theory that smaller drivers and slimmer cabinets have superior imaging but this is not what I hear. A handful of better drivers produce ghostlike imaging some of the time but none as consistent as the 12LTA. Additionally, crescendos swell like nothing I’ve heard before. In my home, there seems to be more than sufficient headroom – these speakers play very loud!

The superior imaging can also be attributed to the driver being on an open baffle. Personally, I feel open baffle produces the most realistic imaging. But this is a preference not everyone shares.

I love music and can enjoy long listening sessions with many full range drivers I own. Having recently been thru an enjoyable experiment where 3″ drivers were the norm, I’ve gone much larger with the 12LTA and feel I’ve lost none of the excellent qualities of the smaller drivers (as long as I can include a helper tweeter). In fact, perhaps the addition of a tweeter improves treble further. If you are looking to ‘go big’ and can get your head around the idea that a large diameter woofer can perform as well – or better – than smaller drivers then I can’t recommend the Eminence Beta 12LTA enough. With some elbow grease (removing dustcap and integrating a tweeter), I believe you come out on top of nearly all full range drivers on the market today. What you end up with is a speaker that does it all without compromise. Whether it’s Classical, Rock, Folk, Girl & Guitar or Techno Synth, this speaker provides sound with incredible ease of presentation, scale and realism.

The large, wide range, Eminence Beta 12LTA is a purpose built Pro Sound driver. It was designed by engineers and contains no black magic or pixie dust. It looks big and perhaps is a bit ugly. But what it may lack in looks it gains in performance. It’s large 12″ paper cone opens a window into the venue transferring the sound from your amp into music unlike most drivers you’ve already heard. It’s not picky about amplifiers either – which is uncommon since most full range drivers are. For me it achieves among the best sound I have heard in over three decades of DIY speaker building. As long as I can incorporate a helper woofer and tweeter, this would be my desert island driver.

beta-12lta-phase-plug

Dayton PS95-8 on Open Baffle

Dayton PS95-8 on open baffle

Dayton PS95-8 on top of H-frame

I really enjoy this driver. It’s not the flattest measuring or most neutral but it’s very enjoyable, especially for Jazz and Classical. For vocals, there’s a touch of sibilance which may bother some listeners. To reduce this, angling the baffle away from the listener is important. If you are a Spotify listener, you are particularly in luck due to their new EQ.

My system consists of:
• Amp: SMSL SA50 (digital)
• Bass: H-frame (Eminence Alpha 15 powered by Dayton 100 watt subwoofer amp)
• Source: iPad 2 streaming iTunes Radio @ 256kbps or Spotify @ 160kbps
• Room: 24′ x 12′ (moderately furnished, two couches, tv, etc.)

The first thing you will notice when hearing the PS95-8 is the rising treble response. You will also notice how detailed, fast and sweet sounding it is overall.

I’m not a driver designer but the PS95-8 looks beautiful and is beautifully made. The performance backs up its looks too. This thing has excellent detail with solid midrange performance. It’s an extended range driver that competes with anything and everything at approximately the same size regardless of price and makes a great main driver in a high resolution system. I like it on open baffle with help on top and bottom.

Placed in the center of a 19″ x 19″ baffle and sitting atop an H-frame completes a very nice combination. The result is a beautifully expressive and lively sound. Since a tweeter is unnecessary this combination can be considered more of a purist full range system – as long as you don’t consider bass support as spoiling the deal. This speaker sings!

Compared to Fostex drivers, the little Dayton PS95-8 has a personality of its own. It’s more cheerful in its approach. It has a happy sound. But after listening for extended periods the sibilance on vocals begins to become bothersome. It’s got a peak at about 15kHz. The venerable Fostex 127e has a peak at about 7kHz. Both drivers are bright but have peaks at different frequencies. Ultimately, the Fostex has more of a lisp while the Dayton has more spit. Fortunately for the Dayton, Spotify has an equalizer with a frequency lever at 15kHz. Simply sliding it down about halfway reduces sibilance making this driver wonderfully musical and very listenable for long periods.

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Spotify equalizer provides control at 15kHz to help reduce bright sounding speakers. Please add 4.7kHz and 7.5kHz for even better tuning.

Interestingly, I don’t notice any sibilance on instrumental music and can listen for hours with or without the Spotify EQ. But Norah Jones and Diana Krall sound too spitty without EQ to me. It’s all of the other wonderful qualities this driver has like ghostlike imaging, expressive midrange and an overall fun and enjoyable sound that prompt me to continue listening and tweaking it. Honestly, I had retired the driver until discovering the new Spotify equalizer. If you listen to Spotify the equalizer’s 15kHz lever is all you need to reduce the 15kHz peak and enjoy fatigue free music all day with the Dayton PS95-8.

Overall, this system sounds top notch and this inexpensive little wonder is one of my personal favorite drivers even tho it has one fatal flaw. If you like a bright and lively sound and don’t mind a bit of sibilance, the $25 Dayton PS95-8 is a great deal. If you prefer a flatter, more honest sound and listen to Spotify, adjusting the EQ down at 15kHz transforms the PS95-8 into one of the best full range drivers I’ve heard regardless of price.

Vifa TC9 plus helper tweeter on Open Baffle

Vifa PC9 on Open Baffle

Vifa PC9 on Open Baffle

The Vifa TC9 is a great driver regardless of price. It’s claim to fame is neutrality and flat measuring frequency response. As a full range driver it ranks highly among the current crop of competitors. As well received as it is, on an open baffle and in my system, I feel the Vifa could use some help in the treble so I opted to add a helper tweeter and see if it satisfies my 49 year old ears even more.

My system consists of:

  • Amp: SMSL SA50 (digital)
  • Bass: H-frame (Eminence Alpha 15 powered by Dayton 100 watt subwoofer amp)
  • Source: iPad 2 streaming iTunes Radio @ 256kbps
  • Room: 24′ x 12′ (moderately furnished, two couches, tv, etc.)

I’ve already listened critically to the Vifa TC9 and enjoyed it very much, but to my ears the high frequencies are a bit recessed.

I have lots of unused drivers in my collection and decided to rummage thru my colleciton. Over the years I’ve purchased drivers from Parts Express and Madisound that I never use. After initially examining them many stay boxed in the closet. But I label the boxes and one said “Jamo tweeters”. I believe I purchased these for $5 each from PE. They were wrapped in cardboard, face to face. I removed them hoping their European flavor would suit the little Vifa well. I wasn’t wrong.

I’m not really a fan of dome tweeters. I think it’s because many commercial designs using them (most) allow the dome tweeter to play too hot. Domes have a fizzly, chuffy sound I find artificial. I was able to easily reproduce this. Determined to treat the Vifa TC9 like all of the other full range drivers I’ve used over the years I connected a .47uf capacitor on the positive terminal of the Jamo dome tweeter. Placing the baffle on top of the H-frame and firing up iTunes Radio I knew immediately I was on the right track. The treble of the Vifa filled in and I no longer had to listen for it. So I sat down for some critical listening and heard that fizzly dome sound. A steeper slope on the crossover first came to mind, “Where are my coils?”, I thought.

The fix was even simpler. A .33uf cap replaced the .47uf. At first, my ears strained to hear the tweeter at all, but covering it up with my hand then removing it revealed its lovely contribution to the overall sound. To my ears, the blend was seamless.

One of my favorite full range drivers is the Dayton PS95-8. It’s frequency response is balanced from about 200Hz to 10kHz where it peaks in the treble. Several strategies can be used to reduce or eliminate this peak.

  1. Reduce the peak with a circuit
  2. Add a crossover and a tweeter
  3. Angle the driver away from the listener
  4. Don’t use this driver

I chose to angle the driver away from the listener and this works well. I tilt it upwards at approximately 30 degrees. But the overall performance of the driver is never perfectly flat – it’s flattish. It also has a bit of sibilance which, for me, is its only flaw. My two teenage sons disagree on which driver is better. My older son claims the Dayton PS95-8 has a ’rounder, larger and more lively sound’ whereas my younger son feels the Vifa PC9 sounds more lifelike. Personally, I’m torn. The Dayton is great at filling a room with lively sound but with a touch of sibilance while the Vifa sounds more natural to me on vocals. The image the Dayton throws is larger than the Vifa which is probably why my older son prefers it. Both drivers are top notch – sound different – and worth hearing if you are seriously considering them for your main system.

The Vifa TC9 is similarly sized but does not have the treble peak. This lack of treble energy is this driver’s downfall. The dome tweeter fixes this beautifully.

Note: The Jamo gels with the Vifa like no other tweeter. I tried two dozen dome tweeters from various manufacturers. None approached the synergy with the Vifa as the Jamo. Just kidding of course! I believe any dome tweeter can be used successfully with the Vifa TC9. If you have some lying around, try them. Perhaps the best match would be one by Vifa? Perhaps a ribbon tweeter would sound even better? I leave that up to you.

Once I decided on a .33uf capacitor (that’s it) coming off the positive terminal of the dome tweeter I sat back in an Ikea Poang and marveled at the sound. This speaker was reminiscent of the sound I heard in Hi-End audio salons like Lyric Audio, Park Avenue Audio and the used Hi-End dealer I used to frequent on Long Island. I’d describe the sound as pristine, detailed, full, rich and neutral. Vocals float in space – I attribute this to the Vifa TC9 being on an open baffle. Bass is awesome – I attribute this to the H-frame. Treble is perfectly acceptable, especially when compared without using a tweeter at all. The tweeter enhances the TC9’s treble without overpowering or calling attention to itself. Treble sounds like it’s coming from a nice dome tweeter – this I attribute to the Jamo. The overall presentation from top to bottom is great!

My setup allows switching new baffles in and out easily. The baffle with the Vifa / Jamo is probably the most refined, accurate and neutral sounding speaker in my collection. I consider it a reference because of the Vifa’s known, and excellent, measurements. Only the Vifa’s extremes are ‘enhanced’ making this fine sounding “full range” driver a critical part of one of the best speakers I’ve ever heard.

Open Baffle on top of H-frame

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Open Baffle featuring 3″ Dayton PS-95-8 on top of H-frame 

The H-frame makes great bass. Thanks to MJK’s wonderful H-frame design I’ve been able to enjoy open baffle bass in my home. It also makes a great speaker stand. I’ve placed small sealed and ported speakers on top (and enjoyed the sound) but decided to try open baffle with my growing collection of full range drivers.

I enjoy full range drivers for their coherent, crossover-less sound. I was pleasantly surprised how good they sounded on a simple open baffle. This has been my setup for the past few years and its provided a very enjoyable listening experience.

Following the basic formula MJK outlined in his H-frame + Jordan project with just a few modifications proved successful. While MJK chooses to administer crossovers on the woofers I take an easier approach using a typical subwoofer amp to dial in the bass. MJK incorporates a cutoff frequency on the full range driver where I simply run them without filters. With my approach the baffle size (18″ x 18″) naturally rolls off the full range driver of your choice somewhere around 250Hz. Feel free to include circuits for an even steeper bass rolloff and additional protection. An inexpensive option is to use a single 200mf capacitor wired to the positive terminal of the full range driver. This will reduce bass frequencies another 6db per octave from about 150Hz and below. Although I understand the benefits of filtering out bass I’ve yet to blow a driver and do not hear any distortion. In fact, the driver barely moves in my setup. Additionally, the idea of running the wire directly from the amp to the driver is appealing. Steeper filters consisting of caps and coils can be used but require more expensive components that cost more than many full range drivers.

Sample of 3″ drivers naturally rolling off on an 18″ x 18″ baffle. Larger diameter drivers will roll off at approximately the same frequency.

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Once you’ve built your H-frames position them where you like and listen. Modify the placement if necessary and mark your spot. Although many suggest two to three feet of space from rear and side walls sounds best I found that just a foot or foot and a half works good too.


In this chart I’ve included the Eminence Alpha 15 response on open baffle (pink line). As you can see the Alpha 15 is much more efficient than the 3″ drivers. I’ve taken the liberty to show what I believe is happening once the Alpha 15 is connected to a subwoofer amp with Gain and Frequency controls. Using Photoshop, I created the adjusted curve (blue line).

Since I enjoy rolling drivers a way to swap different baffles was necessary. I devised a handy stand. A wooden lip in front and a cinder block in back enable easy angling for best sound.

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The baffle is simply a 19″ x 19″ square with a hole in the middle. Offset the hole if you feel it will sound better. Personally, there are so many room variables that I don’t think offsetting the driver will sound much different – for better or worse. But feel free to experiment and do what you feel comfortable with as a DIY speakerbuilder. In addition, there’s no need to concern yourself with driver specifications (for example, Qts, Qms, Vas, etc.) as needed for sealed, ported or back horn designs. Just screw your favorite full range driver onto the baffle and you’re good to go.

So how does it sound? Excellent! Fortunately, all the calculations and math have been done for us thanks to the mindshare on the internet. The H-frame is a brilliant design that maximizes bass quality and quantity. Its size vs performance ratio is better than anything I’ve heard. Large bass bins or back horns don’t need to live in your home – unless you want them there (they do have their own advantages of efficiency and dynamics that are tough to beat). The H-frame does require a good amount of floor space so this is an admittedly large speaker. But the sound is beyond reproach and very musical, in my opinion. Mini monitors plus powered boxed subwoofers just don’t sound as realistic. Any type of large boxy speaker cabinet just sounds different – although there are many different ways to build a great sounding speaker. Open baffle is more my cup of tea at the moment. I just prefer the sound they produce.

Open baffle speakers have the following sonic characteristics:

• Wide soundstage – orchestras sound BIG
• 3D imaging – instruments and vocals float in space
• Natural tone – no thumping bass or boxy colorations
• Space between instruments and vocals – there’s more ‘there’ there

I like traditional boxed speakers and have a great set in my bedroom but because of their limitations I listen to them less critically than I do open baffle.

Once setup properly, open baffle designs just let you enjoy music played thru your favorite full range drivers.

If you are interested in learning more about open baffle and full range drivers I highly recommend building an H-frame plus open baffle system. From one audiophile to another – one music lover to another – I predict you won’t be disappointed.

A Case for Cheap Digital Amps

Digital amps - big sound comes in small packages. Aragon and Topping amps

Digital amps – big sound comes in small packages. Aragon and Topping amps.

I’m an audiophile. I love good sound and I love the gear music is played thru. Sometimes I find myself enjoying the gear more than the music. That’s when I put on different music! Over the years I’ve had the pleasure of owning several amplifiers – some good and some not so good. I’ve owned the three amps pictured above (specifically, I owned the Aragon 2004 mkII (the 4004 is pictured), Topping TP21 and Cary Audio SLA70 mkII). These amplifiers represent excellent values in Hi-End Audio. The Aragon is solid state and cost over $1,200 new. The Topping is digital and cost under $100 new. The Cary is tube and cost nearly $2,000 new. They all have their own sonic signature – but which is best?

SMSL, Dayton and Topping make quality digital amps

SMSL, Dayton and Topping make quality digital amps for under $100

I believe digital amps will change audio because they are inexpensive, small and sound amazing!

SMSL digital amp beside a Cary Audio tube amp

SMSL digital amp beside a Cary Audio tube amp

When the Sonic Impact amp came out sometime in 2004 it impressed audiophiles all over the world. Blind tests were arranged where the little digital wonder sounded better than amps costing over $2,000. Today, there are several manufacturer (predominately in China) churning out these little sonic gems. There’s almost no way to get one that doesn’t sound great.

The original Sonic Impact amp was later replaced by the Dayton DTA-1

The original Sonic Impact amp was later replaced by the Dayton DTA-1

My favorite brands are SMSL, Dayton and Topping. Unfortunately, they all feel a bit cheap compared to my multi-thousand dollar Cary tube gear but certainly acceptable for the price. I love them all!

The SMSL is my favorite. Rated at 50 watts it sounds the most dynamic and gets the loudest. It’s pretty much the best sounding amp I’ve ever heard even with a touch of sibilance (which could be my speakers or source – an iPad streaming iTunes Radio). Bass, midrange and treble are all fantastically detailed and dynamic. It compares very favorably with my Cary gear. This is an amazing amp!

The Topping is a little underpowered and requires more efficient speakers than the SMSL. Otherwise it also sounds great. It might have a bit of a softer, less dynamic sound but that may be due to its 25 watt rating. I think it’s even less (my Cary gear is rated at 30 watts and plays much louder).

The Dayton is also rated at 50 watts and gets plenty loud with any speaker. The sound is just as incredible as the other two digital amps. The only problem I had with it was the left and right channel were not balanced at very low volume. Turn the volume up and everything balances out perfectly.

Digital amps sound better than solid state based amps. They remove the grain, flat imaging and dryness only the best solid state is capable of reproducing. To me, most solid state (regardless of price) share similar shortcomings. Tubes sound great but have their own issues. My Cary gear sounds warm and rich but is plagued by hiss and occasional clicks. The tubes must be changed every three years and during that time you never know when a tube will fail. When that happens it’s difficult to enjoy your music. When everything is just right the Cary’s sound wonderful. With digital, if something goes wrong you throw the amp away and buy a new one. I keep a spare in my closet. The original Sonic Impact (and shortly thereafter Dayton equivalent) kicked off an amazing beginning to a bright future for excellent sounding music. In my opinion, digital bridges the gap between solid state and tube. It captures the best qualities of both older technologies. If I knew that these inexpensive and great sounding amps were coming out around the turn of the century I’d have saved my money. I highly recommend my fellow audiophiles (who may be hesitant) purchase a digital amp and setup another system to enjoy. Put it in the kitchen, the bedroom or the basement. Then, when you have time and feel so inclined, swap out your big amp for the digital. Forget about price, size and weight. Hook up your cables and hear what I’m talking about.

Wild Burro Betsy WOW Wide Range Driver

Wild Burrow Betsy WOW on Open Baffle

Wild Burrow Betsy WOW on Open Baffle

The Betsy WOW (WithOut Whizzer) is an interesting and unique driver. Fortunately I purchased a pair several years ago when Wild Burro Audio Labs was just starting out. Since moving into a small two bedroom apartment, I’ve been experimenting with fullrange and wide range drivers on open baffle and the Betsy WOW finally made it onto a baffle – along with a piezo helper tweeter.

betsy-wow-frequency

Betsy WOW frequency response

The baffle is 18” x 18” and should provide response down to the 200Hz to 250Hz range as per Xlbaffle software by Thorsten Loesch. A wonderful H-frame (designed by Martin King) provides bass support powered by a typical subwoofer amp.

The Betsy WOW is a dynamic driver! Music has an extra push when played thru it. They are forward and slightly in your face. To ameliorate this I simply angle them about 20 degrees away from the listening area. The piezo circuit is an 8 ohm resistor across the terminals with a .67uf capacitor on the positive terminal. This adds the missing sparkle and air and extends the frequency response past 20kHz. Perhaps a .47uf capacitor will further reduce the forward sound? This will be a matter of taste.

The Betsy excels with Classical and Jazz. Many late night sessions proved very enjoyable. Details are clear and the soundstage is large. Some drivers tend to mask the details in Classical music, not the Betsy! Because of the way it’s voiced, Classical music sounds huge. The orchestra sounds large and you can hear/feel the presence of the instruments. Strings swell in volume producing goosebumps. A sax can sound scarily real – including the breaths in between notes. Jazz becomes a dynamic experience with lots of punch and authority. Percussion is fast and impactful. Instruments retain their distinct character and are very recognizable. If I mostly listened to Classical and Jazz the Betsy might be my favorite driver. Certainly, I play more Classical and Jazz when listening to the Betsy than I would with nearly any other driver in my collection.

Overall, the Betsy WOW could be the most interesting driver in my collection. It’s not fullrange but it’s extended enough to easily supplement with a super tweeter of your choice. Or you can purchase the regular Betsy with a whizzer and get your treble that way. The Betsy is one of the reasons I enjoy listening to 8” fullrange drivers (many of my fellow DIYers prefer smaller diameters). The Betsy is efficient (rated about 92db per watt) and it certainly plays loud with just a few watts and sounds louder than most of the drivers I have, including the Fostex 168 which is rated higher at 94db per watt). I highly recommend the Betsy to Classical and Jazz music lovers looking for a dynamic, detailed sound with a large soundstage. As I type, it sounds like violins are in the room with me. I can practically hear the rosin on the bow!

Update: 

I decided to keep listening to the Betsy WOW. It’s a euphonic driver and the most romantic driver in my collection. It exaggerates the upper mids creating a forward sound on Pop and Rock. I wouldn’t describe it as bright but the mids certainly stand out. Male and female vocals sound a bit chesty but once your ears adjust you find the Betsy grabs hold. Flatter measuring speakers sound different but the Betsy allows an intimate view into the musical venue. Ella Fitzgerald sounds like she’s singing a bit too loud compared to the band but this type of presentation can become addicting.

If you’re into a lush, forward upper midrange and enjoy a large soundstage then the lively and dynamic Betsy is for you. I found I couldn’t wait to get home and play music.

The Betsy WOW is a worthwhile acquired taste.

Fostex 168z – A Wonderful Full Range Driver

The Fostex 168z (older style with whizzer) is one of my favorite full range drivers. I’ve tried it in several cabinets but enjoy it most in a large ported box. It has a midrange heavy sound but when you bring the bass in line with the midrange it sounds beautiful. It doesn’t need a tweeter on axis but I prefer the sound slightly off axis and with a rear mounted tweeter.

Fostex 168z in Large Ported Box (42L)

Nagoaka Tetsuo designed a 46 liter cabinet for this driver and even tho it doesn’t simulate very well (not flat) it sounds great! Years ago I built the 46 liter cabinet but lost them during my divorce. Fortunately, I came across a pair of large AR cabinets left out for trash, brought them home and refinished them. You can see the shape they were in. With a little elbow grease I was able to restore them. They look great sitting in the corner of my apartment. They are 42 liters but certainly close enough. They are tuned to 59Hz.

As for the sound, it’s just as I remembered. The bass really bounces along. It’s full and rich without any strain. They are not perfect but always make me smile and produce an engaging sound. It’s a bit full in the bass (which can be adjusted to taste with more stuffing) but everything else is wonderful up until the treble where they roll off. I may put a tweeter on the rear to add extra sparkle. Otherwise, these are great examples of how a full range driver can sound in a simple ported box. If you already have these drivers, or come across them used, I can’t recommend them highly enough in large ported boxes.

unfinished-box-foxtex168z

finishing-large-box-fostex168z

fostex-168z-finished

Fostex_168S_Box_Plot-copy

fostex-168z


 

Fostex 168z in a Back Horn (BK161)

My son, Jeremy, standing beside a not too successful back horn project.

Pros: Jump factor, big sound.

Cons: Hollow sounding, impossible to move around due to the MDF construction and sand filled voids. I’ll never do this again.

Fostex-168sigma-bk161

 


 

Fostex 168z in a BIB

Much better sounding than the back horn above. The BIB sounded great in corners retaining all of the drivers positive traits. It’s certainly one way to go with this driver but I prefer the large ported box because it’s smaller and has a bouncier, more fun bass. The BIB is dryer sounding and probably more accurate (flatter).

168z-BIB

My boys, Jeremy and Jason, helping me build a BIB!

Jeremy-Jason-Bib

 


 

Fostex 168z in Ported Box (24L)

It sounds good up against a wall or in a corner but never fully satisfies since bass extension isn’t great. It’s ok and can be satisfying but does not allow this excellent driver to reach its potential. Build it if you lack space and can’t build the larger box otherwise, I’d say the overall performance is only average. The box is tuned to 62Hz.

1197-127e-168s

 


 

Fostex 168z on Open Baffle 

Certainly a good performing speaker. It satisfies on many levels but can sometime sound dry. Although I like this speaker I still prefer this driver in the large ported box. Here I have mine set up on top of H-frames (Alpha 15). Just about anything sounds great on top of H-frames! The baffles are 18″ squares. Using Thorsten Loesch’s Open Baffle Spreadsheet (speakers two feet from the rear wall) my simulations predict a rolloff around 250Hz (the red line is for the Fostex 168z). Clearly there are better choices for open baffle but I was curious and happily listened to these for months before taking them apart.

OB-freq-18x18-baffle fostex-168z-open-baffle