Super Pensil Cabinets with TB W8-1808 Drivers - Thoughts?

[tlarwa]

So after a less than satisfying OB build attempt (not the bass response I wanted), I find myself with a $400 pair of Tang Band W8-1808 drivers. It has been suggested that the Super Pensil, while designed for the Mark Audio 12p driver, would also be a good choice for the Tang Band. Before I start a new cabinet build, I'd like to solicit other opinions, or see if it'll work well as is, or with modifications. Also, I have a pair of 6/4 hard sugar maple butcher block baffles (from the failed build) that are already cut for the TB's. Theyre plenty big enough for the Super Pensils, so 'd like to use them to give the speakers a different look. Any pitfalls with using a baffle of that thickness? The rest of the cabinet would be 3/4" BB, and I'd plan on incorporting the holey bracing scheme.

For the record, I listen to a lot of musical styles; prog rock, classic rock, jazz fusion, bop, acoustic jazz, singer-songwriter, etc. I want something that'll handle the lighter stuff but will also give me some mid-bass slam when needed. I'm currently running a set of modified Klipsch Forte II's, which definitely provide it. But I've been intrigued with single driver designs since I built a set of Fruglehorns a couple years ago (which used MA CHP70 drivers). Also, I'm in the process of moving to my first SET amp (probably a JEL SRPP 2a3 or SE KT88 design) and away from my rebuilt Fisher 400. Room size is 12' x 17', and it is treated.

Anyway, here are the specs of the Tang Bands:

PRODUCT SPECIFICATIONS
Nominal Diameter8"Power Handling (RMS)30 Watts
Power Handling (max)60 WattsImpedance8 ohms
Frequency Response45 to 20,000 HzSensitivity93 dB 1W/1m
Voice Coil Diameter1.5"
THIELE-SMALL PARAMETERS
Resonant Frequency (Fs)45 HzDC Resistance (Re)6.8 ohms
Voice Coil Inductance (Le)0.04 mHMechanical Q (Qms)1.33
Electromagnetic Q (Qes)0.66Total Q (Qts)0.44
Compliance Equivalent Volume (Vas)3.11 ft.³Mechanical Compliance of Suspension (Cms)1.28 mm/N
BL Product (BL)5.28 TmDiaphragm Mass Inc. Airload (Mms)9.43g
Maximum Linear Excursion (Xmax)5 mmSurface Area of Cone (Sd)220 cm²
MATERIALS OF CONSTRUCTION
Cone MaterialPaperSurround MaterialCloth
Basket / Frame MaterialCast AluminumMagnet MaterialNeodymium
MOUNTING INFORMATION
Overall Outside Diameter8.81"Baffle Cutout Diameter7.48"
Depth4.53"# Mounting Holes8
OPTIMUM CABINET SIZE (DETERMINED USING BASSBOX 6 PRO HIGH FIDELITY SUGGESTION)
Sealed Volume1.04 ft.³Sealed F387 Hz
Vented Volume3.27 ft.³Vented F347 Hz

Any input is appreciated. Thanks for your help!

Tom

 

[markaudio]

Hi Tom,
Pensil series box alignments are specific to Markaudio Alpair and CH series drivers. Installing alternate drivers into Pensil's won't work correctly.

I appreciate that you've likely not understood a larger issue: The Pensil series box designs are © copyrighted Markaudio. No permission has been given that agrees to the seeking of material that changes the Pensil design; Or the publication of such material that changes the usage of the Pensil design.

Moderators should step-in if or when this thread leads to a copyright infringement.

I've no wish to discourage you from experimenting, so I recommend you contact Tang Bang to enlist their technical support for a more familiar box design. Alternatively, members on this forum may be able to help you with a traditional box design that you can build from your salvaged materials.

Thanks
Mark.

 

[tlarwa]

Sorry!

Thanks for the reply, Mark. For the record, I in no way intended to knowingly infringe on your copyright. The Pensil design was suggested to me as a possibility for my drivers, so I was investigating it further. Had I not already had the Tang Bands and was building new speakers I'd definitely go with the 12p drivers. I used your CHP-70 drivers in my Fruglehorn build with great success. I'll investigate other suitable cabinet options that are proven for use with the 1808's.

Mods, please delete/close this thread and I'll repost under a different topic.

Thanks,

Tom

 

[markaudio]

Thanks for the reply, Mark. For the record, I in no way intended to knowingly infringe on your copyright. The Pensil design was suggested to me as a possibility for my drivers, so I was investigating it further. Had I not already had the Tang Bands and was building new speakers I'd definitely go with the 12p drivers. I used your CHP-70 drivers in my Fruglehorn build with great success. I'll investigate other suitable cabinet options that are proven for use with the 1808's.

Mods, please delete/close this thread and I'll repost under a different topic.

Thanks,

Tom

Hi Tom,
No worries, I realised you hadn't made any knowing action.
Thanks
Mark

 

[chrisb]

As with designs by Bob Brines, the Pensil series enclosures are proprietary designs following the general formula of MLTL - a format that with appropriate math, lends itself to use with a wide range of drivers - the 1808s certainly among them.

Indeed, someone may have already done the math - Bob certainly has done so for the 1772.

 

[planet10]

As said already the Super Pensils are unlikely to work with the TB because they are very driver specific. Nothing stopping you from designing a suitable ML-TL for the TBs thou.

It should be noted that the Pensil designs themself cannot be copyrighted, only the drawings and the name.

dave

 

[Bigun]

Try searching around a bit more.

Tang Band 1808 in MLTL
"Indeed I did run sims for a fellow for the 1808 in a MLTL. I liked ~100L which worked out to be a 48" tall box and however you want to work the CSA."

http://www.diyaudio.com/forums/full-range/213420-tb-w8-1808-mltl.html
"After trying many different configurations in mathcad I ended up with 80 liters internal volume cabinet that is 48" tall, 11.25" wide and 12.75" deep. I have read recommendations as high as 100 liters for a mltl box for the 1808 driver but it modeled fairly well in mathcad. It suggested a compensation network with a 2.5 mh coil and a 10 ohm resister in parallel. The stuffing specified was .5 pounds."

AFIK the super pencil has a volume of around 80 to 90 litres: http://www.diyaudio.com/forums/markaudio/236970-pencil-12-2p-pencill-plans.html

 

[Godzilla]

If I remember correctly, my calculations using WinISD resulted in a 3cf (approx 90 liters) ported box. I forgot the port dimensions but it was probably tuned to around 45Hz. I've never compared MLTL to a more square shaped box and wonder how different they might sound given the same volume and tuning?

That's a large box for an 8" driver but having used the 1808 in a 1cf (approx 30 liter) sealed box (Fs of about 95Hz) it's lacking bass and needs a subwoofer of some kind to sound its best.

 

[GM]

Any pitfalls with using a baffle of that thickness?

For the record, I listen to a lot of musical styles; prog rock, classic rock, jazz fusion, bop, acoustic jazz, singer-songwriter, etc. I want something that'll handle the lighter stuff but will also give me some mid-bass slam when needed.

The rear of the cutout needs to be chamfered to randomize reflections. Folks usually use a router, but the rougher, cruder, more irregular it is, the better. That, or glue felt or similar to it. Ditto the damping the frame, motor.

To get mid-bass 'slam' from a typical 'FR' driver requires a lot of acoustic efficiency: http://www.diyaudio.com/forums/full-range/173205-voigt-pipe-tb-w8-1808-a.html#post2296387

Unfortunately, I currently don't have access to my design programs, notes, etc., so can't provide any more details, but there's enough info to figure the rest out with MJK's software or 'slide' your way with Hornresp's 'Loudspeaker Wizard' if its size is acceptable.

GM

 

[planet10]

Our Monster miniOnken for the 1808 is 90 litres and these type of box tends to be smallish, so a well balanced ML-TL is likely larger.

dave

 

[GM]

I've never compared MLTL to a more square shaped box and wonder how different they might sound given the same volume and tuning?

The MLTL is more damped and if a low compliance driver is used, then it will tend to have more ripple in its BW due to the variable pipe damping not being able to control the driver as well over a wide BW, so best left for strictly either a ~two octave sub app or an acoustically large, well damped pipe/horn alignment.

GM

 

[Bob Brines]

I played around with the 1808 in a MLTL some time ago. It was 100l and 48" tall. The plot looked good, though.

Bob