Studio 101 mkII
Copyright 2019 © Troels Gravesen

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DRIVERS   CROSSOVER   CABINET   WORKSHOP PICS   MEASUREMENTS   SPEAKER-KIT   CROSSOVER LAYOUT

Making an mkII version of the popular Studio 101 has been on my to-do list for a long time. The Studio 101 has sold steadily over the years and here's an updated version with an updated 18W woofer, better tweeter and optimised crossover.
There are classic drivers that don't change much over the years. The 18W/8542-00 is such a driver featuring a cone similar in composition to my 8008-HMQ driver. The 18W/8542-00 has gotten a brush up since last time, new alu chassis, a more thorough coating of the surround and damping of the center pole piece producing an overall flatter response and smoother roll-off. Overall the edge coating suggests some experience from the 18WE driver is carried over to this driver. All very welcome. Now 18W/8542-10.
I've praised the D2608/913000 tweeter before, and this tweeter in terms of quality belongs in one of the higher categories among ScanSpeak tweeters. Here's a test of the D2608/913000 tweeter and compared to D3004/660000 tweeter. Link here.

In had high hopes for the 18W/8542-10 and I wasn't disappointed. Kind of sound I'd gotten used to from the Ellipticor 18WE driver. Not as extended as the 18WE driver but this can sometimes be an advantage depending on what type of crossover we use. What matters is that there are no peaks in the treble area than interferes with tweeter performance. The dip at 4.5 kHz doesn't matter being one octave above point of crossover. Dips can be very hard to hear contrary to peaks and here we are not in any trouble zone.

I know the 9130 tweeter very well from other constructions, so no surprise here. Transparent and smooth treble performance. Coming from the Ellipticor-3 takes some mental adjustments as we just don't have some 500+ sqcm membrane area for bass, but we get used to it. Not having the deep bass will focus our attention to midrange and treble and they better deliver. I many ways it's harder to make a small speaker than a big one. It takes careful fine-tuning all over the frequency range.

I have tried combining the STUDIO 101 mkII  with a 10" Faital 10RS350 bass driver in a vented 34 litre cabinet driven by a Hypex FA251 and it all of a sudden turns the speaker into a powerful 2-way + sub. The 18W/8542-10 can handle quite some power and again, like the ATELL-3, I have decided not to ad any high-pass filter to the driver. I has its benefits. The FA251 can be driven from the speaker cables, so no line signal needed, only an extra power cord. Go to bottom of page.


Click image to view large

Basics:
2-way speaker from 7" midbass and 1" dome tweeter.
Crossover: 2nd order LR2
Dimensions: 22 x 30.5/34.5 x 42 cm, WxDxH.
System sensitivity: 86-87 dB/2.8V/1 meter.
Impedance: 8 Ohms, minimum 6 Ohm at 4 kHz.
Point of crossover: 2300 Hz.
Power requirement: 20+ watts/channel.
Power handling: 100 watts. Please also read: http://www.troelsgravesen.dk/power-handling.htm, and remember any burned driver is a misused driver.

Useful links:
http://www.troelsgravesen.dk/tips.htm
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/LCR-RC.htm

FAQ:
You cannot change cabinet front panel dimensions and drivers' placement without needing a new crossover - and I cannot help.
You cannot use any other drivers with the crossover shown here.
Please read these files before e-mailing:
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/choices.htm


DRIVERS
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Click images to view large

  Download specs here: 18W/8542-10    D2608/913000

(the terminal marked with grey paint on the 9130 tweeter is PLUS)


Seems the 8542 has gotten a ring of coating/damping material to increase mass at the transition from cone to surround.
On top of this a full-cover coating of the foam surround. The surround is also coated on the rear side.
Finally the center pole piece has gotten a felt pad, improving the high-frequency roll-off.


CROSSOVER
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Those familiar with the mkI version may notice a simpler crossover for the 18W/8542-10 driver. Link to mkI. Here we feature a simple LR2 filter. Due to the advanced edge coating of the new 8542, we don't have any upper-mid bump we need to eliminate with a notch-filter and the inherent roll-off is nicer compared to the old 8542. R4 shapes the 8542 roll-off together with L2 and R5 and C2 takes care of a little too much energy in the treble range.
Tweeter crossover is simplified too, eliminating an RC circuit. A simple LR2 filter creates the target roll-off.


CABINET
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Click image to view large

Cabinet almost as simple as can be. Rectangular box with one vertical brace. Front panels made from 20 mm MDF/HDF. You can make the cabs from 19-22 mm HDF/MDF or 20 mm Baltic birch. If you use 22 mm overall increase depth by 10 mm.
Port can be to the front or the back. If I put it one way, I immediately have the question whether it can be the other way, so the choice is yours. Port is Ø68 x 220 mm. Fairly big, but I think 50 mm is too small. Better too big than too small to prevent any port noise.
Outer front panel: Chamfer driver hole 45 deg. to ~12 mm depth. Inner front panel, route 182 mm hole and chamfer ~12 mm depth.

Cabinet damping:
Add 4 mm bitumen pads to sides, top and bottom panels. Se image below.
Add 8 mm felt to sides, top and bottom panels. See image below.
Fold a piece of 50 x 12 cm acoustilux and place behind tweeter against top panel.
Passive version: Add two layers of acoustilux 50 x 20 cm op top of crossover on rear panel and against top panel.
Active version: Cover rear panel incl. Hypex box with felt material. Add one layer of acoustilux agaist rear and top panel, 20 x 50 cm. Make sure it doesn't obstruct air flow to the port.

As always: Any change to front panel dimensions or drivers' placement and you need a new crossover - and I can't help.


Workshop pics:

I just love building small cabinets !


Making braces, holes Ø165 mm.


Cabs were assembled with tape alone. Make sure corners are right-angled. Use strong flexible tape if this is what you do.
All outer panels were given a thick layer of lacquer before cutting to size. This prevents - to some extent - edge ripping and it prevents excessive glue penetrating the outer layer of veneer and making spots in the final finishing.


I had trouble with one cabinet not being right-angled, thus the above arrangement during curing. Just needed a 1 mm squeeze.


Routing for the port - and front panels pretty much finished.


Left: Bitumen pads in place. Use vinyl glue. Right: Felt in place. Fasten also with vinyl glue.
Disregard the fillets at corners to the front. I had to use the cabinets for more front panels.


Crossover mounted on rear panel. Add felt above crossover on rear panel.


Cut a piece of 16 x 50 cm Acoustilux and place toward top and rear panel as seen on photo.
Cut an fold a piece of 14 x 50 cm Acoustilux and place around port as seen on photo.
That's all for damping.


MEASUREMENTS
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A few comments on MEASUREMENTS before you start interpreting the readings below.
First of all, if we think measurements will tell us how a speaker sounds, we're wrong. The perception of sound is way too subjective to be reflected in any measurements we can perform. A loudspeaker system is meant to give us a satisfying idea of an acoustic event and for some people a pair of 5 USD ear-plugs are enough, others spend 200 kUSD on a truly full-range pair of speakers - and the latter may not be happier than the former.
Measurements may give us an idea of tonal balance of a system, i.e. too much or too little energy in certain areas, although dispersion characteristics play a vital role here. A two-way 7+1 and a three-way 7+4+1 may display similar horizontal dispersion, yet sound very different. Measurements may tell us about bass extension if far-field measurements are merged with near-field measurements. In addition to this, ports may contribute to bass extension. Most of we diy'ers do not have access to an anechoic room for full-range measurements from 20-20000 Hz.  
What cannot be seen is what kind of bass performance we get in a given room. Bass performance is highly dependent on in-room placement of your speaker and the same speaker can be boomy in one place and lean in another. Actual SPL level at 1 meter distance and 2.8V input is useful for en estimate of system sensitivity and combined with the impedance profile may give an idea of how powerful an amplifier is needed to drive the speaker to adequate levels.
What measurements do not tell is the very sound of the speaker unless displaying serious linear distortion. The level of transparency, the ability to resolve micro-details, the "speed" of the bass, etc., cannot be derived from these data. Distortion measurements rarely tell much unless seriously bad, and most modern drivers display low distortion within their specified operating range. 
Many people put way too much into these graphs and my comments here are only meant as warning against over-interpretation. There are more to good sound than what can be extracted from a few graphs. Every graph needs interpretation in terms of what it means sonically and how it impacts our choice of mating drivers, cabinet and crossover design.
What measurements certainly do not tell is the sonic signature of the speaker, because speaker cones made from polypropylene, aluminum, Kevlar, paper, glass fiber, carbon fiber, magnesium, ceramics or even diamonds all have their way of adding spices to the stew. Nor do measurements tell what impact the quality of the crossover components add to the sound, from state of the art components to the cheapest of coils and caps, they all measure the same if values are correct, yet sound very different.


SPL of 18W/8542-10 on actual baffle. Green = no crossover attached. Red = from 1.8 mH coil. Easy driver!


Final system response driven from crossover.


Final system impedance. Basically an 8 Ohm speaker, 7 Ohms @ 200 Hz and min. 6 Ohms @ 4 kHz.


SPEAKER-KIT
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Level 2 is an absolute economy version, not revealing what drivers can really do.

All kit and component prices may be subject to change and are always to be confirmed by Jantzen Audio Denmark.

Download Complete Kit Sale Presentations (pdf file):

All technical questions to troels.gravesen@hotmail.com

All questions regarding purchase of kits, please mail Jantzen Audio at contact@jantzen-audio.com


CROSSOVER-LAYOUT
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Please read this file before mail: http://www.troelsgravesen.dk/LCR-RC.htm

 

Speaker wiring:

 


Potent bass module for the STUDIO 101 mkII
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During STUDIO 101-mkII construction I - for fun - placed a Faital 10RS350 bass drivers in my 34 litre test cabinets, gave them 2 x Ø68 x 220 mm ports and the plate-amp/DSP Hypex FA251.
The Faital driver can he had here: https://www.lean-business.co.uk/eshop/faitalpro-10rs350 (GREAT driver for 110 EUR). 10RS350 (8Ohm) datasheet here: 10RS350-8

See the finished bass module here.


 


Should you aim at more and deeper bass, try the ScanSpeak 28W/4878T01: 28W-4878T01.pdf

Have fun!