Hello!
I have planned to built some simple fullrange loudspeakers during next months. I noticed that Pensil series louspeakers are quite easy to build and offer pretty good sound. But I have a problem; I don't know which model should I choose. Could you please give me any tips/recommendations which Pensil-series loudpeakers should I choose for small listening room (L=4.2m x W=3.3m x H=2.4m)?
I would use finnish plywood (birch) for construction material (density 680 kg/m3). Available thicknesses 15, 18, 21, 24 mm. Which one is best?
I have planned to built some simple fullrange loudspeakers during next months. I noticed that Pensil series louspeakers are quite easy to build and offer pretty good sound. But I have a problem; I don't know which model should I choose. Could you please give me any tips/recommendations which Pensil-series loudpeakers should I choose for small listening room (L=4.2m x W=3.3m x H=2.4m)?
I would use finnish plywood (birch) for construction material (density 680 kg/m3). Available thicknesses 15, 18, 21, 24 mm. Which one is best?
Depends on what you listen to & what you value sonically. If you like small ensembles, folk etc. & don't listen particularly loudly, one of the 4in models should do you fine. If you need greater SPLs / more dynamic range, then whichever happens to be the largest model that fits through your door. 
Depends on what you listen to & what you value sonically. If you like small ensembles, folk etc. & don't listen particularly loudly, one of the 4in models should do you fine. If you need greater SPLs / more dynamic range, then whichever happens to be the largest model that fits through your door.
Maybe I should go for the Alpair 10 or even 12 then, because I listen also hard/heavy rock music.
I prefer a little bit warm sound without any listening fatigue. I have successfully used open baffles with the combination of eminence alpha 15A + tangband w8-1808 drivers. They are based on MJK's worksheets and I like their sound a lot.It reads on the box plans that 18-20 mm ply is recommended. I guess it's ok if I use birch ply of thickness tolerance 20.0 -20.9 mm? It's the closest match.
Br
Arto
Thank you so far Scott!
Two more questions:
1) How much space is needed between Pensil 12 and side/front walls?
2) Can I listen in "near field" (~2-2.5 m distance between loudspeaker and listener)?
Br
Arto
Hi Arto,
Re your questions, we have small apartments here in Hong Kong. Several pairs of 12's are in corner spaces within 7 to 10 CM in corners of rooms. They play well. Likewise on listening distance, 2 to 2.5 M works fine.
Most of the guys here operate Alp12's in these smaller environments with lower power tube amps. In my case, one of Tony Wong's 8 watt 300B SET amps does a nice job. You like a "warmer" sound so I'd suggest a tube amp for your set up. Older MOFSETS and possibly some of the new class D's may also work but you won't need allot of power in a small room situation.
Also, check out your source component (CD player etc). Since you're closer to the drivers, they will reveal detail. You'll need a good component and descent quality music recordings. Not so critical for your rock music as outputs will be higher, but classical, female vocals, softer jazz etc will be will do well on Alp12's if the recordings are audiophile grade.
Scott may have more specific advice and information.
Cheers
Mark.
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From my memory its 46Hz for Pencil and 40Hz for Super-Pencil (these figs might be -3dB). Scott will know, think he's still on the Christmas hols.
Cheers
Mark.
...i'm curious about them too and would think the pensils are considered a air coupler so i'll guess it may be that you don't end up with vented box one note (bloat), bass?
Been waiting to hear from the designers, and please don't forget to include the aln dual column air coupler "Nessi" in that comparison.
I decided to build Pensil 12 cabinets. One cabinet is allmost ready. Hopefylly I will get first listening impressions during next weekend. I used 21 mm plywood with internal 23x23 mm strips to fix plates together with home tools. I think that cabinet is very rigid now. Bracings are maybe not needed.
I will maybe add additional 30 mm thick plate with spikes under the cabinet. According to my experiences spikes are very useful, but I will need an extra plate to fix M6-threaded inserts properly.
How about chamfering/filleting the front corners? Is it needed?
I will use Polyester stuffing inside the cabinet. How much stuffing is needed for Pensil 12?
I will maybe add additional 30 mm thick plate with spikes under the cabinet. According to my experiences spikes are very useful, but I will need an extra plate to fix M6-threaded inserts properly.
How about chamfering/filleting the front corners? Is it needed?
I will use Polyester stuffing inside the cabinet. How much stuffing is needed for Pensil 12?
Hi Kn,
Shouldn't be necessary to chamfer the corners. Add around 0.5lb (227g) of stuffing, adjust this material volume to suit your listening taste.
Post some pics - thx
Thx
Mark.
Hi Mark,
Based on the calculations, would the right amount of stuffing to be around 0.5 - 0.8kg?
Cheers,
Edwin
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Hi Edwin,
I used an online calc to get grams/Kg as Scott quotes imperial:
Answer: 0.5 lb = 0.226796 kg
But, lets ask Scott in case I've misunderstood his original spec.
Cheers
Mark.
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Some listening expressions after 5 hours of listening: very neutral and clean sound without any listening fatigue. Male/female vocals are awesome. Imaging is pretty good. Some piano tracks sound a little bit strange? Maybe too thin voice, not so full bodied as could be. Stuffing: 500 grams of polyester (polyfill) / cabinet. Setup: Arcam fmj cd33 cd-player and Vincent sv-236mk integrated hybrid amplifier. Setuo of Pensils: about 100 cm to front wall and 50 cm to side walls. Room: 4,2 x 3,3 x 2,4 meter. Listening distance >2m.
Which kind of setup you prefer? How much toe-in is needed?
Which kind of setup you prefer? How much toe-in is needed?
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Hi Knight Rider,
Looks like a very nice build. Its too soon to judge your speakers. Give the Alp12's at least 100 hours of gentle run-in. Looking at your pics and room and taking your listening distance into account, I'd suggest a slight toe-out of around 5 to 10 degrees. But you'll need to further experiment once the driver's have run gently for at least 200 hours.
Re piano, you'll to check the quality of the recordings. Your're getting good vocal but challenges with some piano leads me to suspect source quality. All sources and recordings will be 100% scrutinised by the Alps. I well remember having to hunt for the Nonesuch version of Górecki's 3rd sung by Dawn Upshaw. I bought a different recording prior to buying the Nonesuch, took me Only 3 minutes to throw into the bin! I know Górecki's 3rd well having attended concerts in London and Birmingham. Don't assume that all CD's (or vinyl) recordings are good.
Recording Górecki's Third Symphony in London, May 1991 | Nonesuch Records
Last year, I made Alp12/Pencil 12's for respected pianist John Morris. He runs Alp12's in Japanese Walnut Pencil 12 cabs, fed by a Luxman L-590-A11 int. Class A amp and a Luxman D-06 CD player. John chose this combination after many hours of listening. I spent time helping John to set up his system using my collection of Murray Perahia (mainly Naxos) CD's. John's room is fairly large (from memory 9m X 6m)
In my studio, I use Japanese White Birch wood Pencil 12's on Accuphase 308 Int. Class A/B amp and an Accuphase DP67 CD player. The Alp12 drivers in these cabs are well run-in, nothing "thin" in their sound.
In the long run, I think you'll need to do some experimentation. I'm not 100% sure if the potentially powerful Vincent is the ideal amp on your system given your listening distance is relatively close and room size is slightly tight for these big Pencils. I'm not certain how the Vincent's auto switching between Class A to A/B will effect the drivers. From what I can see Vincent and Shen Ya share technology and possibly components? If they do, its not necessarily bad news but most amplification in this sector of the market is geared to "commercial" reality. Design and component selection will be affected by this factor.
I'd also be tempted to keep a look out for a separate DAC if you intend keeping the Arcam. Good it is, but not quite in the class needed to make the best of the Alp12's. I personally only use CD players with dedicated or in-house made transports. Sadly, this means spending allot more money as yet I've found no short cut that satisfies my testing needs.
That's the beauty of DIY. It gives you the opportunity to experiment and build a great system over time.
Cheers
Mark.
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