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My Pensil 6 build.

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Hi all,

Finally decided to have a go at a DIY speaker build and the the Pensil seemed about as straightforward as it can get. I've read quite a bit about the build and setup on here, so thanks to everyone already! :)

I decided on the Pensil 6 with MA Alpair 6m drivers, based upon the size of my room and the description of the driver characteristics.

My room is a newly set up den for me and the kids to use for music and TV. We've got about 3.5m x 3m with suspended timber floor. The speakers fire across the room, so there's about 2.5m between speakers and ears.

den.jpg

The current setup:

setup.jpg

I chose the drivers because they promised a more laid-back sound that's OK for use with low-cost sources. I'm planning to use a Topping TP20 mk2, driven from the TV analogue output (i know :eek:).

topping.jpg

The current setup (monitor Audio Radius 90s, plus passive sub) actually sounds pretty decent for the money I paid for it - nearly free! I just fancied building something for myself.

Build photos to follow...


Martin
 
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Well that was quick and painless...

pensil1.jpg

Birch ply custom cut by a company on ebay UK. Only £66 delivered :eek:

pensil2.jpg

I could never have got it so square if I'd cut it myself. Cabinets were glued and clamped, not screwed.

Pensil3.jpg

Rebate for Alpair 6M driver - ready for the hole to be cut with 95mm holesaw.

pensil4.jpg

Batten added to allow the backs to be removeable.

pensil5.jpg

Speaker terminals from ebay. Not sure what to use for internal wiring :confused:


Just waiting for the holesaw, and we're ready to go. Gonna buy a pair of pillows for the stuffing.

Should be ready to fire up in a day or so.

Martin
 
Founder of XSA-Labs
Joined 2012
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Good deal on the precut BB - does that include material cost and delivery? If so, an absolute deal and great for those without a shop.

Nice work on assembling it. I think many folks use single strands of 24ga solid copper from CAT5 cables. At the drive levels that full range drivers get - works very well. Cheap 16 gauge lamp cord or power extension cords work well too - way over sized and good for driving hundreds of watts.

What is predicted f3 bass extension of A6 in a Pensil?
 
Depends on how much damping you use -the point of the pensils (all of them) is that I designed them to be user-adjustable via the stuffing density. In the case of the Pensil 6, default anechoic F3 is about 55Hz with F10 in the mid 40s, but they sound like they have quite a bit more since I've juiced the alignment between 80Hz - 120Hz where the majority of LF energy exists. Tuning lower wouldn't be especially beneficial; I'm not a believer in pushing for maximum extension from little drivers, the harmonic distortion rockets as does excursion (short of a full-sized horn). Not a price worth paying.
 
Hi xrk971,

Yup, that price included everything. I just supplied the money and the dimensions :)

Thanks for the tip on the wiring - I've got some spare ethernet patch cables in the garage that i can cannibalise.

Hi Scott,

Thanks for the info (and the plans :D). I'm a noob, but i guess F3 and F10 relate to the -3db and -10db rolloff frequencies?

I'm planning to use my Monitor Audio Radius active sub to fill in the lower frequencies.

Cheers,

Martin
 
I read Earl Geddes advocated using lots of dowels to brace the inside with, adds stiffness but I guess doesn't resonate as a braced panel would. Dowels going in both directions. I think anything would help? Random pieces in random places should help to break up standing waves, or would this mess with the pensils port loading?
 
Nice find on the precut ply! Very cool! I'd definitely recommend the bracing. Even on the smaller Pensils, those sides can vibrate quite a bit. I have the larger SuperPensil12 (original version) and did the large bracing as recommended plus additional bracing with dowels. Worked like a charm and got rid of all the panel resonances I was hearing (yes they were audible). Also look into lining the top with some sort of dampening as well as the polyfill through the cabinet.

Good luck and keep us appraised on how it goes!

Scott
 
Adequate in FR terms; not quite on the optimal pensil alignment, but reasonable enough. When Mark introduced the current generation Alpair 6 units I decided to discontinue the Pensil 6 as they're really a bit too small for this sort of thing & excursion is higher than I like. Given the TL damping, the load's quite unreactive & deflection behaviour is very consistent / linear though, so should still be nice enough in a small room providing they're not fed with uncompressed 1812 or HT, or cranked to high levels.
 
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I think we'll be OK, as we only listen at relatively low levels. I did consider the A7 version, but it's a bit too big for our space.

If it doesn't work out, I'll put them in some small cabinets for the office at work :)

Martin

p.s. the Pensil 6 is still shown on the MA website...
 
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Managed to get them all together this afternoon and have a quick listen.

Started off with loads of stuffing packed in and they sounded thin - obviously no bass.

Took out most of the stuffing (70%), leaving just a little bit at the bottom - sounded wierd, bloated, like an empty box. Not nice.

Put back half of the stuffing and they sound much nicer, but still thin sounding - no real body to the sound.

Switched on the active sub and its coming together now. Sub has the crossover at 80 hz.

I've not run them in at all yet, so volume levels are really low. How will the sound change with a few hours on them?

Slightly disapointed, but Will persevere to get them to give their best - any suggestions for me?

Cheers,

Martin
 
A few thoughts

Enclosure design - note Scott's comments on the Pensil alignment in general for the A6 size. I've heard all models of the 6 work quite well in several smaller enclosure for either near field ( including the Woden Stinger mentioned above) or HT rear surrounds - but it might simply be expecting a bit much from them a full size MLTL. A HP filter on them, in addition to powered sub, crossed over a bit higher ( 100-120 or so?) could help quite a bit.

Driver break-in - LF extension and overall dynamics could be expected to open up after the several hundred hours mark.

Amp - the smaller Toppings are nice enough little units, but even after full break-in the TP20 could be underpowered in terms of dynamic range for this driver.

Source - well, you said it yourself - the Alpairs aren't forgiving of lower quality resolution signals.

Room - if situated in same location as the stand mounts shown in opening post, you'll definitely need the sub.
 
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