The Pencil: inspired by Ohm Micro Walsh Tall

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


Drivers: Peerless 832873 and Morel MDT-40 (tweeter).

Cross-over is just a 2. order Linkwitz Riley for the tweeter at 6 khz, 1,8 uF in series + 0,39 mH in parallel - Because the Peerless is ultralinear and has a natural rolloff at 6 kHz with 12 dB/octave rolloff

The enclosure is 10 liter, 71 cm tall, 12,1 x 12,1 cm internal.
The port (on the back of the speaker) has Ø 5,7 cm, length 10,5 cm.

The "tweeter-protector" on top is just a pencil-holder turned upside down :D

The costs is about US$ 500/euro 300 total for a pair. It's easy to build, and don't take up much space (except the sound, which is very spacious

The sound is fantastic - very dynamic, slam-bass, and a very natural soundstage. This is a speaker, where I don't skip music, but listen to music, I previously wouldn't have - THE PENCIL simply plays MUSIC... Try it, build it.

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


Regards, Jesper
 
Looks great. I built some speakers firing upwards with a deflector cone above it and a tweeter above that . Pity I have no pictures . It was made for a friend in the 80's and I guess the unit isn't alive anymore.
Maybe you should have a grille perforated like the tweeter , for the mid/bass also .
Theses kinds of arrangements do give a very spacious sound but if I remember correctly , it didn't give a rock solid image like some standard speaker arrangements do.

Great job.:up:
 
Badge said:
I would have chosen a much lower X-over point, but that is a just my perspective. The MDT-40 is a good tweeter. I have a pair and my plan is similar but will use the B&O omni reflector approach.

Yes, the Morel is a very good tweeter. Not very fond of xovers in general, this is the most minimalistic I found useful. 6 db/rolloff is - in my opinion - not steep enough in general to protect tweeters properly . The standard xover-point in the 2-3 kHz range is generally bad, from an listening point of view (our ears are very sensitive in that area). So to create speakers where the crossoverpoint isn't audible, you'll have to either move upwards in frequency (as I do) - or down, which makes huge demands for the tweeters in 2-way systems.

But THIS Peerless bass/midrange is exceptional for this kind of speaker - a very wide frequency range, no peak at the upper frequency, and a natural and fine roll-off... See datasheet here
 
ashok said:
Theses kinds of arrangements do give a very spacious sound but if I remember correctly , it didn't give a rock solid image like some standard speaker arrangements do.

You're right - the image is not sharp as "**** in snow", but more "natural" - I'd say it pretty much reflects the image at an acoustic jazz-concert with no electric amplification.

Regards, Jesper
 
Hi Tyimo
Well, what I wanted from this speaker - and what I got - is a speaker free of room resonanses, due to the omnnidirectional setup.

The midwoofer acts really funny - the bass is firing down the enclosure, while the midband is radiating both horisontally and vertically into the room. It's a true lucky punch :D - it feels like the speaker haven't got an enclosure (no resonances)

The midwoofer as well as the tweeter is connected in phase. I tried to reverse the phase on the tweeter, but preferred the in-phase-connection.

I also tried mounting the tweeter face down, but that was no succes, not even with a cone underneath for spreading purposes.
 
c2cthomas said:
Similar to this: http://www.diyaudio.com/forums/attachment.php?s=&postid=1188296&stamp=1176356499
Perhaps a little of Mamboni Magic or BudP EnABL Voodoo!!! :yes: I have found that my Walsh 5 remakes are very nice speakers in respects to being an "omni" directional type of speaker. I find them great for my HT and general listening. :cheers:

Great Ideas going on here. It is something I have been thinking about building.
This pic (link) reminds me of the Robot in "Lost in Space".
No offense intended.
Ron
 
Juspur, love your design and seems well finished. Ahh the pencil case, what a touch!! Looks nice and simple. Quick question, the foam in the middle of your cabinet how is it attached? Oh and one more, how is the soundstage with down firing woofer? This is the first time I've seen design like this, yes I am a novice, with down firing woofer, the advantages? Thanks
 
Hi Nebojsa
The soundstage is very natural - I tried somehow to explain it in post #11 - but it's simply natural, if you think of acoustic presentations (jazz bands, symphoni orchesters etc.).

The foam is simply glued with contact-glue on the three contact-sides, and mounted in the enclosure.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.