Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

First Build: Pensil P11
First Build: Pensil P11
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st July 2020, 01:05 AM   #1
Serevro is offline Serevro  Mexico
diyAudio Member
 
Join Date: Jun 2020
Default First Build: Pensil P11

Hello Everyone,

Recently I stumbled on an ad for the Wrensilva's audio consoles, and the idea of making a similar piece stuck in my head. I'm quite competent making cabinets and have machinery and some materials available. On the other side, I'm an utter neophyte regarding audio; so I started lurking here.

Since I know next to nothing about electronics I opted to go with a full range design. I got a good deal on a pair of Pluvia 11s and so, I have the drivers in my hands. I later opted to make a pair of speakers instead of the audio console, since don't really have room for it.

I usually listen from Spotify via Bluetooth, have a number of classical music CD's which I listen from time to time too. I bought an Onkyo TX8220 to power the speakers, probably arriving later this week. Not a conossieur, as you may notice.

Initially I was thinking into making a folded horn design, but found a review of the Pensil 11 on HiFi Pig that changed my mind. Also it looks easier to build.

Now regarding the build, I'm going to list some hard constraints, some good things, and some questions in no particular order. Would appreciate your input.
  • First of all, I'm using the Pensil A11/P11 plan as base for this build: https://frugal-phile.com/boxlib/pens...silA11-P11.pdf
  • Something not good: I don't have a source for good plywood. On the other hand I have plenty of MDF. I made a preliminar design using 15 mm MDF keeping the internal dimensions untouched. Could use other thicknesses, but I'm used to work with 15 mm and have more finishing options with it.
  • Another not so good thing: I have no clamps. I will "press" the panels using Minifix fittings while the glue cures. I've done that before with furniture, let's see how it works on speakers.
  • Something positive: I have plenty of dampening materials: delcron, felt, PU foam, eggshell foam, etc. Also, have access to some well tooled CNC routers.
  • A question: If not using internal bracing, how do you keep the fiber stuffing from going to the bottom?
  • Regarding the terminal cup: Is there a prefered place to put it or it doesn't matter as much?
Thanks a lot.


Rodrigo
Attached Images
File Type: jpg Pensil 11 CAD Preliminar.jpg (66.0 KB, 202 views)
  Reply With Quote
Old 1st July 2020, 07:45 AM   #2
Scottmoose is offline Scottmoose  United Kingdom
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
A couple of points:

-You are asking for trouble if you use unbraced, single-thickness 15mm MDF in an LF enclosure of this size.

-Do not use egg-crate foam. I stress this point for every single pensil: I did not design them to use it, and it doesn't (can't) provide the correct damping characteristics. It has uses, but not for these speakers. The default is dacron (hollow-fibre stuffing).

-The stuffing is uniformly distributed throughout the box, keeping it a few inches away from the rear of the driver. Generally it's self-supporting at the densities in question, but you can put a dowel or two across just above the vent. However, if you're going to use MDF, above all insufficiently thick MDF, bracing of some kind is essentially mandatory, with the longitudinal bracing of the type shown in the [Super]Pensil 12P pdf being the most effective.
__________________
www.wodendesign.com (commercial site)
www.frugal-horn.com www.frugal-phile.com (community sites)

Last edited by Scottmoose; 1st July 2020 at 07:48 AM.
  Reply With Quote
Old 1st July 2020, 06:24 PM   #3
chrisb is offline chrisb  Canada
diyAudio Member
 
Join Date: Aug 2002
Location: victoria BC
Having built a few pairs of Pensils and many of Scottís other designs, Iíll strongly second his remarks. In my past active building career, I had access to more than sufficient free off-cuts or wholesale priced MDF, but after a test build of identical enclosure and driver design in the two materials (3/4Ē MDF and 18mm Baltic birch) in the early 2000ís, I used MDF only for templates and base plinths.
Aside from the vent opening, itís critical that all joints are air tight - something thatís certainly not the case for furniture or kitchen cabinets. If you have access to CNC machining, Iíd suggest at least 18mm MDF, and the use of dadoes/rabbeted joints - glue lock joints if you can manage them, but note that MDF can be both become fragile when so machined, and thanks its heat tempered surface hold a sharp enough edge to cause physical injury.

Cue the Greek chorus of debate on the merits of different material types and construction/joinery techniques.

As to to the location of terminals, Iíd personally opine that it hardly matters diddly squat - just make sure that the back panel is both removable for installation / adjustment of damping fill, and well sealed with something like closed cell foam weather stripping tape.
__________________
Weíre just a bunch of monkeys on a big blue spinning ball - Don Caron
  Reply With Quote
Old 3rd July 2020, 05:47 PM   #4
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
First Build: Pensil P11
If MDF is all you have, 15mm is too thing for this box. You could get away with well braced 15mm quality plywood, but you will need to use at least 18mm MDF and it will likely need more bracing than the 15mm ply.

Click the image to open in full size.

From this drawing: the braces that are pararllel to the bffle should not extend to the point that they are behind the driver (you could probably make then in a bit taller.and i would not put any holes underneath were the braces cross. Make sure the braces are off-centre. With 18mm MDF you may need more bracing. Probably another side-to-side set. Account for the volume of th braces when doing the box size calculation.

dave
__________________
Stay safe. Stay home. Respect the 2m bubble.
  Reply With Quote
Old 5th July 2020, 03:53 PM   #5
Serevro is offline Serevro  Mexico
diyAudio Member
 
Join Date: Jun 2020
Thank you for your valuable feedback.

I made the pertinent changes: I'll go with 18 mm MDF for the sides, top and bottom, and 27 mm (15 + 12) in the front. Will use dadoes in most unions.

Next thing I will do is take into account the volume substracted by the braces and back mount.

I'm probably using 2 faces finished MDF for most parts, does the absence of porosity affects substantially the outcome?

Thank you again,


Rodrigo
Attached Images
File Type: jpg Pensil 11 CAD Preliminar 2.jpg (69.4 KB, 74 views)
 

Reply


First Build: Pensil P11Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Yet another Pensil 10p build AEE Full Range 23 18th March 2020 01:09 AM
My Pensil 6 build. MartinHyde Planet 10 hifi 43 10th January 2015 04:33 PM
My Super Pensil Build - Link To Build Post tlarwa Planet 10 hifi 0 21st December 2014 06:10 PM
Pensil 10.2 Build (Yet Another) cogitech Planet 10 hifi 44 14th March 2013 03:36 AM
My first build - Pensil P70 JorgeO Planet 10 hifi 9 28th June 2011 02:51 PM


New To Site? Need Help?

All times are GMT. The time now is 11:51 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki