Pensil P70 mathematics
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Planet 10 hifi Home of the Frugal-phile™ - Planet 10 HiFi

 27th February 2012, 09:27 AM #1 Waves73   diyAudio Member   Join Date: Oct 2011 Location: Runcorn, Cheshire Pensil P70 mathematics Hi, I'm just about to start building a pair of Pensil 7's, using a set of CHP70 1st generation drivers. Following the plans downloaded from Planet10's archive, I will be using 18mm birch plywood and a piece of 18mm solid walnut for the speaker baffle. And this is where the maths comes in to it. The walnut is only 144mm wide (the plans state a 146.1mm wide baffle). Although this is a small difference in size it does effect the overall volume of the speaker. By using the plans dimensions I've calculated the internal volume of the 7's to be 38.45litres. After recalculating for the change in width, this becomes 37.93litres. If I use the 144mm wide baffle and alter the internal depth, by adding 4mm, this brings the internal volume back to 38.45litres. The question is, can these alteration be used and not effect the sonic presentation of the speakers? Any advice welcome. Mark
 27th February 2012, 11:01 AM #2 zman01   diyAudio Member   Join Date: Feb 2011 Location: Dhaka Mark, what you have proposed should be ok, but you might as well wait for a more expert opinion from folks who have a solid understanding of TL theory. I have a pair of these drivers and like them a lot, specially the midrange.
 27th February 2012, 04:15 PM #3 chrisb diyAudio Member   Join Date: Aug 2002 Location: victoria BC As long as you're adjusting only the aspect ratio of w x d , but not length, driver location or ports, you should be fine. Try to rebate the driver cutout 6mm for a flush fit, and don't forget to profile the rear side of cut out before assembly. __________________ like my mind, this space intentionally blank
 27th February 2012, 06:24 PM #4 planet10   frugal-phile(tm) diyAudio Moderator     Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III What Chris says is accurate, i will only add that you will also need to increase the height of the port so that its area remains the same. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA
 27th February 2012, 08:50 PM #5 Waves73   diyAudio Member   Join Date: Oct 2011 Location: Runcorn, Cheshire Thanks guys for the advice. Once I've re-calculated the measurements, and bought the plywood, I'm going to get on with the build and post a few pictures. Next stop, timber merchants.
 6th March 2012, 04:53 AM #6 skeeter99   diyAudio Member     Join Date: Feb 2010 Location: Seattle, WA So how has the build gone? I love my Pensils and really enjoy seeing people fall in love with theirs as well. Scott
 7th March 2012, 07:43 PM #7 Waves73   diyAudio Member   Join Date: Oct 2011 Location: Runcorn, Cheshire Hi Scott. The build is slow going. Time and money are an unfortunate factor. I've got the drivers and wood for the baffles. Just got to get the plywood for the rest of the cabinets and find the time to build. I bought three CHP70's. Two for the Pensils and a third to design and build a centre speaker. The plans for the centre speaker are still in development but il draw them up and post them. Will be good to get some feedback on my design.
 7th March 2012, 07:59 PM #8 skeeter99   diyAudio Member     Join Date: Feb 2010 Location: Seattle, WA Cool. I understand how slow things can go, just check out my thread on my build! Took FOREVER to get done but I really enjoy them daily. For a center design, talk to Dave (Planet10). We did a custom Mar-Ken design for my 12's and it blends in with my SuperPensils pretty much perfectly and looks nice also. Scott
 8th March 2012, 12:28 AM #9 malibujeff   diyAudio Member     Join Date: Mar 2010 Location: Georgia Waves73, Get them finished! Your going to be surprised when you listen
Waves73
diyAudio Member

Join Date: Oct 2011
Location: Runcorn, Cheshire
Well I've eventually started the prep for the Pensil 7's build. Started running in the drivers. They are just in their boxes and wired up to an old stereo at the moment but are already sounding pretty good. Also designed and made a router jig and started work on the baffles.

I've also done some initial calculations for the centre speaker. Attached are the plans and dimensions. The design is for a sealed enclosure with an F-3 of 81hz.

A couple of questions about the design are:

As the baffle isn't very high (internal hight of only 109mm) will their be any problems having the driver so close to the wall?

Would I need to consider any form of BSC for the design?

Any feedback would be much appreciated.
Mark
Attached Images
 centre_version 1.jpg (115.9 KB, 183 views)

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post malibujeff Planet 10 hifi 19 10th January 2012 10:26 AM JorgeO Planet 10 hifi 9 28th June 2011 02:51 PM zman01 Planet 10 hifi 3 24th March 2011 04:48 AM Squeak Planet 10 hifi 0 11th March 2011 10:18 AM Christer Digital Source 13 16th June 2003 05:58 AM

 New To Site? Need Help?

All times are GMT. The time now is 02:49 PM.