Trying to understand speaker position... - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 4th March 2011, 08:34 PM   #1
diyAudio Member
Join Date: Jun 2010
Location: Memphis
Default Trying to understand speaker position...

Hi folks, I am a certified lurker until today.

Background: I am about to undertake a speaker building project using the Greg Monfort (thanks Greg) Alpair 10 cabinet design. It seems straightforward enough and the design appeals to me. The driver I have chosen for this the MarkAudion Alpair 10 generation 2. The cabinets will be constructed of 3/4" baltic birch ply with a zebrawood veneer. I also intend to put a flared base to give the speakers a wider stance for stability reasons.

Question: As you can see by the attached drawing provided by Greg Monfort the driver is placed about 2/3 up from the bottom of the cabinet. I would like to have the driver placed just 1.5 inches from the top of the cabinet if, everything else being equal, it doesn't affect the sound/performance of the speaker.

This change is just for personal taste and if it makes a difference I will be driving these with the Elekit TU879 S, an 8.5 watt @ 8ohms tube amp.

Your thoughts kind members would be most appreciated.
Also I did look for related information here at diyaudio but have come up empty handed.
Attached Images
File Type: png Screen shot 2011-03-04 at 3.22.25 PM.png (113.4 KB, 196 views)
  Reply With Quote
Old 5th March 2011, 01:13 PM   #2
diyAudio Member
Join Date: Jun 2010
Location: Memphis
Have I done something inappropriate ?
  Reply With Quote
Old 5th March 2011, 01:17 PM   #3
Pano is offline Pano  United States
diyAudio Moderator
Pano's Avatar
Join Date: Oct 2004
Location: SW Florida
Blog Entries: 4
Give it time. The forum is slowest on the weekends.
Take the Speaker Voltage Test!
planet10 needs your help: Let's help Ruth and Dave
  Reply With Quote
Old 5th March 2011, 01:20 PM   #4
diyAudio Member
Join Date: Feb 2010
Location: in half space
Seeing as what you've got there is a transmission line, moving the speaker will impact the sound.

This is a good overview, and includes in-depth references:

  Reply With Quote
Old 5th March 2011, 01:29 PM   #5
diyAudio Member
Join Date: Jun 2010
Location: Memphis
Keriwena, Thanks for some information. I am not sure I understand how to make adjustments though.
  Reply With Quote
Old 5th March 2011, 04:35 PM   #6
zman01 is offline zman01  Bangladesh
diyAudio Member
Join Date: Feb 2011
Location: Dhaka
Nauralmystic, I am no expert, but I think it will have an impact - trust that Greg Monfort made that exact placement of driver becasue it was optimal for his design.

If you prefer the driver a bit higher from the floor, using spikes you will gain 0.5" on height.

Also are you sure that Alpair 10.2 will work well in this cabinet? AFAIK Alpair 10.2 is new (2nd Gen) and improved version of Alpair 10. The plans are for Alpair 10, and using Alpair 10.2 might need slightly different considerations. If you already have and answer to that, great. If not you can post the question at the Markaudio section of the forums.
  Reply With Quote
Old 5th March 2011, 04:51 PM   #7
diyAudio Member
Join Date: Jun 2010
Location: Memphis
zman01, You make an excellent point. I had not considered that there are differences between the 10 and 10.2. I have posted a more general question about which driver to select in the MarkAudio section. Once I get some response to it I will address the cabinet design more specifically.

THanks to all who have taken their time to respond.
  Reply With Quote
Old 5th March 2011, 04:58 PM   #8
AEIOU is offline AEIOU  United States
Account disabled at member's request
AEIOU's Avatar
Join Date: Jun 2009
Send a message via AIM to AEIOU Send a message via MSN to AEIOU Send a message via Yahoo to AEIOU
I bet that you can move the driver higher without completely impacting the design. Typically you just need to adjust the amount of stuffing.
Someone took a TABAQ and moved the driver higher and it worked just fine.
What you need though, is to model you design. Someone who has Martin Kings software could model it for you.
  Reply With Quote
Old 5th March 2011, 05:43 PM   #9
diyAudio Moderator
planet10's Avatar
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
The driver offset is important to the design. It kills the 1st objectionable harmonic, allowing for less damping and a net gain in bass reinforcement. The offset is not ~2/3 but likely carefully placed to within fractions of an inch.

If you end load the driver you will need more damping and will end up with less bass or more ripple.

ML-TLs are typically fairly tolerent, A10.2 will probably work just fine (althou starting from scratch you would probably end up with something slightly different)

community sites,, ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 6th March 2011, 03:53 PM   #10
Squeak is offline Squeak  Denmark
diyAudio Member
Squeak's Avatar
Join Date: Jul 2007
Location: Frederiksberg
Consider doing a ML-TQWT if you want the driver at sitting down ear hight (1 to 1.10 metres, is a good compromise). A slanted wall within the cap will give you the driver displacement effect.
  Reply With Quote


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
25-position switched attenuator using a pair of 5-position switches? ray_moth Tubes / Valves 1 4th May 2008 08:02 AM
Please help me understand speaker fundamentals jnb Multi-Way 5 20th July 2007 03:26 AM
Driver Position hlj Full Range 2 1st June 2006 06:26 PM
Speaker design challenge: 105db 20 - 20k at listening position paulspencer Multi-Way 28 9th July 2005 10:12 AM
Port position? MisterB Multi-Way 3 20th February 2002 03:42 PM

New To Site? Need Help?

All times are GMT. The time now is 09:22 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2