Go Back   Home > Forums > >

Multi-Way Conventional loudspeakers with crossovers

Modding c-notes
Modding c-notes
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
Old 5th February 2021, 09:07 AM   #1
greenskin is offline greenskin
diyAudio Member
 
Join Date: Nov 2020
Default Modding c-notes

Hi, I have a plan to buy the C-notes component set, but make a different enclosure, while keeping internal volume, port cross section and volume, and the cross-over circuit unchanged.

What I want to do:
- replace rear port by a front-facing slot port
- remove the overlap between the mid-range driver and the tweeter (so, basically, move the midrange driver 1cm or so lower)
- make the cabinet slightly narrower
- use 18mm (more or less 3/4 inch) MDF and and add an internal cross brace
- play with height and depth to achieve the same internal volume, and the same cross-section and volume of the port as the original.

I have to admit, I do not have any objective reasons to do this, except cosmetic preferences. So, what I am asking is this: is it likely that I'll badly screw up acoustic characteristics with this change? (I assume it will sound slightly different, I hope it won't be bloodbath)
  Reply With Quote
Old 5th February 2021, 09:56 AM   #2
celef is offline celef
diyAudio Member
 
Join Date: Nov 2012
i do not know anything about c-notes, but in general, the results will depend on how meticulous the original design is you want to alter, if it is a sloppy design the outcome will be minor. like moving a port can have profound effect depending on how the internal layout is done, likewise moving drivers around and changing box materials and so on
  Reply With Quote
Old 5th February 2021, 04:16 PM   #3
TBTL is offline TBTL  Germany
diyAudio Member
 
Join Date: Oct 2013
A port might leak midrange sound which becomes more audible if it is located at the front.
Removing midrange-tweeter overlap slightly increases their centre-centre spacing and therefore slightly degrades vertical dispersion.
Making the cabinet narrower can make the baffle step correction incorrect. Difficult to say as celef notes above. I think that this has the largest influence on the sound.


These changes will not screw up the sound.


What can screw up the sound is placing the speakers against a wall, if that is the reason you want to move the port to the front.
  Reply With Quote
Old 5th February 2021, 04:29 PM   #4
xrk971 is online now xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC (Virginia)
Modding c-notes
Changing driver center to center distance and baffle width will change the crossover. You can change most other things but not the physical layout of CTC and baffle width/round over.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 5th February 2021, 04:53 PM   #5
greenskin is offline greenskin
diyAudio Member
 
Join Date: Nov 2020
Thank you both.

The speakers will probably be 30-40 cm from the wall, so, not ideal, but not the worst case either, I think.

The main reason for the change, really, is that the raw underbite in the driver positioning bugs me aesthetically, for some reason.

I take the point about the degradation in the vertical dispersion. Can I assume it will be be less severe the farther the listening position is from the speaker? Also, I am not building them as near field monitors aiming at a precise spot, but as general purpose speakers, to listen to some music while moving around the room.

Thanks again. The purpose of the project is to have a go at speaker cabinet making and finishing, without buying the premade kit. You reassure me that it probably will not be a pile of mess.
  Reply With Quote
Old 5th February 2021, 04:59 PM   #6
greenskin is offline greenskin
diyAudio Member
 
Join Date: Nov 2020
xrk971 - thanks for the input.
Food for thought. How does the worst case sound like, speculatively?
  Reply With Quote
Old 5th February 2021, 05:29 PM   #7
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Modding c-notes
Quote:
Originally Posted by xrk971 View Post
Changing driver center to center distance and baffle width will change the crossover.
That was my 1st thot as well. At the crossover frequency 1 is a huge distance. There is very solid reasoning for getting a tweeter as close as possible to the mid or midbass.

You are trying to reach a quarter-wavelength at the XO, almost impossible with a typical tweeter, and getting as close as possible helps solve issues with an XO where C-C is larger than optimal.

dave
__________________
Stay safe. Stay home. Respect the 2m bubble.
  Reply With Quote
Old 6th February 2021, 01:46 PM   #8
greenskin is offline greenskin
diyAudio Member
 
Join Date: Nov 2020
Thanks for the input, guys.

I guess, I will have to get ready to fine tune the cross over circuit after the build.
One more thing to try / learn ;-)
  Reply With Quote
Old 6th February 2021, 02:48 PM   #9
jReave is offline jReave  Canada
diyAudio Member
 
Join Date: Oct 2012
An alternative would be to router out the waveguide portion of the tweeter so the woofer fits flush with it. Just make sure you don't take out so much that you break the tweeter's seal with the baffle.

See this CC by Troels for an example. If you do it, I would suggest taping over the dome of the tweeter so it will remain free of any dust and debris as you make the cut.

Moving the woofer back to flush fit it with the baffle will also have a small effect on the sound but for this speaker and your listening habits, I wouldn't worry about it.

Also in general, if you change the baffle width by less than 10% the effects are usually acceptable. Adding more height to the speaker is also generally ok if you add it in at the bottom, or in other words you keep the drivers the same distances from the top of the front baffle as the original.
  Reply With Quote
Old 6th February 2021, 03:10 PM   #10
greenskin is offline greenskin
diyAudio Member
 
Join Date: Nov 2020
Quote:
Also in general, if you change the baffle width by less than 10% the effects are usually acceptable. Adding more height to the speaker is also generally ok if you add it in at the bottom, or in other words you keep the drivers the same distances from the top of the front baffle as the original.
I think, actually, this fits my case pretty well - the overall baffle width in the standard c-note is 190,5mm (7,5 inches). The full diameter of the driver is 134,9mm (5,3 inches). I planned to remove 16 to 18mm (8-9mm each side), so it would fall under 10%.

The routing out the overbite is a nice approach, looks very clean and integrated. I'll think about it. Thanks
  Reply With Quote

Reply


Modding c-notesHide this!Advertise here!
Thread Tools

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
Feedback Control Systems MIT lecture notes mikek Solid State 12 9th July 2016 06:07 PM
Comprehensive Op Amp App Notes @ APEX speaker Chip Amps 0 17th December 2005 02:45 PM
THATCORP application notes jackinnj Solid State 0 19th June 2005 04:20 PM
My Notes on DIY Audio available Jennice Everything Else 32 9th November 2003 06:35 PM
Notes on super regulators jwb Digital Source 0 26th July 2003 06:38 PM


New To Site? Need Help?

All times are GMT. The time now is 03:09 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki