My First Bookshelf Project - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 11th February 2014, 09:19 AM   #1
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Default My First Bookshelf Project

Dear Experts,
I am new to speaker building. I have prepared a design based on Peerless India drivers. Woofer is 5.25" and tweeter is 26mm Silk Dome. I am attaching herewith a short ppt on the project. Please go through it and suggest improvements. If you need more information just reply to the post.

Regards
Prashant
Attached Files
File Type: pdf My two-way bookshelf project.pdf (298.2 KB, 306 views)
  Reply With Quote
Old 11th February 2014, 10:02 AM   #2
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Hi Prasi, I suspect in answer to your question will it sound boomy, the answer may well be yes. It looks like you have modeled with a series resistance (in line with the woofer) of 0.8 ohms. Is that based on the DCR of the coil you are planning on using? 0.8 ohms is quite a lot and will drop the efficiency (but make it model somewhat better, and with bigger volume).

See attached the step response for your modeled 20L with 52.7 hz tuning and 0.8 ohms series resistance. Then compare to step response for 7L with 66Hz tuning and 0.3 ohms series resistance. The wiggles in the step response shows how long the driver takes to return to rest, the more wiggles the more boomy I think it will sound. This is the tradeoff for getting lower extention.

I've also attached a plot comparing the 20L 52.7Hz FR curve to 7L 66Hz FR curve. You can see that the 7L the bass extension is much less, but I suspect that subjectively it will sound better. You can always build two boxes and try each and see what the difference is, no better way to learn!!

Note that I dropped the port diameter to 5cm for the 7L box model as it had terrible port resonance with 7cm port! The 7L size was the only other size I modeled as it was close to the recommended size.

ps. i thought that the quality of your hand drawing was excelent!

edit: and by the way, I'm no expert!!

Tony.
Attached Images
File Type: gif VB Step Response peerless india M13NH.gif (25.8 KB, 725 views)
File Type: gif VB Step Response peerless india M13NH_7L.gif (25.1 KB, 717 views)
File Type: gif m13nh_compare.gif (24.8 KB, 708 views)
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos

Last edited by wintermute; 11th February 2014 at 10:07 AM. Reason: no expert.
  Reply With Quote
Old 11th February 2014, 10:15 AM   #3
diyAudio Member
 
picowallspeaker's Avatar
 
Join Date: Apr 2007
Improvements ? I dunno! Try and see.
I would put the port on the back, and maybe a total rework in the dimensions.
The woofer could be on the top side ( obviously the cabinet is 90 !) and well, oh, the tweeter ! I prefer to keep every component separated.
In your design, the tweeter could stay below the woofer.
  Reply With Quote
Old 11th February 2014, 10:19 AM   #4
diyAudio Member
 
picowallspeaker's Avatar
 
Join Date: Apr 2007
Quote:
Originally Posted by wintermute View Post
edit: and by the way, I'm no expert!!

Tony.
Tony here, too, and same condition

You could use a lower sensitivity tweeter. Usually for hifi the final tuning brings some attenuation in the treble, so a direct approach ( less sensitive tw ) is better.
  Reply With Quote
Old 11th February 2014, 10:55 AM   #5
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Another option might be to go to the slightly bigger S16NI It is almost the same price as the M13H at this vendor Peerless - 6" Coated Paper Cone Woofer - S16NI and will outperform (in the low frequency stakes) the M13 hands down.

I modeled it in 20L (which is much smaller than the unibox recommendation of 66L) but that actually gives a very nice rolloff and a slightly rising response (rising as frequency decreases) It would be worth considering. I suspect that the 5" driver is targeted as being a midrange driver.

Transient response on the 16SI is good in the small enclosure too, as is it's power handling. I increased the port to 6CM for it, but you could probably use 7cm... again I just went with your volume I did not try to optimize, but I think you will see the advantage in the comparison graph from a low end point of view.

I've not heard any of these drivers, and with no Frequency response graph it is a bit hard to tell how suited to your application they are.

Anyway just another thing to consider

edit: I had the 0.8 ohms series resistance in this model not 0.3ohms that will have affected the result somewhat. with 20L and 0.3 ohms 43Hz tuning seems about the best.
Tony.
Attached Images
File Type: gif VB Step Response peerless india S16NI.gif (25.4 KB, 680 views)
File Type: gif S16I compare.gif (25.5 KB, 670 views)
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos

Last edited by wintermute; 11th February 2014 at 11:15 AM. Reason: make note that I forgot to remove the 0.8 ohms for this model
  Reply With Quote
Old 11th February 2014, 12:59 PM   #6
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Quote:
Originally Posted by wintermute View Post
Hi Prasi, I suspect in answer to your question will it sound boomy, the answer may well be yes. It looks like you have modeled with a series resistance (in line with the woofer) of 0.8 ohms. Is that based on the DCR of the coil you are planning on using? 0.8 ohms is quite a lot and will drop the efficiency (but make it model somewhat better, and with bigger volume).

See attached the step response for your modeled 20L with 52.7 hz tuning and 0.8 ohms series resistance. Then compare to step response for 7L with 66Hz tuning and 0.3 ohms series resistance. The wiggles in the step response shows how long the driver takes to return to rest, the more wiggles the more boomy I think it will sound. This is the tradeoff for getting lower extention.

I've also attached a plot comparing the 20L 52.7Hz FR curve to 7L 66Hz FR curve. You can see that the 7L the bass extension is much less, but I suspect that subjectively it will sound better. You can always build two boxes and try each and see what the difference is, no better way to learn!!

Note that I dropped the port diameter to 5cm for the 7L box model as it had terrible port resonance with 7cm port! The 7L size was the only other size I modeled as it was close to the recommended size.

ps. i thought that the quality of your hand drawing was excelent!

edit: and by the way, I'm no expert!!

Tony.
Dear wintermute,
Thanks a lot for your inputs. I had never understood the significance of "wiggles" in unibox. Now that you told me, I think I have screwed my design. It would have been "boom reflex box" and not a "bass reflex box"... Phew! . Thanks a lot.
Now regarding the 0.8 DCR resistance in series, somewhere I had read that one needs to put 0.8 ohms under Rs (external components).
  Reply With Quote
Old 11th February 2014, 01:03 PM   #7
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Quote:
Originally Posted by picowallspeaker View Post
Improvements ? I dunno! Try and see.
I would put the port on the back, and maybe a total rework in the dimensions.
The woofer could be on the top side ( obviously the cabinet is 90 !) and well, oh, the tweeter ! I prefer to keep every component separated.
In your design, the tweeter could stay below the woofer.
Thanks picowallspeaker,
I will put the tweeter below the woofer. What is the reason for recommendation for putting the port at the back?. also what changes in the dimensions do you suggest. to avoid standing waves? Or simply should i go by the "golden ratio"?
  Reply With Quote
Old 11th February 2014, 01:08 PM   #8
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Quote:
Originally Posted by picowallspeaker View Post
Tony here, too, and same condition

You could use a lower sensitivity tweeter. Usually for hifi the final tuning brings some attenuation in the treble, so a direct approach ( less sensitive tw ) is better.
Limited tweeter options available in India (Peerless Audio) and I heard that they manufacture good drivers and GR- Research (Speaker kits, loudspeaker design services, sub-woofers and amplifiers.) uses peerless India tweeters and woofers.
Also all tweeters have nearly the same sensitivity.
  Reply With Quote
Old 11th February 2014, 01:50 PM   #9
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Quote:
Originally Posted by wintermute View Post
Another option might be to go to the slightly bigger S16NI It is almost the same price as the M13H at this vendor Peerless - 6" Coated Paper Cone Woofer - S16NI and will outperform (in the low frequency stakes) the M13 hands down.

I modeled it in 20L (which is much smaller than the unibox recommendation of 66L) but that actually gives a very nice rolloff and a slightly rising response (rising as frequency decreases) It would be worth considering. I suspect that the 5" driver is targeted as being a midrange driver.

Transient response on the 16SI is good in the small enclosure too, as is it's power handling. I increased the port to 6CM for it, but you could probably use 7cm... again I just went with your volume I did not try to optimize, but I think you will see the advantage in the comparison graph from a low end point of view.

I've not heard any of these drivers, and with no Frequency response graph it is a bit hard to tell how suited to your application they are.

Anyway just another thing to consider

edit: I had the 0.8 ohms series resistance in this model not 0.3ohms that will have affected the result somewhat. with 20L and 0.3 ohms 43Hz tuning seems about the best.
Tony.
thank you wintermute, I see the advantage in using S20NI. Response curve is much better. As I said earlier, I am novice and I always thought that one can design a box only around unibox suggestions(60 liters is way too big for my living room).
With the 5.25 " driver, I thought to improve the low frequency extension, which is not correct as you have shown me in your post.
I will work on the simulations with S16NI and also another very good woofer (as per indian DIYers) the M16GJ (Peerless - 6.5" Glass Fiber Cone Woofer - M16GJ).

I will get back to you for your suggestions once again after preparing the entire design (Simulation, Drawing, Crossover). You have been very helpful to me and probably saved me INR 15000 (about AUD270).
I have designed the cross over based on the following link. Introduction to designing crossovers without measurement

Will the crossover network be of acceptable performance when built by above tutorial? Again I say that its my first project ...some imperfections are bound to be present. I am not looking to build Hi-Fi "audiophile" quality bookshelf speakers. But better than common "mass produced" Home Theaters.

P.S.
1. I will paste frequency response curves (if measured by some diy'ers)
2. what is your suggestion on the box dimensions. will they create problems (standingwaves)?
  Reply With Quote
Old 11th February 2014, 05:44 PM   #10
prasi is offline prasi  India
diyAudio Member
 
Join Date: Jan 2014
Default new design

Dear all,
here is my new design as per the suggestions received from experts. its based on peerless india drivers M16GJ 6.5" woofer and TL26SG tweeter. I hope this time I have done it right. Pl go through the attched pdf for details. I have box simulations in unibox, box drawing and crossover design based on rated impedances of drivers.
phew! keeping my fingers crossed so that experts will approve the design....
Attached Files
File Type: pdf My two-way bookshelf project - M16GJ-TL26SG.pdf (781.8 KB, 64 views)
  Reply With Quote

Reply


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
Choice of a bookshelf project greypey Full Range 26 21st December 2013 12:37 PM
bookshelf speaker project advice milen007 Multi-Way 42 8th November 2008 04:13 AM
small bookshelf project suggestions please gychang Full Range 4 10th November 2006 05:32 PM
Beginner bookshelf project? excetara2 Multi-Way 2 9th July 2006 04:00 PM
beginers project - 2 way bookshelf stickboy Multi-Way 7 18th November 2002 04:15 AM


New To Site? Need Help?

All times are GMT. The time now is 08:35 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2