Who wants to Design...
 
Notifications
Clear all

Who wants to Design a Speaker with Me?  

Page 1 / 6
  RSS

123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 12:09 am  

Anyone interested in helping out design a desktop speaker?  I am doing a new video on how to design a speaker from start to finish.  This will be the thread for it.  Feel free to ask any questions.  I'll also add the files, so you guys can try out different crossovers.  Ask questions about what is being done and why.  Who is in on this fun?

The drivers to be used are the PC83-4 and the ND16FA-4.  

I am thinking small sealed to be used with the mini earthquake. Thoughts from anyone?


Quote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 10:49 am  

Nice looking graphs, though the SPL levels are a bit disparate. Can always tune down the tweeter in the crossover.

Would you be able to redo and repost the  measurement graphs on the Mini Earthquake? I've looked at them with 3 different browsers and none will pop out like a normal picture does and I just cannot see/read them in the post. I'd like to see where that lands before going forward. That'll give a sense of what to do with the upper set of drivers.

-Charlie


ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 2:49 pm  

I should have the ZMA and FRD files later today.  We can see how much attenuation we'll need to put on the tweeter. My hope is to make this as simple of a crossover as possible for people. I'm not sure why they're not opening up fully for you. I'll have to add the mini earthquake stuff for you when I get back to the computer. 

 


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 3:12 pm  

@123toid

I don't know why either, I'm using my phone and 2 different desktops with both IE and Chrome. Other ones do, for example, the photo of the receiver you just put up does. 

Totally bizarre.

Totally.

🙂

-Charlie


ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 3:13 pm  

That is really weird. I'm getting ready to glue together the enclosures now. I'll try to re-upload those once the kids wake up from their nap. 


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 3:20 pm  

@123toid when you go to wake them up, use the link I just added above.

-Charlie


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 5:25 pm  

Using the T/S numbers provided for the PC83-4, I plugged them in and found:

Sealed - in box Q of 0.7 (considered optimum) gives an interior volume of 0.09 CuFt, and a FB of ~104 Hz

Ported - using the same box size above (0.09 CuFt), you can go a little lower with a FB of ~74 Hz and a F3 of ~71 Hz

Using the inside volume of 0.09 CuFt, and since the thinnest regular useable thickness of MDF available at the Home stores is 1/2", a couple of box sizes:

Golden Ratio - 9-3/4"H x 6-1/3"W x 4-1/3"D

Acoustic Ratio - 7-3/4"H x 6-1/3"W x 5/14"D

I thought that since the PC83-4 is only a hair more than 3-1/4" wide at the frame, the width could be made a bit more skinny, maybe 5-1/4"W, which would change the Golden Ratio to a depth of 5-1/4" also. Then glue another piece to the front, making the mount area for the PC83 1" thick while keeping the tweeter area 1/2", and you could then do a 1" round off on the edges there, while transitioning to a smaller one on the upper area. That'd help time align the drivers, while helping to mitigate baffle-step.

Crossover TBD.

Sound like a starting point?

 

-Charlie


ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 7:29 pm  

@tvor-ceasar

I think I want to go smaller size over a standard Q.  We can add some poly, but even making it considerably smaller really doesn't affect the response that much. I should have mentioned, I already had the box cut (sorry).  But your work is perfectly on point.  I kept it at 7" by 5" by 5"  Which is not the golden ratio, but I have used it for this driver and with the 6db high pass at 100hz that is built into the Lepai, it seems it should work out well.  Maybe I'll make a second box which has the tweeter behind the woofer for better acoustic alignment.  That is a cool idea. 


ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 7:32 pm  
W5 response

Here is the response of the W5.  This will be a 2.1 unit.  THe two desktop speakers and this as the sub. 


ReplyQuote
Scotty
(@scotty)
Active Member Registered
Joined: 4 months ago
Posts: 11
14/04/2020 7:53 pm  

@tvor-ceasar

What is the difference between the golden ratio and the acoustic ratio?
Do they have different internal volumes?

Scotty

 


ReplyQuote
Derek
(@derek)
Active Member Registered
Joined: 10 months ago
Posts: 6
14/04/2020 8:02 pm  

These would be pretty similar to the Reveals. I still have the parts for them, just never cut the boxes. 😱 I don't have a shop so kits are a big help to me. That was Olympic level procrastination though. 

The Reveals were not the only ones though. I was taking inventory of the drivers in my collection and making sure that the correct crossover parts had been obtained. Sadly at the time of purchase I didn't know that inductor DCR was even a thing or that it mattered. Luckily just a few cheaper ones were wrong.

Also, sorry for derailing the thread. Carry on.


123Toid liked
ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 8:08 pm  

7x5x5, is that internal or external measurements? If external, what is the board thickness? Looking for internal volume.

Thanks, I can see the graph now. Still no clue as to why it did that on my end.

 

Hmm, add a separate enclosure on top, backset, that would allow round over of the 3 edges not on the desk and would make for a visually interesting aesthetic. Kinda diggin' it.

 

Did you play that link for the kids? What interestingly fun times they were!

 

Addendum:

Looking at the tweeter dimensions, a 3" x 3" box, 4.5" (0.5" shorter than the main box depth) or what it needs to be set back to align. Nice rounded edges, maybe all 1/2", would give it an almost Art Deco style.

-Charlie


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 10:00 pm  

Aw shoot, you guys replied while I was writing. Sorry I missed you.

@Scotty,

Golden Ratio is something you'll find throughout time immemorial, from nature to art to man made objects. If you look back at most older speakers (mid to late 70's and earlier), they all have the same basic shape. The ratio is 1.6 units high x 1 unit wide x 0.6 units deep. The numbers actually go on forever, but 1 place is sufficient. It is reputed to be a very aesthetically pleasing ratio.

Acoustic Ratio is designed to minimize interior standing waves, and like above, the numbers are basically 1.2 units high x 1 unit wide x 0.8 units deep. Also like above, these numbers go on and on, but 1 place is close enough. 

Both ratios contain the same interior volume.

Thing is, these are just starting points. From the initial box to final product may be many iterations and many moves away from initial calculations. This is both the fun and frustration of the hobby. 

@Derek,

Sounds like a shot at getting going on the Reveals. I saw a guy who used hand tools in his kitchen to build some really nice cabinets (speaker boxes). And his kitchen was tiny. Lucky if it was 10' x 10' with counters and table.

 

PS: here's a link that gives some insight into the Golden Ratio.

-Charlie


Scotty and 123Toid liked
ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 2 years ago
Posts: 864
14/04/2020 10:03 pm  

@derek

It actually is the same enclosure as the reveals. Since I knew that the enclosure worked really well already with the PC83, I wanted to use it again. I'm thinking that this tweeter will actually be a better fit for the PC 83. That is why I decided to try it on this end. But I don't know yet. I'm going to try to get some measurements tonight. But yes, that is some serious procrastination, lol. 🤣 

@tvor-ceasar

Those are external measurements with half inch material. The woofer is going to be round over and set behind. So the acoustic centers will be fairly off. But I'll just equate for that in the crossover. I'm going to try to get some measurements for everyone to play with tonight. Then I'll go ahead and hook all of them up and do some sound tests and measurements. And then we can decide together what we think looks like the best combination. Then I'll do a video and give you guys all credit. 

PS, the kids enjoyed the song.


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Reputable Member Registered
Joined: 1 year ago
Posts: 364
14/04/2020 10:54 pm  
Posted by: @123toid

@derek

It actually is the same enclosure as the reveals. Since I knew that the enclosure worked really well already with the PC83, I wanted to use it again. I'm thinking that this tweeter will actually be a better fit for the PC 83. That is why I decided to try it on this end. But I don't know yet. I'm going to try to get some measurements tonight. But yes, that is some serious procrastination, lol. 🤣 

@tvor-ceasar

Those are external measurements with half inch material. The woofer is going to be round over and set behind. So the acoustic centers will be fairly off. But I'll just equate for that in the crossover. I'm going to try to get some measurements for everyone to play with tonight. Then I'll go ahead and hook all of them up and do some sound tests and measurements. And then we can decide together what we think looks like the best combination. Then I'll do a video and give you guys all credit. 

PS, the kids enjoyed the song.

Check my addendum above. I was typing while you were. You could even slim it down to 2.5" wide if need be. You could trim where the tweeter box hits the main box with some small cove, if you can find it or maybe some 45° trim. 

I ran the numbers for outside dims and 1/2" board, comes out to be an in box Q of 0.79 and a FB of ~117 Hz. Still a nice bottom for such a small driver.

Glad the kids liked the song. It's never to early to introduce the kids to Zappa. 😀

 

-Charlie


123Toid liked
ReplyQuote
Page 1 / 6
Share:
%d bloggers like this: