Author Topic: My next speaker build (again...)  (Read 7137 times)

Offline JimGore

My next speaker build (again...)
« on: October 24, 2017, 09:54:00 AM »
Some of you may know that I like to build something a little different each time - what's the point of doing the same 2 way over and over again using different drivers? 

Square box, little bigger, little smaller, drivers this configuration or that, port tuning higher or lower - it's boring.  Once you have built a set or two like that you know everything you can about it.

The only way to learn new things and expand your horizon a bit is to try different things, so I have been thinking what I can build myself next.

I have been completely jaded by the high efficiency designs, and it manifests itself mainly in 2 ways:

1.  Just about every other speaker sounds slow and lazy to me.  It's as if they just don't have the transient response capabilities.
2.  The average loudspeaker just can't seem to satisfy my need for listening at reference levels - many can manage the SPL, but it starts to sound like they are straining therefore the enjoyment isn't quite there.

As you all know there are difficulties with HE as well - one of them being that getting any significant level of deep bass extension out of them is a problem.  They either need massive cabinets or EQ in some form or another.  Now I don't normally mind giving up that bass extension in order to have the other benefits, so not a problem for me but it is still a problem.

Next thing is that somehow very narrow speakers can often be made to image in a way that wider baffle speaker cannot quite achieve.  I can't really say why (I am sure there is an answer - I have never bothered to figure it out), but it's an interesting effect anyway and one I could probably make use of.

So after all that rambling, my idea is to build as narrow as possible, but go very deep dimensionally to achieve the internal volume I need.  Design goals:
* Small drivers so I can keep the cabinet narrow.
* Because I will use non HE (ie normal) drivers, it needs to be at least 3 way.
* Reasonable power handling - I don't want to hear "strain" at my listening levels.  The bass normally suffers first, so I will use 4x bass drivers in series-parallel connection for an 8 ohm impedance.
* Non parallel side walls to reduce internal standing waves at fixed frequencies.
* Must at least look like something interesting.  Like I said - I am bored with the square box plan.

After some drawings and iterations in CAD, this is what I reckon I will do:

















So I will use (10x) Scan speak discovery 15W/8434G-00 for bass and midrange duty (because I have them) and the tweeters will be Scan speak discovery D2608/913000

Cabinet will be Birch ply (probably 21mm or whatever I have here).  The sides will be painted super high gloss automotive white (maybe with a bit of a pearl in it), and the inside section (shown as dark wood now) will be some kind of either wood veneer or otherwise something else if I can find an interesting hardwood.  It is 1200mm tall, the baffle is 160mm wide, and total depth or around 600mm.  Strange dimensions for sure.

The design will be bass reflex, with port on the bottom as I don't want the port to spoil the looks.

Lastly - this build is not supposed to be an "ultimate" build if that makes any sense.  Rather it's just me having some fun with things I have laying around, and also the opportunity to experiment with different cabinet shapes and designs.

What do you think?  Feel free to share your thoughts, good or bad  :2thumbs:

Kind regards,
Ian.

Offline gavinbirss

Re: My next speaker build (again...)
« Reply #1 on: October 24, 2017, 09:59:48 AM »
Ian,

What about making tweeter and midrange open chamber (open at the rear) and / or decoupling tweeter from the bass drivers?

Offline JimGore

Re: My next speaker build (again...)
« Reply #2 on: October 24, 2017, 10:15:40 AM »
Hi Gavin,

I have done all those things in other builds.  It's interesting and there are certainly benefits.  Remember that anything you do in speaker design is a trade-off. 

There are never any clear outright wins, so the question becomes what the actual benefit is vs what the price is you pay for doing it.

Kind regards,
Ian.

Offline d0dja

Re: My next speaker build (again...)
« Reply #3 on: October 24, 2017, 10:29:21 AM »
Interesting... you're not worried about standing waves between the extensions of the side panels poking at at the front? To keep the simplicity of fabrication, maybe carve out circular cutouts either side of the drivers running from the front backwards (parallel to driver axis) on either side?

Maybe something worth considering, create a diffusion surface inside to reduce standing waves within the enclosure, so that you won't need too much damping?

And stand it on some stainless steel tubing on a plinth to lift it off the ground (cantilever?) and give it "air" in the design.

Offline JimGore

Re: My next speaker build (again...)
« Reply #4 on: October 24, 2017, 10:42:09 AM »
Hi R,

Yip, there will be a price to be paid for the sides poking past, but I don't know just how "expensive" that will be.  It's not poking past much so hopefully not too much of an issue, though only the microphone will be able to tell me the truth about it...

The plinth has been a bit of a concern to me - the speaker definitely needs something because it will topple very easily as is.  The question is how to do something that fits nicely into the design and doesn't spoil the simplicity?  Do you have any more info on what you propose, or perhaps a link to something similar?

Thanks!
Ian.

Offline Hi-Phibian

  • Commercial Member
  • Trade Count: (+44)
  • *****
  • Posts: 11,944
  • Total likes: 54
  • I really prefer email, see my banner for address..
    • Croak Audio Exploration
Re: My next speaker build (again...)
« Reply #5 on: October 24, 2017, 11:13:32 AM »
I like the concept very much.  I like the different. 

Pity they would be too deep for me. 



No plinth


Proprietor of Croak Audio Exploration.
Fair, not crazy, cash paid for turntables and tonearms from Rega, Linn and Thorens.          http://www.croak.co.za

Offline Samayanaya

Re: My next speaker build (again...)
« Reply #6 on: October 24, 2017, 12:00:45 PM »
To keep it from falling over, add feet to the rear on extensions like Hi-Phib suggested but only in the rear. Then raise the rear to accommodate the extra height from the feet but keep the rest of the shape as is.

Offline El Sid

Re: My next speaker build (again...)
« Reply #7 on: October 24, 2017, 12:37:08 PM »
I know it's early days and will depend on measurements once the cabs can be tested and many other things, but any preliminary sense of where you will be crossing over, and what order crossovers you're considering? To my inexpert eye it looks like the bass won't go down that far, but I'm sure you have some tricks up your sleeve.... ;)

The frequency responses and parameters are posted just out of interest



Offline JimGore

Re: My next speaker build (again...)
« Reply #8 on: October 24, 2017, 01:20:14 PM »
No plinth




To keep it from falling over, add feet to the rear on extensions like Hi-Phib suggested but only in the rear. Then raise the rear to accommodate the extra height from the feet but keep the rest of the shape as is.


Thanks for the suggestions, I like  :dop:


I know it's early days and will depend on measurements once the cabs can be tested and many other things, but any preliminary sense of where you will be crossing over, and what order crossovers you're considering? To my inexpert eye it looks like the bass won't go down that far, but I'm sure you have some tricks up your sleeve.... ;)

I must be honest - I am yet to measure a driver in a cab which looks much like those manufacturers graphs, so I don't pay too much attention to them  :sulky:

What I rather do is look at the specs in detail and choose based on them. Any funny business I come across in the measurements are resolved in the crossover as needed.

The crossover point: difficult to say right now. My normal process is to do the crossover design on the PC and tweak until I am happy, then I build them on the floor next to the speaker. It's a huge mess of wires, crocodile clips and parts all over the show. From there I do citical listening and try to identify what I like and dislike about it. After that I make some assumptions around what's causing the things I dislike (this comes from years and years of experience doing just that), then I start making tweaks to the crossover until such time as I am happy with it.

Sometimes a certain crossover simply cannot be tweaked until it sounds right, so then I go back to the PC and design another, and the whole process starts again.

Each driver and combination of drivers have what I can only call a set spot where they just sound right. The trick is to get to that point with them all, and unfortunately a microphone simply cannot provide that answer, so I trust my ears above all else I  the final voicing.

It's quite amazing to go through the process, because at a certain point, when everything falls into place it's as if the speaker is transformed - from the sum of the parts through to some thing which is more tHan the sum of the parts. All of a sudden it just works, and sings beautifully.  To me at least this is the difference between a good speaker and a great speaker, and it is unfortunately nearly imposible to teach or explain to someone else who hasn't put the time in and paid the school fees.

Sometimes I am lucky and I will get it done in half a day. Other times it can take me weeks and weeks. You just stick to it and keep working until it's done.

Obviously I can't speak for anyone else, and opinions and preferences differ, so what's great to me may not be great for everyone. I am by no means implying that my way is correct or the best, it's just what works for me.

It's one of the reasons I find this audio hobby so interesting  ;D

Kind regards,
Ian.

Offline u235

  • Trade Count: (+3)
  • AVForums Grandmaster
  • *****
  • Posts: 2,421
  • Total likes: 0
  • I'm sure I can hear the difference now.........
    • Youngblood Consultants
Re: My next speaker build (again...)
« Reply #9 on: October 24, 2017, 01:33:39 PM »
Not into horns Ian?

I'm listening to a pair (Coral design) and they give me all that wonderful high sensitivity with fantastic bass extension.
Upon the plains bleach the bones of countless millions, who on the dawn of victory paused to rest, and there resting died.

Offline d0dja

Re: My next speaker build (again...)
« Reply #10 on: October 24, 2017, 04:16:06 PM »
I like this kind of stand... although I was thinking more dik stainless steel tube than sheet metal...

Not too high, maybe 6-12 inches off the ground, to give a "floating" effect, and to lift the directional drivers to the right ear height. May reduce bass a little as you dont get floor gain. But hey, that's what EQ is for.





Offline Mars67

Re: My next speaker build (again...)
« Reply #11 on: October 25, 2017, 02:26:35 PM »
Already subscribed!!!

Offline tab.deboer

Re: My next speaker build (again...)
« Reply #12 on: October 25, 2017, 02:28:53 PM »

Offline Air

  • Commercial Member
  • Trade Count: (+1)
  • *****
  • Posts: 734
  • Total likes: 20
  • Music lover and involved in industry
    • Airmusic
Re: My next speaker build (again...)
« Reply #13 on: October 25, 2017, 02:48:13 PM »
 :thumbs: I like the concept, Ian.

With tweeter below the mid, I would look at drivers that allow for an easy 2nd order LR slopes. In my experience, good phase integration at crossover point is easily achieved with this approach if listening height is factored in.

Maybe you can angle the partition below the midrange to also ensure that the top and bottom walls of the mid enclosure are not parallel, a small incremental and perhaps theoretical benefit but every bit helps :thinking:

Offline kenvanraas

Re: My next speaker build (again...)
« Reply #14 on: October 25, 2017, 09:07:36 PM »
Hi Ian,
What about passive radiators mounted on the sides,ala KEF,Goldenear Triton One?
« Last Edit: October 25, 2017, 09:12:52 PM by kenvanraas »