Mark 1 3 way speakers

[Chluz]

I've been following a few threads on this forum, enough to know that you guys know what you're talking about! As I decided to build my own set of speakers, I though I would open a thread here so that you could give you're input and constructive criticism about this project.

This is my second speaker project, the first being a subwoofer which was a massive failure. All the details of this project can be found at this adress :
Mark 1 : 3 Way Speakers

To give you a quick rundown, the idea was to replace blown out speakers from a sony cabinet by changing the filters and the front faceplate. Therefore, the enclosure total size was pretty much pre-determined.

The drivers I used were :
- Tweeter : Hivi SD1.1A
- Mid : Visaton AL130m
- Low : Hivi F8

The Filters were completely built from scratch. The Project is still ongoing but is nearing completion. Any input is greatly appreciated, as I don't really have any experience in building these things; I'm finding it loads of fun though

Thanks !

[Cal Weldon]

Hi Chluz,

I haven't looked very deeply but a couple things stand out. First, the picture loading is very slow. I had to go get a coffee while I waited. I hope that's something at this end or it might discourage others from getting into it.

Once the pics fully loaded I see the tweeter and midrange side by side. This means it will be better if the speakers are on their sides rather than upright.

Also, you might wish to reconsider the layout of the XO before you make it. In the pic you show, the coils are close enough together to interact. There are some suggestions for layout on the net that include running coils 90 degrees to one another to prevent this.

You might also wish to add a ring of foam around the tweeter if you cannot rebate the baffle (faceplate)

Make sure your cabinet is well braced internally and properly damped.

I hope this didn't sound discouraging, I kinda like it when you can upgrade a set of boxes. Good luck with the project and show us more pics as you go along.

[Chluz]

Thanks for the input Cal !
I resized the images. I was accessing them from the same network as the server they were stored on... didn't realise that you guys had to go through my internet connection it should be better now !

I would have liked to place them aligned, but there wasn't enough space for that (a couple of cm missing), so I put them side by side. I had read somewhere that that would give phase problems, but I wasn't sure what that meant in listening terms... could you explain what the actual difference is between aligned and not aligned (sorry newbie here)

For the coils, I hadn't thought about that at all , thanks !! only problems is, I already soldered the parts... Would it be possible to avoid the interaction by placing metal plates between them ? or would that cause interaction between the coils and metal plates ?

Thanks again for having had a look at my project.

EDIT : Forgot to ask, whats the purpose of the foam ring for the tweeter, is it to stop the tweeter vibration from reaching the cabinet ?

[Cal Weldon]

Hi,

Having the mid and tweet side by side means that you might have comb filtering or lobing issues between them where they overlap. You will notice this if you move around while listening. It's sort of a drop out at certain frequencies. It all depends on what the XO frequency is. The higher the better for avoiding this.

I don't know what putting metal between the coils would do to avoid coil interaction.

The foam around the tweeter helps to "smooth" the sound. It reduces the diffraction caused by the flange of the tweeter if it's not rebated flush with the baffle. You can make it about the thickness of the flange or slightly thicker and do some experiments to see how much of a difference you notice. Make it about 8" around and cut the hole tight to the tweeter. Change it around a bit to see what works best or if you notice any difference at all.

There are others here that are much smarter than me but hopefully those things will help.

[Chluz]

Concerning the coils on the filter being too close together, I found this page : Placement of coils in crossover networks:.

Basically, putting aluminium next to the coil is going to make it worse. So I'm now thinking that i'm either going to have to live with it, or find a material that stops magnetic interactions, but doesn't react with the coils. I'm thinking some kind of very dense material (maybe schist in plates, the kind that was used on roofs before ?) but if it gets too crazy, I'm just gonna live with those 5-10% coil variations, and the eventual crosstalk...

[Moondog55]

I would ask you to seriously consider rebuilding the XO as Cal says.
turn the boxes on the side will help

[picowallspeaker]

I found another bug in the crossover : the L-pad on the woofer !!
That ,really sucks (energy) !!
You just can't put resistors before a woofer , only in some rare cases where
there is an impedance mismatch...damping factor...between the amplifier and the boxes

[Chluz]

Thanks for teh input.

You're right, i'm going to take out the two middle coils, and only move those out of the circuit board and onto a wooden support in front. That way the two remaining coils will be far enough from each other, and i'll have extra space to add better connectors for the cables !

I'll try and do that tonight and post some pics !!
Thanks again for your help.

[Chluz]

Originally Posted by picowallspeaker

I found another bug in the crossover : the L-pad on the woofer !!
That ,really sucks (energy) !!
You just can't put resistors before a woofer , only in some rare cases where
there is an impedance mismatch...damping factor...between the amplifier and the boxes

You're probably right. I looked dubious when I saw the L-pad that was needed to get balanced dB outputs from all speakers, and figured I can always add a couple of cables in and compare if I want to bypass the L-pad If it sounds better to my ear, the woofer Lpad will be only cosmetics . Maybe i'll look into a Baffle Step Correction circuit also, although I'm not familiar with them.

[picowallspeaker]

It's just a factor of spectral energy distribution ,and also human hearing (see Fletcher - Munson researches ). Nowhere you'll find resistors before the woofers ,even coils should have wire diameter > 1mm.