More than happy with first build.

[hahbs]

So first of all thank you so much to those that helped me through this. Many of you chimed in at the right time to save me from pursuing a course of failure.

I'm not just satisfied with the results, I'm blown away. I've been running 2 channel all day with a big smile on my face. I also put on a couple of movies to see how my new rears (my old fronts) sound from the back. Maybe a bit overkill but it's pretty awesome. I'm definitely going to make a center to match my fronts. My Polk Audio center just doesn't keep up with the range of sound of the fronts.

This was my first build and it's based on Holtz's mini statements. I chose to go with a different tweeter, 4-ohm series instead of 8-ohm RS180's, and my own crossover. I also beefed up the cabinet a bit.

I started with 3/4" MDF and followed the design of the mini's. I fiberglassed the inside back wall and all the corners. I added 1/2" to the top, front, and one of the sides. A 1/4" was added to the other side. I did it figuring it would offset the drivers relative to the baffle. I also cut in a little more for the 1/4" side at the back to minimize common diffraction points. I'm not sure any of this actually has a positive effect but I'd like to think so
I padded the walls with the egg crate foamy stuff. I used fiberglass insulation for the mid range section. They weigh about a 100 lbs each. On the outside I used a chestnut poly stain to feed the MDF and prep it for paint. I let it sit for about 2 weeks then sanded it down and added 3 layers of aged copper. I'm going to run them like that for about a month and then add the final coats of whatever I decide on.

Screwed in are the RS180-4's, W4-1337SD, Aurum Cantus G2 Ribbon.





The crossover is pretty simple. I did the measurements in the room and designed the crossover based on them. I also plugged in my simulated drivers in to the same crossover to see if I would get similar results. It was pretty awesome to see how close they were. That Jeff guy is pretty great.



This is the results 33" from the mic with the speaker roughly in the middle of my 13x12 room. This measurement was done when I had the crossover components scattered across the floor and alligator clipped together. I also only had half the screws installed for each speaker. Just wanted to see if the crossover was going to work in reality. I'll post updated results when I get around to it.



In all I'm very happy with these. They sound so much more balanced then anything I've ever heard. Nothing stands out yet I hear sounds I never new existed in songs. I know this project is pretty amateur but you gotta start somewhere and I've got the bug now. I really enjoy reading all the posts on here. Some amazing stuff you guys do. Thanks again to all those that helped me out.

 

[xrk971]

Nice work on cabinets. You probably should have flush mounted the drivers rather than recessed with round over. That's adding diffraction as seen by ripples in measurement. I am surprised you need a 1R across the mid range terminals - that's a lot of attenuation - was that needed to level match mid to woofers? Is it the mic but data falls off at 13khz rather than go to 25kHz+ which is what I would expect with a ribbon.

 

[djn]

beautiful works. I am surprised that the tweet is rolling off at 11khz as their graph show them flat out to 14khz.

 

[hahbs]

You're right I probably should have flush mounted. I was originally going to but later decided to recess it after looking at some pictures of other projects. I also expected a 1/4" would be much more subtle. One of my regrets.

Yeah the 1R is needed. I pulled it off and gave it a listen and the mids smacked me in the face. It was the only way I could find to balance everything without making sacrifices elsewhere. The 1337 would either climb back in too much after 10k, or falloff and leave a nasty dip. I was able to resolve it by adding components but I wanted to keep this pretty simple.

The falloff for the tweeter is software side. I had it set to 15K with a fade out function. On my next test run I'll do a full sweep.

 

[wolf_teeth]

Danger Will Robinson!

As XRK mentioned, that 1 ohm resistor really cuts a lot of output, so it will run HOT(!), not to mention that your amplifier will likely not like the load in the midrange. You are likely at a half-ohm load in the midrange on your design.

I would recommend using a series resistor between the 50uF and the input from the amp of about 10-15 ohms, and just eliminate the 1 ohm altogether, or ratchet it up and the recommended series resistor down until you get the balance you want. If you use a notch filter to tame the issue above 10k, it won't come back in too much.

I strongly advise you to change the padding on the midrange, as this could be a loss of dwelling if these are run hard.

Later,
Wolf

 

[hahbs]

Thanks for the input.

I sim'd up putting a 2-3 ohm series resistor before the 50u, changed the 50u to a 30u, and changed the parallel inductor to .3m. Impedance definitely looks better and the response is nice and flat.

Should I give this a try?

 

[wolf_teeth]

Is the 1 ohm resistor still there? If not, or you have increased the value considerably, then yes you can give it a try. I still think you'll have to notch the ringing on the midrange.

Later,
Wolf

 

[sreten]

Hi,

That x/o in one technical respect is utterly awful.
Find the dreadful mistake and fix it, properly.

rgds, sreten.

 

[CraigSu]

The "egg crate foamy stuff" isn't very useful. I figured I'd say it before Dave from planet10 chimed in. If you can replace it with better insulation like the denim-based Ultratouch then the sound should tighten up. Also, if you can seal the MDF on the inside with even thinned white glue that will also help. You've gotten off to a terrific start! Now comes the fine tuning...

Re: your listening setup it appears that it's somewhat nearfield. If so, then you might try listening to your TV without a center channel speaker before you build a new one. You'll probably find that your new mains will render it unnecessary.

 

[ODougbo]

I'm not usually the wet blanket but I know many are thinking that drivers mounted on a flush baffle would provide better results and greater efficiency.
It wouldn't take long to run the speaker down the saw and replace the front battle board.

 

[hahbs]

I'll order some XO parts and tinker with it a bit. The changes I mentioned were without the parallel 1 Ohm.

I've been running them slightly higher than moderate levels. 1 Ohm resistor is not running hot. Amp does feel a little warmer and I'm keeping a fan on it for the time being.

I'm curious why the egg foamy stuff isn't useful. Not as good? Or utterly useless? With a statement like that I imagine there is some evidence. I'll look around or if you share it here I'd be happy to look at it and make the changes.

After I'm done tweaking with the XO I'll fix the baffle.

Here is an updated measurement. 40" and ear level. Not sure why it's falling off at the high end. Using a UMM-6.

 

[planet10]

I'm not usually the wet blanket but I know many are thinking that drivers mounted on a flush baffle would provide better results and greater efficiency.

+1 (sort of).

Flush mounting should reduce colouration, but won't affect efficiency.

dave

 

[CraigSu]

I'm curious why the egg foamy stuff isn't useful. Not as good? Or utterly useless? With a statement like that I imagine there is some evidence. I'll look around or if you share it here I'd be happy to look at it and make the changes.

Check out the following link:

http://www.diyaudio.com/forums/multi-way/269516-how-much-foam-lining-speaker.html

I apologize for making such a blanket statement about the eggcrate foam as I was focused on the open cell type that mattress toppers and packing materials tend to be made of. The eggcrate foam does have an effect if it's the right type of foam and applied in a manner that produces the intended results. The aforementioned thread also has additional links that can help you with your choice of stuffing or damping materials.

If Dave or anyone else wishes to jump in and provide more references, please feel free to do so. I'm still working my way through a lot of this myself.