Active Bookshelf Speaker build Dayton RS-180 & DC28FS

[annunaki]

So I wanted to do a set of bookshelf speakers on the cheap, yet deliver reasonably good performance. I have a Behringer DC2496 that is only taking care of a sub right now, as well as extra amplifier channels available. I might as well put them to good use.

The enclosures are sealed and offer about .4ft^3 after displacement placing my modeled anechoic f3 at around 72hz.

Below is some of my build progress so far. They will eventually be finished in a hammered texture black to match my subwoofer. I will also be building a matching center channel.

Going active, my target x-over point will be around 2Khz with an additional 4th order notch filter added on the woofer around 3Khz to ensure the cone breakup is well below audible. It will take some time to tune correctly but my target predictions look to bring good results.

2" rockwool added:

Center Brace added:

More to follow...

 

[Alex2507]

Too many braces ... Love these threads. Thanks.

 

[jamie2112]

Nice work that looks super heavy duty.......no cabinet res there!!!

 

[annunaki]

Nice work that looks super heavy duty.......no cabinet res there!!!

There will still be some but definitely minimal. There is no area over 5" that is unbraced internally. Construction is sturdy, but constrained layer damping is the best at combating resonances. I did not want to invest that much into these as I am trying to keep the cost lower.

 

[Rickster71]

Nice!
What drivers are you using?

 

[Rickster71]

Duh...I didn't see the thread title until now. Never mind.

 

[lsiberian]

Too many braces ... Love these threads. Thanks.

No such thing, but I do think it's very impressive. what cloth are you covering the treatments with. I really like the look of it and need to get off my lazy butt and get something so I can continue on in the project.

 

[annunaki]

No such thing, but I do think it's very impressive. what cloth are you covering the treatments with. I really like the look of it and need to get off my lazy butt and get something so I can continue on in the project.

I am covering it with black PE grille cloth, simple, inexpensive, yet very effective.

 

[annunaki]

Here are some further updates on my "what seems to be taking forever" progress.

Test fitting the drivers in the baffle:

Some internal shots:

Shot of baffle prior to attachment:

Baffles completely attached:

Roundovers completed and holes filled and sanded:

 

[Alex2507]

Fallen One,

How do you go about calculating the effect of the insulation on Vb?

 

[adwilk]

This is the type of thread that makes me realize that whatever speaker I may eventually build will be inadequate...


Nice work... Looks great...

 

[annunaki]

This is the type of thread that makes me realize that whatever speaker I may eventually build will be inadequate...


Nice work... Looks great...

Thanks for the compliments, but this is a fairly simple build all around, being sealed. Not sure what experience you have, but with a kit, one can easily make the cabinet modifications with a little bit of forethought and planning.

 

[annunaki]

Fallen One,

How do you go about calculating the effect of the insulation on Vb?

Fallen one? LOL nice

Actually with rock wool/mineral wool sheets they have a minimal effect on volume, but large impacts on internal cabinet reflections. I did allow for about .06-.07ft^3 displacement of the mineral wool sheets.

I cannot wait to get these up & running though. I am anxiously awaiting my first impressions.

 

[lsiberian]

This is the type of thread that makes me realize that whatever speaker I may eventually build will be inadequate...


Nice work... Looks great...

It's actually pretty simple as long as you can cut squarely. It does take time and hard work though.

 

[Alex2507]

Fallen one? LOL nice

It's a hard myth to nail down but I do like a good story.

Anyway, I take it that you are using more than 0.06-0.07 ft^3 of mineral wool?
I don't have a calculator handy to figure out the square inches involved.

I had WmAx say to use 5% and 10% of the volume of 703 and 705 respectively to deduct from the internal volume of a cabinet and was looking for some confirmation on this approach.

 

[annunaki]

It's a hard myth to nail down but I do like a good story.

Anyway, I take it that you are using more than 0.06-0.07 ft^3 of mineral wool?
I don't have a calculator handy to figure out the square inches involved.

I had WmAx say to use 5% and 10% of the volume of 703 and 705 respectively to deduct from the internal volume of a cabinet and was looking for some confirmation on this approach.

Wmax's calculation is about right.

The physical size of the mineral wool appears to occupy more volume than that but its effective displacement is significantly lower.

As for the story you may also want to reference here and look for books. This is also intriguing.

 

[GO-NAD!]

Looks like a nice project. I had no idea you had such a complicated background...

 

[lsiberian]

Wmax's calculation is about right.

The physical size of the mineral wool appears to occupy more volume than that but its effective displacement is significantly lower.

As for the story you may also want to reference here and look for books. This is also intriguing.

I don't even go to that depth honestly. I know it's wrong but I figure with my woodworking skills close enough will be fine. What amp modules are you using?

I've been thinking of building something like this http://www.electronics123.com/s.nl;jsessionid=0a0103571f43e0d24ecc2c0946afa567984c1b3c0b18.e3eScheKb3qRe34Pa38Ta38LbNr0?it=A&id=328

or going with a chip amp.

 

[WmAx]

The insulation can be problematic when using high density material such as this. But in the moderate amount used above, it will have very little effect; really inconsequential. In the amounts I use, to produce a totally inert acoustic space for zero coloration; it actually causes critical damping of the driver, making it act much like it would in an IB; early pronounced roll off even starting at about 300-400Hz by a dB or 2.

The above picture shows stuffing before back is installed, and before final insulation is placed in the small empty areas still empty. Imagine 90 percent of internal volume stuffed with high density OC705 or Roxul #8.

-Chris

 

[annunaki]

I finally found some time to post some updates of my progress!

I actually have these finished sans the grilles but here are the photos I have taken up to that point.

They do sound quite good, but I need some tweaks as to my baffle step correction and tiny adjustments to overall tweeter level, etc. Thankfully this is easy to do with an active setup.

All in all I am pretty pleased. The amount of detail I am noticing is quite nice

I have not weighed them yet but best estimates are that they net in a bit over 30lbs each.

Here is a picture taken during painting:

Binding posts installed:

Enclosures after painting and masking removed:

Wiring installed into enclosure: