WAF limited Sub System

[aceinc]

As I have mentioned in other posts, I embarked on a Spouse friendly Sub woofer DIY project. Pat, my wife agreed that if I could put my sub(s) in a cabinet that did not look like a speaker cabinet, and fit into the decor of our newly remodeled living room I could do whatever I wanted.

As we were looking for furniture, couches and the like, we kept an eye out for something suitable. We came across a set of three trunks that looked like they would meet my needs. Since I had three trunks and about 3,500 cubic feet of space I decided to do multiple subs with different specs. Some folks that know much more than I suggested this was a bad idea, one comment was it would dumb down the entire system to the weakest link.

I also discussed the problem with Brian Ding of Rythmik Audio, and he had similar concerns. He suggested that I attack different frequencies with the subs, so what I decided to do was build two 10" subs to handle the frequencies above 40 hz and 1 larger sub for freq's below 40hz.

The cabinets have a gross interior volume of .6 cu ft and 3.4 cu ft. So after looking around I chose the Titanic 10" drivers for my small cabinets and the new Rythmik Audio DS15 for the larger cabinet. I needed to determine the best way of powering the small subs. My problem was when I remodeled the living room I had prewired the areas where I expected to put speakers, but neglected any line level jacks. What I finally came up with was driving the small subs from a NAD amp I have and daisy chaining the DS15 off them.

I began ordering stuff, first the Titanics a BFD and some measuring equipment. I built the interior cabinet for the small subs out of 3/4" MDF. I did my cutouts in the interior cabinet first then glued the interior cabinets into the finished cabinets, using a edge trimmer/router to open thhe holes in the outer cabinets.

The cabinets went together in a weekend, and I was listening to them late Sunday night. Due to my not reading the info on the mixer I bought I did not realize it lacked Phantom Power and the ecm8000 would not work with it. So I exchanged that and by the next weekend I was testing. I found that I could get decent bass (flat) down to about 38hz, so things were looking good.

I ordered the DS15 and began building out the larger cabinet. This time I decided to glue the individual panels to the interior of the existing cabinet. I put the bottom and sides in and waited for the speaker & amp to arrive. I was up early on Thanksgiving and had the finishing touches on the cabinet after the turkey. Only one problem, I had used too much glue to attach the finished lid to the interior box. So I had to let the cabinet sit upside down over night so the glue wouldn't leak all over the cabinet.

The next morning I was ready to do testing, Pat had gone shopping so it was a perfect time. Unfortunately everyone went shopping with her, and I had put the subwoofer on a bay window sill with the help of my brother in law the previous evening, and I didn't want to try and get it down by myself (I estimate it weighs over 100 lbs). So I waited. When I finally started testing I had to convince everyone to move into the farthest part of the house. After about 3-4 hours of moving subs adjusting xover freq's phase knobs and setting up filters on the BFD I got a decent curve flat to about 15hz.

I promised some pictures in an earlier post. I warned that if I did my job right they would be pretty boring but here they are;

BTW The speakers on the window sill are some North Creek Echoes I built.

[brucek]

I promised some pictures in an earlier post

They sure look good. Great job.

I would love to see the 15Hz to 200hz overall REW plot.....

Can you explain more about crossing between the large and small subs, or are you using the natural slope of each box?

brucek

[Wayne A. Pflughaupt]

Some folks that know much more than I suggested this was a bad idea, one comment was it would dumb down the entire system to the weakest link.

That is indeed a legitimate concern. Conrats on the innovative two-stage idea! As brucek mentioned, it would be nice to see a graph, and I’d like to know more about your crossover set-up as well.

Regards,
Wayne

[Sonnie]

Very interesting setup there. I like those cabinets... definitely unique.

[aceinc]

I would have more data, but I had a swiming pool pump go up in smoke, had to install blinds, and generally do familial stuff.... I will post more data soon... I haven't really had a chance to listen to the system as much as I would like.

I also want to do more testing under different configurations. What I have at the moment is the sub out of the receiver goes into a splitter, driving both channels of the BFD. The output of the BFD goes into the NAD power amp this drives the 10" subs. These subs have a steep natural curve at about 38 hz.

I ordered the DS15 with a 24 db xover. The DS15 goes pretty flat down to 15hz, so I just needed to match the DS15 with the 10s. I attached the amplifier in the DS15 to one of the 10's. I then used REW to match the level, phase and crossover.

The next test I want to do is to send both speaker signals through the DS15 amp and then back to the 10s. I will need to rebalance everything, but what I hope to gain is a high pass filter for the 10s. This should reduce the load on the 10s. It may also give me a cleaner xover and less filters on the BFD.

Over the next few weeks I will have little time, but I will post what I can as I can.

Paul

[terry j]

congrats on a very nice looking and clever solution to the decor problem! Just out of curiosity will look with a different eye at the next furniture place I'm in.

My only problem is the wife collects antiques, can imagine the look on her face when i proudly tell her how, with the help of her latest expensive purchase I managed to 'hide the sub'!..... " But I thought you'd be pleased darling!"

[aceinc]

Terry,

Buy fake (faux) antiques. The cabinets we bought were pretty cheap. Look in places like Bell's, JC Penneys, any place they sell inexpensive furniture. We bought floor samples at a furniture store.

If I do it again, I may try to cover a Sub in Naugahyde and some Furniture nails and antique looking fittings. That way I can build the trunk to an optimal size.

BTW, I used clear liquid nails to glue the fittings down so they don't rattle.

Paul

[JCD]

Very clever! And they look great!
I'm assuming these have downward firing drivers? If so, can I see a pic of the bottom?


JCD

[aceinc]

JCD:

I used to play that game with the girl next door when I was a kid.... (I'll show you my bottom if you show me yours... )

If anyone is interested, I will post close ups (27, 8"x10" color glossy photographs.... with circles and arrows, and a paragraph on the back of each one...) when I get home.

Paul

[aceinc]

Well here are the bottoms, please shield the kid's eyes. I must admit that I didn't make the bottoms as pretty as I could, but they're the bottoms after all.

Paul