Calculate enclosure for 15 inch sonotube...again

[chasw98]

Thanks, again. One less step in completing this project.

[chasw98]

I have put it together, sealed the top plate and it is in use! I have some minor things to work on (ran out of paint after doing 2 out of 4 legs, some polishing here and there). I am running REW and will post some graphs as I soon as I figure out how to capture them. First impressions.... WOW, it sounds great! Thanks Steve. Thanks Thomas. I never would have believed that I could get this response and sound from a $100.00 driver.

Chuck

[chasw98]

Here are the graphs I come up with from REW. First is response, no EQ. 2nd is EQ. Do they look OK?

[ThomasW]

The second one looks about as good as one can get.... :T

[SteveCallas]

I agree - that FR with the EQ looks darn near perfect. It's basically indentical to what WinISD predicted too. Awesome job.

If you don't mind me asking, what did the whole thing run you not counting the amp (I believe you already had it), maybe $300 tops? That 15" DVC appears to be one hell of a bang for the buck.

[chasw98]

Here is the final parts list with cost.

Sonotube 4 feet 20" diam. - $33.09 Hughes Supply
Acoustic Foam w/adhesive - $45.00 ebay
Auto Headliner - $42.28 autoheadliner.com
Input cup & Port grill - $13.37 Adire Audio on ebay
Dayton 15" DVC driver - $118.20 Parts Express
Paint, Adhesives, Router bit, MDF, etc. - $102.51 Sears, Home Depot, Lowes
6 inch sewer pipe for port - $0.00 from work

Total Cost - $354.45

Note: I had to buy 12 feet of sonotube which cost a total of $99.28 with company discount. I have 8 feet left over for another one. I could have saved money on the acoustic foam and the headliner, but it was available now, so I bought it.

Behringer EP2500 - $279.99 ebay
Behringer BFD - $66.00 ebay

Total - $700.44

In the end, I would have bought a better driver if they were available. I have heard this driver "bottom out" (on WOTW & Serenity) at level setting of 85 db SPL (quite loud in my room). But I feel this is an incredible piece of equipment that I built and would have cost far more for less performance had I bought a commercial unit. I get a 15" driver (most commercial use 12's in this range) and an amplifier rated at 2400 wrms mono/4 ohms, 650/stereo (far more than most all in one units). I also have an enclosure that I can upgrade to a better driver when they are available. With the help of Thomas & Steve, I have learned a little bit about the modeling process, port design and selection. I am very happy with the unit. Thank you all. :T ;x(

Chuck

[chasw98]

Well, disaster has struck. I was watching the movie Serenity just now. In the opening of the movie right after the Universal theme song, a shot of a planet viewed from space comes up with bursts of light on the planets surface. Each burst of light is accompanied by a very deep bass note. After 3 or 4 of these the woofer went dead. I checked the voice coils with my Fluke meter and they are open! I do not believe I had the system turned up very loud, but it was loud enough for these notes to open up the voice coils. I guess I will be on the phone to Parts Express Monday AM to get another one. what is the chance that I got a defective unit? If not defective, is it so sensitive that I popped the driver so quickly and apparently, easily? Honestly, I was not going for +100 db levels, far from it. ops:

[SteveCallas]

Was the driver bottoming or in distress before it went dead? Though it may not have seemed that loud, really low stuff can play pretty loud before you notice it. You'll definitely want to look into a high pass filter when you get it fixed - that amp has more than enough juice to run that driver into overexcursion when you start getting below 20hz.

[chasw98]

Was the driver bottoming or in distress before it went dead? Though it may not have seemed that loud, really low stuff can play pretty loud before you notice it. You'll definitely want to look into a high pass filter when you get it fixed - that amp has more than enough juice to run that driver into overexcursion when you start getting below 20hz.

It did not sound in distress, but I could hear a "braaapppp" as those notes struck and immediately lowered the volume. Just right before Serenity I has listened to chapter 5 the machine emerges from WOTW and everything sounded fine.

[ThomasW]

You're running a EP-2500?

Remove the driver and smell around the magnet. Smell burnt?

[chasw98]

You're running a EP-2500?

Remove the driver and smell around the magnet. Smell burnt?

No, it does not smell burnt. My son, wife and myself just sniffed it.
The sub is using just one channel of the EP-2500 with the dual 8 ohm VC wired in parallel.

[ThomasW]

Since it doesn't smell burnt you stand a chance of getting it replaced as defective.

"braaapppp" is usually the noise of the VC former hitting the backplate

At 4 ohms you're looking at 750 watts available. The Pmax of the driver 600 watts .

My guess is that you heated up the VC with WOTW and blew it with the opening of Serenity

[chasw98]

I will try and get it replaced as defective. How do I prevent this from happening in the future. Turn it down would be the first suggestion probably. I am building a hi pass filter as we speak. Thanks for the help once again.

[ThomasW]

Some of the new movies are killers for less than over-the-top woofers. Remember that WOTW as significant 3Hz content, and the DVC 15 is a fairly modest woofer.

Options......

1) use a more manly driver, (RL-p 15" for example)
2) second use an amp that's power output is lower than the drivers Pmax.
3) use a lower box tuning,
4) use a sealed box, though the drivers can 'oil-can' = blow the VC out of the gap at high excursion.

[chasw98]

Some of the new movies are killers for less than over-the-top woofers. Remember that WOTW as significant 3Hz content, and the DVC 15 is a fairly modest woofer.

Options......

1) use a more manly driver, (RL-p 15" for example)
2) second use an amp that's power output is lower than the drivers Pmax.
3) use a lower box tuning,
4) use a sealed box, though the drivers can 'oil-can' = blow the VC out of the gap at high excursion.

#1 I am thinking of going that route. Depends on Parts Express.
#2 Through the use of impedance I can probably do that, i.e. 2 4 ohm VC in series as opposed to parallel.
#3 will be tough but doable
#4 probably not since it is built, but next time...
Ahhh... live and learn

[J-Dub]

Sorry to impose but, any word on the RL-p15's availability any time soon or still a month+ ?

[ThomasW]

We don't have any inside info so probably best to contact Chris at SS.

[chasw98]

I just (by mistake) placed an order for an RL-p15 dual 4 ohm model. The dual 2 are out of stock. I have talked to Mike in the past, so I will call tomorrow and see what he has to say.

[Joe L.]

Joe L. has pictures of it on his sonosub construction - those might be the pictures you are thinking of. I wrapped my port as well, with about 8 layers of 1" thick poly batting.

The reason I have batting/fiberfill at the end of my sonosub with my port is that I wanted to reduce any standing waves inside of my enclosure since it is so long. It had nothing to do with the "port" itself. Your enclosure is nowhere near as long, it would not be appropriate.

Sorry to learn of the demise of your driver. Hopefully, you will soon have the subwoofer back on-line. (Serenity and WOTW really put these subs through their paces.) WOTW probably weakened the tinsel leads to the voicecoil and Serenity provided the final blow.

Hope you can get it covered under warantee.

Joe L.

[chasw98]

I contacted Parts Express yesterday morning. The lady on the phone said a tech would check the driver out when it was returned. I shipped it back UPS. She seemed confident that they would take it back and give me a refund, but I will see once they get it. I have contacted Mike at Soundsplinter and a new RL-p15 dual 4 ohm is on the way. It will be here before the weekend. Knowing that I have a EP2500, enclosure with 7.75 cu ft., port 27.5 inches long X 6 inch diameter, and an RL-p15, how would you utilize these components as far as wiring the driver to the amp. There are 3 choices: wire 2 4 ohm VC in series for 8 ohms with 1 channel of amp (not bridged), wire each VC to a channel of the amplifier, or wire the VC in parallel (2 ohms) to one channel of the amp. I have immediately thrown out the third option. What is your opinion Thomas? Thanks

[ThomasW]

Make life easy, wire one VC to each channel of the amp.

[chasw98]

Thank you. I was hoping that would be your recommendation.

[chasw98]

I recieved my RL-p15 today. I had to enlarge the cutout in the bottom plate to accomadate it, but all is well. It is installed and working I am GENTLY breaking it in with the amplifier at half gain and listening to slight rumbling to exercise the driver. It sounds deeper and smoother than the dayton DVC but I haven't taken any measurements yet, so I 'm not sure. What I have heard is like a brand new 350 with triple deuces idling and warming up just waiting for the chance to go down the highway in the open air! here are some shots of the acoustic foam and the driver and the finished product. Thanks to Thomas and Steve or I never would have built this good a unit.

Chuck ;x(

[SteveCallas]

Nice - that acoustic foam shot looks really cool. You made a conscious decision earlier to go the cheap route to gain experience and instead you have ended up with a pretty badass sub that should be able to handle most anything you toss at it. Is the 17hz rumble filter installed?

[steve nn]

WOW! Very nice. Cant wait for you to getter up and going.

I still have an extra RL-p sitting here waiting to see if it'll be needed for another project or not. If it's not..I feel a Tube coming on.

Nice work Chuck and kudos' to Steve C. It looks great!

[ThomasW]

You don't need to be too gentle with your new driver. It's got double spiders, a stiff suspension and is designed to take a pounding ...... :T

[chasw98]

SteveC:
The rumble filter is in the final stage. I have some DC voltage on the output (probably from a solder bridge) and need to double check my work. Probably be working tonight.

Steven:
I've got extra sonotube, or you could sell me your extra RL-p15 so I could run duals.

Thomas:
You don't need to be too gentle with your new driver. It's got double spiders, a stiff suspension and is designed to take a pounding ......

I am not going to pound it immediately. I will wait and get the filter in place and exercise the driver for a few hours before ummmm, pounding it!

I will be taking some measurements Friday night and will post them later. Just from initial listening last night, I believe this response will be as good if not better than the DVC. Thanks to all for your help :

[ThomasW]

I believe this response will be as good if not better than the DVC. Thanks to all for your help

Well you upgraded to a Ford GT from a Mustang ....

[chasw98]

Here you are. Initial before and after EQ graphs. I was able to get it much flatter in the 20- 100 range but there is some "stuff" at the upper end.

[chasw98]

Here is the 17 Hz Hi Pass Filter. In these pictures you will see the signal generator and my fluke 79 which has a freq counter built in. Notice 1 volt AC at 170 Hz and .4 something VAC at 17 Hz. The filter apparently works! I have not checked S/N or distortion yet. Oh and whoever can tell me what model HP is in the photo wins a prize! I bet Jon and Thomas can.

[chasw98]

Here are pictures of the filter itself and my test rig.

[ThomasW]

Oh and whoever can tell me what model HP is in the photo wins a prize! I bet Jon and Thomas can.

Jon can cause he's really old .... :B

[Dennis H]

Dang, Chas, that's really impressive response after EQ. It doesn't get any better than that. Well done! :T

[SteveCallas]

Like I mentioned before, you can make a LOT of people jealous with that FR. Great, just great. I like how the box is clearly labled "17hz Hi Pass Filter", you know, just in case you forgot :T

[chasw98]

Jon can cause he's really old .... :B

And what does that make me for owning the relic?

[bobgpsr]

Oh and whoever can tell me what model HP is in the photo wins a prize! I bet Jon and Thomas can.

It looks very very similar to my Waveforms, Inc. model 401B Oscillator. Your middle knob is just a little bit higher. Mine are all in line. I got mine used back in the '70s. It still works although I normally use a PC soundcard to generate sine waves now.

Bob

------------------------
My current (just started - parts ordered) Adire Tumult 15" driver with two AE 18" passive radiators DIY subwoofer project:

http://hometown.aol.com/bobgpsr/myhomepage/profile.html

[chasw98]

Good try, Bob. It's a Hewlett Packard 200CD.

[chasw98]

A final note. Parts Express has given me a full refund for the 15" DVC driver I started with. They did not give me a reason for the refund but they credited my charge card in full. No problems. I can't recommend them enough!

Chuck

[---k---]

Thats great news.


So Chas, when you going to add your sub to the DIY Subwoofer Showcase thread? I think your's would be a great addition since so many people are interested in the RL-P15 right now.

[chasw98]

I will be posting there. I have to put some pictures on photo-bucket, get some better FR graphs, and just do it. But I will, you'll see!

Chuck

[---k---]

Cool.

You don't need photo-bucket. You can just use the like to the photos above. Like this:



And, you can always post what you've got and go back and edit later to add the measurements and whatever else. I just updated the photos on mine to show the new paint job.

I'll leave you alone now and go bug stevenn about adding his.