Zaph Bargain Mini Q's

Yes, I'm new here...people from Head-Fi directed me here. For my final project in woodshop, I would like to make a set of these speakers to accompany the JBL Power 20 amp I found in my basement. HOWEVER, being my first speaker build, I have some questions.

1. Where is the port exactly? On the diagram, it gives no reference points.
2. Where can I get a 1" port (with the flare at the end)?
3. What type of dampening should I go for on a budget? Zaph says carpet padding would work. I have seen chopped foam padding and just medium density foam at Home Depot. Which one is better? Or should I go for a hybrid and laminate 2 (or 3) pieces together?
4. To the people who have built Bargian Mini's, can you post a pic of your crossover? Aside from electronics in Grade 9, I have not taken any other.
5. I've decided to tweak the front a bit, so the it sits in the frame provided by the four sides. What gasket materials should I be looking at to seal the baffle? I've seen some GB Duct Seal at HD, but would silicone work better?

Thanks, Brendan :D
 
Hi Brendan

I'll try to answer a few questions.

1. I don't think the location of the port is too critical, centered on the back directly behind the tweeter should be okay.

2. The port is from Parts Express, part # 260-470.

5. Use weatherstripping from Home Depot, closed cell foam.

T-nuts are probably the easiest to use, again from Home Depot.

Hope that helps.

Bob
 

squib

Member
2007-07-10 12:52 pm
As to the port: you might be able to substitute a 1.5" diameter port, but the length will have to increase to maintain the same tuning. I would recommend holding off on the larger PVC and getting the 1" material Zaph included in the original design.

If you really want to try the larger diameter port, you can download link]WinSID[/URL].
This will allow you to model the longer port length to achieve the same tuning. You will need to input the driver T/S parameters, but it's not that difficult to sort.

Your chosen starting point of using a proven design is a good one...just be careful when making changes, as a seemingly small alteration may have profound effects on the final sound of your project.

Good luck,
Squib
 

squib

Member
2007-07-10 12:52 pm
damping material

Carpet padding works relatively well. You can also fine various densities of open cell foam in the crafts sections of big box stores. For example: Polyurethane foam blocks sold for chair pads (1-2" thickness). It's generally pretty inexpensive and easy to work with, just keep it away from open flames :) .
 
cyberspyder said:
Can't edit yet :mad: BTW, what type of wood inserts should I be looking at for the baffle screws? I was thinking of using some big Torx/Socket cap flathead screws along with T-nuts or threaded wood inserts.

Hi,

I suggest you reread the article very carefully. With an MDF baffle
all you need is drilled pilot holes for self tappers or something similar.


cyberspyder said:
Can I use a 1 1/2" port instead of the 1"? I can't find a 1" PVC tube locally (at homedepot or Rona).

Port is 1" internal diameter. 1.5" internal will be too long to fit inside.

:)/sreten.
 
Oh, BTW I can't use MDF at school because of the dust. We DO have a dust collector, but I have to cut it afterschool, thus limiting the amount of time I get. My alternative is 3/4" Baltic birch/Russian plywood. Upon further searching, I found a 1" port tube at Parts Express, so that's taken care of. Based on my teacher's opinion, the inserts aren't needed, since I won't be taking out the screws or screwing it in often (once or twice max.). Last question, other than weather stripping, can I use silicone (for the baffle gasket)?
 

squib

Member
2007-07-10 12:52 pm
You can use silicone to make a gasket that doesn't "glue" your driver the the baffle.
Lay the baffle flat, with the front facing upwards.
Lay a bead of silicone down on the baffle.
Lubricate the driver flange with oil.
Place the driver in position and let gravity flatten the silicone.
Let the silicone cure for at least 12hrs, then remove the driver.

This should leave a "custom" gasket on your baffle that conforms to the driver flange, but still allows you to remove the unit if you need to make any adjustments.

You can find a couple of variations on this procedure posted in these forums.
 

squib

Member
2007-07-10 12:52 pm
I've not tried the technique for attaching the front/back baffle to the rest of the enclosure. Perhaps someone else will chime in. If you do decide to attempt it, keep in mind that you will have to seal the edges of your wood (MDF, Ply, etc) to keep the oil from soaking into the material.

You can get some general pointers from Weems: Designing, Building, & Testing your own Speaker System. Now available on google Books:

weems on silicone for enclosures and gaskets

Hope this helps.
 
oh virtual octapod,

The owens corning product you linked is not suited for damping. The face of that material is reflective...it will keep the sound waves bouncing around in your enclosure. Better choices are polyfil from the crafts section of your favorite "big box" retailer or acoustic ceiling tiles (look for the ones with spun fiberglass insulation) from the building suppliers.
 
Zaph used PartsExpress' "Sonic Barrier" acoustic foam (http://www.partsexpress.com/webpage.cfm?&WebPage_ID=3) which is much different than the rigid foam that you've linked to. The purpose of the foam or damping is to absorb the sound within the enclosure; rigid foam would reflect it. You could also use pillow stuffing, regular "pink" fiberglass wall insulation (like Tenson suggested), etc.

Note that the amount and location of damping is a significant part of the enclosure's design. You'll have to be prepared to experiment with various amounts of it if you stray from what Zaph used. (Not that there's anything wrong with that!).