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#21 of 1248 Chris Keen

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Posted August 26 2002 - 04:37 PM

Colin,

How about constructing a Frame backing out of a rigid but light material like Aluminum? You can get Alum in various lengths and shapes. For instance, you can get it in tubes, solid cylinders, square tubes, U-channel, L-bracket, etc. It is in varios sizes too. You can purchase said alum from internet sources, or even locally from a place like Westbrook Metals.

The frame would be light and rigid, and then you can go back to using a lighter substrate like the hardboard (like pegboard without holes), or whatever else. The hardboard or plywood or whatever substrate can be mounted to the frame via bolts and nuts, and the Plas-Tex can then be mounted to the substrate. I don't know if you were planning on doing the KBK goo or painting this, or just going with the Plas-Tex alone for the surface. Then just as you mentioned before, the trimwork around the border can be mounted to the edges of the screen. Just another thought.

My DIY projects. Been drawing up dimensions on a few things:
-- A shelf to raise the T.V. up 13 inches to put my new center channel under it.
-- Stabilizers to go underneath my new tower speakers to give better side to side stability.
-- Speaker stands to mount my new rear speakers on.

Speaking of the alum. above, I'm actually thinking of using some of the 2" diameter hollow tube stuff as the "neck" of the speaker stands. They are made of 6061 alum, and can be polished pretty easily. Then doing top and bottom pedestals out of Birch plywood with veneer banding around edges and staining. Then some spikes from some place like madisound.
Chris
Marantz sr8200
Onix Rocket 750,200,250 speakers
Panasonic rp82

#22 of 1248 Mark Hayenga

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Posted August 26 2002 - 05:13 PM

Blackout cloth (15.99) + Grey Paint (9.95) + MDF (Free) =

Posted Image


Posted Image Posted Image Posted Image
"There are 10 types of people in the world: those that understand binary, and those that have friends."

#23 of 1248 Hank Frankenberg

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Posted August 27 2002 - 12:09 AM

There you are, Chris - have you decided to build a Tempest-based subwoofer? Regarding your suggestion for aluminum frame, Colin would still need a solid, smooth substrate to glue the PlasTex material to. The PlasTex is very thin - about like laminate. If he used hardboard, he'd have to countersink the mounting bolts into it. Also, he'd have to use channel or rectangular tube aluminim in order to get the strength/rigidity needed. If he used standard size hardboard or even 1/2" MDF, maybe the PlasTex material overhanging the edges would be flat enough - I just don't know.
Good idea for your surround speaker stands. Will you fill the tubes with sand or lead shot for stability and mass? I forgot - do you have small children? If so, I really recommend filling the tubes. Also, good old MDF makes great stabilizing bottom plates for tower speakers. When you're ready, I've got the table saw and router table (if you want roundover or other decorative edges).

Colin: what'll it be?

#24 of 1248 Jeff Meininger

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Posted August 27 2002 - 07:00 AM

Jonathan, Mark:

Egad! So my AVA250 + 85 liter sealed shiva plan is no good? Bummer.

I'll be running a high crossover (120 Hz) because of my small mains. I've been told that a 15" sub will overwhelm my mains, and they won't blend as well as a good 12".

The room is on the largish side, with lots of big openings and a high ceiling. Everyone tells me that a tempest is the best match for the size of my room, but it's also been suggested to me that 120 Hz is too high of a crossover for even the Tempest to deal with properly. Then again, I've read that the Tempest is clean to 400 Hz.

What do you guys think is my best bet driver/enclosure for good, clean bass in a sonosub crossed over at 120 Hz?

#25 of 1248 mike_decock

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Posted August 27 2002 - 07:17 AM

Quote:
I'll be running a high crossover (120 Hz) because of my small mains.


I don't think it's a matter of the sub being clean at that range, it's a matter of bass being too directional above 60Hz. The sub will draw attention to it's location rather than blending into the overall sound.

-Mike...

#26 of 1248 Hank Frankenberg

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Posted August 27 2002 - 07:44 AM

Mike is spot on. Directionality can set in around 80-100 Hz. My ported Tempest tuned to 17.5 Hz sounds great. Regarding overwhelming, you can always turn the sub amp gain down for music listening - that's what I do.

#27 of 1248 Jeff Meininger

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Posted August 27 2002 - 07:52 AM

Yeah, it's far from an ideal situation. I have to put my sub front-and-center due to the directional sound you speak of. The mains are small... the woofers are only 4". The speaker manual indicates frequency response of 80 Hz - 20 kHz, and suggests a crossover of 100 to 120 Hz. With my current POS sub placed on a corner to the left of the room, the distraction factor is absolutely terrible. The huge amount of distortion probably doesn't help. Posted Image Anyway, the sub front-and-center is still quite directional, but at least not so distracting. It's a compromise I have to live with until we move to a different house one day.

I want to build the best sub for my small-mains/high-crossover situation. Is that a Shiva or a Tempest? Or something else? Sealed or vented? I'm 100% open to suggestions.

#28 of 1248 mike_decock

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Posted August 27 2002 - 07:59 AM

Quote:
The mains are small... the woofers are only 4".


Personally, I would be looking at upgrading the mains. There's some pretty good speaker kits like the GR Research A/V 1 that'll go down to 55-60 Hz comfortably for about the cost of a powered subwoofer. So you won't have really DEEP bass, but the overall sound would be better.

-Mike...

#29 of 1248 Jeff Meininger

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Posted August 27 2002 - 08:17 AM

You don't know how badly my current subwoofer sucks. Posted Image It is easily the weak link in my current setup. The main speakers ARE too small, but I'm not dissatisfied with their performance otherwise. I can live with the directional bass if I put the subwoofer where it doesn't distract me. My current sub produces way too much distortion, though. It's way too boomy and sounds terrible with music. I want something tighter, cleaner, and with more output.

One day we'll move, and I'll start from scratch with good full-range main and surround speakers. I'll then build another subwoofer optimized for that setup. In the meantime, I'm going to try to make the best of what I've got... even if that means the sub I'll build now will be a "throwaway".

#30 of 1248 Jonathan DA

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Posted August 27 2002 - 09:18 AM

Jeff,
What's your budget? If you can afford it, the 15" Lambda Acoustics drivers are about as good as it gets with regards to tight, clean, low, loud bass drivers that can also be used well past a 120Hz crossover point. I have a Lambda 12" driver that can run as high as 600Hz cleanly.

#31 of 1248 Jeff Meininger

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Posted August 27 2002 - 09:52 AM

My budget for everything (driver, amp, sonotube/MDF/polyfill/etc) is $400. I already have plenty of wood glue, wood screws, spray adhesive, and some silicon caulk. I'll spraypaint the MDF caps and cover the tube with a "sock". Should be simple sinceu there is no port to worry about.

I assume you're talking about the "SB12" and "SB15" drivers, $179 and $199 at stryke?

So many drivers to choose from... I'm getting more confused by the minute.Posted Image

#32 of 1248 Chris Keen

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Posted August 27 2002 - 10:19 PM

Hank,

Yes, the plan is to do the sandfill in the tubes. Otherwise I think they would tend to resonate. Leadshot is a neat sounding alternative, but is there any benefit of lead over sand? Sand you can pick up at Home Depot, I don't know where to get leadfill. I'm also inclined to think the sand is cheaper - always a plus.

Tempest DIY subwoofer. This one is a definite. In fact, I only need to decide on tube based (easier to build) or cube based. I'm still playing with different dimensions and such. I've been sketching out some possibilities. BTW Hank, I will almost certainly need your assistance for table-saw accurate cuts, and construction pointers, if you don't mind.

Also, Hank, do you order your veneers from a particular place, or buy them local? I went (yesterday) by a place called Fine Woods a few turns off of Cameron Rd. They have some really nice wood there. Lots of nicer hardwoods in various sizes. Great selection of hardwood plywoods. Marine grade materials, 13-ply birch, etc. They have some great euro-hinges, ball-bearing slides, etc. Extremely high quality. The guys there were nice and friendly too. They also carry veneers, but only stock about 10 or so different types, and their sizes are 2x8 sheets. They don't carry any rosewood, but said they can order it. I'm reluctant to think the 2x8 sheet would be sized good for me. Especially since the grain runs across where my bends would be.
Chris
Marantz sr8200
Onix Rocket 750,200,250 speakers
Panasonic rp82

#33 of 1248 Hank Frankenberg

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Posted August 28 2002 - 01:01 AM

Jeff, I would also have suggested upgrading your mains, but I do understand your long-range plan. It appears from your writing that you don't want the ultimate sub at this time, so I would suggest a sub (either traditional cabinet or sonosub) built around the Adire Audio Shiva 12" driver. My sub is an Adire Tempest 15" in a 24" dia. sonotube enclosure. Another good value 12" is the P.E. Dayton DVC 12". Based on your budget, I think the Adire or Dayton drivers are your choice. What do you think, Jonathan? At this point, I'd do a ported enclosure. If you're dealing with a constrained enclosure size situation, a small sealed my work. What are your goals/limitations? WAF to consider?
You're welcome to come over and look/listen to my Tempest sonosub, as Chris did last week. Looks like he's planning to build something soon. Pics of my sub are in my low-end website: http://wwww.geocitie...ond1/index.html
BTW, if you do a sonosub, I've got extra grey, unbacked carpet material that I covered my tube with. Also, I spray painted my end caps and amp enclosure with the fleckstone textured spray paint from Home Depot/Lowes.



#34 of 1248 Hank Frankenberg

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Posted August 28 2002 - 01:21 AM

Chris: lead shot will be quite a bit heavier for ultimate mass. Buy it at your favorite gun shop (McBride's?). It will cost more than sand. I was thinking more of stability (more small child proof) than sonic difference between sand and lead shot.

Tempest enclosure. Go to the Adire Audio website and download the Tempest applications, study them and pick one of their designs based on your sonic requirements and size constraints: http://www.adireaudi...empest_apps.htm

Fine Lumber is a good place for hardwood and hardwood faced plywood as well as solid core plywood, and I just bought some quality 3/4" and 1/2" MDF there. Their veneer selection is limited and they only have the 2' x 8' sheets and like other local sources it is expensive. I have a couple of out of state sources I can recommend. As I said, I can't absolutely recommend veneering the cardboard sonotube, but it may work. There are nice examples of box-type sub cabinets on threads on the various forums, so you can make it look more like a piece of furniture if you can do the woodworking. It's all a series of tradeoffs and decision points. The end result, with movies, is a smile as your guests' jaws drop at the U571 depth charge scene. Posted Image That's assuming your listening will be 50%+ movies. If you're mainly into 2-channel music, that's another conversation.

#35 of 1248 Jeff Meininger

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Posted August 28 2002 - 01:37 AM

Here are my requirements:

1. I want a downfiring sonosub, not a box. I like how they look, they're easier to build than boxes, and WAF will be higher with a smaller footprint considering the front-and-center position of the sub. This limits me to drivers rated for downfiring applications.

2. I want tight, clean bass. My current 8" POS is very boomy, makes lots of coke-bottle port noise, and produces plenty of distortion. It sticks out like a sore thumb. Contentional wisdom says that a sealed enclosure is the best choice for tight, clean bass. I think this will be especially important with my high (100/120 Hz) crossover as the sub will be responsible for a larger-than-usual range of frequencies. As I understand it, group delay is about playing multiple distinct pitches clearly. So I'm pretty sure I want a sealed sub based on what I've read.

3. $400 budget for driver/amp/sonotube/MDF. I have most of the other misc. stuff.

Deep extension and more SPL would be gravy. Sure I want them, but I'm not listing them as requirements. A sealed sub generally trades these things off for clarity, which is fine with me. Perhaps at 3 dB boost at 25 Hz soldered onto the PE 250W plate amp would help counteract the natural rolloff. My primary concern is tight, clean, non-boomy, non-distorted bass though. Something that will blend as well as possible with my speakers.

My plan started as a 79L sealed shiva, and moved up to 85L after speaking with Adire:
http://www.hometheat....?postid=928975

But then this thread made me rethink. Jonathan and Mark said they steer people away from sealed shivas, and that there are better drivers available for that.

#36 of 1248 Hank Frankenberg

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Posted August 28 2002 - 03:26 AM

Jeff: have you read through most of the sonsosub related threads?: http://members.tripo....um/page12.html

I would take Dan Wiggin's advice on design. In my amateur opinion, I think the "quick/clean/musical" differences between ported and sealed sub designs is overblown. I don't think it's a night and day difference as some people's opinions suggest (IF a ported sub is well-designed AND constructed, that is). There are many marginal design budget ported commercial subs that definetly give the impression that ported is boomy, one-note, unmusical junk.

Beyond this, I defer to the real speaker designers on our forum. If they say there's a better 12" driver for sealed applications that's affordable within your budget constraints, then heed their advice. You're welcome to come over and listen to my Tempest ported sonosub and I'll give you some construction tips and show you my drawings.

#37 of 1248 Jonathan DA

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Posted August 28 2002 - 03:36 AM

Jeff,

The Lambda drivers I was referring to are the PL series, but the SB's are great too. The PL series have a copper sleeve around the pole piece of the motor (aka a Faraday loop), which helps to reduce distortion and they can also be had with a solid Aluminum phase plug. The combination of these two features allows them to be run at higher frequencies than most subs. I have a 12" PL diver that can cleanly go up to 600Hz. However, I'm afraid the PL drivers would break your budget. The SB drivers have the same motor, but no phase plug is available. At 120Hz, though, it shouldn't matter.

The Dayton DVC and Adire drivers are virtually identical, both are made by Eminence. If you go that route I'd get which ever is cheapest.

Another good driver to consider is the Titanic 12" MkI NOT the MkII. The Mk II is best in a vented box while the MkI is a sealed box woofer.

As for group delay, don't worry about it. A well executed vented sub can sound just as musical as a sealed sub.

As for sonutube vs box, I personally prefer boxes. You can't easily veneer a tube and a big painted cylinder in my living room would clash with the rest of the decor. Plus I find boxes less visually imposing, consider the fact that for a given amount of floor space occupied, a cylinder will have to be taller than a cube in order to get the same volume.

If it were me, I'd up my budget $50, buy a Lambda SB12, and put it in a box. Actually, I'd just spend $1000 on a Mirus Audio sub, but we're talking DIY here Posted Image

#38 of 1248 Hank Frankenberg

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Posted August 29 2002 - 01:15 AM

So what brand amp does that Mirus Audio outfit provide with their subs? Posted Image Jonathan, do you guys have postable photos?

#39 of 1248 Jonathan DA

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Posted August 29 2002 - 02:29 AM

I never have liked powered subs, it amuses me that audiophiles will spend countless hours and thousands of dollars finding just the right amp to match to their main speakers, and then just accept any old plate amp stuck to the back of their sub. So...all of our subs are currently passive, and I'll obtain any amp you want for it.

Here are a couple of pictures of our smaller Cinema sub:
http://www.mirusaudi......sub back.jpg
http://www.mirusaudi.../cinema sub.jpg

It's a 10" woofer with a 15" passive radiator, anechoically flat to 30Hz (mid 20's in room), greater than 1" peak to peak excursion. I only have enough drivers in stock to build two more of this model, and then we'll probably bring out a new version with a 12" driver instead of a 10". Possibly with Lambda OEM drivers. The $1000 was more of a joke, we'll sell these for less depending on what type of amplification you want.

#40 of 1248 Brian Bunge

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Posted August 29 2002 - 03:32 AM

Since I made it to a recent Austin meet I figure I can post too, right? Posted Image

Anyway, if you do go DIY, I'd suggest giving Hank's sub a listen. I didn't hear it myself, but I built a replica in a box instead of a tube. This is one potent sub! I used a Dayton DVC 15", a 4" dual flared port, and a PE 250W plate amp.

Going with Johnathan's statement about amps:

My current subs are sealed ACI SV12's and I have been powering them with the 200W PSA-1 plate amps. I bought a Crown K2 used a few months back in anticipation for a new monster 15". I've been using it with the dual sealed subs and the difference is night and day!

Brian
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