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Discussion Starter · #1 ·
Hi guys,

First post here...found this site searching for DIY subwoofer info. Lot's of cool stuff here and am learning a lot. I'm still weighing my options for my own, but I am leaning towards building a push push sub for my revamped HT based on the 8" Tang Bang W8-740P. I'll be driving them with a 200watt Eosone 2 ohm amp. The drivers are 4 ohm and will be wired in parallel. Partsexpress has the TB's on special right now and they look like fun!...I bought two. The reviews are short on info, but good.

Anybody building something with these drivers?..or any tips on push push designs.

Warmon -
 

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Hi Warmon and welcome to the Shack! Glad you found us... :T

I know someone is using the Tang Bang drivers in a DIY speaker project, but I'm not sure about any sub projects going on. I believe one of our members is building a push push design using larger drivers. You might check out his thread to get some ideas on a similar design.

We would certainly love to follow your progress and pictures as you build. If you need any images hosted for posting in threads, we can host those in our Image Gallery for you - it's free!
 

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Welcome aboard Warmon.

I have a pair of 8" tang band drivers (definitely not the same model you have) laying around. They were from a a pair of logitech z560's we used in our computer rooms. Each amp died around the same time...what a coincidence :bigsmile:

Anyway, im not entirely sure if its true but I was under the impression that these push push subs work well when the drivers are opposite eachother. The purpose of this is to help minimize enclosure vibrations :) Decreasing the need to build an incredibly super rigid enclosure.
 

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Discussion Starter · #4 ·
Thanks for the warm welcome guys...:yay:

Yes, from my understanding the whole point of the push push design is to cancel out resonance from the enclosure with minimal internal bracing. They are firing back to back. Below is a design by Dave Dlugos using the Apex Jr, Super 8. This is my inspiration. But, I have some design hurdles to over come using the Tang Bands as both drivers in a vented box require close to 0.7 cubic feet [Vb].

http://www.apexjr.com/images/Super8PPBR.gif

Warmon -
 

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Discussion Starter · #5 ·
Well fellas, the BBT dropped off my order from PartsExpress late yesterday. Here's the W8-740P's - time to get serious about my final design...:mooooh:

Warmon -
 

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I'm curious to see how this turns out. I have a couple of these drivers that were going to go into a set of stereo speakers that didn't pan out. I figure I'll use them for a subwoofer for the stereo in the bedroom.
 

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Just a question why a push push design? I do understand that you want to reduce cabinet vibrations but why not simply brace you box? I might be wrong but the displacement of those drivers being run from 200 watts is hardly wall shattering power! I am not familiar with that Amp however from experience even with pro audio amps running an amp at two ohm is risky business, also that amp is going to clip trying to run those drivers which are rated at 150 RMS each, i really do think you need to think about budgeting for a bigger anp that you can run at 8ohm rather than 2! Even a large vented box for those drivers will still be reasonably small so if i were you id design a large vented box with two forward facing woofers. Either way good luck with your constuction

Regardless please post contruction photos, they give me that warm fuzzy feeling :T

Oh and what are those drivers sitting on :dunno: looks like a box...
 

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Discussion Starter · #8 ·
I'm curious to see how this turns out. I have a couple of these drivers that were going to go into a set of stereo speakers that didn't pan out. I figure I'll use them for a subwoofer for the stereo in the bedroom.
Hi Geoff. How's your push push tv stand project coming along? Do you have all the TS parameters for these TB's?. I get very different results in WinISD comparing the 740C's and just entering the basics for the 740P's.

Warmon -
 

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The stand's coming along nicely. Hopefully I'll have time to put it in place tomorrow.

I haven't looked for any complete specs for my two subwoofers yet. I have have the 740Cs but the project I was using them for was completely designed for me, so I didn't have to use the TSPs for anything. I see that the 740P specs are on the Tang Band site, but no specs for the 740C.

http://www.tb-speaker.com/detail/1208_03/w8-740p.htm
 

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Discussion Starter · #10 ·
Just a question why a push push design? I do understand that you want to reduce cabinet vibrations but why not simply brace you box?
Why build anything other than a single driver in a rectangular box? Main reason is for building one is: ******, I want one...and they're soooo cool! :whistling:

Actually, what I really want is a dual 8 that sounds great; looks great; is unique with both design and build challenges. I don't care anything about knocking plaster off the walls.

I might be wrong but the displacement of those drivers being run from 200 watts is hardly wall shattering power! I am not familiar with that Amp however from experience even with pro audio amps running an amp at two ohm is risky business, also that amp is going to clip trying to run those drivers which are rated at 150 RMS each, i really do think you need to think about budgeting for a bigger anp that you can run at 8ohm rather than 2!
The amp should be here tomorrow. It is a plate amp - is built and designed to run at 2 ohms.

The box the TB's are sitting on is part of a floating shelf I'm building to house all my audio gear.

Warmon -
 

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There are many pro audio amps on the market rated at 2ohms that will not survive driving such loads (even more so when driving bass and this is when the current is often highest) Try it and see how it goes but do not be suprised if it runs very hot. Unlike pro amps it will not have thermal protection, when pared with those two woofers at a 2 ohm load it will be clipping if you want loud bass. If it is simply for some general listening it will be fine but for home theater i think this amp will not provide enough power to driver those subs to their potential. As a general rule it is best to have between 1.5 and 2 time the rated RMS power for each driver. The rated power for the Tang Bang W8-740P is 150 watt RMS therefore you really need anything from 200 to 300 RMS, i really do think it would be better saving for a power amp that can either run each speaker from each channel or be bridged and run the woofers in series for an 8ohm load

Having read your first post you state you are building this for your HT :hissyfit: NOT ENOUGH DISPLACEMENT... Please save for some 10/12/15/18 inch drivers... How are you designing the box? Do you have any graphs for the planned response. I once buil a sub with 8inch drivers and it still serves as a computer sub but in home theater unless you have 4+ you will not get enough impact, another consideration is that it is hard to get bass bellow 25hz with an 8inch driver.

I admit i am making assumptions but in a average sized room and at movie listening levels i think this thing will not be enough :no: Then again i do have a bass adiction :devil:
 

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Discussion Starter · #12 ·
Having read your first post you state you are building this for your HT NOT ENOUGH DISPLACEMENT... Please save for some 10/12/15/18 inch drivers... How are you designing the box? Do you have any graphs for the planned response. I once buil a sub with 8inch drivers and it still serves as a computer sub but in home theater unless you have 4+ you will not get enough impact, another consideration is that it is hard to get bass bellow 25hz with an 8inch driver.
Hello Sam,

I understand your point. What do you think i appropriate for 1500 cubic feet of listening space?...where music and movies are about 50/50, sparsely furnished with wood floors. I am going to model what I think is going to be my final design in Unibox and see how it checks out compared to others. I get conflicting results in WinISD. The drivers want to be in a very small space, however I am going to go towards an EBS -3db type of design - bigger box of roughly 1.5 cft and tune to Fs at 28hz. I am going to run 3 - 3" ports both in and out of the box.

I bought the amp as a new surplus item on ebay. You can read about it here:

http://www.audioreview.com/mfr/eosone/floorstanding-speakers/PRD_120934_1594crx.aspx
http://cgi.ebay.com/225WATT-EOSONE-POLK-1RF0036-1-SUBWOOFER-PLATE-AMP-NEW_W0QQitemZ280142855715QQihZ018QQcategoryZ3275QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

PS: if one won't do the job, I'll build another just like it...:shh:

Warmon -
 

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I was thinking about it and two 8's should give you a similar displacement to a single 12inch which for most people is enough impact. However i still think that for home theater youy really want a response down to 20hz, no matter how you try with an 8 inch it wont happen. Another consideration is that for a vented box you shouldn't really tune to far bellow the stated fs. of the driver. Personally i would try to aim for a tune of roughly 30hz, I will download the parameters of this driver and have a play.

Having thought about it my first sub was an eight and i had a lot of fun designing it and building it. It was tuned to 35hz but it still provided enough bass for movies and music. The only real problem is that in movies you need to watch an 8 because it will KILL itself trying to reproduce 15hz. Would it satisfy me... no but then again if you do not currently have a sub you will notice a significant improvement.

As for the amp i would save and buy a A500 bu behringer which should provide each sub with 170RMS, i really think that plate amp will strugle and clip trying to drive both speakers. Please post some picture.
For music it whould be a good sounding sub, like i said just watch the cones when watching bass heavy music, my 8 goes nuts in U571 :yay: well not yay because one day its going to go BANG :dumbcrazy:
 

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No 8 inch sub should be trying to reproduce 15hz. That's what a sub sonic filter is for. The number one consideration in a proper sub design is the limitations of the driver. A subsonic filters job is to block the frequencies that a driver is not capable of handling. There's nothing wrong with tuning a sub to lower than the Fs. The problem is when you play frequencies lower then the tuning frequency. That's when a driver will "unload" and damage can occur. Raw Acoustics built home subs with this driver. 14 inch external cube tuned with two 2 inch by 16 inch long ports, if memory serves me right. It could handle 150 watts with no problem.
 

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Discussion Starter · #15 ·
Re: Tang Band Quad 8 : Push Push Design

Hi guys,

After modeling my design in what seems like about a zillion times, I have decided to add two more drivers, make it a quad ESB3 setup. There will be 4 subs in a dual push push setup. The box will be roughly 3 cft. One thing I have discovered [and it may just be for these drivers] is that it is a whole lot easier to tune a somewhat bigger box than it is a very small one...:dunno:

Since I will now have to wire the speakers series/parallel to get 4ohm, do you think I should rethink the amp? I'm thinking trying it with the Eosone, but not putting it inside the cabinet so that I can upgrade later on.

On port vent location, does it matter what side they face?..or is it best to have them facing the front?

Warmon -
 

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If you go with two more drivers you will need a more powerful amplifier, Buy a ep1500 and run all four drivers at 1200 watts RMS, you will have more than enough headroom and the amp will drive the speakers to xmax without raising a sweat, I think you can find them in the US for around 300. Should be rocking in no time :bigsmile:
 

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Personally i would have the ports facing forward from the box on the same side of the driver, although it doesnot really matter where the ports are in the box...
 

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Discussion Starter · #20 ·
Hi guys,

These are my graphs from WinISD. Call it the final draft version. I think ESB3 is the way to go [in yellow] - am losing very little in the lower mid bass and gaining quite a bit on the low end. Overall, it looks way better with 4 drivers than 2. I will be using 2" ports cause I have a bunch of 2" ABS on hand - with the goal of keeping port velocity at 6' per second or under. I will run three in the front and three out the back.

Warmon -
 

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