Eminence Lab 12 Subwoofer Project

Great !
Can you post some pictures Ronnie ?

From concept to reality that was pretty quick I would say !
Please post some pics and design of your box.
Regarding power amp, if you are handy with a soldering gun then let me know. I have some ideas.

I will take some pictures this weekend and post.

I went ahead and bought a Pro amp for the Sub this weekend. It's a Tapco J 2500 amp. I was concerned about the fan noise, but it seems to be a non issue.

I have the Sub hooked up through my receiver and overall very pleased with the sound.

I will post pictures and graphs this weekend.

Ronnie

Here are some pics of my subwoofer.





Tapco Amp (bottom left on the rack)




It's a dual front ported 165 litre box tuned at 17 Hz. I constructed the box using 3/4th inch MDF. The eminence Lab 12 driver is being driven by the Tapco Juice 2500 Pro Audio amp in bridged mono mode.


Here are some simulation graphs from WinISD for my Sub:

SPL:


Cone Excursion:


Group Delay:


Port - Air Velocity:


Amplifier Apparent Load power(VA)

[quote="surrealistix"]Here are some pics of my subwoofer.

quote]


Impressive !!. Congrats....and good job. It should be a inspiration for many others...

SUPERB !

Really nice and Quick - surrealistix

Here are some simulation graphs from WinISD for my Sub

Can you tell us some more about how these are obtained ?

I know Zilch on the topic.

Thanks

My first DIY Subwoofer Project:

Functional Goals:

• At the minimum, sound significantly better than my Polk Audio PSW 500 subwoofer in my HT setup
  
• Should sound as good if not better than subwoofers available in 50K to 80K for HT use
  
• Total costs should be under 30K – its too risky to spend more on my first DIY project
  
• A big bonus if the sub integrates well in my stereo setup
  

Design Goal:

• Should sound reasonably flat down to 25 hz (in room)
  
• Group Delay should be kept below 6 to 8 ms above 30 Hz
  
• Port air velocity should be under 17 m/s
  
• It should be able to reach 105 db SPL without exceeding cone excursion limit of the driver
  

Implementation:

The Eminence Lab 12 looked like a really good driver and was available at a reasonable price in India. Other than importing a driver, I didn’t find any other 12 inch driver that would be suitable for a subwoofer in India.

I was very keen on building a sealed sub, but the Lab 12 didn’t seem to lend itself to a sealed design. I spent a lot of time with WinISD and Bassbox pro and read up extensively on forums to finalise on enclosure design which comes close to my design goals.

I finalised on a 163 litre box with two front ports tuned at 17 Hz. The effects of the port seems to kick in below 30 Hz and it didn’t require any boost using parametric eq or Linkwitz Transform.

Given that I didn’t need any active eq with this design really helped, as this is my first project and it certainly helps to keep things simple.

Amplification: I was contemplating getting an O Audio plate amplifier based on recommendations from Ashok on the forum, but finally went with a pro-amp as I didn’t seem to need a cross-over or eq. The Tapco juice 2500 was available for the same price as the O Audio plate amp with 4 times as much power (2500 watts at 4 ohms). I didn’t need any of that power for my current project, but I figured that I may want to run two subwoofers so the pro-amp seemed to be a more future proof choice.

Setup:

HT: I am simply using the LFE from my Denon 3808 receiver going into the Tapco amp (Bridged Mono). I used the Audyssey EQ on the receiver to setup the crossover and levels. The setup was simple and sounds really good.


Stereo: I don’t use the Subwoofer in my Stereo setup as it feels unnecessary. The Usher BE-718 speakers go really deep down in my current setup. Since I made this baby with my very own hands, I have to use it in my Stereo setup anyway (well…occasionally).

Since I use my PC as the front end, I decided to use a software cross-over plug-in on Foobar. My M-Audio sound card can do SPDIF out (bit matched) and LR (Balanced analogue) simultaneously.

So I have the SPDIF out connected to my external DAC for the front speakers. This ensures that I don’t touch the Stereo signal path in anyway by adding the sub. I can switch on the Sub by enabling the crossover plug-in and using LR analog output summed mono feeding into the pro amp. The Foobar crossover plug-in allows all kinds of cross-over tweaking and I have been playing around with these settings.

http://xover.sourceforge.net/


I am reasonably convinced that my Usher BE 718 speakers don’t really need any assistance from the Subwoofer except for may be when I have a party in my house listening to music that needs to shake the floor. I tried the sub with my smaller Usher S 520 speakers and found the two integrated really well.


Overall, I am super happy with my first DIY Sub. It sounds tight, goes deep and can play really loud without breaking a sweat.

Parts and Cost:

I still need to veneer the box, but the cost so far:

• Eminence Lab 12 driver: Rs. 8,500 shipped to Mumbai from Cinetekk Chennai
  
• *Tapco Juice 2500 Pro Amp: Rs. 19,500 from Narain Pro Audio, Lamington Road, Mumbai
  
• 8X4 MDF sheet – Rs. 1400
  
• Carpenter, glue and other misc cost: 1200
  
• Total: Rs. 30,600
  

* I could have gone for the Tapco Juice 1400 or Juice 800 and saved Rs. 7000 to 10,000 bringing the overall cost down significantly.

Hi surrealistix,

Many thanks for the detailed post.

Since I know nothing on Speaker and sub woofer design, I found your poost an informative read.

I have a few questions :

1. The parameters of the Eminence Lab 12 are specified in detail ?

Where can I read these, to get a better understanding of the parameters involved >

2. The Computer screen shots were based on use of the published parameters and a dual vented, 163 litre box ?

3. Are the Box dimensions important ? Can any aspect ratio ( other than a Cube) be used, as long as the Box volume is 163 Litres ?

4. Is the Volume of the Box, Including the woofer inside the box, 163 litres ? ( then the air enclioosed would be less than 163 litres.. ?

5. Any light you can tghrow on the relevance of the Group Delay and Max air velocity specs... Much appreciated.

What are the audible effects ?

6.

I used the Audyssey EQ on the receiver to setup the crossover and levels.

What type of equaliser is this ?

Low pass / high Pass or Graphic Or Parametric ?

Many, Many thanks again.

It is great to know that your DIY effort has paid off so well, I am sure, in no small measure to your detailed reseasrch on the net, before undertaking it.

Great that te Hobby has yielded so much pleasure, without costing an arm and a leg !

Congratulations on a fabulous project! Designing and building a good subwoofer is a huge challenging as I found out some months ago. On top of that tuned port boxes are trickier than sealed boxes.

Overall 9/10. It looks good and the pains you have taken in R&D shows. The best part is that having built it yourself you are well placed for MK-II version. I am sure you will be doing some tweaking.

I have an issue with the wall thickness of your box: Although the bracing is just right, I would have liked a thicker wall. You can still do it by cladding another layer of MDF. Then your total wall thickness will be about 2 inches and that is a good thing for a design that is tuned so low. A thicker wall (and internal bracing) allows a “dead” cabinet.

Take the “knuckle” test. Tap the box sharply with your knuckles. You should hear a muffled “thuck” and nothing else. Somewhat like tapping a granite floor. The box should not contribute its own generated signatures. A good box should be out of the sound equation. Most commercial speaker boxes will fail this “knuckle” test.

Secondly, did you line the internal wall with sound absorbing felt? Many people believe that in a subwoofer it is not important. It is important! I bought audio lining and it cost me about Rs. 1,000. And finally what kind of stuffing you are using? I used sheets of thermal wool that is used in insulating a/c ducts, etc. It is expensive but good. Take care when handling these as the microscopic glass fibers can penetrate human skin and cause irritation.

A dedicated plate amp provides more choices in final integration but as you mention the management is good. It’s always better to have a bigger amp and you have done well to get a monster amp.

However don’t let the above views take away enormity of the achievement. You have just started a fascinating journey and it can only get better.

Hi Amp Nut

I will try to answer your questions to the best of my ability, given that most of what I have learnt scratches the surface and is at best half knowledge.

1. You can download the specs for the Lab 12 from the following link: http://www.parts-express.com/pdf/290-570s.pdf

2. Yes, I punched in the parameters into WinISD. The box is a 163 litres dual vented

3. I beleive the box dimensions are not very important as long as you can fit in the port and maintain 3 inch distance from the side to the port.

4. The box is actually 164.5 litres. I noticed that the volume reduction due to the braces and the driver was not really impacting the design much, for example the SPL graph for a 160 litre box for my design was very similar to the 164 litre box. It would be best to consider the volume reduction of the box due to braces and the driver itself for a ported subwoofer.

5. I read on several forums that the port air velocity should be less than 5% of sound velocity which means you have to keep air velocity under 17 m/s. High air velocity in the port will result in noise. I think a flared port helps in this regard to some extent.

Group delay is the rate of change of phase response in relation to frequency. I don't pretend to understand what that means. I have read that low group delay results in a tighter sound. I read on some forum that a good rule of thumb is to ensure that the group delay in mili-seconds multiplied by frequency should be under 400. So at 30 Hz the group delay should not exceed 13.3 and so on.

A sealed sub would always have lesser group delay as compared to a ported sub. However, when I was trying to design a sealed sub with the Lab 12 on WinISD, I found that using Parametric EQ or LT transform to keep the spl curve flat was resulting in high group delay.

6. I am not sure I understand your question or rather the context of the question about the equaliser.

surrealistix schrieb:

A sealed sub would always have lesser group delay as compared to a ported sub. However, when I was trying to design a sealed sub with the Lab 12 on WinISD, I found that using Parametric EQ or LT transform to keep the spl curve flat was resulting in high group delay.

It is because the LAB 12 driver is suited for a ported box.

There were so many 12 inch drivers available in the US which seemed to work really well in a sealed box. The Lab 12 was all that I could find in India and it simply didn't work well in a sealed box.

Having said that - it worked out really well in a ported configuration.

Hi Aks07

Thank you for your feedback - much appreciated :-)

Yea, I am sure there will be an MK II.

I will try the knuckle test tonight. While doing my research I found an enclosure designed by Dannie Ritchie of GR-Research which used sand in between two walls for a subwoofer, so I figured that the box could be damped later by building an additional wall around it and filling it with sand.

I am not using any stuffing or lining as of now as I was not sure if it's important in a ported sub. The top lid of the subwoofer is not glued as yet, I am using screws to hold it tight temporarily till I have finished tweaking the enclosure.

Is Thermal wool the same as Glasswool? I don't think Glasswool will be a good idea in a ported sub as due to the sound pressure and air movement it will probably start leaking out of the ports and go straight into my lungs! I could use Reckron, but not sure if would help in a subwoofer.

Where can I buy the lining you are talking about?

Here is a pic of the inside of the sub in it's current state:




I will probably have more questions for you as I start tweaking this sub further over the next month or so. I really appreciate your inputs.

That sand filed panel idea is good but sounds a little cumbersome. Do go for it if you have the means and skills. You can also consider making the 2nd layer with granite. But that’s probably an overkill. MDF+MDF sandwiching is most practical. Just ensure the panel are glue absolutely tightyly. You don’t want a “WTF was that resonance??” moment when Battlestar Galactica fires its engine.

That thermal insulation material id different than glass wool and more expensive. It comes in shape and size of a bed mattress. You will need to buy one full “mattress”. You can cut pads and simple insert them into the box. They are not loose and will not clog or fly out of the port. You may ask some of the refrigerator guys about sources. Reckron is pretty useless in a subwoofer.

The lining I m talking about is used in anechoic chambers, recording studios or as damping liners in lab and medical instruments. There are several types depending upon application. The one I used had three layers. The bottom layer was bitumen lined with cotton threads, the middle layer was thickly woven cotton and the top layer was made of a cotton synthetic material. Its about Rs. 450/mt and you will needs about 2.5 meters. However, I would encourage you to try out the carpet material that is used in cars. Today I would prefer this considering the hassles in procuring and preparing the audio felt.

Now that the innards of your box are visible clearly, I would redesign that bracing. The member from rear should brace the front baffle. The rear wall needs two vertical braces about 3” each side of the centerline. These should be about 4” deep and brace the bottom, rear and top panel. And finally I would prefer to have a brace running across and supporting the L, R and Top panels. Ditto for bottom taking care of the port tubes. Please note you may not need such rigid bracing if you are going for a sandwich design. In fact simply sandwiching would be an easier option. But as of now I feel your box is not rigid enough.

Have you flared the port mouth? That will tame the exit velocity somewhat.

I tried the knuckle test. The front side of the sub where I have two walls sandwiched sounds more dead as compared to the other walls.

So, I guess it will help to have the sub double boxed. I wanted to go with a Flared port, but I didn't know where to purchase a flared PVC pipe. In any case, I don't hear any noise from the port, so not sure if its required.

The carpet material for inner lining sounds simply enought, so will do that for sure.

I will go check with the refrigerator guys. Do you think I could seal the Glasswoold Rigid Fibre Boards into a thin cloth and use that instead?

surrealistix schrieb:

Do you think I could seal the Glasswoold Rigid Fibre Boards into a thin cloth and use that instead?

Why not? You are DIYing my friend ! Just ensure that the ports are not blocked. Try with 70% stuffing and add/remove as you tweak.

Sandwiching is the way to go.

hello
I am new to this forum and was searching the web for Lab12 projects and found this project
only the 164 liters is to big for my room, but it looks great
this week I received a Lab12 woofer
I am using it in a 95 liter cabinet tuned to 22 hz
the subamp is a Reckhorn A401 and the subwoofer sound great
already after a few days
the cabinet I use is from a BK Monolith, a subwoofer company from the UK
this week I will tune the subwoofer with the internal damping materials
I will also try to post some pictures

Ralf

Please do post pictures and let us know about how it sounds.

A smaller cabinet would be ideal.

HI surrealistix,

I am new to the forum. Your Sub rocks I was impressed by the desing and look. I need to clone you sub. Can you let me know the construction details? I am ordering the SUB this week.

Thanks in Advance...

Sreekanth - I will be happy to help. Let me know what information you need other than what I have already posted. Be sure to incorporate suggestions from Aks07 about thicker MDF and lining etc.

I haven't made any changes to my sub from the initial build as yet. I recently bought a Behringer mic and a mic preamp to do some tests before I make any changes to see a before and after change.

Now that I have a measurement system in place, my next project is to find the best location for the sub in the room, and ensure a proper frequency and time alignment with the front speakers.

Hi Surrealistix,
Thanks for your replay. I am looking for help on cutting dimensions of MDF board to build this enclosure of 164lts. I need to hire a carpenter for this and I need to provide him with this information as he doesn't have an experience in building enclosures. Also the port diameter to be cut.

I am also incorporating suggestions from Aks07. I am using 1.5 inch MDF board. The damping materiel I am planning to use is a glass wool mattress. We get glass wool in 2 types as a mattress(Yellow color) and loose form(white in color). I think Aks07 is referring to the first one.

I was also impressed with his SB12 sub-woofer project (http://www.hifi-forum.de/viewthread-168-29.html). Since the drive was not available any more, I move on to the Lab12 which is easily available.

I think the lining material may be eliminated as we are using glass wool, any suggestion?

Since you have measuring instrument can you share any changes or update made so that I can implement the same.

I am also considering to build floor standing speaker for my next project. I am checking for good drivers availability in India for this project. Getting good drivers is a biggest challenge I am facing currently. Do you have any suggestions?

Thanks,
Sreekanth

You may want to check out the norge website.

they have started selling wavecor drivers. I believe ready made cabinets may also be available.

manek.

Wow thats a great project!!
I thought I am the only one using the LAB12 in my HT^^

In my opinion the LAB12 is the perfect balance between Hifi and PA.
Some impressions on my Sub:

This Sub was developed by a friend of mine with the help of professionals.
It's in a ~115 lt sealed box with two passive membrane.

And i kicks ass

Some information:
Main: LAB12

Passive Membrane: Nova (It's a pity that these passive membrane are not longer produced, otherwise i'd build a second woofer^^)

Amp: A active modul by Magnat, 300 watts on 6 ohm (it is taken from this sub: http://www.hifi-regl...32c04e86d52eb45726db )

Some pictures:





Back with the passive membrane:



The Amp:





One latest version shot of the front:



regards hendrik

Hi Hendrik,
What are those floorstanders at the back ?
Which make and model ?