Noob Tempest Questions

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This is my first attempt at building a home sub. I've built a few for my car, but nothing too complex. I've been doing quite a bit of reading and I decided that i wanted to use an adire tempest based on price(i'm in college and don't have much cash) and performance. I still have a few questions though(if they've already been asked, I apoligize as I couldn't find what I was looking for).
Where can I order a tempest from? Every site that carries them seems to be sold out.
I am looking at building the low q sealed or adire vented enclosure from the adire website. Which would be more suited to mostly ht use, or is there a better design without taking up more space?
Also, I've heard that it's better not to brace it so the enclosure so that it gets divided into equal sections. What's the best way to do it with the adire plans?
I've looked at a few amplifiers but don't really know which one to choose. I'm looking at the 250w from MCM electronics, PE, or Rythmik. I might possibly spend a little extra and get the 350w from Rythmik if it would be worth it(I'd like to spend as little as possible but still get the best bang for my buck). Which would you choose?
That's all for now. Thanks in advance.

Josh

PS Right now my system consists of a yamaha htr-5760 and fluance sx-htb speaker package. I'm in a small dorm room now, but I want a sub that acts well in a larger room once I move out(i'd like it to be flat to 25 anechoic). I might add a BFB to help out, but not right away.
 
You can find a list of suppliers on the Adire website. The Tempests are available from www.creativesound.ca but they dont have many left. There will apparently be new stock in Feb.

The best solution for the box is to copy one of the Adire plans. They are tried and true and fairly easy to make.

I built the EBS alignment with 250w and that is plenty. I think I am excursion limited in this design.
 
Just order factory direct from adire. to my area code it is $16 S&H but i found a dealer in tennese that iwll ship it for free so i bought mine there. but $16 is a small price to pay for this amazing woofer.

As far as low bass extension goes. Ported would be your best option. The tempest has a resonant frequincy of around 18Hz. You dont need to go much lower do you? Play around in WinISD or, like you said, just use one of adires proven designs.
 
Ported, for sure. As said creativesound or adire(direct) can both hook you up with a tempest, but there are other dealerships on the adire website, so youcould always find one close to you. If you have the space, you can make a BIG enclosure(260Lish) and tune LOW (13hz ish) and that will match room gain pretty well so youll be flat way into infrasound. IMO i need bass down to 16hz, more movies than you think have infrasonic bass material*.


*some examples are
Finding nemo: whale scene
BHD: chopper blades beating air scene (BIG lump at 5hz)
LOTR ROTK: sauron ring drop, elephant collision.

I believe there is a thread on HTF that has spectrum analysis on many movie scenes.
 
Yes that is true. if you are a big movie man very low tuning feels great when something explodes or a car engine is running. the movie i hate the most, 2fast2furious has alot of Subbass frequincies. All of the explosions and car exausts. when your couch is rocking like you are in the car, ahh thats a true movie experence.
 
Thanks for all of the replys. I've checked about all of the suppliers on the adire website and i think only 1 online store still had them in stock and they were the only ones not giving free shipping. If that's all thats left, i'll just have to pay for shipping but if you know of a place with them in stock and have free shipping I'd like to know. I was thinking I wanted to go ported, but wanted to be sure. Also, I saw that parts express had some 3" flared ports on sale(269-932). Would they be a suitable replacement for the adire ports? Finally, is there much of a difference between the MCM, Rythmik or PE amps? The rythmik seems to be the best, but I know there are some things that they don't tell you. Thanks.
Josh
 
Anybody? Still wondering which plate amp is the best. Also, will the PE ports work for the 3rd vented box design on the adire tempest recommended? Box specs say an 11" long tube with the adire flares. It's a 1 piece flared tube with an 11 1/2" length. Would they be the same or real close? How much would it change the tuning? Thanks.

Josh

PS I ordered a sub, but i don't know if they will be able to ship one or not. Any other sites that carry them for under 160 shipped would be appreciated.
 
Do you have a link to the MCM and PE amps? I'm familar with what rythmik has and their amps are pretty good. On the nonsevo amps you can get a LT add on, there are numberous features such as continuous phase adjustment, 107db+ S/N, gold plated connectors, thermal protection, adjustable crossover, you name it. I dont know what those other guys have to offer, but most likely not nearly as many features
 
Here's the link to the PE amp: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794
and the MCM amp: http://mcm.newark.com/NewarkWebCommerce/mcm/en_US/endecaSearch/partDetail.jsp?SKU=50-6281A&N=4
For the MCM amp details, you have to search for it and click on tech info. I was leaning toward the Rythmik amp based on price and my first impression but I haven't ordered it yet. If I do get the rythmik amp, what would be the rumble filter setting I need for a 214L box tuned to 15.4hz? thanks.
Josh
 
The amps are very similar, except you can adjust the rumble filter on the rythmik and it also has higher S/N ratio. The PE and MCM amps also do not advertise dampening factor, which rythmik does indicating that their amps probably perform well in that area, while the others might not
 
Ranthum said:
Here's the link to the PE amp: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794
and the MCM amp: http://mcm.newark.com/NewarkWebCommerce/mcm/en_US/endecaSearch/partDetail.jsp?SKU=50-6281A&N=4
For the MCM amp details, you have to search for it and click on tech info. I was leaning toward the Rythmik amp based on price and my first impression but I haven't ordered it yet. If I do get the rythmik amp, what would be the rumble filter setting I need for a 214L box tuned to 15.4hz? thanks.
Josh

Our rule of thumb: set the rumble filter to same as the box tuning frequency. You don't really have a choice here. Set the rumble filter too high, roll off the bass too early; set the rumble filter too low, not enough protection for the driver. The only thing you can play with is Q value. Now, the real concern I have is the box size and the efficiency that come with it. To give you a rough idea, the box you have 214L can be up to 4 times more efficient (in terms of power) than a 100L box (at the tuning frequency and below). That means if you are using 350WRMS amp, the person with 100L box will need 350Wx4=1400W RMS amp. Above tuning frequency times 1.4, the efficiency is limited by the driver. With such a high efficiency, 350WRMS is definitely too much. I would recommend you to scale down the power and pick and amp that is flexible in setting up rumble filter. Or use one amp to drive 2 boxes.

Brian Ding
Rythmik Audio
 
Looking at WinISD specs it seems that 350watts would be just about perfect. Max power of the tempest is at 750watts. WinISD's max power simulation shows a dip centered at about 25hz that has a local minimum of 320watts. 350watts would probably be nice for a little extra headroom there. How much power do you suggest Brian?
 
I was thinking of getting the 250 watt model. That shouldn't be too much power with a tempest should it? Do you have a phone number that i could reach you or somebody else at rythmik to discuss/order an amp? I want to make sure i'm getting the right amp with the right settings to get the most of my sub while still protecting it.
Josh
 
Ranthum said:
I was thinking of getting the 250 watt model. That shouldn't be too much power with a tempest should it? Do you have a phone number that i could reach you or somebody else at rythmik to discuss/order an amp? I want to make sure i'm getting the right amp with the right settings to get the most of my sub while still protecting it.
Josh

Josh,

You can give me a call at (714)612-2590. 250WRMS will be more reasonable. Even that you need to resist the temptation of cranking up the volume. In the previous post, I mainly just wanted to caution you the potential problem. The numbers that I quote you were more of a guideline. Now, you would like to tune it to 15hz which is quite low. If you compare a simulation of the same box tuned to 20hz, you may find the excursion requirement of your enclosure is larger. If you don't push the amp into clipping, the rumble filter will be very effective. However, when the amp clips, the output from the amp contains spectral components that are not in the input signal. These newly introduced components are hard to predict. But if they happen to have components at the frequency that the enclosure is most susceptible to over-excursion, it can easily overload the driver. In short, a rumble filter protects the driver from the signal that you feed the amp, it does not protect you from the clipped waveform created from amp when it is into clipping.

Brian Ding
Rythmik Audio
 
BassAwdyO said:
Looking at WinISD specs it seems that 350watts would be just about perfect. Max power of the tempest is at 750watts. WinISD's max power simulation shows a dip centered at about 25hz that has a local minimum of 320watts. 350watts would probably be nice for a little extra headroom there. How much power do you suggest Brian?

Mike,

I would recommend no more than 250WRMS output. Another thing I would like to point out is over-excursion has little to do with power in vented box. It is kind of hard to read from simulation. First, if the simulation result does not include the effect of rumble filter, you will see tremedous excursion below box tuning frequency. So that does not tell you the acutal excursion when one adds a rumble filter. On the other hand, if the simulation does include the effect of filter, it is hard to see the weak spot of the driver when the amp is overloaded. Plus there are some drivers that are well behaved when the voice coil is over driven to out of the gap and others that a small overload can cause the voice coil "slide" to reach the suspension limit. It is a matter of spider design.

Brian Ding
Rythmik Audio
 
Hi Brian, I just did a EBS Shiva box (142,5 liters tuned to 18,4 Hz) with your 250 W RMS amplifier. You have your rumble filter set at 12 Hz. As I can see, I will run in overexcursion under 16 Hz. You think it would be worth it to modify your stock rumble filter? You know, I don't want to break something and lose the warranty on your amplifier but I don't want to break the Shiva! ;)

If I tune the rumble filter at 18 Hz to protect the driver, I lose 2 dB at 20 Hz which is not acceptable, since I want to beat a SVS PB10-ISD in linearity, distortion and loudness.
 
simon5 said:
Hi Brian, I just did a EBS Shiva box (142,5 liters tuned to 18,4 Hz) with your 250 W RMS amplifier. You have your rumble filter set at 12 Hz. As I can see, I will run in overexcursion under 16 Hz. You think it would be worth it to modify your stock rumble filter? You know, I don't want to break something and lose the warranty on your amplifier but I don't want to break the Shiva! ;)

If I tune the rumble filter at 18 Hz to protect the driver, I lose 2 dB at 20 Hz which is not acceptable, since I want to beat a SVS PB10-ISD in linearity, distortion and loudness.

Keep in mind, a rumble filter protects the driver from signals below box tuning frequency and it does not have any effect on a clipped output signal from power amp. So the most important thing is keep the volume at reasonable level so that the amp will not be driven too much into clipping (slight clipping is ok). For a movie track, the sound engineers are supposed to filter out the signals below 20hz (or something a bit lower than that), not for our benefits, but for the speakers in movie theaters. Those speakers are most likely ported. Heavy signal below 20hz can overload them. That is one reason that some people are ok with their vented box even without a rumble filter. But you cannot count on that for all movies because some of them do not follow this guideline. As for the rumble filter, a Q value of 1.0 is in general good. It has a small boost of 1db in the passband, and at the same time have a sharp roll-off below corner frequency. The lower the Q, the more gradual the roll-off. So it may be worthwhile to put a filter with Q=1.0 or 0.9 if you like, that just starts to roll off at 20hz. So there is no attenuation at 20hz (or above). It is definitely doable.

Brian Ding
Rythmik Audio
 
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