Help with seal tempest

[mardelgo]

Hi.
I build a 5cuf seal tempest and I having problems. At first I use a 500 watts oaudio amp but I was having distortion on loud moments on movies so I thought it was the amp clipping. So I change the amp for a berinhger EP4000 and use this amp in bridge mode. But it still distorts on loud moments and the amp is not clipping, so I guess I am making the tempest distorts ( bottom out) . It this possible even with the oaudio? Is a seal desing is that inefficient that is it that easy to distort? I find estrange that the oaudio was able to bottom out this driver so I am confuse. The box is fill around 60% with poliester fiber and mineral wool, I was thinking of adding more to see if that helps. Also, the woofer is set in a large room but the woofer bottom out at least 6db lower than the normal listening levels and it is set it 1db lower than the rest of the speakers) Any help will be appreciated.

http://img148.imageshack.us/img148/7897/tempestn.jpg
http://img10.imageshack.us/img10/8739/insidevl.jpg

 

[annunaki]

I would first check your enclosure (which looks great by the way) to ensure it is air tight. If you have leaks, this can happen as the air in the enclosure will no longer act like a spring.

Assuming you have the tempest X2 5.0ft^3 is the right size for a sealed enclosure. I would try reducing the amount of stuffing that you have used taking it down to say just 25%.

The next step would be to ensure that you are not running additional EQ below 30hz with the amount of power you are running.

This driver should not be distorting if you have properly set up the gain structure on your amplifier.

You may want to try adding a notch filter at say 20 hz or so reducing the output by around -3db with a net "q" of 1.0. This may help out with your "bottoming" issue as well. With 1200 watts rms the driver will begin to exceed xmax at 31.8hz without using the filter I have suggested. Using the filter above xmax will not be exceeded until 16.2hz.

 

[GranteedEV]

I would first check your enclosure (which looks great by the way) to ensure it is air tight.

How do you check this? At around -8db on the receiver, Inception caused my maelstrom to bottom out so I want to know if that's just the limitation of the driver or a problem with my box.

I was also getting red clip lights on my amplifier (Tapco J2500). Was it just the scene(s)?

 

[annunaki]

When the driver is loaded and one pushes gently but continuously on the cone for a reasonable amount of time (5 seconds or so) the woofer cone should only move slightly inward but also still feel stiff. When released it should move very quickly to the rest position.

If when pushing consistently, the cone keeps moving inward, and when released slowly moves back to rest, the enclosure has a leak.

I recently just watched Inception and there is some very deep passages at a couple of spots. I would say some of it was in the mid teens at a very high level. My entire room and all of its occupants shook during those points with my 12W7.

You may want to revisit your gain structure on your amplifier if you are getting clipping. If the clip lights were only flickering lightly, you are probably still fine. It would depend however on what the manufacturer deemed as the clipping point.

 

[90gstman]

When you say it's distorting, what type of sound are you hearing? The reason I am asking is the sound of a driver bottoming usualy sounds like a thunk or a clunck. If the driver beyond its normal travel range, but not bottoming you get a lot of doubling ( 2nd, 3rd, 4th, etc distortion). That is, if a 20hz note is played you end up hearing it as a 40hz, 80hz note instead. If the amp is runing out of power you kinda get a sharp or harsh sound.

The box itself can be making the distortion too. What material is it made of? If the walls are flexing or vibrating you will hear it. The surface area of the box is a lot greater than the driver, so if its moving only a fraction of a mm, your going to hear it. If you have a disk with test tones on it play them one at a time and go over to the box and feel the walls of it. Move your hand from the corners to the center and see if you can feel it vibrating at certain tones. If this is the case, we can figure out a way to save the box.

Let us know.

 

[j_garcia]

I am kind of surprised because I think it would be pretty difficult, if not nearly impossible to bottom out a Tempest in a sealed enclosure. I could push my former Tempest (sonotube, vented, lowQ) hard and never once bottomed it. What you are hearing is not bottoming for sure.

 

[mardelgo]

Thanks everyone for the tips. I starting to believe that I have a small air leak because I also find estrange that the tempest distorts that quickly. It must be a really small leak because distortion occurs in extended bass sequence and it really sounds as bottom out. When I press the driver for 5sec it goes back up normally, but if I press it for 20 or more sec, I think it stays a little lower and returns slowly to his normal position. I think the leak may be between the driver and the enclosure, I going to change the screws to a bigger ones because with the ones that I am using now I am not able to completely press the foam that is between the driver and the enclosure, there is no gap, but the gasket foam is like 3mm thick but I can see parts between the driver and enclosure that the foam is not completely compress still is like 1.5mm thick, this may be the problem. I let you know how it goes. Thanks

 

[ronmexico]

How are your voice coils wired? In series I presume?

I experienced a very similar issue with mine... I accidentially (tried to be too clever ) wired up my voice coils in parallel.... which presents a 1 ohm load to my 500 watt plate amp..... though the plate amp kept up for a while ultimately it completely fried the output stage. The tempest X2 has 2 dual 2 ohm each voice coils... so in parallel it is 1 ohm.... in series is 4 ohm (which is a "typical" load for home amps).

I had noticed it was "bottoming out" or clipping with high SPL (kind of a annoying thumping sound at times).... and my clipping light would flicker on the amp... unfortuantely I didn't figure it out until it was too late. Amp is now in the shop

 

[mardelgo]

Hi. I find what the problem was. It was a manufacture defect, the spider was lose in some parts, I believed there wasn't enough glue. I re-glue it my self,(it was to expensive to send it back) and it is working fine. The only problem is that the oaudio amp (500watts) it is not enough and it clips sometimes. It is possible to add a round port to convert it the box to a bass reflect design to gain some db? The box is around 5cf (20" x 30"). And if so, what length and diameter of port I need?. Thanks again

<img src="http://img96.imageshack.us/img96/3066/1sttempestproblem1.jpg"
<img src="http://img715.imageshack.us/img715/8457/1sttempestproblem2.jpg"
<img src="http://img135.imageshack.us/img135/6742/subbox.jpg"

 

[mardelgo]

I made two ports with 3in pvc to make a test, and it is a big improvement. I using the 16hz subsonic filter because it is flatter than the 20hz filter I guess because the way the oaudio apply the filters.( I have a peak of around 4db between 20 and 25hz on the 20hz subsonic filter) I think I gain around 6db overall, I can hear some port noise at very loud moments if I am near the subwoofer (3ft) but it is not detectable or very low at the listening position (12ft).

 

[highfigh]

Hi.
I build a 5cuf seal tempest and I having problems. At first I use a 500 watts oaudio amp but I was having distortion on loud moments on movies so I thought it was the amp clipping. So I change the amp for a berinhger EP4000 and use this amp in bridge mode. But it still distorts on loud moments and the amp is not clipping, so I guess I am making the tempest distorts ( bottom out) . It this possible even with the oaudio? Is a seal desing is that inefficient that is it that easy to distort? I find estrange that the oaudio was able to bottom out this driver so I am confuse. The box is fill around 60% with poliester fiber and mineral wool, I was thinking of adding more to see if that helps. Also, the woofer is set in a large room but the woofer bottom out at least 6db lower than the normal listening levels and it is set it 1db lower than the rest of the speakers) Any help will be appreciated.

http://img148.imageshack.us/img148/7897/tempestn.jpg
http://img10.imageshack.us/img10/8739/insidevl.jpg

5 ft³ is a big box- are you absolutely sure the volume is correct? If it's way too large, the box won't do much damping.