Should I tamper with my sub?...

[Hi Ho]

I built my DIY subwoofer last April. I used an Ascendant Audio Atlas 12" driver and a 250w Parts*Express plate amp. I followed the advice given by people at AVS Forums and used some proven plans so I did not mess up my first DIY project. I was so impressed with it that I have not touched it since. As you can see, I never got around to doing veneer either.

Anyway, while I am extremely happy with it, I can't help but wonder "what if?" Following the advice given to me, I tuned it to 18hz... or was it 16hz... frankly I can no longer remember and I cannot find the threads regarding my project (all of my threads at AVS about DIY subs have mysteriously dissapeared while other's have remained).

Another thing I was told to do was to disable the bass boost function in the amp. This involved replacing two transistors with different ones, an annoying process that could have been easily completed with a switch. In fact, I should have wired in a switch when I disabled the bass boost.

Now I wonder what would have been different if I had tuned it to a different frequency or left the bass boost enabled. I never used the amp with the bass boost enabled.

The sub doesn't have a lot of output above about 80hz. This would be fine with me except for the fact that my receiver's crossover will not go below 100hz. Playing a 16hz test tone literally shakes the house. I have no SPL meter so these "measurements" are all I have.

Should I tamper with it? Could I do any good? Any and all opinions are welcome.

 

[Dryseals]

Thats the problem with DIY, once you are done, there is nothing to play with. I think I would have some fun and do a little fooling around, as long as you can put it back, what the problem. I'm currently building three systems for the house, maybe four. This way I can experiment from one to another and with multiple systems.

PS, I like the shop, I noticed the hose for the dust collector. I'm running a Sears unit right now and it seems to pull fine. I need to add a jointer and it will be further away from the unit than any other tool. What collector are you using?

 

[Hi Ho]

It's a Grizzly dust collecter. It works very well. THIS one looks like the closest match.

It's really my dad's shop. It is full of nice tools though. He buys Millwaukee, Bosch, certain Craftsman, and Makita. That table saw is from 1933 and still looks/works like new. I never would have guessed.

If/when I have my own shop I will certainly keep it in much cleaner condition. I will be using the same kinds of tools too. Good tools make a difference.

About the sub, I guess the only thing I could really do, that I could reverse, is enable the bass boost in the amp. That is a hassle though. If I cut the flare port to adjust the tuning I would not be able to put that back.

Maybe it's best to leave it the way it is and maybe put some nice veneer on it.

When I have my own place I plan to build a system or two, or three. I'm looking forward to having a dedicated theater room and being able to build some really nice speakers with Seas drivers and a sub with dual Ascendant Audio Havoc 18's.

 

[annunaki]

The sub looks really nice. What is the ft^3 of the enclosure? What is the length of the port and it's diameter? I can tell you what frequency it is tuned to.

Your bracing looks great, though, next time, you could probably cut out even more mdf to lessen it's displacement.

Did you staple the panels after gluing them? I did not see any screws, unless, you filled them already?

 

[Hi Ho]

The inside is about 4.5ft^3 and the port is at full lengh (18in I believe).

I was following plans and made the braces accordingly. One thing is for sure, this cabinet does not resonate.

I used biscuts and wood glue for everything except the top and bottom panels. For those I used screws and polyurathane glue. There is no chance of this thing ever separating.

 

[annunaki]

Assuming that is a 4" port you are tuned to 18hz I believe. I bet that sounds nice. Those Atlas drivers use XBL^2 don't they?

 

[Hi Ho]

Yep, they use XBL^2. It is a 4" port. It does sound nice, very nice. It will really shake the house.

 

[annunaki]

How linear is the frequency response? Is there a graph? I would assume there is if it was built from plans or a kit. It must play quite deep being tuned that low?

 

[Hi Ho]

I finally found the original thread I was looking for at AVS HERE it is. The plans I followed are HERE. I built the 142 L box but I changed it to front firing. I don't have any graphs. I don't have a sound meter and, while I have attempted to use TrueRTA, I have not been successful in getting any results.

All I know is that I get strong output at 18hz, a little less at 16hz, and a steep drop after that. At the upper end, I'm guessing it rolls off, or has a dip, at around 85hz. The problem with this is that, with my current receiver, I cannot set the crossover below 100hz. I have been living with that response hole but I'm really looking into upgrading to a Yamaha 2500 or 2600.

 

[WmAx]

All I know is that I get strong output at 18hz, a little less at 16hz, and a steep drop after that. At the upper end, I'm guessing it rolls off, or has a dip, at around 85hz. The problem with this is that, with my current receiver, I cannot set the crossover below 100hz. I have been living with that response hole but I'm really looking into upgrading to a Yamaha 2500 or 2600.

Because of your tendency to do unique things to get better sound quality, consider going a route that you can have a seperate pre-amp and amplifiers, so that you can insert the proper signal processors between the two to get optimal results. The built in crossovers and equalizer systems in recievers seem to be pretty limited in what they can do, from what I can tell, overall.

-Chris

 

[annunaki]

I finally found the original thread I was looking for at AVS HERE it is. The plans I followed are HERE. I built the 142 L box but I changed it to front firing. I don't have any graphs. I don't have a sound meter and, while I have attempted to use TrueRTA, I have not been successful in getting any results.

All I know is that I get strong output at 18hz, a little less at 16hz, and a steep drop after that. At the upper end, I'm guessing it rolls off, or has a dip, at around 85hz. The problem with this is that, with my current receiver, I cannot set the crossover below 100hz. I have been living with that response hole but I'm really looking into upgrading to a Yamaha 2500 or 2600.

A receiver with more flexible bass management capabilities would be much to your benefit.

 

[crippledchicken]

Assuming that is a 4" port you are tuned to 18hz I believe. I bet that sounds nice. Those Atlas drivers use XBL^2 don't they?

hi there, i'm new to the forum and was just wondering if you happen to have the new corrected T/S Paramaters for the Atlas 12 since the originals, were determined to be off? i'm wanting to build a new vented enclosure for my Atlas 12 and would like to use the new corrected Paramaters if available. i can't even find the originals anywhere now? thanks, crippledchicken

 

[Hi Ho]

I never heard anything about incorrect T/S parameters. You could try calling Ascendant Audio. They would probably be able to tell you.

 

[crippledchicken]

I never heard anything about incorrect T/S parameters. You could try calling Ascendant Audio. They would probably be able to tell you.

here is one of the posts on the subject of the paramaters problems also, going from low Q setting, to mid, to high they had the QES, listed as changing when it's the QMS, which changes and the QES, should remain the same. another complaint of the various issues which were never explained is, Repost of Atlas 15 Le issues

--------------------------------------------------------------------------------

As requested, here is a repost of this test.

I just measured Atlas 15.
Tool: Philips PM6303A Automatic RCL meter
Frequency: 1kHz
Spec Le: 0.86mH
Measured: 1.86mH
With sense coil shorted: 360mH

Atlas 12 has been independently measured at 2.45mH. This is between 2-3x nominal. thanks, just has me confused on how to model my enclosure

 

[annunaki]

hi there, i'm new to the forum and was just wondering if you happen to have the new corrected T/S Paramaters for the Atlas 12 since the originals, were determined to be off? i'm wanting to build a new vented enclosure for my Atlas 12 and would like to use the new corrected Paramaters if available. i can't even find the originals anywhere now? thanks, crippledchicken

Welcome to the forums!

I am not the most familiar with that driver. I have heard many good things about it though. Like previously stated, I would check with the manufacturer for the most up to date specifications. The driver's specifications have no influence on the tuning of the enclosure, only on how it would perform in said enclosure.

 

[crippledchicken]

hi there, seems like a nice forum! yeah, i have the same exact enclosure design as HI HO with same port length also. the amp i have right now is a little small at 150 watts rms so i plan on getting a RYTHMIK AUDIO 350 SE later on but, ive modded this amp to some extent and it seems to do a pretty good job plus, i have a small room. i'm running on mid Q setting since i listen to mostly music. i've wired mine for 6 ohm configuration once and it seemed like it would be excelent for HT set that way the low bass was really strong on movie tracks with the extra motor strength from the second coil. cheers, crippledchicken

 

[annunaki]

hi there, seems like a nice forum! yeah, i have the same exact enclosure design as HI HO with same port length also. the amp i have right now is a little small at 150 watts rms so i plan on getting a RYTHMIK AUDIO 350 SE later on but, ive modded this amp to some extent and it seems to do a pretty good job plus, i have a small room. i'm running on mid Q setting since i listen to mostly music. i've wired mine for 6 ohm configuration once and it seemed like it would be excelent for HT set that way the low bass was really strong on movie tracks with the extra motor strength from the second coil. cheers, crippledchicken

You are using both coils at all times correct?!

 

[crippledchicken]

hi annunaki, right now i'm just running the 4 ohm coil with a 10 watt 1.5 ohm power resistor accross the gold 2 ohm coil for the mid Q setting as it seems to sound better for music in my setup of 2 channel sound using an Adcom GFP 565 preamp along with a 2 channel onkyo 100 w/p/c power amp feeding speaker level out to the 150 watt plate amp high level inputs. if i were to listen to mostly HT, i would run both coils in series at all times, as it really adds to the deep rumbling, shaking sound effects of HT in this particular vented enclosure. cheers!

 

[Hi Ho]

I have mine set to the low QTS setting with a wire shorting the two terminals, as recommended by Ascendant Audio. I haven't tried any of the other settings.

 

[crippledchicken]

if i remember right, mine has more output wired 6 ohm in series and Chad said the paramaters are almost identical with 6 ohm, as the low Q setting. mine sure sounds better, and stronger like that than the low Q setting. i guess partly due to the increased BL motor strength. might be worth checking out to see if you like it or not. best reguards!