After completing my Adire recommended mid Q design sealed enclosure for the Tempest, I'm not real happy with it. It seems to have enough output, but the sound is quite boomy. I haven't figured out if the PE 250 watt plate amp I'm using is the culprit, the enclosure, or a combination of the two. I have not heard good things about these plate amps in terms of their quality. I've been told they have a dampening factor of only 40-50. Anything less than 100 is terrible, and most good rack amps have a DF of at least 200. I contacted PE's tech dept to ask them for the DF on their plate amps. They said the man's don't provide that info. My guess is if the numbers were good, they'd provide them.
I like tight, punchy bass and this enclosure doesn't provide that. I think maybe what I should be looking at is building the high Q enclosure, with a better quality, more powerful rack amp of about 700-800 watts with a DF of >200. What do you think? Will this get me tight punchy bass?
I like tight, punchy bass and this enclosure doesn't provide that. I think maybe what I should be looking at is building the high Q enclosure, with a better quality, more powerful rack amp of about 700-800 watts with a DF of >200. What do you think? Will this get me tight punchy bass?
Hello grampi
I'm sorry to hear the project didn't turn out well. I've
had my share of disappointing designs myself.
I'm just curious if you;
1. Have the box damped?
2. Have the Crossover Setting to high?
3. Have the Sub in a corner?
Although I've never used nor heard a Tempest,
these questionare's basically applies to any
powered sub.
I'm sorry to hear the project didn't turn out well. I've
had my share of disappointing designs myself.
I'm just curious if you;
1. Have the box damped?
2. Have the Crossover Setting to high?
3. Have the Sub in a corner?
Although I've never used nor heard a Tempest,
these questionare's basically applies to any
powered sub.
It's interesting you chose the MidQ design after asking me.
You may be interested in this thread too.
Thread on overdamped subs
This thread should put your mind at ease about damping factor.
http://www.diyaudio.com/forums/showthread.php?threadid=22107&highlight=
The only thing I really know about damping factor is that in competently designed amps, even inexpensve ones, it really is not too important.
http://www.diyaudio.com/forums/showthread.php?threadid=22107&highlight=
The only thing I really know about damping factor is that in competently designed amps, even inexpensve ones, it really is not too important.
omnifex
If you mean did I add polyfill to the box, yes I did. 40 oz.
I've set the crossover point from as low as it goes to as high as it goes. Doesn't seem to make much difference with the boominess.
The sub is located along the back wall of our living room about 6 feet from a corner.
Timn8ter
The reason I decided to go wth the mid Q design is because I'm only using a 250 watt amp and I thought the high Q design would choke off the sub. Now if I was using an amp that delivers close to the Tempest's max power (750 watts), then I'd go with the high Q design.
If you mean did I add polyfill to the box, yes I did. 40 oz.
I've set the crossover point from as low as it goes to as high as it goes. Doesn't seem to make much difference with the boominess.
The sub is located along the back wall of our living room about 6 feet from a corner.
Timn8ter
The reason I decided to go wth the mid Q design is because I'm only using a 250 watt amp and I thought the high Q design would choke off the sub. Now if I was using an amp that delivers close to the Tempest's max power (750 watts), then I'd go with the high Q design.
PEQ is the answer.
Sounds like room modes to me, I doubt there is anything wrong with your sub, when you start pressurizing a room with a some serious bass like the Tempest can put out there is always going to be room problems. Try a BFD or some quality Digital PEQ, it will make everything sound better regardless of the situation. Do you have a SPL meter?
Sounds like room modes to me, I doubt there is anything wrong with your sub, when you start pressurizing a room with a some serious bass like the Tempest can put out there is always going to be room problems. Try a BFD or some quality Digital PEQ, it will make everything sound better regardless of the situation. Do you have a SPL meter?
grampi said:
I have a Tempest in a box that falls in between the midQ and lowQ Adire factory alignments, about 165L, with a 250W plate amp. Mine is a bit boomy, but still pretty good for music. Mine fires down onto carpet. The 1st thing I would recommend is to play around with the surface you are firing against. Try carpet; put spacers under the 4" feet, etc.
If you think the sound is boomy and you want it tighter, do not make a smaller box/high-Q design! For a tighter sound you must lower the Q, which means a bigger box.
Increasing box size would also make it more efficient which would be good with your limited amplifier power. And that damping factor 40-50 is fine. You would need a really low damping factor (like 5 or less) to really make things boomy.
Also, as others have wisely said, try experimenting with placement.
Increasing box size would also make it more efficient which would be good with your limited amplifier power. And that damping factor 40-50 is fine. You would need a really low damping factor (like 5 or less) to really make things boomy.
Also, as others have wisely said, try experimenting with placement.
My first guesses/thoughts are:
- integration with main speakers isn't working quite right: too big a peak or dip, or too different quality even. Are the main speakers sealed or ported? Might be a consideration.
- room modes are killing the subjective speed, as said already
- you simply aren't used to the subjective change of pace when hearing more extended bass output. Usually fast, tight, punchy bass just means cutting off anything below about 60hz, so if you've not thought about that effect, bear it in mind I've found you need very high quality source, cabling, amp etc. before good subwoofer bass is possible, for music. Feel free to disagree, thats just what I feel I've noticed.
- subwoofer's phase needs reversing/tweaking - use a sine wave or something at the x-over frequency, and when loudest, the phase setting is probably optimal.
I like corner placement btw, my 250l (tuned to about 20hz) ported tempest sits in the corner, which makes sense, because you excite all room modes equally, and get the most room gain, and that means less work for the sub. I think I use a fraction of my subs capability, and I use a 150w rms/4ohm plate amp btw. Adding extra capacitance to the amp's psu solidified the bass.
From the (admittidly not many) amps I've heard and seen the DF spec of, there seems to be a good correlation between a higher number and more controlled bass... (despite the science disproving it over very small figures)
Btw, is your living room large? Because if it is, those room modes will be a nightmare with such a capable sub. Sorry to point out the obvious!
(my room is too small for modes below 50hz, where the sub kicks in...)
- integration with main speakers isn't working quite right: too big a peak or dip, or too different quality even. Are the main speakers sealed or ported? Might be a consideration.
- room modes are killing the subjective speed, as said already
- you simply aren't used to the subjective change of pace when hearing more extended bass output. Usually fast, tight, punchy bass just means cutting off anything below about 60hz, so if you've not thought about that effect, bear it in mind
I've found you need very high quality source, cabling, amp etc. before good subwoofer bass is possible, for music. Feel free to disagree, thats just what I feel I've noticed.- subwoofer's phase needs reversing/tweaking - use a sine wave or something at the x-over frequency, and when loudest, the phase setting is probably optimal.
I like corner placement btw, my 250l (tuned to about 20hz) ported tempest sits in the corner, which makes sense, because you excite all room modes equally, and get the most room gain, and that means less work for the sub. I think I use a fraction of my subs capability, and I use a 150w rms/4ohm plate amp btw. Adding extra capacitance to the amp's psu solidified the bass.
From the (admittidly not many) amps I've heard and seen the DF spec of, there seems to be a good correlation between a higher number and more controlled bass... (despite the science disproving it over very small figures)
Btw, is your living room large? Because if it is, those room modes will be a nightmare with such a capable sub. Sorry to point out the obvious!
(my room is too small for modes below 50hz, where the sub kicks in...)Strange thread this one, as if subwoofers produce bass,
they don't, they produce bass fundamentals, quality of bass
reproduction is 90% the full range speakers*, the subwoofer
hopefully doesn't make it any worse and adds extension.
I like others would first point the finger at intergration issues,
its surprising the number of bass subwoofer amplifiers that
cannot be set to low enough frequency once room gain is
considered if the main speakers are run full range.
A high Q sealed box is simply not going to help IM0.
Amplifier damping factor is simply not an issue.
Details of the main speakers, type (reflex are difficult to
integrate with a sub) and placement would help.
If reflex blocking the ports will help with integration.
sreten.
*I play bass and am an affecienado of good bass reproduction.
they don't, they produce bass fundamentals, quality of bass
reproduction is 90% the full range speakers*, the subwoofer
hopefully doesn't make it any worse and adds extension.
I like others would first point the finger at intergration issues,
its surprising the number of bass subwoofer amplifiers that
cannot be set to low enough frequency once room gain is
considered if the main speakers are run full range.
A high Q sealed box is simply not going to help IM0.
Amplifier damping factor is simply not an issue.
Details of the main speakers, type (reflex are difficult to
integrate with a sub) and placement would help.
If reflex blocking the ports will help with integration.
sreten.*I play bass and am an affecienado of good bass reproduction.
SimontY said:
While I won't disagree with you liking corner placement I disagree
completely with your reasoning. Corrner placement gives maximum
exxageration of room modes compared to the frequencies inbetween,
however sensible placement for smooth bass is entirely impractical
so 1/3 along the back wall is the best that most people can do.
Best placement is near 1/3 along all room dimensions, which only
makes sense for a loudspeaker with built is stereo subwoofers.
But you seem to be implying your small room does not support
room modes in the frequency range of your subwoofer, in this
case placement is entirely uncritical, and assumptions of the best
position for the subwoofer cannot be made.
Power requirements below room modes cannot change with placement.
Your reasoning appears to be contradictory.
sreten.
Can you please rephrase that so it makes sense to me?sreten said:
I thought the fundamental is simply the main part of the note/tone, [and harmonics just sit on top of this]. Being a bass guitar player you *would* account most bass quality to your main speakers, as the bass only goes to about 40hz, iirc.You seem very knowledgable, do you think its an easy thing to adjust something in the circuit, on a plate amp, that would shift the x-over down a tad? (e.g. I use 50hz, but 45hz might be more apt, as my speakers are still ok to the high forties, and things pile up at 55-60hz, where there is a room mode)
I sort of (quite possibly, mistakenly) had the impression that sealed box speakers were harder to integrate. (could this be the more shallow roll-off, or the transient response superiority, which will be better than the sub, most likely?)
Yeh, fair enough, it was crap. Give a hungover flid a break will ya!sreten said:
That will depend on where the sub is rolled off, and the size of the room. If this guy has a very big room and an f2 mode is causing the trouble then 1/3 sounds good, and good for f1 too (but I'd want some room mode gain at very low frequencies
)Yeh, dam right
But disregarding specific systems, there are clearly 2 camps - one who like the corner, one who avoids the corner. Each setup will surely have a different optimal positioning etc. But anyone who has the space to experiment with a Tempest-sized sub... well, I'm envious! Dam yanks, with your massive rooms!!
Actually, this is an area I don't know enough about to dispute such a comment, but... I thought room gain at very low frequencies (smaller the space, the more gain e.g. cars have lots of extra low bass for free) was boosted more close to boundaries. Fine if I'm wrong, but at least politely correct me if you know bettersreten said:
(I didnt have room modes in mind, and actually I'd love to put my sub somewhere impractical to look for better results, but it is in the only place it can go, and it works quite well! ..oh, and I suppose I sort of had in mind having the sub near the listener - mine is <1m away from the listener - I was thinking of this too, in my own corner setup )
grampi said:
It sounds to me that your setup is simply out of whack. You might have too much low end dialed in, wrong crossover frequency, wrong polarity on the sub, wrong position in the room or most likely a combination of above factors.
There is a very good article on digital domain's web site. Read it and try to follow it. I guarantee you will like what you hear when it's all said and done.
Here is the link
Smaller the space more gain true - but this is at
frequencies where boundaries have no effect.
Disconnect your main speakers and you should see what I mean.
Even organ pipes will have "bass" but no tone. Most bass sounds
will be unrecognisable.
not easy to do unless the maker will give circuit details.
Simply double all capacitor values in the relevant circuit
section to half the frequency range of the subwoofer.
Most subs have a 2nd order rolloff, Butterworth or Linkwitz/Riley.
24/dB reflex main speaker rolloff makes the frequency setting of
a sub more obvious, but ultimately a 2nd order main speaker
roll-off should integrate with the subwoofer better, especially
for the L/R sub and reflex speaker -> sealed case, out of phase.
I'm standing by this when room modes are significant. At frequencies below room modes placement is not significant.
sreten.- Status
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