| navin |
I am told that the JX92 demands a quality subwoofer. none of those 12" dia 1" Xmax driver (shiva, temepest, etc....) will mate with it properly.
i intend to feed the JX 92 from a HT/AVR (Marantz SR7000) and th sub would be fed from the sub out of the same HT/AVR (100hz).
what sub designs can you guys recommed considering WAF.
I was considering the follow:
2 woofers in a dipole (can anyone recommed any 8-10" woofers for this as the DPL12 might be too big and slow).
2 woofer is 2 narrow (10:1) tapered TLs. these woofers would be in shallow enclosures againt a wall or in a corner.
2 woofers in a small 3-4 cu. ft. sealed box under the sofa.
BTW I do have 4 (DV12) 12" from audio concepts lying around. should i even attempt mating these to the JX92? |
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| zobsky |
| 1 autotuba horn sub with its 8" driver should do you fine (ignore the unimpressive looking SPL graph, .. no lack of low bass in reality), .. though you might have the converse issue of the jx92 not being able to keep up with the sub :) |
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| Bill Fitzpatrick |
| quote: | Originally posted by navin
I am told that the JX92 demands a quality subwoofer. none of those 12" dia 1" Xmax driver (shiva, temepest, etc....) will mate with it properly.
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I don't believe that.
| quote: | Originally posted by navin
BTW I do have 4 (DV12) 12" from audio concepts lying around. should i even attempt mating these to the JX92?
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You certainly should. |
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| navin |
thanks bill.
zobsky, would love to see a link on that 8" autotuba bass. |
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| smallangryboy |
| I'm also in the process of designing a sub to partner some Jordan monitors ! Going for a more conventional [and wife friendly] compact design, with a single 12" driver in a 50L sealed enclosure and would be interested to hear views on appropriate driver/amps that would be up to the job. I need them to be easily available in the UK though !!! |
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| Dave Jones |
I've just finished a pair JX92S monitors that I'm running with a Peerless 10" XLS passive radiator sub in my office. The sub enclosure is about 1ft^3. In the room, it's flat to 20Hz except for a +12dB node at 45Hz, due to the room no doubt. I've got an EQ on it to kill that node. I can't imagine anything could sound much better in a 14'X18' room with 12' ceilings. The mains are in a .3ft^3 sealed box, and employ BSC's of L=1.5 mH, R = 3.9 Ohm. There's no high pass filter on the mains. I'm crossing over to the sub at about 80 Hz.
Maybe in the next few days I'll start a thread with pictures. |
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| Dave Jones |
| quote: | Originally posted by smallangryboy
I'm also in the process of designing a sub to partner some Jordan monitors ! Going for a more conventional [and wife friendly] compact design, with a single 12" driver in a 50L sealed enclosure and would be interested to hear views on appropriate driver/amps that would be up to the job. I need them to be easily available in the UK though !!! |
The PartsExpress 12" Titanic Mark III models real well in a sealed box that size. If you use a little boost at 20Hz, the response starts to fall at around 40Hz and is down 6dB at 22Hz or so. With room lift, that might be just about perfect. PE has recently published resistor values for adjusting the boost on their 804 240 watt plate amp, which has a 24dB lowpass filter. If I were going to build another sub, I think I might give that combination a try. I don't have any idea how much it would cost to ship the stuff to the UK. |
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| navin |
| thanks guys. i think i will look at using the 12" drviers i have. if the peerelss XLS and Titanic can integrate well I guess the DV12 can do too. |
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| Dave Jones |
| quote: | Originally posted by Dave Jones
I've just finished a pair JX92S monitors that I'm running with a Peerless 10" XLS passive radiator sub in my office. The sub enclosure is about 1ft^3. In the room, it's flat to 20Hz except for a +12dB node at 45Hz, due to the room no doubt. I've got an EQ on it to kill that node. I can't imagine anything could sound much better in a 14'X18' room with 12' ceilings. The mains are in a .3ft^3 sealed box, and employ BSC's of L=1.5 mH, R = 3.9 Ohm. There's no high pass filter on the mains. I'm crossing over to the sub at about 80 Hz.
Maybe in the next few days I'll start a thread with pictures. |
Off topic, but I killed that nasty node at 45Hz. It was simply a matter of moving the sub around in the room until I found just the right spot. It's now razor flat to 20Hz with no EQ. |
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| Dave Jones |
| quote: | Originally posted by navin
pics dave pics! |
See the thread named "JX92S monitors." Pictures of the sub are in the thread "Locust I." Due to chronic clinical laziness, the sub enclosure is still raw particle board. |
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| Colin |
Hello smallangryboy
There's a purpose-made powered sub on the Jordan website (www.ejjordan.co.uk/systems) manufactured by MJ Acoustics. |
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| smallangryboy |
Colin
Thanks for the link. I have seen that before and did have a chat about it with Ted Jordan.
However we were looking at our own solution to sell with our satellites, and didn't want a third party like MJ involved.
I've not heard the Jordan based Pro 50 but the MJ version has had mixed press, especially on the AV forums.
Currently we are working with John at Acoustic Elegance in the US, as he makes some very high quality sub drivers, based around the Lambda Acoustics LB12, and a 350w dedicated plate amp to partner it. I'm just waiting for the prototype to arrive but was measuring up some home grown alternatives in case it didn't work out. |
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| smallangryboy |
| quote: | Originally posted by Dave Jones
The PartsExpress 12" Titanic Mark III models real well in a sealed box that size. If you use a little boost at 20Hz, the response starts to fall at around 40Hz and is down 6dB at 22Hz or so. With room lift, that might be just about perfect. PE has recently published resistor values for adjusting the boost on their 804 240 watt plate amp, which has a 24dB lowpass filter. If I were going to build another sub, I think I might give that combination a try. I don't have any idea how much it would cost to ship the stuff to the UK. |
Dave
On the PE website they have the Titanic partnered up to a 500w amp, I'm not sure if I could use this here in the UK as it doesn't say the power supply is switchable. Just wondered if the 250w amp would be OK to drive the Titanic ?
Also, not sure I want to go delving into the guts of the amp changing resistor values, a bit beyond me, wondered if this would have a big impact just using the amp 'as is' with the driver ? |
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| Dave Jones |
| quote: | Originally posted by smallangryboy
Dave
On the PE website they have the Titanic partnered up to a 500w amp, I'm not sure if I could use this here in the UK as it doesn't say the power supply is switchable. Just wondered if the 250w amp would be OK to drive the Titanic ?
Also, not sure I want to go delving into the guts of the amp changing resistor values, a bit beyond me, wondered if this would have a big impact just using the amp 'as is' with the driver ? |
The 250W amp might give you a few dB less max volume. I don't know.
Concerning the resistors, on the amp that I modified, it was not difficult at all. The only moderately hard part was removing the internal cover to the preamp. But that was a different unit.
As an alternative, you could get a plate amp with a built-in parametric equalizer. Those are more expensive, but some would allow you not only to add the boost, but also kill a room node.
I am attaching modeled FR plots for a system in a 48 liter box both with 4dB boost at 20 Hz, and without boost. The no boost graph is obviously inferior.
Here's the one with boost: |
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| Colin |
How about one of the Gainclone variants for the sub amp? I'm sure Peter or Brian would be able to help with modifications.
Colin
PS I've heard Ted's modified MJ sub and it works well with his Linear Array. I can understand, though, if you want to keep it all under one roof. |
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| JVA |
Adire Extremis 6.8
I heard them at C.S.S. they have excellent solid fast bass due to there small size . A couple of these drivers in a 40 to 50 liter box vented or sealed box would probably keep up with fast bass of the Jordans.
J V A. |
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| planet10 |
| quote: | Originally posted by smallangryboy
Currently we are working with John at Acoustic Elegance in the US, as he makes some very high quality sub drivers, based around the Lambda Acoustics LB12, and a 350w dedicated plate amp to partner it. I'm just waiting for the prototype to arrive but was measuring up some home grown alternatives in case it didn't work out. |
I'm having trouble getting used to the Acoustic Elegance name -- John will probably always be Stryke to me. i sure hope John can resurrect Llambda -- some of the best woofers ever made. John has a better business head on him, and is smart. He is young thou and has been beset by a few set-backs (having tochange names probably a minor one)
dave |
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| smallangryboy |
Yes he sounds keen, and it's just a case of making sure his success doesn't get the better of him. He sounds like a really good bloke and I hope his success continues.
As I understand it he is inundated with orders for his drivers, especially the AV12, one of the most popular and one which I had originally intended to use, however he has quite a severe backorder on many of his drivers, one of the reasons my financial backer demand we look to other avenues as well for supply. |
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| Dave Jones |
| quote: | Originally posted by JVA
Adire Extremis 6.8
I heard them at C.S.S. they have excellent solid fast bass due to there small size . A couple of these drivers in a 40 to 50 liter box vented or sealed box would probably keep up with fast bass of the Jordans.
J V A. |
When you use the expression "fast bass" on this BB, the slap-down is usually pretty quick. Be ready. :-) |
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| GM |
| quote: | | When you use the expression "fast bass" on this BB, the slap-down is usually pretty quick. Be ready. :-) |
LOL! :D Lookee! The bass is so 'fast' only a tweeter is needed to reproduce it! ;)
GM |
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| JVA |
GM Loud is beautiful if its clean ,maybe the word CLEAN is what I was thinking of,or maybe clean bass,or am I still saying it wrong. Is there such thing as fast bass.
Enlighten us , CLEAN our newbe minds of such dastardly words as FAST BASS
JVA |
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| JVA |
While i'm on a roll, fast bass out here could mean a junk fish that got away, or you can take the B , off . I better not go there.
JVA |
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| Dave Jones |
| quote: | Originally posted by JVA
GM Loud is beautiful if its clean ,maybe the word CLEAN is what I was thinking of,or maybe clean bass,or am I still saying it wrong. Is there such thing as fast bass.
Enlighten us , CLEAN our newbe minds of such dastardly words as FAST BASS
JVA |
(I'm not GM, but then, who is?)
"Fast bass" is a pretty common term. The question is, what do people mean by it? Maybe they don't all mean the same thing. Someone, (Lynn Olsen?), said he thinks people use the expression for bass that has low IM distortion. In any case, bass is, by definition, slow.
Although I'm still driving on my learner's permit, I venture this: In order to get clean bass with some volume to it, you have to move a lot of air. In a small room, it might be possible to move enough air with smallish drivers with a modest xmax. It would depend on your expectations. But small drivers also tend to have high Fs, which is not a Good Thing for bass either.
Getting back to the original question, let me just reiterate that I'm using a 10" Peerless XLS with a 400 gram passive radiator in a 26 liter box with my Jx92s's, and I could not be more pleased. The mains are in sealed boxes. I'm running them with no high pass filter. The sub's low pass is set at around 80 Hz. It's in an office that's about 14' x 18' X 10', but judging by how much I have to turn it down, I think it would do quite well in an average size living room, except maybe for the lowest quarter octave. |
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| navin |
| quote: | Originally posted by Dave Jones
Although I'm still driving on my learner's permit,....It's in an office that's about 14' x 18' X 10' |
you are still to get a driver's licence (presumably because you are a bit young) but you are old enough to go to an office? :-)
seriously what i understand by "fast bass" is the attack. the attack is actually a combination of the bass note as well as it's over tones. if you take a bass guitar (the low E goes down to about 42hz) you can either create a pure sine wave at 42Hz or a complex wave (by slapping the strings for example) that includes other overtones and by that nature sounds fast.
music usually is a mix of simple and complex sounds. everyone has his/her own definition of what constitues music and what does not. as a rule most of do NOT visit as many live concerts as we should or wish too and hence dont recalibrate our ears often enough. this is probably the source of the confusion. |
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| argo |
"Fast" is common expression in audio mumbo-jumbo, as is another idiom - "speed" (ever heard of amplifier speed). Of course, a bass as low frequency sound can be as "fast" as are its frequencies it reproduces. A better word would be “quick” - quick to react or quick to go and quick to stop. In other words good acceleration and stopping speed. But not only that. One can say that a drag racing car is a “fast” car but try to compete with it on formula circle or on rally special stage. It just can’t react to the changes of the track as “fast” as F1 or WRC car.
As navin sayd, the bass in the music is seldom only a single note but several instruments playing a multitude of different notes (frequencies) or accords at warring speed and producing their accompanying harmonics at the same time. So how would you describe a low frequency transducer that can truthfully reproduce all that? |
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| navin |
[QUOTE]Originally posted by argo
[B.... So how would you describe a low frequency transducer that can truthfully reproduce all that? [/B][QUOTE]
Perfect?
:D |
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| Dave Jones |
| quote: | Originally posted by navin
seriously what i understand by "fast bass" is the attack. the attack is actually a combination of the bass note as well as it's over tones. |
The overtones don't come out of the subwoofer. They come out of the mains. |
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| GM |
| quote: | | Enlighten us , CLEAN our newbe minds of such dastardly words as FAST BASS |
Greets!
The lower the frequency, the wider its BW, ergo DC = infinite BW, but a speaker normally has multiple drivers electrically isolated from each other by XOs so that the woofer handles the lowest fundamentals and their first few harmonics (slow), the mid driver the middle harmonics (faster), and the tweeter the leading edge of all that came before them (fastest). Note that 'fullrange' drivers have built in mechanical XOs so are self contained multiple discrete BW systems.
From this it's obvious that the woofer section is by definition 'slow' because the WLs are long and all of the leading edge and middle harmonics that defines its 'speed' are being reproduced by other systems. To say a typical sub that's BW limited to ~3 octaves is 'fast' is at first glance not only technically incorrect, it's just plain ludicrous, hence some folk's brutal rebuttals.
Factor in our falling hearing acuity with decreasing frequency and when tested outdoors well away from any boundaries it's very hard for most folks to hear any difference between various BW limited sub systems that have wildly varying Qtc, or even type of cab design, beyond how loud each one is for a given frequency compared to the others.
Still, once these slow/dull sounding systems are confined in an acoustically small space, and even more so when the rest of the LF BW (mids/highs) is added, we sense differences (sometimes major) in these systems that leave most folks 'grasping at air' trying to verbalize them. At this point Mother Nature takes over as even the most technically illiterate innately understands the concept of DC = infinite BW because the more HF BW we hear/feel, the 'fuller' the bass sounds *even if the corresponding fundamentals are missing* and vice versa when the extreme highs are missing from an otherwise super wide BW sound. Even if BW limited at both ends we are 'Happy Campers' if the tonal balance mirrors our speech power response, and why a telephone's very limited BW (~3.3 octaves) sounds sufficiently wide for all but critical listening. Seems our internal sound processor has a very elaborate EQ/synthesizer built into it.
Viewed from this perspective, 'fast' seems the obvious 'catch-all' adjective to define the system's ability to sound tonally balanced, i.e. ~accurately reproducing the signal from top to bottom, however wide or narrow it may be (within reasonable limits of course).
Being a 'catch-all' word like 'clean', 'muddy', etc., and factoring in that folks differ as to how they perceive certain sonic attributes of a system it can mean timing to one person, phase to another, a rising response to another, excessive comb filtering between discrete systems, etc., though really it's all of them, with only the perceived importance of each shifting among them based on our physical/emotional make-up.
So we understand in general what someone is trying to tell us about a system's accuracy, but don't have a clue what they're specifically referring to unless they further define whatever adjective they're using to describe their subjective feeling of how 'right' or 'wrong' it sounds, ergo lacking this info we naturally 'weight' it based on our own perceptions, which can be poles apart from what the author intended to convey.
Little wonder then that folks can get into extremely venal 'debates' over a phrase such as 'fast bass' when no narrowly defined definition can be agreed upon due to it being at once ludicrous and technically correct when the audio system is being reviewed both as a whole and as a collection of interconnected discrete systems, with the room's impact usually being an unaccounted for 'wild card'.
As always though, YMMV and "it's just my opinion, I could be wrong" (after Dennis Miller). ;)
GM |
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| Dave Jones |
| quote: | Originally posted by argo
"Fast" is common expression in audio mumbo-jumbo, as is another idiom - "speed" (ever heard of amplifier speed). Of course, a bass as low frequency sound can be as "fast" as are its frequencies it reproduces. A better word would be “quick” - quick to react or quick to go and quick to stop. In other words good acceleration and stopping speed. |
The fast start (attack) is handled by the mains.
Bass notes typically stop (decay) much more slowly than loudspeaker is capable of starting and stopping. Reverberation in the room also continues long after the loudspeaker has stopped responding to the program source.
A loudspeaker that stops as quickly as possible without overshoot has a Qts of 0.5. A few months ago I read some heebie jeebie on a website and got all excited about building a subwoofer with a Qts of 0.5. The whole concept turned out to be so much bunk. A sub with a Qts of .7 or even 1.0 is plenty quick enough.
From what I've been able to learn over the last few months, a good subwoofer is one that has low distortion and is capable of moving enough air for the program material and listening room. If the sub has nasty breakup modes in the midrange, as many do, it needs a high order lowpass filter. Probably the most effective thing that can be done to make a sub sound "speedy" is to eliminate room reverberation, or failing that, EQ around it. |
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| Bill F. |
GM and Dave, amen and amen.
It's a rare thing to see two consecutive posts on this topic of such high quality.
| quote: | | A sub with a Qts of .7 or even 1.0 is plenty quick enough. (snip) Probably the most effective thing that can be done to make a sub sound "speedy" is to eliminate room reverberation, or failing that, EQ around it. |
In support of this, I cite my current 21" bass units on open baffles. Their Qts is somewhere around 1.3 and their cones are large and heavy. Some might say they're the perfect recipe for "slow" bass. Yet, on open baffles, they are things of sonic beauty, truth, and grace. The room intereaction (or relative lack thereof) really is the huge factor. |
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