Hi, complete diy newby here.
I'm wondering how one can modify a bought sub to be more musical/tight/fast.
I'm thinking of matching a sealed 12" sub(-3db@25hz) with some fast electrostatics. From my cursory reading it seems that Q is the issue? Is it all about "critically dampening" the sub or is there more to it than this? What numbers should I be aiming for?
What, if anything, could I as a novice do to tighten up the sub? I have friend who is an EE so if there is something to be done involving the PCB then please also let me know.
I should also say that I am happy to sacrifice some ectention(say 30hz) and lots of output to achieve my end.(I dont listen over 80db).
Thanks for any help.
b.
I'm wondering how one can modify a bought sub to be more musical/tight/fast.
I'm thinking of matching a sealed 12" sub(-3db@25hz) with some fast electrostatics. From my cursory reading it seems that Q is the issue? Is it all about "critically dampening" the sub or is there more to it than this? What numbers should I be aiming for?
What, if anything, could I as a novice do to tighten up the sub? I have friend who is an EE so if there is something to be done involving the PCB then please also let me know.
I should also say that I am happy to sacrifice some ectention(say 30hz) and lots of output to achieve my end.(I dont listen over 80db).
Thanks for any help.
b.
It's not a lot really to do with Q, especially if the box is sealed. The factor is integration - the low-pass filter.
bvan said:
Hi,
Investigate the stuffing of the subwoofer. Depends on the driver
and the current type of fill and its density. increasing stuffing will
tighten bass though as said integration of the sub and the
electrostatics is also critical.
🙂/sreten.
Thanks for that.
I have a BFD if that helps with intergration? I take it you mean that the subs and speakers roll-off slopes must be such that there are no holes or humps?
So increasing the stuffing inside the speakers would help? Why do manufacturers skimp on this i.e what is the tradeoff of putting too much dampening material in the enclosure?
cheers
b.
I have a BFD if that helps with intergration? I take it you mean that the subs and speakers roll-off slopes must be such that there are no holes or humps?
So increasing the stuffing inside the speakers would help? Why do manufacturers skimp on this i.e what is the tradeoff of putting too much dampening material in the enclosure?
cheers
b.
Q will raise making a peakier response and worse group delay, and low-extension will reduce. Power handling will be improved provided you have not reached the voice coil thermal limit.
Bear in mind that changing Qts from e.g. 0.7 to 0.9 is only quite suttle.
Bear in mind that changing Qts from e.g. 0.7 to 0.9 is only quite suttle.
I think I found what I'm looking for! Will start from scratch:
http://www.customanalogue.com/sub_index.htm
A "critical Q" sub, Q=0.5, designed for music not HT.
What you guys think? look easy enough to build.
cheers for the help,
b
http://www.customanalogue.com/sub_index.htm
A "critical Q" sub, Q=0.5, designed for music not HT.
What you guys think? look easy enough to build.
cheers for the help,
b
http://www.diyaudio.com/forums/showthread.php?s=&threadid=81892
Will add that the peerless drivers are meant to be fantastic drivers, just be wary of believing all on the critical q site. Esp. the measurement bits.
Rob.
Will add that the peerless drivers are meant to be fantastic drivers, just be wary of believing all on the critical q site. Esp. the measurement bits.
Rob.
I wonder what exactly you mean when you say tight. A well designed woofer with a Q of 0.5 should indeed give you tight bass.
This bass might be accurate, gentle and articulate (for want of a good set of descriptive words). It will play well with most types of music.
However, if you listen to much rock music, or anything with a bit of sting, you might favour something different. Perhaps a system with a higher Q, and an amp with a high damping factor maybe.
FWIW, I use a low Q setup and find all music listening enjoyable.
This bass might be accurate, gentle and articulate (for want of a good set of descriptive words). It will play well with most types of music.
However, if you listen to much rock music, or anything with a bit of sting, you might favour something different. Perhaps a system with a higher Q, and an amp with a high damping factor maybe.
FWIW, I use a low Q setup and find all music listening enjoyable.
Can one talk about 'acurate' in absolute terms? i.e is 0.5 'more acurate' than 0.7. You would then think more speakers and subs would have low Q wouldnt you?
Why would higher Q sound better with strings? Is a higher Q more accurate with strings and a lower Q more accurate in reproducing drums say?
thanks
b
Why would higher Q sound better with strings? Is a higher Q more accurate with strings and a lower Q more accurate in reproducing drums say?
thanks
b
I have one opinion and I expect others to have their own. That said...
I find a low Q system to sound accurate in that the instruments sound like they should. They are exciting in a subtle but breathtaking way.
I have had others listen to my system and they want to find the treble and bass controls so they can 'crank' them. My system doesn't sound like a commercial mid-fi system does.
Many commercial mid-fi systems have a higher Q bass (or reflex). This can give more 'kick', and can offer a buzz out of heavier music. The instruments don't always sound as much like they are in the room with you though.
Since, though, we are all probably capable of building a system that's better than mid-fi, my guess is that your compromise won't be that large.
I encourage you to take other's opinions too. 🙂
I find a low Q system to sound accurate in that the instruments sound like they should. They are exciting in a subtle but breathtaking way.
I have had others listen to my system and they want to find the treble and bass controls so they can 'crank' them. My system doesn't sound like a commercial mid-fi system does.
Many commercial mid-fi systems have a higher Q bass (or reflex). This can give more 'kick', and can offer a buzz out of heavier music. The instruments don't always sound as much like they are in the room with you though.
Since, though, we are all probably capable of building a system that's better than mid-fi, my guess is that your compromise won't be that large.
I encourage you to take other's opinions too. 🙂
Some refs:
Adire Audio on Woofer Speed.
John Kreskovsky on Sealed Enclosures
Art Ludwig on Thiel/Small analysis, especially the section comparing Enclosure Types.
Personally, I believe accurate is a matter of personal taste. I've heard horns that are blindingly accurate when it comes to the speed, percussiveness, etc of the performance, yet are tonally unbalanced compared even to mid-fi. And I've heard stuff that seems to produce the tonal balance of instruments extremely well, yet the notes themselves don't attack the way they should, and the soundstage is smeared "across the horizon". Most microphones cannot record the sound 'accurately' in the first place - even the best will produce a different recording when placed in a similar set-up. Not to mention that the interacting harmonics of the sound will now be recorded as well.
As most rock music takes place above 40Hz, a higher Q system for this is not "necessary". But to cope with most music (and - heresy - also for your HT) you would probably want a low-Q woofer set-up for all regular playing, PLUS a "real" subwoofer to handle those 16Hz organ pipes and the explosions from Star Wars.
Mine is a pair of Q=.577 12" Lambda in sealed boxes (F3 ~50Hz), plus a yet-to-be-completed 2x15" Iso sealed sub-woofer. The latter is awaiting spousal approval... Without the the subby, the sound is indeed 'tight' and 'fast', but not real world. Some pieces just need that bit of extra impact. (Sigh) It was so much simpler when I was single 🙂
Adire Audio on Woofer Speed.
John Kreskovsky on Sealed Enclosures
Art Ludwig on Thiel/Small analysis, especially the section comparing Enclosure Types.
Personally, I believe accurate is a matter of personal taste. I've heard horns that are blindingly accurate when it comes to the speed, percussiveness, etc of the performance, yet are tonally unbalanced compared even to mid-fi. And I've heard stuff that seems to produce the tonal balance of instruments extremely well, yet the notes themselves don't attack the way they should, and the soundstage is smeared "across the horizon". Most microphones cannot record the sound 'accurately' in the first place - even the best will produce a different recording when placed in a similar set-up. Not to mention that the interacting harmonics of the sound will now be recorded as well.
As most rock music takes place above 40Hz, a higher Q system for this is not "necessary". But to cope with most music (and - heresy - also for your HT) you would probably want a low-Q woofer set-up for all regular playing, PLUS a "real" subwoofer to handle those 16Hz organ pipes and the explosions from Star Wars.
Mine is a pair of Q=.577 12" Lambda in sealed boxes (F3 ~50Hz), plus a yet-to-be-completed 2x15" Iso sealed sub-woofer. The latter is awaiting spousal approval... Without the the subby, the sound is indeed 'tight' and 'fast', but not real world. Some pieces just need that bit of extra impact. (Sigh) It was so much simpler when I was single 🙂
I agree with Rob on taking the 'Critical Q' sub and it's writeup with a pinch of salt. Also a good point from lndm about what you want - I've known people think 'fast' is damped and articulate as lndm said, but others think it's a punchy sound that adds an element of pace to the music. You need to think more about the sound you want.
Bear in mind though that the placement will matter at least as much as any tweaks you do to the design.
Bear in mind though that the placement will matter at least as much as any tweaks you do to the design.
Hi,
I'll add I also think the "Critical Q" write-up should be ignored.
Design based on waffle is not design, it's wishful thinking.
I'll also add the following :
The high pass roll-off (i.e. low frequency roll-off) of the sub is one issue.
At least as important is the low pass roll-off of the sub and its
integration with the high pass roll-off of the electrostatics, and
this can be dominated by in-room gain and room resonances.
Using two subs is one route to reducing room effects.
🙂/sreten.
I'll add I also think the "Critical Q" write-up should be ignored.
Design based on waffle is not design, it's wishful thinking.
I'll also add the following :
The high pass roll-off (i.e. low frequency roll-off) of the sub is one issue.
At least as important is the low pass roll-off of the sub and its
integration with the high pass roll-off of the electrostatics, and
this can be dominated by in-room gain and room resonances.
Using two subs is one route to reducing room effects.
🙂/sreten.
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