No sub = no bass... true? - Page 13 - diyAudio
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Old 19th December 2011, 05:51 PM   #121
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Quote:
Originally Posted by canonnica View Post
This explanation means that even if I put huge speakers that delivers big bass, it will still cancel completely when I'm not in the perfect listening spot.

Now the problem is explained, yeah! A solution is needed now... It seems that having a single source for bass will prevent wave cancellation. A single subwoofer seem the automatic choice. I was thinking of a sub with line-input that has a 80Hz high-pass line-output, so my now called "satellite" speakers won't reproduce those frequencies that cancels out and the sub will take care alone of whatever below 120Hz-80Hz or so.

Am I too simplistic? Seems almost too simple as an explanation but hey, I tried with either speaker unplugged and bass is now propagating.

Any suggestion for a DIY sub? Should I switch to the "Sub" section of the forum and consider this thread over?

Thanks,
Martin.
Au contraire... rather than less sources, you actually need more - about four or five - at which point spatial averaging will kick in and give you ruler flat response +/- 3db or better. You already have two sources, so adding three 12" subs is recommended - and forgo the crossover unless you need it for power handling purposes. I stick by my 2X or 3X or even 4X SEPARATELY PLACED Trio 12 + LT suggestion.

Also, setup is KEY. Finally, you could consider some bass traps. Filling corners with 8" to 12" floor to ceiling of absorption material can make a huge measurable difference. Now the mode near 70hz tends to be floor-ceiling FWIW. One way to address it may be a sub loading the ceiling from a different vertical location. I dunno.

Quote:
Originally Posted by River757 View Post
+1

The price for a subwoofer (or loudspeaker) seems to increase almost exponentially for every 10Hz further down you want it to reach....and I just don't have the $$ for that, particularly when I am not even sure my type of music - mostly rock, which usually seems to fizzle out around 35Hz - has anything down there to reproduce. And while I'm not all that concerned about the size of a speaker, an 8 cu/ft enclosure or something similar to that squatting in my living room is just too much to deal with.
The Trio 12 is $150 for the driver... factor in a 300-500w amp, and then some EQ (IE MiniDSP?) to change response including an F3 = 18hz @ Q = .5g as well as toning down major room mode peaks. A sealed box can be 2 to 3.5 cu ft for excellent results. Remember adding subs won't just improve extension but in-room frequency response in the midbass as well - leading to a more defined bass guitar and a snappier kick drum in rock music. The Trio 12 has shorting rings which means it should have fine sound quality.

I gotta say I don't consider that overly expensive as that is reference level stuff for music. Now getting the deep deep stuff for HT purposes (> 115db @ 20-120hz, > 110db @ 10hz> 105db @ 5hz) is overly expensive and convoluted... and really starts with a custom, leak-free room for best results. It requires lots of volume displacement, lots of amplification for EQ boost, lots of available line current for those amps electronics, and amps/electronics with unusually flat behavior below 10hz, and plenty of room gain.

Quote:
A single source for bass applies outdoors, not where boundaries are involved, ie in a room. This is just the foundation, frequency wise, of this entire conversation. Low frequencies are omnidirectional they say. Then the reflections and standing waves show up. Very soon. More woofers, thoughtfully dispersed, are what works. Or live in a tent, with real musicians.
Well, for box speakers at least. Gradient speakers do have "directional" bass but the tradeoff there is very low efficiency as you go down in frequency.

Quote:
I would be very interrested in measuring the freq. response of my room. Do you have affordable tools to suggest?
You could start with an Omnimic.
or a Dayton EMM-6 + USB Phantom Power

I highly recommend having measurement gear. Accurate bass without it is extremely optimistic.

Quote:
That's interresting... Does the usage of a Linkwitz transform circuit eliminates the need for an active crossover (like in the typical plate-amps) or is it to compliment it?

I'm tempted in building my own simple sealed 2cu.ft. with their 12" driver and a matched Linkwitz circuit to extend its response I just wonder how that circuit will integrate with a plate-amp. And they're in Canada too...
Okay here's the deal. A linkwitz transform circuit will extend bass response but that's it.

However a plate amp will have a high pass filter, which will be counterproductive for a music-only build with an LT.

Also, plate amps do not have crossovers either. I would personally never use the high level inputs on a plate amp. If using a plate amp you have to accept that it's probably optimized for best power handling (with a high pass filter) and also accept that you will want an external device connected to an amp to connect the subs. A really effective method is an HT receiver with the mains set to "large" and the sub set to "both". With this method, your sub plays notes below 120hz (or whatever frequency you choose) as do you mains. with the additional source of bass in room your frequency response will tighten up. You can play around with subwoofer placement and phase to see the effect on global response.

My suggestion would be to get two Trio 12 drivers and a good outbound amp to drive them.

This is an amp that can drive two, (maybe even four) trio 12s effortlessly:

Crown XLS1500 DriveCore Series Power Amplifier with 2 x 300W at 8 ohms | Vancouver Montreal Toronto Canada

However if you do want to use the plate amp offered by CSS, try getting in touch.. you might be able to get it modified "for music only" (watch out for movies though... if using an LT'd, non highpassed sub for movies at higher SPLs, you could easily damage a driver).

as for the linkwitz transform, a MiniDSP should handle that, or you can do an analog one. Either way, save this EQ business for afterwards (you might not need an LT for 90% of music, though as was discussed earlier, the LT can bring some music to life with a HUGE soundstage). I'd start with just getting some drivers, boxes, and amps. Then maybe if you want, you can work in some measurement gear to see how things measure. Finally, if your room has some problems you can fix, they should, with four sources of bass, be mostly minor peaks that you can EQ down with some notch filters effectively (bass in rooms is minimum phase). for all we know, with room gain you may get meaningful bass to 20hz anyways.

Now if you don't have an HT receiver that can integrate subwoofers into your system, I recommend the miniDSP regardless as it can also serve as a lowpass filter for the subs.
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Old 19th December 2011, 06:31 PM   #122
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I want to clarify something

Quote:
Originally Posted by Myself
(watch out for movies though... if using an LT'd, non highpassed sub for movies at higher SPLs, you could easily damage a driver).
In 2 cu ft and a 500w amp, this won't actually be a problem. The amp will clip before the driver can move mechanically far enough to damage itself. No high pass filter is necessary in this case. A room-tailored linkwitz transform q = .5 is a sweet idea for music and not a problem for movies either.

In 3 cu ft and a 500w amp, this would be a problem though. The driver becomes more efficient at low frequencies, so the same amount of power, can seriously damage it. the limit of the LT circuit's boost is the amplifier, but the limit of the system is the driver's throw.

Finally, I want to say that you DO need capable mains to blend to a sub without a crossover. A sub is not a replacement for a main - it is an augmentation to help improve headroom as well as smooth out in room frequency response. You can normally get VERY flat response over a wide range of seats by implementing multiple sources of bass.

mains don't however need to extend down to 20hz. In fact that will compromise their sensitivity and as a consequence, their dynamic ability. Every room has different mode frequencies but generally if your mains can hit 60 to 100hz at meaningful SPLS you're good.

Now meaningful SPLs at these frequencies can be very high. 100hz to 400hz is a big power region. So a BIG main is NOT a bad idea - but focus more on sensitivity in that upper bass / lower midrange than on depth... let subs handle depth. Wimpy mains are never acceptable and they're of course more important than subs. I can live without subs altogether, but i wouldn't choose to. I can't live with wimpy / or poor / mains.

So if you feel you want to build a new pair of mains, don't feel discouraged.. you can do that too. But the effects multiple subs reintroduce are positive... IMO

Last edited by RockLeeEV; 19th December 2011 at 06:45 PM.
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Old 20th December 2011, 02:03 AM   #123
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Oh my goodness, what an explanation!!! I'm just starting to understand what's going on and the more I understand things the more I discover there's more things to understand...

Among other things, I just made a basic test based on my room depth that's 12.8'... The calculated axial first-order resonance frequency perpendicular to the speaker is 44HZ. Using a signal generator at this frequency permit confirmation of this as there's a "hole of silence" right at the middle of the room. I feel like a baby that walks for the first time... D'UH.

Martin.
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Old 21st December 2011, 12:15 AM   #124
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For anyone interrested, a good writing on the matter: Red Spade Audio: A basic guide to bass bliss
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Old 21st December 2011, 12:56 AM   #125
pski is offline pski  United States
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Years (decades) ago, I had nearly bi-polar speakers that were very acceptable when placed correctly. As before a small distance seems to make a lot of sense.

The Red Spade article seems to indicate a lot of toe-in. Is that correct in y'all's experience?

I'm tuning some home made kits at this point and really need to remove the other speakers in the room but right now they are slightly toed and 39" from the rear walls and about 4' from the sides. Since they are back ported, I could be convinced the "open baffle" diagram is good but I'd hope for help in this issue.

P
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Old 21st December 2011, 02:42 AM   #126
AllenB is offline AllenB  Australia
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Although this is quite dependent on the speaker design, I don't typically consider that there is much of a good reason to listen to a speaker on-axis and I feel it is done too often by default. The angle you listen on should not be some random angle either. In my case I listen at around 20 degrees (relative to my listening position).
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Old 21st December 2011, 08:45 PM   #127
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Interesting thread.
For me no box speaker or narrow baffle design will do. Neither will a radiating cone.
What you really want to hear is front loaded horn bass down to say 100 or 90Hz and from there down a pair of tapped horns. Yes they are a little large but horns can couple to the air in a way that no radiator can. So you can have fast, deep bass, down to 20Hz and hear say church organs right down as low as any playback system can.

I had never heard a pair of tapped horns and it was unlikely I would so I built a pair for my then 4 way system. Nothing like them. Natural unaffected, deep and easy to listen to, realistic and there's two of them. I use 2 15" Eminence Kappas for the mid bass front loaded horns and two 15" Eminence Kappa LFII's for the tapped horns.
If you can then I would build a couple of them and get them integrated nicely (it was a bit of a challenge for my room - positioning and amplification needed tweaking as well as crossovers). But I am happy with the result and love what they do.

Do consider tapped horns!

Last edited by Speedysteve7; 21st December 2011 at 08:48 PM.
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Old 21st December 2011, 11:47 PM   #128
pski is offline pski  United States
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Quote:
Originally Posted by Speedysteve7 View Post
Interesting thread.
For me no box speaker or narrow baffle design will do. Neither will a radiating cone.
What you really want to hear is front loaded horn bass down to say 100 or 90Hz and from there down a pair of tapped horns. Yes they are a little large but horns can couple to the air in a way that no radiator can. So you can have fast, deep bass, down to 20Hz and hear say church organs right down as low as any playback system can.

I had never heard a pair of tapped horns and it was unlikely I would so I built a pair for my then 4 way system. Nothing like them. Natural unaffected, deep and easy to listen to, realistic and there's two of them. I use 2 15" Eminence Kappas for the mid bass front loaded horns and two 15" Eminence Kappa LFII's for the tapped horns.
If you can then I would build a couple of them and get them integrated nicely (it was a bit of a challenge for my room - positioning and amplification needed tweaking as well as crossovers). But I am happy with the result and love what they do.

Do consider tapped horns!
A convenient place for you to explain "tapped horns" and what they do and don't do. Never heard of this myself.

P
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Old 22nd December 2011, 08:55 AM   #129
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Ooh yes.
They are the wardrobes down the sides of my horns in my avatar.

Here's where I got my inspiration form

Tapped Horn Experiments

and another epic thread on DIYaudio I can't find right now.

and here is my own thread about horn all the way to 5 way on this site.

5 way project - tapped, bass, mids and tweeter, big boy system

If you have the space and I found firing one left to right and the other down the room worked really well and better than in the early measurements I took
they can go in the corners and get corner loading. Having one amp per speaker pair is essential I think.



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Originally Posted by pski View Post
A convenient place for you to explain "tapped horns" and what they do and don't do. Never heard of this myself.

P
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Old 22nd December 2011, 01:09 PM   #130
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I've found a thread worth reading to help solve my bass problem... Multiple Small Subs - Geddes Approach

From what I've learned through this tread and elsewhere, "no sub = no bass" is untrue. But poor room = bad bass response = TRUE.

High-level steps seems to be, in this order:
#1- Work the room first, identify modal problems and try reducing reflexions;
#2- Distribute bass sources, up to 3 even 4 subs may be required;
#3- If dips and peaks are still too proemininent, fine tune with an Eq;
#4- Do all of this with measurement instruments;
#5- At the end, (globally) adjust to taste.
#6- Sit, listen, enjoy, FEEL the music
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