1 sub, 1000 questions - placement and so on

[anm]

Hi everyone - I am starting this thread to keep all my questions in one place regarding subwoofer placement etc. Every night there is one question that pops up in my head.

Q1 - can I place a bookshelf speaker on top of a subwoofer? Or may be a plant. How to prevent the subwoofer, and stuff on top of it from "walking" and rattling?

Q2 - practically, is it a better idea to use plate amps, or a separate sub amp in the equipment rack? With sub throwing out so much of energy, will it rattle the plate amp and loosen up parts on the plate in a few months?

 

[koushik]

Q1 - can I place a bookshelf speaker on top of a subwoofer? Or may be a plant. How to prevent the subwoofer, and stuff on top of it from "walking" and rattling?

Ans 1) Use anti-skid rubber on the top of the subwoofer. You can find one here. Although, IMO it is better not to keep anything on the subwoofer as the rattling and vibrating sound may add to the distortion.

 

[Flash]

Hi everyone - I am starting this thread to keep all my questions in one place regarding subwoofer placement etc. Every night there is one question that pops up in my head.

Q1 - can I place a bookshelf speaker on top of a subwoofer? Or may be a plant. How to prevent the subwoofer, and stuff on top of it from "walking" and rattling?

Preferably no... if the sub cabinet is resonance free. the bookshelf will not move around. Plus you can add rubber feet on the BS. However preferably nothing on top of the SUB

Q2 - practically, is it a better idea to use plate amps, or a separate sub amp in the equipment rack? With sub throwing out so much of energy, will it rattle the plate amp and loosen up parts on the plate in a few months?

Well it purely depends on user tastes etc etc. Again a plate amp in a properly build subwoofer will never rattle . if you are building one yourself . Use a rubber gasket before fixing the plate amp.
Using a separate monoblock amp to drive the subwoofer would also involve getting a active crossover unless the amp has it. But then again I don''t the need unless a person wants to build 2 passive subwoofers driven by a single monoblock or 2 channel power amp

 

[Vijay_s]

Years back I asked similar question here on placing a sub-woofer on top of other. I got literally killed. :lol:


So in summary : Do not keep anything on top of Subwoofer...

 

[anm]

thanks Flash. Right now I have 2 passive 10" subs, that I am driving with my stereo amp (NAD C375). Since this amp is an overkill, a dedicated subwoofer amp may be a better options.
OTOH, I am waiting for my GR Research sub, but it is getting VERY delayed.
So not sure whether to sit tight and not do anything, vs spend money on a sub amp, and free up C375 for stereo duty, or maybe sell off to create some funds.

Further on Q2 - are there any good sub amps in the market, that have features of a sub amp, like high pass, low pass, equalization?

 

[anm]

On Q1 - I have seen some designs on web where the speaker system is split in two parts - sub and mid+hf. The mid+hf unit placed on top of the sub. What is the best way? Do we also need to use some spikes to reject vibrations from the sub?

 

[cmsajith]

A well build sub will never rattle. Vibration of the sub itself is a misunderstanding, you should not feel much vibrtaion on the surface of the sub if it is well built. Moreover the plateamps will normally have an enclosure to protect all the parts from shaking from the air pressure inside the box, most of the components will be glued to the pcb or some surface nearby.

You can either place the amp outside the box or in a sub enclosure inside the sub so that the air pressure will not come to the amp or directly. The third option requires a tight rubber seal for the best performance of the sub.

 

[cmsajith]

Years back I asked similar question here on placing a sub-woofer on top of other. I got literally killed. :lol:


So in summary : Do not keep anything on top of Subwoofer...

stacking of subs is possible provided it has enough mass to withstand the vibration due to air pressure. Stacking is recommended esp for horn subs.

People may have different opinions, but its not true that it will always be correct.

 

[Flash]

thanks Flash. Right now I have 2 passive 10" subs, that I am driving with my stereo amp (NAD C375). Since this amp is an overkill, a dedicated subwoofer amp may be a better options.

how do you manage the crossover to integrate the roll off of the Bookshelves with the Subwoofer. A dedicated power amp would be better and you can use your NAD to better use.
Cost effective solution is look at PA amps and a Active crossover from Behringer.

OTOH, I am waiting for my GR Research sub, but it is getting VERY delayed.
So not sure whether to sit tight and not do anything, vs spend money on a sub amp, and free up C375 for stereo duty, or maybe sell off to create some funds.

I guess Isaw one of your posts in another thread that you almost clicked on the buy button for the JBLES250PW.( i guess it was you) I refrained from commenting . However It would have been the huge mistake, you can compare the GR servo subs with the JBL . its like comparing your NAD to a Norge 2060.

I would say wait .. its well worth it even if it take 4 months more.

Further on Q2 - are there any good sub amps in the market, that have features of a sub amp, like high pass, low pass, equalization?

well not many. usually in this case . folks buy a PA and a active crossover

 

[anm]

thanks everyone.
Thanks Flash, that was indeed me. Any suggestion on power amp for subwoofers?

 

[anm]

Q3 - converting sealed subs to ported. I am thinking of converting my pair of sealed boxes with 10" eminence Eminence Hl10a 10" Subwoofer 8 Ohm 290-572
Size is slightly greater than 1x1x1ft.
When trying this site Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators for port length calculation, I realized that narrower the port diameter, smaller is the length required. This is too good to be true - as I have less space on front baffle for the port, and can't go much long in the port.
How to decide on length and width of the port? Will smaller port sound noisy?

 

[anm]

need help in converting sealed to ported

 

[Flash]

Step -I

Does it make sense to convert your Eminence sub to Ported .

The T/S parameters of the driver which you mentioned are

Power handling: 300 watts RMS
Voice coil diameter: 2.5
Le: 3.51 mH
Impedance: 8 ohms
Re: 5.36 ohms
Magnet weight: 112 oz.
Fs: 32 Hz
Sensitivity: 87.1 dB 1W/1m
Vas: 1.03 cu. ft.
Qms: 9.9
Qes: .29
Qts: .28
Xmax: 11.1 mm

To see if a driver is better suited for ported or sealed enclosure we need to calculate the EBP

Efficiency Bandwidth Product (EBP) = Free Air Resonance (Fs) / Driver Electrical Q (Qes)

In this case

EBP = 32 / .29
So EBP = 110

EBP Recommendation
less than 50 Sealed
50 to 100 Either
more than 100 Ported

Considering the EBP of your Eminence driver is 110 . a Ported enclosure would be better.

Step - II

A ported Enclosure will always be larger than its sealed Equivalent. -
How did you boil down to the dimensions of the enclosure 1x1x1 ?

 

[anm]

I took these woofers along with the boxes from cybervinay. They are larger than 1x1x1 - I think they would be 44cm widex 40 cm high x 40 cm deep (internal volume guessed). There are 2 boxes, each has a single woofer.
Or a little conservative - 40x36x40 cm. We may have to adjust for bracing and filling.

 

[Flash]

I took these woofers along with the boxes from cybervinay. They are larger than 1x1x1 - I think they would be 44cm widex 40 cm high x 40 cm deep (internal volume guessed). There are 2 boxes, each has a single woofer.
Or a little conservative - 40x36x40 cm. We may have to adjust for bracing and filling.

OK so you planning on using the existing cab. I am not too sure how that would work, as a ported enclosure needs to have a larger internal Air volume.

can you put up a pic of the enclosure again - Lets see how we can modify the existing cabinet to make it a vented enclosure without affecting the present bracing / Structural integrity

 

[anm]

ok will take out the woofers to give an internal pic. Front ports seem a little difficult due to availability of space. Bottom ports should be easier to make. However, will bottom port take away the kick from the bass? I want it to be chest hitting base, if you know what I mean.

 

[anm]

Are there any good and cheap subwoofer for a large room, that I can pick for movies for a largish room, while I am waiting for my gr research kit to arrive? I am getting impatient.

JBL ES250 from amazon.de [23-25k]
Canton sub 12 from amazon.de [~50k ouch!]

 

[anm]

Got a response from rythmik - The DS1510 driver is not available. It will be in stock in 6 weeks. Come back to us in 6 weeks to give you the shipping quote.

 

[anm]

any subwoofer suggestions? Anyone having experience with the canton sub 12?

 

[Kittu]

I think the Def tech pro 800 sub on sale is better than JBL and Canton. Not sure if the seller is willing to ship.