Hi guys, I've just purchased some cheap fronts for my HT room which are Energy XL26.
They have two 50mm X 120mm long ports, one on the back and one flared one the front both common to both 6.5" bass drivers.
My question is why do this when they could have had just one bigger one on the front?
My other question because they'er close to the rear wall should I block the rear one, and what will the result be?
Thanks for any help.
Cheers George
They have two 50mm X 120mm long ports, one on the back and one flared one the front both common to both 6.5" bass drivers.
My question is why do this when they could have had just one bigger one on the front?
My other question because they'er close to the rear wall should I block the rear one, and what will the result be?
Thanks for any help.
Cheers George
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Don't know why there are opposing ports other than as a unique selling point.
I do know that blocking a port is useful when a large speaker is used in a small room in order to prevent the bass output from being overwhelming.
I do know that blocking a port is useful when a large speaker is used in a small room in order to prevent the bass output from being overwhelming.
After giving it some thought! 😉
If one port of the combined area of the two ports were used then, in order to maintain the tuning frequency, it would be too long to fit the width of the enclosure.
Blocking one of the ports will change the tuning frequency. Why not try it - it may or may not suit your speaker/room combination.
If one port of the combined area of the two ports were used then, in order to maintain the tuning frequency, it would be too long to fit the width of the enclosure.
Blocking one of the ports will change the tuning frequency. Why not try it - it may or may not suit your speaker/room combination.
I did notice the rear port is staggered to the front port, both are on the horizontal center-line, the rear one is some six inches lower than the front, making the rear port some 12 inches to the floor??? Stuffing one of the two ports will increase the velocity encountered by the remaining open one... & the "tuning" of the enclosure will be "all out of whack"...too "boomy"?, either relocate or dial it back down.
-------------------------------------------------------------------Rick......
-------------------------------------------------------------------Rick......
Correction! One port equal to the combined area of the two ports would be the same length to maintain the tuning frequency.
However, if the tuning frequency requires a long port and the enclosure is not deep enough then it can be replaced by two shorter ports.
However, if the tuning frequency requires a long port and the enclosure is not deep enough then it can be replaced by two shorter ports.
Internal cabinet depth is 300mm, external 340mm, so length wasn't the issue at 240mm for both ports combined into one
Cheers George
Yeah that did cross my mind, but I didn't know the effect, "boomy" is something I wouldn't want. Reduced low end I would have been ok with, and would have compensated for with the the sub.
Cheers George
The owner's manual provides guidance on positioning (page 2).
Energy e:XL-26 Manuals
Ventilation:
Openings in the cabinet are provided for ventilation and to ensure reliable
operation and protect it from overheating so they must not be blocked or
covered . . .
😕
had not considered a need for ventilation, but operation yes.
Energy e:XL-26 Manuals
Ventilation:
Openings in the cabinet are provided for ventilation and to ensure reliable
operation and protect it from overheating so they must not be blocked or
covered . . .
😕
had not considered a need for ventilation, but operation yes.
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Yeah that's why I was asking about blocking the rear port only, I don't mind if it going to reduce how low the bass goes or it output level. But I don't want "boomy" as Richard thinks will be.
Anyone with more port knowledge have a more definitive answer on this?
Cheers George
Anyone with more port knowledge have a more definitive answer on this?
Cheers George
If you decrease the total area of the ports by blocking the rear port then the tuning frequency will decrease.
An incorrectly tuned enclosure will either peak in the bass or slope down in the bass too quickly.
You will be able to tell which applies in your case simply by listening.
True, on all accounts.
And as Richard Ellis pointed out, with just one vent open, the port velocity will increase, which may cause the bass to be boomy, or cause other unwanted noises. Typically, there is a minimum vent "area" that should be used to avoid that. The area of two 50mm vents seems reasonable for dual 6-1/2" woofers.
Easy enough to check. Play some bass material with and without one vent plugged.
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Most likely you'll just lower box FS (tuning frequency) and increase overall "damping" somewhat/IE more relaxed roll off but reach slightly lower frequencies.
I seriously doubt it will introduce any sort of boomy peak.
The tradeoff is that it will probably introduce some port chuffing or turbulence at higher SPL.
I seriously doubt it will introduce any sort of boomy peak.
The tradeoff is that it will probably introduce some port chuffing or turbulence at higher SPL.
Simply put:
A properly tuned enclosure can produce a flat bass response down to the cut-off frequency (f3).
Tuning too high produces a hump in the bass response.
Tuning too low (e.g. if you close the rear port) means the bass will be weak.
It's time for you to put a sock in it - literally! The time honoured way of closing a port is to insert a rolled up pair of socks! 😀
A properly tuned enclosure can produce a flat bass response down to the cut-off frequency (f3).
Tuning too high produces a hump in the bass response.
Tuning too low (e.g. if you close the rear port) means the bass will be weak.
It's time for you to put a sock in it - literally! The time honoured way of closing a port is to insert a rolled up pair of socks! 😀
Not quite true. A port has two lengths, its actual length and its effective length. Its effective length is longer than its actual length due to its end correction (which is 0.6 times the port's radius IIRC). Therefore, a single port having twice the area of the combined areas of two identical smaller ports will need to be a bit shorter than the smaller ports due its larger end correction value.
Paul
Paul
It ain't broke so...
Just try and give it a little breathing room in the back. Doesn't have to be much.
EDIT: they recommend 15" clearance to the wall.
Just try and give it a little breathing room in the back. Doesn't have to be much.
EDIT: they recommend 15" clearance to the wall.
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Thanks for that information Paul. Just for fun, I couldn't resist calculating the difference!
I calculate that the 2 ports each of diameter 50mm could be replaced by a single port of almost exactly 70mm in diameter.
According to your end correction factor that would mean the longer port would have to be about 6mm shorter than the shorter ports.
That is small beer when it comes to the hamfisted way I build speaker cabinets, but could well be significant in terms of tuning frequency!
P.S. Better check my maths as I've already made one mistake on this thread and could be talking rubbish again!
So Galu from what you said above
Your saying if I close the rear port then bass tuning will go even lower??
And also be shelved down in output ("weak" as you put it)?
Cheers George
The bass response will shelve down rapidly but will extend slightly beyond the cut-off frequency of a properly tuned box system.
However, the extended bass will be very low in sound level and may prove little compensation for losing the flat bass response of a properly tuned system.
It is worth experimenting as it may be that in your room you prefer the lower port tuning. When are you going to rummage in your sock drawer George?
However, the extended bass will be very low in sound level and may prove little compensation for losing the flat bass response of a properly tuned system.
It is worth experimenting as it may be that in your room you prefer the lower port tuning. When are you going to rummage in your sock drawer George?
Soon, that will be the last, first I'll get all opinions, and try all the Audyssey configurations, with all ports open, then block the rear one and do all the same again.
Cheers George
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