So it's like this..
I built a pair of speakers a while back..
It was a project started in the late 80s, but shelved midstream because I didn't like the results...
After having thought through a redesign, ordering many of it's parts, and tripping over the cabinets in storage for years....
I decided to commit the time and resources to complete them.
All I had needed was crossovers.... to finish thinking through their design etc..
The woofers I had for them somehow went missing over the years.. so new ones had to be sourced.
The enclosures were ported.... the woofers had to be more of a compromise than the lost ones would've been...
Long story short... they came out WAY WAY better than I could've imagined!!!
(one of the great joys of DIY-ing... many failures, but some successes too, and how sweet those are... and the many hours spent listening to them)
They became my main speakers...
Except for ONE flaw....
PORT HONK!
Ironically, the cabinets (and having half the parts) were the main reason for completing these.... but they came out so good, I'd love to build new (acoustic suspension) enclosures for them!!!!
(and of a more nearly ideal size)... but I just don't have the time and funds for that right now..
So I'd like to work with what I have...
The symptom is not THAT bad.... just, compared to how right all the rest is, it really stands out... and annoys......
The bass is clean/fast/deep/articulate and all the other desirable things... BUT for the port artifact..
It presents it self as an "after-event" a split second after the main bass event (sound)... it's a monotone/hollow grunting, that causes a muddy/overhang type of effect.. (at fairly high amplitude).
Previously, I had them in a much larger room... well, a very large room... with a lot of fluffy things in it..
where it was possible to mitigate it... tune it out to a good extent... enough to "listen past" it..
But now, a much smaller room and near field listening is inevitable.
The ports are rear firing, BTW....
So what is the best way to minimize it?
All suggestions would be appreciated!!!
TIA,
Greg
I built a pair of speakers a while back..
It was a project started in the late 80s, but shelved midstream because I didn't like the results...
After having thought through a redesign, ordering many of it's parts, and tripping over the cabinets in storage for years....
I decided to commit the time and resources to complete them.
All I had needed was crossovers.... to finish thinking through their design etc..
The woofers I had for them somehow went missing over the years.. so new ones had to be sourced.
The enclosures were ported.... the woofers had to be more of a compromise than the lost ones would've been...
Long story short... they came out WAY WAY better than I could've imagined!!!
(one of the great joys of DIY-ing... many failures, but some successes too, and how sweet those are... and the many hours spent listening to them)
They became my main speakers...
Except for ONE flaw....
PORT HONK!
Ironically, the cabinets (and having half the parts) were the main reason for completing these.... but they came out so good, I'd love to build new (acoustic suspension) enclosures for them!!!!
(and of a more nearly ideal size)... but I just don't have the time and funds for that right now..
So I'd like to work with what I have...
The symptom is not THAT bad.... just, compared to how right all the rest is, it really stands out... and annoys......
The bass is clean/fast/deep/articulate and all the other desirable things... BUT for the port artifact..
It presents it self as an "after-event" a split second after the main bass event (sound)... it's a monotone/hollow grunting, that causes a muddy/overhang type of effect.. (at fairly high amplitude).
Previously, I had them in a much larger room... well, a very large room... with a lot of fluffy things in it..
where it was possible to mitigate it... tune it out to a good extent... enough to "listen past" it..
But now, a much smaller room and near field listening is inevitable.
The ports are rear firing, BTW....
So what is the best way to minimize it?
All suggestions would be appreciated!!!
TIA,
Greg
Maybe one way is to use an app on your phone. Try analysing sound from the port (or from the speaker generally) to identify particular peaks.
Also worth downloading test tones and frequency sweeps to aid in diagnosing problems.
One simple method might be to stuff poly batting into the port and see if that improves the situation.
Also worth downloading test tones and frequency sweeps to aid in diagnosing problems.
One simple method might be to stuff poly batting into the port and see if that improves the situation.
Best Answer
Most likely for the particular reflex design, a PR should have been used to begin with. WHG
Most likely for the particular reflex design, a PR should have been used to begin with. WHG
Hi and thanks to all for the replies!
Would be nice to tone it down if not eliminate it though....
Tried that particular one though...
It made a change.. not an improvement...... well maybe a little, but I eventually pulled them out.
The woofer is the Hi Vi F-10
Here:
HiVi F10 Woofer-HiVi
T/S parameters are under "specifications" tab on that page.
Qts @ 0.31 is a tad on the high side for a reflex speaker.... I suspect the problem is that.
Port size/length is "correct" for the enclosure/woofer.
Just stuff wads in? Roll up the batt?
I may try the grill-cloth over the port trick next...
That might just do it..
Was wondering about foam too.... foam around the port maybe? all over the backs? In the port?
Little late to implement a PR unfortunately..
Thanks again, and further thoughts appreciated....
I think it's just this...
Would be nice to tone it down if not eliminate it though....
I was hoping for more these types of solutions...
Tried that particular one though...
It made a change.. not an improvement...... well maybe a little, but I eventually pulled them out.
The woofer is the Hi Vi F-10
Here:
HiVi F10 Woofer-HiVi
T/S parameters are under "specifications" tab on that page.
Qts @ 0.31 is a tad on the high side for a reflex speaker.... I suspect the problem is that.
Port size/length is "correct" for the enclosure/woofer.
Wondering about the technique?
Just stuff wads in? Roll up the batt?
I may try the grill-cloth over the port trick next...
That might just do it..
Was wondering about foam too.... foam around the port maybe? all over the backs? In the port?
Little late to implement a PR unfortunately..
Thanks again, and further thoughts appreciated....
You ask for advice but don't share enough info.
Anyway, it's not clear at least for me what the symptoms are. However bad bass on a reflex box can be many different things:
1) reflex box for a driver meant to be used in a closed box - not this case as a 0.31 Qts driver IS a driver designed for a vented box (the Qts will also be somewhat higher depending on the resistance added by cable and coils).
2) bad bass alignment - no info for your case
3) inaccurate or insufficient internal damping - again no info for your case, very dependent on the box geometry
4) vibration, from the box itself or from other loose pieces (terminals, tube, crossover) - as already suggested check with a slow sweep
If you fill the port, then your box is not vented anymore. If the symptoms are the same check for options 3 or 4.
Ralf
Hello,
If you would like a software program that gives some idea of what the variables changing result in, take a look at the program on the following link. Has been a while since I used it, but worked pretty well.
Flare-it - Free Speaker Design Software
Regards,
Greg
If you would like a software program that gives some idea of what the variables changing result in, take a look at the program on the following link. Has been a while since I used it, but worked pretty well.
Flare-it - Free Speaker Design Software
Regards,
Greg
I've heard plenty of people complain about bass Issues with rear ported speakers that are too close to a rear wall. You could experiment with positioning or even move the port to the front.
Something else to consider Is the fact that the crossover Is designed for a different woofer (assuming the HiVi F10 Isn't a suggested drop In replacement for this particular design).
Something else to consider Is the fact that the crossover Is designed for a different woofer (assuming the HiVi F10 Isn't a suggested drop In replacement for this particular design).
You could try (very) loosely stuffing the enclosure with the lightest polyfil batting, as is sold at craft stores for pillows. Defeating the port is not a good idea since you have a driver with limited x-max. It's a horses for courses deal. Personally, as a sealed box/TL guy I would try a 12" PR, since I don't believe ported boxes ever forget what frequency at which they must resonate. Meanwhile the bass line is just walking around all over the place. JMO, YMMV, yadda yadda.
Quote:
Port size/length is "correct" for the enclosure/woofer.
If you provide the following information, it will be much easier to see what's going on:
1. Total cabinet volume (don't subtract driver or port displacement)
2. Port diameter, length, and location (photo will be great)
3. Crossover schematic.
Port size/length is "correct" for the enclosure/woofer.
If you provide the following information, it will be much easier to see what's going on:
1. Total cabinet volume (don't subtract driver or port displacement)
2. Port diameter, length, and location (photo will be great)
3. Crossover schematic.
Cabinet geometry is also important. Read the 2-way enclosure section and look at the images for an example: Zaph|Audio - ZRT - Revelator Tower
Despite its small height, the 140Hz impedance bump is audible.
Ralf
Despite its small height, the 140Hz impedance bump is audible.
Ralf
I'm no great shakes on reflex designs. But an 8" reflex bass is going to be in 30-60L in all likelihood.
There is NO exact correct tuning. Just what works for you and your room and placement near or far away from the wall.
TUNING KLS-9
IMO, if you have too big a box, the bass is going to get flabby and uncontrolled and distorting. Like the guys say, without any idea of the cabinet and port, we might as well use a Ouija Board to divine what is going on.
There is NO exact correct tuning. Just what works for you and your room and placement near or far away from the wall.
TUNING KLS-9
IMO, if you have too big a box, the bass is going to get flabby and uncontrolled and distorting. Like the guys say, without any idea of the cabinet and port, we might as well use a Ouija Board to divine what is going on.
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