Hey guys, thanks for letting me join.
I recently built some partly home made speakers. In reality I used an existing cabinet for some old Sony 2 way speakers and converted them into 3 way speakers with a cross over. One bullet type tweeter, one 3 inch mid sealed back midrange, one 8 inch woof for each cabinet. The cross over is supposedly a 3 way cross over but is really just a 2 way cross over as the woofer is connected directly to the input. Not sure if this is the usual arrangement.
Everything sounds good except for the fact that I'm very disappointed by the bass performance. Initially it was worse, during the first test even though the speakers were loud the bass fell horribly flat. The bass ports were also blowing tons of wind, almost like a fan. Adding a layer of insulating material to the inside of the cabinet helped a lot to my amazement. It cut down on the wind effect and made the bass sound better. It also made the cabinets stop walking around like they were initially, I couldn't keep them put. First I added one layer and then another which improved things further. I did not add more after this point as I figured past this point it would begin muting the sound based on a previous experiment I performed. The cabinets still vibrate and move on the floor a tiny bit but not much.
Regardless of the improvements, the bass is still honestly kind of crap. The bass isn't absent just sounds like there's way too little of it and turning it up further does not help and ends up pushing the other drivers into distortion. Kick drums seem to sound okay but bass lines are barely there. The woofers themselves seem to be working their ***** off but aren't producing much actual sound. If however I go to the corner of my room where my bed is, they sound like what I think they should sound like all the time. If i go back and stand in front of them, again nothing. I know room acoustics play a big role but I feel they should sound a lot better all on their own. Since these cabinets were made for 8 inch woofers to begin with I did not expect there to be a problem with an incorrect cabinet size for these woofers but it seems that this is what is happening.
The cabinets are 55.5cm tall 32.4cm deep and 22.8cm deep. Wood thickness is about 1.3cm. One of my doubts about these cabinets are the ports. They are about 5.4cm in diameter but have no pipe, in other words it's just a hole in the front of the speakers with no port going deep into the cabinet.
I'll admit I used some pretty generic speakers, I know i'll probably lose about half of you there, but the mids and tweeters sound decent. I feel like the woofers despite their cheapness should still be capable of more than what they are doing now. They may be falling a bit flat but the bass isn't totally missing and when I get in that corner of my room they sound amazing. I feel like they are perfectly capable of doing better.
My question would be what is causing this? Perhaps I need to make the port smaller or larger? I tried sealing the port and it doesn't really help. At one point I removed the connector panel at the back for the cross over and having that "port" open gave some very good sounding bass but only if i stood directly behind the speakers. I'm also guessing that the fact that these still walk about the floor a little bit means that these cabinets are still flexing a bit too much and may be wasting energy.
I'd love to hear your suggestions. I'm willing to try some different woofers but I hope I dont end up spending money for something that's still gonna end up sounding crap.
Thanks a lot and I hope to hear back from you!
I recently built some partly home made speakers. In reality I used an existing cabinet for some old Sony 2 way speakers and converted them into 3 way speakers with a cross over. One bullet type tweeter, one 3 inch mid sealed back midrange, one 8 inch woof for each cabinet. The cross over is supposedly a 3 way cross over but is really just a 2 way cross over as the woofer is connected directly to the input. Not sure if this is the usual arrangement.
Everything sounds good except for the fact that I'm very disappointed by the bass performance. Initially it was worse, during the first test even though the speakers were loud the bass fell horribly flat. The bass ports were also blowing tons of wind, almost like a fan. Adding a layer of insulating material to the inside of the cabinet helped a lot to my amazement. It cut down on the wind effect and made the bass sound better. It also made the cabinets stop walking around like they were initially, I couldn't keep them put. First I added one layer and then another which improved things further. I did not add more after this point as I figured past this point it would begin muting the sound based on a previous experiment I performed. The cabinets still vibrate and move on the floor a tiny bit but not much.
Regardless of the improvements, the bass is still honestly kind of crap. The bass isn't absent just sounds like there's way too little of it and turning it up further does not help and ends up pushing the other drivers into distortion. Kick drums seem to sound okay but bass lines are barely there. The woofers themselves seem to be working their ***** off but aren't producing much actual sound. If however I go to the corner of my room where my bed is, they sound like what I think they should sound like all the time. If i go back and stand in front of them, again nothing. I know room acoustics play a big role but I feel they should sound a lot better all on their own. Since these cabinets were made for 8 inch woofers to begin with I did not expect there to be a problem with an incorrect cabinet size for these woofers but it seems that this is what is happening.
The cabinets are 55.5cm tall 32.4cm deep and 22.8cm deep. Wood thickness is about 1.3cm. One of my doubts about these cabinets are the ports. They are about 5.4cm in diameter but have no pipe, in other words it's just a hole in the front of the speakers with no port going deep into the cabinet.
I'll admit I used some pretty generic speakers, I know i'll probably lose about half of you there, but the mids and tweeters sound decent. I feel like the woofers despite their cheapness should still be capable of more than what they are doing now. They may be falling a bit flat but the bass isn't totally missing and when I get in that corner of my room they sound amazing. I feel like they are perfectly capable of doing better.
My question would be what is causing this? Perhaps I need to make the port smaller or larger? I tried sealing the port and it doesn't really help. At one point I removed the connector panel at the back for the cross over and having that "port" open gave some very good sounding bass but only if i stood directly behind the speakers. I'm also guessing that the fact that these still walk about the floor a little bit means that these cabinets are still flexing a bit too much and may be wasting energy.
I'd love to hear your suggestions. I'm willing to try some different woofers but I hope I dont end up spending money for something that's still gonna end up sounding crap.
Thanks a lot and I hope to hear back from you!
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Bass is dominated by room modes. In the corners standing waves will collect and are called room resonance modes. They may sound good to you, but believe me they aren't. As a simple experiment, put the speakers in the corners instead of yourself and see what happens.
Unfortunately I can't put the speakers in the corners due to the way the room is set up. Are you saying that would help or would it more to prove the negative effect the corners have?
I did try experimenting with different speaker placements, placing them in the middle of the room, on the opposite end, placing them further apart, facing them away, etc etc. None of them gave a very satisfactory result. Mostly just the same kind of sound and others eliminate the only little "sweet" spot I have which is to lay on my bed lol.
I did try experimenting with different speaker placements, placing them in the middle of the room, on the opposite end, placing them further apart, facing them away, etc etc. None of them gave a very satisfactory result. Mostly just the same kind of sound and others eliminate the only little "sweet" spot I have which is to lay on my bed lol.
Hmm did my other post not send or am I still under approval?
Anyway I can't place the speakers in the corners due to the way my room is set up. Would that help or do you mean I should try it just to sort of prove the negative effects of the room modes?
I tried experimenting with speaker placement, putting them in the middle of the room, facing them away from me, etc etc but nothing seemed to give as good of a result as what I have now which isn't a good thing.
Anyway I can't place the speakers in the corners due to the way my room is set up. Would that help or do you mean I should try it just to sort of prove the negative effects of the room modes?
I tried experimenting with speaker placement, putting them in the middle of the room, facing them away from me, etc etc but nothing seemed to give as good of a result as what I have now which isn't a good thing.
You cannot throw a random 8" woofer in a ported box built for a completely different 8" woofer and expect it to work unless the t\s parameters matched which is highly unlikely that is why your bass sounds like **** and the speaker moves around and lots of air comes out the port.
Mark
Mark
The boxes are probably tuned too high because the "ports" have a really short effective length. This causes the port to act as an acoustical short circuit at low frequencies - a literal hole in the box. The port and woofers work against each other at low frequencies delivering weak bass in to the room and woofer excursion becomes uncontrolled.
If you are unable to model the woofers/boxes using a program like WinISD or BassBox Pro, try experimentally lengthening the ports by extending them with some tube/pipe.
If you are unable to model the woofers/boxes using a program like WinISD or BassBox Pro, try experimentally lengthening the ports by extending them with some tube/pipe.
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"Wood thickness is about 1.3cm. One of my doubts about these cabinets are the ports. They are about 5.4cm in diameter but have no pipe, in other words it's just a hole in the front of the speakers with no port going deep into the cabinet"
That means "tuning" at around 150Hz. No wonder there is no bass!
25cm port length gives tuning to 33Hz, try that! The test port can be outside and final port tube may have a bend to fit in the enclosure.
That means "tuning" at around 150Hz. No wonder there is no bass!
25cm port length gives tuning to 33Hz, try that! The test port can be outside and final port tube may have a bend to fit in the enclosure.
I made some pipes out of thick construction paper to experiment. At 25cm that definitely helped while listening to a 40hz signal. Cleans up and "rounds up" the sound instead of sounding like speakers that are just flopping around. For now I've installed these semi permanently using a slight bend of the pipe to make em fit.
I have a new problem now however, one of my woofers has started to rattle. What pieces of crap! Rated at 150W using them with an amplifier that's giving them about half that. Of course I realize manufacturers tend to lie but jeez.
So okay looks like i have no choice but to renew my woofers. Considering my cabinet dimensions what would be your recommendations and other cabinet mods I might do to make everything sound better?
I have a new problem now however, one of my woofers has started to rattle. What pieces of crap! Rated at 150W using them with an amplifier that's giving them about half that. Of course I realize manufacturers tend to lie but jeez.
So okay looks like i have no choice but to renew my woofers. Considering my cabinet dimensions what would be your recommendations and other cabinet mods I might do to make everything sound better?
Power testing a driver is actually quite precisely defined below in terms of bass loading, something you evidently wouldn't know from a hole in the ground... 😀
A high efficiency 8" bass is actually unlikely to be comfortable with more than 25W rms.
I know this sort of thing well enough:
That's how it is done. Crossovers matter too. You usually need a coil at least on the bass unit.
A high efficiency 8" bass is actually unlikely to be comfortable with more than 25W rms.
I know this sort of thing well enough:
That's how it is done. Crossovers matter too. You usually need a coil at least on the bass unit.
Attachments
Simple test for baffle step correction(or lack thereof).
Put your speaker boxes back-to-back.
Better bass? You need correction. Too much? You have correction.(try with ports open and closed, your tuning issues could make it hard to hear what's going on)
If you need correction add a coil to the woofer for a start.
Put your speaker boxes back-to-back.
Better bass? You need correction. Too much? You have correction.(try with ports open and closed, your tuning issues could make it hard to hear what's going on)
If you need correction add a coil to the woofer for a start.
1) Your boxes are not made well enough for the power you are putting in. If the boxes are moving all over the place, all your power is going to box flex, and not to the air movement. Your boxes need to be thicker, with more bracing.
2) You need to download WINISD (free), put your driver and box in there, and see what the porting should be. This will tell you if you are even close on your port, or if you need to modify it.
3) put the speaker where the bass sounds good. Just to test the situation, not to find it’s final resting spot.
2) You need to download WINISD (free), put your driver and box in there, and see what the porting should be. This will tell you if you are even close on your port, or if you need to modify it.
3) put the speaker where the bass sounds good. Just to test the situation, not to find it’s final resting spot.
ouch.. okay then.
Anyway, thanks for the input guys. I'll check out winisd, I'll have to run it in virtual box as they have no mac version available.
boswald, I'll perform that test, thanks.
In regards with the excessive power making the cabinet vibrate, I'll downgrade these to work with my smaller technics amp.
Will await some suggestions for good woofer replacements.
You are getting tough love from me, because you have already blown a bass unit as far as I can tell. 😀
I mean, you had nothing stopping the bass hitting the end stops when you wicked it up! The very efficient speaker below has a fairly high reflex tuning, hence the smallish tube:
Even so, I'd be surprised if it has a safe XMax excursion beyond 5mm. You should be cautious with the volume control and bass control. High efficiency equates to poor bass depth. Just how it works.
Replacement woofers come in three types. Qts < 0.38 is reflex. Qts = 0.5 is a closed box driver. Qts >0.7 is a car parcel shelf woofer, which has little use in domestic HiFi.
A masterclass by Troels Gravesen for a good reflex 3-way:
SEAS-3-Way-Classic
I like my two-way closed box speakers. Nothing pricey there.
Nothing too hard in the crossover either:
Welcome to our fun hobby. There's a lot to learn. Nobody gets it right first time.
I mean, you had nothing stopping the bass hitting the end stops when you wicked it up! The very efficient speaker below has a fairly high reflex tuning, hence the smallish tube:
Even so, I'd be surprised if it has a safe XMax excursion beyond 5mm. You should be cautious with the volume control and bass control. High efficiency equates to poor bass depth. Just how it works.
Replacement woofers come in three types. Qts < 0.38 is reflex. Qts = 0.5 is a closed box driver. Qts >0.7 is a car parcel shelf woofer, which has little use in domestic HiFi.
A masterclass by Troels Gravesen for a good reflex 3-way:
SEAS-3-Way-Classic
I like my two-way closed box speakers. Nothing pricey there.
Nothing too hard in the crossover either:
Welcome to our fun hobby. There's a lot to learn. Nobody gets it right first time.
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