Connections
Above is some information from SL about cables.
Generally choose the lowest capacitance cable and size it for the current and length.
The thicker the cable the less resistance it has and increased resistance affects the higher frequencies more due to the filter formed. So in actual fact you can get away with a thinner cable for low frequencies so long as you keep within it's current rating.
As long as the length of cable is kept fairly short 1.5mm2 should work well enough for everything. I usually go for 2 or 2.5mm2 unless it won't fit in the connector.
I like speakon terminals myself. Very secure, easy to connect, low contact resistance high current and not too expensive. You can solder the wires internally or use 4.3mm quick connects. I like the uninsulated crimp connects as they make good contact with the wire and a blob of solder can be added if needed. Heatshrink on the top makes it secure and safe. Crimping pliers can be bought from most auto parts stores.
I prefer to use a quick connect over soldering the drivers directly. It makes the inevitable change of mind or servicing easier.
Above is some information from SL about cables.
Generally choose the lowest capacitance cable and size it for the current and length.
The thicker the cable the less resistance it has and increased resistance affects the higher frequencies more due to the filter formed. So in actual fact you can get away with a thinner cable for low frequencies so long as you keep within it's current rating.
As long as the length of cable is kept fairly short 1.5mm2 should work well enough for everything. I usually go for 2 or 2.5mm2 unless it won't fit in the connector.
I like speakon terminals myself. Very secure, easy to connect, low contact resistance high current and not too expensive. You can solder the wires internally or use 4.3mm quick connects. I like the uninsulated crimp connects as they make good contact with the wire and a blob of solder can be added if needed. Heatshrink on the top makes it secure and safe. Crimping pliers can be bought from most auto parts stores.
I prefer to use a quick connect over soldering the drivers directly. It makes the inevitable change of mind or servicing easier.
Great! I will use speakon terminals and Sommer Meridian Mobile SP225 cable. The cable has a capacitance of 137 or 150pF per m (depending on 1,5 or 2,5mm²). I hope that's okay because Cordial doesn't even show how much their cable has. Regarding the thickness I will do some more research. I used a cable calculator and it tells me to use 2,5mm² for the subs with a cable length of 8m. I guess 8m are not fairly short anymore but I want to have them a little bit longer so I don't need new cables if I switch to a bigger room.
@fluid you mentioned the low density fiberglass for stuffing. Can you provide a link where I can see a picture of it or a specific product. I'm not sure if it's the same used for glass fiber reinforced plastic. They look very thin.
For polyester there are different products available like from Visaton or this.
By the way my DSP is working
Just need a proper case. Next step is ordering the drivers and building the boxes for the subs and midrange.
@fluid you mentioned the low density fiberglass for stuffing. Can you provide a link where I can see a picture of it or a specific product. I'm not sure if it's the same used for glass fiber reinforced plastic. They look very thin.
For polyester there are different products available like from Visaton or this.
By the way my DSP is working
Just need a proper case. Next step is ordering the drivers and building the boxes for the subs and midrange.It is the insulation used for walls and ceilings in homes you would be able to buy it from any building supply or hardware store.
I used Earthwool from Knauf because it is available for me and it is not as itchy as the old yellow stuff but still itchy if you handle it with bare hands long enough.
Earthwool Insulation | Make Your Home A Comfort Zone
It comes in various densities usually noted by the R value. The lower density stuff has a lower R value.
I have got some bags of that Visaton Polyester stuff at home. I found it to be next to useless for damping the inside of cabinets.
Wool felt or auto carpet felt combined with the fibreglass makes for a well damped sealed cabinet.
I used Earthwool from Knauf because it is available for me and it is not as itchy as the old yellow stuff but still itchy if you handle it with bare hands long enough.
Earthwool Insulation | Make Your Home A Comfort Zone
It comes in various densities usually noted by the R value. The lower density stuff has a lower R value.
I have got some bags of that Visaton Polyester stuff at home. I found it to be next to useless for damping the inside of cabinets.
Wool felt or auto carpet felt combined with the fibreglass makes for a well damped sealed cabinet.
Thanks. When reading fibreglass I had something different in my mind. There is german Knauf website. They don't have this "Earthwool" but different kind of glass wool with different densities. Something like this should work right? Of course Knauf is just an example. I'll check other brands maybe they have even lower density.
Am I right thinking that there is no difference between using more layers of 40mm sheets instead of less layers with thicker material? What's easier to work with? You said heavy stuffing is needed. Does that mean I press as much as possible in the box? Or do I fill it loosely until the box is full? Pressing the material would change the density I guess but I ask to be safe. Sometimes little details make a huge difference.
Am I right thinking that there is no difference between using more layers of 40mm sheets instead of less layers with thicker material? What's easier to work with? You said heavy stuffing is needed. Does that mean I press as much as possible in the box? Or do I fill it loosely until the box is full? Pressing the material would change the density I guess but I ask to be safe. Sometimes little details make a huge difference.
That is the same stuff, I think it is all made in Turkey anyway.
The density isn't critical but the very high density stuff does not work as well for this purpose. Using more lower density works better in most cases.
I line the inside of the cabinet with felt then put the fibreglass in then another layer of felt to keep the fibreglass away from the driver.
I would not try and stuff as much in as you can. That will increase the density and there is definite point where a box can be considered overstuffed.
I chose the point based on measured impedance of the driver in the box. When the small lumps and bumps have been mostly removed and the impedance more closely resembles the free air impedance then it is done. Going too far will cause the impedance peak to be deformed and odd looking.
There are two reasons to stuff the box, one is to reduce the effects of the rear wave the other is to increase the apparent box volume. Two or three layers of 50 to 70mm thick fibreglass with felt should be enough to deal with the rearwave, if you don't need anymore then that is where I would stop.
The density isn't critical but the very high density stuff does not work as well for this purpose. Using more lower density works better in most cases.
I line the inside of the cabinet with felt then put the fibreglass in then another layer of felt to keep the fibreglass away from the driver.
I would not try and stuff as much in as you can. That will increase the density and there is definite point where a box can be considered overstuffed.
I chose the point based on measured impedance of the driver in the box. When the small lumps and bumps have been mostly removed and the impedance more closely resembles the free air impedance then it is done. Going too far will cause the impedance peak to be deformed and odd looking.
There are two reasons to stuff the box, one is to reduce the effects of the rear wave the other is to increase the apparent box volume. Two or three layers of 50 to 70mm thick fibreglass with felt should be enough to deal with the rearwave, if you don't need anymore then that is where I would stop.
It's been a while but finally there is some progress in this project
Two of the subwoofer cabinets are nearly ready. They are made of two different materials as you can see on the picture. Is it called medium density fiber board in english? Everything is glued and fixed with a lot of screws because the "wood" isn't cut with miter and I had no clamps. I will glue a layer of 4mm plywood when everything is tested and finished. Because it's my first project I didn't want to start with 19mm plywood/multiplex.
The gross volume is about 80L and the net volume should be still more than 70L despite the heavy braces. The cabinets are a little bit bigger than the 50L simulated by fluid. I wanted to achieve a certain height with mids and tweeter so the subs work as stands.
For the stuffing there are some common fibreglass products. But at the moment I am thinking about wood fiber insulation board like Steico Flex. I definitely want to use them for my acoustic absorbers but I'm not sure if should try them in the subs to increase the volume seen by the drivers. I mean it's a closed box and there is no way of getting out but still... It's more sustainable and less critical for health. The density is low (R=1,05 40mm) and the characteristics are comparable to fibreglass. If someone has experience with this type of insulation I'm happy to hear about it. I would like to know if it is durable.
Two of the subwoofer cabinets are nearly ready. They are made of two different materials as you can see on the picture. Is it called medium density fiber board in english? Everything is glued and fixed with a lot of screws because the "wood" isn't cut with miter and I had no clamps. I will glue a layer of 4mm plywood when everything is tested and finished. Because it's my first project I didn't want to start with 19mm plywood/multiplex.
The gross volume is about 80L and the net volume should be still more than 70L despite the heavy braces. The cabinets are a little bit bigger than the 50L simulated by fluid. I wanted to achieve a certain height with mids and tweeter so the subs work as stands.
For the stuffing there are some common fibreglass products. But at the moment I am thinking about wood fiber insulation board like Steico Flex. I definitely want to use them for my acoustic absorbers but I'm not sure if should try them in the subs to increase the volume seen by the drivers. I mean it's a closed box and there is no way of getting out but still... It's more sustainable and less critical for health. The density is low (R=1,05 40mm) and the characteristics are comparable to fibreglass. If someone has experience with this type of insulation I'm happy to hear about it. I would like to know if it is durable.
Attachments
Nice job on your first cabinet
The outer box is Medium Density fibreboard (MDF) the braces are particleboard.
The braces are to add stiffness and they work better if they are made of a stiffer material. Plywood is much stiffer than MDF, hardwood is better. A lesser amount of a stiffer brace can work better than a lot of MDF if put in the right place. Something to consider for future cabinets
Before you glue on the plywood outer I would torque the screw heads down so they don't stick out above the MDF surface.
The outer box is Medium Density fibreboard (MDF) the braces are particleboard.
The braces are to add stiffness and they work better if they are made of a stiffer material. Plywood is much stiffer than MDF, hardwood is better. A lesser amount of a stiffer brace can work better than a lot of MDF if put in the right place. Something to consider for future cabinets
Before you glue on the plywood outer I would torque the screw heads down so they don't stick out above the MDF surface.
Thanks
At least my braces add a lot of weight to the cabinets... But I'll consider plywood for the next two subs. If plywood is stiffer maybe I don't need those horizontal plates with four cut-outs. Connecting the opposite sides with straight narrow boards could be easier. That's the reason I bought materials for only two subs. I knew there would be some little things to improve even when it's just for easier workflow.
The screws are still a mystery to me. On the back they went in flat pretty easy. But on the side walls and on the top I couldn't get them deep in while glueing them together on the table. But I'll try with more pressure on the ground.
@Fluid, would it be interesting for you to see how the wood fibre insulation works in the subs? Looks like not a lot people tried it. I'm ready to test it so other people can see how it behaves. Only downside is that I won't make measurements with empty cabinets (without insulation) because the wood fibres are not that flexible and it will be a pain to get it in/out of box after the front is mounted. Worst case would be to take the wood fibres out and add fibreglass afterwards. But if nobody is interested in this material anyway I leaning towards fibreglass to be safe about the expected effect. I'm a little bit afraid that the wood fibre insulation will be wood dust after two years of heavy pressure from the low frequencies.
At least my braces add a lot of weight to the cabinets... But I'll consider plywood for the next two subs. If plywood is stiffer maybe I don't need those horizontal plates with four cut-outs. Connecting the opposite sides with straight narrow boards could be easier. That's the reason I bought materials for only two subs. I knew there would be some little things to improve even when it's just for easier workflow.
The screws are still a mystery to me. On the back they went in flat pretty easy. But on the side walls and on the top I couldn't get them deep in while glueing them together on the table. But I'll try with more pressure on the ground.
@Fluid, would it be interesting for you to see how the wood fibre insulation works in the subs? Looks like not a lot people tried it. I'm ready to test it so other people can see how it behaves. Only downside is that I won't make measurements with empty cabinets (without insulation) because the wood fibres are not that flexible and it will be a pain to get it in/out of box after the front is mounted. Worst case would be to take the wood fibres out and add fibreglass afterwards. But if nobody is interested in this material anyway I leaning towards fibreglass to be safe about the expected effect. I'm a little bit afraid that the wood fibre insulation will be wood dust after two years of heavy pressure from the low frequencies.
Hi guys
I just wanted to thank everybody involved in this thread. The speakers are nearly finished. They need a little bit of work to get a nice look. But I had the chance to hear them some days with two subs. I made just a quick crossover by ear with LR36 at 1100Hz. There are still a lot of measurements to do. But I like the sound very much. So I know the final speaker will sound even better. My impression is that they work well in the corners of my room. It sounds very clear, detailed and precise. You can locate the position of the instruments very well. Someone called it 3D like. The bass is another story. There is work to be done to get it right. But the subs are pretty loud without getting much power from the amp. Guess there is a lot of roomgain.
Btw I chose the wood fibre insulation and filled nearly the entire box. There is no unwanted sound coming from the subs or midspeakers (still need to test at higher volumes). So it works as insulation I guess. But I don't know if it helps to increase the volume seen by the driver. I will make some tests and impedance measurements when everything is ready.
Special thanks goes to krivium who helped me a lot choosing the right speaker type and fluid who was very patient and helped me with my technical questions
I just wanted to thank everybody involved in this thread. The speakers are nearly finished. They need a little bit of work to get a nice look. But I had the chance to hear them some days with two subs. I made just a quick crossover by ear with LR36 at 1100Hz. There are still a lot of measurements to do. But I like the sound very much. So I know the final speaker will sound even better. My impression is that they work well in the corners of my room. It sounds very clear, detailed and precise. You can locate the position of the instruments very well. Someone called it 3D like. The bass is another story. There is work to be done to get it right. But the subs are pretty loud without getting much power from the amp. Guess there is a lot of roomgain.
Btw I chose the wood fibre insulation and filled nearly the entire box. There is no unwanted sound coming from the subs or midspeakers (still need to test at higher volumes). So it works as insulation I guess. But I don't know if it helps to increase the volume seen by the driver. I will make some tests and impedance measurements when everything is ready.
Special thanks goes to krivium who helped me a lot choosing the right speaker type and fluid who was very patient and helped me with my technical questions
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