Light weight cabinet build

[41hzthunder]

Nice job.

I see that a lot of thought and planning went into your design.

I like the way the baffle is recessed in there nicely. Your bracing is interesting.

Every project is a learning experience.

I'm still revising the bracing. It needs reinforcement where the jack plate will be and the handles. Plus plain triangles are overkill. Its better to draw it out a few times than cut wrong once. Just my personal observation based on experience.

 

[TheDuff]

I'm still revising the bracing. It needs reinforcement where the jack plate will be and the handles. Plus plain triangles are overkill. Its better to draw it out a few times than cut wrong once. Just my personal observation based on experience.

Patience and attention to detail are aspects that can add up to a great cumulative outcome.

I definitely want to use a neodymium speaker in my next cabinet. Maybe 15” and compact as possible.

 

[agedhorse]

Patience and attention to detail are aspects that can add up to a great cumulative outcome.

Yet it's easily possible to place so much effort on (unimportant) details that you entirely miss the bigger picture... I see it all the time.

 

[41hzthunder]

I've been distracted for the last week and just getting back to this project. Bassbox is interesting and more robust than WinISD. There's a lot of information in the help too. I now know the driver unloads below box tuning, because the output of the port is out of phase with the driver's forward output. Not sure why its always in phase above tuning, so more to learn. I am also wondering why the program doesn't address standing waves, since it has the internal dimensions of the the box. Seems like it would have been a helpful feature.

When playing with the vents section in the program, the cross section area of the port(s)/vent(s) seem to be more important than the shape. The port length stays the same regardless of port shape, as long as the area remains the same. Putting the vents in the corners looks like an option that could help with the baffle design. However, the grill frame can't interfere with the port/vent. After laying out vents in the corners I realized the issue when trying to figure out the grill attachment. I know, its obvious, all of the parts have to work together. I'm also wondering if using the box sides as part of the vent affects the tuning.

Hoping to start cutting wood by this weekend.

 

[agedhorse]

In general port shape doesn’t matter (within reason). With corner ports, the effective length will be a little longer than the calculated length but generally plenty close enough for most designs.

 

[Wasnex]

Not sure why its always in phase above tuning, so more to learn.

AFAIK, over the active range of the port, the driver and port are not perfectly in phase. This is well over my knowledge level, so someone please correct me if this is too far off the mark.

AFAIK, the port phase response is behind driver phase response--closer to 360 degrees than 0 degrees. The port resonance is initiated by the back of the driver, which is 180 out of phase. Not sure how it's explained, but resulting phase delay of the port is added to this instantaneous 180-degree polarity flip. So in essence, the port response is delayed something like 90 to 180 degrees with a 180 degree polarity flip. This puts the total phase variance between the port and driver somewhere between 270 to 360 degrees. I assume the exact amount of phase variance differs by design and frequency.

 

[agedhorse]

The output from the port is rarely phase.

 

[41hzthunder]

So, I'm guessing in addition to the port reinforcing low end, the sound from it also potentially results in some comb filtering from the phase difference. From what I've read, this is more of an issue for 1) rear ported cabinets and boundary reflections from walls or 2) cabinets with the port some distance from the woofer, affecting mids more than lows. As I understand it, If the port is front facing and closer to the woofer, the two act as a single source (acoustic coupling?) and it is not a significant issue for the low frequencies. This was not how I thought about ports. I had always thought keeping the port further from the woofer would be a priority to keep the pressure from the front and back from cancelling each other. As to the depth of the cabinet affecting phase/comb filtering, it seems cabinet depth is more of a concern for the frequency of the standing waves that can escape from the port.

 

[agedhorse]

Yes there will be some comb filtering, no way to get around it.

 

[41hzthunder]

Finally able to work on measuring T/S parameters and decided to start with the Faital Pro 6FE200, because it has never been out of the box and should be in spec. The free air impedance sweep looked almost identical to the published curve, but the fs reading of 130 was off by 10hz from the published fs of 120. I recalibrated and tested several times and results were the same. I'm wondering if the suspension is stiff because its new and affecting this parameter. Most of the parameters were spot on, or within 1%. I've read that older speakers can go out of spec because the suspension loses some stiffness. I haven't tested the K-140 yet. I'm trying to build confidence in my measurements. What kind of variation should I expect?

 

[agedhorse]

Finally able to work on measuring T/S parameters and decided to start with the Faital Pro 6FE200, because it has never been out of the box and should be in spec. The free air impedance sweep looked almost identical to the published curve, but the fs reading of 130 was off by 10hz from the published fs of 120. I recalibrated and tested several times and results were the same. I'm wondering if the suspension is stiff because its new and affecting this parameter. Most of the parameters were spot on, or within 1%. I've read that older speakers can go out of spec because the suspension loses some stiffness. I haven't tested the K-140 yet. I'm trying to build confidence in my measurements. What kind of variation should I expect?

The tolerance on the published spec is typically +/-10%. Be sure the free air test doesn’t have the speaker sitting on the magnet and that the vent isn’t blocked.

 

[TheDuff]

Finally able to work on measuring T/S parameters and decided to start with the Faital Pro 6FE200, because it has never been out of the box and should be in spec. The free air impedance sweep looked almost identical to the published curve, but the fs reading of 130 was off by 10hz from the published fs of 120. I recalibrated and tested several times and results were the same. I'm wondering if the suspension is stiff because its new and affecting this parameter. Most of the parameters were spot on, or within 1%. I've read that older speakers can go out of spec because the suspension loses some stiffness. I haven't tested the K-140 yet. I'm trying to build confidence in my measurements. What kind of variation should I expect?

It is interesting to see someone that has a good understanding of what they are trying to do.

You seem to understand the theories and principles regarding your speaker design, which I assume is somewhat unique in its parameters.

Secondly in addition to understanding the theories you seem to have the ability to perform parameter measurements with on hand specialized measuring equipment.

Obviously you have developed expertise in this area.

It is interesting to observe you try to figure these things out.

Myself I built my 1st stereo speakers 50 years ago using pine boards and Radio Shack very nice stereo speakers. I think they were 1”x8” two way composite speakers or something of that design model.

I had no idea what I was doing other than common knowledge and decent hand tools, plus some skills and interest.

Those speakers came out far better than anticipated and withstood years of abuse. Never wore out…

Recently I more seriously built 3 bass cabinets of simple sealed compact designs. I researched parameters for simple sealed bass speakers.

During my own construction process I firstly took my time. Didn’t rush. Investigated what I was trying to do. Patience.

I used shiplap pine boards, titebond 3 glue, coated screws, ge silicone sealant, and common sandpaper.

I cut my board pieces carefully with a handheld Dewalt lithium jig saw. Each piece I carefully measured and sanded the ends and edges with my Dewalt lithium palm sander (an awesome tool). I had read that carefully sanding each piece and sharp edges is important and that very many small details are also important.

Measuring of board pieces, accurate calculation of internal volume, accounting for bracing or other considerations. Little things like that often overlooked by casual speaker makers.

I glued and screwed all of my braces. I made the enclosure as rigid as possible, sealing and gaps and all cracks and seams with ge silicone sealant.

I followed the directions and parameters for my simple sealed cabinets closely as they related to the specific speakers that I selected.

It required a lot of time and effort to plan and make these amateurish bass guitar speaker cabinets.

I carefully attached the speaker to the back of the lapboard baffles and applied excellent Mojotown red and black highly durable grill cloth, recessed.

Jack plates, soldered connections, things like that.

I paid close attention to my internal volume calculations and tried to keep my design as close as possible to the desired internal volume. That seemed to be the main factor that I would need to observe and keep close to the target value.

For my use I purchased bass speakers that I didn’t have experience with but wanted to check out. I made 3 cabinets in about a 4 week period last summer.

I used first a Celestion Pulse 10” 8 ohm bass speakers; second cabinet used a Celestion Pulse XL 12” 8 ohm speaker (excellent); and finally I made a cabinet with an Eminence Ca154 4 ohm 15” bass speaker (superior performance).

In addition all 3 cabinets include a very useful innovation of my own design. I made 4 square corner posts from strips of pressure treated 1” deck board. These square corner posts are located at each corner/side of the cabinet and extend up and down along the corners of the cabinet. Extending 2 inches below each corner and serving as short legs elevating the cabinet above the surface by 2”. Additionally the 1” square corner posts extend 5 inches above each corner proiding 4 super convenient grab handles. These cabs are light. Next time I will use a neodymium speaker.

My results exceeded my expectations in terms of sound quality. The 10” Pulse has expected limitations when pushed hard but otherwise great sound and performance. The 12” Pulse XL is a much better sounding single speaker. It has zero limitations when pushed hard in my playing environment. The 15” Eminence Ca154 is clearly the most superior of the single speaker cabinets. Very excellent sound and tone. No limitations. The cabinet is only very slightly larger than the 1x12 and it too is light.

When moving these cabinets around from room to room the square post grab handles that stick up 5” at each corner are a delight to use. Grabbing the upright corner grab posts is a feature that further makes the light compact cabinets more easily portable.

I’m 76 years old. Portability is important to me and ease of use.

Your project is interesting to me and observing your expertise and patience is something I am learning from.

I will probably never understand exactly how to do it but I can find plans and follow directions. That was my strategy. Use the knowledge found in good plans and speaker parameters. I can find all of that and apply the ideas. I took my time and kept as close as possible to my desired parameter measurements.

I found out that my outcome is not exact but very close to the desired internal volume. Some bracing I might not have anticipated, things like that.

Another thing: when calculating internal volume all internal bracing and other obstructions must be considered and calculated to determine closeness to this desired internal volume. Obviously great attention is paid to calculating this value.

With this in mind you will notice that the back of the speaker extends semi conically into the center of the speaker cabinet, ending its protrusion at the magnet. It sticks back into the middle of the cabinet. Obviously the intrusion of the back of the speaker into the area of the internal volume exists.

Question: Does the area occupied by the back of the speaker itself that extends back into the inside of the cabinet need to be added to the desired total speaker internal volume. That might be difficult to understand. I’m not sure how to explain my concern.

In other words, if the speaker was mounted flush like a piece of paper it would not extend back into the cabinet, obviously. But the speakers mechanical parts extend well into the cabinet internal area. Does this displaced area occupied by the speaker body need to be added to cabinet internal volume. Or does internal volume calculation provided allow for this displacement of the speaker body itself?

I’m not sure about that aspect.

My speakers sound good at home. I’m glad about that. But I’m interested in doing it better next time.

 

[41hzthunder]

It is interesting to see someone that has a good understanding of what they are trying to do.

You seem to understand the theories and principles regarding your speaker design, which I assume is somewhat unique in its parameters.

Secondly in addition to understanding the theories you seem to have the ability to perform parameter measurements with on hand specialized measuring equipment.

Obviously you have developed expertise in this area.

It is interesting to observe you try to figure these things out.

Myself I built my 1st stereo speakers 50 years ago using pine boards and Radio Shack very nice stereo speakers. I think they were 1”x8” two way composite speakers or something of that design model.

I had no idea what I was doing other than common knowledge and decent hand tools, plus some skills and interest.

Those speakers came out far better than anticipated and withstood years of abuse. Never wore out…

Recently I more seriously built 3 bass cabinets of simple sealed compact designs. I researched parameters for simple sealed bass speakers.

During my own construction process I firstly took my time. Didn’t rush. Investigated what I was trying to do. Patience.

I used shiplap pine boards, titebond 3 glue, coated screws, ge silicone sealant, and common sandpaper.

I cut my board pieces carefully with a handheld Dewalt lithium jig saw. Each piece I carefully measured and sanded the ends and edges with my Dewalt lithium palm sander (an awesome tool). I had read that carefully sanding each piece and sharp edges is important and that very many small details are also important.

Measuring of board pieces, accurate calculation of internal volume, accounting for bracing or other considerations. Little things like that often overlooked by casual speaker makers.

I glued and screwed all of my braces. I made the enclosure as rigid as possible, sealing and gaps and all cracks and seams with ge silicone sealant.

I followed the directions and parameters for my simple sealed cabinets closely as they related to the specific speakers that I selected.

It required a lot of time and effort to plan and make these amateurish bass guitar speaker cabinets.

I carefully attached the speaker to the back of the lapboard baffles and applied excellent Mojotown red and black highly durable grill cloth, recessed.

Jack plates, soldered connections, things like that.

I paid close attention to my internal volume calculations and tried to keep my design as close as possible to the desired internal volume. That seemed to be the main factor that I would need to observe and keep close to the target value.

For my use I purchased bass speakers that I didn’t have experience with but wanted to check out. I made 3 cabinets in about a 4 week period last summer.

I used first a Celestion Pulse 10” 8 ohm bass speakers; second cabinet used a Celestion Pulse XL 12” 8 ohm speaker (excellent); and finally I made a cabinet with an Eminence Ca154 4 ohm 15” bass speaker (superior performance).

In addition all 3 cabinets include a very useful innovation of my own design. I made 4 square corner posts from strips of pressure treated 1” deck board. These square corner posts are located at each corner/side of the cabinet and extend up and down along the corners of the cabinet. Extending 2 inches below each corner and serving as short legs elevating the cabinet above the surface by 2”. Additionally the 1” square corner posts extend 5 inches above each corner proiding 4 super convenient grab handles. These cabs are light. Next time I will use a neodymium speaker.

My results exceeded my expectations in terms of sound quality. The 10” Pulse has expected limitations when pushed hard but otherwise great sound and performance. The 12” Pulse XL is a much better sounding single speaker. It has zero limitations when pushed hard in my playing environment. The 15” Eminence Ca154 is clearly the most superior of the single speaker cabinets. Very excellent sound and tone. No limitations. The cabinet is only very slightly larger than the 1x12 and it too is light.

When moving these cabinets around from room to room the square post grab handles that stick up 5” at each corner are a delight to use. Grabbing the upright corner grab posts is a feature that further makes the light compact cabinets more easily portable.

I’m 76 years old. Portability is important to me and ease of use.

Your project is interesting to me and observing your expertise and patience is something I am learning from.

I will probably never understand exactly how to do it but I can find plans and follow directions. That was my strategy. Use the knowledge found in good plans and speaker parameters. I can find all of that and apply the ideas. I took my time and kept as close as possible to my desired parameter measurements.

I found out that my outcome is not exact but very close to the desired internal volume. Some bracing I might not have anticipated, things like that.

Another thing: when calculating internal volume all internal bracing and other obstructions must be considered and calculated to determine closeness to this desired internal volume. Obviously great attention is paid to calculating this value.

With this in mind you will notice that the back of the speaker extends semi conically into the center of the speaker cabinet, ending its protrusion at the magnet. It sticks back into the middle of the cabinet. Obviously the intrusion of the back of the speaker into the area of the internal volume exists.

Question: Does the area occupied by the back of the speaker itself that extends back into the inside of the cabinet need to be added to the desired total speaker internal volume. That might be difficult to understand. I’m not sure how to explain my concern.

In other words, if the speaker was mounted flush like a piece of paper it would not extend back into the cabinet, obviously. But the speakers mechanical parts extend well into the cabinet internal area. Does this displaced area occupied by the speaker body need to be added to cabinet internal volume. Or does internal volume calculation provided allow for this displacement of the speaker body itself?

I’m not sure about that aspect.

My speakers sound good at home. I’m glad about that. But I’m interested in doing it better next time.

To answer your question, yes the driver displacement should be deducted from the internal volume. Bassbox does have a calculator for this and I've seen some online calculators. Some manufacturers publish the displacement. Seems like the mounting, flush or rear, would affect this.

Sounds like you've enjoyed the journey a lot. There are a lot of details involved, almost too many to keep suspended in my mind at once. LOL It sounds like you might have been playing bass and building cabinets for a while. I'm 65 and remember playing in the mid to late 70's. Yeah, playing in bars when I was 15! I tried to learn about cabinet design back then, but there were fewer resources and they were harder to find. I remember JBL published volume and port suggestions, as they supported DIY more at that time. So they must have done the calculations or experimented. I kind of picture a bunch of guys with white shirts with sliderules. The rule of thumb was brace, make it big and heavy, then brace some more. Even when I was 10 I had a lot of curiousity and read about bass reflex, folded horns and infinite baffle designs. I remember one theory that placed a folded horn in a corner and used the walls to extend the horn and develop lower frequency waves. I think I got hooked on music when my dad put Les Paul's How High the Moon on. As far as cabinet building, it was sort of black box and voodoo at some point. In my second or third band, the drummer was into building PA cabinets, folded horns with Gauss drivers and Voice of the Theater designs with Altec drivers. At some point I started to notice limitations and unpleasant resonances in the aluminum 811 horns.

For me, this project is first about producing a good cabinet with the components I have, but also about connecting the theory and practical application. So, in part, it is the journey. I don't rule out the possibility that I will go out and buy a cabinet in the future, but I will be a more informed consumer with a better idea of what I'm looking for. I'm really still just a 15 year-old with more expensive tools now.

 

[41hzthunder]

I was able to work on t/s parameters on the driver today and found a surprise. While attaching the leads to the driver the sunlight from the window hit the back of the cone behind the frame and near the spider. I saw a white number. Moving the driver a bit the number would be lost in glare and come back. I realized its the stamped cone identifier, 52254. I think this is a JBL number and might be for the K-140 cone. Maybe Aged Horse would know.

When I ran the sweeps on the driver, the Fs is 30 hz and the Q values were higher. Seemed a little too high for the Q parameters. However, when adding mass to the cone, I used small neo magnets. After completing multiple sweeps, I removed the magnets and was playing with the magnets like a kid. I was trying to see how far apart they had to be before they wouldn't snap together. It was about 3", which seemed cool. Then it dawned on me that they would have been interacting with the driver motor and probably alter the results. I'll have to find another way to add mass without damaging the cone and repeat the tests.

I'm planning to start building on Saturday. I should have all the parameters and run it through Bassbox by tomorrow night.

 

[agedhorse]

I don’t remember and don’t know if I have that level of data since the parts came as a kit from JBL.

 

[41hzthunder]

I don’t remember and don’t know if I have that level of data since the parts came as a kit from JBL.

I guess this issue came up in another thread last week. A member Flatwound had two K140's one stamped 52254 and the other 76076. He seemed to think the 52254 was a K cone and the 76076 was E. There's no information on how he came to that conclusion. I'll ask him.

 

[TheDuff]

To answer your question, yes the driver displacement should be deducted from the internal volume. Bassbox does have a calculator for this and I've seen some online calculators. Some manufacturers publish the displacement. Seems like the mounting, flush or rear, would affect this.

Sounds like you've enjoyed the journey a lot. There are a lot of details involved, almost too many to keep suspended in my mind at once. LOL It sounds like you might have been playing bass and building cabinets for a while. I'm 65 and remember playing in the mid to late 70's. Yeah, playing in bars when I was 15! I tried to learn about cabinet design back then, but there were fewer resources and they were harder to find. I remember JBL published volume and port suggestions, as they supported DIY more at that time. So they must have done the calculations or experimented. I kind of picture a bunch of guys with white shirts with sliderules. The rule of thumb was brace, make it big and heavy, then brace some more. Even when I was 10 I had a lot of curiousity and read about bass reflex, folded horns and infinite baffle designs. I remember one theory that placed a folded horn in a corner and used the walls to extend the horn and develop lower frequency waves. I think I got hooked on music when my dad put Les Paul's How High the Moon on. As far as cabinet building, it was sort of black box and voodoo at some point. In my second or third band, the drummer was into building PA cabinets, folded horns with Gauss drivers and Voice of the Theater designs with Altec drivers. At some point I started to notice limitations and unpleasant resonances in the aluminum 811 horns.

For me, this project is first about producing a good cabinet with the components I have, but also about connecting the theory and practical application. So, in part, it is the journey. I don't rule out the possibility that I will go out and buy a cabinet in the future, but I will be a more informed consumer with a better idea of what I'm looking for. I'm really still just a 15 year-old with more expensive tools now.

Good. That’s great. I’m sure you learned a lot along the way.

My amateur cabinets exceeded my expectations and I think they sound better than the combo amps I own. But I bought 2 nice small bass heads: a Warwick Gnome pocket size 200 watt amp, and a little bigger Hartke Tx350 300 watt amp that has some great advanced controls and is an awesome amp in my opinion.

So, those amps and my effects pedal, Zoom Ms60b+, contribute to the great sound I get out of the cabinets. Nevertheless I believe that maker bias probably enters the perception picture. But if they sounded terrible I would definitely notice it.

 

[6thplanet]

Then it dawned on me that they would have been interacting with the driver motor and probably alter the results. I'll have to find another way to add mass without damaging the cone and repeat the tests.

Definitely don't use magnets. A decent alternative is a roll of masking or duct tape for big drivers. Not a full roll of duct tape, half or 1/4 left. Standard 3/4" masking tape can be full roll or 1/2 used, catch my drift?

 

[41hzthunder]

Good. That’s great. I’m sure you learned a lot along the way.

My amateur cabinets exceeded my expectations and I think they sound better than the combo amps I own. But I bought 2 nice small bass heads: a Warwick Gnome pocket size 200 watt amp, and a little bigger Hartke Tx350 300 watt amp that has some great advanced controls and is an awesome amp in my opinion.

So, those amps and my effects pedal, Zoom Ms60b+, contribute to the great sound I get out of the cabinets. Nevertheless I believe that maker bias probably enters the perception picture. But if they sounded terrible I would definitely notice it.

Yeah, I'm worried I'll have maker bias, but do plan to attempt objective measurements on the result. I'm getting kind of excited about building it this weekend.

 

[41hzthunder]

Definitely don't use magnets. A decent alternative is a roll of masking or duct tape for big drivers. Not a full roll of duct tape, half or 1/4 left. Standard 3/4" masking tape can be full roll or 1/2 used, catch my drift?

So, just placed on the cone? I'm a bit concerned about using anything sticky on the cone.