Speaker cabinet design and construction _ a little rambling and kind request of advice

[gino1961]

Hi to Everyone !
sorry if the issue has been already debated In case please redirect me to the discussion
After listening to some speakers i have come to the conclusion that the way how a speaker cabinet is designed and built plays a major role in the outcoming sound
Me and a friend did in the past an experiment He found some lead sheets used for cars doors and we stuffed them inside a cheap speaker (unfortunately the lead is very toxic)
The sheets were secured to internal sides with glue and some metallic staples
We were surprised by the difference in sound that some 20 euro lead sheet could provide Even amazed
Above all the sound was more out of the box and the bass of piano and cello much more clear and defined
To cut the story short i think that what really holds back the performance of a cheap speaker is its cabinet
I did another experiment I bought for cheap an old pair of KRK little speakers with broken tweeters They have a quite stiff and heavy cabinet

I took the drivers with similar sizes from other cheap speakers with a thin chipboard
I could not believe my ears I am serious
What is your opinion on speaker cabinets ? are their design and construction a little overlooked maybe ?
Thanks a lot and kind regards
gino

 

[MaxwellsEq]

Driver non-linearity and resonances are "louder" than cabinet resonance. When playing signals, most of what you hear is coming from the drivers, and that sound heavily masks direct sound from the cabinet. However, cabinets do "play along" and poorly braced cabinets with insufficient internal damping can add to speaker distortion.

 

[gino1961]

Driver non-linearity and resonances are "louder" than cabinet resonance. When playing signals, most of what you hear is coming from the drivers, and that sound heavily masks direct sound from the cabinet.

Hi thank you very much for your valuable advice If i understand well i was overrating the influence of the cabinets on the speaker's sound ?

However, cabinets do "play along" and poorly braced cabinets with insufficient internal damping can add to speaker distortion.

I see and this surely happens with cheap speakers
So in the end drivers and xovers make the 90% of the final result ? This is very important for me to know because it shifts my interest to drivers selection and xover design
I am a little on DIY and i use to hunt around for drivers and cabinets ... i have a pair of Thiel cs 1.6 without parts in the garage waiting Next project

 

[somebodyelse]

Hi thank you very much for your valuable advice If i understand well i was overrating the influence of the cabinets on the speaker's sound ?

Probably - so long as the cabinet doesn't have any major issues like a strong panel resonance. If you did a sighted test, or without a direct comparison unmodified vs. modified then the difference may just have been confirmation bias. Measurement would show what the mod really did.

I see and this surely happens with cheap speakers
So in the end drivers and xovers make the 90% of the final result ? This is very important for me to know because it shifts my interest to drivers selection and xover design

Good engineering makes 90% of the final result. Kii don't need exotic drivers to get an excellent result, and things we think of as being cheap and nasty may provide all the performance of a more expensive alternative. See for example noaudiophile's LSR308 mod trying to improve the thin injection moulded baffle but making no difference. The mechano23 has inexpensive drivers and simple construction, but performs very well because of good engineering choices.

 

[Thomas_A]

Here is an extensive measurement article.

Dropbox

www.dropbox.com

I would say (based on my experience and measurements) resonances may be audible when being non-linear. But in those cases, it is bracing, CLD and stuffing the cabinets that helps. As discussed in the article.

 

[gino1961]

Probably - so long as the cabinet doesn't have any major issues like a strong panel resonance. If you did a sighted test, or without a direct comparison unmodified vs. modified then the difference may just have been confirmation bias.

Hi again i see Still i was using a list of selected tracks that i usually use for some listening evaluation There was an enhanced feeling of out of the box sound
a speaker that sounds boxy is unacceptable But you could be very right We could not compare the two speakers side by side after mods ... of course

Measurement would show what the mod really did.

No measurements were carried out unfortunately

Good engineering makes 90% of the final result. Kii don't need exotic drivers to get an excellent result, and things we think of as being cheap and nasty may provide all the performance of a more expensive alternative.

I see But i also read that

The Kii THREE speaker weighs 19 kg (40 lbs). This is the weight of a single speaker unit.

they are pretty massive for mide size speakers I think that high mass can make the cabinet less prone to vibrate We add about 15kg of lead to each speaker Final weight about +20kg for a midsize speaker is quite a lot i guess

See for example noaudiophile's LSR308 mod trying to improve the thin injection moulded baffle but making no difference.

I will study this test in depth Because it is exactly what i had in mind i.e. to leave all other panels as they are and focus the front baffle in order to increase its stiffness and mass
It can be done quite easily by adding another thick sheet of wood to the original baffle Metal sheet would be the best because hugely stiff and heavy
a sandwich construction just for the baffle will increase stiffness and mass

The mechano23 has inexpensive drivers and simple construction, but performs very well because of good engineering choices.

i read the article and thank you for the sharing They could be an excellent choice for range about 100-150Hz indeed
just to give some info my ideal concept for a speaker is something like this one below that i heard and loved a lot My dream speaker

 

[gino1961]

Here is an extensive measurement article.

Dropbox

www.dropbox.com

I would say (based on my experience and measurements) resonances may be audible when being non-linear. But in those cases, it is bracing, CLD and stuffing the cabinets that helps. As discussed in the article.

Hi ! thank you very much indeed I will read it with the most interest Hoping to understand the most I am very ignorant in the field
But i have to say one thing I read something about Thiel speakers They dedicate a lot of efforts in the construction of the front baffle
The highest priced models have even a thick aluminum front baffle
This is the reason why when i found a pair of their cheaper model with missing parts i bought them to use as a diy platform
What i am looking for mostly is a clear out of the box sound A sound that cannot located in the speakers Very spatial

 

[somebodyelse]

Hi again i see Still i was using a list of selected tracks that i usually use for some listening evaluation There was an enhanced feeling of out of the box sound
a speaker that sounds boxy is unacceptable But you could be very right We could not compare the two speakers side by side after mods ... of course

I've made the same mistake in the past. Now I would make changes to one channel at a time so I could compare with the original in mono.

 

[gino1961]

I've made the same mistake in the past. Now I would make changes to one channel at a time so I could compare with the original in mono.

Hi thank again for the very precious advice
Lately i have decided to dedicate more time to study loudspeakers design
I bought a nice device from Dayton Audio to get impedance curve and drivers TS parameters
I also bought a calibrated mic to carry out some freq response tests
My main obsession is how to correlate measurements and sound
There must be a way
The labs of speakers manufacturers are fool of instruments
They invest a lot in machines

 

[NotInYourHead]

Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs

This article explores the myths and facts behind loudspeaker cabinet designs in efforts to help distinguish the legitimately well engineered products from the mediocre ones.

www.audioholics.com

This article should serve you well.

 

[Waxx]

what lead does is damp resonances and make them lower in frequencies, so good to clean up a rattling tweeter mid cabinet. In combination with extensive bracing it can help to make a cabinet dead (or maybe better, less resonant). But it need to be studied where to use it and where not to do it fully right. It's indeed a form of CLD.

Those KRK monitors are not that well made, and i heared higher cabinet resonances also. It could be that you had luck and damped them by guessing, but you did guessing when applying them, not based on vibration measurements (how it should be done). I did not do it with the ones i heared as they are not mine (but used by a friend musician/producer in his studio).

But at the end, if you enjoy your speakers more like this, it's all good. That is what matters at the end. But it's not science based like it should, it wass guessing and luck that solved your issue (at least partly).

 

[DVDdoug]

Lately i have decided to dedicate more time to study loudspeakers design
I bought a nice device from Dayton Audio to get impedance curve and drivers TS parameters

Before you build a box, get some speaker design software and plug-in the T-S parameters. WinISD is FREE. It will help you optimize box size and port dimensions for a ported design. It will also help you to decide if a ported or sealed box is better (it depends on the driver parameters and box size) and you can experiment (virtually) with changes before you build anything. (WinISD is ONLY for the woofer/box. It won't help with integrating a crossover and tweeter, etc.)

...Normally, I'd advise playing around with the software before you buy the driver.

And somebody can probably recommend a website about DIY speakers. There are also some good books but I can't recommend one because ones I have are either too old, or I have a "cookbook" where you can build one of the designs in the book. (I never built anything from the cookbook.)

I also bought a calibrated mic to carry out some freq response tests

That should be helpful but usually a calibrated mic is used to make "final EQ tweaks" or to help fix acoustic problems of the speaker and room combined.

You'll probably hear problems before you measure them, but measuring can help with diagnosis and it may help to tweak the crossover to "balance" the woofer and tweeter (and midrange if any) .

I assume you have downloaded REW?

My main obsession is how to correlate measurements and sound
There must be a way
The labs of speakers manufacturers are fool of instruments
They invest a lot in machines

Amir has a YouTube video about speaker measurements. (It runs about an hour.)

Unfortunately, few manufacturers publish detailed measurements and some don't have (and don't rent) the test equipment and/or anechoic chamber.


-----------------------------------------------------------
Back to the lead lining, etc...
Usually I just knock on the cabinet and if it rings/resonates it needs dampening or bracing. And when I build a speaker I usually put fiberglass inside as "standard practice". A small cabinet may not require bracing.

They make adhesive vinyl which is sort-of the same idea as lead, but they say it's "light weight" so I'm not so sure how much it would help with wood. But you wouldn't have to worry about vibrating or rattling.

Stuffing or lining the box with fiberglass (or "less-nasty" speaker stuffing material) usually helps. That will also help with the internal resonances related to dimensions and
wavelengths. (Those wavelengths are not in the bass range.)

 

[Ktacos]

Before you build a box, get some speaker design software and plug-in the T-S parameters. WinISD is FREE. It will help you optimize box size and port dimensions for a ported design. It will also help you to decide if a ported or sealed box is better (it depends on the driver parameters and box size) and you can experiment (virtually) with changes before you build anything. (WinISD is ONLY for the woofer/box. It won't help with integrating a crossover and tweeter, etc.)

I would advise OP use vituix cad for this. It's enclosure tool is much better than winisd and a lot easier to use.

 

[gino1961]

Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs

This article explores the myths and facts behind loudspeaker cabinet designs in efforts to help distinguish the legitimately well engineered products from the mediocre ones.

www.audioholics.com

This article should serve you well.

Hi thanks a lot I will read it with the most interest before starting any modding for sure

 

[gino1961]

what lead does is damp resonances and make them lower in frequencies, so good to clean up a rattling tweeter mid cabinet. In combination with extensive bracing it can help to make a cabinet dead (or maybe better, less resonant). But it need to be studied where to use it and where not to do it fully right. It's indeed a form of CLD.

Those KRK monitors are not that well made, and i heared higher cabinet resonances also. It could be that you had luck and damped them by guessing, but you did guessing when applying them, not based on vibration measurements (how it should be done). I did not do it with the ones i heared as they are not mine (but used by a friend musician/producer in his studio).

But at the end, if you enjoy your speakers more like this, it's all good. That is what matters at the end. But it's not science based like it should, it wass guessing and luck that solved your issue (at least partly).

Thanks a lot again I did some search in the past and actually as you say a cabinet mass increase could be good for mid and high frequencies moving the resonances below the mid cutting frequency
Instead for bass drivers is better to increase cabinet stiffness that shifts resonances above the cut frequency of the woofer
For this reason my ideal speaker is two pieces ... an head with mids and highs above a bass box This is what i have in mind A very old concept

 

[gino1961]

Before you build a box,

Hi and thanks for your very kind and precious advice
I am not that much in building The idea is taking some old speakers with a good potential and mod their cabinets
My final speakers will be two pieces ... a mid/high head above a bass box with some mechanical decoupling between the two
The more challenging is the bass box ... of course
A small two ways is very easy to get The choice is literally immense
But the bass box is demanding Fwiu the cabinet must be stiff Very stiff
The xover will be external to provide an easy access to parts

get some speaker design software and plug-in the T-S parameters. WinISD is FREE. It will help you optimize box size and port dimensions for a ported design.

i do not like much ported design I prefer to use a bigger woofer in a closed box ... something like a good 12"
I do not need to go very deep in my current home situation to get 50Hz would be enough

It will also help you to decide if a ported or sealed box is better (it depends on the driver parameters and box size) and you can experiment (virtually) with changes before you build anything. (WinISD is ONLY for the woofer/box. It won't help with integrating a crossover and tweeter, etc.)
...Normally, I'd advise playing around with the software before you buy the driver.

Thanks again I have already some tools ... from Dayton Audio to measure TS impedance and freq response They are excellent imho Very easy to use
For instance i have discovered that two vintage speakers have aged differently Their impedance curve is quite different
I wonder if the people who buy old speakers make any testing before buying them The tools work perfectly with a portable pc

And somebody can probably recommend a website about DIY speakers. There are also some good books but I can't recommend one because ones I have are either too old, or I have a "cookbook" where you can build one of the designs in the book. (I never built anything from the cookbook.)

I prefer the SW approach in the sense of downloading a sw and learning by using it Everyone uses a SW these days i guess
I will study the manual

That should be helpful but usually a calibrated mic is used to make "final EQ tweaks" or to help fix acoustic problems of the speaker and room combined.
You'll probably hear problems before you measure them, but measuring can help with diagnosis and it may help to tweak the crossover to "balance" the woofer and tweeter (and midrange if any) .

I have one cal mic from Dayton Audio The usb version

I assume you have downloaded REW?

I downloaded REW but it did not work with my audient sound card ... a problem with the gain (got a message)
I will try with another sound card for sure I see that is very popular There must be some reasons

Amir has a YouTube video about speaker measurements. (It runs about an hour.)
Unfortunately, few manufacturers publish detailed measurements and some don't have (and don't rent) the test equipment and/or anechoic chamber.

I will watch it with the greatest attention hoping to get the most I am very uneducated I studied chemistry and i am poor also at that

-----------------------------------------------------------
Back to the lead lining, etc...
Usually I just knock on the cabinet and if it rings/resonates it needs dampening or bracing. And when I build a speaker I usually put fiberglass inside as "standard practice". A small cabinet may not require bracing.

Thanks again I do something similar I have bought some 50mm diameter wooden balls to save my knuckles They are very handy
i am surprised how a same speaker has sides sounding quite different

They make adhesive vinyl which is sort-of the same idea as lead, but they say it's "light weight" so I'm not so sure how much it would help with wood. But you wouldn't have to worry about vibrating or rattling.
Stuffing or lining the box with fiberglass (or "less-nasty" speaker stuffing material) usually helps. That will also help with the internal resonances related to dimensions and
wavelengths. (Those wavelengths are not in the bass range.)

Very well I understand that above a certain level the vibrations have little energy so they can be tamed more easily than lower frequencies
But i see mid and high range less of a problem Bass is the problem The woofer is a beast with some tracks like pipe organ ones

 

[gino1961]

I would advise OP use vituix cad for this. It's enclosure tool is much better than winisd and a lot easier to use.

Hi thank you very much indeed I think that it will be a 3 ways in the end I was thinking about using a single wideband for mids and highs But their response is usually not very linear unfortunately
Some drivers have a strong peak at around 10k ... still in the audible range even for an old man like me ... i hear up to around 13k
5 years from now and this peak could not be an issue anymore

 

[dfuller]

I would advise OP use vituix cad for this. It's enclosure tool is much better than winisd and a lot easier to use.

Gonna have to teach myself VCAD.