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give me a suggestion for an 8" sub

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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 12:22pm
with 21" could be better TongueTongueTongueTongueTongue

sorry but the goal of this project is using a 8", thats is the compromise that id like to stay under...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 12:58pm
Originally posted by _Natty_ _Natty_ wrote:

Originally posted by _Natty_ _Natty_ wrote:

Originally posted by BJtheDJ BJtheDJ wrote:

Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configuratu¡ions for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.

Isobarik cabs as well

i dont know a lot about isobarik enclosure... maybe a magnet to cone configuration coul be interesting.


I've read something about isobaric, and all articles that ive found describe the parallel way, but as I mention i need to wire them in series due the 8ohm loading for the module. 
So i simulate it with winisd, but it seems that just parallel is simulated. or I wrong?
I switched to bassbox pro 6, and trying different things the result of the sims isobaric/compound its extactly the same for parallel or series, but this is strange to me because the ts are trathed in different way or i wrong again?

the result is good, in comparison with my big double reflex:
-yellow double reflex (the one measured above)
-in red and green(not visible because is identical) the 2 curves of compound 20L parallel and series wired. the reflex is so long so i need to work around this






Have you checked if you will save on m³?





Earplugs Are For Wimps!
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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 1:14pm
Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

Originally posted by _Natty_ _Natty_ wrote:

Originally posted by BJtheDJ BJtheDJ wrote:

Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configuratu¡ions for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.

Isobarik cabs as well

i dont know a lot about isobarik enclosure... maybe a magnet to cone configuration coul be interesting.


I've read something about isobaric, and all articles that ive found describe the parallel way, but as I mention i need to wire them in series due the 8ohm loading for the module. 
So i simulate it with winisd, but it seems that just parallel is simulated. or I wrong?
I switched to bassbox pro 6, and trying different things the result of the sims isobaric/compound its extactly the same for parallel or series, but this is strange to me because the ts are trathed in different way or i wrong again?

the result is good, in comparison with my big double reflex:
-yellow double reflex (the one measured above)
-in red and green(not visible because is identical) the 2 curves of compound 20L parallel and series wired. the reflex is so long so i need to work around this






Have you checked if you will save on m³?






what u mean?
about ports? no are so long...needs to mods a lot


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 4:04pm
Aaah no - I meant will the isobaric design give you a smaller box. It should...   Smile




Edited by Earplug - 16 December 2020 at 4:05pm
Earplugs Are For Wimps!
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 4:07pm
Originally posted by _Natty_ _Natty_ wrote:


I've read something about isobaric, and all articles that ive found describe the parallel way, but as I mention i need to wire them in series due the 8ohm loading for the module. 
So i simulate it with winisd, but it seems that just parallel is simulated. or I wrong?
I switched to bassbox pro 6, and trying different things the result of the sims isobaric/compound its extactly the same for parallel or series, but this is strange to me because the ts are trathed in different way or i wrong again?

the result is good, in comparison with my big double reflex:
-yellow double reflex (the one measured above)
-in red and green(not visible because is identical) the 2 curves of compound 20L parallel and series wired. the reflex is so long so i need to work around this






You need to explore the Maximum Acoustic Power amongst both designs at the same wattage to determine if the isobaric will indeed offer the same performance compared to your reflex design.

Some TS Parameters will change once you configure the drivers from Parallel to Series. The Ohms Law plays a tremendous factor as you are altering the DC resistance load.

You should expect a -3 dB loss wiring two 8 ohm nominal drivers to equate a 16 ohm nominal load compared to a single 8 ohm nominal load driver operating own its own. All drivers and amplification power considered equal of course!

Best Regards,





Edited by Elliot Thompson - 16 December 2020 at 4:10pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 4:53pm
TangBand, Dayton, Omnes audio, Peerless/Typhany, SBacoustic all have some nice 8"s, some more suitable for CB, some for BRs of different size and tuning.
If i was you i`d consider their 10"s too as you might be surprised that some might have a better price/output/volume ratio :)

(I`d also take a look at the small cone TH DIY projects that float around the www.. if you are into real sub performance that requires fullrange tops)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 6:15pm
Originally posted by _Natty_ _Natty_ wrote:

Originally posted by bob4 bob4 wrote:

Hi Natty,
Which speakers are you using in your prototypes? 

For my taste, i definitely want 30 hz...... 

Have you tried to sinulate the cheaper driver in a bigger enclosure? Is it possible to get a lower low corner?  If it is so cheap, maybe you could use multiples.....

I remember there is also a trick of connecting a capacitor in series or parallel with the woofer to manipulate overall q value and get lower bass..... forgot the proper terminology for this. 

Since it is for hifi and indoors, you could consider open baffle as well.
I use two 12" woofers on a single 250w channel with eq boost in a small room (10 sqm, concrete apartment building). Gives good punch AND full deep notes down to 30 hz. 

Even some old studio1 ska 7" have 35hz double bass notes, i can feel them Smile



I dint mention the speakers brands just to talk in neutral way about ts, enclosure and performance.

the cheap, si not really cheap but cheaper than most hifi cones it comes from PA and def is not a speaker designed for sub, but it have a lot of sensibility and untill reach its fs its works and break it, its almost impossible.

The wrong step about multiply speakers its allready done with the other configuration thats have the significant risk to be too big in the final projects when shapes will matter!
it can takes until 600w as peak so if i run multiple, i take some serius risk of underpowering and square waves can be really dangerous....
and coupling I dont think thats can gives under hz... fs is 51hz, and as you can see i move it of around 40hz by set the Fb of the box around 40hz.
Vas is tiny -15l- so if i make bigger i think to loosing controls over transient could be the only result or I wrong?

I think that u mention some teqniques for lowering Qes, but not clear to me how to mod it for having different response, but if you have some link to read it could be interesting as esperiment!

One of the best home system that ive ever heard was about 4 15" in a open baffle powered by 3w of valves each!!!!so i can understand what u saying but its not the goal of this project, it will comes with a proper shape ;)


https://forum.speakerplans.com/solid-35hz-in-4-cu-ft_topic81523_page3.html

if you just want a cap in series with a sealed box then it is third order - quicker to play around with the filter tool in hornresp rather than read theory.


Edited by snowflake - 16 December 2020 at 6:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2020 at 4:48pm
the driver of the double are 4ohm, so for this i use them in series, for the 8ohm needed by the module.

Sims above are magnet to cone, series, the sims not seems bad, but if those -3dbs are missing, or the sims program lies or this config is lossless in comparison with the reflex, that seems impossible from what ive read...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Meat Substitute Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2020 at 5:05pm
Volt make some of the nicest 8" drivers. Plenty of different choices of types but every one I've played has sounded very nice.

If you have the budget and must have the extra output 2 smaller drivers can be better than stepping up in size sometimes.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2020 at 5:15pm
Originally posted by _Natty_ _Natty_ wrote:

the driver of the double are 4ohm, so for this i use them in series, for the 8ohm needed by the module.

Sims above are magnet to cone, series, the sims not seems bad, but if those -3dbs are missing, or the sims program lies or this config is lossless in comparison with the reflex, that seems impossible from what ive read...



The sims are correct however, you are just looking at the wrong chart. "Normalized Amplitude Gain" is cabinet gain. It has no influence on how much power you are feeding the loudspeakers(s). It tells you how efficient the loudspeaker will be at the given frequencies based on the enclosure size.

Also you need to half the power on the wattage you are feeding each driver if you driving them into series.

In other words, you are feeding 75 watt to each driver which totals 150 watts for both drivers as you are configuring the drivers into series. Realistically speaking, you are supposed to enter the amplifier power at the given load in the Pe if you want a more truthful answer. It does not matter what the wattage of the loudspeaker states. What matters is how much power can you feed the loudspeaker at the given load.

The Pe determines the power listed on all the charts except "Cone Displacement," "Vent air Velocity" and, "Custom Amplitude Response."

Harristech Software is a more in depth program so you need to have a good understanding on what you are doing. You should be focusing on Maximum Acoustic Power since you are comparing one design to another.

Best Regards,


Edited by Elliot Thompson - 18 December 2020 at 5:24pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2020 at 5:44pm
Originally posted by Meat Substitute Meat Substitute wrote:

Volt make some of the nicest 8" drivers. Plenty of different choices of types but every one I've played has sounded very nice.

If you have the budget and must have the extra output 2 smaller drivers can be better than stepping up in size sometimes.

volts make some very nice drivers but what ive pointed are 250 euros each...so too much!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 18 December 2020 at 5:48pm
Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by _Natty_ _Natty_ wrote:

the driver of the double are 4ohm, so for this i use them in series, for the 8ohm needed by the module.

Sims above are magnet to cone, series, the sims not seems bad, but if those -3dbs are missing, or the sims program lies or this config is lossless in comparison with the reflex, that seems impossible from what ive read...



The sims are correct however, you are just looking at the wrong chart. "Normalized Amplitude Gain" is cabinet gain. It has no influence on how much power you are feeding the loudspeakers(s). It tells you how efficient the loudspeaker will be at the given frequencies based on the enclosure size.

Also you need to half the power on the wattage you are feeding each driver if you driving them into series.

In other words, you are feeding 75 watt to each driver which totals 150 watts for both drivers as you are configuring the drivers into series. Realistically speaking, you are supposed to enter the amplifier power at the given load in the Pe if you want a more truthful answer. It does not matter what the wattage of the loudspeaker states. What matters is how much power can you feed the loudspeaker at the given load.

The Pe determines the power listed on all the charts except "Cone Displacement," "Vent air Velocity" and, "Custom Amplitude Response."

Harristech Software is a more in depth program so you need to have a good understanding on what you are doing. You should be focusing on Maximum Acoustic Power since you are comparing one design to another.

Best Regards,

thanks a lot maybe i dint understand this before, 150w is the rms of the spakers. What ive from the amp module is 300w@8ohm.
ill check what are uou saying later.
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