vinceom

3 hours ago, Phil Starr said:

It's like looking at an old friend

Well done, it's great to see a successful build. I really hope you get as much fun out of it as I have as soon as the restrictions are lifted and you can get out with your band.

FWIW I never worry about 'breaking in' a cab. The first few hours are best spent playing bass IMO and with a new cab I'm going to spend at least an hour playing bass, trying all my amps and basses in turn and fiddling with eq, but then I need all the practice I can get. The changes in sound from breaking in aren't dramatic and a few people have questioned whether you can hear them at all. 

Thank you Phil. I was very lucky to arrive few weeks ago to your messages and on basschat. The result wouldn't be so great. Thanks again for all your advices. And your video on Youtube is very useful !!

Vinceom

Hi everyone 

here it is my bass cab . Sound is great. 

Question : does the driver need a break-in period and what is the best way to do it?

thanks!

Vinceom

Hi

This is the cab with ports (flared diy !). The cab itself passed the "knuckle" test, very very little vibration of cab panels. Tomorrow, i'll  bevel the edges with a 12mm radius router.

Vinceom

On 18/04/2020 at 10:23, Phil Starr said:

coming along nicely

It is such a simple construction technique isn't it?

Hi everyone

building the cab is very easy. But I had some problems with the ports. I can’t measure impedance to check whether tuning frequency is ok so I tried with rice on the cone. It didn’t work very well. So I trusted Winisd and cut the pipe to the right sound. And sound’s pretty good !

One more thing : is it a problem if the cab is not 100% air proof ? 
Thanks!

Vinceom

Hi

and here is my cab. Thank you very much for the advices. The events aren’t made for the moment (because of the covid, my 80 mm cylindar saw is in my other house).

Some informations : Okoumé plywood 15 mm,  bracket and bracing 20x20mm. The driver is a Beyma SM212.
external dimensions : H430xW500xD360
internal dimensions: H400xW470xD300

The amp head is TC electronics BH250.

I will try tomorrow morning the sealed version.

Thanks to all of you guys !

Vinceom
 

Thanks

If I already had the driver, i could check with a ruler ... I'm ordering this week all I need for my cab and i don't know this information.

Vinceom

Hi everyone

Is there someone who remembers what is the width of Female Disconnect Crimp Terminal to plug wire to Beyma SM 212? Impossible to get this information ...

Thanks !

Vinceom

Hi

did you check the tuning by mesuaring impedance or with rice on the cone ? And finally, what was the tuning ?The ports lentgh were calculated to have a tuning about 50 Hz.

thanks

Thank you mery much Phill.

Vinceom

Hi Phill

I have one more question. When i make a simulation with Winisd, with 2 ports of 64 mm diameter and Fb = 50 Hz and Vb = 30L, Winisd calculates 21 cm for the length of the ports. Winisd calculates 16 cm for the length if Vb = 37L, the external volume of the box .

So ? How did you calculate 16 cm for the length of the 2 ports ?

Thanks

Oh yes ! I didn’t remember.

Thanks

Thanks Phill. I calculate height 53 cm with a cross multiplication on the video, not very accurate... The cab seems big for only 30L ! I don’t know yet if i build a 30L or 50L. What did you lose with your 30L cab? Loudness ? But you get more accuracy in sound ?

I will load the Beyma SM212 and i want to hear its 350W !(my bass amp head is TC BH250 250W)

Thanks !

Phil, what are the dimensions of your box in the video page 1 ? The front panel is about 53 cm height. It's not the height of your 30L. Are there dimensions of your first cab (50L) but with only 2 ports ? And what are diameters and length of the 2 ports ?

Thanks, take care

Vinceom

Ok. Thanks Phil!

Thanks for answering quickly ! Can you send me your Winisd project for SM212 in your first cab (50 L), thank you. You are a reference in DIY bass cab !

Last question : What is the avantage to create 4 ports instead of 2 ?

VInceom

Thanks !

Hi. I’m thinkîng of building the 50 L cab. Is there someone who tried to load the Beyma 12CMV2? Specs are close to beyma SM212’s. (And 12CMV2 is 50€ cheaper).

Phil, do you recommand this one?

thanks !

Vinceom

On 29/09/2016 at 14:59, stevie said:

John, I think you'll find your cabinet is tuned too high. My calculations say you've tuned to around 60Hz. With that tuning, you'll be exceeding xmax at 40Hz with an input of 200 watts. As you have also applied bass boost, this figure could easily drop to 100 watts or less.

Tuning to our recommended 50 Hz will give you an extra 3dB at 40Hz, perhaps making bass boost unnecessary. The speaker will then also handle an input of 350 watts without exceeding xmax (at least in theory).

You might like to check the tuning frequency using the rice grain test. Use your good driver obviously. This works on the principle that driver movement is greatly reduced at the cabinet tuning frequency, because that's where the port is doing most of the work. Turn your speaker on its back and sprinkle a few grains of rice in the centre of the cone. Then go to this site (or something similar): <http://onlinetonegenerator.com/subwoofer.html>, play the frequencies and you will see the rice dancing up and down along with the movement of the cone. As you approach the tuning frequency, movement will slow down. The point at which the rice moves least is your tuning frequency, and this will be shown on your display.

Then get back to us.

PS Try this with your good cab with the round ports first. You should get a tuning frequency of 54Hz.

Hi

can you explain how you calculate tune frequency of your cab ? With Winisd ?

Thanks !