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Phil Starr

1x12" Cab Design Diary

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I agree with Phil. Avoid the W version with foam surround unless you're going to use it in your car.

The other one looks like it might be rather good.

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So, I gave the modelling a try. Here are the Beyma in yellow, the Beta in red and the The Box (A) in gray. I took the measurements from the plans hosted in picasa a few pages back it gave me about 80 liters and it's tuned to 50 Hz.

I don't get a full range plot as you guys do, I don't know if it's the software or me. I'd be glad to be pointed what I'm doing wrong!

Cheers

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That's as predicted 80l is a big box for a single 12, put it into a 50l box and you should see the hump appear. I'm assuming you put Le into WinISD which is why you get the roll off at higher frequencies. The software doesn't 'know' the frequency response of the speakers so it is just calculating a theoretical frequency response for the whole system. It's only really very accurate at the bottom end.

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Well, evidently there's a difference between monkeys like me clicking buttons and people who knows their stuff!

The bump you predicted is quite visible (colors are the same as in the previous graphic I posted). Still it seems the speaker could perform quite OK.

I was thinking in getting the Beyma from Poland, as it would be a bit cheaper but, I could maybe attempt this build. Even if it fails horribly it would be a cheap lesson.

And goes without saying, thanks all of you for sharing so much knowledge!

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Just a quick addition to say I'm still happy with the version I built from the information/specs in this thread, and using the new version of the Beyma driver. In fact I'm twice as happy now as I was last time I posted, as I've finally finished the second cab, and used it at a practice the other day.

I was taken aback by the difference the second cab makes. I wasn't really sure what to expect, and was anticipating perhaps a bit more volume. What I actually got was oodles more bass than I expected - I usually run my Ampeg PF500 with all the EQ at 12:00, but by the end of the evening I'd backed the bass off to about 09:00. I can safely say that there is absolutely nothing lacking in bottom end for a four string player, and I think I understand some of the comments from others who've played your prototypes, Phil, that the flat response might sound odd to people who are used to a bit of a mid hump from many commercial cabinets.

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[quote name='hrnn1234' timestamp='1480069131' post='3181403']
Well, evidently there's a difference between monkeys like me clicking buttons and people who knows their stuff!

The bump you predicted is quite visible (colors are the same as in the previous graphic I posted). Still it seems the speaker could perform quite OK.

I was thinking in getting the Beyma from Poland, as it would be a bit cheaper but, I could maybe attempt this build. Even if it fails horribly it would be a cheap lesson.

And goes without saying, thanks all of you for sharing so much knowledge!
[/quote]

Ha ha, when I started it was all algebra and slide rules, every calculation took so long you tried not to make mistakes and were very conservative in what you did. Chienmortbb just recently described speaker design as being like squeezing a balloon, every time you tweak the design somewhere something pops out elsewhere.

I think given the time involved and the expense of the cab I'd pay the extra for the Beyma, you can see what it gives you on your graphs, it is also better finished than the Thomann so you'd hope it my be a little longer lasting.

[quote name='Gottastopbuyinggear' timestamp='1480080755' post='3181510']
Just a quick addition to say I'm still happy with the version I built from the information/specs in this thread, and using the new version of the Beyma driver. In fact I'm twice as happy now as I was last time I posted, as I've finally finished the second cab, and used it at a practice the other day.

I was taken aback by the difference the second cab makes. I wasn't really sure what to expect, and was anticipating perhaps a bit more volume. What I actually got was oodles more bass than I expected - I usually run my Ampeg PF500 with all the EQ at 12:00, but by the end of the evening I'd backed the bass off to about 09:00. I can safely say that there is absolutely nothing lacking in bottom end for a four string player, and I think I understand some of the comments from others who've played your prototypes, Phil, that the flat response might sound odd to people who are used to a bit of a mid hump from many commercial cabinets.
[/quote]

Yes I had the same experience, Two of them create a lovely creamy bass but I ended up rolling it back the same way so as not to excite room resonances and swamp the rest of the band. I glad you were happy enough to build a second cab.

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I looked into it a bit more and the air velocity gets way too high with the thomann speaker. Over 25m/s at about 30Hz.

That and the fact that there doesn't seem to be 63mm tubing available here it's making everything more tricky than what I expected!

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The air velocity isn't the problem so much as the excursion which is causing it! Air velocity will lead to some noises from your ports but the excursion will destroy your speaker. The reality is that your speaker won't go down to 30Hz at high power and neither will most commercial speakers. If you check out most of the designs on the Eminence website you'll see they usually recommend using a high pass filter to stop subsonics getting to pretty much any compact design using a ported cab.

In normal use there isn't usually too much signal coming out of the pups at these frequencies even with a 5'er but when cabs fail it is often down to someone pushing these frequencies through in an attempt to get 'more bass'

63mm tubing is ordinary gutter downpipe http://www.screwfix.com/p/floplast-downpipe-68mm-x-2-5m-black/25256 Their 68 is the outside diameter.

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Man, I feel really bad derailing the thread so much, but it's almist inevitable...

I imagined that the 30Hz wouldn't be much of an issue apart from the noise. I saw the graph posted by tks and understood that it's not "the most of the note" that resides so low in the frequency range but only the fundamental. I play with a 4 stringer but use an octaver so I woukd eventually have the problem of port noise. And although I don't know now exactly how it is in reality, you mentioned it as factor when choosing either 40Hz tuning or 50Hz, and that was with much lower velocities than this one.

The simulation shows as well velocities over 15m/s up to about 50Hz and although that's at the highest power, coukd eventually be an issue.

Still, rest assured that I changed my mind about going with the thomann speaker! The downsides keep surfacing and it will be probably for the best to base the build on your hard (and much more thorough) work instead of my nonsense.

I also missed to mention I'm in Austria. From what I gathered on the hardware stores here, there's a different standard for pipes, either 53 or 75 mm. I'll keep looking though!

You guys are the best- thanks again!

Edit: a general rule of thumb question, I couldn't find an answer to yet: how far can the ports go? How many cms to the back wall shouldnthere be?

Edited by hrnn1234

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Yes, we should probably have started another thread though I am sure interested other people are looking in.

I'd always recommend measuring the inside diameter of a pipe anyway. Then winISD will recalculate the length for you. You could look at three 75mm pipes as well they'd have a similar area to four of our smaller pipes. the other source of ports is the cardboard tubes that come inside rolls of carpet, carpet warehouses will let you have them for free as they are just waste for them. You could also try re-tuning the cab to 40Hz to see how that affects the excursion. Don't forget to check the maximum power chart too as you will lose out there at frequencies a little above the tuning frequency.

I don't like octavers on the bottom notes, in most of the rooms I play they either can't be heard or excite room resonances and make the band sound bad. One way round this is to use a HPF filter like a Thumpinator that will take out the lowest frequencies but leave the octaver to thicken up the notes when you are playing higher up the neck.

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If anybody wants it and is prepared to pay postage or pick it up I'm happy to give away my prototype cab. It isn't my finest work, as a prototype it's been modified a few times, and it's an empty box, the speaker has been returned to my PA cab and I've scavenged some of the fittings but if someone wants a Mk1 1x12 then its a working cab free to a good home.

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On 13/09/2018 at 11:56, Phil Starr said:

If anybody wants it and is prepared to pay postage or pick it up I'm happy to give away my prototype cab. It isn't my finest work, as a prototype it's been modified a few times, and it's an empty box, the speaker has been returned to my PA cab and I've scavenged some of the fittings but if someone wants a Mk1 1x12 then its a working cab free to a good home.

did someone take you up on this offer? If not then I’m very interested...

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On ‎31‎/‎12‎/‎2018 at 16:22, smarti said:

did someone take you up on this offer? If not then I’m very interested...

PM'd

 

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Just discovered this Diary, read through to page 25 and cannot find plans to make this cab.

Can anyone tell me if step by step details are available?

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Posted (edited)
2 hours ago, gocon said:

Just discovered this Diary, read through to page 25 and cannot find plans to make this cab.

Can anyone tell me if step by step details are available?

Plans are attached. Here's a video of Phil building the mk2 cab at a recent bass bash on a related thread: 

 

Basschat 1x12a.jpg

Edited by Johnny Wishbone

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Incidentally I would add that I'm a dreadful carpenter and managed to build two of the MK1 cabs fairly easily after watching this. They really are excellent. I'm selling my Orange 4x10 as a result.

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You poor thing. I hope it wasn't too dull. Though I admit I just looked through to find any useful information for you and did get distracted by some interesting contributions from people.

The big problem is that a lot of the links have gone down which happened when the Basschat site was moved. I've not got all of them saved either so difficult to put them all back up again. I never did do the step by step guide but I did build a slightly smaller version and put up a video of the build (link to follow) As ever bass playing and band changes get in the way, I love Basschat but prefer bass playing :)

The external dimensions are 360x424x530mm the baffle front is set back 30mm from the front of the cab so internally the depth is 306mm. The four ports are made of standard guttering downpipe 190mm for a 50Hz tuning. All this information is elsewhere in the thread but it's probably hard to find. The techniques are the same as the ones in the video.

I'll try and see if I can find any old pics and plans to put up but if you want to build one of these then I'm happy to guide you through the process. If you had been here a week ago I could have sent you one of the prototypes. Sadly someone else has bagged that one.

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Posted (edited)

Thanks Johnny. All done :)

 

I need to be able to type faster

Edited by Phil Starr
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That's a great video, which shows just how easy it can be to assemble a cab and provides some interesting insights along the way.

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Phil-many thanks. Video is most helpful and your summary of measurements, together with plans will get me there.

Great job, looking forward to the sound.

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On 13/09/2018 at 11:56, Phil Starr said:

If anybody wants it and is prepared to pay postage or pick it up I'm happy to give away my prototype cab. It isn't my finest work, as a prototype it's been modified a few times, and it's an empty box, the speaker has been returned to my PA cab and I've scavenged some of the fittings but if someone wants a Mk1 1x12 then its a working cab free to a good home.

Managed to find some time to put the Beyma 212 into the cab and have a quick play today. First impressions are very favorable as it sounds fantastic to my ears in the confines of my house. The acid test is to use it with the band. If we have a rehearsal soon I’ll try it out then. Unfortunately though the rest of the band don’t like reheasals much, preferring to just turn up and play!

Having turned the volume up as far as I dare, my feeling is that it won’t go loud enough for a gig with my amp as it’s 200w into 8ohm so I’m planning on building another cab... or getting someone else to do it as I have pretty much zero skills and equipment.

I haven’t yet done a side by side comparison with my Ampeg 4x10 but from memory this cab sounds a bit ballsier. Can’t describe it any better than that. I was also surprised at the amount of top end it has, not having a tweeter like my 4x10. So for my use it won’t need one which is a relief as I won’t need to get drilling!

I’ve ordered a grill as well, so all will be sorted when that arrives.

Many thanks for the generous gift Phil, I really appreciate it and Will enjoy using it in the months/years to come. Just need to get a second one sorted out now! I’ll post another photo when the grill is fitted.

20190120_170631.jpg

Edited by smarti
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