New BassChat 8"Cab design

[Phil Starr]

This is going to be a design for an 8" 200W cab for loud home use/practice or use a pair for a lightweight portable gigging rig. It's clean sounding with a rich bass for such a small cab and I will get the design up over the next few weeks. This is just a taster. For those of you who play upright we have tried the cab and this cab pairs really well with a 'proper' bass.

 

This was a covid/lockdown project and was meant to be a one off for @Chienmortbb to physically match his souped up Ashdown After Eight Combo. It was never meant for publication in this form. It's an unusual shape for a cab, almost a cube which is all 'wrong' acoustically but it looks really cute and sounds great so I'm publishing it like that. I may build another as a conventional shaped cab and put up both designs.  The cab is 33x33x30cm and will probably cost you less than £100 to build. It uses the simplest construction method possible. I've added a couple of pics so you can see just how bijou this little cab is. @RichardH has kindly offered to do some proper drawings.

 

 

 

 

 

Edited July 11, 2023 by Phil Starr

[Phil Starr]

This is based upon the Fane Sovereign 8-225, a nice little driver for bass, not least because it only costs £45. It has a good sized magnet for a little speaker so they manage to have good excursion and power handling plus high efficiency. the deepest bass is a bit limited but not by as much as you would expect and this gives a really satisfying sound in a small to medium sized room. The frequency response is 55-5,000Hz which pretty much covers the whole output from your bass without needing a horn.

 

Red line is on axis and blue is 45degrees off axis

 

Power handling 225W AES

Excursion 5.5mm

Efficiency 97db/W

Response 55-5,000Hz

Edited July 10, 2023 by Phil Starr

[Phil Starr]

Please note that this is a placeholder of the original cab design, we are working on an updated design which will make it much simpler (and cheaper) to cut out of a quarter sheet of 12mm ply. It's exactly the same volume but the weight has been reduced and it's a marginally different shape.

 

 

 

 

Edited July 16, 2023 by Phil Starr

[Phil Starr]

Quick update, the drawings have gone off to be done properly. One day I need to get to grips with something better than pencil and paper, but that would mean less time with sawdust

 

Fane have been fiddling with their speaker designs again but this time an improvement to the Sovereign 8-225. WinISD calculates sensitivity at 94db but there are some peaks in the mids which is how they measure 97db. The speaker should be capable of 116db continuous across the pass band, so very good for a little speaker. No doubt most manufacturers would claim 122db peak but that is ridiculous and I don't need to sell anything. However two of these would give you 122db which easily passes my threshold for a gigging speaker.

 

A 2x8 version would be interesting.

Edited July 11, 2023 by Phil Starr

[GlamBass74]

2 x Sovereigns purchased

 

This looks like fun!

 

 

 

[Phil Starr]

1 hour ago, GlamBass74 said:

2 x Sovereigns purchased

 

This looks like fun!

 

 

 

You are hooked  

 

If you'd rather do a 2x8 it's only a matter of recalculating the port and building a box double the size. Let me know if you fancy that.

[Matt P]

i can see this making a fantastic personal monitor for EUB , any chance of it having some kind of kickback option? I'm thinking it would be a great cab for small gigs and then a personal monitor for use when running into a PA. something along the lines of the crazy 8/88

 

just a 45 degree cutout on one edge would be enough.

 

Matt

[plankspanker]

Really interesting!  

I think I could manage a box like that - what do you think of incorporating one of these https://www.thomann.de/gb/the_tamp_pm40c_endstufenmodul.htm ?

Perhaps mounted externally on the rear panel but with the four sides extended by a couple of inches to provide protection. Only 50W (and that's at 4 ohms) but it could be a fun project and actually quite useful.

[Phil Starr]

3 hours ago, Matt P said:

i can see this making a fantastic personal monitor for EUB , any chance of it having some kind of kickback option? I'm thinking it would be a great cab for small gigs and then a personal monitor for use when running into a PA. something along the lines of the crazy 8/88

 

just a 45 degree cutout on one edge would be enough.

 

Matt

The thing about a self build is that you can modify it as you wish. You are only limited by your carpentry skills and your imagination. Keep the internal volume and port the same and it's very unlikely you will go wrong. If you decide to go ahead I'll help all I can.

[Phil Starr]

1 hour ago, plankspanker said:

Really interesting!  

I think I could manage a box like that - what do you think of incorporating one of these https://www.thomann.de/gb/the_tamp_pm40c_endstufenmodul.htm ?

Perhaps mounted externally on the rear panel but with the four sides extended by a couple of inches to provide protection. Only 50W (and that's at 4 ohms) but it could be a fun project and actually quite useful.

Go for it, Some people have also gone for using a car amp module running off a 12V battery. You'd get about 110db which would be plenty for very loud home practice or playing along with acoustic instruments 

[Phil Starr]

I've swapped the pictures on the first post for something that shows the size a bit better, looks like the amp was made for it

[GlamBass74]

Given the size, could you fit a top hat in the bottom panel and have it on a speaker stand? 

 

Near ear monitor 😁

[plankspanker]

 

 

My gigging rig is a Streamliner 600 and a pair of Berg HD112s. Your Bugera looks identical except for that handle on the edge so it gives me a good idea of the scale.

 

A few questions if you have the time;

1) The sheet material appears to be 18mm - is that ply, MDF or something else?

2) I've made quite a few storage boxes using my biscuit jointer and 18mm mdf - they are heavy but strong. As this would be a solid box without an opening lid do you think it would be okay to not bother with the 20x20 bracing struts?

3) The port is 68mm diameter - is it a piece of plastic downpipe?

4) Is the speaker screw-mounted to the inside or the outside of the baffle?

5) The speaker grille - is that cut from a bigger piece or did you size the cabinet to suit a piece that was bought that size?

 

Many thanks in advance!

[tauzero]

Could it be built with 12mm ply, and if so, would it need some bracing?

[Phil Starr]

It could be built with 12mm ply or 18mm MDF if you didn't mind the weight. I used 18mm ply because I was matching the Ashdown  combo for @Chienmortbb I'd have made it a slightly more orthodox shape and out of 12mm ply if it had been for me. Bracing is always good  but the simplest method is to pass lots of bass through the cab and feel for vibration and brace it where it is worst. 18mm and small panels meant this cab didn't need any more than the corner braces that are part of it's construction. I also had a stock of 18mm ply to hand and the original was built during lockdown. John provided the grille so I don't know where it came from. Yes it is plastic drainpipe. I always try to use something easy to obtain for these designs though I have stocks of cardboard tube for some of my own builds. The speaker is front mounted

 

The advantage of building yourself is that you can adapt these designs. Keep the internal volume the same and the port and you should be fine.

[Downunderwonder]

10 hours ago, Matt P said:

i can see this making a fantastic personal monitor for EUB , any chance of it having some kind of kickback option? I'm thinking it would be a great cab for small gigs and then a personal monitor for use when running into a PA. something along the lines of the crazy 8/88

 

just a 45 degree cutout on one edge would be enough.

 

Matt

Calculate volume missing in your wedge cutout and add it to the front by making the sides and top that much deeper, bottom too but it's smaller for the 45° piece missing, only mention so you don't cut it 'short' AND at 45°.

 

For my money it would be easier to make the box and then run the saw through it at the 45°.

 

Other option tilt the baffle. What gets added at the bottom gets taken away at the top, same volume. Mind the port doesn't get snarled on the bottom, or the driver if you port it from the back. You could even put the port in the side so it goes under the driver sideways.

[Matt P]

8 hours ago, Downunderwonder said:

Calculate volume missing in your wedge cutout and add it to the front by making the sides and top that much deeper, bottom too but it's smaller for the 45° piece missing, only mention so you don't cut it 'short' AND at 45°.

 

For my money it would be easier to make the box and then run the saw through it at the 45°.

 

Other option tilt the baffle. What gets added at the bottom gets taken away at the top, same volume. Mind the port doesn't get snarled on the bottom, or the driver if you port it from the back. You could even put the port in the side so it goes under the driver sideways.

I've already done some calculations, to get a 45 degree cutout with a 16cm ish base (which i think will be enough) adding about 3cm to the overall height(or indeed depth) would work, that was done before the drawings were available so the actual dimension would still need to be calculated. Easy enough to make some calculations to find the centre of gravity and make sure it's stable.

 

i think one of these might be my first DIY cab project, with the low cost i won't have much to lose if i end up with a pile of firewood and a driver.

 

the only slight issue is that except as a EUB wedge monitor I don't really have any need for this, and space is at a premium in our little house.

 

Matt

[Chienmortbb]

1 hour ago, Matt P said:

r I don't really have any need for this, and space is at a premium in our little house.

It really is tiny Matt.

14 hours ago, plankspanker said:

The speaker grille - is that cut from a bigger piece or did you size the cabinet to suit a piece that was bought that size?

The grille was a bit of a cheat. It comes from the original Ashdown combo. So the Ashdown is currently grille less. I have used a company on eBay before for my grilles. I will look them up and see what they can do.

 

I had a play with it and the Bugera amp last night. Apart from the volume, obviously I can’t use gigging,  I had to add a bit of bass but as I usually cut the bass slightly, it was still only at 12 o’clock.

[nekomatic]

Thanks so much for digging this out! I’d been contemplating building the 6 inch micro cab as a take-on-the-bus-able counterpart to my 1x12, but this looks to hit the sweet spot of oomph versus transportability. 
 

I can’t promise when I’ll get to building one but I think I have enough board lying around for it, so it’s only making the time to get started. That and buying a few clamps…

[Chienmortbb]

22 minutes ago, nekomatic said:

Thanks so much for digging this out! I’d been contemplating building the 6 inch micro cab as a take-on-the-bus-able counterpart to my 1x12, but this looks to hit the sweet spot of oomph versus transportability. 
 

I can’t promise when I’ll get to building one but I think I have enough board lying around for it, so it’s only making the time to get started. That and buying a few clamps…

Lidl have clamps in the Middle at the moment😄

[Phil Starr]

19 minutes ago, Matt P said:

and space is at a premium in our little house.

Would it help if you made this your main practice speaker and could store everything else out of sight? 

 

If even this is too big there is a smaller alternative https://www.basschat.co.uk/topic/455858-house-jam-micro-cab/ 

[Phil Starr]

55 minutes ago, nekomatic said:

Thanks so much for digging this out! I’d been contemplating building the 6 inch micro cab as a take-on-the-bus-able counterpart to my 1x12, but this looks to hit the sweet spot of oomph versus transportability. 
 

I can’t promise when I’ll get to building one but I think I have enough board lying around for it, so it’s only making the time to get started. That and buying a few clamps…

This may help you decide which is best for you. It's the bass response of both speakers as calculated by winISD @ 100W. Surprisingly both are equally loud but the 8" cab will handle another 100W at this point, adding an extra 3db, and whilst the 6 handles all of the second harmonic upwards equally well there is a lot of extra fundamental with the 8. In a small room at home the 6 sounds way better than you'd expect, light agile and crystal clear and not as bass light as you'd think. Perfect for not annoying neighbours and satisfying to play. The 8 has a more authoritative sound though and is comparable with a much bigger speaker..

 

[Jackroadkill]

On 11/07/2023 at 10:40, Phil Starr said:

If you'd rather do a 2x8 it's only a matter of recalculating the port and building a box double the size

 

Could this be done with a rectangular box with an internal baffle and two ports of the original size?

[Phil Starr]

1 minute ago, Jackroadkill said:

 

Could this be done with a rectangular box with an internal baffle and two ports of the original size?

No

 

[Phil Starr]

So just for interest this is a comparison of the frequency response of the 8" cab (in green) with a much bigger cab. It's the 15" driver used in the original Barefaced Super Compact in a 50l cab (Blue). The 8" speaker is bassier than the 15 if you are looking at the fundamental frequencies at the bottom end of a four string bass. 

 

 

Mind you the 15 is a whole 5db louder for the same power