New BassChat 8"Cab design

[Phil Starr]

23 hours ago, Rosie C said:

 

I share your puzzlement. My 'new' Trace Elliot cabs have substantial metal grilles on them and a 4"x3" brand badge obscuring one of the 10" drivers. To the uneducated it seems like they would obstruct the sound.

 

Any sort of obstruction in front of the speaker affects the sound and if you listen to music then there is an audible difference when you remove the grille. Most Hi-fi buffs will remove them for critical listening and you never see them on studio monitors. However practicality reigns and bare paper cones would last minutes in most gigs never mind rattling around in the back of the van. Quite apart from the resistance to air movement the holes each act as diffraction points and a metal grilla as a diffraction grating. The hole size is important as is the ratio of open space. The effect is most evident at high frequencies and is clearly audible. 

 

I look for holes that are as big as possible whilst keeping anything as big as a pencil out. I'd avoid anything with more than 40% of the area covered so not all perforated metal sheet is suitable. Fortunately there isn't much high frequency coming from a bass speaker and so the sound isn't too badly distorted by the grille. Most commercial grilles will be OK so have a look at what the manufacturers do and you should be OK. However I do look at some cabs and wonder if style over substance isn't creeping in. You really don't need to put the badge in front of the cone.

[Phil Starr]

Grille for the BassChat 8 

 

Somebody, I can't remember who, used one of the round grilles for an 18" speaker and hammered it flat, I copied that idea for my cab it's a great way of buying just enough perforated metal to do the job and is purpose designed. it even comes in black   £6

 

https://www.ebay.co.uk/itm/126150460308

 

[rwillett]

@Phil Starr

 

Thanks for this. I'll work out how to mount the grill a few mm back from edges of the speaker cabinet. I should be able to get 15mm from the very front of the speaker to the grill. That's around 21mm from the cone. 

 

I'll look around for 10mm perforated aluminum and some acid etching primer. 

[rwillett]

I wonder if chicken wire would work? 

 

Pros: Cheap, little metal to space ratio, easy to work with. 

 

Cons: cheap, might look like crap, would bend easily. Probably better for keeping chickens in than protection. 

 

The round speaker grille is great but the delivery is the same price as the grille. 100% delivery costs feels wrong to me for some reason.

 

 

[LawrenceH]

35 minutes ago, rwillett said:

I wonder if chicken wire would work? 

It did for these guys

Edited yesterday at 10:13 by LawrenceH

[rwillett]

Just looked at whether I could print a decent protective mesh. I could have done some clever measurements but I just plonked the speaker on the print plate.

 

Its a fraction too big for a single print. A 300mm x 300mm printer would handle it, and would be easy to design for but I don't have one. Not sure if I want to glue two pieces together either  

 

Back to eBay and silly delivery prices, though as I need two grills I suppose that halves the delivery costs. Yes it's irrational 😁

 

Rob

Edited yesterday at 11:42 by rwillett

[Phil Starr]

1 hour ago, rwillett said:

I wonder if chicken wire would work? 

I have contemplated using welded wire mesh, as sold to gardeners. my thought was to use it to protect the speaker but to cover it with fabric. There's a wider range of fabrics available for hi-fi cabs but it's too flimsy to protect your speakers at a gig, a sub layer of mesh could protect the speaker but give you the look of fabric.

[nekomatic]

1 hour ago, rwillett said:

The round speaker grille is great but the delivery is the same price as the grille. 100% delivery costs feels wrong to me for some reason.

CPC sell them so if you can think of sixteen quid’s worth of other stuff you need from CPC (and who amongst us can’t do that?) then you can get free delivery. 
 

To be honest even if you have to pay delivery I’d struggle to find a cheaper way of making a decent grille, as long as you have the means to cut it (I used a Dremel but am sure hacksaw or tinsnips would do). Note that the plastic edging is just a stretch fit around the round grille so you can re-use it (with glue) for the rectangular version. 

[Phil Starr]

https://www.ebay.co.uk/itm/156983722403 

 

A pair with free delivery, eBay is weird and wonderful. I hadn't looked at the delivery but it's fairly normal to see the same item from the same supplier with two different prices and delivery costs but strangely adding up to the same cost. Anyway I just wanted to show you what to search for. Thanks to @nekomatic for the idea which I have unashamedly copied. Beat it flat with a rubber mallet by the way, as the paint comes off fairly easily. It cuts with tin snips and with a disc cutter.

[LawrenceH]

Depends how rough you are on your gear but I think the Fender-type grill cloth served well enough for a lot of users. Lightweight, easy to apply, looks classic

[rwillett]

There's some great ideas here. Lots of clever things to try which I would not have thought of. 

[tauzero]

21 hours ago, rwillett said:

 

The ^2 notation is nothing to do with imperial or metric but is a computer way of describing something to the power 2. So x^2 means x squared or x x x (which is really confusing) as we sometimes use x to mean times. We could also say x * x.

 

Many computer languages use the ^ symbol as the notation for "to the power of" as you can't use a superscript as languages are based on the ASCII character set. 

 

Also can be notated as x**2 (which has strangely moved the asterisks so they aren't level with each other).

[rwillett]

11 minutes ago, tauzero said:

 

Also can be notated as x**2 (which has strangely moved the asterisks so they aren't level with each other).

I'd forgotten that one. Which language was that from?

[tauzero]

17 minutes ago, rwillett said:

I'd forgotten that one. Which language was that from?

 

It's certainly in COBOL - COMPUTE statement. IIRC it's also in FORTRAN although it's 55 years since I used that. BASIC used ^.

[tauzero]

Here's the grille I've got - perforated aluminium sheet, 10mm holes, with the speaker on top to give a good idea of scale.

 

[rwillett]

That does look good...

 

Very tempting....

 

Spent an hour before torrential rain hit (again)

1. Glue front and back panel
2. Route the edges so there's a nice curve Nice 6mm routing bit makes this dead easy (as previously suggested)
3. Solder speaker wire to the speaker
4. Fill and sand any problems.
5. Paint front baffle matt black.
6. Take off side handles and rear speakon panel, and paint the wood matt black. I'll mask this area off before the Armacab goes on.
7. Assemble, check all OK
8. Check it all works.
9. Wait for warm weather to do the Armacab. - July 2027? 

[rwillett]

Has anyone painted their cab with the Armacab from Penn-Elcom?

 

Interested in the drying time, mins, hours, days or weeks? As it's 7-8c here, it could be a long time. 

[Chienmortbb]

2 minutes ago, rwillett said:

Has anyone painted their cab with the Armacab from Penn-Elcom?

 

Interested in the drying time, mins, hours, days or weeks? As it's 7-8c here, it could be a long time. 

No idea, but the viscosity will be higher at 7-8C rather than the 23C quoted on the data sheets. Contact for tech support is http://elastothane.com/aboutus.html#technical

[Chienmortbb]

This is the prototype with the 10 mm grille that @tauzero shows above. I painted it grey but in pictures it is so light, it looks untreated.

Aluminium is light, but it needs special paint. I have used a few and none are perfect. Research suggests Hammerite https://www.hammerite.co.uk/en/products/hammerite-special-metal-primer?size=250ML.

 

Finish with https://www.hammerite.co.uk/en/applications/hammerite-ultima.

 

It will not be cheap though and maybe a mild steel grille or leaving the aluminium to tarnish naturally could be the answer.

Edited 4 hours ago by Chienmortbb

[Stub Mandrel]

23 minutes ago, Chienmortbb said:

This is the prototype with the 10 mm grille that @tauzero shows above. I painted it grey but in pictures it is so light, it looks untreated.

Aluminium is light, but it needs special paint. I have used a few and none are perfect. Research suggests Hammerite https://www.hammerite.co.uk/en/products/hammerite-special-metal-primer?size=250ML.

 

Finish with https://www.hammerite.co.uk/en/applications/hammerite-ultima.

 

It will not be cheap though and maybe a mild steel grille or leaving the aluminium to tarnish naturally could be the answer.

 

Imagine anodising it 😍

[rwillett]

That would look great.

 

I did look at anodising some telescope parts years ago, the theory looks quite easy, its the practise that worries me...

[stevie]

3 hours ago, rwillett said:

Has anyone painted their cab with the Armacab from Penn-Elcom?

 

Interested in the drying time, mins, hours, days or weeks? As it's 7-8c here, it could be a long time. 

 

I started using it recently. The drying time depends on the ambient temperature and air moisture level. It will dry OK at temperatures of around 10 degrees. I leave each coat for a day at the moment but drying outside with a bit of wind is faster. You should be all right at current Yorkshire temperatures, although it would probably be best to paint in the morning and avoid overnight drying when the temperature is expected to drop to 0 degrees.

[rwillett]

42 minutes ago, stevie said:

 

I started using it recently. The drying time depends on the ambient temperature and air moisture level. It will dry OK at temperatures of around 10 degrees. I leave each coat for a day at the moment but drying outside with a bit of wind is faster. You should be all right at current Yorkshire temperatures, although it would probably be best to paint in the morning and avoid overnight drying when the temperature is expected to drop to 0 degrees.

Stephen

 

Thanks for this. Ambient temperature is around 7-8C, air moisture level is pretty much saturated as it's raining constantly such that flood warnings are in place and I am told Keswick Campsite is being evacuated which is a step into the unknown.  Very little wind so air drying is probably not on. I do have a nice space heater courtesy of ScrewFix so may use that and see how it works. I suspect without artificial heat, we're into next year for painting  

 

Rob

 

[nekomatic]

3 hours ago, rwillett said:

I did look at anodising some telescope parts years ago, the theory looks quite easy, its the practise that worries me...

 

If you're banned from even painting indoors I don't think anodising is going to be on the cards!

[basstone]

1 hour ago, rwillett said:

Stephen

 

Thanks for this. Ambient temperature is around 7-8C, air moisture level is pretty much saturated as it's raining constantly such that flood warnings are in place and I am told Keswick Campsite is being evacuated which is a step into the unknown.  Very little wind so air drying is probably not on. I do have a nice space heater courtesy of ScrewFix so may use that and see how it works. I suspect without artificial heat, we're into next year for painting  

 

Rob

 

Space heater should do the trick. I used Tuffcab on some big band music stands this timelast year and used a hot air gun and fan heater to help the drying process. Just beware that the paint may remain soft under the outer skin for several days. Somerset also has similar conditions ATM. Hope it goes well