New BassChat 8"Cab design

[Obrienp]

So it’s not necessary to use some specialist hifi speaker cable?

[Stub Mandrel]

12 hours ago, nekomatic said:

6 A twin core mains cable would also be fine. 

 

I just always seem to have some around when doing speaker things...

[Bassybert]

The only cable I use is ultra low capacitance, oxygen free, double wrapped with Kevlar, a gluten free hemp covering and the copper was mined on a Tuesday. It’s the only stuff I use. 

Edited December 6 by Bassybert

[Phil Starr]

On 05/12/2025 at 11:58, rwillett said:

Solder speaker wire to the speaker <-- What size wire is OK for 250W? I definitely have AWG16 and might have some thicker in a box somewhere in my basement. I've heard AWG 14 should be used

all the answers are good. The thing is that you really don't need to oversize. The resistance of the cable is going to be close to zero because you are dealing with a really short length. As to power handling you hve to remember the speaker is playing music not continuous current. Most of the time there is little or no signal and any note you play decays quite quickly. It's normal to think in terms of a duty cycle of 15-20% but that is allowing for a considerable safety margin, under 10% might be more 'real world' use so 20W for your 225W speaker would be a more reasonable rating. 

 

The voice coil of your speaker is wound with hair thin copper wire only slightly thicker than the strands in your cables and that doesn't burn out in normal use. Like @Stub Mandrel I use a couple of cores from any mains cable laying around most of the time, even 1mm lighting cable is plenty big enough. The reason speaker cables use thicker wire is to keep resistance to a minimum on longer cable runs. That's not relevant for the 40cm wire inside the cab.

[Rosie C]

1 hour ago, Phil Starr said:

The voice coil of your speaker is wound with hair thin copper wire only slightly thicker than the strands in your cables and that doesn't burn out in normal use. 

 

That puts it into perspective! 

[rwillett]

2 hours ago, Phil Starr said:

all the answers are good. The thing is that you really don't need to oversize. The resistance of the cable is going to be close to zero because you are dealing with a really short length. As to power handling you hve to remember the speaker is playing music not continuous current. Most of the time there is little or no signal and any note you play decays quite quickly. It's normal to think in terms of a duty cycle of 15-20% but that is allowing for a considerable safety margin, under 10% might be more 'real world' use so 20W for your 225W speaker would be a more reasonable rating. 

 

The voice coil of your speaker is wound with hair thin copper wire only slightly thicker than the strands in your cables and that doesn't burn out in normal use. Like @Stub Mandrel I use a couple of cores from any mains cable laying around most of the time, even 1mm lighting cable is plenty big enough. The reason speaker cables use thicker wire is to keep resistance to a minimum on longer cable runs. That's not relevant for the 40cm wire inside the cab.

Phil

 

Thanks for this. I did read an article that said AWG 4 (yep that's not a typo) should be used. Not sure I've seen anything that thick TBH. 
 

My AWG 16 will be fine then. I'll cut a bit off and solder it down. Does the cable need to be glued down to stop vibration at all? I'm assuming not but checking anyway. 
 

Thanks
 

Rob

[tauzero]

12 minutes ago, rwillett said:

Thanks for this. I did read an article that said AWG 4 (yep that's not a typo) should be used. Not sure I've seen anything that thick TBH.

 

I have in the past dismantled a GK 200MB combo, and the speaker wires on that are really thin - what I would think of as flexible hookup wire. And GK probably know what they're doing (although personally I wouldn't go for anything that thin, I use whatever spare mains lead is knocking around).

[Phil Starr]

1 hour ago, rwillett said:

Does the cable need to be glued down to stop vibration at all? I

Because most of my cabs never get truly finished I've a lot of loose wires in many cabs, and vibrating wires do happen but not often. I usually fix one end to the speaker itself with cable ties leaving enough slack to avoid stressing the connections but tight enough not to flap around. I bury the other end under any wadding and that stops that moving. I don't leave a lot of slack though, just enough to be able to remove the drive unit easily

Edited Tuesday at 12:18 by Phil Starr

[rwillett]

The weather here has slightly dropped off, however we have had reports of a bearded bloke collecting pairs of animals, and an awful lot of wood has gone missing. There seems to be some sort of structure being put up on the top of Ingleborough as well, no ones quite sure what's going on, but seems a dumb place to build a boat to me....

 

Anyway, I might get chance to do a bit more on the cab today after a week in London. I was thinking about a speaker grill and making sure I put some mounting points on, I rather like the metal grills that you can get on eBay. Is there a minium offset from the speaker that a metal grill must be, I look at the metal grill compared to speaker cloth and wonder does it either resonate or attenuate the sound.

 

Clearly people use metal grills and they look great, but wondered if they need to be 10mm (or another minimum distance) from the speaker or the holes need to be a certain size, do you need rubber mounts on them to stop them vibrating?

 

I can still put T-Nuts in if necessary for mounting points, even though the front and rear panels are now glued in, but I'd rather plan for it now than having to take it all apart again.

 

Thoughts welcomed.

Thanks

Rob

[Rosie C]

4 minutes ago, rwillett said:

Clearly people use metal grills and they look great, but wondered if they need to be 10mm (or another minimum distance) from the speaker or the holes need to be a certain size, do you need rubber mounts on them to stop them vibrating?

 

 

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.

 

[rwillett]

8 minutes 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.

 

@Rosie C Thanks for this, I had a feeling it was just my latest dumb question in a long trail of them. Pleased its not only me

[Chienmortbb]

On 09/12/2025 at 11:13, rwillett said:

My AWG 16 will be fine then. I'll cut a bit off and solder it down. Does the cable need to be glued down to stop vibration at all? I'm assuming not but checking anyway. If you look inside many commercial cabinets, will be shocked about how thin the cable is. 

 

WARNING NERDY CONTENT

 

Yes, AWG16 (use of AWG is deprecated) is approximately equal to 1.3mm2 , you look on t’interweb, you will find many tables showing the current rating of flexible cable, and they can vary considerably.

 

https://www.cablejoints.co.uk/upload/AWG--American-Wire-Gauge--To-Metric--Sqmm-Millimeters-Squared--Conversion-Table.pdf

 

The reason is that many of them are quoting for different uses, high temperature, enclosed in conduit/trucking etc. These things reduce the current rating. In addition they usually quote for a single conductor, Free air or strapped to a cable tray, those perforated, overhead strips you can sometimes see in shops and factories. 
 

When using flexible copper cable to connect between an amplifier and a speaker remember that the cable ratings in these tables is continuous whereas a music everything is along away from continuous (of course most recordings from after the 80s do not qualify as Music). 

The other thing you need to remember when you’re looking at the cable current rating is that the power you can draw through a cable is determined by the impedance of the load. An 8 ohm  load will draw twice the current of an 4 ohm load. So:

 

Let’s take a cable rated at 6 amps. Power is current (squared) x Impedance. 
 

6x6=36 then 36 x 8 = There 288 watts. 
 

For 4 ohms it is 36 x 4= 144 watts. 
 

The irony of that is many Jacks and plugs are rated at 5 amps or less. 

Finally the reason for using what seem like crazy large cables for speakers should not be looked at purely for current rating. Thicker cable means lower resistance (although cables exhibit some capacitance and inductance, they can be ignored) especially over short lengths). A cable that is too thin can  consume some of your power, especially when running 4 ohms. 
 

Thin cable, what those across the pond call hook-up wire can have a resistance of 2 ohms per metre. Of course a 50cm, 2 core speaker cable has 1 metre of cable. So 100 watts of power into a 4 ohm speaker could lose up to 33+ watts in the cable leaving 66+ watts for your speaker. 
 

Go up to a 2.5 mm2 and you would lose less that 1/1000th of a watt at 100 watts. 
 

You must also remember that both the cable in the cab and cable between the amp and cab need to be added to give an accurate resistance/impedance figure. 

[Obrienp]

So if you have a driver rated 600watts @8 ohms, does that mean you need to be using something like AWG 12, or 10?

[LawrenceH]

1 hour ago, Obrienp said:

So if you have a driver rated 600watts @8 ohms, does that mean you need to be using something like AWG 12, or 10?

No need, the resistance of even 1mm2 copper core is less than 0.02 ohms/meter. And as John says the amp rating for cable is based on continuous, sustained current. That means running it at that rating for long enough that it reaches temperature equilibrium, and failure mode is by melting the insulation. You just wouldn't ever reach anything near that in a speaker.

 

Given that flexibility isn't that useful or desirable inside a speaker, I just use offcuts of T&E after tripping off the outer insulation

[nekomatic]

2 hours ago, rwillett said:

Clearly people use metal grills and they look great, but wondered if they need to be 10mm (or another minimum distance) from the speaker or the holes need to be a certain size, do you need rubber mounts on them to stop them vibrating?

The speaker specs will tell you the maximum cone excursion, Xmax, which for this driver is 5.5 mm. Sometimes they give a separate larger figure for the excursion where damage will occur, but I think if we go past Xmax that means we’re into the realm of abusing the speaker anyway. So the cone should move at most 5.5 mm forward (or backward) from its rest position, add a couple of mm for (waves hands) stuff, and I guess that should be fine. 
 

I don’t think the size of the holes matters acoustically, but guess the percentage that is hole rather than not hole might do? I’d say picture what a speaker grille usually looks like and go for something not too different from that. 
 

You want to avoid the grille vibrating too much at an annoying frequency, so I would probably mount it as rigidly as you can. I screwed mine to blocks round the edge of the baffle and one in between the speaker and port and that seems fine. 

[tauzero]

3 hours ago, rwillett said:

Clearly people use metal grills and they look great, but wondered if they need to be 10mm (or another minimum distance) from the speaker or the holes need to be a certain size, do you need rubber mounts on them to stop them vibrating?

 

I used perforated aluminium sheet with 3mm holes on the Plenty cab. While it pumps out a respectable volume of sound, I suspect that the resistance to fluid movement caused the fixing screws to ease off slightly so it sounded as if the speaker was on the way out on a recent open mic night. I took the grill off to check and it was fine, so I put it back on and tightened the screws firmly and it's still fine. However, for the 8" cab, I'm using 10mm diameter hole perforated sheet, and I may well retrofit the Plenty cab with it too.

[3below]

46 minutes ago, LawrenceH said:

....... Given that flexibility isn't that useful or desirable inside a speaker, I just use offcuts of T&E after tripping off the outer insulation

 

2 hours ago, Chienmortbb said:

The irony of that is many Jacks and plugs are rated at 5 amps or less. 

 

 

Just had a quick look on the back of my Peavey Tour 700  which claims 700w rms @ 52.9 V rms.  Quick calculation gives Irms =13.2A.  I just use offcuts of mains cable, perfectly adequate   I also use Speakons.

Edited 5 hours ago by 3below

[rwillett]

Thanks for the comments.

 

So the Fane speaker is 11mm high from the front of the baffle. It has a maximum excursion of 5.5mm and I've just measured it and that maximum excursion is inside the 11mm rim around the outside of the speaker, so that's good.

 

The outside edge of the speaker cabinet is about 27mm (or so), so that gives 16mm (or so) space for the grill (or cloth or whatever). Just looked up 10mm perforated aluminium and it's 1mm thick, so I have quite a lot of leeway for mounting it. It could 2-3mm inside the outer edge to stop it catching and that still leaves it 12mm or so away from the speaker. 

 

I think that answers the question as does @Chienmortbb's comprehensive reply on speaker cable width. I really, really wish we could throw away every non-metric measurement. 1.5mm^2 cable is easy to understand, a reverse sized number is just confusing. I am a child of the metric system (just).

Rob

[tauzero]

17 minutes ago, rwillett said:

I really, really wish we could throw away every non-metric measurement. 1.5mm^2 cable is easy to understand, a reverse sized number is just confusing. I am a child of the metric system (just).

 

We have been a purportedly metric country since 1963. There really isn't any excuse for hanging on to imperial measurements (the very last vestige of British empire), only officially used by three pretty much third world countries - Liberia, Myanmar, and the United States.

[3below]

55 minutes ago, tauzero said:

 

We have been a purportedly metric country since 1963. There really isn't any excuse for hanging on to imperial measurements (the very last vestige of British empire), only officially used by three pretty much third world countries - Liberia, Myanmar, and the United States.

Whilst I agree with this in principle there are some practical difficulties. SI units made my professional work much easier (physics - and I am old enough to have used Imperial, cgs, mks and SI) I am now on what will be my last big project, 1780s house restoration. Everything is Imperial (or somewhere close, i.e. whatever was to hand). There are some metric equivalents but also many features that have to be made to size.  My working knowledge of Imperial is still useful.

[Mottlefeeder]

1 hour ago, rwillett said:

...So the Fane speaker is 11mm high from the front of the baffle. It has a maximum excursion of 5.5mm and I've just measured it and that maximum excursion is inside the 11mm rim around the outside of the speaker, so that's good...

 

The 5.5mm is Xmax not Xlim.

The first is the excursion while staying in the magnetic gap (ie controlled and low distortion), and the second is the excursion to the point of damage.

Your speaker cone is capable of moving way beyond Xmax.

David

[Stub Mandrel]

Basschat 203.2mm Cab Design just sounds soooo wrong!

I'm bilingual, not only can I work in Metric and Imperial, but I can visualise both as well. Imperial is really convenient when you need things in different sizes with good proportions and need to allocate dimensions into convenient subdivisions. Metric has it's preferred sizes, which can be OK for proportion, but are a nightmare if you are adding different sizes and trying to get to a convenient overall dimension.

 

[Balcro]

4 hours ago, rwillett said:

 

I think that answers the question as does @Chienmortbb's comprehensive reply on speaker cable width. I really, really wish we could throw away every non-metric measurement. 1.5mm^2 cable is easy to understand, a reverse sized number is just confusing. I am a child of the metric system (just).

Rob

 

 

For an ancient like me who learnt imperial in 1953 and moved on to metric in the 1970's, what does the ^2 mean? Metric numbers and volumes etc are OK, but these weird "new maths expressions" are just confusing. They look like a change for the sake of change!  

 

Edited 1 hour ago by Balcro

[rwillett]

39 minutes ago, Balcro said:

For an ancient like me who learnt imperial in 1953 and moved on to metric in the 1970's, what does the ^2 mean?

 

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.