Stevie’s 12” FRFR Cab Build Thread (Basschat Cab v3)

[stevie]

Well thank you all very much! It's true that a number of Basschatters have provided valuable input that has made it possible to give birth to this cab, and I have tried to mention everyone along the way. However, at this juncture, I think a special vote of thanks is due to Pete (funkle).

A cabinet building beginner by his own admission, he has worked under the glare of public scrutiny to draw our attention to the mistakes that lie in wait for the unwary - by making those mistakes on our behalf.

Not only that, but the descriptions and photos in this thread provide an excellent guide for those who will follow in his footsteps.

Now, about those T-nuts.... 😀

Edited September 9, 2019 by stevie

[stevie]

21 hours ago, LukeFRC said:

It was designed to sit top right - I think an inch from each edge of baffle gave enough clearance of the port that @stevie was happy.  Obv adjust to taste based on what you think and what looks good! 

 

Talking of which - I kept my sticker rather than post it to you Stevie to post it back - you will have to let me know my number

Yes, top right is where I'd put it - sorry Stew. Definitely not top left because that will alter the frequency response of the horn. Its presence above the port is unlikely to have any effect on what's coming out of the port.

You could always try it on the bottom or centre if you like.

By the way, the badge doesn't look blue as in funkle's photo. The background is very dark blue, almost black.

Given your contribution to this project, Luke, I think you deserve to have serial no. 002. It's yours.

Edited September 9, 2019 by stevie

[stewblack]

I wish I could have contributed in a practical way to this incredible project. As it is I have nothing but respect for those who made it possible. 

[LukeFRC]

2 hours ago, stevie said:

Given your contribution to this project, Luke, I think you deserve to have serial no. 002. It's yours.

2 is my favourite number.

[LukeFRC]

2 hours ago, stevie said:

By the way, the badge doesn't look blue as in funkle's photo. The background is very dark blue, almost black.

Technically I think it's a rich black erring towards blue as I was trying to get as much pigment into the sublimation process as possible to be dark enough, but not have the risk of it going odd colours browns or something under stage lights.

It will er towards a blue but in a way that won't look odd on stage, and contact the red. 

[stevie]

1 hour ago, LukeFRC said:

2 is my favourite number.

Good job you mentioned it then. 🙂

[funkle]

Ok, I managed some bits and bobs today. 

First of all, I put the woofer foam in. No photos, but it was an easy job now that I know how to handle T-nuts with care 😂

Secondly, fitted the grille foam surround. My tips for this are: cut it long (it’s stretchy so will go even longer than you cut it, but better being safe), and when sticking it down, only peel off the backing for the section you’re working on. It’s very unwieldy and sticky otherwise.

Tidy job after though. 

Whilst I await the badge tape, I decided to screw the grill in. @stevie gave some helpful advice for this:

1. Screw in the four corners first

2. I’d likely need two more screws along the vertical and one more along the horizontal

3. Make sure as much grille material is caught underneath the screws. Relevant here as the open ‘cell’ structure isn’t always completely closed on some sides of the grille. 

Now, @stevie sent me some more foam to stick on the top of the woofer to support the grille in the middle of it. I tried that, and it poked through and looked unprofessional. I removed it. 

In this case, with this grille, I think it is not required; it turns out the built-in foam on the front surface edge of the woofer sits proud of it. (There’s also plenty of space between the grille and even the foam edge of the woofer. It’s not a good idea to have the grille supported by the foam edge.)

So, after all that, here’s the screwed in grille:

I like it. It all blends in.

I need to play this more tomorrow. I’m itchy right now to...lol....but kids are asleep. 

Grille weight by the way was 650g, or 1.433 lbs. 

Total cab weight is 29.8 lbs. Beautiful. (Nearly the same as a Barefaced BB2, which uses a much more complicated build to get its weight - 29 lbs.)

Killer cab.

Edited September 10, 2019 by funkle

[LukeFRC]

1 hour ago, funkle said:

it turns out the built-in foam on the front surface edge of the woofer sits proud of it, and can support the grille itself if need be. I think it’s an intentional design feature of the Faital; subtle but helpful. 

isn't that so it works if mounted to the rear of a baffle? That's what I had always imagined

[funkle]

35 minutes ago, LukeFRC said:

isn't that so it works if mounted to the rear of a baffle? That's what I had always imagined

It would work that way if mounted to the rear of the baffle, indeed. 

[Phil Starr]

I think you'll find the foam is only 5mm or so thick, less than the movement of the cone Xmax is 7mm and Xdamage 17mm I think.

[funkle]

55 minutes ago, Phil Starr said:

I think you'll find the foam is only 5mm or so thick, less than the movement of the cone Xmax is 7mm and Xdamage 17mm I think.

I had been contemplating that. There’s still a gap between the grille and the front edge of the foam; perhaps I should have said that when I press down hard on the grille, it can touch the front edge of the foam. (That was before I fixed it in with screws.)

Hence, additional foam seems unlikely (I hope) to be needed, as well as being unsightly when it is placed.

If the driver is regularly hitting the grille, then there’s only one of a few problems it will turn out to be. 

1. The grille is too close for ordinary playing. In which case, the battens should be a larger depth, or the baffle depth needs modified, or we need a grille with a slight stand-off, or the front edges of the cab need to be deeper and the design tweaked overall.

2. I’m abusing the woofer by taking it regularly to Xmax and beyond. The problem is the user...

If I find the woofer hitting the grille regularly with ordinary playing, then I might add more foam around the edges to the battens, to increase the distance. Hopefully it should not be necessary. 

Edited September 10, 2019 by funkle

[Phil Starr]

I don't think you'll have a problem, Stevie will have specified the batten's you used to support the grille to keep it well clear I think they were 20mm that you used?

The 17mm is the point where the voice coil comes right out of the magnetic field and I doubt you will reach that point in practice. the distortion wouldn't be very nice either. All I was worried about was that someone reading this would think the foam on the speaker was there as some sort of protection. It isn't. 

Folks, you need the grille well clear of the speaker. 15mm is probably minimum for a bass speaker and that doesn't allow for any bending or denting of the grille over time.

Edited September 10, 2019 by Phil Starr

[stevie]

I've just measured up. The distance between the highest point of the cone and the top of the foam surround on the chassis is 5.5mm. The gap between the top of the foam surround and the grille is 4mm. So, the cone can travel 9.5mm before is just starts to touch the grille. 

If this were a problem, the solution would be to to move the grille further away from the driver using thicker foam on the picture-frame support, as Pete suggests. Or try to find some 11 x 19mm batten, although I don't think that's a commercially available size. As it stands, if the cone is audibly hitting the grille, it's a sign that you're about to wreck the driver.

The above calculations only work as long as the  grille remains flat. If it sags in the centre, you'll lose some clearance. That's why I like to provide an additional support for the centre of the grille. You'll see a central support in commercial bass cabs too, usually just a screw and a washer through the grille into the cab. It's very unlikely that this grille will sag in the middle unless it's pushed in. The purpose of the central support is to prevent that from happening.

The foam strip that Pete referred to earlier was supposed to go on the top of the chassis to push the grill out slightly and hold it there. The trick works really well and is invisible in practice on most types of grille, but the one Pete is using is quite open and I can see that it would look odd if it pokes through.

Edited September 10, 2019 by stevie

[Phil Starr]

I don't think there is a problem, the only bit that would touch would be the outside of the cone. That is nearer the fixed outside edge of the grille so a 10mm distortion of the grille in the centre might only be 3mm near the edge of the cone, that would be quite a big dent!

My only worry was that someone reading Pete's account might think it a good idea to rest the grill directly upon the speaker mount.

[stevie]

6 minutes ago, Phil Starr said:

My only worry was that someone reading Pete's account might think it a good idea to rest the grill directly upon the speaker mount.

Agreed - that wouldn't be a good idea.

[funkle]

3 hours ago, Phil Starr said:

I don't think there is a problem, the only bit that would touch would be the outside of the cone. That is nearer the fixed outside edge of the grille so a 10mm distortion of the grille in the centre might only be 3mm near the edge of the cone, that would be quite a big dent!

My only worry was that someone reading Pete's account might think it a good idea to rest the grill directly upon the speaker mount.

Good point. I’ve edited my post to make sure everyone knows that that is not a good idea. 

[stevie]

19 hours ago, funkle said:

Grille weight by the way was 650g, or 1.433 lbs.

The aluminium one (shown in the parallel thread) weighs 400g.

[funkle]

It’s done. The badge is the final touch, and the strong double sided (slightly foamy) sticky tape is holding well.

(Link for tape at https://www.amazon.co.uk/dp/B071ZYRKQS)

The angle I took it at makes it look like the badge obstructs the port a little, but it doesn’t. 

I’ll take some final glamour shots tomorrow in daylight. 

I’ve been playing it a lot, and although speaker ‘break-in’ is very likely a myth, I played a looped bit of bass from my Zoom B3 looper through it for a few hours as well anyway. 

I really like the sound of this cabinet. Tomorrow I’m going to try a lot more fx through it. 

Look ma, I made a black box. 😂

Edited September 10, 2019 by funkle

[stewblack]

20 minutes ago, funkle said:

It’s done. The badge is the final touch, and the strong double sided (slightly foamy) sticky tape is holding well.

(Link for tape at https://www.amazon.co.uk/dp/B071ZYRKQS)

The angle I took it at makes it look like the badge obstructs the port a little, but it doesn’t. 

I’ll take some final glamour shots tomorrow in daylight. 

I’ve been playing it a lot, and although speaker ‘break-in’ is very likely a myth, I played a looped bit of bass from my Zoom B3 looper through it for a few hours as well anyway. 

I really like the sound of this cabinet. Tomorrow I’m going to try a lot more fx through it. 

Look ma, I made a black box. 😂

Bravo! And thanks again for sharing your experience 

[VTypeV4]

Fantastic - everyone involved should be proud of this! Well done guys. 😀

[Chienmortbb]

I feel I should add my comments to this. The original 1x12 project was started by Lawrence, Phil Starr and Stevie and made an excellent single 12” cabinet. 

I came to the project late, and offered little ,but hopefully helped by building the first prototype for the Mk2. I then built one of two (Stevie built the other) Italian Poplar cabinets, mine loaded with the Beyma  SM212 plus Celestion 1415 compression driver and P Audio horn. I gigged that Cabinet for two years until the lighter Faital Pro driver became available.

While the road to the CNC Kit Mk3 looks smoother than the final cabinet’s frequency response, the road to getting here was far from smooth.

There were many cold days spent in Stevie’s measurement room fine tuning various combinations of driver. There was also comparisons to many other drivers and commercial cabinets and I was present for only some of these sessions.

Stevie did many on his own, often in the depth of Winter.The measurement room is in a cast  concrete garage and whilst well fitted our for measuring cabinet response, it it not the warmest room in the depths of Winter.

The big change from the MK1 was the single large port that proved to be less prone to chuffing than multiple ports. Like many of the improvements, the large port makes little difference at lower volumes and Phil had gigged his Mk 1 cabs with four ports for a couple of years without hearing chuffing, until under test conditions. However it allows the 

British Cycling have used the concept of marginal improvements to put Britain top of the cycling tree and Stevie did the same with the MK2/3. Tuning the response to a true FRFR response was only part of the story. The real genius for me was rotating the horn. Although it looks a little odd, it gives more of the mids to the player when standing directly in front of the cabinet. Compared to me Mk2 with the horn horizontal, The MK3 , with the vertical horn, allows you to hear yourself however close to the cab. At 30cm/1ft, the Mk3 is easier to hear than the MK2 at 4-5ft/120-150cm. This is ideal if you are on a tight stage. 

I look forward to Funkle’s input as he uses the cabinet but I will be surprised if he does not love it. 

 

Edited September 11, 2019 by Chienmortbb

[funkle]

I’m already enjoying it. Really fun to experiment today. Turns out I like a little bump around 80-100 Hz in there, at least for Fender style basses. Lower than that works but introduces mud into the room I’m trying it out in, much as you might expect.

I also really like simulating a B15 through the cab. If that doesn’t give you an ironic laugh, nothing will, lol.

Seriously though the Fishman pre built into the Zoom B3 is very good. Adjustable HPF, and an adjustable ‘mid’ control that lets you dial right down to 40Hz...so you can really play around with frequency boosting/cutting very specifically.

I ran some distortion into the cab and liked it, although I think compared to other cabs some treble EQ is needed to help manage it down a little. But the B3 again works great for that. 

I really dig this cab. Every note is clear and EQ is a pleasure to use. It sounds even but still like a bass cab. 

Edited September 11, 2019 by funkle

[LukeFRC]

So I’m getting excited seeing @funkles build and been planning my own. 

One of the provisos that my other half put on me having another “box” was it had to look as nice as my Mesa walkabout- that’s a green tolex, brown leather corners and handle and tan basket grill. While I could have just copied it I decided to go for another colour, like Stevie I’m going to mix my own Tuff Cab - combining turbo blue and black to get a dark blue (coincidentally not far from my bathroom wall colour in the background of the pics)

for the grill I’ve got a tan coloured fly screen. Over 50% open and hopefully opaque enough not to look stupid - if it does I’ll pick up some black stuff and try that- it’s proper tough stuff so will be able to get it quite taught. 

For the leather corners there is a shop in our village called scrap, that sells erm scrap stuff for craft type projects. There is a bit of an ever changing range of leather offcuts from a local leather producer or user. I managed to pick up a couple of options for a brown - and also a light teal blue which might be quite fun. (Though crying out for a matching colour aluminium grill) 

[stewblack]

I am toying with the colour scheme for mine too. One idea is to get a little green in there - homage to my beloved Trace Elliot heritage. Maybe mix the paint to get a deep greenish black. I have several old TE grills I could use - assuming they would fit. 

There is also a company that produce bespoke speaker cloths which gives unlimited scope. One for each day of the week if you wanted!

Above all I shall be clearing space in my tiny gear store as I think this could be a cab for all seasons. Other bigger boxes will go. Although if I enjoy the build maybe the boxes could go but the speakers might get new home built enclosures. 

Anticipation is building. 

 

Edited September 11, 2019 by stewblack
typo

[LukeFRC]

8 hours ago, stewblack said:

Maybe mix the paint to get a deep greenish black.

You won’t need too - they make two dark greens