stevie

The PDF plans are attached to the first post in the thread. Unfortunately, we lost all the photos of the initial builds but I reposted all the later ones showing the cabinet build process in detail. Also, check out funkle's build thread, which also contains useful info.

The 12FH500 is a very nice driver - I've got some 12FH520s in my workshop. It sounds a bit leaner in the bass than the 12PR320 but it's very well defined. Unfortunately, its midrange response is different, which means it would need a crossover redesign to get the best out of it.

It's a shame there's such a delay with the horns. If I'd known, I'd have specified something that's more readily available. The horn's integral to the design, I'm afraid. Fitting another horn is possible but would also require a different crossover.

That's an excellent idea, @Stub Mandrel. At £3 a pop, it's hard to go wrong. The stuffing is made from recycled plastic bottles and is used in a number of acoustic products - so eco-friendly too. The only question is whether the material is self-supporting, like sheets of BAF wadding, or whether it's loose fill, which would be difficult to fix down inside a cab. 

I'll buy one next time I pass Morrisons and report back.

The easiest way to do this is to build a second cab without an HF unit or crossover. Then link it to the full-range cab in the normal way. A second HF unit isn't helpful because you'll get phase-induced constructive and destructive interference between the two units (comb filtering).

Isn't this a guitar cab? If it were mine, I'd be making sure it'll handle bass at more than bedroom level.

When I fitted the MM pickup to my P/J, I had already tried a number of different Jazz pickups, but they all sounded weedy in that rear position. OK if you play like Jaco, but I didn't find any of them very usable, even in combination with the P.

I replaced a rear Jazz pickup with a MM and it worked really well with the front P-bass pickup, giving you two distinctive sounds to choose from.

As has been mentioned, it does require a bit of routing. And you need to wire the MM pickup in series to match the output of the P pickup. It's a great combo though.

His output is prodigious and I don't agree that all the songs he thinks are great really are great. although some of them are. But just check out the video I linked to. I'd be astonished if you didn't like it.

Like many of you, I've been following a number of music educators on YouTube - some of them, like Aimy Nolte and Adam Neely have been mentioned on here. But Rick Beato's latest video, in my opinion, is  in a class by itself. Not to mention hilarious in places. 

Once you've watched this, I suggest you have a look at this cover:  

Then look up Barry Mann and Cynthia Weil and be astonished at the brilliance of this songwriting team. Just as a taster, they also wrote the world's most played song, You've Lost That Lovin' Feeling. My admiration knows no bounds.

Not only that, but he's probably still trying to figure out what 'give over mate' means. 😊

I've got one of these as my one and only bass and don't expect to find anything better.

While it's true that clipping your power amp will dump lots of high frequencies into your tweeter, this doesn't seem to be what's happening here, as the problem exists at low volumes.

There are too many variables to troubleshoot reliably, but the cause might be:

1. The system is reproducing what it's being fed and the Ashdown distortion isn't very nice or has been voiced for a non-tweetered cab (no HF rolloff)

2. A 2nd order filter at 3500Hz isn't steep enough for the APT 80 and you're hearing distortion from the tweeter below the crossover frequency. 

As @Chienmortbb rightly says, you'll probably find it easier to troubleshoot using a good recording of voice.

Nice one! I love a good head-to-head done well. Lakland for me. The individual notes were more defined. The Jazz tended towards muddiness in comparison..

On 01/06/2021 at 12:57, Jolltax said:

More dumb questions! Went to my carpet place to get underfelt and they say they don't really use felt any more but have this stuff they use when they are installing underfloor insulation?

 

Do I need to extend the length of my tubey port thing, what does a baffle brace look like?

Its sunny today so I'm off outside to start cutting holes and stuff!

J

 

That doesn't look like the kind of felt that works in loudspeaker cabs. You could use this: http://www.bluearan.co.uk/index.php?id=TUFFWAD14A

which is the stuff they use in duvets, pillows and sleeping bags. The original eBay felt supplier now has a minimum order of 15 metres, which is a shame.

Yes, you'll need to lengthen the port by 2 or three inches. The easiest way of doing it is with some card. Roll it round the end of the plastic port and attach it with duck tape of similar. Just make sure it can't rattle.

Sure, it'll work. But the alternative is to sell what you have and buy something else that will do the job you want. Is that hard to understand?

Yes, that's the usual advice on this forum. "I have a cab that's inadequate and not loud enough. What to do?"

"Buy another inadequate cab. That'll fix it." 😀

I'm not saying that this is necessarily bad advice, but there are other options, like replacing the cab with one that'll do the job.

I have a spare you can have for the cost of postage. I could get it off to you at the weekend.

😁 Just a little sideline of mine..... As I have all the equipment and the know-how, I help speaker builders out by custom winding hard-to-find inductors at very reasonable rates. It's not going to make me rich, but it's very satisfying.

There's no standard formula for crossovers done properly. I've published quite a few on here and they've all been completely different. You have to use the components and circuits that work for the particular drivers and cabinet you're working with. It's like making a bespoke suit or designing a website.

However, like most things in life, it's possible to bodge. The 2nd order LP and third order HP is based on the idea that you don't want two lossy inductors in the path to the woofer if you can help it, and you need to use a fast rolloff to protect the tweeter. There's a lot more to it than that.

1mm or 1.2 mm for the bass inductor.  .7 or .8mm for the .5mH value and .6mm for the 1.1mH value inductor, although thicker wire won't do any harm if your choice is limited. Resistors should ideally be 20W. I'd also double up on the resistors in the LF circuit, i.e. 2 x 2.2 ohms for extra power handling. Don't bother with esoteric capacitors. They're a waste of money IMO. But do use film type caps and not electrolytics.

Inset handles are a good idea, as that existing handle makes it awkward to put an amp on top. I don't understand why you'd want one on the bottom though.

You can indeed fit bracing retrospectively as Phil suggests, although you'll probably not need quite as much as in the Basschat design because you're working with heavier and thicker material. A central figure 8 brace is always a good idea to start with. Then it's suck it and see. I suspect you'll need a vertical brace on the back panel behind the driver and a vertical brace between the horn and the port on the baffle. 

I'd advise against using carpet inside the cab. It's relatively heavy and not very effective. Carpet felt underlay is good - I use that for some things - or the usual BAF wadding, which is the kind of thing you find in duvets or sleeping bags. Don't put any within about six inches or so of the port.

Looking good so far!

There are plenty of examples of commercial speakers that use a driver's natural rolloff as part of a crossover. I'd mention the Spendor BC1 as just one example. That used the natural rolloff of the Celestion HF1300 to *cross it over* to a Coles supertweeter. It wasn't very elegant, but it worked.

As far as bass cabs are concerned, using a properly designed two-way crossover is a much better solution, but nobody does it because it costs money and doesn't add to the perceived value of the product for the average punter. 

You can indeed buy ready-made crossovers but I'd compare them to having your hair cut with a pudding bowl. Yes, it's a haircut and some people might even like it -  but nobody's should believe it's a proper haircut.

A 'proper' crossover needs to be designed for the drivers (and cabinet) being used. Unfortunately, just about every bass guitar cab I've seen has a minimalist crossover like the one @Killed_by_Death showed earlier - because it's cheap and nobody seems to care anyway.

The impedance the amp sees is a combination of the crossover and the driver. If you'd like a solution that's been tested and documented on this very forum, check out the Lockdown cab build thread. There, you'll find an inexpensive but very good compression driver/horn combination along with a cheap-to-build crossover that was originally designed for use with a Celestion 10 but won't be a million miles out if used with another bass driver. 

Very good question. The answer is that you're quite likely to have impedance issues unless you know what you're doing. Here's an example of a commercial cab with serious problems in this area. It's not the first one I've seen either.