stevie

As I explained to Jon in an earlier post, there isn’t a problem with the port length. Also, a 4-inch port isn’t too large for a 10-inch driver – that’s just a completely weird assertion. As far as port nonlinearity is concerned, the number one priority (by far) is maximising the size (and optimising the shape) of the port. The maximum vent air velocity in the cab at its rated output is currently about 14m/sec/Hz, which is very good and I dare say better than virtually any commercially built small bass guitar cabinet. Reducing the area of the port would mean going to a 3-inch port, which would nearly double the vent speed. In fact, 80W through the 3” port will take the vent air velocity to the same level that the 4” port experiences at 200W. Although most bass guitar cabinet designs would actually meet the two-to-one ratio requirement, it is purely arbitrary with no real basis. Try designing a compact subwoofer with those constraints in place and you won’t get very far. In fact, you can make a port as long as you like as long as you know how to deal with the trade-offs. We’re using a 100mm diameter port 170mm long. So that’s all right then. 🙂

You're making some good points. The gap between the end of the port and the back panel certainly matters but the rule you mention applies to slot ports. If you have a full-width slot port, you should leave a gap equivalent to at least the height of the slot port between the end of the port and the rear panel of the cabinet. Otherwise, you’re constraining the air flow into the port, which will speed it up and cause turbulence. Designers have been trying for decades to find ways of reducing turbulence in ports – so this is the last thing you need. Round ports are different. You can go closer than the diameter of the port. The main thing is that the flow of air into the port isn’t constricted. You need to visualise it and use a bit of basic geometry. On your speaker you should have about 40mm of space behind the port. That’s fine. You could actually go closer than that without restricting the air flow. Nice work, by the way.😊

Tickets £5.98 incl tax? I can't believe it. Get touring!

Or south west England?

Scarily good!

I think Phil designed this box to be 30 litres net - or about 34 litres gross. WINisd probably deducts the volume of the driver and port from the total - my software does this. Also, and without checking, it's quite possible that the internal diameter of the 100mm port is something like 97 or 98mm internally. I only used modelling software to prove the concept and did the tuning on the box itself. You'll find the impedance curve showing the tuning frequency a few pages back in this thread. As others have pointed out, you have to be very careful with xmax, as there are different ways of calculating it. I tend to use coil length and xlim as my yardsticks nowadays. The three power-limiting factors - thermal power handling, excursion and vent speed - are nicely balanced in this design, which should work well with a 200W amp.

German Schlager of the 1970s probably represented the nadir of Western popular music.

Lol. He also recorded this. If you can listen to more than 10 seconds, you're a better man them me. It's a youthful version of Heino's ditty you posted earlier.

It's worth repeating that the on-axis frequency response of the bass driver, whether it's a 12 or an 8, is less relevant than you might think because you hardly ever listen to a bass cab directly on-axis. When you're standing above or to the side of a cab, the midrange and HF frequencies are greatly attenuated. The horn in this design crosses over at 2kHz (more than an octave lower than most commercial designs) to compensate for this and allow you to hear those mid and high frequencies clearly - even when you're above and to the side of the cab. Also, if you're playing without PA support, what your audience hears is not the on-axis sound from your cab but the 'power response' or the sum total of the speaker's radiated output. This is why live bass often sounds dark and murky with no energy even if a cab has a tweeter.

The Pulse 15 is probably the best Celestion bass guitar 15. The BN-400X is underdamped. This will boost the frequency response around 80Hz in a normal sized bass cab, making the cab appear to have oodles of bottom end. In practice it's not conducive to a great bass sound IMO. Put the Pulse 15 in a cabinet with an internal volume of 100 litres. Fit two 100mm ports, 112mm long or (better) a 150mm port of the same length. That will tune the cab to 45Hz, which should be fine for 5-string bass.

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. 😊

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..

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.