Bill Fitzmaurice

Even worse, multiple sources playing low frequencies may cancel each other. Besides, what you don't need from monitors is lows. You need mids and highs, especially if your backline isn't aimed at your ears and the mids and highs from it are passing you by below the belt.

1 hour ago, Jaybeevee said:

Thanks, that's something new for me. Unfortunately, not supplied with a manual, and the manufacturer is not answering me specifically on this point.

You can find third party sources for manuals for most amps. Google ' *** amplifier manual'.

It depends on where the lamp is wired to the circuit. Clipping can take place at every stage of amplification, from the input to the output. The manual should say. In general minimal clipping takes place when the master is on full, with the pre volume low.

The only people with any interest in your rig are other bass players. 😉

Aside from an old spare for emergency use, which of course I've never had a need for, I've never had more than one amp. You'd think I'd have a shed full of speakers too, but I don't. I've never had more than two on hand, most of the time only one. I've never owned more than one bass at a time either. The one I have now I made 25 years ago. I'm comfortable with what I have.

He may, he may not. When I do my initial sound check in a smaller room without major PA support I do it from out on the dance floor, adjusting my volume and tone for the best result there. Whatever that ends up sounding like on stage I live with.

Functionally a send and an active DI should be essentially the same. They may differ in whether they're pre or post EQ. The amp block diagram would reveal that. 

At the very least either lift the cab or tilt it back to aim the drivers as close as possible to your ears. One of the reasons why the 8x10 gets so much love is its height allows you to hear the mids and highs.

Google 'boundary sourced low frequency cancellation'. You get it when you're close to boundaries. It goes away when you move away from them.

On 17/01/2023 at 09:25, Mykesbass said:

I'm sure one of the speaker experts on here will correct me if I'm wrong, but my back of an envelope calculation shows that the surface area of the PJ cabs is very small - a couple of 112s will be significantly larger and give you a lot more movement of air.

That. The cone area of a five inch cone, Sd, is around 100 square cm. Four of them is around 400 square cm. An average twelve is 530 square cm. Just as significant is the excursion limit, xmax, which combines with Sd to give displacement, Vd. Vd defines how loud a driver may go. An average five inch Vd is 50cc, making it 200cc for four. An average twelve Vd is 300cc, a high end twelve Vd is 500cc.

There are a number of other factors which impact how low a five can go. They can go as low as larger drivers, but to do so they sacrifice sensitivity, which means less output per watt of input. I'm a big fan of fives myself, in the right context, which IME is as a midrange driver used in conjunction with a larger woofer.

6 hours ago, fretmeister said:

Silly question about gauges. I see on some sites that a chunky gauge should be used with amps that are about 1000W, but up there ^ 18 gauge has been suggested as ok. So what's the deal? And why do some sites use mm measurements rather than gauges?

You need sufficient gauge to handle the current without overheating and not cause voltage drop. At 1 meter it doesn't take much. Wire gauges are typically used in the same locales that use inches and feet, mm where they use metric, for the same reason. This is a must read if you don't know anything about cables. It's aimed mainly at the hi-fi crowd, as they tend to be more easily scammed by cable mountebanks than professional musicians, but the physics still apply. http://www.roger-russell.com/wire/wire.htm

I have no issue with buying rather than making your own, even though it's a ten minute job. But at least buy something that's reasonably priced, twenty quid tops. The reliability factor is determined by the quality of the connectors. Those I linked from Blue Aran are as good as it gets.

28 minutes ago, three said:

 Amazon have the EA Siren 3' at about £72

That's an insane price for a one meter cable. As for all the claims they make, they're piffle, the entire lot. A pair of these, along with a meter of zip cord from a local hardware store, is all you need. https://www.bluearan.co.uk/index.php?id=NEUNL4FX

Just be sure to get Neutrik, not an imitation. The knock-offs have been known to cause problems.

Quote

So I could order the parts and then have to find some time to assemble it and then be paranoid that I’ve done it wrong and I’ll cause a fire or something,

You're a bass player. You're supposed to be the smart one in the band. 🙄

When you've got four identical woofers sharing the same airspace you're not going to get a significant difference in response from each pair even if you were to bi-amp them, let alone dual amp.

The BN10-200X is displacement limited to 120 watts, so a 500w/8 ohm amp would have no problem driving four of them to maximum output. If you can't find one rated for 2 ohms rewire them to series/parallel for 8 ohms. BTW, you didn't bi-amp if you didn't have an electronic crossover. You were dual amping.

You might not need as much power as you think, nor dual heads. I may be able to confirm it knowing what drivers you have.

Actually it's small, low and sensitive. Money does enter the equation, as longer xmax drivers capable of going low in small boxes tend to be more expensive, but they still can't get around the sensitivity, so to go loud requires more power, which means a more expensive amp as well.

1 hour ago, Balcro said:

The BN300S that Bill mentioned is 4-5 dB louder than the Celestion Pulse 12 from 400Hz & upwards, but the Pulse has a very strong thump around 80-140Hz - see Celestions' own frequency response graphs.

That has nothing to do with the magnet material. A higher Fs and other factors give the BN300S higher sensitivity in the mids, but also result in less low frequency extension. One of the highest sensitivity drivers ever made was JBL D130, which had an AlNico magnet. It also had very poor low frequency response, but that was an acceptable trade off in 1948, when 25 watt amps were state of the art. It was also designed some 17 years before the advent the Thiele/Small specs. Only after that did designers realize that the main way to get higher sensitivity, more magnetic flux, doesn't increase sensitivity linearly across the full audio spectrum. It tilts it to the mids and highs. Where electric bass is concerned you want to compare sensitivity where it matters most, 50 to 80Hz. You can't do that with manufacturer data sheet charts, as they are measured with the driver mounted in a wall, and don't show the results in an enclosure. You need to use speaker modeling software to do that.

2 hours ago, Rubbersoul said:

Can I add a cab rated for less wattage, say 150W, without too great a risk of blowing it up?

Chances are you can't find one, not that it matters. Cab ratings are thermal, and next to meaningless. What matters is the mechanical displacement, how much air the driver cones can move without creating high distortion or suffering physical damage. You can find out the displacement if you know what drivers are being used and have their Thiele/Small specs, but cab manufacturers are loathe to reveal that. Barefaced does, with good reason. They boast as much displacement as anyone, more than most. It's the main reason why they're held in such high regard. https://barefacedaudio.com/pages/how-speakers-move-air-volume-displacement

K12H-200TC

3 hours ago, orangepeelneil said:

I've seen these speakers being advertised as guitar speakers as they have lots of headroom.

If the xmax spec is 2mm they have more headroom than most guitar drivers, the Greenback is 0.7mm, but the rest of the specs if similar to the K12H-200TC aren't well suited to guitar. I'd be very wary, as even the BN-12 300S has only 2.5mm xmax.

My concern about the K12T-200 is xmax. I can't find specs on it, but the K12H-200TC xmax is only 2mm. That's half what I'd consider the minimum acceptable. It results in a real world mechanical power limit of 25 watts. One can only speculate if the K12T-200 xmax is that short, but given the age of it and knowing Celestion came very late to the party where real bass specific drivers are concerned I wouldn't want to assume otherwise.

1 hour ago, Sparky Mark said:

Some also seem reluctant to stray from this noon position as if it is sacred and any adjustments equate to a compromise or corruption of a pure tone. 

IMHO those who have that attitude have no idea what a 'pure' tone is and would be shocked to see the measured response of their rig. No component has flat response, starting with the bass, ending with the room where it's being played. If tone controls weren't meant to be used they wouldn't be there.

Maybe it does, maybe it doesn't, but since the speaker doesn't have flat response it just doesn't matter. The amp probably has an EQ pre-shape as well, most do. Where EQ is concerned set it where it sounds best via trial and error. When it sounds good it is good.

The 2x8 ohm will be 6dB louder than  1x8 ohm. That's from the combination of 3dB additional sensitivity from the halving of impedance and 3dB additional sensitivity from the doubling of cone area. It will also have 6dB more maximum output, as the Vd (displacement) is doubled. That makes it 3dB louder at the same volume setting as the 1x4 ohm, and 6dB higher maximum output than the 1x4 ohm.

There's a saying in automobile circles that there's no replacement for displacement. It applies to speakers as well, because loudspeaker cones are pistons.

The 4 ohm will be 3dB louder, as the cone of the 4 ohm driver moves further with the same applied voltage. However, where maximum output is concerned they're the same, as both have the same maximum excursion. It just takes more voltage into the 8 ohm to get there, which takes only a slight increase of the volume knob, say from 5 to 6. Not from 5 to 10.