Bill Fitzmaurice

12 hours ago, Phil Starr said:

I've never owned on of those Peavey's but I've played through a friends. I thought it was pretty wonderful and looked out for a used one for a while. I'm really keen on a graphic particularly when playing in an acoustically difficult space.

+1, twelve total bands of EQ beats three bands of EQ every time. One just has to know how to use it. The ELF EQ centers are at 80 Hz, 400 Hz and 4.2 kHz, so approximating the same tone with the Peavey wouldn't be all that difficult.

Vintage Peaveys had the pre on the front panel, the power amp on the rear panel. You'd have to open yours up to see if that's the case with it.

You would want it off, or way down, with distortion effects.

It's a guitar combo, from the 1990s.

2.5mm is probably overkill, 1.5mm should do, but there's no reason why you can't use 2.5mm. 2.5mm is required for runs of 3 meters or more or with very high power.

Apples and oranges, mainly due to the different tone stacks. The Bassman bass knob set at 10 was about the same as the Ampeg set at 6. But you really couldn't run the Ampeg higher than 6 anyway, as it would cause the speaker to fart out.

1 hour ago, SimonK said:

if you haven't tried two amps simultaneously - I would!

The first time I did that it was with my '65 Fender Bassman and Tom Hamilton's '66 Ampeg B-15. That would have been in '67 or '68.

1 hour ago, SimonK said:

I'd rather run two amps as that makes a much bigger difference to the sound than a third cab.

Only if one amp lacks the current capacity required to drive three cabs. Speaker output is determined by excursion, excursion is determined by voltage swing, an amp will deliver the same voltage swing into three cabs as it will with one or two. When trouble occurs it's because the amp lacks the ability to deliver the same current into three cabs as it does into one or two. If amps had unlimited current capacity we could use as many cabs as we could haul, with no concerns about impedance.

FWIW most of the improvement is the result of the third cab being closer to ear level, allowing the mids and highs to be more easily heard. You can come close to the same result with a stand. So long as it's less than 70cm high there's no loss of bass coupling with the floor.

1 minute ago, Bassy said:

Just need to point out that Eden recommend that you do not turn off the tweeter as it will blow the fuse in the crossover.

 

That indicates it's a defective design. A properly configured LPad will maintain a constant impedance load on the crossover, which is a necessity not only to protect the crossover components but also to maintain the crossover transfer function.

I don't think cabs are any more genre specific than basses.

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But the cabs do not like any drive/fuzz pedals, as the tweeters become very harsh with distortion.

That's why guitar cabs don't have tweeters, and why most bass cabs with tweeters have the ability to turn them off.

1 hour ago, Owen said:

There is a hi z / low z option on it which did not seem to make a huge amount of difference. But it sounded MIGHTY fine.

The high Z is 4k. A bass amp input impedance is typically 1 meg.

Impedance probably explains it. The Neve is designed to operate with low impedance sources. A passive bass is a high impedance source.

That indicates the hiss is sourced in the power amp section, so it's probably not the mains. It's an inexpensive amp so it may be normal for it.

Beware of the pitfalls of doing this indoors. Some years ago there was a much ballyhooed subwoofer shootout in the States. A dozen or so subs were compared, and the RTA measured results were all quite similar. That's because what they were measuring wasn't so much the individual subwoofers response as it was the room response. If the room has recording studio acoustics you're good, but if it has gymnasium acoustics it may be a futile exercise.

As best I can tell the cab internal volume is about 60 liters, so a 75 mm ID tube 35 mm long would give roughly 50Hz tuning. But the port velocity is off the charts. You need two, 120 mm long. 

The video points out that at the tuned frequency cone movement is at a minimum, while port output is at its maximum. However, one cannot assume that 41 Hz gives the best result. That you determine with modeling software. With most bass cabs the best result is around 50-55 Hz. He also gave the manufacturer too much credit on the port sizing. They're much too small. His methodology is off as well. To find the exact tuned frequency you use a sine wave generator, slowly sweeping the frequency until the cone movement is at its minimum.

2 hours ago, Bassman Rich said:

 I don't really want to hack the cab about, so can't really increase the port diameter from 7.5cm. I don't suppose you could advise on port length for that diameter could you??

That diameter is far too small, so you'd end up with port air mass velocity that's too high, resulting in port noise. For two tens in an average size cab with 50Hz tuning the minimum required port diameter is 12 cm, or a pair of 8.5 cm. 

If you remove the tweeter and don't replace it with a port of the correct length and area you'll likely make things worse. Getting it right requires modeling, not just to find the correct tuning frequency but also acceptable port air mass velocity. This assumes the driver will work well in a ported cab at all. Many drivers are compatible with both sealed and ported alignments, but those which are ideally suited for the one are not suitable for the other. 

If it's loaded with four 16 ohm speakers they may be wired to 4 ohms already.

You can use a bass cab for guitar but you won't get any crunch or compression, let alone anything close to woman tone out of it. The only way you'll get anything other than totally clean is with effects...unless you manage to score a '59 Bassman. 

The additional output is roughly 3dB, which isn't massive. If the 210 isn't enough you're better off with another 210. The main advantage to adding a 110 would be the higher position of the 110, making it easier to hear the mids and highs, but you can accomplish that with a tilt back amp stand.

Wrong forum. This is the PA section.

On 21/08/2024 at 07:18, TimR said:

So any higher frequencies coming from the ports. Will be constructive/destructive to what's coming out of the speakers. 

However, in practical very unlikely to hear any difference unless the ports are at ear level.

Higher frequencies seldom come from ports at a significant level. About the only time that happens is when a rear mounted port is in back of a woofer, which would be rare, as a port would have to be very short to fit there. When there isn't a direct line of sight through the port to the cone higher frequencies won't come through the ports at high levels. For that matter low frequencies don't actually come through the ports. This goes to how ports work. The air mass within the port vibrates back and forth, the portion of that slug of air that meets the outside air acts like another speaker cone. Unlike a speaker cone it only vibrates at and near the tuned frequency, so the bandwidth of the frequencies it passes at a high level is quite small, on average no more than an octave.

In this case it won't matter by much. Since the woofers only operate up to 800Hz that places their center to center distance within the required 1 wavelength, which is 42cm at 800Hz. There is some loss of horizontal dispersion below 800Hz where the woofers operate, but not enough to be concerned about.