Bass Amps, Speaker cables, ohms, etc...

[Lt. Bob]

tweeters are only useful if you're gonna be doing a bunch 'o' slap/pop bass stuff.
For standard rock or country or jazz bass lines they're not very important.

Crossovers won't really give you any extra tonal possibilities ..... they're mainly to pull a bit of lows out of the tens if they start to overload. Most modern bass 10's can handle everything making a crossover not too important

 

[Whale Bone]

Now I get it! You can try it with the PA cabinets, but if there is a tweeter in the cabinet, don't turn it up too loud or you will blow it.

Why are you worried about this? Surely the PA speaker has a crossover for the tweeter like a bass cabinet would. A tweeter doesn't want the full audio range in a PA, keyboard or bass cabinet. If you run the bass through the PA, and crank it into the PA speakers, the tweeter won't blow up. If the PA cabinet is rated at high enough wattage for the amp, then it should be fine, shouldn't it?

 

[Farview]

Why are you worried about this? Surely the PA speaker has a crossover for the tweeter like a bass cabinet would. A tweeter doesn't want the full audio range in a PA, keyboard or bass cabinet. If you run the bass through the PA, and crank it into the PA speakers, the tweeter won't blow up. If the PA cabinet is rated at high enough wattage for the amp, then it should be fine, shouldn't it?

Bass amps can pump out more high end than you would ever send to a PA tweeter. Think about it: If there is enough 3k in the signal for you to be able to hear it through a 15 inch speaker, it's going to roast a tweeter. The tweeters and crossovers in bass cabinets are designed to handle it. The tweeters and crossovers in PA cabinets are designed for a different purpose. (It's also a different type or tweeter)

 

[ggunn]

Bass amps can pump out more high end than you would ever send to a PA tweeter. Think about it: If there is enough 3k in the signal for you to be able to hear it through a 15 inch speaker, it's going to roast a tweeter. The tweeters and crossovers in bass cabinets are designed to handle it. The tweeters and crossovers in PA cabinets are designed for a different purpose. (It's also a different type or tweeter)

Color me skeptical. Bass guitar is often routed through the PA at very high volume with no ill effects, and most of the spectral content of bass is in the low end. I'd be more worried about the low freq drivers than the horns.

 

[Whale Bone]

Most bass amps I've heard favor low-end not high-end. Of course there are amp/speaker combinations that put out brittle highs. But can the highs a bass amp puts out really be drastically more than the highs a PA puts out with keys, vocals and guitars? I would expect to see that on average PA amps produce flatter output than bass amps, which I would expect to lack in the upper end on average. And if the cabinets are rated for the comparable wattages with crossovers designed accordingly, I don't see the problem.

As for the 15" cutting argument, I would attribute cutting through to attention to mid range from the bass or the amp, e.g. not scooping out the mids, and proper cabinet design. 15" speakers can certainly produce mid-range tones.

If you take a bass head and run it through a cabinet with a tweeter, you'll likely get more mid/high-end than on the same head through a cabinet without (given the same woofer). That's likely because of the cabinet, not the amp.

As usual, I'm prepared to be wrong if convinced...

 

[Farview]

Color me skeptical. Bass guitar is often routed through the PA at very high volume with no ill effects, and most of the spectral content of bass is in the low end. I'd be more worried about the low freq drivers than the horns.

It's different. For the same reason that micing a distorted guitar amp and putting it through the PA system won't blow the tweeters when distorting the PA amp will.

Bass cabinets use bullet tweeters, PA cabs do not.

If you have a PA cab lying around, plug your bass amp into it and play a show - test the tweeter - replace the tweeter. I've seen three people in the last 25 years do this, it all resulted in me replacing the diaphragm.

 

[Farview]

Most bass amps I've heard favor low-end not high-end. Of course there are amp/speaker combinations that put out brittle highs. But can the highs a bass amp puts out really be drastically more than the highs a PA puts out with keys, vocals and guitars?

Start slapping and popping on the bass and you will get much bigger transients than would normally be sent through the PA.

Most bass RIGS favor low end. The amps really don't. The amps are voiced to sound right through the speakers that the designers assumed you would be using. Since 10s and 15s really don't have a response that favors the high end, the amps are voiced with enough high end to make up for the speaker response.

Same thing with guitar amps. Unplug your Marshall from the 4x12 cabinet and plug it into a PA cabinet. (not for very long) Listen and marvel at the amount of high end you can hear now that you are listening through a speaker that will efficiently reproduce it.

I would expect to see that on average PA amps produce flatter output than bass amps, which I would expect to lack in the upper end on average. And if the cabinets are rated for the comparable wattages with crossovers designed accordingly, I don't see the problem.

Both the power amp of a PA and the power section of a bass amp will be pretty flat. The difference is the signal you feed them.

If you take a bass head and run it through a cabinet with a tweeter, you'll likely get more mid/high-end than on the same head through a cabinet without (given the same woofer). That's likely because of the cabinet, not the amp.

Correct

 

[Lt. Bob]

It's different. For the same reason that micing a distorted guitar amp and putting it through the PA system won't blow the tweeters when distorting the PA amp will.

Bass cabinets use bullet tweeters, PA cabs do not.

If you have a PA cab lying around, plug your bass amp into it and play a show - test the tweeter - replace the tweeter. I've seen three people in the last 25 years do this, it all resulted in me replacing the diaphragm.

Ditto, I had a gig a couple of years ago and the easiest thing for me to do at that particular gig was to use a PA cab ...... and a pretty decent one which I had used in a PA with everything mik'd at fairly high volumes for years. Took two gigs to eat the horn driver.

 

[ggunn]

Well, I guess I stand corrected; I bow to the Voices Of Experience.

 

[Lt. Bob]

Well, I guess I stand corrected; I bow to the Voices Of Experience.

Hey ..... it surprised the hell outta me and I know this stuff pretty well.
I thought just like you did ..... what's the difference?
But a new diaphragm for the horn bought me a lesson!

 

[Whale Bone]

Farview, aren't you still just talking about driving a speaker cabinet with an amp that's too powerful? Tweeters are often low-power, not expecting to see much (after a crossover), so if you overpower a cabinet, the tweeter could easily be the first thing to suffer. A 100w bass head isn't going to fry the tweeter in a 600w PA cabinet, right? Perhaps it is simply that most bass heads are going to be more powerful than your average low/mid-end PA cabinet, and that's why you stand an easy chance of blowing up your tweeter.

 

[Farview]

Farview, aren't you still just talking about driving a speaker cabinet with an amp that's too powerful? Tweeters are often low-power, not expecting to see much (after a crossover), so if you overpower a cabinet, the tweeter could easily be the first thing to suffer. A 100w bass head isn't going to fry the tweeter in a 600w PA cabinet, right?

A 100 watt bass amp is much more likely to blow a tweeter than a 600 watt amp because you are more likely to overdrive the amp. A clipped 100 watt amp will be putting out way more than 100 watts. When the amp clips, it generates a ton of upper harmonics. Those harmonics are sent directly to the tweeter.


Think about how bright the signal from a bass amp has to be to not sound dull and lifeless through a single 15 inch speaker. Think about how much 3k has to be coming out of the amp for you to hear it coming out of a speaker thats frequency response is stated as 35hz - 1khz. Now think about plugging that amp into a cabinet that is really efficient at that frequency.

Also take into consideration that the crossover frequency on a bass cabinet is around 6k and the crossover frequency of a PA cabinet is normally around 1.5k. There is a lot more power at 1.5k than at 6k...

 

[Whale Bone]

I think you misunderstood me. I said:
'A 100w bass head isn't going to fry the tweeter in a 600w PA cabinet, right?'

Meaning a cabinet rated for 600 watts. My point is about driving cabinets with more power than they're rated vs. driving cabinets that are rated at enough power to handle the amp.

 

[Farview]

I think you misunderstood me. I said:
'A 100w bass head isn't going to fry the tweeter in a 600w PA cabinet, right?'

Meaning a cabinet rated for 600 watts. My point is about driving cabinets with more power than they're rated vs. driving cabinets that are rated at enough power to handle the amp.

I understood what you said. The truth is that it is easier to blow tweeters by under-powering a cabinet than over-powering it. This is because when you clip an amp (which you are much more likely to do when you don't have a lot of power) it creates a square wave which has a ton of upper harmonics at high power.

 

[ggunn]

A 100 watt bass amp is much more likely to blow a tweeter than a 600 watt amp because you are more likely to overdrive the amp. A clipped 100 watt amp will be putting out way more than 100 watts. When the amp clips, it generates a ton of upper harmonics. Those harmonics are sent directly to the tweeter.

Now, that I've done with a clipping PA system, although it was the crossovers I took out rather than the hi freq drivers.