Watt is normal and What is not?

[jazzyvee]

Firstly i must emphasise that this is not a complaint about Barefaced cabs it's me trying to understand how i should expect a speaker to behave under differing conditions. I have only previously owned mesa boogie ph cabs so no real diverse experience of much else.

So just trying to understand if what i am hearing is normal, am i giving the cab too much bottom end at any wattage or anything else.
I do have an issue with what i am hearing through one of my 1x12 cabs and BF been quick in sending me a new speaker, but before i start to test it on my rig i just want to know what is normal and what is not. 

 

if i have any bass cab rated at 800w or 600w at 8ohms and a bass amp that will deliver below that wattage into an 8 ohm cab:

• what are the circumstances that would make the speaker fart out?
• When is it right for me to expect the speaker to farting out do because i am asking too much. 
• what circumstances is it wrong for the speaker to fart out and what does that sound like. 
• how do i test my tweeter to find out if that is ok.

 

My intended use of the BBII has always been for smaller gigs using 5 and 4 string basses Eub covering predominantly jazz based music and reggae. All was fine until i paused gigging during lockdown and the cab was not used, then when i started using the cab again last year the issue became evident. 

 

Again can i stress this is not a barefaced bashing thread as i have three more of their cabs which all work perfectly and i am completely happy with. So i am surprised that this situation. 

.

I plan to call BF on monday also for advice.

 

Edited March 6, 2022 by jazzyvee

[Bill Fitzmaurice]

Farting out occurs when the combination of power and frequency attempts to force the cone to travel beyond its mechanical limits. The cure is to reduce the volume and/or low frequency EQ. The cab power rating doesn't indicate whether an amp can push the cone too far because that rating is thermal, not mechanical. Cone excursion goes up as frequency goes down, so a 500 watt signal may not cause over-excursion at 500Hz while a 50 watt signal at 50Hz may. The simple answer to farting out is that if one cab won't handle the combination of volume and bass EQ that you use you need two or more cabs, or one cab with more driver displacement.  https://barefacedaudio.com/pages/how-speakers-move-air-volume-displacement

[DaleASmith]

surely there's a bigger risk of distortion from a smaller amp. Just as in HiFi. 

 

If your cab can handle 800watts and you run a 300 watt amp into it at full tilt, there's a risk of the power amp distorting, producing non sine waves and wrecking your speakers. Maybe that's what your hearing.

 

Your safest bet is to use an amp that is too big for the job, not too small. 

[Bill Fitzmaurice]

That's the Myth of Underpowering, and it's just that, a myth. If amp clipping, or clipping anywhere in the signal chain, hurt woofers guitar players would be swapping them out at every break. Clipping is only potentially dangerous to tweeters, because the high frequency content is abnormally high. And we don't play sine waves.

[Dad3353]

2 hours ago, DaleASmith said:

...producing non sine waves and wrecking your speakers...

 

So there we have it, official. 'Fuzz' pedals will destroy your speakers, word. 

 

...

 

 

[DaleASmith]

24 minutes ago, Dad3353 said:

 

So there we have it, official. 'Fuzz' pedals will destroy your speakers, word. 

 

...

 

 

 

😂

That's not what I meant, but I guess you already know that...🙂

 

If I've misunderstood I'm happy to be enlightened.. 

Edited March 6, 2022 by DaleASmith

[Downunderwonder]

50 minutes ago, DaleASmith said:

 

😂

That's not what I meant, but I guess you already know that...🙂

 

If I've misunderstood I'm happy to be enlightened.. 

Read the other post twice more. Square waves are not square.

 

Regarding the OP, many times I have heard of stray material getting in through the port and lodging behind the cone. Everything from a Homer Simpson toy to a lolly wrapper.

 

The other gotcha is a dying battery in your bass preamp or a pedal.

 

You would have to really slam a BB2 for it to break the woofer. Rig up some music through it at low volume and increase. If it gets deafening without the distortion you'll need some very good hearing protection. Putting your ear down to the speakers you should be able to hear if it's coming from the horn or the 12.

[Bill Fitzmaurice]

1 hour ago, DaleASmith said:

 

😂

That's not what I meant, but I guess you already know that...🙂

It's not what you meant, but clipping is clipping, no matter where it occurs in the signal chain. It can be bad for tweeters, that's why guitar cabs don't use them, but will never hurt a woofer.  http://www.bcae1.com/2ltlpwr.htm

[jazzyvee]

8 hours ago, DaleASmith said:

surely there's a bigger risk of distortion from a smaller amp. Just as in HiFi. 

 

If your cab can handle 800watts and you run a 300 watt amp into it at full tilt, there's a risk of the power amp distorting, producing non sine waves and wrecking your speakers. Maybe that's what your hearing.

 

Your safest bet is to use an amp that is too big for the job, not too small. 

hmm, well my two main amps that I use for most gig are a Synq 1K0,  https://synq-audio.com/digit-1k0  and my Crown XLS1502  both run at 300w into 8 ohms should I try them in bridge mode with this cab, not at full volume but to see if I get a better performance of them with less risk of distorting?  
 

 

[jazzyvee]

7 hours ago, Bill Fitzmaurice said:

That's the Myth of Underpowering, and it's just that, a myth. If amp clipping, or clipping anywhere in the signal chain, hurt woofers guitar players would be swapping them out at every break. Clipping is only potentially dangerous to tweeters, because the high frequency content is abnormally high. And we don't play sine waves.

Interesting, as the most of the cracking sound appears when the tweeter is on and less so when it's off.

[jazzyvee]

5 hours ago, Downunderwonder said:

Read the other post twice more. Square waves are not square.

 

Regarding the OP, many times I have heard of stray material getting in through the port and lodging behind the cone. Everything from a Homer Simpson toy to a lolly wrapper.

 

The other gotcha is a dying battery in your bass preamp or a pedal.

 

You would have to really slam a BB2 for it to break the woofer. Rig up some music through it at low volume and increase. If it gets deafening without the distortion you'll need some very good hearing protection. Putting your ear down to the speakers you should be able to hear if it's coming from the horn or the 12.

Unlikely to have any of those objects in the cab and I did take the speaker out to have a look inside and there was nothing in there that shouldn't be there.

My bass has an external 36vdc power supply so no issue with loss of power to the bass and I have the internal trip pots set at the lower end of the range as I know they are really hot on full power.
I have a couple of mates with a rehearsal studio so I will try your suggestion of loud music there to avoid annoying my neighbours.

 

[Downunderwonder]

1 hour ago, jazzyvee said:

hmm, well my two main amps that I use for most gig are a Synq 1K0,  https://synq-audio.com/digit-1k0  and my Crown XLS1502  both run at 300w into 8 ohms should I try them in bridge mode with this cab, not at full volume but to see if I get a better performance of them with less risk of distorting?  
 

 

That's a really easy way to blow the cab to bits.

[jazzyvee]

That is exactly why i don't use bridge mode. But i felt the need to ask just to rule that option out.👍

Edited March 7, 2022 by jazzyvee

[JapanAxe]

At a sound check I was getting a nasty crackling and thought there might be a problem with the drivers in my BF cab. Turned out to be a bad connection in my tuner pedal.

[stevie]

My rule of thumb is to match the amp output with the AES power rating of the speaker. That usually gives a good match in my experience and should be relatively safe as long as you're careful. Many of the popular 500W amps produce about 300W at 8 ohms, which makes a 300W speaker a good match. The driver manufacturers test their products to AES standard and publish the results, but some bass cab manufacturers use their own figures, which can be much higher. Look for an AES rating, sometimes stated as rms. Anything else is likely to be 'music power', or twice the AES rating.

 

Having said that, there's a lot more to it than power ratings. Ideally, you want your amplification to be cruising. So if in doubt, use speakers with a much higher power handling spec than the amp you're using - if you can.

 

 

[Downunderwonder]

17 hours ago, jazzyvee said:

Interesting, as the most of the cracking sound appears when the tweeter is on and less so when it's off.

I think on the BB2 the 'tweeter' is a proper horn and the knob is a control on a crossover that sweeps the mid point, so not an attenuator as such.

 

That being the case it might explain why ''off'' clears it up some and why BF sent you a new woofer without a full diagnostic check. I still reckon they jumped the gun on that.

[stevie]

This one keeps coming up. I think you'll find, @Downunderwonder that the attenuator is just that - an L-pad attenuator as found in most bass cabs with a tweeter. A lot of people seem to believe it's more complicated than it is. An L-pad by definition changes the crossover point, which is why nobody but bass cab manufacturers - and 1960s Japanese hi-fi speaker manufacturers - use them.

[Phil Starr]

On 06/03/2022 at 10:43, jazzyvee said:

 

So just trying to understand if what i am hearing is normal, am i giving the cab too much bottom end at any wattage or anything else.
I do have an issue with what i am hearing through one of my 1x12 cabs and BF been quick in sending me a new speaker, but before i start to test it on my rig i just want to know what is normal and what is not. 

 

if i have any bass cab rated at 800w or 600w at 8ohms and a bass amp that will deliver below that wattage into an 8 ohm cab:

• what are the circumstances that would make the speaker fart out?
• When is it right for me to expect the speaker to farting out do because i am asking too much. 
• what circumstances is it wrong for the speaker to fart out and what does that sound like. 
• how do i test my tweeter to find out if that is ok.

 

 

 

I think you've answered your own question. If one cab is making a noise and the other identical cab isn't then it's the cab. That wasn't what you were asking though.

 

• Farting out is usually the description for a bass driver reaching it's mechanical limits, often the rear of the coil banging on the back of the magnet but it can be other things. If the speaker reaches this stage it's also likely to be over-heating and producing high levels of distortion.
• Asking too much is about too much power or excessive bass content. @stevie has posted whilst I've been typing and I was going to say pretty much the same. The one qualification is about eq, even relatively light bass boost can more than double what you are asking of your amp and speaker and an HPF halve the demands so a lot depends upon the sound you are going for.
• It's always wrong to drive your speaker to audible distortion levels
• disconnect it and see if the distortion goes

 

 

[jazzyvee]

Cut a long story out with a combination of new bits from Barefaced, chopping and changing various combinations of amps, preamps and speaker parts to try to work out where the issue is. I have traced it to the Synq 1K0 power amp. I contacted the company and the only thing the suggested was to check the input capacitors, so i presume they are aware of that issue. It's now at a repair centre and the BBII is back with it's original innards and working fine with my other setups.

Thanks for your input and Phil Starr, your first sentence is clearly correct. But I had to go through everything I could to see if it was a combination of other things in the chain or just the cab. 

Thanks everyone for chipping in to assist.