Blown Speaker in Barefaced Two10

[Bill Fitzmaurice]

1 hour ago, Woody1957 said:

Absolutely spot on! Running a high wattage amp on low volume is far better than running a much smaller wattage amp on full volume. 

What you need is an amp with head room and lots of it when playing bass otherwise the speakers will burn out, no matter how good or powerful they are.

That's the myth of underpowering. It's already been discussed in this thread with full explanation why it's not true. 😒

[kuras]

22 hours ago, Obrienp said:

I know you’ve taken it to a tech, so this might be completely irrelevant but I had a problem with my Two10 of similar vintage, which a previous owner had converted to an S. Distortion from one speaker, sounding like it had blown (to the uninitiated me). It turned out to be that a couple of the retaining bolts had worked themselves loose and the captive nuts’ thread had suffered as a result. Nuts replaced and everything tightened down really hard (Alex told me they use impact drivers at the factory, so I mean hard), and the problem was cured.
 

Apologies if this is so obvious you have already eliminated it. I had never come across it before.

Thanks for the advice. Unfortunately the broken speaker was distorting even when it was out of the cab, whereas the working one was fine. I managed to get a replacement speaker from Barefaced last week, so all is well now!

[Obrienp]

9 minutes ago, kuras said:

Thanks for the advice. Unfortunately the broken speaker was distorting even when it was out of the cab, whereas the working one was fine. I managed to get a replacement speaker from Barefaced last week, so all is well now!

Good to hear. Would you mind sharing how much a replacement driver costs? Just for future reference.

[kuras]

1 hour ago, Obrienp said:

Good to hear. Would you mind sharing how much a replacement driver costs? Just for future reference.

£150

[Obrienp]

Thanks. Better than I feared!

[Woody1957]

2 hours ago, Bill Fitzmaurice said:

That's the myth of underpowering. It's already been discussed in this thread with full explanation why it's not true. 😒

I'm sorry but my experience says otherwise....an underpowered amplifier driven hard can cause distortion and clipping....speakers don't like that.

Edited Saturday at 16:28 by Woody1957

[Bill Fitzmaurice]

🤫 Once again:

Clipped wave forms are harmful for tweeters, as they can increase the power in the high frequencies well above what what the tweeter normally receives. But no matter how hard the clipping the power will never exceed what the woofer normally receives in the lows. That's the science, and the science always works, whether you understand it or not.

 

As to blowing a 100w speaker with a 50w amp, for instance, yes, you can. Most 50w amps can deliver transients of 6dB above rated power, and that's means 200 watts. Is the amp clipping? Sure. Does the clipping cause damage? No. Over powering does.

 

BTW, a distortion pedal creates clipping, far more clipping than any amp is capable of creating. If clipped wave forms hurt woofers distortion pedals would not exist. Neither would synthesizers.

 

Edited Saturday at 17:02 by Bill Fitzmaurice

[Woody1957]

5 hours ago, Bill Fitzmaurice said:

🤫 Once again:

Clipped wave forms are harmful for tweeters, as they can increase the power in the high frequencies well above what what the tweeter normally receives. But no matter how hard the clipping the power will never exceed what the woofer normally receives in the lows. That's the science, and the science always works, whether you understand it or not.

 

As to blowing a 100w speaker with a 50w amp, for instance, yes, you can. Most 50w amps can deliver transients of 6dB above rated power, and that's means 200 watts. Is the amp clipping? Sure. Does the clipping cause damage? No. Over powering does.

 

BTW, a distortion pedal creates clipping, far more clipping than any amp is capable of creating. If clipped wave forms hurt woofers distortion pedals would not exist. Neither would synthesizers.

 

 

Edited Saturday at 22:09 by Woody1957

[asingardenof]

On 24/12/2024 at 00:47, Downunderwonder said:

The BF 10 is a solid 200w driver and BF rate the cab as fiine for  500w so long as it stays clean.

 

Fully distorted a 135w tube amp is 270w of howling misery so not going to bother a BF 210.

BF actually suggest you can run a Two10 with an 800W amp as long as it's clean.

[chris_b]

21 minutes ago, asingardenof said:

BF actually suggest you can run a Two10 with an 800W amp as long as it's clean.

 

My rigs are always over spec'd.

 

I used to run 2 Two10's with an 700 watt amp. As loud as you could want and bomb proof when playing a 5 string bass.

[Chienmortbb]

On 24/12/2024 at 00:47, Downunderwonder said:

The BF 10 is a solid 200w driver and BF rate the cab as fiine for  500w so long as it stays clean.

 

Fully distorted a 135w tube amp is 270w of howling misery so not going to bother a BF 210.

If an amp is rated at 135W RMS (average) the maximum output fully distorted (a square wave) will give 191 watts. There is a thought that tubes or Thermionic Valves have some magic attached to them but they do not. The laws of physics, or in this case, the power law variant of Ohm's Law always applies.

[Downunderwonder]

11 hours ago, asingardenof said:

BF actually suggest you can run a Two10 with an 800W amp as long as it's clean.

May as well use a 1000w amp, so long as it stays clean. If you start to overdo it the speakers will let you know by no longer staying clean.

[Downunderwonder]

11 hours ago, Chienmortbb said:

If an amp is rated at 135W RMS (average) the maximum output fully distorted (a square wave) will give 191 watts. There is a thought that tubes or Thermionic Valves have some magic attached to them but they do not. The laws of physics, or in this case, the power law variant of Ohm's Law always applies.

I am not aware of different maths for tubes. 

 

As power varies with the square of the voltage and the max of a sine is sqrt2 times the average RMS., square wave being peak to peak of the max ckean sine... you see where I get 2x RMS clean power in square wave.

 

 

[agedhorse]

On 24/12/2024 at 00:18, NAS Bass said:

Nothing to do with watts. I’ve seen and experienced low powered amps taking out speakers, usually the voice coil, because of a distorted signal. I suspect this may have been the case with the OPs 135w tube head. When I’ve seen it happen, it’s usually been caused by a tube head or distortion effect - nothing to do with power handling. I’ve know this happen with an Orange 120 and an Aguilar 412 - two speaker coils burned out. 

Sorry, this is not true. 

 

On 24/12/2024 at 01:47, Downunderwonder said:

Do tubes suffer DC offset? That's about the only way 135w can blow a BF woofer while still sounding clean.

 

I wonder if someone else had access to the cab? Either that or it's pure oddball failure of the stuff happens kind.

No, it's impossible to have DC offset on a tube amp, the output transformer prevents this.

 

On 11/01/2025 at 04:24, Woody1957 said:

Absolutely spot on! Running a high wattage amp on low volume is far better than running a much smaller wattage amp on full volume. 

What you need is an amp with head room and lots of it when playing bass otherwise the speakers will burn out, no matter how good or powerful they are.

Sorry, not at all true.

 

On 11/01/2025 at 08:22, Woody1957 said:

I'm sorry but my experience says otherwise....an underpowered amplifier driven hard can cause distortion and clipping....speakers don't like that.

Sorry, not true. Woofers don't care about distortion and clipping as long as the distorted/clipped power is within their RMS rating (and the rating is honest)

 

16 hours ago, asingardenof said:

BF actually suggest you can run a Two10 with an 800W amp as long as it's clean.

That's fine until the player has an accident (ie. cable pulled partially out of the bass causing a high power transient event) or the player has a lapse in good judgement that typically goes hand in hand with unrealistic expectations.

[NAS Bass]

3 hours ago, agedhorse said:

Nothing to do with watts. I’ve seen and experienced low powered amps taking out speakers, usually the voice coil, because of a distorted signal. I suspect this may have been the case with the OPs 135w tube head. When I’ve seen it happen, it’s usually been caused by a tube head or distortion effect - nothing to do with power handling. I’ve know this happen with an Orange 120 and an Aguilar 412 - two speaker coils burned out. 
 

 

Sorry, this is not true. 

Edited yesterday at 07:52 by NAS Bass

[NAS Bass]

I know, I imagined it

[Obrienp]

I have to declare myself thoroughly confused by the conflicting arguments here. If in doubt (and after reading this thread I have plenty of it) I stick to an old adage that was imparted to me when I bought my first decent gear as a teenager (early 1970s): to avoid blow outs, unwanted distortion, etc, the speaker cab(s) needs to have an RMS rating twice that of the amp. Now this may have been a shifty salesman getting a callow youth to spend more than was necessary but there may be a grain of truth in it?

 

I am sure that speaker technology has moved on leaps and bounds since my youth but I still wouldn’t feel safe running an amp that had a higher rating than the cab, even though I would never have the master anywhere near max. I feel nervous enough running my BF Two10 with amps that have the same RMS rating. The LFSys Monza gives me a comfortable feeling because, at 600 watts AES, it has twice the rating of any of my amps @ 8 ohms.

 

Tell me why I am wrong.

[DGBass]

Having a cab rated at twice the rating of the amp was certainly something that was widely suggested a good plan to have when I started playing many years ago. It may seem over cautious to some, but I've never blown a driver in a cab ever using this approach. I once asked a local repair guy in our local music shop why I needed a 200 watt cab for my 100 watt superbass, and why all the local shredders with their 100 watt super leads seemed to managed ok with their 100w greenback loaded 4x12s. The truth he said was that the shredders had their cabs back in for repair to blown drivers every three or four months. Over time the 25W Greenback drivers were all replaced with 50W McKenzie drivers and after that was done, the cabs never came back for repair again. The point being he said, having a bit of reserve in the tank thermally speaking is no bad thing where speakers are concerned. I've run a 500watt class A/B head into a 200watt 4 ohm cab in recent times as an experiment, and it worked fine for a lo-fi gig but I wouldn't do that on a regular basis. Listening carefully to a cab will often tell you whether the drivers are struggling long before they are ready to fail. Speaker ratings these days do seem to be getting more consistent and perhaps accurate with quality component manufacturers providing lots of technical data openly for their products. I wish i could say the same about power ratings for modern amps. The same amp could be rated 800watts @ 10% THD, 703watts @ 1%THD and 596 watts @ 0.01 THD. They may all be accurate figures for the same amp, but which of those ratings will sell the most units?  I'm always a bit wary of claims where its said as long as you use a clean signal, you can use oodles and oodles and oodles of power without affecting your speaker even if its rated the same or below an amplifier rating you don't really know is real world accurate.  Hmmm. Yes its all very confusing to me. As far as the OP is concerned, I'd love to know if BF asked to return the faulty driver for an investigation into why it failed in the first place. 

[chris_b]

Wrong thread!!!!

Edited yesterday at 12:54 by chris_b

[Bill Fitzmaurice]

2 hours ago, Obrienp said:

I am sure that speaker technology has moved on leaps and bounds since my youth but I still wouldn’t feel safe running an amp that had a higher rating than the cab, even though I would never have the master anywhere near max. I feel nervous enough running my BF Two10 with amps that have the same RMS rating. The LFSys Monza gives me a comfortable feeling because, at 600 watts AES, it has twice the rating of any of my amps @ 8 ohms.

 

Tell me why I am wrong.

You're not wrong. It's perfectly safe to use an amp rated at even ten times the speaker rating so long as you employ the volume control. It's perfectly safe to use an amp rated at one tenth the speaker rating as well, even if you crank it into hard clipping, so long as you don't have a tweeter. The myth of underpowering came about decades ago after JBL published a document on how amplifier clipping could damage 'the high frequency components of their loudspeaker systems high frequency devices'. It probably took three re-tellings of the tale, if not less, before 'clipping can damage high frequency components' morphed into 'clipping kills speakers'. Engineers like myself have been countering that notion ever since, but it's like a never ending game of whack a mole. The truth of the matter is succinctly summed up in this quote:

 

There's no such thing as "underpowering" a loudspeaker. The loudspeakers really don't care about the shape of the waveform. A square wave is not by itself a killer of tweeters, woofers, etc. Well over 90% of the power put into a loudspeaker driver turns into heat, whether the waveform is square or not. Overpowering (thermal damage from too much power) and over-excursion (excessive cone travel, typically from low frequency energy) are what damage loudspeakers.

 

Bob Lee
Applications Engineer, Tech Services Group QSC Audio
Secretary, Audio Engineering Society

 

Rebuttal is welcome from anyone claiming to have Bob Lee's level of expertise.

 

[Beedster]

9 minutes ago, Bill Fitzmaurice said:

Rebuttal is welcome from anyone claiming to have Bob Lee's level of expertise.

 

Destined to become one of the all-time great BC quotes 👍

[stevie]

3 hours ago, Obrienp said:

I have to declare myself thoroughly confused by the conflicting arguments here. If in doubt (and after reading this thread I have plenty of it) I stick to an old adage that was imparted to me when I bought my first decent gear as a teenager (early 1970s): to avoid blow outs, unwanted distortion, etc, the speaker cab(s) needs to have an RMS rating twice that of the amp. Now this may have been a shifty salesman getting a callow youth to spend more than was necessary but there may be a grain of truth in it?

 

I am sure that speaker technology has moved on leaps and bounds since my youth but I still wouldn’t feel safe running an amp that had a higher rating than the cab, even though I would never have the master anywhere near max. I feel nervous enough running my BF Two10 with amps that have the same RMS rating. The LFSys Monza gives me a comfortable feeling because, at 600 watts AES, it has twice the rating of any of my amps @ 8 ohms.

 

Tell me why I am wrong.

 

I think this is a good practical rule of thumb for bass players. Speaker power handling can be a complicated subject but there are good reasons for not driving your loudspeakers to their max.

[agedhorse]

Driver construction has improved greatly over time, especially the bobbin materials and adhesives used. Also, for bass speakers, more attention has been placed on improving mechanical limits. This means that in general, matching the rms rated power of the amp to the rms rated input of the speaker is generally pretty safe. The main exception to this rule is when using heavy distortion and/or heavy compression. Under these conditions, I recommend some derating of speakers (maybe to 75% of their published rating) but conservatively rated speakers may not need this.

 

There were two parts to JBL’s recommendations, unfortunately they get mixed up in the discussions… the part Bill quoted was for the HiFi industry and addressed the high frequency distortion impacts on tweeters mostly.
 

There was also a section for OEM (original equipment manufacturer) customers regarding low frequency drivers for MI (musical instrument) applications which recommended a 50% derating for use with distorted and compressed program material. This was also incorporated into the OEM warranty agreements. 
 

I completed the JBL reconing and service school back in 1978 and worked at a service center that was JBL certified very early in my career. 

[kuras]

2 hours ago, DGBass said:

As far as the OP is concerned, I'd love to know if BF asked to return the faulty driver for an investigation into why it failed in the first place. 

Nope. While I was grateful for quick delivery once I managed to get hold of them via the phone, it’s shame to find they weren’t more interested in the problem with their speaker 

[Dan Dare]

It seems we're starting to strain at this. Those with years of expertise and experience, such as Bill, Aged Horse and Stevie, have given good advice above, which should be all we need.

 

To summarise, don't abuse your gear, ensure it matches (within reason - a 1000w amp with a 100w cab is almost bound to end in tears, but smaller discrepancies are fine as long as you are sensible) and that you use it within its specified limits.

 

Accept that drive units, as mechanical devices, are going to wear out/fail on occasion. Even electronics components don't last for ever. C'est la vie.