I have a pair of 15 year old B&W DM600s. The woofer on one of them isn't working.
The problem arose when I plugged a digital guitar amp modeller through my hifi amplifier. I know this is a stupid thing to do, but I had the amp really quiet and I was well away from the speakers so didn't expect major problems. Anyway, after playing guitar through this setup for about a week I noticed that the woofer wasn't working on one of the speakers. The tweeter was fine, and the other speaker was fine as well. I tried swapping the speakers around and the problem persisted, so it's definitely the speaker and not the amplifier.
I don't know much about speakers. Is there a way to fix this? DM600s got for well under £100 on eBay, so it would have to be an inexpensive DIY repair.
The problem arose when I plugged a digital guitar amp modeller through my hifi amplifier. I know this is a stupid thing to do, but I had the amp really quiet and I was well away from the speakers so didn't expect major problems. Anyway, after playing guitar through this setup for about a week I noticed that the woofer wasn't working on one of the speakers. The tweeter was fine, and the other speaker was fine as well. I tried swapping the speakers around and the problem persisted, so it's definitely the speaker and not the amplifier.
I don't know much about speakers. Is there a way to fix this? DM600s got for well under £100 on eBay, so it would have to be an inexpensive DIY repair.
The drive unit is the woofer ... so I basically need to replace both woofers? Sorry if these questions seems obvious, I'm new to this.
How much is it likely to cost me, and where would I get the parts from? Do I need to contact B&W, or one of their dealers, and what should I ask for? Is the repair worthwhile in your opinion?
I had a Fender Stratocaster plugged into the speakers, via a Line6 Pod modeller and a Marantz hifi amp. What exactly might have happened to cause a speaker to fail?
How much is it likely to cost me, and where would I get the parts from? Do I need to contact B&W, or one of their dealers, and what should I ask for? Is the repair worthwhile in your opinion?
I had a Fender Stratocaster plugged into the speakers, via a Line6 Pod modeller and a Marantz hifi amp. What exactly might have happened to cause a speaker to fail?
Hi,
Your choice will probably be one new (expensive) B&W driver
or shoehorning two replacement drivers into the cabinets.
There is an electronics shop in Brighton that sometimes has
B&W drivers in (B&W are based in Worthing near Brighton).
I could check them if your driver is gone.
The other alternative is probably two of these :
http://www.wle-shop.co.uk/modules/shop/view.asp?catid=79&Prodcode=902.423
Though getting them to fit may be a problem, or not.
And of course they are not likely to sound correct but
they will be working in a fashion.
also see :
http://www.skytronic.co.uk/product/product.php?s=902.195
Local supplier :
http://www.skytronic.co.uk/about/storefinder.php
/sreten.
Your choice will probably be one new (expensive) B&W driver
or shoehorning two replacement drivers into the cabinets.
There is an electronics shop in Brighton that sometimes has
B&W drivers in (B&W are based in Worthing near Brighton).
I could check them if your driver is gone.
The other alternative is probably two of these :
http://www.wle-shop.co.uk/modules/shop/view.asp?catid=79&Prodcode=902.423
Though getting them to fit may be a problem, or not.
And of course they are not likely to sound correct but
they will be working in a fashion.
also see :
http://www.skytronic.co.uk/product/product.php?s=902.195
Local supplier :
http://www.skytronic.co.uk/about/storefinder.php
/sreten.
No possibility of rebuilding the blown driver? Around here there are a number of options (shops actually) for recone/VC replacement - this is probably dependent in this case on being able to get OEM parts from the manufacturer. I'm not sure how economical this would be compared to a new driver from BW which I would guess is your best bet for performance reasons.
Incidentally if you destroyed one woofer and were driving both channels it is very likely that the other woofer has sustained damage as well - it just hasn't completely failed yet. (I bet the VC wire's insulation is pretty cooked though.)
Depending on what you were doing you may have greatly exceeded the dissipation limits of your woofer voice coils if there was substantial energy in the bass waveform below the effective rolloff frequency of those woofers. You probably would not have even realized it at the time. Hifi speakers generally don't make good MI speakers..
Incidentally if you destroyed one woofer and were driving both channels it is very likely that the other woofer has sustained damage as well - it just hasn't completely failed yet. (I bet the VC wire's insulation is pretty cooked though.)
Depending on what you were doing you may have greatly exceeded the dissipation limits of your woofer voice coils if there was substantial energy in the bass waveform below the effective rolloff frequency of those woofers. You probably would not have even realized it at the time. Hifi speakers generally don't make good MI speakers..
Well, this is all giving me a bit of a headache! I wish I'd never plugged in that guitar.
I'm seeing DM600s on eBay for as little as £30 (which is a surprise - I paid £180 for mine 15 years ago) so a repair is not really economically viable - I'd be better replacing them and cannibalising for parts as necessary.
Then there's my intended use. I'm in a really small flat at the moment, and have converted most of my CDs to mp3/AAC, so the sound's never going to be great anyway. The DM600s are actually a bit cumbersome in my main room. I also need a pair of studio monitors and was weighing up whether I could use the DM600s for that purpose instead (they're reasonably flat) and get new (and more ergonomic) for the main room.
In all, I need two good sets of speakers. As you might surmise, I'm on a fairly tight budget for this. I'll spend the cash if I have to. On the other hand, I don't like wasting things, and would definitely keep using my DM600s if I could fix them.
I'll try pulling them apart and seeing if I can unravel something from the self-inflicted mess.
I'm seeing DM600s on eBay for as little as £30 (which is a surprise - I paid £180 for mine 15 years ago) so a repair is not really economically viable - I'd be better replacing them and cannibalising for parts as necessary.
Then there's my intended use. I'm in a really small flat at the moment, and have converted most of my CDs to mp3/AAC, so the sound's never going to be great anyway. The DM600s are actually a bit cumbersome in my main room. I also need a pair of studio monitors and was weighing up whether I could use the DM600s for that purpose instead (they're reasonably flat) and get new (and more ergonomic) for the main room.
In all, I need two good sets of speakers. As you might surmise, I'm on a fairly tight budget for this. I'll spend the cash if I have to. On the other hand, I don't like wasting things, and would definitely keep using my DM600s if I could fix them.
I'll try pulling them apart and seeing if I can unravel something from the self-inflicted mess.
I'm surprised that this blew a woofer. I played a Fender Strat through a Threshold T-200 (100 watt class-a) into some scanspeak 8" kevlars once. I played LOUD through them for a few days, but no distorted tones. It sounded remarkably nice.
I wasnt going through any distortion effects. I think I was going through a Conrad Johnson preamp and maybe a reverb pedal.
In general, I concluded back then that you can get some good clean tones from your home stereo. But guitar drivers are made for abuse and tone.
I wasnt going through any distortion effects. I think I was going through a Conrad Johnson preamp and maybe a reverb pedal.
In general, I concluded back then that you can get some good clean tones from your home stereo. But guitar drivers are made for abuse and tone.
I don't think anybody has honestly tried to answered the question "why did the speakers blow". The answer can't be "hi-fi speakers are allergic to guitar". If it were that simple our speakers would explode every time we put on a hendrix album. If you've never heard of the device he's using it's meant to simulate classic guitar amp sounds at line level which can then be sent straight to a recording device, P.A., or amp.
If you destroyed your speaker you simply drove it too hard. Unfortunately speaker ratings are all over the place. When they rate a speaker they try to predict what it will be used for because different kinds of signals can be more or less stressful to the speaker even if they're coming from the same size amp. A heavily distorted guitar signal has a nearly square waveform and very high average level (almost continuous). That's just about the toughest thing you could ask a speaker to handle. Obviously guitar use isn't what B&W had in mind for that speaker or they would have had to rate them more conservatively.
If you're going to match up an amp and speaker for distorted guitar it's best to take the worst case ratings. Take the absolute peak output rating of the amp, usually this fully double it's normal rating. If it can produce a 50watt clean sine wave then it can probably do close to 100w squared right of. Then take the lowest rating of the speaker, not it's peak or "program" or "music rating". Try to find rms or continuous and de-rate somewhat from that to account for the fact that's it's going to be seeing a continuous square wave not a nice sine.
FWIW Marshall traditionally paired it's 50w amps with a speaker that had four drivers rated for a total of 120w, and it's 100w amps with two of those cabinets, the "marshall stack". There are lots of guitar players who get by with less safety margin, but they don't usually use the amp's full power because guitar amp speakers are so efficient.
If you destroyed your speaker you simply drove it too hard. Unfortunately speaker ratings are all over the place. When they rate a speaker they try to predict what it will be used for because different kinds of signals can be more or less stressful to the speaker even if they're coming from the same size amp. A heavily distorted guitar signal has a nearly square waveform and very high average level (almost continuous). That's just about the toughest thing you could ask a speaker to handle. Obviously guitar use isn't what B&W had in mind for that speaker or they would have had to rate them more conservatively.
If you're going to match up an amp and speaker for distorted guitar it's best to take the worst case ratings. Take the absolute peak output rating of the amp, usually this fully double it's normal rating. If it can produce a 50watt clean sine wave then it can probably do close to 100w squared right of. Then take the lowest rating of the speaker, not it's peak or "program" or "music rating". Try to find rms or continuous and de-rate somewhat from that to account for the fact that's it's going to be seeing a continuous square wave not a nice sine.
FWIW Marshall traditionally paired it's 50w amps with a speaker that had four drivers rated for a total of 120w, and it's 100w amps with two of those cabinets, the "marshall stack". There are lots of guitar players who get by with less safety margin, but they don't usually use the amp's full power because guitar amp speakers are so efficient.
Another thing i've noticed when using a Hi-Fi as a guitar amp..
Anytime you bump a string the woofers will JUMP..You can watch them moving in and out quite far.. a nice "thump" on a guitar string could blow your woofers right across the room...
You can get some very low frequencies outta there,nearing DC.
Musical Instrument speakers have a much stiffer surround,and don't seem to move a whole lot with low frequency signals..
Anytime you bump a string the woofers will JUMP..You can watch them moving in and out quite far.. a nice "thump" on a guitar string could blow your woofers right across the room...
You can get some very low frequencies outta there,nearing DC.
Musical Instrument speakers have a much stiffer surround,and don't seem to move a whole lot with low frequency signals..
what you have to realise is that the construction of PA driver is different. They purposely limit excursions but using stiff and very strong surrounds.
Think about it... rubber surrounds on HiFi can stretch.it is their purpose.. they try to maintain linearity.
The cloth surrounds on PA speakers do not stretch (much), so when you hit the end of surround travel, they stop.. dead.... hence protecting the voice coil from over excursion !!!
often we tend to think of the cloth surround as a trade-off for higher efficiency, where in actual use it is what protects a PA driver from the massive transients that a guitar can provide, but compressing the sound level in the process.
Once recorded, these transients are , by nature of LP, CD, microphones, compressors etc etc , limited to a maximum value, hence the hifi driver is not generally subjected to them.
I might add that this is one reason that it is so hard to realise a "live" sound in a home system
Think about it... rubber surrounds on HiFi can stretch.it is their purpose.. they try to maintain linearity.
The cloth surrounds on PA speakers do not stretch (much), so when you hit the end of surround travel, they stop.. dead.... hence protecting the voice coil from over excursion !!!
often we tend to think of the cloth surround as a trade-off for higher efficiency, where in actual use it is what protects a PA driver from the massive transients that a guitar can provide, but compressing the sound level in the process.
Once recorded, these transients are , by nature of LP, CD, microphones, compressors etc etc , limited to a maximum value, hence the hifi driver is not generally subjected to them.
I might add that this is one reason that it is so hard to realise a "live" sound in a home system
A common mistake is to assume a guitar can't blow your speaker just because you hear guitar on records. No, No and No! You can blow any speaker with a right type of signal. One important factor in both mastering and mixing processess is to get rid of all the nasty stuff in the recorded signal that would be fatal to your speakers. Muted string riffs, high pitch squeal, transients spikes, low notes and close to square wave distortion is surely fatal to your speakers and it is attenuated (or otherwise processed to be more speaker friendly) on records. If this is not done in the mastering or mixing process even records can be fatal to your speaker system. The frequency and dynamic range of a normal CD is suffient to contain very hazardous material. It's the content that matters.
An instrument (or pro audio speaker) has to be more rugged to withstand the abuse of "abnormal" signal sources (or distorting amplifiers), therefore they usually have: a) voice coils that handle more power (sometimes they even sport a construction that cools down the voice coil with airflow), b) voice coils with less winding at the ends. (This slows down the cone movement making the speaker more tolerant against transients).
Edit: Looks like Andy got a bit ahead of me.
An instrument (or pro audio speaker) has to be more rugged to withstand the abuse of "abnormal" signal sources (or distorting amplifiers), therefore they usually have: a) voice coils that handle more power (sometimes they even sport a construction that cools down the voice coil with airflow), b) voice coils with less winding at the ends. (This slows down the cone movement making the speaker more tolerant against transients).
Edit: Looks like Andy got a bit ahead of me.
I'm aware guitar on a record has been compressed and limited in the mastering process. Have you noticed yet that he's not plugging a marshall into his speakers but what is essentially a synthesizer that tries to reproduce those recorded sounds? It's a line level digital modeling box that attempts to model not only amps but speaker cabinets and even different microphones used to record them. Granted it's probably still not as smooth as an album, but all I'm saying is there's no point in throwing up your hands and crying "no, no, there's no way you can play guitar through anything but a guitar speaker". A signal is a signal, an amp is an amp, and if you're willing to think about what kind of signal you're producing and at what power level it's possible to safely match a speaker to it.
The lowest string on a guitar is about 80hz if you're using standard tuning, how do you get "low frequencies, almost DC" out of one?
That makes it sound like there's some magic signal that will make a 5w single ended tube amp blow a 300w speaker. What I'm trying to point out is: "You can NOT blow a speaker, with any type of signal, if you safely match the amp and speaker for the WORST CASE signal the amp can produce. There's an absolute maximum power signal an amp can produce that's limited by it's power supply voltage. Get a speaker that can handle this or a less powerful amp and you can play all the guitar you want.
The type of pro audio drivers teemuk describes are very uncommon in guitar amps. Some people do use electrovoice drivers or other PA style drivers, but these can't produce the sound most guitar players like. The vast majority are 12" paper cone fullrange drivers that have changed little since 1960. These are essentially old style radio speakers with all their ugly break up modes and ragged frequency response. They color the sound and that's what musicians want. The most common voice coil rating is 30w. Newer speakers may be as much as 80w, but one of the most popular all time speakers, the celestion blue, is 15w. Guitar players have traditionally dealt with this by using multiple drivers to build up a cabinet that can cope with anything their amp can dish out.
The lowest string on a guitar is about 80hz if you're using standard tuning, how do you get "low frequencies, almost DC" out of one?
That makes it sound like there's some magic signal that will make a 5w single ended tube amp blow a 300w speaker. What I'm trying to point out is: "You can NOT blow a speaker, with any type of signal, if you safely match the amp and speaker for the WORST CASE signal the amp can produce. There's an absolute maximum power signal an amp can produce that's limited by it's power supply voltage. Get a speaker that can handle this or a less powerful amp and you can play all the guitar you want.
The type of pro audio drivers teemuk describes are very uncommon in guitar amps. Some people do use electrovoice drivers or other PA style drivers, but these can't produce the sound most guitar players like. The vast majority are 12" paper cone fullrange drivers that have changed little since 1960. These are essentially old style radio speakers with all their ugly break up modes and ragged frequency response. They color the sound and that's what musicians want. The most common voice coil rating is 30w. Newer speakers may be as much as 80w, but one of the most popular all time speakers, the celestion blue, is 15w. Guitar players have traditionally dealt with this by using multiple drivers to build up a cabinet that can cope with anything their amp can dish out.
poptart said:
I still hold my opinion that it's not about the device feeding the speaker - it's about the signal. His power amp is a power amp as much as the output stage of a Marshall would be. At the end, his trying to produce a similar signal with the speakers as he would try with a Marshall (or any amp he prefers). Granted that with low power the speakers can handle pretty much anything, but how many people actually play guitar with low power - especially when they use (inefficient) hifi drivers. The guitar signal also contains a lot of transients; power peaks exist even when the volume is turned low.
This might be the base frequency of the lowest note but not necessarily the lowest frequency the guitar can produce. The resonance peak of speakers is typically somewhere in between 60-100Hz. Some amp-speaker combinations have difficulty of handling palm muted riffs without excessive "farting". At those times i'm glad I had an instrument speaker plugged at the end of the speaker coord. Also, a square wave is not uncommon signal for guitar players who prefer "fuzz" tones. When you look at the form of square wave you see what voice coil consideres as "DC" at it's tops and bottoms. Whatever the frequency, this will heat up the voice coil some amount.
A 5W single ended amp will do it's best in trying to blow a 300W speaker when it outputs transient spikes or square wave distortion at low frequency. Take a higher power amp and lower power speaker (a more typical combination after all, don't you agree) and the chance of blowing the speaker increases even more. Considering all the nasty stuff that may occur in the guitar signal (coupled with the requirement for large sound pressure levels) the power requirement is better met when using instrument speakers designed for the job.
I have an Average knowledge of amps, speakers, guitars and such, but from what has been said here completely contradicts what i've always been told.
What I always hear is that you should (theoretically) have a more powerful amp than your speakers so when you turn it up really loud clipping doesn't occur, which is really bad. The opposite has been said here (or is this just if you happen to plug a guitar straight in.
That said, how easy is it to destroy a set of speakers with a CD (anything other than plugging a guitar right into it.) And can clipping do that much damage? And is clipping as much of a problem of higher end (Rotel - what i've got and always try to get in an amp.) amps?
As a bass player myself, and being interested in making my own bass cabinet - would using, say, subwoofers with massive Xmax (rubber roll surround) be bad. Should I go the cloth surrounds? and will i blow an electric amp if I plug in a bass?
Cheers, Nic.
PS: sorry if I got a bit off topic
What I always hear is that you should (theoretically) have a more powerful amp than your speakers so when you turn it up really loud clipping doesn't occur, which is really bad. The opposite has been said here (or is this just if you happen to plug a guitar straight in.
That said, how easy is it to destroy a set of speakers with a CD (anything other than plugging a guitar right into it.) And can clipping do that much damage? And is clipping as much of a problem of higher end (Rotel - what i've got and always try to get in an amp.) amps?
As a bass player myself, and being interested in making my own bass cabinet - would using, say, subwoofers with massive Xmax (rubber roll surround) be bad. Should I go the cloth surrounds? and will i blow an electric amp if I plug in a bass?
Cheers, Nic.
PS: sorry if I got a bit off topic
poptart said:
When you pull the string and release it, it moves across the pickup and generates a very large voltage before it settles down into resonating.
You can observe this (if you're reckless and curious enough) by damping the strings and pushing them with the heel of your hand while watching the cone move at much less than 80Hz, more like 10 if the amp allows it.
psychocow21 said:
No it doesn't. The "DC" in clipped signal is fatal to the speakers. A more powerful amp would not clip as easily but with guitar effects (or deliberate overdriving of the amp) the signal the amp outputs can be made to produce similar sounds. The guitar signal also contains transients which can clip or push the speaker cone too much unless they are limited somehow. For instrument amps you actually need speakers that can handle both types of abuse.
The content of the CD is what matters: If the content is low frequency square wave signal - or perhaps similar sounds that CD produces when the laser has difficulties to read the track - your speakers will not last very long. The example was quite exaggerated but I hope it demonstrated that a right signal content can be hazardous to speakers. Another example; I blew a midrange and tweeter from my 120W hifi speakers with 75W amp just because the amp distorted. One speaker I blew with low freq content (a sine wave bass track on a CD mixed crappily by myself) that literally tore the speaker cone from the frame. It actually reproduced very well (at low sound pressure level) until the cone just started buzzing annoyingly and I discovered the damage.
By the way, these links are worthwhile reading for anyone interested about the topic of this thread.
http://www.rane.com/pdf/old/note128.pdf
http://users.chariot.net.au/~gmarts/ampshow.htm
http://www.colomar.com/Shavano/speaker_design.html
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.