The Canadian Guitar Forum banner
1 - 19 of 19 Posts

·
Premium Member
Joined
·
910 Posts
Discussion Starter · #1 ·
So, to make a short story long, I've recently started experimenting with different Eminence speakers, as they're relatively cheap and easy to obtain. Since I bought a few models new, I thought it was unfair to judge them before they were actually broken in. I can't put 100 hours of loud playing on each speaker, so I thought I would fast track the process, as I already own a variac. I read online about the "Weber formula" to calculate how much voltage can safely be sent through a speaker. Luckily for me, I researched enough to find an online forum discussion in which Jim from Scumback speakers mentioned it wasn't safe to put more than 12V on a speaker, and more voltage can fry the voice coil. I emailed Jim and he was nice enough to reply about 10 minutes later confirming this.

His method is:
9V (less if really low power speaker) for low wattage speakers with light doping for ± 16 hours
Up to 12V for high power speakers with heavy doping during 32-48 hours
Cycles of 2 hours on / 1 hour off

So I did exactly that with various speakers
You can see on following pictures (sorry for the bad quality and gym setting):
- Timer (for swimming pool I guess) programmed for 2 on / 1 off
- Variac set a 9-12V (measured with digital multimeter as the dial is not precise)
- 2 speakers boxes which are just a tad higher than the actual speaker(s)
- Construction foam around the speaker (no direct contact) to muffle the noise

It's possible to run many speakers in parallel without changing the voltage, as long as both speakers can handle said voltage, if different models. The 60 Hz hum produced really is loud, but in a closed basement room, it's barely noticeable, depending in what room you are in the house. I personally ran each speaker for 40 hours (2 1/2 days). Next step is getting a brand new model and A/B'ing it with a broken-in one (more on that later)

Room Furniture
Machine Machine tool Tool
 

·
Premium Member
Joined
·
3,618 Posts
I am assuming you are talking AC; sustained 9V DC will blow a speaker in under a minute. Even AC, 9V seems high - 1 watt = 2.83V @ 8 ohms... so 9 is about 10 watts; not dangerous, but also unnecessary.

I would not recommend this method personally; program material is best. Doesn't have to be loud, just sustained. You can prematurely fatigue a speaker by making it work too close to it's limits (in a sustained sort of way vs transient) before it's broken in.
 

·
Premium Member
Joined
·
910 Posts
Discussion Starter · #4 ·
DC would only move the cone in one direction and not back and forth; wouldn't be any use

As far as music goes, I'd be more worried about lower frequencies (kick drums, bass, etc.) messing up the speaker than 60 Hz
Also, you can't run loud music non-stop, including while you're sleeping ;)
 

·
Premium Member
Joined
·
3,618 Posts
DC would only move the cone in one direction and not back and forth; wouldn't be any use

As far as music goes, I'd be more worried about lower frequencies (kick drums, bass, etc.) messing up the speaker than 60 Hz
Also, you can't run loud music non-stop, including while you're sleeping ;)
Yes, and then blow the speaker. You can fry a unit with a 9 volt battery. Not everyone knows that so I was just making it clear so nobody buggers their stuff for no good reason.

Most program content is above 60 Hz; in fact pop/rock music has very little below that usually. One could always use a bass rolloff if one was concernned (most MP3 players or hifi sets have some EQ that could be u7sed for that, but at 1-2 watts), I never bother. IMHO break in should happen with full bandwidth, complex signal.
 

·
Occasional CEO
My Superstrat
Joined
·
1,995 Posts
Note that guitar speakers are rarely spec'd below 80Hz. 60Hz is below what would be considered "safe" for a guitar speaker (under prolonged use), let alone a "good" thing by any stretch. In fact, running signals outside the speakers' natural response for long periods of time can void the warranty! Food for thought.

While I absolutely admire the DIY ingenuity, I can't endorse the result in this case.

Pink noise at 1/3 power within the manufacturer's specified frequency range is best IMO. But there are a variety of methods.

*Edited: Fixed typo and added comment in brackets
 

·
Premium Member
Joined
·
910 Posts
Discussion Starter · #9 ·
Note that guitar speakers are rarely spec'd below 90Hz. 60Hz is well below what would be considered "safe" for a guitar speaker, let alone a "good" thing by any stretch. In fact, running signals outside the speakers' natural response for long periods of time can void the warranty! Food for thought.
I'll quote Eminence:

" We often use a noise signal generator at 20Hz with enough current to get the speaker moving smartly for a few hours, but without abusing it."
 

·
Occasional CEO
My Superstrat
Joined
·
1,995 Posts
I'll quote Eminence:

" We often use a noise signal generator at 20Hz with enough current to get the speaker moving smartly for a few hours, but without abusing it."
They likely do that at a small fraction of the speaker's power rating. You'd have to confirm with them, but I doubt they even get up to 10% of the rated power. Perhaps even 1W or less.

You should also know, they are the ones who deny warranty claims if speakers are deemed damaged by too much low frequency use.
 

·
Premium Member
Joined
·
910 Posts
Discussion Starter · #11 ·
They likely do that at a small fraction of the speaker's power rating. You'd have to confirm with them, but I doubt they even get up to 10% of the rated power. Perhaps even 1W or less.

You should also know, they are the ones who deny warranty claims if speakers are deemed damaged by too much low frequency use.
I'm also running the variac at a very small percentage of the speaker's power rating ;)

Have you had lots of returns for blown speakers from 7 string guitar players?
The low B string on a 7 string is ± 62 Hz...
How about 8 string players?
 

·
Premium Member
Joined
·
3,618 Posts
Dude, guitar speakers resonant frequency is in the 65 to 85 hz range. Most are 70- 75 hz and a low E is 82.2 Hz. Easily safe down to that. People use guitar speakers for bass ( granted not at the same power handling) and that bottoms out at 41.1 Hz. Reconers sweep 20 to 20K to test no matter the speaker type ( they just do it at very low power). Not a problem.

There's no way for them to know that speaker damage was was caused by excessive low frequency content, not in any conclusive way. A fried voice coil is a fried voice coil. A cone can be fatigued not just by lows but also by heavy distortion or over powering in general.
 

·
Occasional CEO
My Superstrat
Joined
·
1,995 Posts
I'm also running the variac at a very small percentage of the speaker's power rating ;)

Have you had lots of returns for blown speakers from 7 string guitar players?
The low B string on a 7 string is ± 62 Hz...
How about 8 string players?
Most people playing 7 and 8 string guitars have very little low frequency in their tone because it just muddies up the sound. The ones who want that kind of low end often turn to bass speakers (much to the dismay of any live sound engineer).

I'm just relaying how Eminence handles warranty claims. Low power is the key if you're running low frequencies. If you ever try to do a warranty claim with a speaker that you've played "excessive bass" through (Eminence's wording), expect the claim to be denied.
 

·
Premium Member
Joined
·
910 Posts
Discussion Starter · #14 ·
Most people playing 7 and 8 string guitars have very little low frequency in their tone because it just muddies up the sound. The ones who want that kind of low end often turn to bass speakers (much to the dismay of any live sound engineer).

I'm just relaying how Eminence handles warranty claims. Low power is the key if you're running low frequencies. If you ever try to do a warranty claim with a speaker that you've played "excessive bass" through (Eminence's wording), expect the claim to be denied.
Info is appreciated
I know you're just trying to prevent people that don't know what they're doing from blowing up their stuff
Owning a store (which I very much like BTW), I know you want to avoid returns, headaches and the likes

So far so good on my end
Part of this post is to warn people from the Weber formula circulating on the web
IE, this formula concludes that I could have run 16 ohm Eminence Tonkers (150W) at a whopping 28 V
I only used 12V, and I don't think I'd go above that for a 12" speaker
I trust Jim Seavall (Scumback) and his expertise on the matter
 

·
Occasional CEO
My Superstrat
Joined
·
1,995 Posts
Dude, guitar speakers resonant frequency is in the 65 to 85 hz range. Most are 70- 75 hz and a low E is 82.2 Hz. Easily safe down to that. People use guitar speakers for bass ( granted not at the same power handling) and that bottoms out at 41.1 Hz. Reconers sweep 20 to 20K to test no matter the speaker type ( they just do it at very low power). Not a problem.
Quick sweeps are very different than a constant signal maintained for hours.

There's no way for them to know that speaker damage was was caused by excessive low frequency content, not in any conclusive way. A fried voice coil is a fried voice coil. A cone can be fatigued not just by lows but also by heavy distortion or over powering in general.
I would agree, but I've seen it happen several times. Customer tries to start the warranty process, and Eminence comes back with, "That happens because of excessive low frequencies. Not covered under warranty."

Just trying to give people a heads up.
 

·
Premium Member
Joined
·
976 Posts
Yes, and then blow the speaker. You can fry a unit with a 9 volt battery. Not everyone knows that so I was just making it clear so nobody buggers their stuff for no good reason.

Most program content is above 60 Hz; in fact pop/rock music has very little below that usually. One could always use a bass rolloff if one was concernned (most MP3 players or hifi sets have some EQ that could be u7sed for that, but at 1-2 watts), I never bother. IMHO break in should happen with full bandwidth, complex signal.
Once on the Hiwatt Convention Forum ,.........I asked if I could do the 9v batterie test
on a driver and Mark Huss said not to do this so you are probably right when you say that it's dangerous to do this !
 

·
Premium Member
Joined
·
3,618 Posts
It`s dangerous if you give it sustained 9V DC. If you make only momentary contact, that is the default method for figuring out which speaker terminal is the + when in the field . Problem is most guys forget the momentary part the first time they try it so some people, such as Mark, may advise against it altogether for general safety.
 

·
Registered
Joined
·
12,111 Posts
I once read in a Warren Haynes interview where he said he would connect a cd player (this was almost 2o years ago) to a new 4x12 cabinet and just let it play through that for a month or so at listening volume to break in the speakers.

I can't verify how true that is, but I remember reading it.
 
1 - 19 of 19 Posts
Top