Loss of volume and tone was destroyed!

magnanimous66 said:
Blown speakers
Click to expand...
I've never blown a speaker. Do you think they were blown prior to using this set up or do you think it happened while trying to get your sound figured out with the Ax8 rig? In my mind, I'm picturing a speaker making a 'boom' noise or something to inform me it's been blown.

I ask this because I've got a 4x12 cab with some really low fidelity speakers that used to sound great paired with my old '73 50watt Marshall. I've been considering buying a Power Station or other SS amp to fuel the cab and use my AxeFx3. I'm wondering if proceeding slowly with caution will is good enough or if I'm gonna blow the speakers from the get go by pairing a 4ohm-80watt cab with 200plus watt SS amp. Like, could the signal alone blow it even without loud volume? I'm a bit ignorant about this.

Look forward to hopefully hearing you get it worked out and in tone heaven soon. I loved my AX8.
 
Bman said:
I've never blown a speaker. Do you think they were blown prior to using this set up or do you think it happened while trying to get your sound figured out with the Ax8 rig? In my mind, I'm picturing a speaker making a 'boom' noise or something to inform me it's been blown.

I ask this because I've got a 4x12 cab with some really low fidelity speakers that used to sound great paired with my old '73 50watt Marshall. I've been considering buying a Power Station or other SS amp to fuel the cab and use my AxeFx3. I'm wondering if proceeding slowly with caution will is good enough or if I'm gonna blow the speakers from the get go by pairing a 4ohm-80watt cab with 200plus watt SS amp. Like, could the signal alone blow it even without loud volume? I'm a bit ignorant about this.

Look forward to hopefully hearing you get it worked out and in tone heaven soon. I loved my AX8.
Click to expand...
I don't think the speaker were blown previously. While trying to sort things out out, while playing I did hear a subtle volume decrease twice. I assume the subtle signal loss was individual speakers failing. This of course is an assumption. The next day I disconnected all the wires to the speakers and read the speaker ohms with an electrical meter. Typically you should read about 12 ohms on a 16 ohm rated speaker. The reading I got on all 4 speakers were fluctuating high ohms reading.
My solution is to install 4,150 watt 16 ohms speakers, combined my cabinet will be able to handle 600 was max. So if the output of the Matrix power amp is 500 watts and I use the 4 ohms input on my cabinet and since my cabinet can handle 600 watts max I should be safe from blowing the speakers. I think?
I believe your cabinet needs to have the ability to handle the max wattage output of your head/power amp. For example if you have a 80 watt max cab and your power amp is 200 watt max and you play at high volume I would expect a failure.
If my understanding is incorrect someone please correct me.
 
[edited after rethinking ancient consumer stereo lore and not wanting to derail the thread with debate]

all this discussion of impedance, wattage, and blown speakers without clarity on the wiring including parallel vs series… hesitant to recommend anything further. “measure twice, cut once.”
 
Last edited:
Trying to judge safe output wattage by volume is not a good idea. Our hearing is logarithmic, so a small difference in volume can equate to a fairly large difference in wattage. A 3 dB increase equates to roughly twice the output wattage. You can easily overload the speakers when trying to get just a little more output if they are not adequately rated.

Safest bet is to use a speaker load that is rated at or above the output capacity of the amp that is driving it. Underpowering speakers is largely a myth used to sell bigger amps. There is no way to underpower a speaker. If that were true, turning down the volume would damage speakers and that's clearly not the case. Pushing an underpowered amp too hard will cause the amp itself to distort, which generates extra harmonics. In some specific conditions excessive distortion can cause damage to high frequency drivers, but that's more of a concern with full range applications like a PA system or car audio. With guitar speakers this is completely a non-issue since we constantly bombard them with tons of distortion from the amp. The raw output of a cranked high gain tube amp has massive amounts of distortion and high frequency harmonics yet properly rated guitar speakers take it all in stride with a smile.
 
Last edited:
magnanimous66 said:
I don't think the speaker were blown previously. While trying to sort things out out, while playing I did hear a subtle volume decrease twice. I assume the subtle signal loss was individual speakers failing. This of course is an assumption. The next day I disconnected all the wires to the speakers and read the speaker ohms with an electrical meter. Typically you should read about 12 ohms on a 16 ohm rated speaker. The reading I got on all 4 speakers were fluctuating high ohms reading.
My solution is to install 4,150 watt 16 ohms speakers, combined my cabinet will be able to handle 600 was max. So if the output of the Matrix power amp is 500 watts and I use the 4 ohms input on my cabinet and since my cabinet can handle 600 watts max I should be safe from blowing the speakers. I think?
I believe your cabinet needs to have the ability to handle the max wattage output of your head/power amp. For example if you have a 80 watt max cab and your power amp is 200 watt max and you play at high volume I would expect a failure.
If my understanding is incorrect someone please correct me.
Click to expand...

I assume people use a Matrix or SD Power Stage to power 2x12 guitar cabs. You mentioned you have a 1960A (4x12). Aren't people pushing guitar cabs with SS amps? The SS amps are almost always high watt output. I need to go back and re-read this thread because I feel like I'm missing something. I mean what's a common way to run the AxeFx to a guitar cab and not using an IR? Isn't it a SS amp so the tone isn't colored the usual preference?

Again, pardon my ignorance. I thought I had my head easily wrapped around this one. Not your situation of course. Just the concept of pushing a guitar cab with a higher power SS amp.
 
Bman said:
I assume people use a Matrix or SD Power Stage to power 2x12 guitar cabs. You mentioned you have a 1960A (4x12). Aren't people pushing guitar cabs with SS amps? The SS amps are almost always high watt output. I need to go back and re-read this thread because I feel like I'm missing something. I mean what's a common way to run the AxeFx to a guitar cab and not using an IR? Isn't it a SS amp so the tone isn't colored the usual preference?

Again, pardon my ignorance. I thought I had my head easily wrapped around this one. Not your situation of course. Just the concept of pushing a guitar cab with a higher power SS amp.
Click to expand...
I run Matrix GT1000FX stereo into two 60Watt 8ohm V30 cabs. So each cab has the potential of receiving 325 Watts from the amp (more than enough to fry them I suspect) IF I was to crank the Matrix with a healthy input. This is something I would not purposely do, but still, I am going against the Matrix manual's advice which clearly states that the cab's power rating should be higher than what's fed to it to ensure no possibility of cab damage. I suspect many are living dangerously this way since many better quality SS power amps recommended for modelling are of higher wattage. I've been careful for many years now and never accidently blown a speaker (basement hacker @ lower volume usage), tho I do sometimes wonder if those pops I sometimes hear on power up / shut down are quick 325W spikes that could be doing cab damage.
 
Last edited:
The problem is knowing where in the amp's output range the "safe" range ends. Due to the logarithmic nature of audio volume, the wattage goes up way faster than the dB's. The difference between your cab's 60 watt rating and the amp's 325 watt rating amounts to only about 7 dB of power difference. Not as much as many might expect. For comparison, a 10 dB increase in power is twice as loud. Exceeding the speakers rating by a full 100% (120 watts) would amount to only 3 dB of volume difference. It's easier to overdo it than many people think.

Using a good SPL meter might give you a rough idea of the amp's power output if measured correctly. Vintage 30's have a 100 dB sensitivity (with 1 Watt 1 kHz sine wave input measured at 1 meter away), so they don't take much power to get ear splittingly loud. At 60 watts they would be outputting roughly 118 dB. In theory, if you never exceed 118 dB of SPL from one at 1 meter away, you should be within the V30's rated range. That said, speakers are not perfectly linear in the way they react to power input and other factors like room reflections can skew your measurements so you might still want to err on the side of caution with such measurements. Keep in mind this also applies only to measuring single speakers, since multiple speakers in a cab would have a different combined SLP at various frequencies.
 
mr_fender said:
The problem is knowing where in the amp's output range the "safe" range ends. Due to the logarithmic nature of audio volume, the wattage goes up way faster than the dB's. The difference between your cab's 60 watt rating and the amp's 325 watt rating amounts to only about 7 dB of power difference. Not as much as many might expect. For comparison, a 10 dB increase in power is twice as loud. Exceeding the speakers rating by a full 100% (120 watts) would amount to only 3 dB of volume difference. It's easier to overdo it than many people think.

Using a good SPL meter might give you a rough idea of the amp's power output if measured correctly. Vintage 30's have a 100 dB sensitivity (with 1 Watt 1 kHz sine wave input measured at 1 meter away), so they don't take much power to get ear splittingly loud. At 60 watts they would be outputting roughly 118 dB. In theory, if you never exceed 118 dB of SPL from one at 1 meter away, you should be within the V30's rated range. That said, speakers are not perfectly linear in the way they react to power input and other factors like room reflections can skew your measurements so you might still want to err on the side of caution with such measurements. Keep in mind this also applies only to measuring single speakers, since multiple speakers in a cab would have a different combined SLP at various frequencies.
Click to expand...
Well stated - since I play quietly (max apprx 80dB max @1m (measured with a meter every once in a while)), I'm pretty confident I'm well below the threshhold (barring an accident 😳), but those gigging / practicng with others in actual venues / rehearsal spaces are far more likely to blow out their low rated cabs paired with higher rated amps when trying to adjust by ear and stay within the safe range due to the difficulties of perception you mention. For those folks, it seems best to follow the manual's advice and have the cab rated above the amp.

Curious tho - what do you think about the on/off pops in a config like mine - are my 8ohm 60W V30s at risk from the quick pop I hear when the Martrix running in parallel turns off? (the pop isn't loud so I didn't much worry but ...)
 
Last edited:
The pops can cause damage if they are loud enough. They are very short in duration though, so the risk is different than extended overpowering, which causes the voice coil to overheat. General rule of thumb for power amps is turn them on last and turn them off first to avoid such pops.
 
You must log in or register to reply here.
Back
Top Bottom