What is causing me to blow speakers?

[Alex_C]

That's really interesting. I always thought that way about speakers, too. I even had the thought that maybe i should just get a 200 watt speaker so I'll make sure not to blow it. But evidently that thinking isn't right. The tech told me with a 15 watt amp I'd be much more likely to blow a 75 watt speaker than a 20 watt speaker. Honestly, I don't understand it...

I asked the tech and he responded promptly and said:

“All the speaker output jacks do is divert the existing speaker wiring to a tap point where you can take them out to other cabinets. There's no other circuit interaction involved and no other circuit modifications made or required to do that. The theory of the mod is that when you plug into the speaker out, the internal speaker is disconnected by a switching lug and the tip and sleeve contacts of the jack becomes your speaker lead to whatever cabinet you choose..”

He seems to be dismissing outright the possibility that there could be current going to the speaker due to the speaker out mods. Instead, he thinks cranking 15 watt amps into 65 (et65) & 75 watt (eminence 15) speakers could be my problem. The green beret is a 25 watt speaker though. Why’d it blow? He also asked if I was using fuzzes and distortions, as if that was maybe the problem. But I’ve used boosts, overdrives, distortions, and fuzz pedals with these amp for years without problems.

The argument that a low wattage amp will blow a high wattage speaker is odd. The only thing I could think of is heat. If a speaker doesn't move enough, the voice coil could overheat. I've never encountered this, I have a 5 watt amp running into a 75watt speaker with no issues.

 

[Derrick]

Both amps were plugged into all three of those cabs.

Since we are not there physically to see what you mean, lets please clarify this statement. Were you connecting more than one amp to a cabinet or more than one cabinet to an amp, or did you only ever have just one amp connected to just one speaker cabinet?

I think you may have blown output transformers and not speakers. If your "tech" wired things wrong he may have left the speaker out "open", which means your output transformer is not seeing a load.

I recently blew a transformer in a tube amp. Now it sounds fine at low volumes, but when I push the amp, it farts out and the volume reduces. It's not the tubes and I am a former tech with familiarity in customer repairs. So... if it is your transformer, when you tried the next speaker, it would have sounded bad right away. But if it's the speaker, the next one might have sounded fine for a bit before the 2nd then blew out. Which was it?

 

[printer2]

The argument that a low wattage amp will blow a high wattage speaker is odd. The only thing I could think of is heat. If a speaker doesn't move enough, the voice coil could overheat. I've never encountered this, I have a 5 watt amp running into a 75watt speaker with no issues.

It all started with hifi amps. Too low a wattage and stupid people cranking them blew tweeters. So in that case a lower wattage amp can destroy speakers.

 

[ficelles]

Make sure you are using speaker cables and not instrument cables.

I remember trying to explain why to a friend who is a fantastic guitarist but not technically minded... I did not succeed

 

[ficelles]

The argument that a low wattage amp will blow a high wattage speaker is odd.

It's a persistent myth... it comes from the whole myth that "underpowering" a speaker cab means you turn the amp up so much it goes into square wave clipping, and then there's the additional myth that square wave clipping equals DC.

Misconceptions both, and I'd challenge anyone with a low-wattage amp to try and blow my 800 watt Mesa bass cab

On the other hand, cranking an amp while pushing the preamp hard with pedals can result in the amp putting out way more than its stated maximum power...

 

[2after909]

Since we are not there physically to see what you mean, lets please clarify this statement. Were you connecting more than one amp to a cabinet or more than one cabinet to an amp, or did you only ever have just one amp connected to just one speaker cabinet?


I recently blew a transformer in a tube amp. Now it sounds fine at low volumes, but when I push the amp, it farts out and the volume reduces. It's not the tubes and I am a former tech with familiarity in customer repairs. So... if it is your transformer, when you tried the next speaker, it would have sounded bad right away. But if it's the speaker, the next one might have sounded fine for a bit before the 2nd then blew out. Which was it?

Yes, I’m using speaker cables and not instrument cables.

I meant that I was mixing and matching heads and cabs, just auditioning them for sounds. I was never using more than one head s d one speaker at a time.

 

[PhredE]

Just a kind suggestion to OP:

Consider buying a sacrificial testing speaker you can pop into a combo/speaker box and use solely as a test? Burning up a $20 test speaker is so much less painful than a good ET65, Emi 15 or the like.

Parts Express has quite a few that should work ok for such a purpose: (just one possibility I found in a brief search):

Loading…

www.parts-express.com

The sensitivity rating is very low; so it will seem 'quiet' at amp volume -- but, impedance, power rating, even frequency response etc. should work just fine.

Edit: Also, just thought of it-- you should first check resistance on each of those speakers, then (if they appear to be within stated spec ~= 8 ohms nominally..) then test them with a separate amp / amp head.
It is possible they are not blown -- you say they are, but based on what exactly? Have you taken a measurement from your DMM across the leads? 'Cold' unenergized resistance for a '8 ohm' speaker should generate a reading something like 6.5-8.0 ohms. If you haven't checked them, please do it and post back to let us know.

 

[printer2]

Or a full range speaker from a thrift store.

 

[Lone_Poor_Boy]

-Haven't blown a speaker ever at age 49
-Have now blown 4
-Recently had three main amps serviced

I just have to assume you don't have much experience with random troubleshooting to have got to two blown speakers and not just assumed it is an issue with the work that was done, then to get to four and still be asking what it might be.

One tip for the future that I used often at my work where unusual events could happen due to all the different dynamics happening in the complex facilities I ran. I tried to train staff to always think this way as it is so simple;
When something is happening for the first time, ask yourself..... what are we doing differently for the first time? Or..... what have we recently changed?

The key is the simple acknowledgment that you may have no idea; that you can't possibly see a connection at first glance. But trust the statement and pursue it and you will find it.

Reminds me a bit of when my power supply(PSU) blew on my PC. I replaced the PSU and then found two of four hard drives fried. So I replaced a hard drive, and it fried. So I replaced that one and it fried. At that point I realized I should stop doing that. It turns out some of the SATA connecting ports got whacked when the PSU fried, and I had to replace the motherboard.

The primary problem was my inability to competently troubleshoot the motherboard electronics instead of just swapping another part in.

Back to your issue; it is an issue with the work that was done.

 

[Mleffler1]

Back to your issue; it is an issue with the work that was done.

It’s just too much of a coincidence that your speakers started to blow soon after you had work done to your speaker jacks in those amps.

I have been playing out since 1968 and I have never once blown a speaker.

 

[King Fan]

@2after909 , as you'll know, longer threads start recirculating. Suggestions, questions, and (sorry) criticisms start to come around over and over, like logs in a whirlpool. People are busy. Reading threads takes time.

One thing that may end the cycle (for respondents who read *any* post before theirs) is when the OP takes some definitive action. "I've decided to use my amps as lawn ornaments" or "I took up Zoroastrianism" or "I'm taking my amps and speakers for a checkup."

 

[JustABluesGuy]

I’m still curious how a speaker can be blown and later sound “normal” and even fine for a while then go out again.

 

[King Fan]

Good thought. I don't know much about blown speakers *or* OTs, thank heaven, but when a diagnosis doesn't make sense, one cause of confusion could be that something else is causing the symptoms....

 

[2L man]

Measure if there is DC voltage on output jack output?

If you have a multimeter this take about a minute. If amp has more than one output connect another cable to it and measure there. Lay it to floor and press MM probes down and you don't have to touch plug hot. If amp has only one output use somekind jack/plug splitter.

 

[omahaaudio]

Motivational speakers?
(Thank you Doug Stanhope)

 

[Peegoo]

Make sure you are using speaker cables and not instrument cables.

In the pics provided, the wire from the amp to the speakers appears to be at least 18ga stranded pair, which is perfectly fine.

 

[PhredE]

Speaking from hard-earned personal experience.. (uh-hum, coughs, turns red, clears throat..) I think the question was about the connection from [newly installed] jack-> cable-> [external] speaker, (if used), maybe not just the internal wiring to the installed jack itself.

It's kinda curious that the tech used two different types of jacks in the 2 mods.
If the jack was not functioning properly for whatever reason, that would be an obvious problem. I guess all we can do is assume it is good hardware and was installed right.

I have toasted a perfectly good amp transformer by not having the cable plugged in when powering up/on, (yes, I admitted that in public -- but, but, that was when 'I was much younger and much more stupider!') -- eg; no load on output side. In my case, the amp *appeared* to still work -- well, sort of -- but the speaker started making similar such noises and I instinctively focused on that aspect of the problem. After coming up at a loss, I pulled the speaker out and put it in a separate box and powered up from a different amp -- voila! The speaker proved to be perfectly fine. The problem was the amp.

If OP either: did not have a load on amp output, or, used instrument cable (low current, high impedance etc vs high current, low impedance, etc) that might be enough to cause damage to the amp.. depending on that and other factors..

I think there may be problem with guts of amp(s) at this point -- difficult to say, but maybe transformer(s)?

..Just brainstorming.

 

[2after909]

-Haven't blown a speaker ever at age 49
-Have now blown 4
-Recently had three main amps serviced

I just have to assume you don't have much experience with random troubleshooting to have got to two blown speakers and not just assumed it is an issue with the work that was done, then to get to four and still be asking what it might be.

One tip for the future that I used often at my work where unusual events could happen due to all the different dynamics happening in the complex facilities I ran. I tried to train staff to always think this way as it is so simple;
When something is happening for the first time, ask yourself..... what are we doing differently for the first time? Or..... what have we recently changed?

The key is the simple acknowledgment that you may have no idea; that you can't possibly see a connection at first glance. But trust the statement and pursue it and you will find it.

Reminds me a bit of when my power supply(PSU) blew on my PC. I replaced the PSU and then found two of four hard drives fried. So I replaced a hard drive, and it fried. So I replaced that one and it fried. At that point I realized I should stop doing that. It turns out some of the SATA connecting ports got whacked when the PSU fried, and I had to replace the motherboard.

The primary problem was my inability to competently troubleshoot the motherboard electronics instead of just swapping another part in.

Back to your issue; it is an issue with the work that was done.

Thanks everyone for your input.

Please know I didn’t blow a speaker and say, “Gee, I’ll try another speaker. Oh, blew that one, too. I guess I’ll try another one, and another one…”

To be clear, after having speaker outs installed in the two combo amps I tried each “head” with a variety of cabinets. I was just trying out my options for matching heads with cabs for recording. It took a couple of sessions, because I have a full time job and two kids and a busy schedule. But I was able to steal a half hour here and there and tried all the options. After doing that I realized that there were little crackly, rattling, splatty sounds coming from the speakers. The damage was done by the time I even noticed it.

And no. I don’t have any experience troubleshooting. My only previous experience was with the amps I’ve owned and used - a super reverb, a twin, a bassman, a silvertone twin twelve, and a blues jr. Literally all of them just worked. I never had to troubleshoot anything. I never had issues with my gibson amp or the old Ampro either. Even the epi valve jr only ever needed a tube replaced. I guess I’ve just had good luck? I don’t know. Anyway, whenever I did have a little amp issue I just took it to a tech and he fixed it for me.

At any rate, I spoke to my current amp tech. He’s coming over next week, after my holiday travels, with some gear and tools to check out the amps and figure out what’s going on with them. I’ll gladly report back as to the resolution of this problem.

Thanks again, everyone.

 

[2after909]

@2after909 , as you'll know, longer threads start recirculating. Suggestions, questions, and (sorry) criticisms start to come around over and over, like logs in a whirlpool. People are busy. Reading threads takes time.

One thing that may end the cycle (for respondents who read *any* post before theirs) is when the OP takes some definitive action. "I've decided to use my amps as lawn ornaments" or "I took up Zoroastrianism" or "I'm taking my amps and speakers for a checkup."

Thanks. Yeah, I’m getting it all checked out.

 

[JustABluesGuy]

Thanks everyone for your input.

Please know I didn’t blow a speaker and say, “Gee, I’ll try another speaker. Oh, blew that one, too. I guess I’ll try another one, and another one…”

To be clear, after having speaker outs installed in the two combo amps I tried each “head” with a variety of cabinets. I was just trying out my options for matching heads with cabs for recording. It took a couple of sessions, because I have a full time job and two kids and a busy schedule. But I was able to steal a half hour here and there and tried all the options. After doing that I realized that there were little crackly, rattling, splatty sounds coming from the speakers. The damage was done by the time I even noticed it.

And no. I don’t have any experience troubleshooting. My only previous experience was with the amps I’ve owned and used - a super reverb, a twin, a bassman, a silvertone twin twelve, and a blues jr. Literally all of them just worked. I never had to troubleshoot anything. I never had issues with my gibson amp or the old Ampro either. Even the epi valve jr only ever needed a tube replaced. I guess I’ve just had good luck? I don’t know. Anyway, whenever I did have a little amp issue I just took it to a tech and he fixed it for me.

At any rate, I spoke to my current amp tech. He’s coming over next week, after my holiday travels, with some gear and tools to check out the amps and figure out what’s going on with them. I’ll gladly report back as to the resolution of this problem.

Thanks again, everyone.

Good luck with it.