Too much power blew speaker?

  • Thread starter Thread starter RideTheCrash
  • Start date Start date
RideTheCrash

RideTheCrash

Member
I posted a few weeks ago about my bass amp (Sonax 550-B from '73, nothing special). I got it back from somebody who had it for about 6 months because my brother left it down there at a practice and it's difficult to make a trip down there.

Anyway, when I turned on the amp it would make a large HONK noise which really moved the speaker (15"). And it hummed really badly, and everything sounded like farting or bad vibrato. It was suggested that it could be bad caps or connections, but I think it could be the speaker itself now. I know it looks fine, but I'm thinking maybe the coil inside is ripped.

It doesn't sound quite as bad, but similiar to when I put the current speaker in and the one before it was visually ripped to shreds. A friend of mine has a brother who is very knowledgable about speakers and told me over the phone to do the battery test with the speaker terminals. I got no movement at all. Though when I do disconnect the speaker and turn on the amp, the insides of the amp buzz a bit, I don't know if that's normal.

So if the speaker is messed up, which is likely, it's either two causes:

1) Somebody played the living hell out of this thing. Not likely...I know it was at some guy's house for months, but my brother said it started acting up when they got down there in the first place. Plus the other guy never touched it (when you're rich, you don't need to play some stranger's amp).

2) The music store sold me the wrong kind of the speaker for the amp, and my amp killed it over time. This is where you guys come in, because I know jack about this stuff. The speaker is rated at 8 ohms, but I don't know what the amp expects, because it doesn't say but I'll e-mail Yorkville and see if they know. The amp is just a combo amp (with a ridiculously large cabinet) with a 15" speaker.

I brought the amp in a year and a half ago to the music shop, but the guys never looked at it, they just knew I needed a 15" bass speaker and they gave me the Eminence one I have now. Is it possible I got the wrong rating for the amp and my amp killed it? The amp is only 50 watts.

Thanks guys.
 
Speaker Ohms must match the amps output ohms or you could either smoke the speaker,... or the output transformer in the amp,.... if the amp is 8 ohm output,.... you can safely use either an 8 ohm speaker,... or a 16 ohm with no ill effects,... however,.... if the amps output is 16 ohm, and you use an 8 ohm speaker, you risk overheating the output transformer,... and even burning it right up,......

In which case, you could also damage other parts of the amp.....
 
First thing is 50 watts isnt shit for a bass amp. Second loaning your shit out to someone else even a brother is asking for trouble. Third It got left some place where other people could have messed with it and over driven the amp to hard. I have seen alot of bass speakers blown cause of small power like the one in your amp. If anything it was the lack of power and abuse that blew your speaker and not high power.
Take the loss and I wouldnt try and push the problem off on the store that sold you the speaker. Go buy a new speaker and concider it a lesson learned.
 
I never said 50 watts was "shit". I loaned it out expecting it back the same day. The fact that it was fucked the moment my brother used it means it wasn't abused by the guy. It apparently just sat there for months. I'm not trying to push the problem off on the store, but I'm saying maybe they sold me the wrong speaker, because they never bothered to even look at the amp and say 'alright, well...'.

Shit happens, no kidding.

I'll e-mail Yorkville and see if they can tell me the output ohms.

I'm not stupid either by the way, thanks.
 
What he meant was: the lack of power might have blown the speaker.

Why don't you plug the amp into a different speaker to find out if it is the amp that's broken or the speaker.

It might be safer to plug the speaker into something else that you know works to see if it's blown. If the speaker works, then the amp is messed up.


BTW, if it is a solid state amp, anything above 4 ohms should be good.
 
Oh, okay. The amp is solid state, I checked the schematics I got in PDF form, and I couldn't find anything that mentioned output ohms, so I'm still waiting for my e-mail.

I was thinking of plugging the amp into a new speaker, but I wasn't sure if I'd blow the speaker up. All I have in my house is a small Crate practice amp and a small Fender Frontman bass amp, which speakers are like 8"-10" tops. If I have my friend's brother check it out, he might be able to bring a 15" speaker to test it out though. And what about the battery thing I tried?

So how does lack of power blow the speaker? Just out of curosity. And I assume it takes time because it took a year for it to happen.

Thanks.
 
RideTheCrash said:
So how does lack of power blow the speaker? Just out of curosity. And I assume it takes time because it took a year for it to happen.

Thanks.
Click to expand...

The idea is that driving the amp into heavy clipping raises the average power output of the amp, like you use compression to raise the average volume of a track. If the speaker cannot handle the higher average power level, it will burn up.

So the speaker still gets fried from too much power, paradoxically from being driven by an amp with not enough power. A higher powered amp can deliver enough clean power to handle the peaks, without being driven into clipping.

That being said, this scenario is fairly unlikely in a bass or guitar rig unless it is used fairly hard. Especially an old solid-state rig, which would sound very bad if clipped. You would notice right away if you were clipping it.

Solid-state amps of that vintage are pretty likely to have some issues. I'd say it's the amp causing the problem.


When you did the battery test, you just connected the terminals momentarily, right? For a fraction of a second?
 
If you try to play a low wattage amp especialy a bass amp at high volume levels it will clip the amp and put out distortion which will also produce heat on the voice coil of your speaker And melt the voice coil. It was a common problem with older bass amps when everyone started playing rock n roll at high volumes. Until the power went up in the amps speakers got blown all the time. Also alot of amps these day have compression built in to help protect the speaker from these problems.
 
Uhh, we put the battery to the terminal for a few seconds probably. Why? Did I destroy it even more?

Yeah I guess since the amp is 33 years old, it's going to be prone to this. I didn't use it a whole lot, mostly when I'd jam in the summer and the bassist would use it instead of hauling a halfstack over. But I never noticed any sort of clipping or distortion when it was used. I try to take as best care of my equipment as possible.

But yeah, maybe it is the amp. Is it normal for the amp to buzz when the speaker is disconnected, nothing is plugged in and all knobs are down? Probably not. The buzz is faint but if you put your ear to where all the guts are, you can hear it.

The one thing I never got answered was when I put in the speaker I have now, it produced an airy sound. Not a hum or buzz, but air. When I accidently unscrewed the screw holding the grounding wire and then got it fixed, I believe it got a tad louder.
 
Herm said:
If you try to play a low wattage amp especialy a bass amp at high volume levels it will clip the amp and put out distortion which will also produce heat on the voice coil of your speaker And melt the voice coil. It was a common problem with older bass amps when everyone started playing rock n roll at high volumes. Until the power went up in the amps speakers got blown all the time. Also alot of amps these day have compression built in to help protect the speaker from these problems.
Click to expand...

Distortion doesn't kill speakers. Just ask Jim Marshall or the guys at Mesa/Boogie. That whole "distortion kills speakers" thing is a myth. What kills them is not being able to handle the increased average power that results from compression due to clipping.

Compression and limiting can protect against damage from peaks, and compression of course is a great tone-shaper. They have the sometimes unrecognized danger of raising average levels, sometimes to the point where damage can occur. As always, the only way to really protect your speakers is through knowledge and common sense.
 
RideTheCrash said:
I was thinking of plugging the amp into a new speaker, but I wasn't sure if I'd blow the speaker up.Thanks.
Click to expand...
Plug a different amp into the speaker, see if the speaker is good.
 
Alright I hooked up the speaker to my brother's small Frontman amp. It was difficult because it was a closed back and I had to open it up and sit the speaker (with help of course) close enough so the speaker wires went far enough. Then we had to do a really quick test because of the electrical plug.

I plugged in a guitar and played a power chord, because that caused worse sounds than other chords, and I got a normal clean sound. So it must in fact be the amp. Which kind of makes me relieved. Thanks guys. I'm still going to double check that ohms thing in here once I get the e-mail though, just to be safe.
 
Okay, here is Yorkville's response:

"Hi there. Unfortunately the Sonax 550B was discontinued around 30 years ago and our records are lacking in certain details. The old brochure states that it put out 40 Watts, but doesn't specify into what speaker load. In any case you can be confident that the maximum sine-wave output would not exceed 40 Watts into 8 Ohms. Ideally bass guitar speakers should be able to handle around twice the amplifier's output so you would be looking for an 80-Watt bass guitar speaker.
Thank you for your enquiry."
 
You have determined that the amp is broken. Keep the speaker, throw away the amp.
 
Nah, I'll fix it. Don't have any use for a 15" speaker otherwise.
 
RideTheCrash said:
Nah, I'll fix it. Don't have any use for a 15" speaker otherwise.
Click to expand...
Knowing you, you will soon find another forgotten piece of musical equipment history that needs the 15.
 
You make it sound like I'm loaded with old gear. I have the old mixer and this amp. Which I got for free anyway.

I don't see why you have to be such an asshole about it everytime.
 
You must log in or register to reply here.
Back
Top