Damaged amp by plugging a bass in?

[Alex_SG]

I'm currently heading out to the guitar shop with my son and his amp. He said it's not sounding right after plugging his bass into it... It's a 40w Blackstar (transistor, not tube.)... I personally can't work out how plugging a bass in would damage it, but what do you do?
It's one of these: Blackstar ID:Core V3 Stereo 40 review

 

[Amp Mad Scientist]

I'm currently heading out to the guitar shop with my son and his amp. He said it's not sounding right after plugging his bass into it... It's a 40w Blackstar (transistor, not tube.)... I personally can't work out how plugging a bass in would damage it, but what do you do?

Sometimes it cooks the speaker from low frequency but usually it doesn't matter.
There's really no reason why a bass would damage it.
Maybe it did overload the speaker.

 

[iblive]

Sometimes it cooks the speaker from low frequency but usually it doesn't matter.
There's really no reason why a bass would damage it.
Maybe it did overload the speaker.

I have plugged my bass into my 20w Traynor. But I was always careful not to crank volume up too high…… just in case. Back of my mind didn’t want to blow the speaker.

 

[Amp Mad Scientist]

I have plugged my bass into my 20w Traynor. But I was always careful not to crank volume up too high…… just in case. Back of my mind didn’t want to blow the speaker.

The speakers in small amps (these days) are very minimal.
I tell people to use a speaker that is 2X the power of the amplifier, or more.
This is what Dan Armstrong recommended for reliability.

 

[iblive]

My Traynor is a YGM3 from 1974. No idea what the wattage rating was on the original Marsland speaker, but it’s been replaced with a Celestion V30. If I remember right. It’s rated @ 60w.

But for me it’s a moot point. Babysitting my kids 400w bass amp with a 4-10”s cabinet. If I feel the need to make the house shake, I plug into it.

 

[Thatbastarddon]

I gave an opinion in the other thread…sorry, I didn’t see this one first.
@Amp Mad Scientist sorta hits it on the power spec thing. Bass amps are often putting out a lot more power than guitar amps because it takes that kind of power to produce useful levels of the required frequency content. If you try to push a guitar amp speaker that hard( to produce bass frequencies at levels that are considered desirable for practice volume and above) speakers can be damaged. But please read my other reply, in the other thread.

 

[67plexi]

The blackstar x 2 6.5" speakers 20 watts what kind of watts peek my guess

 

[rolandson]

It maybe be said up stream, for which I apologize in advance and am happy provide corroboration...

It's not watts or efficiency...it's impedance.

Amp transformers are particular about the load (impedance) they "see" from the speaker, which varies with the frequency it's being called upon to reproduce. Higher the frequency the greater the impedance, lower frequency...you get the picture.

A bass is capable of notes that drop the load to a point that most guitar amps are not designed to handle, effectively cooking them.

My bet, the transformer is toast.

 

[Alex_SG]

Thanks for the replies, guys. It's come out with a clean bill of health. The tech seems to think it overheated, as my son had everything clocked out to 11, and shut down as a self preservation thing.
It's working as it should now, after resting overnight.

 

[rolandson]

Thanks for the replies, guys. It's come out with a clean bill of health. The tech seems to think it overheated, as my son had everything clocked out to 11, and shut down as a self preservation thing.
It's working as it should now, after resting overnight.

Tell your son he's fortunate ...
And then get him a copy of Donald Brosnac's The Amp Book, A Guitarist's Introductory Guide...

The amp book : an introductory guide to tube amplifiers : Brosnac, Donald, 1947- : Free Download, Borrow, and Streaming : Internet Archive

Includes index

archive.org

Pretty sure it's on Amazon ...

It's written for the non-electronics type who wants, or would benefit from a grounding in the basics...explains pretty much everything without a bunch of tech speak. While tube appears in the title, its information is applicable across platforms

Once read, he'll never ever do that again.

 

[Amp Mad Scientist]

It maybe be said up stream, for which I apologize in advance and am happy provide corroboration...

It's not watts or efficiency...it's impedance.

Amp transformers are particular about the load (impedance) they "see" from the speaker, which varies with the frequency it's being called upon to reproduce. Higher the frequency the greater the impedance, lower frequency...you get the picture.

A bass is capable of notes that drop the load to a point that most guitar amps are not designed to handle, effectively cooking them.

My bet, the transformer is toast.

That is an astute observation.
Point well taken.

I put thermal cutoff switches in amplifiers that are modified.
This may upset people who think that the amp should keep playing, even when it's being heavily abused....
They ignore speaker impedance, they block off the cooling vents...
and their going to get pissed when the amp shuts itself off.

I am obligated to make a modified amplifier safe; I have to be conscientious about fire safety.
(most people despise safety and actively work against it)

 

[dirocyn]

Thanks for the replies, guys. It's come out with a clean bill of health. The tech seems to think it overheated, as my son had everything clocked out to 11, and shut down as a self preservation thing.
It's working as it should now, after resting overnight.

Bass needs big power to sound loud. 5x the power of the guitar, is the rule of thumb. I always found I needed about 300w for the bass to sound as loud as a 50w amp. Add on top of that, most guitar speakers have really poor efficiency below 100hz. If you're trying to play bass through a guitar amp it's super tempting to turn up, and up... because it doesn't seem loud enough. And amps & speakers designed for guitar can't handle that. If you turn everything to 11 something is going to break.

If you plug a guitar into a bass amp and turn everything to 11, the thing that breaks will be your ears. Even if it's a "little " bass amp like a 75w Bassman.

 

[iblive]

Thanks for the replies, guys. It's come out with a clean bill of health. The tech seems to think it overheated, as my son had everything clocked out to 11, and shut down as a self preservation thing.
It's working as it should now, after resting overnight.

Brings back memories from a lifetime ago. As in a punk teenager. Playing a 45….. remember those? Playing it on my mom and dad’s console tv stereo. Status Quo “Pictures of Matchstick Men”. Home alone. Had volume cranked. Sounding great. Stereo shut itself off. After the initial…. Oh crap, I blew up the stereo…. I realized what had happen. Then it was hilarious. Never told them.

 

[Scott Baxendale]

I'm currently heading out to the guitar shop with my son and his amp. He said it's not sounding right after plugging his bass into it... It's a 40w Blackstar (transistor, not tube.)... I personally can't work out how plugging a bass in would damage it, but what do you do?
It's one of these: Blackstar ID:Core V3 Stereo 40 review

Maybe he blew the speaker?

 

[Amp Mad Scientist]

Maybe he blew the speaker?

When technicians test amplifiers they normally ignore the speakers entirely.

 

[Thatbastarddon]

Speaker(s), or output transistor overheat, are my personal guesses…but hey, I just tinker with my own gear, when I have to.

 

[Alex_SG]

According to the tech, he probably overheated it. It's back to normal now. I've told my son not to play with it cranked to 11, but to use the gain and tone knobs instead.
Thanks for the input guys!