Music playback

oppiman · #1 03-26-2011, 05:27 PM

Am I right in guessing that it's NOT a good idea to play music through a bass amp, as it is not designed to handle such frequencies?

44me · #2 03-26-2011, 05:32 PM

No, that's an old wive's tale. Stick with the lessons. I think you'll be more satisfied playing music.

JimmyM · #3 03-26-2011, 05:35 PM

some bass cabs don't have tweeters, and these aren't so good to play music through, and some are voiced more for bass rather than an entire mix and they're not so good to play music through, either. then there are some that sound pretty good to play music through. all depends on the cab.

Robby Hoinsky · #4 03-26-2011, 05:37 PM

you can do it, just how will you be getting the music into the cab might be dangerous for your amp though.

Robby

oppiman · #5 03-26-2011, 06:32 PM

Robby...Is just the input on the amp (which would usually be used to input a guitar signal) a dangerous avenue?
Thanks 44me, I DO play music in a band!

Robby Hoinsky · #6 03-26-2011, 07:29 PM

Quote:

Originally Posted by oppiman

Robby...Is just the input on the amp (which would usually be used to input a guitar signal) a dangerous avenue?
Thanks 44me, I DO play music in a band!

It can be, it is expecting a low level signal, like a bass, but the ipod (or whate have you) will be much higher and could cause some serious overdriving. It can be done, just as long as you keep the volume low on the ipod (or what have you). You'd be safer not to, of course.

Also there is an impedance mismatch, so attempt at your own risk.

Robby

JimmyM · #7 03-26-2011, 09:50 PM

i've run stereo equipment into the input of my amps before and not experienced this problem, robby. can you explain just a little further? not expecting a novel or anything, but it's always worked out for me so i'm just curious what specific problems can arise. i have to reduce a stereo signal to mono to make it work, but it does work.

Robby Hoinsky · #8 03-26-2011, 10:18 PM

Quote:

Originally Posted by JimmyM

i've run stereo equipment into the input of my amps before and not experienced this problem, robby. can you explain just a little further? not expecting a novel or anything, but it's always worked out for me so i'm just curious what specific problems can arise. i have to reduce a stereo signal to mono to make it work, but it does work.

As have I and many other people, but that doesn't make it smart.

The guitar output is a very low signal so the gain on the preamp has a lot of amplification, maybe 30dB or more. The ipod has a much higher signal capable of going straight into a power amp, so when you run it into the preamp of the amp, it is going to boost it even more and potentially send a clipped signal to the power amp section. Will that clipped wave do any damage to the power amp? Maybe, maybe not. Any damage can be avoided by using yours ears. If it sounds bad, it is bad. If it sounds good, it is good.

Robby

JimmyM · #9 03-26-2011, 11:01 PM

ah, so as long as you keep the volume down on your ipod, you should be ok?

will33 · #10 03-26-2011, 11:17 PM

I've had the same experience as far as having a hot signal going in. Keeping the volume low on the source whether ipod, headphone out or whatever tames it down. Little common sense stuff taken from playing the bass through it keeps you from doing damage. Like if you turn the input knob from all the way off up to 1 or 2 and it's already loud as hell, the signal coming in is way too hot. I've burned up some resistors in a CS800 before by running a mic pre into it way too hot. As a result, I learned some stuff and it took 2 days to get that smell out of the room.

44me · #11 03-28-2011, 08:39 AM

Oppiman – sorry, couldn’t resist the snide remark! There’s minimal likelihood of damage to a bass amp sending it higher frequencies than it can reproduce. I’m pretty sure that aggressive slapping is a lot harder on the high frequency driver(s) than typical recorded music. Whether it will sound any good is another story. The output is no longer stereo, and the colored response that many bass amp have is more noticeable on full range material. The issue about overdriving the inputs is a good point, but unrelated to frequency range. If your amp has an active input channel, it will better match the higher signal output from an iPod or other headphone-level output. Impedance mismatch is not a concern. The headphone output is low impedance, the amp input is high impedance. This means the input will negligibly load the source, which is what you want. Other way around is bad.

Ibanez Bassist · #12 03-28-2011, 08:44 AM

I run my ipod through my bass amp all the time at practice when we need to re-visit a song for one reason or another.. the song is not blasting so it can be heard next door but I do play music through them all and have had no problems..

oppiman · #13 03-30-2011, 12:04 AM

Quote:

Originally Posted by 44me

Oppiman – sorry, couldn’t resist the snide remark!

Impedance mismatch is not a concern. The headphone output is low impedance, the amp input is high impedance. This means the input will negligibly load the source, which is what you want. Other way around is bad.

No prob, 44me!! As a matter of fact, check the band out! The Opskamatrists | Facebook

And since I'm new to all the jargon, would you mind explaining what "negligibly loading the source" means?

Thanks!

Oppiman

44me · #14 03-30-2011, 08:55 AM

Only had a second to check it out, but it looks like a fun band!

Both loads (whatever you’re driving – speakers, an amp input, etc) and sources (whatever is doing the driving – amplifier output, pre-amp output, pickup, mic, etc) have impedances. If the load impedance is much higher than the source impedance, we won’t be overloading the source. This is the situation driving speakers from a solid state power amp, or driving a high impedance instrument input from an MP3 player headphone output, or a pre-amp output. When I wrote “negligibly load the source” I just meant that the amp input won’t overload the headphone output (sometimes I forget to ease up on the EE speak - I work with engineers all day).

Things get more complicated with low-level signals, particularly if we want to run them down a decent length cable. This is where we get into impedance matching. There’s a lot of theory and math behind this, but in short, impedance matching is used to ensure that the signal at the far end of the cable accurately resembles the signal at the near end. It also allows the maximum amount of available signal power to be transferred to the input that’s receiving the signal. This helps minimize the amount of electrical noise in low-level signals. In the instrument amplifier / pro audio world, impedance matching is as much about implied signal levels and defined cables, jacks and plugs, as it is about the electrical characteristics of the inputs and outputs.

oppiman · #15 04-01-2011, 11:30 PM

Okay...I think I'm beginning to understand...

If something has high impedance than current flow in it is more restricted, right?

44me · #16 04-04-2011, 09:08 AM

Exactly – so if the load is high impedance, it doesn’t draw very much current. If the source is high impedance, it doesn’t allow much current. If we go back to the often discussed topic of 4 ohm vs. 8 ohm cabs, the 8 ohm cab has twice the impedance of the 4 ohm cab. This means it resists current flow twice as much as the 4 ohm cab, and for a given amplifier output voltage, the 8 ohm cab sees half the current. Power is voltage * current, so with half the current, the 8 ohm cab’s power is half that of the 4 ohm cab. In actuality, you rarely see an exact 2:1 ratio, as the maximum voltage most amplifiers can deliver drops a little as they are loaded more heavily.