Moog Music Forum

i use the self oscillating sinewave theremin deal on the Low Pass filter quite a bit, and have since put my amp in the shop twice, and had 2 different amps cut out on me during a gig.

Are these known to damage the amps with super low frequencies?

Any way to avoid this?

Probably - was it the amp or the speaker?

Speaker: Low frequency = slow movement -> burns your speaker coil out.
Amp: Bass requires more energy -> amp overheating/drawing too much power off the transformer.

Any way to avoid this?

Turn the volume down or get a better speaker.

get a bass-amp?

Long story short: Yes, Moogers can and will damage amplifiers. The low pass filter manual even warns of speaker damage if the frequency (any frequency) is left constant for a long period of time. How long is this time? I don't know... just don't do it... If you vary the frequency a little bit you will find amps last longer, because you allow the speaker to 'rest'.

Don't forget that these moogers are loud, much more loud than your guitar, so overpowering a component into destruction is much easier.

Bass frequencies do not draw more power when you are talking about a single speaker system... system to system maybe different (ie stereo vs guitar amp). Bass frequencies are harder to amplify via a loud speaker because a larger cone mass is required to move the amount of air required to make low frequencies more audible, or to what appears to be equivalent in volume. In a single speaker set-up constantly producing 40 watts of power, you can never get 50 watts of power to boost the low end. In a home stereo, you generally have a tweeter, mid range and low end speakers, each with crossovers and possibly amps of their own to create the power required to make the overall sound of all frequencies somewhat equal. Every sub woofer box has its own amp...

The proof to this is: use the self ocillation through a guitar amp, and slowly turn up the frequency from low to high... there will be a point where the frequency seems to get louder, really it does, but only because the speaker is more efficient at producing that "louder" fequency. Also your ears can better translate that frequency and thus feels louder.

Don't forget that playing a note on a guitar compared with a self oscillation is different; guitar notes have all kinds of semi tones (frequencies), and fade in volume over time, but a self oscillation is a single frequency, that you control the volume of.

Alien8 wrote:Bass frequencies do not draw more power when you are talking about a single speaker system... system to system maybe different (ie stereo vs guitar amp). Bass frequencies are harder to amplify via a loud speaker because a larger cone mass is required to move the amount of air required to make low frequencies more audible, or to what appears to be equivalent in volume. In a single speaker set-up constantly producing 40 watts of power, you can never get 50 watts of power to boost the low end. In a home stereo, you generally have a tweeter, mid range and low end speakers, each with crossovers and possibly amps of their own to create the power required to make the overall sound of all frequencies somewhat equal. Every sub woofer box has its own amp...

That's kind of what I meant, but wouldn't moving a speaker more cost more energy?

Alien8 wrote:The proof to this is: use the self ocillation through a guitar amp, and slowly turn up the frequency from low to high... there will be a point where the frequency seems to get louder, really it does, but only because the speaker is more efficient at producing that "louder" fequency. Also your ears can better translate that frequency and thus feels louder.

The "louder" frequency could also be the resonant frequency of the room, or harmonics of the room mode.

Frequency response in most untreated rooms varies by position. Even in treated rooms there is a sweet spot, and you want to keep guitar amps and monitors away from walls and windows, unless you're looking for weird reflections.

YES

I've damaged many speakers with my MF101 and other similar equipment. Both amp speakers and moniters. Very easy to do if you're not careful... even if you are careful.

i dont know what i broke but my amp makes the weirdest noises when i turn it on.

its a fender deville 2x12, you can hear how i use the mf101 self oscillation in my bands song "odie" www.myspace.com/lespecial

as you can see im not leaving it on one frequency for a long time, and im not even pushing it all that hard

man I need to make up a pedal board like that

How about putting a highpass filter between your pedalboard and your amp input?

Or stick a compressor/limiter in your signal chain.

But having listened to the track you pointed out, I'm not convinced that your Moogerfooger did the damage.

Nice music by the way! I used to play around that area 10-15 years ago...

Check some of the basics...

These may seem like silly questions:

Did you check the tubes - both power and drive?

Were both amps devilles?

Have you unplugged the speakers at all to add a cabinet or what not?

Do you trust your repairman / stage crews?

Did you ever have problems before giging?

Start there, it sounds like you have everything under control from the playing aspect (as most guitartist do...) ... maybe the equipment is the culprit (yours or the gig house's)

heironymous, where have you gigged around our area? thanks for listening!

JonnyG wrote:heironymous, where have you gigged around our area? thanks for listening!

Actually, now that I look back at your page, Pearl Street might be the only place. But I used to play around New England, like the Stone Church, the Living Room, the Middle East - and now that I think about it, that was around 15 years ago - scary!

yeah we're playin the stone church this summer