Ampeg 810e making strange noise while playing lowest notes in drop a#

That's a lot of power at such a low frequency for that cabinet imo. I would not be surprised if there was driver damage (possibly to all of the drivers) depending on the amount of good judgement and common sense used. Knob positions mean nothing.

 

Drop A#, so your talking a fundamental of 29hz. I think @ThisBass may have modeled the cab. Maybe he will comment on how much power it can reasonably handle at that frequency.

 

Try the battery test for good measure. All speakers should jump in the same direction when you put 9V across a 1/4 cable.

Dead ones still make sound when played thanks to the working one back pressure.

I see a HPF in your future.

 

Perhaps you might benefit from some help by somebody (a qualified tech) to assist in the troubleshooting to determine what it really wrong?

 

You briefly apply the 9v while watching the speakers. They should all jump outwards with + on the tip of the speaker cable and - on the shaft. It makes a loud WHOMP! Scary loud if you aren't expecting it.

After they jump they hold at the 9vdc position draining your battery until it dies but you remove it just as soon as it goes WHOMP!.

If you catch a glimpse of one not jumping properly the removing of the 9v should be just as obvious as the others settle back to 'zero'. Any that didn't jump in unison that were paired with a working one will jump less vigorously backwards when the 9v is applied as they are pulled in by the vacuum of the other one going outwards.

This tells you very quickly if some are ruined by discontinued voice coil.

Have a look for creased cones. Semicircular traces seen nearer the outer edge.

 

You could try sitting on the cab to determine if it's a bracing issue. Your body weight on the cab will "tighten" up any loose bracing, absorbing your weight. Have a seat and play through the cab.
Fishheadjoe

 

You should try it both upright and laying on it's side to be sure....
Fishheadjoe

 

I just looked at the specs on that cabinet - it says the -3dB point is 58 Hz, and the -10dB point is 40 Hz (essentially Low E on a standard tuned bass). You're asking a lot of that cabinet to go that much lower. My guess is that, whether or not a particular speaker in the cabinet has issues, the amount of excursion you're asking of the thing by pushing it that low is part of the problem, and even if you do "fix" the thing, it won't stay fixed long. Bass guitar cabinets aren't really designed to go that low. A good PA subwoofer (how big is your van?) might do that OK.

I play 4 and 5 string basses (standard tunings on both at this point). I have a couple cabinets that I have used for some relatively low volume gigs - the only gigs I do where an amp is involved are "coffee house" kind of volumes. The cabinets are ones I designed that do better at 40 Hz than standard bass guitar cabinets - they trade off some efficiency and size to do that. I've never played my 5 strings through my cabinets - those are only used on ampless gigs, where the low end is covered by big PA's.

 

The 810E will be fine at low volume. A bass guitar will not put out a lot of fundamental down at 29hz, but if you are really boosting the lows and cranking your amp to max power I think you could easily push your cab beyond it's limits. An HPF would be useful for protecting the speakers.

Here's a related thread on how energy is distributed in the tone of a bass guitar note: Bass frequency/waterfall plots: what they mean to rigs

As far as what people do. I don't think most people actually have rigs that can faithfully play flat to 29hz. They just make due with what they have. Probably the best thing is to learn the limits of you rig and do your best to stay within those limits. If you want speakers that can play high SPL to 29hz you will need a big wallet.

Ported speakers do tend to play lower than sealed speakers. However below their intended pass band, power handling drops off super fast. Basically it's essential to run an HPF just below the tuning frequency of the port to protect the drivers from over excursion.

 

Yes a HPF means high pass filter. Using subtractive EQ down low would offer some protection, but it will not be as effective as an HPF. Also, EQ will probably gut your sound a lot more as well.

If you see a frequency response listed without a qualification like +/- 3dB, it's often the -10dB rating. I don't recommend pushing a ported speaker hard down to it's -10dB limit because the cone will be making massive excursions and not producing much sound. I believe it's fairly common to set the HPF no lower than the -6dB, but it depend upon on the cabs tuning and how hard you intend to push it.

 

The specs on the Hartke boxes are...."sparse" would be the nice word; I'd consider that 30Hz sec to be optimistic (perhaps wildly so) - they don't even give efficiency numbers on their cabinets - they only say they're "really efficient". I wouldn't trust them to do anything without trying it myself, given what I see in the manual.

If you do get your cabinet up and running OK, protecting it is the job of a high pass filter - eq's don't generally do what you want. My guess is that, if you get a high pass filter in place that protects your cabinet sufficiently, you will find the usefulness of your lowest notes is diminished. I personally don't see the musical usefulness of playing a low B on a 5'er in a loud passage if it isn't moving a bunch of air - that's what that note is for at that point. Luckily, I play through some decent PA's. Not sure if that's the situation in your band - if it is, then high pass away, and let the PA carry the load. If not, you might revisit your tuning to something that works better.