Acoustic 215BX/406 cabinet driver question

[gaberamach]

Hello everyone.

I have a 2x15 acoustic 215BX cabinet (same dimensions as the 406 afaik) that I recently got only to find out that the drivers need replaced.

Will Celestion Pulse15 400W speakers work with the cabinet’s stock port design? I am planning on running a 1978 Bassman 135 head. I will also likely run OD or fuzz pedals, but with the wattage of these speakers, I’m not really worried about wattage as much as if they will function well in this cabinet.

I’ve read mixed opinions around the web and I’m wondering if these speakers can perform optimally in this cabinet and not “fart out”

 

[agedhorse]

Yes, it's a good drop-in match, but just note that mechanically the 215 will be mechanically limited to about 400 watts RMS.

 

[gaberamach]

Yes, it's a good drop-in match, but just note that mechanically the 215 will be mechanically limited to about 400 watts RMS.

Do you mean in terms of a 400 watt amp? Or speakers. Because the speakers are 400w each… just checking

 

[agedhorse]

Mechanically in this box, each speaker is good for about 200 watts RMS regardless of what the marketing power might say.

 

[gaberamach]

Mechanically in this box, each speaker is good for about 200 watts RMS regardless of what the marketing power might say.

Is this due to the porting system? Shouldn’t be an issue for me but wondering if I ever wanted to use it for higher power application could you theoretically add another port or two (obviously doing the math to make sure it works)

 

[agedhorse]

Is this due to the porting system? Shouldn’t be an issue for me but wondering if I ever wanted to use it for higher power application could you theoretically add another port or two (obviously doing the math to make sure it works)

No, it's the mechanical limitations of the driver in that box. Tuning changes might improve things A LITTLE, but not but much. It's a large box with good extension but the trade-off is that you lose mechanical power handling.

This is why it's not as simple as it appears.

 

[gaberamach]

got the new speakers loaded up today. Sounds awesome. Super loud and tons of low end. However, I’m noticing distortion and I’m not sure if it’s the amp or the cabinet.

What kind of volume levels on the knob should I expect from this amp before I see some breakup? For reference I’m running the EQ on the normal channel - deep switch on, volume 3, bass & mid at 10. Is it normal for the amp to be breaking up at this level with the master volume turned up? I have little experience with the UL fenders… not sure maybe it’s ridiculous to run the EQ that way.

Too much low end overwhelming the speakers? Or is something up with my amp? I was under the impression that the UL fenders are completely clean until like 6 or 7, but I understand with bass (especially playing as low as drop c#) it could be different.

The actual volume levels of the amp seem to be more than adequate but I notice it gets to basically gig volume levels at like 2 and then it starts breaking up not long after that. Idk… maybe that’s just how these amps behave? Or am I pushing too much low end for a vintage cab…

 

[Aidenn7]

that fender amp is tube. so you notice a flubby low end distortion. so a highpass is a good idea. also a good idea to have the amp checked if it continues. or check the bracing and damping of the cab

 

[J Wilson]

You'll have to start testing your way out of this.

First off, DEEP turned on, and maxing the BASS and MID controls would be the first suspects I questioned. That's pushing a LOT of deep end, the hardest thing for amps and cabinets to do well if approached incorrectly. Turn the DEEP off, slide the other two back to 5 instead of 10, turn it up to where it was distorting and see what you hear. That could be it. Do this with NO effects inline.

After that, the rest of the usual suspects, cables, a different amp, etc. Eventually, you'll get a confession out of the right suspect.

 

[agedhorse]

The Bassman 135 head, when drive hard, will sound like you describe. When this happens depends on the bass, your choice of eq and the overall volume.

 

[Stylee Mousse]

Yep, roll off the lows and get more clean volume. There is a finite amount on tap with the head.

I ran 215 Sunn cabs with 200, 300, and 100 watts. All worked well for me in loud bands. The last (vintage V-4b ) is still in play. That takes the most finesse to stay clean(ish).

 

[gaberamach]

I have found that part of the distortion is definitely due to the deep switch and low end control. I got a good bit more clean volume that way. I assume being 135 watts… maybe the “super duper clean” thing is more for guitar.

Also noticed that the bottom speaker in rattles when I play an A. The rattling stops if I press my hand against the metal edge of the speaker to the baffle, so it’s certainly a mounting thing. The cabinet only has 4 metal plates that go over the speaker to clamp it to the baffle. Should I mount the speaker differently to prevent this? The top speaker doesn’t seem to do it.

 

[agedhorse]

Is there a thin cardboard or foam gasket between the back flange of the speaker and the baffle?

 

[gaberamach]

Is there a thin cardboard or foam gasket between the back flange of the speaker and the baffle?

No there is not.

 

[agedhorse]

There should be a thin cardboard/foam gasket, I think that’s the root of your issue. The gasket helps take up gaps, especially if the baffle isn’t perfectly flat.