Help with Speaker Replacement

[JonnyAngle]

I have a GK Backline 210 Combo. When I hit the low notes I get a really annoying rattle, so I figure the speakers must be blown. I look up in the manual (Linked below) that I have 2 10 inch 8 ohm speakers. I hook up my mulitmeter and find that I actually have 2 10 inch 19.4 Ohm Speakers! Does this difference in resistance mean they are blown?

Assuming that they are blown....

Any recommendations for a better quality speaker?

Manual:
http://www.gallien-krueger.com/manuals/Backline350.pdf

[Rick Auricchio]

Your multimeter will measure DC resistance, which is not the same as impedance. It's somewhat close, but not exact.

Your speakers are apparently 16-ohm units, wired in parallel, which results in an eight-ohm cabinet.

1. Are you sure they're the original speakers?

2. Check the cab carefully for any loose hardware or air leaks. Tighten the speaker mounting bolts (carefully!) to ensure they're tightly mounted without air leaks.

EDIT: The manual claims the 210 combo is running at four ohms, which implies there should be two eight-ohm speakers. I suspect they aren't the original speakers, or the manual is wrong.

As for replacements, a cab is designed to match the speakers. The best replacement is the original. If you want to use a different speaker, then its specs should be very close to the original. Unfortunately, amp manufacturers don't publish their speaker specs.

[JonnyAngle]

What I think I am finding out is that there are 2 10 inch speakers creating a 8 Ohm LOAD. I bought the unit from a reputable store, so I'm confident they are original speakers. Plus, I have a matching 4x10 cabinet and they look the same. The 4x10 is an 8 Ohm load so both cabinets make a 4 Ohm load.

I'll re-install the speakers and tighten them up a bit. I know these are "not the best speakers," so what would be a step up?

Side note: The 4x10 sounds much better with very little rattle compared to the 2x10.

[Rick Auricchio]

OK, this makes sense. And you might see GK markings on the speakers, indicating they're originals.

Installing non-original speakers would require careful measurement of the cabinet interior dimensions and port size, then running computer simulations using new speaker specs. You may have seen mention of WinISD, which is the modeling program.

You still might not find any replacements that are "better" than the originals. WinISD, when properly used, will predict the max SPL (loudness) you'd get, and the max power that you can run before the speaker farts out. Most of the performance depends on the cab size and porting, which are not going to change.

Since your 410 also rattles, are you sure it isn't something else in the room rattling? Also check for air leaks in unused input jacks on the cabinet. Eden cabs leak through the 1/4" jacks, and it sounds like a rattle/buzz/blown speaker! Plug 'em with foam earplugs.

[JonnyAngle]

hmmm... I'll see what happens after I re seal everything.

[Rick Auricchio]

If you have an audio oscillator (or a computer program to do this), you can run a 25Hz sine wave through the amp. This tone is almost inaudible, but it will pump nicely to find air leaks.

Set the amp loud enough to get about 1/4" of cone movement; it won't SOUND very loud, but that's plenty. Then listen closely around the speakers, at cabinet seams, near the jacks for air leaks. You can easily hear the wind noise through a leak.

Parts Express (partsexpress.com) makes speaker gasket tape. Use it if the speaker frame doesn't seal tightly to the cabinet.

[BassmanPaul]

If you are using a 2x10 at 8Ω and a 4x10 at 8Ω, the 2x10 is receiving the same power as the 4x10. You'll keep on having trouble with the 2x10s.

Paul

[JonnyAngle]

Originally Posted by BassmanPaul

If you are using a 2x10 at 8Ω and a 4x10 at 8Ω, the 2x10 is receiving the same power as the 4x10. You'll keep on having trouble with the 2x10s.

Paul

That is the scenario I am having. Why is that causing problems?

[billfitzmaurice]

Originally Posted by JonnyAngle

That is the scenario I am having. Why is that causing problems?

He told you, the 210 and 410 have the same load, so twice the power is going into each driver of the 210 than those of the 410. Running a 210 and 410 together the 410 should have half the impedance of the 210 for equal power distribution to all six drivers.

[RickenBoogie]

Because the exact amount of wattage is sent to both cabs. The 4x handles it with ease, the 2x has to work harder to keep up with it. A better match for a 210 combo is either another 210, or a 1x15.

[JonnyAngle]

Dang.