Bass cab problem

Rigsby

Hi guys !

Maybe you can give me some advice or opinions. I have an Ashdown ABM 500 2x10 combo (min load 4 ohms ). I recently bought an Ashdown ABM mini compact cab 1 x 15 as an extension ( 8 ohms 300w ). On the low bassey notes there is a bad buzzing sound. If I roll off the bass it's fine, yet the 2x10's seem to be able to handle it ok. Even with the bass eq'd flat I get this sound if I pluck a bit hard. I'm assuming the speaker is ok, just that it cant handle too much bass. Could it be because the cab itself is too small to handle too much bass ?

This link shows the cab I have ;

http://www.soundslive.co.uk/product~name~Ashdown---ABM-MINI-15~ID~1452.asp


EDIT : Meant to say, I took out the speaker to see if there was anything visible that could cause the problem. Found nothing obvious.

Doctor J

I have the ABM 115 compact cab and it's plenty big to belt out the low end at volume. I use mine for five string work all the way down to dropped A and I've never had buzzing or noise from it in over five years of abuse, that includes countless rehearsals, getting chucked into the boot of the car and no PA-assistance gigs.

Mini cabs are in vogue right now (check out Markbass for example), you'll experience less low end from a small cab but the design doesn't induce buzzing.

What you're experiencing sounds like a speaker issue to me, unfortunately. Try tightening the screws which hold the speaker into the cab but I wouldn't be too optimistic it will work.

gotBass

couple of other thoughts:
1. does the noise continue if the cab and amp are side by side?
2. is the lead ok? possible bad grounding?
3. is the output jack from the amp ok?

Other than that I'm in agreement with doc J, bad speaker or wiring to the speaker. I have one of those myself and it has been trouble free for 3 years now.

does this happen at full power or what volume level?

Doctor J wrote: »

I have the ABM 115 compact cab and it's plenty big to belt out the low end at volume. I use mine for five string work all the way down to dropped A and I've never had buzzing or noise from it in over five years of abuse, that includes countless rehearsals, getting chucked into the boot of the car and no PA-assistance gigs.

Mini cabs are in vogue right now (check out Markbass for example), you'll experience less low end from a small cab but the design doesn't induce buzzing.

What you're experiencing sounds like a speaker issue to me, unfortunately. Try tightening the screws which hold the speaker into the cab but I wouldn't be too optimistic it will work.

Rigsby

Thanks for the replies lads.

Doctor J : Yes, I tightened everything, though it really did n't need it. From what you say, it should be able to handle reasonable low end.


gotBass : Only got a new speaker cable yesterday. Generally it's ok at near full volume provided the bass is rolled off a good bit. Low "E" is ok, but E flat played on the E string is not. Will try speakers side by side later.

I have another combo in the band's rehearsal room. I'll bring it along next time and try it on that.

Thanks again.

gotBass

Ok so,
500W amp at 4 Ohms

you have a 250W rating at 8Ohm in parallel with the speakers in the combo which are more than likely rated at 250wrms +.
it is unclear whether the 1x15 is 250rms or peak power, but by all indications it's a peak value. so the 1x15 is farting before the 2x10.

it's still a hell of a volume.

I use the abm300 head and abm2x10h with the mag115.
So I've never driven my cab that hard. at full volume you are pushing an extra 200W into the cabs more than me roughly.

so I suspect that you just need to turn down.

and buy ear plugs ;-)

check with ashdown if the 250watt rating is RMS or peak and that should answer your question

Rigsby wrote: »

Thanks for the replies lads.

Doctor J : Yes, I tightened everything, though it really did n't need it. From what you say, it should be able to handle reasonable low end.


gotBass : Only got a new speaker cable yesterday. Generally it's ok at near full volume provided the bass is rolled off a good bit. Low "E" is ok, but E flat played on the E string is not. Will try speakers side by side later.

I have another combo in the band's rehearsal room. I'll bring it along next time and try it on that.

Thanks again.

Rigsby

Thanks for that gotBass ! Tried it again this morning. It did n't seem quite as bad as last time. It also seemed intermittent. Took the speaker out and had a close look. There was nothing obvious. Replaced everything and tried again. Seems OK now.

You are right, I may have been pushing it too hard while trying it out. I have not used it with the band yet. I would n't normally have it that loud. Fingers crossed that the problem has been inadvertently solved.



BTW, thanks for the tip, but I always use ear plugs. See the "Ear Protection" thread.

Eoin Madsen

Check the screws and fittings throughout the cab, incl handles etc. I've had problems with low end causing things to rattle a few times. Also try it in a different room, if you haven't already. Just to rule out those things.

Rigsby

Eoin Madsen wrote: »

Also try it in a different room, if you haven't already.

Funny you should say that. This morning when I tried it again it was in a much bigger area, and it did n't sound quite as bad as previously.

basshead56

Hi,
Sounds to me that what your problem here is an impedance mismatch.
You have a 4ohm min load amp and an 8ohm ext cab. that combined impedance works out at around 2.6 ohms- which means ur amp is not suited for use with ohm cabinets- what you need to make that speaker rig work is an amp with a 2 ohm min load.
Now even at 2.7 with a 2ohm min load, most amp manufacturers will state that they do not recommend using this type of set up-Ampeg, Fender/SWR, Mesa Boogie etc.
I had a similar problem using a 4ohm Ampeg 4x10 and an Ampeg 1x15 at 8ohms with an SVT 350. I switched to amp with a 20hm min load- Fender 400 Pro head-and the problm was solved.
The other (cheaper) way to solve ths problem is to use a cab with a lower impedance level (4ohms).
Hope that helps

Parsley

basshead56 wrote: »

The other (cheaper) way to solve ths problem is to use a cab with a lower impedance level (4ohms).

If you're right about the cause, two 8 ohm cabs would work just as well.

:edit: and I don't think you are right, on re-reading the OP. He had the combo, which I'm pretty sure is loaded with an 8 ohm cab, and he got a second 8 ohm cab, giving a toal load of 4 ohms.

Rigsby

Parsley wrote: »

:edit: and I don't think you are right, on re-reading the OP. He had the combo, which I'm pretty sure is loaded with an 8 ohm cab, and he got a second 8 ohm cab, giving a toal load of 4 ohms.

That is correct. I got the 8 ohm cab to go with the combo which is also rated at 8 ohms. I'm not an expert on this, but by my reckoning that should give me 4 ohms.

unclebill98

Hi Rigsby, you are correct in what your doing. You've got a 8ohm combo and a 8ohms extension cab, bringing the load to 4ohms. Its a standard setup and your correct with your matching of cabs.

basshead56 thinks the combo is running at 4ohms already, which is not the case. 4ohms is the min load allowed.

Rigsby

unclebill98 wrote: »

Hi Rigsby, you are correct in what your doing. You've got a 8ohm combo and a 8ohms extension cab, bringing the load to 4ohms. Its a standard setup and your correct with your matching of cabs.

Thanks for clearing that up unclebill98. I did some research before buying the cab and was fairly sure I was correct. Nice to have it verified all the same.


Anyway (fingers crossed) it seems to be ok now. I may have been pushing it too hard when trying it out.

Patricide

By any chance do you have an input section on your amp with a level knob?

If you do turn that down or else try putting the bass into the active input. Used to happen to me with my old ashdown mag head untill i figured out it was excess gain and i leanred what the vu metre was for.

Rigsby

Patricide wrote: »

By any chance do you have an input section on your amp with a level knob?

If you do turn that down or else try putting the bass into the active input. Used to happen to me with my old ashdown mag head untill i figured out it was excess gain and i leanred what the vu metre was for.

You are right. When I was trying out the new cab, I think I might have had the input level too high.

As for the active input, didn't think it would make a difference. I'll give it a try though.
Thanks.