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Mesa Boogie Walkabout Part 6

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#50
I remember reading something about it, but please refresh my memory.

Oh...and actually this one is modded for the loop bypass, and it's in bypass. It doesn't cut out, it just farts out on the low notes. If I listen carefully it almost sounds like I can hear the speaker moving around...as in something moving within the area where the magnet is. Now, obviously it's supposed to move, but I've never audibly heard it before.
 
#54
bassgod0dmw said:
Definitely not the preamp tubes. It still does it after I swapped them out. I wish I had another cab right now so I could see if it's the cab or the head, but I'm thinking it's the cab.

Any ideas?
Click to expand...

Could be the speaker surround or spider or voice coil.
Spread your finger tips around the dome on the cone & push in & release a few times. Can you hear the voice coil scrapping on the gap at all? VC may be damaged, or may be touching the gap because the cone suspension isn't holding the cone true on it's excursion on the low notes.
B.
 
#55
bassgod0dmw said:
I remember reading something about it, but please refresh my memory.

Oh...and actually this one is modded for the loop bypass, and it's in bypass. It doesn't cut out, it just farts out on the low notes. If I listen carefully it almost sounds like I can hear the speaker moving around...as in something moving within the area where the magnet is. Now, obviously it's supposed to move, but I've never audibly heard it before.
Click to expand...

Try using the parametric bass to cut 25% or so around 30Hz.

FYI for the next part- I am NOT an expert by any means, just based on reading this article and a few others about the passive radiator design:
HUMAN Speakers: What is a passive radiator?
My understanding is that part of the tradeoff of the passive radiator design is that while the low frequencies right around the tuning of the cabinet are much stronger than a standard designed bass cabinet, the rolloff below it is much steeper than a standard design. Quoting from above article- "An acoustic suspension system also tapers off in its response at only 6 dB per octave. The vented, or passive radiator, system rolls off at 18 dB per octave and thus produce very little usable bass below its resonance - and what it does produce can be rather distorted."

I'm guessing the cab is tuned around 40-50Hz, which is why I don't have the problem with my basses (all tuned to E), but I have a similar issue if I play lower notes with my octave pedal through the Scout cab. It makes sense to me that this might be your problem as well if the distortion only happens on the very low notes (a rubbing voice coil should cause distortion much more often than what you describe).

I've never played through any cabs that could reproduce fundamental notes below E at any decent volume anyway (it is the first harmonic- the 60Hz-80Hz area that I attribute as "bass", not the fundamental notes), but the unique design of the Scout actually audibly rejects them instead of just not reproducing them well! I think you should still be able to get a decent and full sounding response when cutting out some of those fundamental frequencies- I do, but again I don't play a 5 string or go for a very bass-heavy tone.
 
#56
P. Bass said:
Could be the speaker surround or spider or voice coil.
Spread your finger tips around the dome on the cone & push in & release a few times. Can you hear the voice coil scrapping on the gap at all? VC may be damaged, or may be touching the gap because the cone suspension isn't holding the cone true on it's excursion on the low notes.
B.
Click to expand...

It doesn't make a sound or feel weird at all...

sunbeast said:
Try using the parametric bass to cut 25% or so around 30Hz.

FYI for the next part- I am NOT an expert by any means, just based on reading this article and a few others about the passive radiator design:
HUMAN Speakers: What is a passive radiator?
My understanding is that part of the tradeoff of the passive radiator design is that while the low frequencies right around the tuning of the cabinet are much stronger than a standard designed bass cabinet, the rolloff below it is much steeper than a standard design. Quoting from above article- "An acoustic suspension system also tapers off in its response at only 6 dB per octave. The vented, or passive radiator, system rolls off at 18 dB per octave and thus produce very little usable bass below its resonance - and what it does produce can be rather distorted."

I'm guessing the cab is tuned around 40-50Hz, which is why I don't have the problem with my basses (all tuned to E), but I have a similar issue if I play lower notes with my octave pedal through the Scout cab.

I've never played through any cabs that could reproduce fundamental notes below E at any decent volume anyway (it is the first harmonic- the 60Hz-80Hz area that I attribute as "bass", not the fundamental notes), but the unique design of the Scout actually audibly rejects them instead of just not reproducing them well! I think you should still be able to get a decent and full sounding response when cutting out some of those fundamental frequencies- I do, but again I don't play a 5 string or go for a very bass-heavy tone.
Click to expand...

It's happening on a 4 string tuned normally as well. I'll try it, but I really don't think it's a matter of EQ. The new Scout I played at GC last weekend did not do what I'm describing at all, if it did I wouldn't have bought one.

I'll be able to play the head through my Aggies tomorrow, so that should put to rest whether it's the head or the cab.
 
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