[Mesa 2x10"] Problem with disappearing highs during play

Pioter

Pioter

Aug 17, 2021
22
8
1,551
Poland
#1
Hi.
I have problem with my Mesa 2x10 Powerhouse cab (probably). When I'm playing, sound gets muddy and unclear like all of the high frequencies just disappeared, but it occurs "quasi" randomly. I hear the lack of highs (!You know what i mean!) especially when playing in mid registers and sometimes in lows. It almost never occurs with highs (D and G strings - standard tuning). Funny thing is that when it happens I can "reset" the sound by popping some high note on G string (high D for ex.) and then everything backs to normal, till I play mentioned "bad" notes again.
I play on EB MM Sterling with Ampeg SVT 3 Pro. Cab was checked also with Cort A4 and different amp (GK 700 rb II) with the same result. At first I thought that it might be some problem with horn/tweeter so I checked the coil of tweeter with multimeter but everything was ok (impedance). Mechanically, coil seems to be ok as well.
I know that it sounds silly ("lack of highs in low registers" ;) ) but I mean that the sound is muddy and unpleasant. Maybe I'm seeking in the wrong place. Maybe it is a bass/mid speaker issue or some problem with crossover setup? Any thought on this?
Thank You for help.

Btw English is not my native language. Thx for understanding :)
 
#2
Have you checked all of the connections on your speaker wires? I'm also wondering if it is a crossover problem. Check connections going to the crossover and look at it for physical issues as well.
 
  • Like
Reactions: trevcda
#5
two fingers said:
Have you checked all of the connections on your speaker wires? I'm also wondering if it is a crossover problem. Check connections going to the crossover and look at it for physical issues as well.
Click to expand...
Thx. I'll do this for sure. If it would be a crossover issue, what are your suggestions? Btw I found somewhere on TalkBass that someone have similar problem with "muted highs" but there was no solution response.
 
Last edited:
#8
I forgot to mention that when I "reset" the sound by popping (as I described above), an audible hiss can be heard from the tweeter (I guess) and the sound is clear, but after playing lower notes (the "bad" ones) hiss disappears.
 
#10
agedhorse said:
It’s possible that the tweeter diaphragm is intermittent, or that there is an intermittent connection within the crossover or wiring within the cabinet.
Click to expand...
Thx. I checked the impedance (multimeter) on tweeter diaphragm and it is about 7,6 ohms and took a close look (bare eye) at its coil wiring. Everything seems to be ok there. Crossover looks fine as well (Im not a technician so I can be wrong). I did not check wiring on main speakers.
 
#13
Pioter said:
So we aren't 100% sure, right? I can check it with 9V battery though...
Click to expand...
Again, unless the intermittent connection is in fault mode, it will not test bad. Do NOT use a battery on a tweeter unless you want to insure that it’s bad (even if it wasn’t defective before).

do you have another tweeter to substitute in place of the suspected intermittent tweeter?
 
  • Like
Reactions: byacey and AudioTaper
#16
Pioter said:
Hi.
I have problem with my Mesa 2x10 Powerhouse cab (probably). When I'm playing, sound gets muddy and unclear like all of the high frequencies just disappeared, but it occurs "quasi" randomly. I hear the lack of highs (!You know what i mean!) especially when playing in mid registers and sometimes in lows. It almost never occurs with highs (D and G strings - standard tuning). Funny thing is that when it happens I can "reset" the sound by popping some high note on G string (high D for ex.) and then everything backs to normal, till I play mentioned "bad" notes again.
I play on EB MM Sterling with Ampeg SVT 3 Pro. Cab was checked also with Cort A4 and different amp (GK 700 rb II) with the same result. At first I thought that it might be some problem with horn/tweeter so I checked the coil of tweeter with multimeter but everything was ok (impedance). Mechanically, coil seems to be ok as well.
I know that it sounds silly ("lack of highs in low registers" ;) ) but I mean that the sound is muddy and unpleasant. Maybe I'm seeking in the wrong place. Maybe it is a bass/mid speaker issue or some problem with crossover setup? Any thought on this?
Thank You for help.

Btw English is not my native language. Thx for understanding :)
Click to expand...

On a side bar, you English is very good. I hear it mangled a lot worse by American citizens that have lived near for generations..LOL!! I hope your problem is resolved soon.
 
  • Like
Reactions: AudioTaper
#18
Perception can vary from reality. Is the tweeter actually cutting out, or are you having problems getting an even tone across the range of your instrument?

Consider that the low frequencies generated by the cab will be pretty much omnidirectional, meaning they radiate equally in all directions. As the frequency goes higher, the size of the sound wavelengths gets smaller and smaller. At some point the drivers are sufficiently large to start controlling the direction of the soundwaves. More and more of the sound will start shooting out in front of the cab. Eventually the pattern can tighten so much that it is essentially a narrow beam. If the cab is flat on the floor, this beam of sound will shoot out below waist level, so you won't hear it.

Keep in mind, the 210 PowerHouse is a 2-way design, and te 10s will have different dispersion characteristics than the tweeter. So you might hear the tweeter and low frequencies fine. But you may lose the high-range coming from the 10s.

Another problem is when you place two drivers next to each other, you get comb filtering/destructive interference. The destructive interference results in the formation of a pattern something like this along the axis the speakers are aligned on.
upload_2021-12-9_13-0-2.png

The only place where the propagation path for both drivers is the same is on axis. In other words, if you are standing on the forward axis, the sound from both drivers will arrive at your ears at exactly the same time. But if you are off axis, the sound from the drivers that is closest to you will arrive first. The different arrival times result in phase variances.

When the signals arrive in phase you get summation, and when the signals arrive out of phase you get cancellation that produces a null. The angle of the secondary lobes is determined by driver spacing and wavelength, which is determine by frequency. This means the off-axis frequency response will be uneven, so some frequencies will be emphasized, while other frequencies are totally missing.

The orientation of the drivers is another thing to consider. The image above the shows dispersion when the drivers are aligned vertically.
upload_2021-12-9_13-14-39.png

The lobes form along the axis the drivers are aligned on. This results in a narrower dispersion pattern and also comb filtering off axis. However, the dispersion perpendicular to the axis is not affected. So in this image, the horizontal dispersion would be the same as the dispersion as one of the drivers.

Likewise, when the drivers are aligned horizontally the problems occur along the horizontal axis and vertical dispersion is not affected.

To fix the problem tilt the cab and aim it at your head. The on-axis response is where the best frequency response occurs. If you move around, consider whether vertical or horizontal alignment is best for your needs.

I usually elevate my cab to about waist level with the drivers aligned vertically. I tilt the cab back a bit so the primary lobe is aimed at my head.

Good luck!
 
  • Like
Reactions: jeff7bass, tblurker and Gizmot
#19
Wasnex said:
Perception can vary from reality. Is the tweeter actually cutting out, or are you having problems getting an even tone across the range of your instrument?

Consider that the low frequencies generated by the cab will be pretty much omnidirectional, meaning they radiate equally in all directions. As the frequency goes higher, the size of the sound wavelengths gets smaller and smaller. At some point the drivers are sufficiently large to start controlling the direction of the soundwaves. More and more of the sound will start shooting out in front of the cab. Eventually the pattern can tighten so much that it is essentially a narrow beam. If the cab is flat on the floor, this beam of sound will shoot out below waist level, so you won't hear it.

Keep in mind, the 210 PowerHouse is a 2-way design, and te 10s will have different dispersion characteristics than the tweeter. So you might hear the tweeter and low frequencies fine. But you may lose the high-range coming from the 10s.

Another problem is when you place two drivers next to each other, you get comb filtering/destructive interference. The destructive interference results in the formation of a pattern something like this along the axis the speakers are aligned on.
View attachment 4499208
The only place where the propagation path for both drivers is the same is on axis. In other words, if you are standing on the forward axis, the sound from both drivers will arrive at your ears at exactly the same time. But if you are off axis, the sound from the drivers that is closest to you will arrive first. The different arrival times result in phase variances.

When the signals arrive in phase you get summation, and when the signals arrive out of phase you get cancellation that produces a null. The angle of the secondary lobes is determined by driver spacing and wavelength, which is determine by frequency. This means the off-axis frequency response will be uneven, so some frequencies will be emphasized, while other frequencies are totally missing.

The orientation of the drivers is another thing to consider. The image above the shows dispersion when the drivers are aligned vertically.
View attachment 4499224
The lobes form along the axis the drivers are aligned on. This results in a narrower dispersion pattern and also comb filtering off axis. However, the dispersion perpendicular to the axis is not affected. So in this image, the horizontal dispersion would be the same as the dispersion as one of the drivers.

Likewise, when the drivers are aligned horizontally the problems occur along the horizontal axis and vertical dispersion is not affected.

To fix the problem tilt the cab and aim it at your head. The on-axis response is where the best frequency response occurs. If you move around, consider whether vertical or horizontal alignment is best for your needs.

I usually elevate my cab to about waist level with the drivers aligned vertically. I tilt the cab back a bit so the primary lobe is aimed at my head.

Good luck!
Click to expand...
Thank You for a comprehensive answear! It is very inspiring. I have an idea. Maybe I should record the issue and compare both sounds. I would know then if it is a perception problem or not. :)
 
  • Like
Reactions: Lobster11, Wasnex and Aqualung60
#20
Pioter said:
Hi.
I have problem with my Mesa 2x10 Powerhouse cab (probably). When I'm playing, sound gets muddy and unclear like all of the high frequencies just disappeared, but it occurs "quasi" randomly. I hear the lack of highs (!You know what i mean!) especially when playing in mid registers and sometimes in lows. It almost never occurs with highs (D and G strings - standard tuning). Funny thing is that when it happens I can "reset" the sound by popping some high note on G string (high D for ex.) and then everything backs to normal, till I play mentioned "bad" notes again.
I play on EB MM Sterling with Ampeg SVT 3 Pro. Cab was checked also with Cort A4 and different amp (GK 700 rb II) with the same result. At first I thought that it might be some problem with horn/tweeter so I checked the coil of tweeter with multimeter but everything was ok (impedance). Mechanically, coil seems to be ok as well.
I know that it sounds silly ("lack of highs in low registers" ;) ) but I mean that the sound is muddy and unpleasant. Maybe I'm seeking in the wrong place. Maybe it is a bass/mid speaker issue or some problem with crossover setup? Any thought on this?
Thank You for help.

Btw English is not my native language. Thx for understanding :)
Click to expand...
There's probably a short in the tweeter. Or, there's a short in your pickups. The pop, knocks it back on. If you can kick it back on by smacking your bass, it's the bass. Otherwise, that quick input surge of the pop is what's kicking it back on, and it's the cab.

My SR, and my talman both had shorts, that I could smack back on. Sr in the preamp, talman in the P pickup.

Sr would cut out completely, but the talman would just dull out. Kinda like what you're describing. Low output, and as if the tone knob was down.
 
Last edited:
You must log in or register to reply here.
Top Bottom
Back