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

[Pioter]

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.

Thx for Your answear. Sooner it would be a matter of a cab I think. Sterling is an active bass with quite high amount of output. How do U think is there something I can do to target the problem? Btw Your comparison to non-working tone knob is an accurate term.

 

[39-Bassist]

So you have used another cab with the same bass and amp correct? and that cab sounded fine?
Have you disconnected the tweeter and has it the same tones even when you try your slap fix? just seeing if the cabs sound is that "dead" tone you are hearing now all the time. If so get an new tweeter or have it fixed of course.
Just wanting to clarify...thank you

 

[chadds]

An intermittent or steady contact inside your bass between the jack and some ground could reproduce what your are experiencing.

 

[murphy]

I had a cab 410s and a tweeter , arrived in the mail with the tweeter dead...
I was told it was fine...By the sender

I replaced the horn diaphragm and it was a cheap part from my music store and easy to replace...and it worked fine after.

I remember some cabs had a fuse that lit up in the crossover for the horn....Maybe it is the bulb...or the fuse

 

[JeezyMcNuggles]

Thx for Your answear. Sooner it would be a matter of a cab I think. Sterling is an active bass with quite high amount of output. How do U think is there something I can do to target the problem? Btw Your comparison to non-working tone knob is an accurate term.

Look for a shotty solder joint, or an otherwise "bad connection"

I'd pull the tweeter out, inspect it for any visual problems, then hook it back up.

Same with my bass. Check out the control cavity for anything that could be a bad connection, or a possible grounding spot.

 

[jthisdell]

You might try playing some recorded music through your cab, it will be obvious if the horn is in fact cutting out.

 

[agedhorse]

If it’s happening with your two basses, it’s not your bass.

It’s rarely (as in almost never) a short with the symptoms you are experiencing.

It’s almost certainly an intermittent diaphragm or an intermittent terminal or component on the crossover.

Troubleshooting will reveal the problem without guessing.

 

[alexgeddy]

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

Get some deoxit and one at a time remove each connector for the tweeter. and the crossever... Spray them and work them on and off the connector... If this doesn't help check the wiring from the connector to the other end. Sometimes the wire corrodes under the insulation and u can't see it. Hsve had this happen numerous times. Good luck!!

 

[agedhorse]

Don’t spray DeOxit anywhere near speakers, that’s the wrong tool for the job and can create problems that don’t currently exist.

At speaker level, the connector geometry doesn’t benefit from miracle cure-all spray.

First identify the actual problem, then the proper repair will become obvious.

 

[Pioter]

Thank You all for Your time with my post! I'm glad that I'm a part of this community.

But to the point...

Next Tuesday I'll try to prepare exact "documentation" (sound samples and pics) to introduce within this forum.

@jthisdell good idea! I'll try it too.
@39-Bassist cab was checked with different guitar and amp. I turned the tweeter off to check if I had only 'a bad day'. Of course in this case there was no problem as you might guess
@JeezyMcNuggles thx for responce. To be sure I tried to connect my bass to the interface and did not found any issues.
@agedhorse You tempt me to check it with alternative diaphragm. I'll see if I can find one in the local area.

Thx to U all.

 

[Pioter]

btw @agedhorse I think You will know, will it be appropriate diaphragm?:
Fostex,Fostex,Foster N30,N08,H025N08

 

[agedhorse]

I don’t recall, though the replacement diaphragm may be available on the website.

 

[Pioter]

Ok guys, here it is.

I'm linking one audio file with issue sample ( [This invalid link has been removed] - if U would have problems with download please let me know): to about 12s - muddy (problematic) sound; in about 12s hard pop ("reset" as I called it before); then clear sound with highs (desired); then the sound is getting muddy again (I would say "ultra vintage" :-/ ); few lower notes played; and again muddy as hell. And that is my problem in one sample.

I tried to play in the same place on strings. Eq on guitar and amp set flat. Tweeter about 80% open (wide open would be 100%). I'm attaching pictures also but everything seems to be Ok. I have checked impedance on one of the main speakers. It is about 12ohms (think is fine cause those are 16 ohms eminence).
Problem is more obvious when listened live. I recorded it using small condenser mic to enhance highs from about 60cm distance. Please listen quite loud with headphones or quality speakers (not laptop ones). Maybe I'm exaggerating but... Damn, it does not work as it should be.

 

[agedhorse]

Well somebody's been in there because the woofers were not originally soldered. It is the factory part number however, so maybe it was replaced at some time, or??? The woofers used the same connectors used elsewhere throughout the speaker. There's also that solder splash on the cap, which is not a factory "accessory".

At this point, I don't know what's going on. It's possible that there is some mechanical damage to the diaphragm from abuse, or perhaps from a previous repair attempt removing and reinstalling it.

 

[abarson]

img_20211208_190442-jpg
It looks to me like someone got careless with a soldering iron and the insulation on the top black wire is compromised. I'd replace that wire pair.

img_20211214_203804-jpg
It looks like there might be a cold solder joint on the black wire. But as @agedhorse pointed out it is supposed to be done with spade connectors and not soldered.

If it were mine, I'd redo all the wiring to specification, just to remove any errors of the previous hack. You can make your own twisted pair using a simple jig and power drill.

 

[agedhorse]

I think the solder splash will come off with a little picking at it.

The FastOn connectors are the .187" slim tab style, 18-22 size. They need to be installed with the proper tool, NOT pliers or dikes.

 

[byacey]

The background hiss disappearing is a very solid clue. This rules out the pickups, basses, and many of the other things that some were suggesting.

If you have access to an audio oscillator, you might want to sweep from 1Khz and up; if it's an intermittent diaphragm, the problem should show up as you're sweeping through the frequencies. You might also try tapping on the crossover with a steady tone signal driving the cabinet to see if it's intermittent connections on the crossover board.

 

[agedhorse]

Sweep at very low levels only, or you can create a new problem.

 

[Pioter]

Thx for your comments. I'm glad that this is not an ear fatigue after all.

Solder splash on the wire was removed simply by scratching and the wire under the splash was in good condition.

At this moment everything I can do only by myself is to change the diaphragm in the tweeter. I don't have an audio oscillator and my soldering skills are poor.
My hope has gone... If diaphragm change does not bring any positive results, I will have to give the cab to the technician but I doubt that there is a competent one in my area.

Last thing. What is the yellow capacitor, with solder splash on it, responsible for? I checked it with multimeter and its impedance could't be measured (pikes on both sides).

 

[agedhorse]

Leave the cap alone.

Try replacing the diaphragm, see what that does.