Stupid Combo Amp Tricks, or "how to break your practice amp input jack"

[nickpc]

So today's project was trying to get my Acoustic B50c to not be so boomy in my music room. I've tried a few things (room position, there's plenty of soft surfaces in the room and the 80's era stereo system has no issues with boom...), so where I was today:

Lows and Low-Mids turned all the way down. Boomy. Fender Downtown Express, activate the EQ and cut the bass. Boomy (but sounding really thin). Move to the middle of the room. Put a variety of pillows over the speaker. So I'm thinking this amp and this room just don't get along.

Last (and stupid) idea: Decouple from the floor with one of the memory-foam pillows!! That should help, right? Nope, still boomy.

Until it fell over on it's face, with the instrument cable plugged in.

Well, it's not boomy now!

Yep, the input jack is toast. It's soldered directly to the board, and I can't see where it's broken, but it is. If I wiggle the cable I can get a few popping noises, and the line-in works fine. This is beyond my skills to fix with a soldering iron, and right on the range of not being worth paying someone else to fix it, especially considering I was about to give up on this amp completely.

Oh yeah, the cable. The fall managed to tear the sheath out of the strain relief, so that's a goner too. And yes, I used a new/known good cable for the testing.

 

[Nebadon2000]

; Had a similar problem with my Markbass CMD 121P Combo also got wolf note when playing a D note anywhere on Bass;

I tried Ampwedge that angled cab up, got Auralex Isolation pad, moved room position, extreme EQ etc.

When I finally tried putting my MB NY 121 Extension cab [was in closet for take out only when needed] under Combo did it mostly fix problem with a little tone adjustment but if I plugged in and played NY 121 with combo same problem

I now have Mesa WD 800 and Subway 1x15 Cab in same spot sounds fantastic zero boom or woof no major tone control adjustments needed
So I fixed problem and it only cost me $1500 [on top of $ I got for my Markbass Setup]

 

[agedhorse]

A qualified tech won’t have any difficulty repairing the input jack properly. It’s not an expensive repair either.

 

[Pilgrim]

Repair it and sell it if you don't like it. Or sell it really cheap.

 

[Lefty Joe]

The good news is, now you know you ARE giving up on that amp

I've had similar dilemmas with my instr/combo. Got an active EQ bass, that should fix everything right? But no: there's still some midrange quack I can't seem to avoid, no matter how I set it ... unless I turn the lows way up, reducing whatever I play to a vague low boom -- you can't even tell what note it is, I could be playing in the wrong key and who would know?

Thing is, I didn't get this amp to be stand-alone -- I was doing what I call poor man's bi-amping, splitting signal between a bass amp with a 15", and an 80w SS guitar combo; turn the guitar amp's bass all the way down, and the bass amp's bass all the way up, then mix for balance. This works fine, but wouldn't it be nice to get the right sound with one combo alone? I guess I'll keep working on it

 

[DaveParker39]

If it makes you feel any better, I both destroyed an amp AND got electrocuted trying to "repair" a noisy input jack when I was in college.

 

[steve_ss]

My condolences on your loss.

 

[agedhorse]

If it makes you feel any better, I both destroyed an amp AND got electrocuted trying to "repair" a noisy input jack when I was in college.

Happens sometimes

 

[eniac]

 

[FullumMusic]

Proper bass traps will help the boom problem. Not that foam wedge garbage they sell for way too much money that won't reduce the low frequencies at all. Like for-real proper bass traps. I'm not gonna go into the difference, but there are a half million YouTube videos and forum threads discussion the difference between acoustic tiling/foam & proper bass traps thick enough with an air gap to reduce bass.

 

[jthisdell]

At least you got rid of the boomyness

 

[agedhorse]

Proper bass traps will help the boom problem. Not that foam wedge garbage they sell for way too much money that won't reduce the low frequencies at all. Like for-real proper bass traps. I'm not gonna go into the difference, but there are a half million YouTube videos and forum threads discussion the difference between acoustic tiling/foam & proper bass traps thick enough with an air gap to reduce bass.

Many if not most are just wrong, or opinions displayed as fact.

 

[FullumMusic]

Many if not most are just wrong, or opinions displayed as fact.

True. I mean, that seems like it's true about most music technologies videos. (cough compressor youtube vids cough).
But there are good ones there from reputable people. Biggest problem is weeding through the crap, especially if you don't come in with prior knowledge.

 

[Nebadon2000]

especially considering I was about to give up on this amp completely.

Obviously even if you fix it or buy new one still have same problem; If you are in the vicinity of GC checkout Rumble 40 or Mark Bass CMB 101 not much more than new Acoustic B50; if they have same problem GC has no questions ask returns and you will know room needs rearranged or find another room

 

[nickpc]

you will know room needs rearranged or find another room

The room does fine with my Roland Bass Micro Cube RX, and has no issues with the pair of Realistic Optimus 1000 speakers (nice 15" woofers) that I have in there. And I had even taken them out of the room to make sure I wasn't getting some weird feedback/sympathetic resonance effect from them.

Local middle school that my wife used to work at has a band program with a few basses that I've donated, so I've reached out to them to see if they want to see if they want to take a crack at it.

 

[agedhorse]

The room does fine with my Roland Bass Micro Cube RX, and has no issues with the pair of Realistic Optimus 1000 speakers (nice 15" woofers) that I have in there. And I had even taken them out of the room to make sure I wasn't getting some weird feedback/sympathetic resonance effect from them.

Doesn't work that way, it could easily be the room. You just don't understand it yet.

 

[BeyondFiredUp]

Congrats on a cool rig!

 

[Stylee Mousse]

I have a 15x15 room at home where I practice sometimes. I know anything above really sensible volume and windows rattle, room modes light up.

So I don’t turn up beyond what works. I don’t push low frequencies. A little high boost tho.

I practice through a 20 watt 112 tube combo.

 

[nickpc]

Doesn't work that way, it could easily be the room. You just don't understand it yet.

Unfortunately that's 100% accurate. The more research I do the more I realize how much more research I need to do in order to be able to address the issue!

So much for "maybe a different size driver will change it"...

 

[agedhorse]

So much for "maybe a different size driver will change it"...

Yup, not a root cause issue.