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Nasty G to Bb Buzz In B-450 Combo Repair

SurferJoe46

SurferJoe46

Feb 22, 2010
9,057
763
The Bitterroot Mounts, Montana
#1
My brand new Acoustic B-450 developed a really bad buzz on certain low notes, and I thought I'd ripped a speaker.

It couldn't be!!!!!! (I couldn't believe that I had done anything wrong since I haven't had it over half-volume yet anyway!)

I used a flashlight to look through the grill cloth and could see a couple of screws around the speakers were actually sailing proud!

It looked like it was gonna be a two- or three-week loss if I took it back to GC for free repairs - so I decided to take a look at it myself.

I took some pixs of the repair - and believe me I didn't want to harm or damage anything - nor did I want it to be obvious that I had even opened the case if there was a possibility of a warranty denial and big stinking argument in the near future!

It was so easy that a caveman could do it!

Really! I think the pixs with the entries are pretty self-explanatory..........

Here goes - hope it helps! (PS: Please iggy the misspelled "screws" on one of the pixs. I was in a hurry! :spit:)

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When you are going back together - just gently insert the grill frame and then just use you thumbs ON THE FRAME to push it back in. The Velcro does all the work holding it in.
 
#4
I just gigged it today - but only about 1/4rd vol - it was snowing out and we had to move into a rather small enclosed room.

So far it has been quiet. I kinda scared myself the other day in my house with it about 1/2 vol and just by itself - and I got another bad rattle - but it was my door on the fireplace, which was right next to the amp!

Phew!

If these screws get loose again I wonder if I want to risk making them tight for life with some epoxy or Elmer's Yellow glue on the threads.

MAYBE a set of small machine screws and nuts/washers would be good - I dunno yet.

I can't wait for an opportunity to run both the B450 and the B410 at more than 50% some day! Spring is coming and I have a lot of outdoor playing sessions coming up.

Last decent day I fired it up without the side cab and on the back patio at home with the guys from the combo I am working with we were heard over two miles away - well, the bass was anyway! :hyper::hyper:
 
#5
Well I since found out that it wasn't just a loose speaker. The screws are really not wood screws - which I hadn't investigated up to this point when I only tightened them a little.

After the last gig and after the tightening the speakers up, I moved the noise to a different frequency and it got so bad I shut down the cab and fired up my old Peavey to finish the set.

Once I got the B450 home, I took one of the speakers actually out of the front of the cab and guess what I found?

It's the spade connectors that are all loose!

Each speaker has a double lug on it for the amplifier and parallel speaker(s) connections and the female sides of the wire ends are all wobbling around and when you hit certain harmonics, they rattle and connect-disconnect-reconnect-disconnect again and again - in response to the note you are playing.

Some notes don't bother them at all. Hit some others and all hell breaks loose!

At first (this time) I thought it might be the wire pigtails themselves sitting too close to the speaker cones and they would only hit at certain volume or cone deflection levels - but no-o-o-o-o !

I tried to move the spade females to see if there was a spot where they got tighter and that made some things better, some worse.

I just fired off an e-mail to the factory to ask them what to do. It wouldn't bother me to actually solder the connections onto the lugs - and that may be where this all goes.

I'll post when I get an answer.

And I am still very positively impressed by the amplifier. I just think they have a little parts connection quality control problem here, that's all.
 
#6
More than 24-hours later and no answer from Acoustic - I guess I stumped them or they just don't care about service and warranty relations.

OK - so I went ahead and soldered pigtails on the speakers and then used automotive quality electrical connectors and after it was all done (1-hour for the tear-down, taking both 10" speakers out and soldering pigtails on them and splicing the other wires then back together) it was corrected and there is NO NOISE any more in the system.

PAY ATTENTION TO THE WIRING POLARITY HERE!​

I gigged it in a small venue today and after that took it outside of my house to hammer it a little more.

Clear, clean and no strange noises at all.

The sound ranges from chocolaty smooth to a good crack and crackle when slapped. The speakers are very compliant and with the horn ON or OFF I can hear the difference now.

One thing to do is make sure with the wires you install if you make this repair/conversion - is to shoot a few staples into the interior to hold the wires out of the cones from the backside. I feel they can migrate to bad places when you truck the unit around and if you let it lie down to haul it.

Make sure to use wire that is just as large or slightly larger in gauge as the original wiring. You don't want to create any resistance problems now.

It seems that automotive splices and connectors are really a lot tougher than the puny little spades and connections that are standard for the electrical industry and they hold more tenaciously than their flimsy electronic brethren.

I used some shrink tuning on areas where I thought there might be a future problem, but really I prolly overkilled that and it wasn't necessary at all.

At this point I am rather miffed at Acoustic for their lack of support or concern, whichever it is and that does NOT make me happy. Maybe today and yesterday were Korean holidays though and they aren't on my Google calendar.

If you should buy one of their products - fine as they are - it would be good to understand that you are on your own with any problems you may have after the original sale.

DO YOU HEAR ME NOW, MR. ACOUSTIC???​
 
#8
C'mon! A couple of loose wires?

That's not grounds for condemnation of the whole line - the PEOPLE who manage the company, maybe.

The bean-counters, more likely: these are the real culprits in customer complaints and problems resolving an "issue" as anything that creates waves, usually sinks a few rats. .

Their products are pretty good. You can't get this much clean and precise power for the dollar any more in almost anything else.
 
#9
SurferJoe46 said:
C'mon! A couple of loose wires?

That's not grounds for condemnation of the whole line - the PEOPLE who manage the company, maybe.

The bean-counters, more likely: these are the real culprits in customer complaints and problems resolving an "issue" as anything that creates waves, usually sinks a few rats. .

Their products are pretty good. You can't get this much clean and precise power for the dollar any more in almost anything else.
Click to expand...

Why would you not blame the bozo who tightened the screws? You know what...blame whomever you want. The fact is an amp with loose screws and speaker connections got through their QA/QC process. The problem was bad enough that an end user (i.e. you) has already self-diagnosed/self-repaired problems two times.

Maybe it was shoddy workmanship, chintzy materials faulty design, and/or bad quality control, but what you experienced with your amp is grounds for immediate dismissal of the entire product line. For jeebus sake, it's not a car. RELATIVELY NEW SOLID STATE BASS AMPS REQUIRE NO MAINTENANCE!

It completely amazes me that you're still defending their product! :confused:
 
#10
This isn't brain surgery either. It's just two loose speaker spades and what I though the real culprit was, and wasn't - as the screws being loose or tight didn't really repair the problem.

But, yeah - I SHOULDN'T have had to enter a new cab and finish what the assembly line trench people should have done before the unit got out.

On the other hand - the company is making a big splash comeback, and I think a little slack for growing pains is not unwarranted. It still out thunders anything in it's dollar range and smokes a lot higher-end units too.

It DOES weigh a lot though! 78 lbs!

Next week I am also getting their B-115 to go with the B-410 I already got for the B-450.

PS: The B-410 didn't have the same problems with the loose spades. Whyzzat? I dunnow.
 
#12
Infiltration12 said:
Tag- having a rattling problem with my Schroeder 410, this may be the answer.
Click to expand...

TY --- something good may come from this revelation then.

I wonder how often and commonplace across-the-manufacturer's lines this may be occurring? I don't see nor think that JUST Acoustic is buying these connectors/spades.

And --- Acoustic isn't manufacturing the spades anyway - so why blackball them for materials upon which they have little control and just assume that their parts supplier is making good parts.

Sometimes things like this are "progressive revelation" to ANY company and I feel that a certain honeymoon time period is allowable to a company that's trying to make a big comeback after years of inactivity and loss of public profile.

Maybe this is a good place for people to start looking when they experience rattles and crackling and cannot find a likely culprit.
 
#13
SurferJoe46 said:
TY --- something good may come from this revelation then.

I wonder how often and commonplace across-the-manufacturer's lines this may be occurring? I don't see nor think that JUST Acoustic is buying these connectors/spades.

And --- Acoustic isn't manufacturing the spades anyway - so why blackball them for materials upon which they have little control and just assume that their parts supplier is making good parts.
Click to expand...

Even if Acoustic isn't manufacturing the spades, the problem is that they elected to use them...most likely as a cost reduction measure. Just imagine what other cost cutting measures they employed (e.g. cheap, failure-prone electronics) and how that will affect you down the line.

SurferJoe46 said:
Sometimes things like this are "progressive revelation" to ANY company and I feel that a certain honeymoon time period is allowable to a company that's trying to make a big comeback after years of inactivity and loss of public profile.

Maybe this is a good place for people to start looking when they experience rattles and crackling and cannot find a likely culprit.
Click to expand...

The only thing that the current crop of Acoustic products has in common with their predecessors is the name and the baby blue graphics...I know, I regularly played through old Acoustic amps in the early 90s. They WERE solid and dependable. It's painfully clear that the current crop is an entry level line, very much like Behringer with the same inherent problems, hoping to ride on the coat tails of "old Acoustic"...heck, didn't Jaco play a 360?

We've already established that we have VERY different expectations of our gear but it just bums me out that we're collectively "lowering our expectations" when BS like apparently becomes acceptable and commonplace. :(
 
#14
Hey Surfer Joe,
Thanks a lot for contributing what you learned. I just picked one of these up and I'm getting what I believe to be the same rattle you described. Unfortunately, your pics aren't showing up! Can you repost them? This rattle problem seems to be fairly widespread...

I'm concerned, though, because in my amp it appears to be coming from where the B600H head attaches inside the cabinet. Anyone else have this issue?

Thanks in advance for any responses.

best,
Mishka
 
#15
I have the pixs here somewhere - but I know the separator between the cabinet and the amp can vibrate and I just shoved some neoprene foam in there. No more problems.

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This shows the bolts that hold the drivers in - they are NOT wood screws but there's Nut-Serts in the front panel, so they won't strip or fall out.

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You may only have to pull one driver to access the whole internal wiring system - that's the way I did it::

You'll see these troublesome wire connectors on the lugs of the back of the cages for the drivers, just like any other speaker situation.

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If those connex are your problem, this'll fix it.
 
#16
SurferJoe,

I just bought an Acoustic B450 mkii and they have apparently still not fixed this quality control issue. Can you please repost the pics? Did your repair hold-up over the long run on your B450? I'm considering taking this back to GC, but it seems to be a great bass amp otherwise.

Thanks for your earlier posts on this topic and any help you might give me.

Dave
 
#17
I had a loss of pixs on Picasa that I'll have to repost very soon. Thanks for the kudos and I'll look into this today.

I still use this unit and on top of a B115 it can pretty well fill most moderately sized auditoriums with nice clean sound. The DI in the back has been a great thing too.

There have been ZERO problems with this unit. So far it's been a very good buy.
 
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#18
SurferJoe46 said:
I had a loss of pixs on Picasa that I'll have to repost very soon. Thanks for the kudos and I'll look into this today.

I still use this unit and on top of a B115 it can pretty well fill most moderately sized auditoriums with nice clean sound. The DI in the back has been a great thing too.

There have been ZERO problems with this unit. So far it's been a very good buy.
Click to expand...

SurferJoe46 - Hey, I discovered that my buzz on B450 was NOT the speaker spade connectors. I didn't even take the grill off. It seemed that the rattle was coming more from the amp head, so I removed the six screws that hold it in place and carefully slid it out. I noticed that there is a large toroidal transformer right at the location where I suspected something was rattling against metal frame/cab. I tightened the large nut that secures the transformer and also zip-tied many of the wires together for strain relief and to prevent them from rattling against side of head. Put it all together, and it significantly reduced (if not eliminated) the rattle/buzz. I'll keep an eye out for the buzz on the speaker spade connectors. If you ever find photos...they might still be useful to me. I happened upon another post of your in which you salvaged a B450 that was crushed after falling off truck....pretty cool.

Thanks,
Dave
 
#19
Make sure that the wooden "tray" under the amp, which also doubles as the top of the speaker-driver "box" isn't hitting the bottom of the amp chassis.

I used some very dense hard foam exercise sheets that my wife used to use in her physical therapy class as a floor mat to keep them apart --- only at very high volume I might add.

Just stuff some into that small gap.

It seems when the amp is on concrete, it couples and starts it's own resonance that makes the top of the cab smack the bottom of the amp.

A quarter of an inch more clearance between the two components here would be nice, but the foam takes the nasty away fair enuff.
 

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