Question about Cambridge Soundworks BassCube 12 Speaker

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Cambridge Soundworks Basscube 12S only makes pulsing buzz noise

When I turn on the sub, it makes a very loud pulsing sound, regardless of the output level, regardless of whether I have the receiver outlet wire plugged into it or not. It does not matter what outlet I plug into in the house. In the past, it has worked just fine and only when I hadn't used it for a few months then turned it on did it exhibit this.

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  • Anonymous Jan 01, 2009

    same issue here

  • billrad62 Jan 10, 2009

    I have exactly the same problem - it just started doing this one night.
    There were no surges or any electrical problems that occurred.
    Any solutions would be appreciated.


  • oligodude Feb 03, 2009

    I have that exact same problem too. I don't know what causes it or how to fix, but I do know that Cambridge Soundworks will repair the problem or replace the speaker for a flat rate $75 fee if you call their service department. That includes return shipping. Unfortunately you must pay for shipment to them, which is probably around $40 due to the weight and size of the speaker.

  • kevinc559 Feb 06, 2009

    I spent a month fiddling with the darn thing. Finally gave up and bought a Polk. Never knew how important a sub was until it's gone! Like listening to an AM transistor radio back in the 70's

  • cpcjm66 Feb 27, 2009

    billrad62,



    Thanks for the feedback on this. Would it be possible for you to snap a photo of the area where you made the fix? Also, did you replace the zener or just fix the solder? If you replaced it, where'd you get the part? Finally, how'd you locate the issue - just visual inspection or using a meter?



    Thanks again!

  • cpcjm66 Feb 28, 2009

    billrad62,



    OK, I'm into the amp board and I found the 4 zeners. Disclaimer - I'm not an electronics guy but I'm trainable. There are two near the edge of the power board that are easy to get at and there are two a bit further toward the heat sink that aren't as easy to get to. The two easy ones show evidence of excess heat in the traces on the board they connect to. But when I release one leg on each and do an ohm meter check across them, I get about 814 ohms one way and infinity the other - indicating neither is open or shorted. I'd expect zero both ways if shorted or infinity both ways if open.



    So, before I keep pulling more components off, I figured I'd ask if you remember which diode or diodes you replaced? And was there any evidence of heat on the board like I'm seeing?



    I can find the actual diodes on ebay fortunately - probably about $10 to get 5 shipped so that's good. Just not real sure they're shot yet.



    Thanks for the help so far.

  • cpcjm66 Feb 28, 2009

    billrad62,



    OK, I'm into the amp board and I found the 4 zeners. Disclaimer - I'm not an electronics guy but I'm trainable. There are two near the edge of the power board that are easy to get at and there are two a bit further toward the heat sink that aren't as easy to get to. The two easy ones show evidence of excess heat in the traces on the board they connect to. But when I release one leg on each and do an ohm meter check across them, I get about 814 ohms one way and infinity the other - indicating neither is open or shorted. I'd expect zero both ways if shorted or infinity both ways if open.



    So, before I keep pulling more components off, I figured I'd ask if you remember which diode or diodes you replaced? And was there any evidence of heat on the board like I'm seeing?



    I can find the actual diodes on ebay fortunately - probably about $10 to get 5 shipped so that's good. Just not real sure they're shot yet.



    Thanks for the help so far.

  • deadly1
    deadly1 Apr 30, 2009

    This is the first time I have used this site. I like the concept. Anyway, I have a similar problem to the ones I've read. After owning the BassCube 12 for almost 10 years, it recently failed and was emiting a loud, fixed tone. After pulling it apart, I found the problem. I'll try not to get too wordy. I should also add that I am an electronics technician/designer and have been for almost 30 years. First clue: "Made in China" silkscreened on the cover plate and evident in the entire design of the product. Second clue: Burnt residue on the corner of the power PCB. I should also mention that I don't have the "S" version of the BassCube12 and do not know what differences. Usually, serious overheat/overcurrent problems will damage to PCB and cause it to delaminate. However, I'm going to guess that most of the problems can be attributed to the same things: cheap capacitors. In my case, the residue was easily removed with no damage to the PCB. This was an indicator that the cheap Chinese capacitors vented and the very hot electrolyte vented. The "X" stamped in the top of the cap (capacitor) is where the electrolyte is supposed to vent, but mine vented out the bottom and all over the PCB surface. Capacitors have a finite lifespan (usually found on their datasheet) and I have replaced quite a few of the cheap ones in the last 18 months in other products (CD monitor, computer power supply, etc.). As a result of this cap venting, it damaged some other parts on the PCB, including R63, ZD3 & 4 and C26 & 27. Since I don't want to have to do this again, I'm going to replace all of the electrolytic caps in the power supply section with good quality parts and maybe some of the others as well. The semiconductors will get tested for basic functionality (using a DMM) as will the resistors. ZD3 & 4 are 1N4744 parts which are 15V zener diodes. For the person(s) capable of replacing these parts themselves, all of the parts can be ordered from Digikey.com, with the large 6800uF caps as the most expensive part at $3.73 ea. The zeners are $0.124 ea in qty of 10.



    Does anyone know the value of R63, as mine was damaged and had the color code bands burned away?

  • parris134 May 25, 2009

    Hey, just recently got my hands on an old BaseCube 10, but have a come and go buzzing sound. Almost like it was blown, but only every now and then. I opened her up and saw that there were burnt spots around the R63, and ZD3 and ZD4 (diodes). I really want to replace them, but havn't been able to find a schematic. Has anyone figured out the resistance of the R63? And what do i use for the diodes?

    Thanks a bunch!

    -Parris

  • Anonymous Nov 22, 2016

    Does anyone know what to replace the R62 and R63 resistors with mine are burnt that I can't read them. Jim

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Hey! So i fixed my problem! This is for the BassCube 10
Like i said before i saw that the circut board was burnt near the diodes ZD3 & ZD4, and the resistor R63. Thanks to Deadly1 and BillRad62, i figured it out. The R63 is a 1200 resistor, and the diodes are 15v zeners. I went with 3x 5.1v zeners to replace ZD3, unfortunately Rip-Off-Shack (Radioshack) didnt have 3 packs of these so for the ZD4 i put a 12v and 5.1v. Which exceeds 15, but seems to work without a problem. Hope it helps!

Posted on May 26, 2009

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I had the same problem and it was the -15v supply smoothing cap C29 that was bad. I do see that the R62/R62 and zeners are both running very hot - I think this type of "brute-force" regulation is not good design - all it needs is a power transistor biased by the zener to provide proper regulation. Also the PSU is live and these components are therefore hot all the time the unit is plugged in the auto-on function controls the amp after the PSU, so I think I will alter the PSU design to add that as this has been a great unit all the time I have had it...

Posted on Jul 26, 2013

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OK, my sub is back up and running. I finished replacing parts this afternoon, but I had some other work to do on the PCB. Here's how you can troubleshoot problems on most electronic equipment (including your BassCubes): inspect the entire PCB visually. Look for burned parts or parts that are cracked or damaged in any other way. That's a good indicator of the first batch of parts that need to be replaced. The next batch can be tested statically using a meter (to get more accurate readings, it may be necessary to unsolder one lead of the part and re-measure); caps should read near their rated value; resistors also; diodes will read open in one direction and considerably lower in the other; transistors read like two diodes connected end to end (anodes together or cathodes together); if you're not into electronics, don't bother trying to test the ICs. If I don't have an o-scope around, I'll just order new ICs and replace them too. Also, as I was putting my BassCube back together, I noticed how many poor solder joints I found and what poor components as well. At work, I would always inspect all solder joints under a microscope. If you don't have any magnifiers, just touch up all of the solder joints. That's what I did on my BassCube. I found quite a few bad joints and fixed those as well. Oh, one last thing: take photos of the PCB so you don't lose track of anthing you remove and replace. I hope that helps people out. Thanks to parris134 for the value of R63 (although I should have figured that out myself).

Posted on May 29, 2009

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I have solved my issue with the basscube 12s - I found a bad zener diode that regulated the voltage
to one of the amplifiers power supplies. It was caused by a cold solder joint during manufacturing of the
circuit board. The amp is located behind the heatsink on the back of the cabinet. This symptom could
be caused by any of the components in the power supply circuits. Hope this helps!

Posted on Feb 26, 2009

  • billrad62 Feb 27, 2009

    I did the repair a few months back so don't remember the voltage of the zener but I used a combination of a meter and visual. There are 4 plus/minus supplies that provide bias for the amps. I think they are
    +/- 15Vdc. I couldn't find them locally as 15 volt zeners so had my wife stop at Radio Shack and
    she bought 3 each 5.1 zeners and I soldered them together - hmmmm I guess I remember now after all.
    Once you unscrew the heatsink (there are a lot of screws- due to the vibration I'm sure) you can see
    the small circuit board and all four circuits are similar so you would be able to see the zeners. Measuring the voltages you should get around 14 or 15 Vdc unless there is a failure as mine did.
    The weakest link in the circuit is the zeners so guess what goes first. Good Luck


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When I googled the BassCube 12S, I found numerous reports of this issue. It appears that it means the amplifier is fried, and the only solution is to replace it. I recently sent mine back to Cambridge Soundworks for repairs, and am waiting for it to return. The shipping cost for me at UPS was $55, which makes the total cost of repair $130 when you add it to the $75 flat fee from CS. I hope it lasts long enough to be worth it, but I couldn't find a comparable new sub for the same price.

In regards to the wireless internet interference reported by Gneiss, it would be 'nice' if my problem was that simple, but I don't have a wireless router. And if you heard the sound most of us are referring to, I don't think it could be mistaken for an interference signal. As reported by others, there does not seem to be any precipitating cause for the amplifier to self destruct. It will be working just fine and then spontaneously die without warning.

I'll post again if my repair is successful.

Posted on Feb 25, 2009

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I had the a similar problem, it was picking up my wireless internet signal. I think any type of emitting electrical device, if in close proximity, can be pick up by the speaker.

Posted on Feb 25, 2009

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