RedSub BT5110 - gone wonky, call it a day?

[neepheid]

My amp (RedSub BT5110) half died last night - power stage stopped working, DI was still working out to the PA so I guess the preamp is fine.  Thought it might be overheat protection kicking in, but I checked today and the fan is spinning (which was my first suspicion).  More weirdness - the headphone output isn't working (although the logic to detect the plugging in of headphones is working and kicks in the mute for the external outputs).  I put the headphones into the speaker out and I am getting a signal but it's hissy (not a fair test as headphones are pretty high impedance (32 ohms at least?)) But that's more than what was coming out of the power stage last night.

 

Maybe 11 years, many gigs, many more rehearsals have taken their toll and it's time to move on.  I can't gig it if I can't trust it.

 

Thoughts?

[itu]

And FX loop + cable has been already tested?

[neepheid]

3 minutes ago, itu said:

And FX loop + cable has been already tested?

 

It doesn't have an FX loop with which to test that.

[Mottlefeeder]

When you talk about logic to mute the amp when the headphones are plugged in, are you sure it is logic controlled, and not just power amp to switched headphone socket with a couple of resistors to cut down on the signal.

 

If the latter, it is a weak point and it might be worth squirting switch cleaner into the socket assembly (not water dispersant WD40) and inserting/removing the headphone plug several times to see if that clears the problem.

 

David

[sandy_r]

On 03/09/2023 at 13:36, neepheid said:

My amp (RedSub BT5110) half died last night - power stage stopped working, DI was still working out to the PA so I guess the preamp is fine.  Thought it might be overheat protection kicking in, but I checked today and the fan is spinning (which was my first suspicion).  More weirdness - the headphone output isn't working (although the logic to detect the plugging in of headphones is working and kicks in the mute for the external outputs).  I put the headphones into the speaker out and I am getting a signal but it's hissy (not a fair test as headphones are pretty high impedance (32 ohms at least?)) But that's more than what was coming out of the power stage last night.

 

Maybe 11 years, many gigs, many more rehearsals have taken their toll and it's time to move on.  I can't gig it if I can't trust it.

 

Thoughts?

 

If your amp has Mute logic (rather than just the headphone jack switching out the speaker), then it could be that the mute switching logic circuitry has failed - since both speaker and phones signal paths will be switched, the failure mode could affect both  😞

 

[Edit] ...looks like the Master Vol is in the sig path between DI and power amp/phones - its shown in the block diag as being a mixer stage for EQ out/Di and Aux In

 

Try a quick lowish-level 'sound check' with a known good signal into Aux In and see if that is also silent (with Master set to 1/3, say?))

 

Edited September 6, 2023 by sandy_r

[neepheid]

It's not the combo, it's the extension cab - I found this rattling around inside.  It's supposed to be connected to the tweeters, whoops!  I'm thinking if this happened during the gig, that might have annoyed the amp into going into protection mode.  The legs are broken off, I've ordered a replacement.  Then we'll see if I cooked the tweeters...

 

Edited September 7, 2023 by neepheid

[sandy_r]

blimey - that's unusual for both legs to separate from that sort of resistor!  If the legs were also unsoldered (ie. both completely loose & free)  there must have been some serious heat thro the res to desolder itself - it's rated at 20W, so it would probably handle a good proportion more before failing, so could have been at least 30W, say

 

Sounds like something has shorted in the extension cab - it could still be something in the crossover like a coil or cap - the tweeter seems an unlikely culprit if it's piezo -  possible if its moving coil, but would have expected the coil to fail open- rather than short-cct

 

The amp protection should have kicked in while this was happening but unless a fuse blew as well it should be working ok now. The fact that you heard hissy signal thro phones connected to spkr o/p suggests no fuse blew in main amp section (if such a fuse exists) and the continued operation of the pre (up to the DI) shows the main fuse didn't blow

 

Presumably the total speaker load on the amp was no less than 4 ohm, otherwise the protection would have kicked in

 

If you were only using the extension cab (ie Redsubs own spkr disconnected) then a serious failure in the extension could have damaged the power amp section (but doesn't seem to explain the loss of phones out?)

 

Sorry to hear that a trusty amp is now poorly - hope it can be recovered to full health again

 

 

[Edit] of course the crossover res fault could have happened at some other time - if there are no other issues inside the extension (component/wiring shorts, driver failures, etc) then that could be result of poor production/vibration issues.  In which case, you're back to a possible failure in the Redbus (maybe only around the Muting circuitry - or even the power protection sensing, itself)

 

Edited September 7, 2023 by sandy_r

[neepheid]

For clarity, the cab is homemade (not by me) from a kit (Bill Fitzmaurice BFM Omni 10.5) and the resistor was not glued down or anything and the whole thing is not soldered (it's joined up by connector blocks) so I reckon vibration eventually took its toll - the legs were left sticking out of the connector blocks.

 

Amp seems fine now, by itself it's happy to go loud.  The cab was working too even with the missing crossover, must have been a blip when the resistor gave up.

 

I've ordered a replacement resistor, and I'll be glueing the bugger down this time!

Edited September 7, 2023 by neepheid

[sandy_r]

Phew - glad to hear all to be sorted!

 

cheers