Fix my broke Carvin BX1500

[DJ Bebop]

I found this explanation on the TB from 2016. Hopefully this helps others out as well. I would change out the tube for a more warmer sounding one.

"I recently acquired the schematic for my BX1500 and discovered that the tube is after the amp 1 and 2 controls just before the poweramps. This was proved out when I turned down the master and maxed the amp 1 and 2 controls and sure enough I could finally hear the tube. You still need to give as much pre-gain as you can to hear the tube warmth come out. If you use the effects loop, you can boost the signal before the tube."

You know, now that you mention it. I do remember reading in their promotional literature about the power amps being driving by a tube drive.

 

[jeff7bass]

I do not have this amp but the B1000 also with a tube. I had to put my Radial Bassbone on full and then then Boost level to 75% and then on the Carvin the drive was on max, before I heard a mild distortion. It was actually quite nice for that kind of tone but the noise floor went up.

I really liked the DRIVE knob on my BX1200 but it wasn't a pre-amp tube drive, it was some kind of emulation. Regardless it added a distinction to my notes that was pleasant to my ears as well as sound guys and musician friends.

 

[ricksvintage]

Old thread for sure, but here's the fix in MY current situation for when only 1 of the power amps are working, regardless of the X over position- I could only hear slight volume from the dead side so my intuition said...

Replace the 12AX7!

Replaced the original Chinese tube with a decent JJ, and VOILA! It's loike fookin' magic mate , now it sounds better than ever!
Remember, a 12ax7 has TWO sides( it's a DUAL triode) and it's pretty common for 1 side to fail after time.
You can thank me later

 

[Element Zero]

 

[DJ Bebop]

Old thread for sure, but here's the fix in MY current situation for when only 1 of the power amps are working, regardless of the X over position- I could only hear slight volume from the dead side so my intuition said...

Replace the 12AX7!

Replaced the original Chinese tube with a decent JJ, and VOILA! It's loike fookin' magic mate , now it sounds better than ever!
Remember, a 12ax7 has TWO sides( it's a DUAL triode) and it's pretty common for 1 side to fail after time.
You can thank me later

View attachment 5369220 View attachment 5369221

That kinda make sense as I remember the tube in these are after the preamp but before the power amp.

Not like most hybrid amps that have a tube in the preamp section. So each side of the tube drives one side of the stereo power amp section?

In their literature at the time, they described the amps as having a tube driven power amp section.

 

[KevInDaBassment]

Ehhh, mine (BX500) failed not long after the warranty period and the situation was as followed...

- Used it as an amp head for a month or two (going straight in)
- Shortly thereafter, used it as a power amp only, bypassing the preamp
- Never had master volume on it past 11 o'clock
- Was insanely gentle with how much signal came from my VT Bass Deluxe into the Carvin BX500

- All the sudden one day...starts popping on and off while the power light blinks
- Checked cables and outlet, all good, but amp is still popping
- Open it up and there's barely a speck of dust in there. Reseated cables, I also have an IT background so ribbon cables and such don't scare me...no dice

- Called up Customer Support and was told I could throw down several hundred $$'s for repair, just buy another one, or go pound sand.


I've never bought another Carvin product since that day, and to my recollection I've only had one other amp fail on me (a Peavey VB2 where I was the 2nd owner of it), so I don't believe I've got a reputation of being rough with my amps. Interesting to see other people having similar experiences with these amps. No sense beating a corpse though...pretty sure these amps are discontinued at this point.

 

[Core Creek]

My red BX700 has been going strong since I got it in a trade about a year ago. The previous owner said he had his tech solder the ribbon joints, or something like that…. I haven’t looked but I suspect the ribbon connector was removed and each cable was soldered together to eliminate any weak points.

Nonetheless, I love the amp. I also have a BX1600 but dare I say it’s too much power for most gigs.

 

[DJ Bebop]

Still nursing my BX 1500 along. Wiggling the cables a bit on occasions to get it going. Works fine after that.

I've been ignoring it for my little Mesa rig though.