Carvin X50B - best amp ever?

[1big1]

hard to say what that noise is. i'd try deoxit on the pots.. switches.. jacks and maybe the tube sockets as well. if i were going to tear it that far apart i'd also look for cold solder joints or any loose wires and possible discoloration of components or burn spots as well as checking and cleaning grounding points. give it a good cleaning and visual inspection.. put it back together and see if that solves the problem. does it do the same thing on the number one input?
i'd also re-tube at the same time. i'd put in a pair of matched power tubes for starters. mismatched tube varieties can yield some interesting results. (i have yet to try that) however the folks that like doing that do match the tubes for current draw.
i usually take a few pictures and clearly mark or label stuff so i know how it goes back together when i tear something apart and clean the crap out of it.

 

[simon_d]

Yep all good advice. I did some tube troubleshooting and seem to have reduced the hum. V1 (I assume it's V1, the tube closest to the input jacks) was most problematic and needed a low microphony tube. I assume the PI is the tube closest to the power tubes? Put the Brimar there. One of the mullards was a bit weak, but I had another to replace it. Sounds much better. I have a matched quad of winged C's so I'm running 2 matched power tubes now as well. Deoxited the switches (the power scaling switch notches were a bit indistinct before) but not checked in the amp for cold joints. I did a quick visual when I got the amp for any bulging caps or burn marks - all was very clean in there. Should have taken a snap while it was out.

I reckon another good clean up and replacement smoothing caps, and bias pot will sort it out.

 

[King Crimson]

Well of course it would be impossible to really claim that as it's all subjective, I've never played one before but I have to say I'm blown away by this amp! If you think they are just for 80s hair metal think again - blues and clean tones are stunning too. Responds to you playing with articulation and definition (this is IMO the most important quality for an amp:

Brilliant, 20 posts, never played the amp but you're blown away by it, know how it responds, but you've never played the amp.

Again, Brilliant! You take the absurd cake for the post of the day.

 

[1big1]

Yep all good advice. I did some tube troubleshooting and seem to have reduced the hum. V1 (I assume it's V1, the tube closest to the input jacks) was most problematic and needed a low microphony tube. I assume the PI is the tube closest to the power tubes? Put the Brimar there. One of the mullards was a bit weak, but I had another to replace it. Sounds much better. I have a matched quad of winged C's so I'm running 2 matched power tubes now as well. Deoxited the switches (the power scaling switch notches were a bit indistinct before) but not checked in the amp for cold joints. I did a quick visual when I got the amp for any bulging caps or burn marks - all was very clean in there. Should have taken a snap while it was out.

I reckon another good clean up and replacement smoothing caps, and bias pot will sort it out.

yup v-1 is closest to the inputs and the pi is nearest the power tubes. on my amp the pi is right between and forward of the power tubes. i forget exactly what gets dumped into which triode on the 12ax7's.. but i believe the reverb and loop are not run into the tube preamp section. i think those are ic's.
the other thing you find with these amps is that the master volume control doesn't affect the rhythm channel.. like it would on a typical amp. i just set the rhythm channel volume and use the master to set the lead channel volume and add the desired level of drive. i don't know why they labeled it master. maybe they couldn't fit lead volume on the face plate?
anyway.. it seems like you've got it pretty well under control and should be able to put some hours on it.

 

[simon_d]

Well of course it would be impossible to really claim that as it's all subjective, I've never played one before but I have to say I'm blown away by this amp! If you think they are just for 80s hair metal think again - blues and clean tones are stunning too. Responds to you playing with articulation and definition (this is IMO the most important quality for an amp:

Brilliant, 20 posts, never played the amp but you're blown away by it, know how it responds, but you've never played the amp.

Again, Brilliant! You take the absurd cake for the post of the day.

Try reading my post again. Out loud. Stressing the word 'BEFORE' in the first sentence.

 

[simon_d]

yup v-1 is closest to the inputs and the pi is nearest the power tubes. on my amp the pi is right between and forward of the power tubes. i forget exactly what gets dumped into which triode on the 12ax7's.. but i believe the reverb and loop are not run into the tube preamp section. i think those are ic's.
the other thing you find with these amps is that the master volume control doesn't affect the rhythm channel.. like it would on a typical amp. i just set the rhythm channel volume and use the master to set the lead channel volume and add the desired level of drive. i don't know why they labeled it master. maybe they couldn't fit lead volume on the face plate?
anyway.. it seems like you've got it pretty well under control and should be able to put some hours on it.

Yeah, I think the reissues have a master for both channels now - they have 9 knobs instead of 8 anyway, and I like the mini toggles for channel switching and boost. I almost bought a mint one off ebay the other day, only 1 bid and it went for about $450/£275! Wish I had bid now. But I don't find a lack of a MV an issue on the old ones since on full power mode the clean is clean all the way up, so no need for one

The hum is still there I now notice, it's just quieter. I think there's maybe something up with my house power supply, as its also on other amps when I crank them up too, and my pedal board makes it worse (maybe a ground loop? That could be a can of worms though ).

But back to playing this thing now - it sounds killer. Loving the SD1 into it at the mo, really dark and smooth solo tones.

 

[1big1]

i never found the lack of true master a draw back. like you said.. clean all the way up. iirc the first triode on v-1 is for the number two input. input number one uses both triodes. v-2 uses one triode for lead and the second triode for pull high lead. at least i think that's the way it's laid out on the old ones.
i may throw that tung sol in v-1 anyway. either i'll like what it does for cleans.. or i won't. i'm just trying to picture in my head what it sounds like now vs. what i'd like it to sound like when i'm done.
as for k.c.? i don't feed the trolls.

 

[simon_d]

Thanks for the info on the triode usage in the X amps. Never had a tung Sol myself. If it's tending towards bright and fizzy maybe not a good option for V1. I thought that some of the distortion in the X100/50b was from transistors or is that untrue? I'm no purest so I don't care as long as it feels good.

Trolls, yeah I should know better

 

[1big1]

the tung sol i've got is a pull i picked up from somewhere. it's a 12ax7 but it's lower in gain and very smooth. i'd describe it as sounding like an xmas tree with a spike of treble at the top.. if that makes sense. it may work well with pedals because of the lower gain and tapered treble. i've got a couple of other tubes i can try for pre's.. but i'll run with that one first.. on a hunch.
could be some of the distortion is from transistors.. but that isn't a big deal for me either if it feels good. and it does.

 

[1big1]

we set up the p.a. we're going to be using for an outdoor gig. we wanted it to sound full.. so i ran out of the built in xlr in the back of the head into a board channel. that was what was too bright. iirc it's only an out for the preamp. we made a rough recording and it was nothing but preamp. put an sm57 on the cab. problem solved.. except now i can really hear the missing mids with 75's.
i actually dialed the mids back to about 4 to tighten up the treble and bass balance with the 75's. i was trying to play to the response the speaker seems to like best. i may scoop that just a hair more yet. it seems to me that too much mids with a 75 masks the treble and bass balance and it tightens as i dial the mids back. i also dialed back the bass to 4 because of the proximity effect of the sm57.. and left the treble and presence where they were. still gotta tweak the lead tone a bit too. i'll probably use the 150 hz fader and try to add a bit more body to my lead tone. you should try this amp with a tele sometime.