thinking about a new Carvin X100B, but modding it.

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singtall

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a friend sent me this link:

https://www.youtube.com/watch?v=xWHhJ...e=results_main

that's my kind of tone for sure. i feel GAS starting up again.

i played through one of these heads back in 1990 for one concert (a sound company provided the backline) and i was impressed that the clean was so Fenderesque and the crunch was so Marshall hot rodded JCM800, then you could press a button and really boost the gain to the point where a distortion/overdrive pedal was not needed. even the reverb was super lush, and the channel switching quick and quiet.

the only thing that ever kept me from buying one of these was that they stopped making them for awhile (when i had the money to buy one). when i revisited the thought of buying another x100b head, i ended up getting the V3 thinking that it had more features and was a better choice. the V3 didn't work out for me, so i sold it. now i'm looking at the x100b again, but one thing i would just have to modify to be happy is the gain boost switch....it's not footswitchable. i was thinking that i could maybe do some type of JFET switching and use the reverb footswitch for the gain boost (instead of switching reverb on/off). i still have the solder skills, but I would need some help with the "how" to redo that circuit (since i've been out of electronics for too many years now).

any ideas? http://www.carvinmuseum.com/pdf/amps...nschematic.pdf

looks like the lead drive is turned on by a simple SPDT switch, while the reverb is switched via transistor. i was hoping this could be done without adding any relays. maybe two JFETS? but would that add noise to a high gain signal path?
 
not sure i can help you.. but you're right about it being a bummer that you can't go from the drive channel to the lead boost via footswitch. i have an x-60 head that i use quite a bit.. but i set it up with pedals in front on the rhythm channel and use the lead drive engaged for soloing. it works pretty well.. for me anyway.
couldn't you just use a clean boost of some sort to get the extra 20db's? or an eq in the loop.. which is switchable? it sounds like you want to get the tones from the amp and not boxes.. though it takes pedals well.. imo. ymmv.
 
I'm not sure how close the new one is to the x100b they made back in the late 80's early 90's. I had one with the fuzzy grey covering and it was a really good amp. Plenty of gain, awesome clean and really simple to dial in.

Maybe you can find a used one. I seem to remember that the effects button on the foot switch acted as a boost if there was nothing in the loop.

Scott
 
the loop does act as a boost if nothing is plugged into it.. but it doesn't add the 20db's that i think the op wants. imho it didn't do much for me for what i needed.. so i went the other route.
not sure what the new ones do.
the reason i mentioned the eq in the loop is because you can set the level and have a lot of tone shaping at your disposal and it's switchable via the loop. i saw a yt demo where a guy did that on one of the newer models and it sounded really good.. imho.
 
yeah, i'm trying to get all the gain from the amp. with the gain boost engaged it has tons of gain...i guess i could just roll back my guitar volume like i did back in 1990 when i used one of those grey carpet covered half stacks. but it sure would be nice to easily switch the gain on and make the amp a 3 channel amp.

if i can't get the mod done easily i guess i will resort to using a dirt pedal on the clean channel and kick in the full blown gain channel only for leads. not sure what pedal would get even close to the same sound as the crunch channel though....maybe a blackstar pedal?

or maybe just leave the gain switch off and boost it with a Boss SD-1 for leads like i would with a JCM800?
 
it seems like all those options are viable. do your homework.. then test drive a few of the options if you decide to get it. they are nice amps and under-rated imho.
 
just wanted to add that the x 60 i have is one of the first versions that carvin came out with originally. it's got the black tolex and 6L6's. it doesn't have the hotrodded 800 el 34 sound that folks were looking for.. which is why they made changes to the later versions. it's also why i put the pedals in front.
 
trade completed! i got the carpet covered X100b head with two 4-12" top slant cabinets. i parted with two of my least favorite guitars on the trade. value wise, it was a good fair trade to me.

when i tested the amp, it wasn't without some issues though. first the good stuff:

1) the clean channel is glorious! one of the best clean channels that i have every heard....and it takes pedals really well. i could stop here and say the amp is well worth the money just for the clean channel alone.

2) the distortion channel had more snarf than bite....bummer. it sounds like a huge fat fuzz pedal without the top in fizz. not my cup of tea for sure, and not what the amp is supposed to sound like.

the guy says that the tubes are all about 8 months old and haven't been used much.....hmmm, hard to believe but i'll give him the benefit of the doubt.

what i found wrong with it? the distortion sounds like the front end pre-gain shaping circuit is missing. the lows should drop off some before the distortion turns it into mush. that ain't happening. the clean channel begins to break up after 2....way too early.

i'm going to take the head apart now and clean every pot and look it over, hopefully it's something minor.
 
i wonder if carvin tech support might help shed some light on the problem? the few times i've had to deal with them they have been very supportive of their products and seem all too happy to help.
 
those things were hit and miss. iv played a few 60 watters that were great... I had a crummy one in 88.. sucked big time.
 
i wonder if the op forgot that the eq is active? if you don't start with the tone controls on five and the graphic set flat and try to dial it in like a regular amp.. it's going to suck for sure.
 
the innards were pristine clean....no mods. the pots were really dirty, so were the jacks. it appears i had two issues:

1) the effects loop jacks were filthy from non use and not letting much signal through. the same with the input jacks.

2) the inverter tube was weak/bad. i changed out all 12ax7 tubes.

here is what i think i found out about my other complaints so far; the 25 watt mode basically starves the inverter tube, making it distort at anything over bedroom volumes. 50 watt mode was the same thing, louder, but not enough to compete with a drummer. full mode was super loud and clear for cleans....i will pretty much keep it there.

the high gain channel is clearer sounding thanks to the new tubes. the only "issue" i can see if that the notes compress with the gain over about 7 in hot-rod mode. lead and squealies are great, but chords drop in volume and come back up like a compressor cranked up too much. on thing really cool is that the even harmonics just jump out and you can get that great feedback and low volumes.

i found some mod sites and i may tinker with it while a little. so far, i think i got a great deal.
 
glad it was something simple. :) that tone description sounds about right. the power tubes are biased on the cold side when they come from the factory.
enjoy your new amp and have fun tweaking. :)
 
i'm thinking about gutting the gain section and doing something different, any suggestions? i may have to send this to some amp wizard that can mod it.
 
jerryp at fja mods. he's a regular contributor here and does some standard mods for x series amps. he also does custom mods if you need it. he's listed in the manufacturer's section here. he's also got a few yt vids you can check out.
 
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