5150 - Recent Mods & Opinions ???

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SLOgriff

SLOgriff

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I installed the Bias-Pot (ala FJA-Mods type), the 10pf, and clipped one leg on C26.

I installed matched quad of =C= 6L6's. First off, the Red/Lead channel is just awesome now! Very throaty, tighter, and just feels great. The Rhythm channel was too dark compared to the Lead channel so I opened it back up and clipped a leg off of C26 (reduces some low end off Rhythm channel). This helped balance the overall tone between the two channels, BUT the Rhythm channel just seems "ok" now(either Crunch or Clean mode). I can't tell if its because the Lead channel sounds so good that it makes the Rhythm side not so good....or did something change the character of the Rhythm channel as well??? I can't put my finger on it, but its missing something...maybe upper mids or gain.

Anyone else notice this, or is there another modification to bring the Rhythm side closer to the "new" Lead tone??


Bryan
 
How is the rhythm channel sound without the crunch if you try to use it clean. Does the less low end improve the clean tone?
 
chumbucket":uhp103sc said:
How is the rhythm channel sound without the crunch if you try to use it clean. Does the less low end improve the clean tone?
Click to expand...

The only improvement is a little less low end which helps to blend better with the Lead channel. I don't think C26 effects anything else and seems worth it to remove the "darkness". Either Crunch mode or Clean just seems to be missing something. Just was curious if anyone else experienced this with the Rhythm side after doing the 10pf mod.
 
This thing died pretty quick.... Did anyone else notice a "negative" change in the Rhythm channel after the 10pf cap mod?? :confused:
 
I did the 10pf and the rhythm channel is bland but I don't have a real good frame of reference. I wasn't real familiar with the natural sound of the amp before I started modding it. I'm using it for clean and not crunch. I have the post cranked up full on the rhythm channel and the pre at around 2-3. I also keep the lead channel gain low for a good crunch tone and then boost for leads. Poor man's three channel.

I need to cut the leg on c26 I think. The rhythm channel seems a little too bassy. I'm waiting until I get some new power tubes so I can do everything at once.
 
chumbucket":ls50jd79 said:
I did the 10pf and the rhythm channel is bland but I don't have a real good frame of reference. I wasn't real familiar with the natural sound of the amp before I started modding it. I'm using it for clean and not crunch. I have the post cranked up full on the rhythm channel and the pre at around 2-3. I also keep the lead channel gain low for a good crunch tone and then boost for leads. Poor man's three channel.

I need to cut the leg on c26 I think. The rhythm channel seems a little too bassy. I'm waiting until I get some new power tubes so I can do everything at once.
Click to expand...

Yeah, the Rhythm side is definately "darker" than the Lead. Bland is a fare term...it's just missing something. I immediately took my amp apart and clipped C26 (after I did all the other mods) and it does help to remove some of the low end. It's more subtle and not a drastic reduction so I wouldn't be too hesitant or concerned.

Still surprised that no one else has chimed in.
 
chum

where is c26 my board is old, not labled on either side.
do you happen to have pics laying around of that particular c26 mod?
 
I Strapped C15 and bridged the V2B Grid-Cathode with a 10pf. I seldom play the Crunch channel. The Lead Channel now can be dialed tight but still has that massive feel.
 
Bro maybe post this over at the FJA section. I have my 5150II at Jerry's right now for the metal mod. Can't wait to get it back.

Jim
 
will do! thanks man!

i was hoping i could lure psychodave back in....apparently he's just gone from the internet, at least under that moniker. it sux, i always liked reading his posts for info...

let me know when you get it back, we'll have a mini fest..you're over in the south side area right? im in ross township. we can compare the two amps..by then, my tourmaster should be up and running again, the new PT is in the mail. i have a thd univalve too...it's an awesome lil' class A amp that gets REALLY loud and allows you to check out different preamp tubes too.
 
sled":2301q1xg said:
I Strapped C15 and bridged the V2B Grid-Cathode with a 10pf. I seldom play the Crunch channel. The Lead Channel now can be dialed tight but still has that massive feel.
Click to expand...
now what is this??? c15 isnt that the better feel mod dave puts it??? how does this make the amp sound different???.. i did everthing except that mod.. and amp sounds tighter, better actually.. im wandering if there are another mods floating around out there....
 
you bypass c15 by either clipping it or putting a wire from leg to leg.

also, this is the thread psychodave posted and got pretty in-depth.
viewtopic.php?f=3&t=80183&hilit=5150+mods

imho, c15 is something you gotta do to feel it, viewtopic.php?f=3&t=105297 refer to that post where i explained it a bit. i love it, though, as stated, i had to pull my board to unsolder as c15 was really tight against it and loosen it so i can then attach a wire to bypass it. but i put the wire on the side you can access easily without pulling the board, so i can undo it later if need be.

i HAVE to stress though for anyone thinking about modding their amps following anything i've posted DRAIN YOUR CAPS. i made a simple cap drain harness out of 2 pieces of wire, a big fat 28 watt 200 volt resistor, and alligator clips. i soldered the resistor in between the wires and shrink tubed the exposed metal of the wires and resistor. put the alligator clips on each end of the wire. one clip i leave free (this is the one i clip to ground or chassis) the other clip i electrical taped a long chop stick to, so i can poke around in the amp without my fingers and hands being in there. i HAVE to stress this, it's REALLY important, as, even after draining my caps via the power/standby method, some of them are still holding a charge, and there are smaller caps on other parts of the board that you should drain to, as mine were holding some voltage too. it takes little over 5 minutes to make the harness, and less than that to drain the caps every time you're in the amp...just do it, be safe and drive on with the rest of the mission = grail tone!

anyways, stepping down from the soapbox.
in this picture, c15 is circled in red , c26 is circled in black, has been clipped and shrink tubed (thanks chub!)

imma play my amp for another few hours and then do the c26 mod (even if it requires lifting the board again to loosen up those legs too), as i don't love that ch1 has still remained flubby but not as bad as stock...so i want that tightened up too.
 

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The C26 mod (clipping a leg) only removes some of the low-end from the Rhythm channel. The Rhythm channel is darker than the Lead channel.... Doing this mod helps to bring the channels closer...it does NOT make the Rhythm channel any tighter.
 
thanks SLO, i like the premise of it, and will be doing it over the weekend. if i dont like it, easily reversed.

any other mods (other than the bias mod) that i can try/mess around with that you know of?

i dont want to do the bias mod yet(even though i have already wired it up and have it ready to install) because i have no way that i know of to test my plate voltage (and i lack a good grasp of that whole process as of yet) so i've decided that little reward lies down that path, with much risk of fuckery, so, i'll leave that one be for now.

i don't want to install a choke.

i've been trying to dig up info on the ins and outs of replacing the bias resistors, but can't find much info. i don't want to bug jerryFJA cause he's a busy enough dude as it is without me picking his brain incessantly. So, ive been trying to glean as much info as possible by researching on my own.

gotta so though, again, I LOVE this amp stock....i REALLY love the direction i've been able to take it in with a few small tweaks here and there.

MAINLY, i'm looking for more low end/low mid growl and maybe some more upper mid grind.
 
I had a 5150 with an installed choke and it totally killed the tone!! Was horrible!
 
i played my amp for about 4 hours today through the same cabinet....with the mods i already did. currently i have a 49k ohm resistor on r9 and i think that's where its staying. c15 is strapped, and then i did the c26 mod to the rhythm channel, and i gotta say, i LOVE what it did.

thats all! going back to play! i love having another amp i love playing! wondering how my tourmaster and this 5150 will get along together.
 
yeti":2y2k50v3 said:
you bypass c15 by either clipping it or putting a wire from leg to leg.

also, this is the thread psychodave posted and got pretty in-depth.
viewtopic.php?f=3&t=80183&hilit=5150+mods

imho, c15 is something you gotta do to feel it, viewtopic.php?f=3&t=105297 refer to that post where i explained it a bit. i love it, though, as stated, i had to pull my board to unsolder as c15 was really tight against it and loosen it so i can then attach a wire to bypass it. but i put the wire on the side you can access easily without pulling the board, so i can undo it later if need be.

i HAVE to stress though for anyone thinking about modding their amps following anything i've posted DRAIN YOUR CAPS. i made a simple cap drain harness out of 2 pieces of wire, a big fat 28 watt 200 volt resistor, and alligator clips. i soldered the resistor in between the wires and shrink tubed the exposed metal of the wires and resistor. put the alligator clips on each end of the wire. one clip i leave free (this is the one i clip to ground or chassis) the other clip i electrical taped a long chop stick to, so i can poke around in the amp without my fingers and hands being in there. i HAVE to stress this, it's REALLY important, as, even after draining my caps via the power/standby method, some of them are still holding a charge, and there are smaller caps on other parts of the board that you should drain to, as mine were holding some voltage too. it takes little over 5 minutes to make the harness, and less than that to drain the caps every time you're in the amp...just do it, be safe and drive on with the rest of the mission = grail tone!

anyways, stepping down from the soapbox.
in this picture, c15 is circled in red , c26 is circled in black, has been clipped and shrink tubed (thanks chub!)

imma play my amp for another few hours and then do the c26 mod (even if it requires lifting the board again to loosen up those legs too), as i don't love that ch1 has still remained flubby but not as bad as stock...so i want that tightened up too.
Click to expand...

i jsut dont know how to get that little ass wire in between c15.. there is no metal showing.. so what did it actually do when you bypass it??? i know you said it something you have to try yourself.. im jsut wandering if its worth the trouble of taking the board out to loosen it up... you stated that the higher on r9 you went, it lost gain, ive done these mods as well.. the 10pf silver mica and R9.. i piggy backed a 440k to the 1 meg.. when i went lowerthan 120k it seemed to choke the amp out.. it made it tighter but started to choke out the amp.. when i get time im going to try the by pass mod.. on c15.. and im going to lower the r9 resistor again.. i have searched the web for more diy mods but havent came across any.. you think as old as the 5150 is there would be lots of other mods out there.. or someone would look inside there already modded 5150 and reveal the dark secrets.. but the mods ive done im pretty happy with.. c9 and r9 and c26.. c9 contolled the fizzy, r9 tighten it up some, and c26 the rhythm channel is awesome.. i boost the front with a maxon od9 and a boss eqand bbe sonic stomp in the loop.. sounds sick as hell....would like more mods jsut becasue its fun to do. lol
 
it makes it chewier, and by that i mean, more pronounced in the low mids.... and seemed to tighten things up feel wise. it's not a huge difference, but for how i play, i love it. i play with minimally saturated distortion with no boost. it's weird how 49kohm on r9 to me, sounds best with my amp, and it may just be the difference in the resistors themselves (not just the values) that i'm hearing, if thats possible. but, i haven't gone above 223 yet....going to mess around with it tomorrow and play it how it is, then go to like a 660k-ohm resistor on r9...

my recent playing was focused on getting really familiar with the rhythm channel through one specific cab so i could be 100% sure on the change that c26 made when i did it....and, i have to say, those amps shoulda been stock that way. i can play mine above 3 on volume if i wish, and thats where you REALLY notice that one! i have a silver mica on the way to me, so, i'm curious what it'll make the amp sound like once i have my other values set and loving them...i'll probably have to start all over.

the long and short of it though, yes.....it's worth it to pull the board and do the c15.

just make sure you drain the caps. also, mark your wife harnesses to where they go. everything should come off fairly easily, and it's not really a big deal.....just loosen up the legs on c15 with the soldering iron, so you can access them from the top, then, when you get the board back in, you can jumper the legs and if you dont like it, it's removeable.

you'll thank yourself later for doing c15 though.....there's just something about it that i love...there's a certain bwomp to the amp now that it didn't have!
 
yeti":2grwcx3e said:
it makes it chewier, and by that i mean, more pronounced in the low mids.... and seemed to tighten things up feel wise. it's not a huge difference, but for how i play, i love it. i play with minimally saturated distortion with no boost. it's weird how 49kohm on r9 to me, sounds best with my amp, and it may just be the difference in the resistors themselves (not just the values) that i'm hearing, if thats possible. but, i haven't gone above 223 yet....going to mess around with it tomorrow and play it how it is, then go to like a 660k-ohm resistor on r9...

my recent playing was focused on getting really familiar with the rhythm channel through one specific cab so i could be 100% sure on the change that c26 made when i did it....and, i have to say, those amps shoulda been stock that way. i can play mine above 3 on volume if i wish, and thats where you REALLY notice that one! i have a silver mica on the way to me, so, i'm curious what it'll make the amp sound like once i have my other values set and loving them...i'll probably have to start all over.

the long and short of it though, yes.....it's worth it to pull the board and do the c15.

just make sure you drain the caps. also, mark your wife harnesses to where they go. everything should come off fairly easily, and it's not really a big deal.....just loosen up the legs on c15 with the soldering iron, so you can access them from the top, then, when you get the board back in, you can jumper the legs and if you dont like it, it's removeable.

you'll thank yourself later for doing c15 though.....there's just something about it that i love...there's a certain bwomp to the amp now that it didn't have!
Click to expand...
okay well i will try taking the board apart and loosen up the c15.. did you get a chance to use those 470k and 660k yet.. what would happen if you put a 1 meg there.. i know the resistor is a 1 meg that is stock... so would it even change anything???? but thanks for all your help im going to go lower on the resistors and do c15 @morrow for sure.. thansk
 
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