5150 mods... revealed w/ pictures

This mod is SICK! I bought my 5150 to replace my DSL 100 because I was fighting an intermittent crackling in the preamp (which I think I finally fixed). The 5150 had all the power and wallop, but no jangly sweet tone. Profoundly improved after the mods. I played it with the bias mod first @ 38ma and it was better, but absolutely night and day with the other mods. I went with a 220K ohm resistor at R9. Gonna play this week with the band for the first time since modding. I think this thing may just take the #1 spot in my rig now! Thanks Psychodave and everyone else!!!
 
Are all the resistor/cap changes mentioned in this post applicable to the 5150II? I would like to change up the sterile tone this head has and make it more focused with a tighter gain. The sound clips really seem to make these heads come alive and on the same level as their counterparts that are way more expensive. Thanks for any help. Bob
 
Played my first practice session with the new improved 5150. It is WAY better than it was before, but I must admit I still think the DSL owns it. Need more time with it to dial it in or perhaps I just can't get used to 6L6s. I'll post up any further changes or discoveries.
 
Stymie13":1smq7cq4 said:
Played my first practice session with the new improved 5150. It is WAY better than it was before, but I must admit I still think the DSL owns it. Need more time with it to dial it in or perhaps I just can't get used to 6L6s. I'll post up any further changes or discoveries.
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It's not the 6L6 you are hearing, the power tubes really don't have a qualitative effect on the sound of an amp, but the bias range that the power amp runs on does. The preamp voicing is much different than the DSL, this is what you are hearing.
 
Yeah, you're probably right. I'm just partial to that sweet, jangly upper mid Marshall voicing. I just listened to a track from Thursday's session and the 5150 sounds super bad ass! It compliments our other guitarists DSL really well. Besides, can't have two DSLs in the same band right?
 
I know this is an older thread but thank you for the info(pics) and for mark giving the ok. I did the 10pf mod (already did the bias mod) and i love it. My poor amps never gotten such a beating
 
I just moved the cap from anode to grid (pins 6 and 7) and it makes a much bigger difference there. I have to play with it a bit more to see if I like the amp better this way or not. It definitely killed a load of fizz, but I have to crank the presence much higher than I did before or it's too dark. The lead channel is much improved, but the rhythm channel has taken a hit for clarity at similar settings. It is different in crunch mode, but I use the rhythm channel for a clean sound. Actually the clean sound is quite good now, but I like to play old Hendrix and Clapton stuff on a loud clean channel sometimes and first impression is that it's just a bit too dark to get the right kind of spank. I know that my 5150 was a fizzfest earlier, so I am probably not used to hearing it sound this smooth LOLOL. More time will be needed to judge though. I am actually quite surprised at how much effect this has had on the amp's sound, though it still has that character 5150 grind.

Great mod idea Mike and Dave, thanks for sharing :rock:
 
psychodave":20tgk39f said:
I agree that going to pins 6 & 7 make it brown, but I got over the fact that you need to turn up the presence. I didn't notice any issues with the rhythm channel either. The few mods in my first post make the 5150 a LOT better...while keeping the 5150 tone that we love ;)
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Yepp, I get it now. I just got a new set of power tubes in today and it seems that they are both brighter AND less fizzy. As a result, I much prefer the 6 to 7 cap mod now :D
 
I finally did the 10pf Silver Mica mod. I've had it sitting around for months, but was too afraid to do it as I've never used a soldering iron before in my life. I finally said "fuck it" and went ahead and did it and I'm pretty happy with the results. It's not a huge difference or anything, but the low end definitely feels tighter and less boomy. I can actually crank the low end all the way to 10 now and it stays together, whereas before, after about 8 it would turn to mush. Thanks again for posting these :)

I did it as shown in the pic. I assume that's 7 and 8, and if I wanted to try 6 and 7, I would just move it up one, so it's the two pins in the top right corner?
 
psychodave":1gnth8wh said:
madrigal77":1gnth8wh said:
Bump!! Also, can someone show me in the pic where C15 is, and how do I "bypass" it?
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Regarding pins 6 & 7...yes, just move the cap up one more spot. Look at the bottom right side of the back of the tube socket and go counter-clockwise from #9 ;)

The first pic shows C15. Look to the right side of the pic at the "red" cap. You should notice a wire running across the bottom of the cap...thus bypassing it. ;)
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Cool, thanks a lot. I couldn't manage to jam a wire under c15, so I gave up :LOL: :LOL: . Still loving the 10pf mod though :thumbsup:
 
i know this thread is super old, but i just wanted to let everyone know that i did the 10pf cap mod and also the r9 resistor mod to my 5150 II, and they have the same affect as on the original 5150. really helps the tone out quite a bit.

so those two mods i can verify work on a 6505+/5150II
 
MYLILSS":1tck3ojb said:
i know this thread is super old, but i just wanted to let everyone know that i did the 10pf cap mod and also the r9 resistor mod to my 5150 II, and they have the same affect as on the original 5150. really helps the tone out quite a bit.

so those two mods i can verify work on a 6505+/5150II
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Cool. Trying it tonight.
thanks
 
R9: piggyback a resistor on top of the 1 meg resistor. I used a 120k based on feel. You can try out 68k, 100k, 120k, 150k, etc. This tightened up the map a lot! now is this jsut a 120 k resistor.. or does it have any specific watts to it like some do.. or does it matter.. and has anyone tried the clipping C19 for less frizziness??? thanks i am going to do these mods and bias mod but need questions answered first
 
on R9 felt 120k, even 220k was taking away too much from the original tone. I liked 470k minimum................and then my amp died :confused: .... but i dont think thats related to these mods. I bought mine super used and beat up and it just isn't like how a 5150 should be.... :aww:
 
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