10. October, 2012
Peavey 5150 / 6505 series mods
About the different models:
The Peavey 5150 should need no introduction.
The 5150II is a 5150 with an improved clean channel, and a modified distortion channel. It also has a different power supply and a few changes in the power section. You can’t make a 5150 sound like a 5150II or vice versa without severe modification, but you can get them a bit closer by some simple mods.
Later, the 5150 was relaunched as the 6505, and the 5150II as the 6505+. They made no changes to the circuit at this point. If a 5150 sounds different from a 6505 it’s due to different tubes, or the age of the components, not a change in design.
The 5150 2×12 combo is different from both the 5150 and the 5150II. Tone-wise it’s said to be somewhere between the two, but I don’t know this circuit.
The 6505+ 112 combo has a preamp nearly identical to the 5150II, but a new fx loop and power amp.
Make your 5150II sound more like the original 5105
![]() This mod will make changes to the preamp section to make the ultra channel of your 5150II match the specs of the original 5150. This without affecting the clean/crunch channels. Your amp will be be growlier, more organic, more gainy and get a chunkier attack, but it will also become less tight. It will not sound 100% like the 5150, as there are some differences in the fx loop / power amp stage as well, but it will take it in the right direction. |
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This mod is also applicable to the 6505+ 112 combo, but the component names differ.
5150II head: 6505+ 112 combo: |
Mod the 5150/6505 lead channel to match the specs of the 5150II/6505+
You will get a more twangy top end, more fizz, not as much of a raw growl to it, and a more processed feel/sound overall. If this is what you want, do the opposite of what’s stated above.
Bias Mods:
6505+ 112:
it is possible. I recently got an email from a man called Brian Mangan, saying that you can adjust the bias of this amplifier by altering the value of R14. I have not taken the time to check the schematic or try it myself yet.
EQ Mods:
OPTION1: Shift the mid frequency downward This is a very simple mod which will move the focus point of the MID band to a lower frequency. 5150/5150II: 6505+ 112: OPTION2: Make the mid frequency sweepable 5150: 6505+ 112: |
Other preamp mods:
I found these mods in the Rig-Talk forum, and they were originally posted by Mark Cameron. They are designed for the original 5150, and may or may not work well with the 5150II or combo versions:
V5B(middle preamp tube): add 10pf silver mica cap to pins 7 and 8. This will remove hiss, make the gain less fizzy, make the high mids clearer and improve clarity in chords. between pins 6 and 7 it’s even more efficient, but will also darken the amp a lot.
R9: piggyback a resistor on top of the 1 meg resistor. 120k is a good starting point. You can try out 68k, 100k, 120k, 150k, etc. Lower value means tighter amp, but if you go too low, the amp will be choked out.
C26: cut one leg for less bottom end on the rhythm channel
C15: bypass cap for better “feel”
R22: bypass for better dynamics and clearer picking response
I tried tinkering with R15 and using Marshall values, but it took too much away from the original sound. The 39k is the SLO value as well.
Power amp mods:
replace screen resistors (with 1k 5W)
add choke somewhere. I have to study these further. To be continued.
Credits:
I didn’t figure all of this out by myself. I’ve gathered some of this information from forum threads, and here are some of the sources:
http://www.mrbobo.com/music_5150_mods.htm (5150 bias mod and tone stack mod1)
http://www.ultimatemetal.com/forum/backline/596150-5150-mod-thread.html (EQ mod 2 + etc)
combo has a preamp nearly identical to the 5150II, but a different fx loop and power amp.