6505/5150 choke/bias mod

[ACHIEVEIT]

Hi guys, a couple of hours ago i finished modding my peavey 6505 and i am really excited and wanted to share! I don't post regularly as i don't have many things to contribute - i am mostly reading. This was my first amp mod.

Anyway, the mods are:
-Replaced screen resistors with 1K 5W for safety reasons
-Installed bias circuit
-Installed choke (Hammond - ~100Ohm, 150mA, 10H, i think it is called 193G?). Thanks PaoloJM for the suggestion.
-Relocated the standby switch to avoid hearing a 'spike', due to the choke's lower resistance (the original resistor was 400 Ohm)

It feels like a different amp! I cannot understand why some people on the internet say the bias mod or the choke mod don't affect the sound much. It sounded like night and day to me. By the way i biased around 32mA. I don't know, maybe it is because i did both mods at the same time but the difference is really apparent even at low volumes. My excitement led me to record a clip with my iphone. The mic isn't very good to begin with (but it is far better than most cell phones) and youtube really compressed the sound, so i don't know if it is really representative. But i post it in case you want to hear it anyway.

What i feel has changed is the pick attack. It feels quite different (and better to me). You might be able to notice it in the video. Also, the cleans have improved dramatically (although in the video i was playing a les paul and had the amp set to a nice distortion sound) - plug in a strat and you have decent/nice cleans and excellent distortion. Also, thank god, the fizziness has disappeared! The bottom end is tighter and the gain more useable. It also, generally sounds warmer without losing its edge - it think that shows in the video. Also, the eq feels more responsive.

Please excuse the playing. I really hadn't thought about recording a clip so i wasn't prepared. Also, i never took the time to learn these songs right, so what you hear is by ear/memory. I recorded the clip pretty low on volume because it was around 10 o'clock in the evening here and didn't want to upset the neighbors. I had cranked it earlier though and it sounds great.

Guitar is a Tokai Love Rock LS135SEB with Seymour Duncan Alnico II Pro's. I was plugged in the high input. The gain on the lead channel was on 4 (scale 0-10). The master around 1. No pedals, effects, boosters etc. Just guitar, cord, amp. Cab is a Marshall TSLC212 w/ 1xVintage 30 and 1xG12H Heritage. Tubes are EHX 12AX7s and 6L6s.

http://www.youtube.com/watch?v=zvxoKAbGqqo

Thanks for reading/listening!

[axeman]

Can you please tell me how to do the mod on a EVH 5150 and place a pic of the bias mod.


Thanks

Art

[ACHIEVEIT]

Hi there,

the bias mod is very well documented. This is the instruction set i used as well. It contains detailed pictures and text!

http://www.blueguitar.org/new/schem/pea ... as_mod.pdf

If i can be of further help let me know! John

[ACHIEVEIT]

Here is another video, this time with a strat (stock Fender Classic Player 60s) - single coil pickups all the way. The clean tones are mostly neck+middle (2nd position) and the distorted ones are mostly just bridge (5th position). Again please don't mind the playing (and the tuning of the guitar..).

Unfortunately, the way i placed the cell phone managed to destroy the recording a bit. It is clipping at some times and because it was exactly opposite of the cab, the sound comes somewhat thinner and more shrill than it really was. But what i wanted to show was that the amp has become really versatile. I think an HSS guitar would be the best as you could have very good cleans combined with huge distortion.

Again, no effects were used - just guitar, cord, amp. This time i was plugged into the low input. The clean channel was set around 2 on both gain and volume. It was clean clean - the distortion you hear some times comes from the clipping of the mic! The lead channel was about 8 on gain and 1 on volume. Near the end of the video i lowered the gain to about 4. Hope you guys like it!

http://www.youtube.com/watch?v=6EovevPVpQ8

Thanks

[axeman]

I have a problem with my amp rite now, the output level is very low. When I connect my guitar to the send or return the level becomes louder with clean tone, I've cleaned the pots and jacks, all screen resistors are good. I also installed new power and preamp tubes. Do you know what else I can check?

Thanks

Art

[ACHIEVEIT]

Sorry, i don't know the technical stuff much. But from your description i would suspect either a problematic preamp tube or a loose connector between the preamp and the power amp section. The speculation comes from the fact that your pa seems to work fine (when you connect the guitar in the return) but when you plug it in front it does not.

BTW when you say it becomes 'louder' is it simply louder than in front or deafening? If the pa works ok it should be the 2nd, as there is no effects loop pot and the post gain pots don't affect the effects level. That means that if you stick the guitar in the return, it is like running the amp on full volume. I hope i haven't said anything stupid!

[axeman]

Yes, it becomes louder pluging into the Fx Loop compared to the front.

[Bradley Walker]

(the original resistor was 400 Ohm)

Can someone show me where this is located?