Convert 5150-II lead channel to original 5150 spec.

[hourglass]

I've read here and there that converting the 5150-II lead channel back to the voicing of the original 5150 is not very complicated - possibly a change of just a few resistors.

Does anyone have information on doing this mod?

I've been listening to recordings I made with my original 5150 head and I simply cannot get that sound with the 5150-II I have now. (And yes, I have kicked myself several times now for selling my 5150...)

I did a search on the forum here but I only came up with some bias mod info on these amps.

Thanks!

ryan

[Enzo]

Oh it is about three parts. Try an email to the service department at Peavey and ask them. It does change the4 amp, but having different tubes in the two amps can make as large a difference.

[hourglass]

Originally Posted by Enzo

Oh it is about three parts. Try an email to the service department at Peavey and ask them. It does change the4 amp, but having different tubes in the two amps can make as large a difference.

Cool. Thanks for the reply.

I found a thread over on the Peavey forums which says to replace C2 and C17.

C2 is originally a .001uF cap near V1. Supposed to replace that with a .022uF cap.

C17 is near the Lead Pre pot. It gets replaced with a 470K resistor and a .0022uF cap run parallel. Alternately you could leave it there wire the resistor and a .0015uF cap all parallel.

According to the BOM the .022 is a 630V 10% part. The actual existing cap is a little blue rectangular box. What can I use to replace that? I have a 600V orange drop cap which will fit in the available space.

The existing cap near the lead pre pot is a tiny little blob on axial leads. I have a little yellow and black 400V cap which I could put there. I also have a 1/2-watt 470K resistor.

Are those parts OK to use there or is there something else I should be looking for?

Thanks for the help.

ryan

[Enzo]

Caps come in all different shapes and sizes. Use whatever you have that fits as long as the electrical specs are met.

If you are worried over 630v versus 600v, don;t.

[hourglass]

I wasn't worried about 600V vs. 630V. I figured that would be OK. I was mostly wondering about the 1/2-Watt resistor being OK and whether the composition of the capacitors mattered.

For my money, however, most of the differences between different types of capacitors can only be heard by those people who spend $300 on an audiophile-grade IEC power cable.

FWIW, I now have the 5150-II. I used to have a 5150. I've been listening to a bunch of stuff I recorded with the original 5150 and I've never been able to get that tone out of the 5150-II. At the time, it suited the band I was in. Now I want the sound of my old amp back. Typical...

ryan

[hourglass]

Here are some clips of before and after the mod.

Before:
http://www.ryanadam.com/5150/5150-cap-test-A.MP3

After (knobs at same settings as the one above):
http://www.ryanadam.com/5150/5150-cap-test-B.MP3

After tweaking the knobs to clean up the mud:
http://www.ryanadam.com/5150/5150-cap-test-C.MP3

A & C together (A is left, C is right - you can pan back and forth to hear the differences):
http://www.ryanadam.com/5150/5150-cap-test-Both.MP3


With the knobs set the same you can clearly hear how much low end is added by changing back to the original 5150 specs. For both of those the LOW and RESONANCE knobs are maxed and I still wasn't getting enough low end from the stock 5150-II. Since there's more than enough with the mod they've both been back off to around 6 or 7 on sample C and I raised the mids quite a bit.

ryan