Modding 5150 II lead channel to 5150 spec

[::XeS::]

Does it worth the effort? It's a pretty simple mod (change 2 caps with other caps and some resistors).
I found some comparison clips before/after the mod

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

After
http://www.ryanadam.com/5150/5150-cap-test-B.MP3

The sound is pretty different. The II is more open and tight, with less bottom ends while the Modded is darker, spongier and with great bottoms.
What do you think?

 

[nwright]

Link to the mod? I've been contemplating doing this for a while, but can't seem to find the right schematic or tutorial.

 

[::XeS::]

From the Peavey forum:

Hello, if anyone is interested in this topic, I jut got a reply from James Brown @ Kustom (previously of Peavey) with the following explanation:

"I can only assume that the 6505+ is identical to the 5150 II since I was gone before Ed left Peavey and they changed the name.....if it is, you can take your amp to a qualified service center, and they can remove C17(470pF) and replace it with a 470K and 0.0022uF capacitor in parallel (or they can just tie a 470K and an additional 0.0015 uF cap across C17, without removing C17). Then they would change C2 from a 0.001uF capacitor to a 0.022uF capacitor. The result is that the attack is a bit floppier and thicker sounding, and the gain is much heavier sounding and not as tight/chunky."

 

[Sloan]

fucking hell, i definitely preferred the second clip.
mod seems easy as fuck. If i had a 5150II here, i would totally post a HOW-TO with images.

 

[nwright]

From the Peavey forum:

Hello, if anyone is interested in this topic, I jut got a reply from James Brown @ Kustom (previously of Peavey) with the following explanation:

"I can only assume that the 6505+ is identical to the 5150 II since I was gone before Ed left Peavey and they changed the name.....if it is, you can take your amp to a qualified service center, and they can remove C17(470pF) and replace it with a 470K and 0.0022uF capacitor in parallel (or they can just tie a 470K and an additional 0.0015 uF cap across C17, without removing C17). Then they would change C2 from a 0.001uF capacitor to a 0.022uF capacitor. The result is that the attack is a bit floppier and thicker sounding, and the gain is much heavier sounding and not as tight/chunky."

I'm pretty adept at using a soldering iron, and I've done a few mods to pedals, and wiring my own guitars. I wanna try this, but I have a few noobish questions...

When he says "tie a 470K and .0015uF cap across C17", would I just solder the resistor and cap to the existing cap's legs? So it would in essence be 3 legs on each side soldered together?

 

[::XeS::]

I think he means like the bias mod, where you solder a resistor and a pot where there was a resistor before

 

[nwright]

I think he means like the bias mod, where you solder a resistor and a pot where there was a resistor before

right, but in pics I see, it's usually the additional component is soldered to the legs of the original component, NOT both components legs crammed into the holes on the PCB and soldered.

That's what I was getting at. I would probably solder the 470K resistor and the .0015uF cap to the original C17 component, but in my mind I'm seeing 3 pieces all crowded together and it getting messy.

I think I am going to try this. Worst case scenario is I buy a new board from Peavey, right?!?!?

I'll take the chance if I can get my 6505+ sounding more like a regular 6505.

 

[onqel]

Here is the frequency-response of the original (green) and the modded (blue) version.. This is a plot of the frequencies going into tube number two, just after grid resistor..

As you can see, the mod/conversion adds pretty much lows.. and this is the biggest difference between the 5150/5150II .. but there are several differences so this isn't a complete conversion..
(I already had the schematic drawn for my new project..)

 

[::XeS::]

If there is some space, you can also solder to the cap 2 very little wires with the resistor at the end... it depends.
Anyway, judging from those clips, I don't know....after the mod it has more body and more bass, but I think the 5150 II has a great balance, it's more open and more tight...a little too much fizzy but you can tame it with some eq..

 

[barricade]

Are there any mods for Peavey 5150 mk1 ? tnx!

 

[nwright]

If there is some space, you can also solder to the cap 2 very little wires with the resistor at the end... it depends.
Anyway, judging from those clips, I don't know....after the mod it has more body and more bass, but I think the 5150 II has a great balance, it's more open and more tight...a little too much fizzy but you can tame it with some eq..

One thing to remember on those clips...I found a thread where this user posted these exact same clips on another forum...He explained that in these clips you posted, BOTH amps had the bass and resonance maxed and the EQ was identical for both clips (pre and post mod)...In this thread he also posted a clip where he re-EQ'd the modded amp to reduce the mud.

 

[::XeS::]

Yes it's true.
This one: http://www.ryanadam.com/5150/5150-cap-test-C.MP3

 

[HeadCrusher]

Are there any mods for Peavey 5150 mk1 ? tnx!

Apparently there is something called the Bias mod. But I don't really know what it does. Some guys here do though.

 

[nwright]

the bias mod allows for the bias to be adjusted rather than fixed. The 5150 was designed with a low bias in mind, as EVH preferred the tone when the amp's bias was in a low range which allowed for the crossover distortion to become part of the amps voicing. Biasing the amp hotter (for some) is preferred, as it can help get rid of the fizzy/fuzzy nature of the amp and get the power tubes working a bit more. the amp is cold biased from the factory stock, I've read as low as 12mA's...I'd say 16mA's is more the "normal" range...the bias mod usually takes the amps mA's to around 32.

There are other mods that are common with these amps, most notably adding new transformers, adding a choke, clarity mods, and more.

Also, the 5150II to 5150 mod talked about in this thread is offered by a number of mod guys (notably FJA mods). the choke, tranny and clarity mods are also offered for the 5150 II, IIRC. Voodoo Amps and FJA are the ones I read about the most online.

How much of the amps inherent tone is left after all these mods is up to debate, though!

 

[JeffTD]

I'd advise anyone who actually likes the tone of a 5150 to stay far the hell away from any mod FJA would do to the preamp section (clarity mod and other junk) - it really just pussifies the head for what we're doing.

This isn't a complete mod, though - good start. I'd like to see a full mod, getting them identical... then I could consider getting a 5150II and just do the mod myself.

 

[Sloan]

I'm pretty adept at using a soldering iron, and I've done a few mods to pedals, and wiring my own guitars. I wanna try this, but I have a few noobish questions...

When he says "tie a 470K and .0015uF cap across C17", would I just solder the resistor and cap to the existing cap's legs? So it would in essence be 3 legs on each side soldered together?

Yeah, that's right, you could also just replace c17 with a capacitor equal to both of the caps vaules, but then you would have to access the trace side of the board.

You can't really hurt anything messing with the preamp stuff here, but you can get zapped, most likely some of the 12v running to the tubes. It kinda sucks but usually won't kill you.

 

[Sloan]

I'd advise anyone who actually likes the tone of a 5150 to stay far the hell away from any mod FJA would do to the preamp section (clarity mod and other junk) - it really just pussifies the head for what we're doing.

I've never been a fan of the FJA guy, and other amp mod people, simply because they seem very uptight about sharing any information, opting to reply with a "yeah i can do that, check out my website" etc... I understand the fear of losing business, but hell, I do amp work and try to get the info out as much as I can. Most people don't want to risk messing up their amp or getting fatally zapped by high voltage so they're not going to do it anyway.

Whenever I get the chance I try to share what I have learned working on amps so that people understand that it's not magic and gain a little insight into how they can utilize their equipment to get the best sound possible.

 

[kaomao]

I did the bias mod years ago and to me it didn't sound so totally different.
I posted clips and they sounded different, people liked more the premodded amp. As I said in that old thread, I think I fucked up with mic positioning, since the amp sounded about the same before and after mod.

 

[hourglass]

Hey guys,

Those are my sound clips.

NWright brought the fact that this was being discussed here to my attention.

When I get home tonight I'll take some pictures of the mods. It's absolutely super simple and makes a huge difference. I regretted selling my original head and was about to buy another one before I gave this a try.

And I couldn't agree more about other mods to these heads -- if you like the sound of your 5150 you should stay away from bias mods and all that shit. The amp is biased cold because that's how it's designed. If you don't like it then you bought the wrong amp. My best guess is that this is simulating what the bias would be like if you took the voltage down with a variac. Since the 5150-II has a bias adjustment you can hear for yourself just what changing the bias does. I played with it a few different times and adjusted it by ear before checking with a meter. Every time I came back to within a few mv of the recommended setting.

As for putting the cap & resistor in parallel, someone already described the correct way. Either leave the stock cap in there and add the two components to it's legs or cut out the stock one (leave the legs long) and then solder the new cap & resistor to the leads. You can't get to the solder pads on the main board unless you take it out of the chassis, and that seemed unnecessary in this case.

ryan

 

[nwright]

Man, Ryan, thank you thank you thank you.

I was THIS close to trading out my 6505+ for a regular 6505 and potentially willing to lose money to do it. Now I don't have to.

I've been really leaning towards my XXX lately, but maybe doing this mod will swing my opinion back into the 6505's corner (not that I disliked my 6505+ at all).