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the_bleeding 2007-03-22 01:06

AMP MODS!!!!1111.... (and contruction)
This thread i make so people can share their building/modding knowledge for heads and cabs.

So i'm thinking of building and amp / buying a cheapo (used jcm 800 or an ampeg or something) and modding the shit out of it.
I'm interested in cutting out shitty fuzz, adding a fuckload of tight distortion, and pretty much learning what i have to do to shape the tone of an amp and turn it into a monster. Anybody know how do to this?

So far, all i know is how to change plate resistor values, and that the higher the resistor = the higher the gain... but thats it... Is there anything else i can do? Jopop, i'm lookin at you.

Soulinsane 2007-03-22 02:09

You need to take a analog electronics class if you want to mod a tube amp. They are ancient technology by modern standards but mods still require in depth knowledge to get the most out of the work. There are a lots of things to know about amp function and I'm not just talking about music amps but the basics are the same. Placing a higher value resistor in a circuit will not do shit unless you know where to put it. Put it in the wrong spot and you will release the magic smoke from your amp and it will work no more.

I'm not about to start teaching complex electronic fundamentals on a forum. I don't have the time and it is wasteful. You would learn faster by working for free at your local TV/stereo electronics repair store and taking a class or two.

I will post simple mods for amp and cabs but go to school to learn to most.

Just remember to be damn careful.

Jopop 2007-03-23 19:16

Like Soulinsane said, tube amps are very simple devices, solder points are very large, components are few, the design is simple, and so on :)

The JCM 800 is a great amp to start modding.

Here's some pointers:
More gain & bass: Add a cathode bypass capacitor (or increase the one already present).
More gain (clipping really) & compression: Increase the plate load resistor.
Just more gain and less buzzy tone: Modify & fine-tune the voltage dividers between gain stages (will explain more throughly tomorrow, it's late here).

Tone shifting: Modify coupling capacitors (google it) to a larger value for a darker sound, smaller for brighter. Change the values in the tone stack for a drastic change in tone, higher value means lower frequency (for example, change the bass cap. from 22n to 220n for a massive increase in bass and low mids, used by ENGL for instance). is a great tool for tone stacks.
Google "marshall tone stack" to find out more.

More clarity: Muddiness is often caused by "too many" components, i.e. the designers have added tons of capacitance to "safe" the design so it won't crap out no matter how crappy it gets built and how much off standards it is (too much high freq. cut between stages to tame over-excessive buzziness is an example, it muds things up, they should rather have less gain and then less cut), they add huge amounts of gain in each stage but then cut tons off before next stage to keep it from overloading (adding small amounts of gain in each stage and fine-tuning is FAR superior to going all-out in each stage and then just chopping off a lot to not get "bad" distortion in the next tube (blocking distortion)), etc.

A nice and solid power supply gets you a long way - check that you have a diode rectifier and plenty of filtering, adding some more caps in parallel over the existing filter caps can help. There's more on this but i will get back to it.

Google all the things you don't understand, like "voltage divider", "plate load resistor", "cathode bypass resistor" etc. Check out the preamp section of amps you like, and observe the small differences (they are mostly VERY similar).

Here's a VERY nice article for the JCM 800:

Also, read the info material on and check out , esp. - nice theory on tube amps.

Also maybe some general theory, like Ohm's law, Kirchoff's laws etc may be helpful..

Bedtime, sorry.

the_bleeding 2007-03-23 19:25

ahhh beauty :)

I will research all of that, and i know the basic physics laws, they were the only thing i was mildly interested in in physics class. I will do my reading.

Oh and Soul, i'll be lookin for a class to take so i can get familiar enough with this stuff to build my own.

Soulinsane 2007-03-23 19:31

Nice links :beer: You are a very brave man to want to explain all this on a forum. I figured it was going to take me hours. I think the hardest part for me was going to be explaining how to analyze and calculate circuits in order to derive the target component values. There is just so much to know.

Good luck!

Soulinsane 2007-03-24 03:07

Fast and easy Cab wiring mod.
This mod is for any speaker cabinet. This mod will help add clarity and frequency response to your tone; mostly in the low mid to bass range. For simplicity, I will explain these instructions as if I were performing this mod on a closed-back 4x12 speaker cab, but is only the example. This mod can be performed universally on absolutely any type of speaker cab.

Important note: These instructions will only cover what the cab is wired with and not change its wiring schematic (or change how it is wired). Basically, when finished, you cab should be wired the same but with better wire material.

First step is to assess if your speaker cab needs this upgrade. The focus here is to determine what wire gauge diameter ( AWG ) is currently being used in the cab. Most cabs use a small diameter wire because it is very economic when manufacturing a large number of cabs. Better wire adds a huge cost when you have to wire hundreds if not thousands of cabs. The AWG of a wire can be found written somewhere on the length of the wire or you could just measure the diameter of the conductor to get a close guess. Small wire diameter will result in poor signal transfer from the amp to the speakers for many reasons to detailed to post about here. Anything 15 AWG or higher AWG will need to be replaced.

FYI: The bigger the AWG # the smaller the wire diameter. The smaller the AWG # the bigger the wire diameter. Keep in mind stranded core wire will seem to measure larger in diameter than solid core wire due to cross reference parallax error. Higher frequency signals travel better near the surface of a conductor and stranded core wire was invented to accommodate those frequencies. It was designed as one wire with a lot of surface area carry high frequency traffic far better than solid core wire.

Materials needed:
Soldering iron
Electronics solder ( not plumbing solder )
Female spade push-on connectors ( that will accept you new wire AWG )
Pliers to crimp the spade connectors
Wire strippers ( a knife will work if your careful ) wire.

The new wire will need to be STRANDED COPPER WIRE with an insulated wrapping to help keep it oxygen free. Stranded copper wire is ideal to carry high frequency signals without problems. Do not buy solid copper wire or any type of aluminum wire. Stranded copper wire is the best you can buy. Ignore "speaker wire" as it really isn't designed for use inside a speaker cab and will have a measured capacitance even in short lengths. It is better to keep single insulated wires ( stranded core ) in a cab separated about an inch apart to prevent capacitance from building up and ruining the signal. There room inside a cab so use it.

The new wire also needs to be at least 14 AWG. I would not use anything large than 12 AWG unless you really are good with soldering. I used 10 AWG in my cab as overkill but it also very hard to work with. I purchased 10 feet of 10 AWG stranded copper wire at a Home Depot hardware store for $0.40/foot.

12-14 AWG stranded core copper wire is perfect the prefect mod.

The Work:
Draw out how your cab is wired on paper before you disconnect any of the old wire just in case you get confused later. Be very detailed. I will not cover wire schematics in this mod. The new wires should be connected to the same points as you old wires.

Measure out each length of wire you will need. The shorter the better but leave enough length to be able to move it away from other wires or things the wire might vibrate on.

Strip the insulation off the wire ends and twist the strands hand tight. With the solder iron tin all the twisted wire ends.

Next, depending on the cab, wire ends will now need to be soldered to the cabs input jack(s) terminals, but first you will need to desolder ( remove ) the old wires from the jack(s). This can be done by simply holding the solder iron to the where the old wires are soldered to the jack and lightly pulling on the wire at the same time. The solder will melt and the wire will pull free. Here's a nice soldering guide, but there are hundreds online to read.

Once the needed wires are soldered to the jack, put the female push-on spade connectors on the other tinned wire ends and crimp them on using the pliers.

Remove one of the old wires from the cab by pulling and wiggling the connector off. Replace it with the new wire by pushing and wiggling the spade connector onto the correct male speaker terminal. It should fit tight. Repeat this process one wire at a time until all the old wires are replaced by the new wires.

Advance Tip: If you are really good at soldering then add tinning on the female spade connectors and once pushed on the male speaker terminals, using the solder iron, apply just enough heat to remelt the tinning on the female shade connector so that both the male and female terminals fuses together with solder. This will provide a rock solid connection but requires a lot of skill to know how and when to remove the solder iron. What makes this hard is the speaker magnet. The magnet will pull very hard at the solder iron and could take it out of your hand and put the hot end through the speaker cone. I seen it happen once so be very careful.

Once everything is connected, make sure none of the wires length contacts anything or comes within a inch of the other wires. This will prevent the wires from rattling or building a capacitance.

The wires should look like this when finished.

And this, but ignore trying the foam mod until I post it.

Once everything is back together you should notice an improvement in tone. Mostly in the low range frequencies. The improvement comes from the lowered resistance of the bigger gauged wire, better frequency attenuation of the stranded copper core, and removed capacitance due to careful wire placement. However little difference this new wire compared to the old wire makes on short lengths measured by a multimeter, this mod does make a real difference when measured on a O-scope. Musical tone is noticeable to the point that even a untrained ear will hear it.

This is an easy and cheap mod. The key phase is, "Bigger gauge, stranded copper wire is better". No body should have much problem with this mod but post questions if you have them.

Good luck.

Jopop 2007-03-24 07:24

Also, after doing Soulinsane's mod, remember that your cable from your amp to your cab is now by far your weakest link - buy a pair of jack plugs and use the biggest wire you can shove into the plugs and solder yourself. I use 10AWG inside my cab and i think i have 12 or 13 AWG speaker wire inside a modified jack plug (cut it open and bent it out).

Soulinsane 2007-03-24 07:40

Originally Posted by Jopop
Also, after doing Soulinsane's mod, remember that your cable from your amp to your cab is now by far your weakest link - buy a pair of jack plugs and use the biggest wire you can shove into the plugs and solder yourself. I use 10AWG inside my cab and i think i have 12 or 13 AWG speaker wire inside a modified jack plug (cut it open and bent it out).

Absoluely correct, but you spoiled my surprise. The speaker cable is the weakest link after my mod, but it can be nulled with high quality cable and good connectors. I make my own speaker cable with MOGAMI 3103 speaker wire ( 12 AWG dual speaker wire design for outside a speaker cab ) and G&H Megafoot .500 phone connectors to mate my amp and cab.

Edit:I guess I now have to explain how to build your own badass cables next.

the_bleeding 2007-03-24 11:53

Originally Posted by Soulinsane

Edit:I guess I now have to explain how to build your own badass cables next.

cant you just buy a kit? The guitar store local to me honestly has a HUGE rack of different gauge wires with a giant sorted box full of different plug types... or is there some speshul secret you know ;)

Jopop 2007-03-24 13:11

Originally Posted by Soulinsane
Absoluely correct, but you spoiled my surprise. The speaker cable is the weakest link after my mod, but it can be nulled with high quality cable and good connectors. I make my own speaker cable with MOGAMI 3103 speaker wire ( 12 AWG dual speaker wire design for outside a speaker cab ) and G&H Megafoot .500 phone connectors to mate my amp and cab.

Edit:I guess I now have to explain how to build your own badass cables next.

Where do you get that cable + the plugs? I am about to order some Mogami signal cable, so maybe I'll get a roll of speaker cable too (my current one is a little lacking, AND I'll be upgrading my car stereo soon)..

sqol 2007-03-24 14:47

Now that means we all need to upgrade the wire from the output transformer to the speaker outputs ;)

Soulinsane 2007-03-25 05:14

Custom quality instrument cable construction.
Originally Posted by sqol
Now that means we all need to upgrade the wire from the output transformer to the speaker outputs ;)

You're getting the right ideal :) You could have the best gear in the world but you need high quality materials connecting it all to get the most out of that gear. I can not emphasize the importance of good cable, wiring, and solder joints enough. Any musician worth a damn will tell you the same thing. All it takes is one solder joint, wire, or cable of poor quality to ruin you tone. Why make your own cable? Because its cost efficient, construction quality is better, and you get the lengths you need.

Continuing with this theme, I will explain my top secret cable making skills. I've spent hundreds hours of researching cable stats and materials, comparing everything. This post will reflect my final research results, choices in materials, and supply links.

Instrument cable:
Mogami w2524 guitar cable has the best stats I've ever seen compared to other cable manufactures that publish their cable stats. Basically, if you can't find stats on a cable you don't want it. The difference you hear between this cable and most other cables is like night and day. I consider this to be the best cable in the world, even compared to instrument cable that cost hundreds of dollars/ft. It is about as neutral, transparent, and quiet as a cable can get.

This is the cheapest place I have found it at $0.52/ft. Average price is $0.75/ft, but I have seen it as low as $0.37/ft in the past. If you can find it any cheaper than let me know.

Neutrik phone plugs are my favorite plugs to use, especially the series-C plugs. They are absolutely solid badass plugs for both instrument and patch connections. They do cost a bit, but are top of the range quality plugs and I've never had one fail. They range from about $2.00 up to $5.00 depending on the plug type and can be purchased just about anywhere. Here is an awesome buy! I use the Neutrik NP2C-BAG, Neutrik NP2RC-BAG, and Neutrik NP2RCS plugs. It's almost like the Neutrik series-C plugs were designed for use with Mogami w2524 cable. They are a perfect fit for each other. I don't use the gold plated plugs because there is no point unless the jacks they are plugged into are gold plated to and, most of all, I've never found any evidence that plating makes a real difference, so why pay more?

FYI: Use only the mono type 1/4" phone plugs with instrument cable or you will have big problems.

Now that you have everything, all you have to do is solder the plugs onto the desired cable length. Seems easy right? There are some important things you need to know first about stripping the Mogami cable. There is a layer of black PVC that needs to be stripped from the end of the clear insulation. Don't question it it. Just do it or the cable will not perform as it should. A fully prepped cable will have two hand twisted strands and will be tinned with a solder iron. It should look kinda like this once stripped, twisted, and tinned. Ready to have the plug soldered on . The strands in the middle of the cable should be soldered to the plugs tip terminal and the shielding strands should be soldered to the plug sleeve terminal. It should look kinda like this but not broken. Put the casing on the plug. Now test the constructed cables resistance with a multimeter to make sure there are no shorts or opens where there shouldn't be. Done.

Make sure you slide the plug casing on to the cable first before you solder the plug and cable together or else you will have to desolder everything to get the casing on the plug.

Don't make cables any longer than 30' or the signal it will carry will start to diminish.

Practice soldering for about an hour or until you know you are ready to tackle this project. To much heat applied to the cable when soldering will melt the insulation and ruin the properties in that part of the cable if not ruin the plug in the worst case. To much or over heated solder joints will also ruin tone by acting like a resistor. Bigger the blob isn't better the job. Soldering is easy but it takes some pratice.

Always remember to tin the twisted strands of the cable and the plug terminals before you solder. It will help make the prefect solder joint. Use just enough heat and solder and the joint will be prefect every time.

Summary: I hope this saves someone from paying $50 on a pre-made 20' Mogami guitar cable with Neutrik plugs, because now you know how to make that same cable for $15. Making the prefect cable only requires decent soldering skills, good cable and good plugs. That's it. If you got any questions then ask.

Good luck :beer:

Edit: I'll post my links for speaker cable materials later, but their construction is basically the same. The only difference is that speaker cable is balanced while instrument cable is unbalanced.

Soulinsane 2007-03-25 20:43

Custom quality speaker cable construction
Now for the speaker cable. It is basically the same process as instrument cable construction but with balanced cable.

Mogami w3103 2/12 AWG conductor speaker cable is what I use. Avoid 4 conductor in quad configuration cable; its good for triamping only and not ideal for short runs between amp heads and cabs. Do I use w3103 because I have a hard-on for Mogami cables? Not at all. Again, I put hundreds of hours comparing stats and performance test results into dozens of different speaker cables before coming to my final choice. It surprised me that Mogami was again the superior choice. This stuff cost a lot but the good news is you shouldn't need but a few feet of the stuff. Best price I've ever seen for this cable. This is were I got mine. The bad news is the shit is thick ( just under 1/2" in diameter ) and there are not many phone plugs that can accept the stuff.

G&H MEGAFOOT plugs are the only things I know of that will accept this cable snug. They all cost about the same everywhere. They are actually very nice high quality plugs.

And thats it. Solder it all together and remember to tin the cable stands and plug terminals first. I like to add some shrink wrap around the plug and cable for add protection and stability.

Summary: This cable makes a huge difference in tone and will not cost you much to make compared to buying it pre-made. Any question?

Good luck :beer:

Soulinsane 2007-03-26 04:27

Ok, I can see people are viewing the thread but what disturbs me is that no one is asking questions all of a sudden. I need to know if anyone is getting shit out of this thread or I will stop wasting my time. I have a lot of knowledge to share but damn wasting my time typing it out.

I've opened myself up here so ask away. This thread is about easy mods. Predators are waiting to charge you at least 3x more than what I'm given for free. I've hidden secrets for years, thinking it would give me a musical edge, but the only real edge is hard work. Now is the chance for me to share more. No one will be able to take your cash on over priced shit if you read my post, but give me some input or I will share no more.

If you read me then post or I'm going to stop posting my brain dead upgrades :beer2: I can spend my time in better ways.

Soeru 2007-03-26 04:50

Oh I'll have questions for you soon enough, I'm still just trying to digest all that info. :p

Soulinsane 2007-03-26 07:12

What is this :p about? I'm sure I know tricks you don't so don't get ahead of yourself young grasshopper.

I believe you have questions now. Ask away...

Take the pebble from my hand ;)

Soeru 2007-03-26 07:19

Haha never mind I read the speaker cable mod thing again twice and now I got the grasp on it. Really informative, thanks, I may attempt this sometime after I learn to solder. :beer: I do feel like my Framus 2x12 cab could use a little more low end... I'll also be doing the foam mod to it at some point too.

I use Mogami instrument cables and you are right, miiiiles ahead of any other cable brand I've tried. I have some monster cable and a cordial(not bad, has neutriks), but the mogami blows it the fuck away. Unfortunately I have Planet Waves speaker cable(oxygen free), but I wanna upgrade everything including patch cables to some mogami when I get the chance.

Hey man, check out my other thread about what soldering kit I should pick up please. ;)

Soulinsane 2007-03-26 07:57

Before you try that foam mod read my next mod post first. Please! It will not be much but there are a few things I need to explain before the foam mod. I will actually include the details in the foam mod lesson.

I seen your thread about solder irons too. Both of your choices will serve you well even though there are other crazy expensive irons on the market that do many other functions. Expensive solder irons do have a place in the world, but for most music project mods the irons you posted in your thread are beyond perfect. 15-30W pencil irons are the max anyone should use for basic electronic soldering. Practice is all that is needed, but reading a few guides will definitely help too. Tinning is about the most important thing you can ever do when soldering electronics. This isn't rocket science after all ;)

Edit: Btw, oxygen free cable is a sales hype in most cases. Mogami uses the words "oxygen free" to, but any wire that is insulated correctly shouldn't oxidize even in a hundred years.

Jopop 2007-03-26 16:40

I ordered lots of crap from redco.
Products Ordered: RED 12/2 Redco 12/2 Speaker Cable Quantity : 20 Price : US$0.45 W2792 Mogami W2792 Low Noise Mic Cable Quantity : 18 Price : US$0.50 RED INSTALL Redco Balanced Install Cable Base price US$0.12 Features/Options: Choose 1266A Color Yellow Quantity : 50 Price : US$0.12 RED INSTALL Redco Balanced Install Cable Base price US$0.12 Features/Options: Choose 1266A Color Blue Quantity : 50 Price : US$0.12

Had to keep it under 30 to skip customs. Redco 12AWG speaker cable from amp to cab (i can't really tell a difference between brands that are considered "decent"), 100 feet of Redco Install Cable (again, can't really hear much difference on high-voltage low-impedance signals, i.e. anything after the preamp) in fun colors, and two con + shield high-impedance ready cable (almost just the same as Soulinsane's, just balanced which means i can run semi-balanced and get NO NOISE, and no real thick plastic insulation). Not as sturdy as 2524, but in a studio, it doesn't matter. Better specs too (on paper). This has been one of the top workhorses in professional recording studios for guitars, high-Z mics and the like for many years, and it sounds pretty damn amazing. Low capacitance / foot and hardly any resistance makes this a very clear and bright (good bright, not "thin"-bright) cable. The shield is a fucking madman, with a served shield of about 95/0.12A there's just no HF noise getting into this bastard. I can't fathom why they sell this so cheap. It's not the cable to bring on the road, but it's unbeatable in the studio and at home if you can manage not to dance on top of it.

the_bleeding 2007-03-26 17:00

Originally Posted by Jopop
I can't fathom why they sell this so cheap.

shhh, dont say that, they'll find out and raise the prices :p

Man, all of this info is SOOOOO key, and Soul, its kinda hard to ask questions when you've already answered them all. All of this is VERY appreciated.

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