From: "Scott & Kathryn Colborn"
Subject: SF Champ mods and my "magic box"
Date: Wed, 30 Dec 1998 22:34:30 -0600
Hello Greg and Michael,
First off, I'm not a tech, so I'm going to describe in "layman's language" what I had done. Secondly, if you don't know your way around inside tube amps, have a pro do the work for you. There is voltage inside that can kill you. Since I don't know enough about the interior of amps to feel safe, I had the pros at Kendrick Amps do my work for me.
Here's what I had Kendrick Amplifiers in Pflugerville, Texas, do for me on the Silverface Champ (`70's vintage):
1) disconnect the tone circuit. We took the pots out of the amp and covered the holes in the faceplate with metal snap in buttons. My goal was to try and emulate the `60 Tweed Champ, with just a volume/on-off knob, and no tone circuit. I like the rawer sound, and I figure if your guitar sounds good (a Les Paul Classic with Seymour Duncan Jeff Beck Bridge pickup-a killer pickup, slightly overwound, and a S. Duncan classic `59 neck pickup), and you get the signal through the amp with as little tone-robbing circuitry as possible, you get great tone. The tone circuit robs you of gain as well, so we got more gain out of the amp for our work here.
2) disconnected the feedback circuit. As I understand, Fender ran the signal back through this circuit to try and keep the amp as clean as possible. This circuit robs the amp of gain and headroom. With this circuit disconnected, the amp really opened up; a lot more gain and louder, more headroom, and more raw tone! If you like edgey tone, and you could hear a SF champ stock and the same amp with the feedback circuit disconnected, you would grab the later in a minute.
3) a NOS preamp tube, a French 6V6 NOS power tube, and the tube rectifier. I have tried several other power tubes including a Ruby 6L6 which makes the amp louder yet, but the French 6V6 NOS tube sounds the best, the notes, while edgey and raw, are clearer and more distinct with the 6V6, and the bottom end is tighter and more solid. On the whole the French 6V6 sounds better.
4) had my bass player construct my "magic box" attenuator/headphone adapter using a schematic that Gerald Weber of Kendrick gave me for a starting point to build with. The "magic box" is an "L-pad", 15 watts, with a volume control, and the metal box with the "L-pad" inside accepts headphones or can be used as an attenuator to connect to another speaker or cab. The SF Champ wants to see about 4 ohms, and what works best is to connect a speaker load of 8 ohms to the magic box, which works to help the Champ accept the 8 ohm load. The "magic box" plugs into the speaker out of the SF Champ, and I either plug in headphones or an 8 ohm load, with a speaker cable of course. For my gig-rig I use a `72 Marshall 2 x 12 cab, 30 watt Celestions, 16 ohms each, cab wired for 8 ohms. Or, I have gone from the "magic box" attenuator to the 12" Celestion speaker, 8 ohms, in my Matchless Lightning 15 combo. THIS combination sounds killer, the open back Matchless cab with the box and SF Champ, but I hate to drag the Matchless around bars and clubs. So my second best cab is the Marshall 2 x 12 cab, it's a real close second, sounds really good. You won't believe how big this SF Champ sounds with a better speaker, or with a cab! It really opens this amp up. I play the SF Champ at a volume setting of between "7" and "8", and I'll put this tone up against most any amp/combo I've heard recently. It roars, growls, sings, has really edgey raw tone with sustain, I love it.
Just so you know what I'm comparing this rig to, I also have a `74 Marshall 100 Watt Super Lead half stack, the Matchless Lightning 15 watt combo, a Kendrick Black/Gold 35 watt combo, and my beloved `60 Tweed Champ. Comparing my Tweed to my SF Champ through their identical Kendrick 8" replacement speakers, the Tweed sounds better, so as I haven't tried hooking the Tweed up to the attenuator magic box and then to another speaker or speakers, I can only imagine that its going to sound superb! The attenuator "magic box" also allows me to connect to the Matchless speaker out, and from the attenuator box to the Celestion 12" in the Matchless. Crank out the Matchless, get those EL84's going without the preamp tube buzz/distortion, and then attenuate or lower the volume the speaker gets. So the attenuator "magic box" functions as a headphone adapter, allowing you to play at volume but not wake anybody, or as an attenuator. You can get different wattages of "L-pads", we used a 15 watt one because I didn't need a bigger one for the SF Champ or the Matchless.
Here's the cost of everything:
After playing this in real-world situations, I can't understand guys who want to use 50 watt or greater amps in real-life situations where they can't crank the amp up to the best level of tone for fear of getting kicked out or not asked back. The sound guy/gal is going to mic your amp through the house PA, so why not use a smaller amp, crank it out to get your superb tone, and just wail!
I played with this rig again last Monday night, and after our set the next band got up on stage, and their guitar player was really curious about my rig, so we talked and I explained what I had. He could of used the `60's Blackface Fender Deluxe on stage, but he asked if he could use my rig...and he said don't change anything, "I want to play this just as I heard it from the audience." Needless to say, playing a strat he sounded very good.
I have tried both a modded Tube Screamer and a Tone Pump with this rig and the LP Classic, and while the Screamer sounds very good, the Tone Pump pedal by Barber Electronics is fabulous. The notes are defined, sharp and distinct, while sounding big and huge. The Tone Pump doesn't color the tone of my rig as much as the Screamer, it boosts the tone, adds more sustain, but still has clarity way over the Screamer. My Screamer doesn't work well with the bridge and neck pickups together or just the neck pickup (sounds flabby, looses definition), but the Tone Pump is far, far better, I was ripping off notes ala Jimmy Page (at least in my own mind) and loving the articulation of the notes. The Tone Pump has two gain stages and sounds incredible, the best outboard pedal I've ever played (after just 30 minutes of using it). If you want to work with controlled feedback, you got it on the 2nd gain stage. This pedal doesn't sound artificial, buzzy, or metallic. Barber Electronics has a site, if you want, e-mail me and I'll send you a link for the Tone Pump.
Thanks to folks like Michael and others, I feel there is growing demand for small-wattage cranked amps of pure tone. If other players could just try a rig like mine, I sincerely feel that they would be converts in short order. Thanks for your interest in my rig and the "magic box." Good luck with your projects, and good vibes to each of you for the next year.
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