Hey there. This post may bore some of you to tears, but personally I find the history of all the stuff we use like amps, cabs, effects, and basses fascinating. If you’re like me, you might actually enjoy some of this. If any of what I’ve posted here is inaccurate, please let me know so I can make corrections. I’m not perfect, just close.
Most of this info was from research both here at the TB archives via the “search” function, and from older literature, articles, etc. I also e-mailed Dave Funk a couple of times and had him clear up a fact or two for me. Thanks to Dave for being so patient.
Back in the early 1990’s I became re-interested in bass amplification after coming across SWR products. Not long after I was turned onto Eden gear and was struck by the similarities. Around that same time I came across a couple of used AMP amplifiers and did the same double take. (I wish I had bought those AMPs). Turns out the story is more convoluted and interesting than your usual Behringer blatant knock-off of any given product.
Over 20 years ago, Russ Allee, who designed the 360 and 370 amps for Acoustic left that company and started a new company called Amplified Music Products with a guy named Roger Smith. Russ had Steve Rabe, another ex-Acoustic guy, help design the preamp for the AMP 420 amplifier heads. The preamp section had an “enhance” switch, fixed frequency bass and treble knobs and four semi-parametric midrange bands. The amplifier also had a variable limiter and a crossover for biamping if you had another power amp. AMP also made a lower wattage version called the 260.
Steve Rabe left AMP at some point and founded SWR. He was across the street from Groove Tubes and designed the bass preamp that Groove Tubes used to sell. The GT preamp was identical to the front end of an SWR studio 220, just no power section. SWR’s studio 220 and SM-400 were designed by Steve and were pretty similar to the old AMP design except they used a 12AX-7 tube in the input gain stage, and the enhance switch was replaced with a variable “aural enhancer” knob.
Deciding that he wanted to offer cabinets as well as amplifiers, Rabe commissioned David Nordschow of Eden Electronics to make speaker cabinets for SWR. Up to that point Eden had been making PA speakers. Depending upon who you listen to, the development of the original goliath 4x10 + tweeter cabinet has a couple of versions. Eden claims that SWR wanted a two way cabinet (presumably a 15+horn) and David sent SWR the 410T as an afterthought, wanting to know what they thought of it. The other story is that Steve Rabe and David Nordschow collaborated on the design. In any event, Eden made cabinets for SWR for a while until SWR opted to make its own, presumably due to quality control concerns. The split was not entirely peaceful, but wasn’t quite up to the soap opera status of the rift between Nick Epifani and Jim Bergantino. After many years, Steve Rabe left SWR to found Raven labs, and subsequently retired.
Eden improved its quality control, and continued to make cabinets under its own name. Wanting to offer a complete line David released a couple of heads with a preamp designed by James Demeter. The Preamp was very similar to the VTBP-201, with the addition of a DBX-style two knob compressor. Later, David revamped the Eden amp line with the introduction of the “world tour” series, with a preamp designed by none other than Russ Allee. The front of the world tour series amps was very similar to the AMP-420 and SWR studio 220. There were only 3 semi parametric bands, and the compressor was a simple on/off switch. There was a variable “enhance” knob, but a crossover was offered only on the WT-800. Like the SWR, the Eden incorporated a 12AX-7 preamp tube, another departure from the all solid state design of the AMP-420.
Why was Allee available to consult for Eden? Well, AMP folded in 1988 and was reportedly bought by Gibson. Either Russ Allee designed the GB-440 for Gibson or Gibson just continued making the AMP-420 under the new Gibson GB-440 moniker. Rumor has it that Gibson made some changes that destroyed the reliability of the amplifier. (Imagine Gibson doing that to any company they’ve bought out).
Production of the GB-440 was halted sometime around 1990 and the unbuilt amplifiers remained in a warehouse for some time.
Recently Dave Funk was involved with Gibson as a consultant/contractor, and was doing repairs for them. One of the managers approached him and asked if he wanted to purchase the contents of a warehouse they were cleaning out. When he bought it he found the remnants of the GB-440 line, including enough spare parts to build about 30 amps. Since then Dave has made several improvements to the design, including better components, a timbre control, and a switch to select two different preamp voicings. There is no crossover on the head. Thus we have the TF-420.
If you’ve tried them, you know that despite external appearances SWR and Eden amps do not sound alike. The same is true for the original AMP-420. I have yet to try a Thunderfunk, but if it’s as good as the original AMP (and most who have tried both say it is) then I’ll like it better than the SWR and Eden, which are still two of my favorite amplifiers.
If anyone knows where Russ Allee is, let me know. I want to buy that man a drink.
History lesson - Thunderfunk/SWR/Eden, etc. 
i could tell ya what i know in another thread, but that's a thread that i bet would get ugly and end up being closed awful fast. 
