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My $50 Mike Matthews/ETI amp

What can you buy for $50 these days? Not much, eh? Well if you’re a guitarnerd like me, you can buy one of these beauties.

Last year, I did a story on a tiny amp with a big punch… the Electro Harmonix Freedom amp. (check it here.) This tiny amp sounded HUGE and has a bit of a cult following in the Electro Harmonix community. Tim was kind enough to make me a clone using the chassis of my Goldentone 2×12 combo.

Anyway… this week I was looking through eBay and amps that were for sale nearby to me when I saw a blurry photo of a familiar looking amp with the description “Great amp. No Distortion.”… with an opening bid of 50 bucks.

My guitarnerd senses were tingling. Straight away I suspected this was an Electro Harmonix amp. I had a look at the other photos and noted the similarities between this amp and a Mike Matthews Dirt Road Special.

The first similarity was the three screws on the top of the amp. Here’s the Ebay amp…

And here’s a Dirt Road Special…

Perfect match. That’s one tick in the box. The next was the back of the amp. Dirt Road Specials have a small square cut out to help shift air inside the small cab. Here’s the eBay amp…

And here’s a Dirt Road Special…

Apart from being in a different spot… they matched.Actually, on further review, it looks like the back panel has been reversed, so maybe the assembler at the Electro Harmonix factory grabbed the back board the wrong way round, covered it in vinyl and attached the small square of shadecloth/fabric before fitting it to the amp. This may also explain why the speaker is sitting to the right side of the amp instead of the left of the DRS. The assembler probably fitted the baffle board the wrong way around.

The last similarity was the power cord. On these amps, they are on the right hand side, near the bottom. So, again… eBay amp.

And the Dirt Road Special…

So yep… this seemed to be a modified Mike Matthews Dirt Road Special… for 50 bucks… 20 minutes drive from my house. I prayed that no-one else twigged to what this amp really was, and 2 days later, I was the only bidder. Yesterday I drove round and picked up my prize, drove straight home and plugged in my G&L SC3. The howl that burst out this little box confirmed one thing at least… this little box KICKED ASS.

As mentioned… this amp has been modified. A lot. The controls look nothing like a Dirt Road Special. Instead of the simple Volume/Tone/Bite controls plus the Small Stone phaser ‘Rate’ control, there were 2 volumes, a gain, bass & treble, a frequency dial and a lot of things saying ‘sweep’.

After a bit of mucking around, I found that the sweep circuit acted like cracking on a wah pedal at a certain point… a’la Michael Schenker. You pick what frequency you want and it certainly adds a big dimension to the sound. Dialled back, this amp sounds really meaty… a lot meatier than a standard Freedom Amp or Dirt Road Special.And if you dial through the freq range, you get a real phaser/wah sound. It’s quite cool.

Flick to the EQ circuit, and it’s pure Mike Matthews. That ‘Hot Snakes’ treble is there… a lot of it. It also has what looks to be a knob from six different toasters, radios and television sets… no two are the same and NONE are Electro Harmonix knobs.

I took the amp into Tym Guitars today for Tim to have a look over, as we’re both big fans of these amps. I plugged it in and Tim was blown away with how meaty it sounded. He noted that it didn’t sound like his Freedom amp… it was a lot bigger. I flicked off the Sweep circuit and Tim agreed that it sounded a lot like the Freedom amp now. As the controls were very un-EH, we took the back off to have a look. What we found was pretty surprising…

This had no Electro Harmonix circuit boards in there… in fact… it looked nothing like the guts of a Dirt Road Special…

The circuits were a lot better made than typical EH circuit boards (which looked almost hand drawn) … and these were stamped with ‘ETI’, which we researched and found were made by a US OEM company called Electro Technik. So either this is a weird Mike Matthews amp made with OEM parts (which isn’t unusual for Mike Matthews)… or someone got a Dirt Road Special, gutted it and fitted another amp inside. Tim says judging from some of the parts used, this amp might even be 100 watts. It’s certainly loud enough for me, what ever it is.

Either way, this thing sounds spectacular. I can get this thing to feedback… Mesa Boogie Mark 1 style. Not bad for a solid state amp. I’ve read in forums that a lot of people think that a lot of the unique sound of these amps come from the actual size and shape of the box. I’m inclined to agree now. This amp is miles away from Tim’s original Freedom amp, but sounds really similar. Not bad for 50 bucks.

Ten minutes after playing it at Tym’s she stopped working. Tim said it was probably a dry solder joint, and he said that the wiring needed redoing anyway as it looked a little ‘home made’… so she’s getting a going over, which includes me designing a new EH style aluminium faceplate for her. I am thoroughly stoked with my purchase and look forward to using her for many years to come.

••update.  I did some more research and it seems this amp may be a lot more home grown. ETI may actually stand for Electronics Today International, which was an Australian magazine that had kit guitar and hifi mosfet amps that the readers could build themselves.

This article here shows an amp called the ETI-466, which looks very similar to mine.  My amp has ETI-1424 written on it, so it may be a later model. So it’s looking like my cabinet may be EH, everything else is ETI. I’m loving this… (holy crap… just found out that the ETI-466 circuit is for a “300w amplifier”…wow.)

Oh, and here’s an archive website of ETI circuits. (click here)

•••update: I found some more information about ETI on the fabulous ozvalveamps website. A complete listing of all their projects. (click here) It even has my amp listed “ETI 1424 – Versatile guitar preamplifier: Nov 87”

••••update: I found an electronics website run by Marty, who has copies of every issue of ETI magazine ever printed. I asked if he could track down the Nov 87 issue featuring my amp, which he is in the process of doing. He also added the following info:
“Looking inside your ‘Ebay Amp’ i can tell you the amplifier module is the card in the bottom-right of the cabinet. It’s an old “ETI-480” Amplifier, (obviously i have those details in my mags too). The 4 transistors fitted means it’s the 100Watt amp, but there is also the same kit (identical PCB with shorter heatsink plate) with only 2 transistors mounted, which is the 50Watt version.”

“Also to note, Silicon Chip magazine revised the design of the old ETI-480, and released a kit called the SC-480, which has far better specs and stability than the old ETI-480 Amp……i thought you should also know that too, incase you wanted to improve it later in life…..but maybe the old 480 has a dirtier (better) tone to it, so who knows .”

“From what i remember, the ETI-1424 kit was a guitar preamp/processor, i think it was capable of 4 inputs, mic/guitar and/or line inputs, i had a feeling it *might* also have a built-in basic chorus/flanging effects too….although i might be thinking of a later guitar-FX ETI kit??? (probably ETI-1424b or something).”