Ask Amp Man

Jeff Bober rocks the stage at the Maryland Music Awards with Rob Fahey and the Pieces, wielding a Kevin Brubaker model called the Extreme. Jeff currently plays in three bands and plans to perform even more frequently.
Photo courtesy of Maryland Music Awards

Our beloved Amp Man signs off after 13 years of answering readers’ questions from under the hood.

A big hello to all you Ask Amp Man readers worldwide, and welcome to yet another installment of your favorite column. But this is not just another of my monthly columns. No, this will actually be my last column. I know, hard to believe, right? You open or download your magazine every month and there's the Ask Amp Man column. It's been there ever since you can remember!

Well, you are indeed correct about that. Premier Guitar was launched in February 2007, and the Ask Amp Man column has been there since the inaugural issue. What you may not know is that I've been writing this column even longer than Premier Guitar has existed. Prior to the launch of the magazine under the name Premier Guitar, it was known as Musicians Hotline and it, too, had a column where you could ask an amp expert questions.

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Except for the gain issue reader Rick Patterson describes, this month's amp is in remarkably good condition for

its half-century lifespan.

Transforming a vintage pedal platform into a powerful player.

Dear Amp Man,

I have a '60s amp sold by Fender. It's a Regal R-1160 dual 6V6 with tremolo. Seems to be the same as a Lectrolab R600B. This amp does not saturate before almost full volume, and it's very subtle at that. I read your column on modifying negative feedback loops and I'm wondering if you could look at the schematic and show me where I would make this modification and what value caps you would recommend? I'm new to this sort of modification and would like to improve the tone without destroying the amp. If you need any pics, I can provide whatever you like.


All components and controls on this Regal R-1160 seem original, except this replacement speaker:
a Ted Weber Legacy Series.

Hi Rick,

Thanks for reading Ask Amp Man and thank you for your question. But even more, thank you for bringing this amp to my attention. I don't believe I was aware of Fender selling any amp that didn't have their name on it, but it does say right on the control panel “Distributed exclusively by Fender Sales Inc., Santa Ana, Calif.," so it's a very cool little piece of history, for sure. And to top it off, sans replacement speaker, it's in great shape!

Regarding your desire to modify the feedback loop in this amp to enable it to break up sooner: That's a good idea and a good place to start with many amps, but unfortunately not here. The first thing I noticed on the schematic you sent along with your question was that this amp doesn't even have a negative feedback loop! Not really unusual, but most amps without this tend to break up a bit more, so I was surprised that you say this does not.

Since both channels on this amp are virtually identical, why don't we leave channel 2 stock and modify channel 1 to bring it closer
to your expectations.

I would first suggest making sure the preamp tubes are not a contributing factor, and then possibly have a qualified tech give the amp a quick check to see if all seems well. Pay attention to the bypass capacitor across the output stage cathode resistor (Photo 1). While this doesn't control the amount of front-end gain in the amp, a bad or weak one can sure make an amp sound anemic.

If the tubes and bypass capacitor seem good but the amp doesn't have a lot of inherent gain, this could actually be an asset to some musicians. There are a couple of scenarios where lower gain is preferred—one being in a harp amp, but the other, more near and dear to guitar players, is if the amp is to be used as a pedal platform. In this case, the lower gain and higher headroom of an amp can really let the pedals shine. Some refer to such an amp as “pedal friendly."


Photo 1

That said, your desire is to get more crunch from this '60s jewel, so I do have a suggestion. Since both channels on this amp are virtually identical, why don't we leave channel 2 stock and modify channel 1 to bring it closer to your expectations? Sound good? Okay, let's go.


Photo 2

Hot modding. First, locate R7 in the amplifier (Photo 2). This is a cathode resistor for the first gain stage of channel 1. It is un-bypassed, so let's add a bypass cap across it to get more signal gain from this stage. I would use anything between a 4.7 µF to 10 µF, 25V DC. Plenty of amps use a 25 µF on up to a 250 µF cap, but anything that big may yield too much gain in the lower frequencies and that's something that would just muddy up the sound in a low-power, open-back amp such as this. Be sure to connect the positive side to the tube end of the resistor. If access to the resistor is too prohibited, connect the + side to pin 8 on the tube socket and connect the – side to the ground lug of the terminal strip.


Photo 3

Next, locate R15 (Photo 3). This will be one of the mixing resistors supplying the signal from channel 1. According to the schematic/parts list for your amp, this should be a 220k resistor. In your amp, however, both mixing resistors are 470k. This could also be a contributing factor in the lack of gain you say the amp has, but, regardless, let's leave channel 2 alone. I would suggest attaching a 220k resistor in parallel across the 470k resistor from channel 1. This will give you a stronger signal from channel 1.

There are a few other tricks that can be done, but some require the actual removal of components from the amp. The complete unsoldering and removal of components from tube sockets and terminal strips is often best left to someone with a considerable amount of experience in such matters. Other mods can require a bit of trial and error before a final component value decision is reached. I believe the modifications done above should give you an amp that you can push into overdrive much more easily, while leaving one channel cleaner for other uses. You could even get creative and use an A/B box to switch between the two channels for a lead/rhythm setup.

There you have it. I hope your Regal can now generate some royal sounds!

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The exterior resemblance between the Carvin Series III X and classic Mesa/Boogie combos resonates, but there are major differences under the hood—or, in this case, the red oak cabinet.

Bolstering an amp that boogied its way alongside the ’80s competition from Petaluma.

I know this column is called Ask Amp Man, but after writing it for a crazy number of years, the questions tend to start repeating. That’s why I’ve been writing about some cool amp projects that cross my bench. Some interesting questions have come in lately, so I’ll probably get to them soon, but this month I have for you an amp that I don’t see too often. It was made in the early ’80s, when some manufacturers were trying to compete with the big “M” (the one in Petaluma, California—not in the U.K.) by coming up with their own versions of amps that looked similar but definitely had their own take on an overdriven gain channel. Here’s one that “boogied” along: the Carvin Series III X.

As you can see from the picture, this one borrowed its looks from its competitor’s custom-shop amps, utilizing a cane grille cloth and a red-oak hardwood cabinet. It even went so far as to use an OEM EV 12L speaker, as was typically found in that other company’s popular combo of the time. While the subsequent generation of Carvin X amps typically utilized EL34 output tubes, this series used 6L6s in yet another nod to the competitor. Two switchable channels, reverb, and, of course, a 5-band EQ round out the visual comparisons. And that’s pretty much where the similarity ends. Now let’s take a look at some of the differences.

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When this ’80s Sundown Artist came in for rehab, Jeff Bober got a chance to examine an amp that was the unique vision of player and builder Dennis Kager, who began his career at Ampeg in 1964.

An ’80s amp that displays the singular perspective of player/builder Dennis Kager, with multiple effects loops and unique tricks.

Hello, Ask Amp Man fans. Well, I’ve decided once again to forgo a reader question and instead bring you the story of another cool amp that’s recently crossed my bench. This amp may not be well known, but it’s yet another offering from the amplifier hotbed known as North Jersey. The area was first put on the musical map in the ’60s by a little company called Ampeg, which became one of the largest, most respected amplifier brands of the day—and still commands respect. As in the modern tech industry, Ampeg employees spun off to start their own companies. One such “spinner” was Jess Oliver, Ampeg vice president and inventor of the Ampeg Portaflex B-15 amp, who left and formed Oliver Sound Company. (Maybe one day I’ll do a column on an Oliver amp.) Another Ampeg departee of note, who is well known in our boutique amplifier world, is Ken Fischer. In the mid ’80s, Ken began building his own amplifiers under the name Trainwreck. They have garnered iconic boutique-world cult status.

Yet another, unfortunately lesser-known, amp guru who worked at Ampeg in the early ’60s and eventually decided to strike out on his own was Dennis Kager. Having already established himself as a great repair tech, Kager, along with a partner named Dennis Bock, opened Dennis Electronics in 1967. Being a guitarist as well as an electronic technician (a vital combination for a guitar amp designer, IMHO), he also decided to design and manufacture his own line of amplifiers. In 1984, Kager began producing Sundown amplifiers. Amps with channel switching and master volume were becoming de rigueur for guitarists, and that’s what Dennis was offering. They became the amps of choice for many players, including John Scofield, Allan Holdsworth, and even James Burton, so let’s take a look at this fine example I recently encountered.

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