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In this review, we're going to be taking a close look at a couple of Gary Gerhart designed tube guitar amp "DIY" kits from Guytronix - the 8 Watt EL84 based Ardmore ($299, direct from www.guytronix.com ), and the $249 1/2 watt (2 watt optional) Gilmore Jr.


First off, a couple of disclaimers. Normally, a reviewer obtains a "loaner" of the product to be reviewed, and return or purchase it at the end of the review process. In this case, we're dealing with a pair of tube amp kits, and as such, they can't really be assembled and reviewed and then returned in the same state as they arrived in. :) And since putting together a tube amp takes a certain amount of time and labour (stay tuned to this thread for an idea of exactly how little or much ;) ), and since that itself has value (IOW, the company can take the returned / completed amp and sell it for more than the price of an unbuilt kit), Rich at Guytronix and I negotated a deal where I would built both kits, do the review with complete freedom, and send back only one of the completed amps. That way, he doesn't profit from my build time, and I "pay" for whichever amp I decide to keep by the labor I put into building the amp I return. So right upfront, you know I'm keeping one of these two kits... and since these are Pro Reviews, you're all invited to participate and help keep things honest and above board. :)


There are many potential uses for a small, low power, yet toneful tube amp. Practice at home and recording purposes are two places where such amps are commonly used. In this review, I hope to cover the actual kits themselves, the build process and the difficulty level and experience / skills you'll need if you decide to build one, and what level of customer service and assistance you can expect to recieve from Guytronix. Additionally, we're going to fire up the studio and do some tracking of the completed amps so that everyone can get an idea of how these amps sound, with particular attention to how well they perform in a studio recording environment - after all, this IS a studio forum. ;):D But we'll also break out the SPL meter and see just how loud a 1/2 or 8 watt head really gets. That should be of interest to those who are considering one of these amps to use for practice.


What I'd like from you is your participation. Let me know if you have any questions. If something's not clear, point it out. If you have built one of these amps, feel free to voice your opinions about them and tell us about your experiences. Rich from Guytronix will also be participating and will be making comments and answering questions as appropriate as well. He's a good guy, and you'll find him easygoing, knowledgeable and helpful. :thu: I'll also be asking for suggestions regarding what you want to hear insofar as clips, and we might even try to set up an in-studio session (at my place) with a few of you to let you get some hands-on, in person playing and listening time with the completed amps. We can track some clips of your playing, and give you an opportunity to tell everyone what you think based off firsthand experience playing through the completed amps. If you're interested in participating in that part of the review, please let us know.


Ready? :)

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You are in for a treat- the kits from Guytronix are foolproof and complete. Absolutely no missing parts or problems. Great documentation and killer tone! I have demoed my 1/2 watt through multiple cabinets for some of the best ears around and everyone was blown away.

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Originally posted by danbomb

I actually knocked it out in 6 1/2 hours while drinking Jack&Coke! I could probably do one in 4 hours now that I have one under my belt. I used to work at Tophat in '98 wiring up amps.


Somehow I have a feeling your experience might make it a bit easier for you than the average Joe.:idea:

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In the past few months we've picked up a 10-watt Tech21 Trademark 10 and a 5-watt Epiphone Valve Junior. These low-powered amps are lots of fun :cool:


Any thoughts as to what type of speaker enclosure you'll be using, or will you build that as well?

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Originally posted by dougb415

In the past few months we've picked up a 10-watt Tech21 Trademark 10 and a 5-watt Epiphone Valve Junior. These low-powered amps are lots of fun

Any thoughts as to what type of speaker enclosure you'll be using, or will you build that as well?


Rich has some specific recommendations that I'll let him fill you in on. Here at my place, I have various different things available; some of them are speakers in other amps that I can jumper to for the tests... an E/V 12" in a Princeton II cab, a Fender blue label 10" in a Super Champ, a Marshall 1960a 4X12" with the stock 75W Celestions, the stock Fender Utah 12's in a '72 Twin, etc.


Guytronix has some optional head enclosures for the amp kits available as well, and that may also be a source for a speaker cabinet... Rich? :confused:

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So you make your amp kit order, and a few days later the box shows up via Prioity Mail - I was actually impressed with how fast that was. :)


Opening the box reveals an expert packing job. Everything is set in the box in an organized manner, and individual elements of the kit are wrapped seperately.




Pulling everything out of the bubblewrap and packing paper reveals this:




Again, you'll notice that everything is well organized. One example - polarized parts such as diodes and polarized capacitors are placed into a seperate bag - which is handy for old hands and new builders alike, since these parts require special attention to their orientation when they're being installed.

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To follow up regarding Phil's points of light, yes, the amp sounds very good with 4,8 or 16 ohm loads but seems to favor 16 ohms.


I've pushed the following speakers with the Gilmore Jr; 12" EV in a Mesa 1/2 back cab, 4x12 circa '73 Ampeg V4 with two ceramic Weber Blue Dogs up top and two ceramic Silver Bells down below, a 4x8 custom cab with two Weber Alnico 8A125Ts up top and two Alnico 8A125s down below, 4x12 1960A Marshall with 75 watters, 1x10 Weber Blue Pup, 2x8 combo with Weber Alnico 8A125 and 8A125T, 1x10 and 1x8 95% closed back cabinets from Marshall MG Series Mini/Micro Stacks.


My Favorites are the Weber 8A125s, 8A125Ts, 10" Blue Pup and the two Marshall Mini/Micro Stack (MG Series) cabinets with 'knock-off' Celestions in both 8" and 10". I am very surprised at how good those 'Far-East' speakers sound.


Although these are my favorites, the other configurations sounded very good too. For the most part, it is very tough to find a speaker that sounds bad with the Gilmore Jr.


Regarding enclosures and such; we will soon be releasing a combo cabinet that houses a 10" speaker that can be Customer supplied or a 'sound-qualified' speaker from us. Some time ago, we offered a new optical compressor as a prize-drawing for those who replied to an inquiry regarding what the Customer is looking for in a low-watt combo. We've taken all of the input and designed the new combo enclosure around those Customer thoughts. In addition, we have qualified a couple of enclosure/cabinetry builders to address Customer designed ideas. We are most happy to steer our Customers to those firms so that they can work out the pricing and details directly with the enclosure manufacturers.

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So now that we have the box open and we can see everything that's included, let's talk a little bit about what ISN'T included.


And the answer to that is really "not much". :thu: There's plenty of wire in the kits, and even the shrinkwrap is included, along with tubes and all the parts you need for the build. Actually, I was missing one or two minor things, but if you find something is missing from your kit, a quick call or email to Rich will get that taken care of in few days via priority mail with no questions or hassles. But pretty much everything you need to build the amp is in the kit, with the following exceptions:


You've going to need a soldering iron, desoldering tool (bulb or wick), some flux, maybe a tinning block, a pair of pliers or a nutdriver, a screwdriver or two, wire strippers and side cutters - basic hand tools. Oh yeah - a multimeter. You don't need an oscilloscope to build these kits, but a decent multimeter is a must have. I used one of these, and it worked fine for the job. pRS1C-2266866w345.jpg


Additionally, as you'll see in some of the soon to be posted pictures, a Panavise is a useful item to have around when working on jobs like this. I used this one:




You can get them here for about $20.


You're going to also need some solder. I used silver solder, but any good rosin core solder should work fine.


I was actually going to combine this review with a review of the Cold Heat (www.coldheat.com ) soldering tool... I actually ordered one, but it took nearly two months to arrive. :( And while I started the Gilmore Jr Build with it, I quickly grew frustrated with it. Frankly, it's a handy tool to have around for quick, lightweight soldering jobs, but it's just not up to the task of a build like this. Get a decent soldering station or iron - I used a Weller soldering station.


And as Rich alluded to, there is no speaker included with the basic kits. There isn't a traditional "cabinet" or head enclosure either, although two wooden end caps are included that will work fine if you're not going to be taking the head out to gigs or away somewhere to practice on a frequent basis. You can leave the wood bare, but a little stain and some clear coat will make them look better.


The on / off and standby switches are labeled, but other than that, none of the controls are labeled, nor is there any other labeling included in the kits. With so few controls, that's really not a significant issue, but if you'd like to dresss up your kit, decal and lettering kits that you can print out on your computer are available at most hobby shops.


Okay, everyone have their tools and supplies ready? We're going to dive into the actual builds... (drum roll please... ;) )

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The approach you'll likely take to doing the build is going to depend largely on your skill and experience level. While a seasoned pro can easily assemble these kits with just the color-coded wiring diagram, schematic, and maybe the parts list, I recommend that everyone check out the manuals. They are generally well written and make everything quite clear - even if you're not a grizzled vet with the solder scars to prove it. :eek:;)


The first step, after you get everything organized is to insert the various chassis mounted components. You'll need the phillips head screwdriver and the pliers (or nutdriver) for this. These parts include the potentiometers (volume and tone controls), fuseholder, IEC power receptacle, tube sockets, LED power indicator, on/off and standby switches, tube sockets, input and speaker output jacks, as well as the power and speaker transformers.


Here's a shot of the chassis with all of the above mentioned chassis mounted parts installed:




The next order of business is to mark the turret board. That's the light greenish board in the center of the chassis in the second picture on page one. As the manual points out, writing the pin numbers (as shown in the building instructions) directly on the board makes things much easier on you, avoids potential mistakes and confusion, and will come in handy when doing your final testing and troubleshooting - but hopefully you'll be able to avoid that last part. ;)


After getting the posts on the turret board marked (a fine tip Sharpie works well for that, but even a Sharpie will smudge if you wipe it too hard or too much), the next step is to attach several short wire leads to various pins on the board. The color of the wires really doesn't matter, although as the manual points out, a color code that corresponds to different destination types can make things a bit easier on you later.


Here's a shot of the Gilmore Jr board, being held in the Panavise, with the wires attached:




You should also be able to see that I used the Sharpie to mark the tube pins on the ceramic sockets - that's another useful suggestion you'll find in the manual.


All of this is fairly easy to do. A couple of notes and cautions though!


First of all, you should be careful whenever you are working with the transformers so that you do not put any excessive pull or strain on the wires. They're quality components (made by Mercury Magnetics - good stuff), and the most expensive items in the kits - so use caution and never "yank on the wires". When you're mounting the transformers to the chassis, guide them through the appropriate holes gently and with as little pulling force at the point where the wires enter the transformer as possible. And take care not to kink or pinch the wires between the chassis and the transformer housings.


Secondly, the transformer mounting holes at first may appear not to line up perfectly with the right holes in the chassis. Don't let that alarm you - a little pull on the outer mounting flanges of the trannys will seperate them far enough to reach comfortably.


Also, while we're at the point of starting to solder, a little caution is in order. If you've never built anything before, and never soldered, you could probably still manage to build one of these kits and wind up with a working amp... but it's going to be a challenge for you, and require a little extra work on your part. Get some scrap wire and parts (a broken radio can do for parts in a pinch), and do some practice soldering. If you don't know how, get someone to show you, or feel free to ask for help on this forum. :) Remember - always heat the work, and not the solder itself. Go slowly - this is a cool little amp you're bulding, and you want it to be something you can be proud of, right? ;) And a note on safety - solder is HOT and it, or the soldering iron can cause some pretty serious burns... so be careful. Use a good work surface, and not mom's (or wife's) bare kitchen table. Hot solder flows like water and drips like water, so if water would drip from the soldering point and land on you, chances are that sooner or later, so will the solder. And while we're talking safety, only solder in a well ventilated area, and avoid breathing the solder fumes. There's nasty stuff in there that you really shouldn't be sniffing - and no, it won't get you high, so don't even go there.


I think this is a good place to stop if you're takig your time (you should!) and doing it a bit at a time each evening.


A pro should have no problem doing all of this in under two hours... maybe even one. A beginner might need three. or even four. Remember - it's not a race... s/he who builds fastest doesn't win - it's s/he who builds best. ;)

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Nice Pics Phil! Great detail. What camera are you using?


Rosin Core solder 60/40 or 63/37 is very good to use. Since Phil was using silver solder, the flux was helpful. Flux is not recommended for novice builders as the flux, if used too heavily, can melt/run into the base areas of the tube sockets and cause issues. This is true with any electronic project. Phil has been soldering since the Chicago Fire. Don't worry Phil, we won't tell who started it ;^) :freak:

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