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kateatahealthyrate-blog1 · 6 years ago

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AkitikA GT-102 review

buyers guide for iphone An e-mail from an old audiophile pal: “Herb, my buddy owns a recording studio, and he told me one of his $10k reference amplifiers stopped working and the manufacturer said it would take months to be repaired. So he went online and bought this 60W AkitikA solid-state amplifier to use while his big amp was being repaired. The trouble is, the kit cost only $314. (The studio guy bought his assembled and tested for $488.) Now, he likes the AkitikA more than his broke-down reference amp.” My friend wondered if I wanted to review the AkitikA amp (the name is a palindrome, based on a kit). “Hell yes!” I told him. “Kits are my roots!”

When I was in high school, my best friend was a radar technician for the Navy. He taught me Ohm’s law, and how to solder, dress wires, and use a multimeter. He practically forced me to build a Dynaco1 Dynakit Stereo 70 tube amplifier, as well as the matching PAS-2 preamplifier and FM-3 stereo tuner. I didn’t want to take tubes to college, so I also built Dynaco’s solid-state PAT-4 preamplifier and Stereo 120 amplifier, which I used to drive Dynaco’s A25 loudspeakers.

Oh, how I loved them. To this day, Dylan and the Doors have never sounded better! After moving to New York City, I built a solid-state Hafler DH-101 preamp and two (!!) DH-200 amplifiers, which I used to drive stacked pairs of Large Advent loudspeakers. Yahweh, Bob Marley, and The Specials loved this potent lively-up system as much as I did. Next, I started reading Audio Amateur and Speaker Builder magazines, buying used test instruments, and modifying my Dynaco and Hafler gear. By the late 1980s I’d advanced to building simple tube amplifiers from scratch, using parts cannibalized from antique radios. (I worshiped at the Philco 16B Tombstone.) Solder fumes, wire strippers, and building amps remain very appealing to me. For me, kits were the start of a new life one that led me to secret societies and darker corners of the audio underground. When I asked John Atkinson if I could review AkitikA’s GT-102 power amplifier, he said okay, but suggested that, because he would be testing it on his lab bench, I should request the factory-assembled, pre-tested version ($488). Which I did.

Description

Because the GT-102 is available as a kit I begin my description of it by quoting AkitikA’s “Satisfaction Guarantee” for this US-made amp:

Buy the kit.

Build the kit.

Listen to and enjoy the kit.

If within 30 days of receiving the kit you aren’t satisfied, return the kit. So long as your kit is correctly assembled, we’ll refund the price you paid, you just pay return shipping.

The GT-102 is a class-AB, 60Wpc stereo power amplifier in a case made of relatively thin steel. Its front panel sports only a logo and an illuminated, bright green plastic rocker switch for power on/off. On the rear panel are only an IEC power-cord inlet, two gold-plated RCA jacks, and two pairs of generic speaker binding posts. The GT-102’s interior is spartan, but studying its layout gives the potential kit builder a good idea of how much screwing and soldering will be required to build it.

The first thing to note is the steel wall separating the audio circuitry from the toroidal mains transformer and regulated power supply. Note the three deep-finned heatsinks: one behind the rear panel, for the power-supply regulator, and two in a row along the inside of the left side panel, one per channel, to cool the two LM3886 power operational amplifiers.

Now, before you get your knickers in a knot about an “audiophile-grade” power amplifier based on a lowly opamp instead of this year’s fashionable MOSFET, JFET,SIT, or bipolar device—you must understand that the AkitikA’s LM3886 op-amp is notorious and fashionable. The roots of the storied LM3886 can be traced back to 47 Laboratory’s 4706 Gaincard integrated amplifier, designed by Junji Kimura, which I reviewed for Listener magazine; Robert Deutsch reviewed it for Stereophile in December 2001.2 The Gaincard, introduced in 1999, had only nine parts per channel, short signal paths, minimal power-supply capacitance, and, with only one of 47 Lab’s Power Humpty power supplies, cost $3300 (a second Power Humpty cost an additional $1800).

The 4706 Gaincard’s high price, radical simplicity, and unorthodox power supply spawned concern among measurements- oriented audiophiles, but word quickly spread about how musically satisfying it could sound. After reviewing it, I bought the Gaincard and used it every day for 10 years with a pair of Rogers LS3/5a speakers. I’ve subsequently compared my Gaincard to one of its clones and one DIY version, and learned that all LM3886 op-amps are not created equal.

In using power op-amps, implementation is key. PCB layout, wiring routes, grounding strategies, heatsinking, power transformers, and especially power-supply design, will affect stability, transparency of sound, and the ability to drive speakers. My listening for this article, and what I see inside this amp, suggest that AkitikA’s owner and designer, Dan Joffe, has done a smart job with this LM3886 implementation. Kit builders should know that each of the GT-102’s three circuit boards is fitted with a lot of little parts, most of them resistors whose coded stripes identify their values. To build a GT-102, each tiny bit will need to be found, positively identified, properly positioned, and soldered to its board. (I recommend soldering no parts until each PCB board is stuffed full, in mechanically sound fashion.) That done, the rest of the assembly consists of bolting and screwing the boards, binding posts, power switch, ground lug, and power transformer to the GT-102’s chassis. I suggest working slowly and patiently while breathing fresh air (it’s best to solder in a place with good ventilation), and triple-checking each step. The minimum tools required for assembly are: a 30W, pencil-type soldering iron; a small sponge; fine (0.032"), 60/40 rosin-core solder; wire cutters and strippers; #1 and #2 Phillips screwdrivers; needle-nose pliers; a set of basic nut drivers; an inexpensive digital multimeter, to cross-check resistor values against your reading of their color codes; good lighting; and a magnifying glass.

AkitikA’s website says that assembly should take about eight hours, and that 97% of all first-time kit builders complete the GT-102 without a hitch. The remaining 3% get it right in the end, with a little easy guidance from AkitikA. I studied the assembly manual and found it exceptionally clear and idiot-proof.3 It looks just like a Dynaco or Hafler manual.

Listening

I cooked the AkitikA GT-102 on my workbench for three weeks, while writing the Follow-Up on Joseph Audio’s Pulsar loudspeaker elsewhere in this issue. The system I used with the Pulsars comprised Mytek HiFi’s Manhattan II DAC, and Pass Laboratories’ HPA-1 preamplifier and XA25 power amp. I thought this was the most balanced and spatially descriptive system I’d assembled since I began writing for Stereophile in 2014. Jeff Joseph, of Joseph Audio, heard it and approved. So did John Atkinson. Stereophile’s videographer Jana Dagdagan and I made a binaural video of its sound so you can experience it, too.4 I played this setup every day and never once questioned its verity, charm, or competence. It sounded so detailed and lively that I had zero motivation to swap out the XA25 for the GT-102.

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jbkerkhoff · 5 years ago

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Vinyl Records are still interesting . . .

After upgrading a Dynaco Stereo-80 and restoring a Stereo-120 power amp, I starting thinking about the old days — when all that was needed was a turntable, a stereo amplifier and some speakers to enjoy a record. It had been years since I had done any serious listening to my vinyl collection. Then I began having conversations with a friend who had a very extensive Jazz and Classical vinyl collection. As we talked, the old desire was re-kindled and, with his encouragement, I began to haunt flea markets and old book and record stores looking for vinyl treasures. I still had a decent turntable, and had recently upgraded the cartridge, but my phono preamp was at least 10 years old and not the best to begin with. It sounded ok, but the next logical upgrade was a more serious audiophile phono preamp.

The Hunt for an Audiophile Phono Preamp

As I looked around, it became clear that it’s easy to spend a lot of money on a phono preamp. I really wanted a tube model, but the choices were either way more than I wanted to spend, or very inexpensive models from China. They might be fun to try, but maybe not this time. Then I remembered: the same company that had sold me replacement parts for the Dynaco stereo amplifiers also sold kits. Their online store, Akitika.com listed power amplifier and preamplifier kits. They looked promising and a kit would be fun to build.

Photo Preamp – assembly

Akitika sells a complete, stand-alone, phono preamp kit that includes the preamp, power supply and case (about $250 + shipping), but I wanted to make a custom version, and thought I could build the case and power supply myself. The phono preamp board was $80 (including shipping) so I bought one. It arrived in just a couple of days, but with the holidays and preparing a course I was teaching in January, the project had to wait. I opened the box to look at parts and instructions, and they looked great — I was really looking forward to it.

Assembling the Preamp Circuit Board

Done in about 6 hours!

By early February, I was ready to start. The assembly order made sense, with the smallest parts added first and gradually working through larger ones. This really helped, since it is a crowded board and the larger parts would have made the smaller parts harder to install. The instructions were excellent, with check boxes to account for each group of parts as they were installed. The tiny capacitors were the biggest challenge for my aging eyes, and magnifying glasses and a capacitor checker were helpful to identify them. Working carefully, I had the board finished in about 6 hours.

Now we need a power supply

The finished power supply circuit board

The preamp requires regulated plus and minus 12-volt power supplies. The assembly manual for the complete phono preamp kit showed a recommended schematic, and it was similar to analog supplies I’ve built before. One new wrinkle: the use of a toroidal transformer. Compact and self-shielding, they are clearly better than the standard open-frame transformers I’ve used before. But where was I going to get one of those? As I looked around the Internet, I finally checked on Amazon, and, to my amazement, they had the perfect transformer. Not too expensive at about $26, I had one on order in no time.

Being an avid electronics experimenter, I had many of the other parts on hand. Compared to the 1970’s when I first began building projects, parts have gotten relatively cheap — especially when bought in assortments. Kits I already had provided most of the parts needed for the power supply:

Blank PC Board Kit with Headers and Terminal Blocks

Three-terminal Positive and Negative Voltage Regulator Kit

Electrolytic Capacitor Assortment

Monolithic Ceramic Capacitor Assortment

I also needed a few other parts:

3300 uF Electrolytic Capacitors

1N4007 Rectifier Diodes

.01 uF @ 400 Volt Capacitor

Detail of complete power supply

It’s worth pointing out that all of the Amazon links provide larger quantities than are needed for the power supply build. I view it as building my parts stock. With only a few parts used out of each assortment, the cost for the power supply board is less than $6. A well-stocked junk box may yield many of the same parts.

A Few Parts for the Chassis

Boards and transformer mounted

The PR-101 assembly manual also provided a layout. I decided to build the preamp in an aluminum chassis with a lid on top. This would make it easy to adjust the cartridge loading, frequency response and gain jumpers on the preamp board. Using the PR-101 assembly manual as a guide, I would need a few more parts:

Aluminum Chassis – 10-inch by 8-inch by 2 1/2-inch

Aluminum Chassis Cover

Brass Hex Standoffs

Switch, Fuse and Power Socket

10K Audio Taper Stereo Pot

Gold-Plated Phono Jacks

Blue 3 MM LED and Holder

Total cost for the chassis and hardware: $55.45. Again, some of the purchases, like the standoffs, LED and LED Holder, and Phono Jacks came in assortments. More back-stock. All together, the total cost of the project was under $150.

Building the Chassis

Completed preamp with power supply shield

Careful layout goes a long way towards making a neat finished project. Metal work has never been my strong suit, and I was determined to take my time. Back in the day, I lacked many useful tools like an automatic center punch, a drill press and burr removers, so this time, I thought I could do it well. Leaving the plastic coating on the chassis while laying out and drilling holes minimized scratches and dirt on the chassis surface. A metal nibbling tool and some metal files made short work of the irregular hole needed for the power switch/fuse/power cord jack. I think the finished project looks pretty good, and I plan to dress up the chassis with some paint or vinyl covering after I’ve tested it a while.

But How Does the Audiophile Phono Preamp Sound?

Heatsinks added to regulators

I couldn’t remember when or where I got my old phono preamp — I had had it for years. The Technolink TC-750 sounded fine for an under-$50 device, but I hoped that the new preamp would be noticeably better. The Akitika documentation said it would be dead silent with no signal, and it was. Was it even working? I started a record, turned up the volume control and the music began to play. I was playing a London recording of the Vienna Phil playing a Schubert Symphony (CS6772). I sat down in the “sweet spot” to listen and noticed immediately that individual soloists were more precisely located in the stereo field and the overall placement of the orchestral sections was clearer. I was noticing musical details that I hadn’t heard before. The top registers were more crystalline and the percussion was more crisp. A very good first impression. One final touch: I noticed that the voltage regulators were getting a little warm, so I added couple of homemade aluminum heat sinks. Complete with silicone grease.

I’ve got a little more tweaking to do with the various preamp settings, but I would have to say I’m pleased. Getting to know this new sound is going to be fun!

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Front of the complete preamp

Rear view of the completed Audiofile Phono Preamp

How To Build a Great Audiophile Phono Preamp Vinyl Records are still interesting . . . After upgrading a Dynaco Stereo-80 and restoring a Stereo-120 power amp…

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