" I just finished installing the GT-101. It replaces a Dynakit Stereo-150 in which I fried one of the channels. I also replaced the Pat-4 preamp with one in which I installed all your updates so far. Let me say that the sound is superb, better than before! Smooth comes to mind as well as taught, no ringing that I can hear. This is most likely due to the low IM distortion and of course the good damping factor. I doubt that I can hear Harmonic Distortion at these low levels, even in the previous set up with 0.5% HD or so I couldn't. The harshness in the sound that I associate with IM and crossover is not there anymore.
The assembly of GT-101 was straight forward, easier than the PAT-4 up dates even. Your instruction manual is excellent, better than Heath or Dyna. The quality of the parts looked to be very good with a very nice chassis. I am looking forward to additional Pat-4 updates. Hopefully with enough oomph in the last stage to drive 30-60 ohm headphones! "
"Hi Dan..Here is some feedback from a happy customer. I just finished my first GT-101 today. A lot of things have been delayed by our move to another city, but I finally got around to your kit about a week ago. It was a straight forward build if I just took my time and double checked as I went along. Anyway, late today I hooked it up to my old Dynaco speakers and was very impressed. It sounded great and gave me a new respect for the speakers which I had not tried in some time. I tried jazz, bluegrass and classical at high volume for some time and the amp never broke a sweat. It sounds great. I'm putting together a DIY speaker kit and both will go to my oldest daughter. Then I'll get going on the second 101 for another daughter. There may be two more after that.
I really appreciate your work and the pleasure the 120 rebuild and this kit has brought. Your kits and upgrades deliver a lot of sound and pleasure for the buck. I hope you continue.
An aside...just as it was testing for the 72 volts I bumped a nearby table with my back side and a book hit the floor. Like to have scared me to death! I just knew everything was going up in flames. Fortunately all was good and the dc voltage came in at 72. Thanks again for the good products and support."
"I ordered your GT-101 kit several weeks ago, and I'll never look at a soup bowl the same way again. Nor will I ever plug in an appliance without keeping my right hand in a pocket. Great kit! Great assembly manual! Great sound! Your advice to step away from the kit when tired should be applied to all lines of work.
Once I had assembled the kit, I started taking a closer at it. Much better inherent quality than the Dynaco kits. Take the case, for example. Dynaco: self taping screws. GT-101: integral welded nuts for the threaded and counter sunk flat head case screws. You can take apart the GT-101 case as many times as you like. No pointy corners on the GT-101 circuit boards because they've been trimmed plus you get real metal lined through-holes that do a great job wicking up solder. With a good quality soldering station tool, anyone should be able to finish those circuit boards so they look professionally assembled.
I took a few liberties with the kit. I glued in place the top run of each six loop output inductor with a few dots of super glue. Treated the assorted lugs with shrink wrap tubing to cover the solder. I used a guide pin to help install each of the three heat sinks after applying the white heat transfer paste. So, no mess anywhere inside the case. And last, I found that lining up all the resistors on a piece of white paper in the install-order from top to bottom on the paper really made things move along quickly."
"Finally got a chance to build the amplifier. Thanks for the enjoyable experience, the clear instructions, and the great value. It took about 8 hours and I work slowly and deliberately. It sounds great given the very reasonable cost. I know it would be a big project, but if you design a companion preamp, let me know. I would definitely be in the market for another fun kit. Thanks again."
So I have been listening for the last 2 evenings to this amp. It is a good sounding amp. If this was the only amp I could have, I would have no regrets assuming the speakers were appropriate. The price/value ratio and the extensiveness of the kit are tough to beat. The closest ClassD can come is around $385 before shipping ($185 for their 60wpc kit + $200 for their case with all bits). I'd like to hear them back to back. I have given it the thumbs up to the folks I know who were interested. The other components were:
I have since tested the amp with Large Advents, which the Akitika drove quite well.
"Dan, good afternoon. Just to let you know that I finished the assembly of the GT-101 today. Power supply tested at 71.4 VDC and speaker binding posts testing performed very well. I played some music in the testing jig I assembled with some small high quality speakers I have here and the equipment performed excellently.
Of course, I do not have specs testing equipment such as frequency response, power output, channel separation and all that crap. But my ears are still working fine and the heat sinks were slightly warm, which of course is normal due to the volume I was playing the speakers, but the prognostic performance is of a very stable, very well designed, high quality components and the assembly manual is impeccable.
Of course, there are tiny details such as –for a person, novice, who needs these, of course-- when the instructions for connecting and soldering the black and yellow wires from the transformer into the X1 and X2 at the Power Supply board, something could be said to the effect that either of the two colored wires [black and yellow] can be connected and soldered into any of the two connection sites [X1 and X2). Just a comment, though, nothing serious.
But, to be honest to you, I believe that this kit will be a success and you will be selling a lot of those. The cabinet is very simple and functional, but precisely accepts every bolt and board at its exact place very beautifully. As soon as I have some funding, I will very probably order another kit...
In short: This extraordinary equipment, very reasonably priced was a lot of fun to assemble it. I really enjoyed working it."
"I finally had a chance to get to the GT-101. In short a beautiful and very high end execution of some wonderfully updated classic design insights. I have included some photos of the build. Excellent components and well-conceived isolation, and amplification. I have changed some cable routing and star ground a bit but all very minor tweaks...beautiful sound, great S/N ratio, quite transparent. Congratulations."
"Disclosure: Aside from being an electronics genius and a nice guy, Dan Joffe is my cousin. All the same, I call them like I hear them. I have been tinkering with speakers for about a dozen years and also build high end interconnects. I take audio seriously, probably too seriously, but I digress.
Many reviewers speak in the arcane secret language of audiophilese. They define performance using words to represent concepts that are not clear. Moreover what sounds good is subjective. So, instead of reviewing gear with words like sibilance, attack, decay, tempo, sheen, airiness, flatness, punchiness, etc. I ask a more basic question. Does the damn sound coming out of the speakers sound like real music? You will never hide the Lincoln Center Orchestra in a pair of speakers, even really big ones, but I think you get the drift. Certain instruments tend to be particularly telling on the quality of a system. To my ear piano, violin, brass, and the female voice tend to represent a solid portion of what separates good gear from excellent gear.
The GT-101 has a very nice musical nature. It sounds even top to bottom, not favoring or limiting any particular frequency range. One of the criticisms of the original Dynaco solid state amps was that the high end would get a bit shrill. This is not the case with the GT-101. I listened at all volumes from low through ear-bleed and the high end remained detailed and musical. One of my reference tracks is Take the A Train performed by the Lincoln Center Orchestra. The piano in the opening has a wonderful reality about it and when the brass kicks in later it just sounds right. The sound is textured as in a live performance and the instruments remain distinct, not blended together in a music mash up.
The GT-101 held its own compared alongside several other (more expensive) amps I auditioned over the same time frame. For its very modest cost it is a steal. I would recommend the GT-101, not just to Dynaco junkies, but to anyone who appreciates good music and excellent value.
Building the GT-101 kit was fairly easy for me and it worked right out of the gate. Again, disclaimer, I have quite a bit of experience assembling amplifier boards so it was not a new experience for me. I have built several other kit amps in the past few years. The quality of the provided directions with the GT-101 is just far and away the superlative winner. Read the next sentence carefully. Any patient person with steady hands, a $10 multimeter, and a $5 magnifying glass can successfully build this kit."
Rob from Oregon:
"...the next track utilized is from Genius Loves Company (Concord CCD-2248-2). Fever (Track 5), with Natalie Cole, was recorded just prior to the passing of Ray Charles. There is nothing particularly smooth about Ray's voice at this point in his life, and the track provides a wonderful counterpoint to the ethereal quality of Ms. Cole. Think of is as sandpaper vs. butter. The updatemydynaco mod effortlessly captures the essence of this contrast of vocal age, style and timbre...In the final analysis- any piece of equipment should at best never call attention to itself, but in an unobtrusive way draw you into the music. Does the updated ST-120 accomplish such a rare feat? In a word, yes..."
Chuck from New York:
"...I put both of the new boards together yesterday, and enjoyed it very much - the boards are really nicely done, and stuffing them is quite simple the way it's laid out. Hard to make a mistake..."
Rick, who has updated two Stereo 120's, says:
"You have a very nice product. The assembly instructions are excellent. Building the kit was easy. Take your time. Follow the instructions. Read them again if you don't understand the first time. The information one needs is there. Your timely answers to my emails were very helpful. The finished amplifier is better than the original. It was a fun project."
Bill from Florida:
"...What an easy kit to put together. Your manual is perfect! I have done a ton of kits in my life and this one was the easiest I
have done in awhile. I may end up getting the power supply retrofit in the future, but, so far, everything is running fine and cool.
No hums, hissing, buzzing.....nothing but music!!
Thanks again for your help and advice.
"It started when I discovered that one channel of my Dynaco audio system was
inoperative. Seeking a solution, I came upon Dan's web site via a Google
search of “dynaco". After disassembling the stereo 120 amplifier, and many
emails to and from Dan, I (we) discovered that several components in the
power supply had failed, resulting in 96 vdc frying one of the audio boards.
Dan's super heat sink, updated board seemed the ideal solution for me, a
diy-er and hobbyist, especially since I had assembled the amplifier, PAT~4
pre-amp and FM-3 tuner from kits back in 1968.
The materials included in Dan's kit are first class; the board is of excellent
quality and design, with plated-through holes for components, and the silk
screen circuit and component diagram is sharp and clear. With Dan's excellent
instruction manual guiding every step, it's very difficult for ANYONE to make
a mistake. The cost at $109.00, including shipping, for the super heat sink
version is more than reasonable - at $89.00 for the non-super heat sink kit,
it's a steal, especially compared to other rebuild offerings on EBay.
Finally, the quality of the sound coming from my “new” audio system is superb-
I think it's better than the original."
"...Thank you for making this kit available. I have already built the kits and installed them... I love this old amp again!"
"I took the new "Dynaco-Akitika Stereo 120" for a "road test" yesterday - played Saint-Saens Organ Symphony (CD) at about max listening volume for about 40 minutes - the house shook, wall hangings were vibrating, but the amp didn't even work hard. It got a bit warm around the heat sinks, but not so warm that I couldn't keep my fingers on it. Amazing......just thought you'd like to know this. Bravo!"
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