Photos of LDA builds
Prototypes
Prototype #1
This is the first, 200 Watt / 4 ohms prototype, which was made utilizing the transformer and heatsink of a defective Onkyo TX-SV525R amplifier. The first PCB version, LDA192, is in it, plus you can see the power supply with the solid state relay as well as the APBM protection circuit in the 3rd photo.
Prototype #2
A 2x110 Watt / 6 ohms prototype, which was made utilizing the transformer, power supply, and heatsink of a defective Onkyo TX-DS656 amplifier. This is still built on the LDA192 PCB, but it contains the modifications deemed appropriate according to the experimentation and measurements. The later LDA162 PCB has these modifications. It contains a temperature controlled fan and a protection circuit with mechanical relays.
Prototype #3
A 2x70 Watt / 8 ohms or 4 ohms prototype, which was built on the LDA162 PCB in the chassis of a defective Yamaha HTR-6230 amplifier, utilizing its transformer, power supply, heatsink, and protection relay.
Prototype #4
A 2x100 Watt / 6 ohms prototype, which was made utilizing the transformer and heatsink of a defective Onkyo TX-SV545 amplifier. It contains the LDA162 PCB, plus you can see the PS1S power supply and the SPRS turn-on thump muting circuit.
Prototype #5
In place of the LDA192 PCB of the first prototype, the newer LDA172 PCB was populated and installed, other things remained the same.
Prototype #6
The #5 prototype felt lonely being the only mono prototype, so I made another similar, 200-Watt one with the newest amplifier PCB, the LDA17. There is only a slight difference to the LDA172 PCB, but I deemed right to test it, too, before I offer it to other people. Test results are the same as with the LDA172.
Builds by other persons
József from Tápióbicske, Hungary (May 2020)
József is the first person, who sent photos and comments after successfully building the LDA amplifier from the LDA172hc kit. He built the amplifier to lower than maximum power with lower supply voltage and used the SPRS turn-on thump muting circuit. He designed and built his own power supply. He commented on the result as follows (translated from Hungarian),
"Powering up is very simple, easy to set up based on your instructions. And most importantly: the sound is very good ... What I really like about your amp: even late at night when I'm listening at ultra low volume, it has the deep bass, it even has dynamics in it, but it doesn't become harsh at higher volume levels either. So a very well done product. I used to have quite a few commercial amps, but they all ended up in the trash. Well they weren't in the high end category, but they came from reputable manufacturers like Marantz."
Attila from Szolnok, Hungary (February 2021)
Attila built his amplifier using the LDA MIN kit components, but he bought the 120-Watt LDA17hc instead of the 80-Watt LDA17mc. The amplifier PCB version was LDA17 mk2 which is only different from LDA17 in an insignificant detail.
Attila listens to Monitor Audio Bronze loudspeakers. This is what Attila wrote about the listening test (translated from Hungarian),
"The sound is absolutely superb, I simply take delight in it. I'm just listening to Havasi with my wife, she really likes it, too. It sounds nicer than the Hood. I think it deserves a professionally looking enclosure."
Tamás from Tószeg, Hungary (February 2021)
Attila liked his LDA17 mk2 amplifier so much, that he put together another LDA MIN for his friend, Tamás. He also bought the 120-Watt LDA17hc instead of the 80-Watt LDA17mc.
Tamás listens to Dali Concept 2 loudspeakers, in which he upgraded the crossover with better components. Tamás doesn't care much about the looks of the amplifier chassis, but he commented on the sound of the LDA17 mk2 like this (translated from Hungarian),
"About its sound: Very clear. Compared to my other amplifier, which is a JLH clone powered through a particularly good quality 6SN7 tube, I feel like a curtain has been pulled back in front of me. There is no coloration in its sound, it simply comes through what the source provides. The depth of space has increased, the musicians are much more realistic, the vocals are crystal clear, free of any artificial build-up. The bass is accurate, well controlled, it doesn’t boom in the upper bass range, which is the fault of many commercial amplifiers. The highs are crystal clear. A real instrument. What’s still awesome in it is that its sound is extremely detailed, I hear as the fiddlestick slides along the strings or as the skin on the Japanese drum vibrates. So, I’m maximally happy with it, and again, I'd say it measures up to commercial amplifiers in the 1 to 1.5 million HUF (about 2800 to 4200 EUR) range."
József from Budapest, Hungary (March 2021)
József is an experimental builder who made a stereo headphone amplifier from two PCBs of the LDA172. This required a small redesign so that the voltage gain be only 5 times. As it turns out, the distortion and noise of the LDA amplifier is so small that it holds its own in this use as well. József built a regulated +/-14 V power supply for the amplifier.
József listens with an AKG K701 headphone and wrote this opinion (translated from Hungarian),
"I brought it into the small room and connected it to the preamplifier and the DAC in front of it. Phenomenal. Total silence and dynamics. Very appealing sound, superior."
Tibor from Vecsés, Hungary (December 2021)
Tibor bought 2 LDA17hc's and made the power supply for his amplifier himself. He gave a short feedback as follows (translated from Hungarian),
"A few words about the amp, better than the QUAD I had built before (thank God), have more 'life' in it, its lows are more beautiful, it's dynamic, and maybe even clearer, in a word, it is AUTHENTIC."
Guglielmo from Udine, Italy (January 2022)
Guglielmo is the first non-Hungarian who has built the LDA MIN. He posted his opinion on diyaudio.com as follows,
"I have built your LDA MIN slowly but with great success. At the moment this is my favorite, it sounds really great. It made me forget many previous diy amps I've made including many that have appeared in these [diyaudio] forums. Congratulations, maybe in the future I will get advice from you also for speakers. Thank you."
Einar from Stutensee, Germany (March 2022)
Einar is an Icelander, who lives in Germany with his family. He has also successfully built the LDA MIN.
Einar listened to the amplifier on Infinity Beta 50 and KEF C10. I received the following opinion from him,
"But the most important thing; the sound is amazing. I kept in mind your advices concerning the cabling to avoid distortion but was expecting some problems with grounding and noise, but there is absolutely nothing at all. I compared the amplifier with two amplifiers that I have, a powerful Harman/Kardon AVR in stereo mode and a 37 years old A&R Cambridge Alpha amplifier by using smaller KEF speakers as well as large Infinity front speakers of my surround system. I must admit that I had goose-skin listening to Tori Amos clear high voice in Way Down and the powerful bass of Phil Collins In the Air Tonight. And my son likes it very well and has started using it composing his music on his computer. And now I need to worry about making another one for my daughter ;-).."
Attila from Szolnok, Hungary (November 2022)
Attila sold his previously built amplifier based on the LDA MIN kit and built for himself an LDA17 amplifier version based on the LDA MID kit, i.e. with solid state relay protection circuitry, in a professional looking chassis.
Attila listens to Monitor Audio Bronze loudspeakers, and this is what he wrote about his experience (translated from Hungarian):
"Finally finished the LDA MID. I'm very happy with it and it's currently in the burn-in phase. I have set the quiescent current to 18mV, as the amplifier box is made entirely of aluminum, so it is very well cooled. I was kind of on pins and needles about whether it was worth investing so much money to build another version when the two output stages are basically the same. I wondered if it would sound different, I wondered if it would sound better than the LDA MIN. I dare say it did.
What is striking at first is the depth and power of the bass. I suppose it's the four buffer capacitors. The sense of space has also increased (I don't know why), I get the feeling as if the speakers are at least a meter further apart. The musical fidelity and clarity is also perfect. The previous amp had only one input, so different sources were fed into the amp via a Yamaha CD-NT670D using its AUX input, now there are four different inputs. It is likely that this has also affected the sound quality in a positive way. The routing and volume control has full remote control (everything can be controlled manually as well). It is a high quality unit ordered from China, which does not interfere electronically with the quality of the input signal. The potentiometer is a high quality Japanese ALPS 27. No hum is audible between tracks, no matter how much I turn up the volume, it's dead silent."
