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JEL Loctal Preamp

Motivated by Ding's octal version of the 834P, I quickly got my hands dirty punching out and painting a chassis. 

Loctal tubes

The concept of this project was to build a full function stereo preamp utilizing loctal tubes based on the schematics below.

Preamp circuit
Power Supply

Tube rectified CLC power supply

Line Stage

Zero feedback single gain stage direct coupled to a cathode follower line stage topology featuring the two medium-mu triodes below



Phono

The stock EAR 834P circuit (above) used all high-mu 12AX7s with the second stage capacitor coupled to the cathode follower stage. While preparing this blog entry, I remembered that my dearly departed friend, mono aficionado BrianmonofantasticoClark, grafted his own interpretation of an EAR 834P phono stage to his SE 801 mono integrated amplifier. He was an active participant in this discussion of 834P modifications initiated by Thorsten Loesch.

Line Transformers Redux + Art Dudley + AQ Dragonfly Black

My boring digital life

Probably the most significant digital audio gear I ever owned was the Tascam DA-P1 DAT recorder. This machine recorded my recitals, chamber music performances and served as a back-up and playback deck for my CD projects from the mid 90s until the early 2000s. It was rendered obsolete when HD based recording became the industry standard.

I never invested in a high-end CD player. The most I ever did for CD playback was get an Audio Alchemy DAC in the Box fed by the digital output of a consumer grade Philips CD player. When the Philips CD player conked out in the early 2000s, it was replaced by a Sony DVD/SACD player.
Line transformers as Digital Sound Processors

Ever since I inserted a pair of Tamura 600:600 line transformers as a digital sound processor (DSP) between the CD player/DAC and my preamp line inputs, I didn't see the necessity of upgrading the Audio Alchemy DitB. I don't know if this holds water but my empirical rational for this is, magnetic …

November Hifi Show 2017

I actively participated in this annual event for nine consecutive years with my Harana/Tono/Setup buddies but will break the tradition this year. 😞 This is a must see for every audio/video enthusiast based in Manila. 👍👍👍 
more info

Grace G707 + Denon DP1250 = road less travelled

The 70s through the early 80s was the era of great development in direct drive turntable technology. It was only stifled by the introduction of the CD player in 1982 and to a minor degree by the revived interest in the classic suspended sub-chassis belt-drive system within the audiophile community.


Although I was exposed to some of the great direct drive turntables from the 70s, like the Luxman PD444 and the Technics SP10 MkII in a Mitch Cotter base in the home system of my late DIY audio mentor Tom Cadawas, I never had a direct drive turntable in my audio system till now.

This was probably due to the almost cult-like indoctrination inculcated by early 1980s Haymarket publications like Popular Hi-Fi and Hi-Fi Answers exalting the virtues of the 3-point suspended belt-drive from the land of kilts vs. the evils of cogging and servo hunting direct drive turntables from the land of the rising sun.


Even though the late Harry Pearson of TAS used a direct drive Goldmund Studio in his refere…

Grace G707 + TD150 = road most travelled

By the time I acquired a used Grace G707 tonearm ca. '83, it was already an up and comingclassic. Classic being a euphemism for affordable since TAS and Stereophile were already waxing poetic about heavier MC cartridges from Kiseki, Koetsu, Accuphase AC-2, etc, which required more massive tonearms. 

I had to do irreversible hacking to my thrift store-found ARXA turntable to mount the G707. All that effort paid off since the improvement this tonearm brought to my audio system was staggering - more transparency and definition throughout the audio bandwidth. The listening experience became a lot more enjoyable! Sadly, that G707 got lost in a maze of senseless upgrades I went through for the next ten years. I held a torch for this tonearm until I found another nice sample for this time travel episode.

70s MC cartridges  Back in the day, I could only afford the Audio Technica low output moving coil AT31E + Sony HAT10 MC transformers. Those two items are gone, so
 accompanying us on t…

JE Labs Simple 46

I've been hoarding type 46 power tubes gathered from radio shows I attended with my buddy Chong in the late 90s. Building an SE 46 amp was in my to do list when I packed up for Manila in '08. But things got in the way. Finally, after a round trip across the Pacific, the amp has come into fruition.

Given its designation, one would think that it is just a 45 with dual grids. However, aside from the UX-5 tube socket requirement, the 46 is notquite a 45. It only puts out 1250 mWatts, 750 mWs less than the 45's 2000 mWs. Maximum plate dissipation with grid 2 tied to the plate is 5.5W compared to 10W for the 45. Although it will perform very well loaded with a 5k primary Z output transformer, the textbook recommended load is closer to 7k, due to its higher plate resistance of 2380 ohms vs. 1700 ohms for the 45.



It's been over 20 years since the Simple 45/2A3 was uploaded to the now defunct DIY section of the old Angela Instruments website. So I wanted to reprise that old-sc…