Transistor Research Labs ST-225 Integrated amp

Review:

There’s not a lot I can say about Paul Weitzel and his contributions to high end audio, (Tube Research Labs, FIM Cables, Cable Research Labs, Fidelis Records and Diversity Records) that I have not already said over the years. I make no secrets of a heavy personal bias towards Paul's products and their reproduction of music which is, and has been, a revelation for me over the last 13 years of listening to music and gear.

Transistor Research Labs represents his latest contribution, along with his brother, Brian Weitzel of Record Research Labs. Together, they have made a believer out of a "tubes only" guy for the past 33 years.

I've owned various pieces of Tube Research Labs amps and preamps since meeting Paul at 92 Winter CES, where he showed with Avalon, First Sound, and Cardas with his huge GTRP-800's, which are 96 tube, 4 chassis, 1240 pound shipping weight amps that now retail at $140K. At the time, I owned Jadis amps (200's) and preamps, all heavily modified and Avalon Ascents. Since I couldn't afford the big amps that Paul took to CES, I bought a Stereo 100 Watt, which replaced my Jadis.

I've been working my way up the product line as finances allowed, and planned on settling on the GT-400's which retail for $85K. (Although I've seen them used here at Audiogon for much less).

My latest Tube Research amps were the GT-200's along with the GTP-4 line stage, which I replaced with the new Transistor Research Labs ST-225 (retail $5500).

Simply put, I no longer need to dream of the day that I can own (and have room for) the Tube Research Labs GT-400's. Paul has designed an solid state amplifier that doesn't sound like solid state, (and not like mosfets either). Typically, in the past, I have found that transistors are edgy, have glare, have a lack of high frequency dynamics, are not as holographic of imaging, and to be fatiguing. Solid state has always left me wanting to leave the room, rather than stay up late listening. Not the case with the ST-225 ... I don't sleep much anymore.

The ST-225 is dead quiet. I usually dislike power LED's or indicators, but am happy that they included a blue LED in the face plate. When the music starts, the ST-225 throws a deep, wide stage, with incredible focus and dark area around each instrument/voice. The dynamics really surprised me the most. In my opinion, micro-dynamics is where the heart and soul of music reproduction lies. The ST-225 excells here. Minute details are finally revealed. Musical information that has always been there is now evident. Macro-Dynamics jump right out at you, as they do in a live event, powerful and strong. Transient response is very quick and decay is very natural. Sonically, there is no fault that I can find. Compared to my Tube Research, I have found that I have been listening to, or have accepted tube hysterious effects or response for years. It's hard to describe, but once you experience it, it becomes really bothersome.

Weaknesses: I'm used to the 1 inch thick billet aluminum faceplates used on nearly every piece of Tube Research Labs gear that I've ever owned. I understand that the guys wanted to keep tthis new line of gear affordable, but I miss the nice, thick engraved faceplate. (Probably not enough to offset the price, but I've become accustomed to it). And, the amp is quite heavy (around 80 pounds) for a simple integrated.

Strengths: Seperate input selector switches for each channel (3 inputs each), custom made to weitzel's spec with silver contacts. Seperate 45 step attenuators custom made to Weitzel's spec with silver contacts. Cardas premium jacks (look like GRFA's) and Cardas posts (look like CCGR's). And, they use a Heineman circuit breaker switch for the power, no fuses.

I'm very happy. My new ST-225 is superior to the tube gear that it replaced and at a fraction of the cost. I no loger need the heat that 10 KT-88 outputs tubes/channel produce, along with the other 10 power supply tubes/input tubes. (on the GT-400's). Nor do I have to save for the 400's.

Sources used: TRL modified Marantz SA-14 and a TRL modified Scully 270 open reel, playing back 15 and 30 IPS 2 track production masters.

Speakers: Magico 3's

Cables/interconnects: FIM/CRL Gold throughout.

Room size: 23 X 12 X 8

Room treatments: Shakti Hallographs in the corners behind the speakers, along with custom made room treatment panels on the back wall, the side walls, and the ceiling.

Length of Audition: Around 700 hours of use on the amplifier.

Type of audition/review: Product owner.

Thank you for your time,

Jack Seaton