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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
jes45

Showing 6 responses by jes45

jes45 OP
293 posts
 
Update: With countless hours, the ST-225 is definitely fully broken in. As most TRL owners can attest, it takes a while to fully break in one of their pieces of gear or even just their digital mods.

The amp has opened up dramatically, most noted between 300 to 550 or so hours and the stage got wider and deeper as well. The low noise floor of the amp, along with the low noise floor of the TRL/SA-14, is unbelieveable. I can't believe how much noise we are accustomed to and just tune out. The amp can be at 95 dB levels (and higher) and be dead quiet between songs. When the music starts, it makes you jump the first couple of times, which I completely forget when guests come over. (Sorry).

Anyway, I couldn't be happier. And I am not upset with my decision to sell the Tube Research GT-200's ... a statement that I thought that I'd NEVER make.

Best wishes,

Jack Seaton
jes45 OP
293 posts
 
Kalen: To each his own. Since most of my listening is done in a very dim lit room, the whole numbers issue is void. Besides, I'd be embarrassed if I couldn't set the volumes by ear anyway ... it would be like owning a Porsche 911 and requiring a shift pattern on the gear selector knob. :) And, since we are on the topic of First Sound/Presense Audio, did you know that Paul Weitzel (of Tube Research Labs and Transistor Research Labs) designed the circuit for the Presense Audio active preamp? You have likely (like TVAD) been enjoying his efforts for years. :)

Oldpet: Sorry, Paul. I haven't dropped in here for a long time. And yes, I'm still enjoying the amplifier every day. Yesterday (Christmas) we had most of the Wife's immediate Family over. The Sister and Brother in Law stayed in our guest room which is adjacent to the listening room. The BIL knows that I leave gear on 24/7, so he pushed play on the digital player and listened to music for a while the other night. Being a former professional himself, (studio musician, acoustic guitar) he was amazed at the sound of the music. I found out later that he stayed up until around 2:30 AM listening to various discs. (Looks like we have another converted audiophile ...) Anyway, he asked prices, etc. and plans on setting up a system sometime this year.

All I can do is grin ...

Best wishes,

Jack

P.S. Clio09 is right ... I've been enjoying the music and haven't been checking in on this review, which is an easy thing to do with the ST-225. :)
jes45 OP
293 posts
 
Donbellphd: Cool. I have never owned a Ferrari, so I'll have to take your word on it. Which model do you have?

As for the TRL ST-225 integrated, at $5500, it should fit many budgets.

I've heard Tony's D-225 and I'm not shocked at your impressions. It is a very musical, accurate, detailed and dynamic amplifier. Stage layering and depth are remarkable.

Best wishes,

Jack
jes45 OP
293 posts
 
Tvad: I figured that you had to sell your Presence Deluxe II because someone told you not to own anything designed by Paul Weitzel ... :)

Kalen: I suppose this is a topic where we will have to agree to disagree. I'm the type of guy that doesn't require numbers to set the volume.

And yes, you are invited to hang out any time.

Humbly,

Jack Edward Seaton
jes45 OP
293 posts
 
Tony: Betcha didn't know that VTL's Signature series transformers were Paul's design that he did not want, so he released the design to Greg Scott, who later offered them to VTL.

And the Shallco 45 step attenuators used in my ST-225 were designed by Paul a few years back and built to his spec. Some of his ideas have trickled down to their other models.

And that the van den Hul "Copper Hopper" and Black Beauty were Paul's design, too.

There are a few others, but I'm not sure if they should be made public or not ...

BTW, I used to shift my 911S without looking at the knob, too. :)

Best,

Jack
jes45 OP
293 posts
 
Ellery911: It is a little "industrial", but I like it. The huge knobs really set the thing off. (You should have seen the Wife's friends with the big volume knobs, turning them back and forth ...). I do miss the 1" thick face panel, but at the price offset, I'll learn to manage. :) Especially considering the sound.

TVAD: I'm actually happy that they don't have numbers around the knob as an indicator. I would find that a little ugly, (think 70's el-cheapo reciever) in my humble opinion. I'm used to having step attenuators and have always used my hearing as Deb describes to set the proper level for each channel. It doesn't require much acuity, IMHO. And, if I do change the volume setting from one recording to another, it is easier to count off 2 or 3 clicks than it is to lower my eyes to look at indicator marks anyway. :)

Best,

Jack
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