knotscott's System

by knotscott on
My system and room
My system and room
Wife's living room with speakers crammed in the corners
One of the Dyna/VTA monoblocks with EH6550 output tubes
Transmission line speakers
Tube preamp
Wife approved DIY entertainment center
B&K ST-140
Right side monoblock with 7581A output tubes
Left side monoblock with 7581A output tubes
Sansui SR1050 w/SAE
Modded LP120X w/Nagaoka MP150 and JN-P500 stylus
Custom DIY TT w/Marantz tonearm
Dyna70/VTA amps with 7581A output tubes and solid state copper rectifiers
early morning blue glow of the 7581A tubes

Description

My system has a lot of poor man's high end and DIY touches.  The speakers, preamp, and main tube amps have been part of the system since around 1990, but have undergone several upgrades and refinements since.  If I can't build it, I usually buy an affordable piece and upgrade or modify it myself.  I've had my hands inside most of my system, including the DAC.  It's a great way to get better gear than budget allows, and gives me a better understanding of what's inside and how the entire chain works.  

I've had the good fortune of having Bobby Palkovic from Merlin (RIP), and Ken Stevens from Convergent (CAT) as friends and audio mentors since the mid 80s.  I worked with Bobby at Merlin while they were in Rochester, and met Ken through him.  We did many CES shows together from the mid 80s to early 90s.  Exposure to the insights of these two brilliant minds, plus exposure to the level of gear they were surrounded by has been immeasurable to my audio journey.  No doubt my system would be different today had I not met them.  This system was good enough to make me happy 30 years ago, and has slowly improved with refinements over time.  

In 2023 the system got reconfigured into a tube/SS hybrid bi-amp configuration, and I've continued to improve on that configuration since.    In 2025 an older BK ST-140 amp was added to power the main woofers.  An active crossover was added as low pass only to limit frequencies above 63hz to the amp, and the original passive low pass filter has been bypassed.   Cost for the amp and active crossover weren't much over $125, and have resulted in significant improvements on multiple levels (IMHO).  The tube amps got an inline high pass filter in 2025 also, which made another very notable improvement in overall clarity.  
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Room Details

Dimensions: 24’ × 20’  Large
Ceiling: 9’

Components Toggle details

    • DYNACO/VTA tube / B&K ST-140 SS Amps (Twin Dynaco 70s used as mono blocks w/VTA boards & BK ST-140 SS amp - biamped)

    My first Dyna amp was a Dynakit 70 that my uncle built in 1964.  He gave it to me in the late 80s.  I acquired a 2nd Dyna factory wired ST-70 a couple of years later.  A friend beefed up the power supply caps a bit, refreshed some caps, and I used these as one-sided monoblocks for 20 years...they replaced a very good Distech LS-2 amp (which is essentially a modified B&K ST-140).  

    The amps got rebuilt in early 2020 with the VTA circuit boards, new quad caps, new Convergent audio coupling caps, new tubes, and I wired them in a passive vertical bi-amp configuration.  Later on, I removed the tube rectifier and replaced it with a SS diode plug-in, and put it all on a variac to reduce the impact of inrush current.  After some trial and error with several tubes and configurations, I ran Gold Lion KT66 outputs for about a year, then settled on the Tung Sol 7581A (a 6L6 variant), RCA 12AU7 clear tops, and Sylvania 12BH7a as driver tubes, and am running each amp as monoblocks, using only one side of each amp, which allows some additional tube choices.  

    In 2023, the bi-amp configuration went from vertical/passive to vertical/horizontal, active/passive, tube/transistor hybrid using the tube amps on the midbass and treble, and a Kenwood integrated to power the woofers. 

    As of 2025 there's now a BK solid state amp powering only the 8" kevlar woofers in the transmission line of the speakers, which runs <63hz with an active low pass crossover, and also feeds the high level inputs of an active self-amplified Definitive Technology Powerfield 15 subwoofer that runs < 50hz.  After adding the active low pass filter, I installed an inline high pass filter on the tube amps @ ~ 63hz....another very notable improvement.  It lets the tubes handle the whole vocal range, and leaves the SS amp to control the movement of the woofers....best of both worlds.

    Edit July 2025 - A B&K ST-140 has replaced the Kenwood amp to drive the woofers below ~ 63hz.
    • BK Labs Inc. ST-140
    This is an older B&K ST-140 I picked up locally to power the lower octaves of my rig.  It replaces a smaller and even older Kenwood KA-3500 in July 2025
    • Lazarus Cascade Basic Preamplifier

    I bought this new in the early 1990s from Paul Heath Audio.  Very nice sounding reasonably priced tube pre-amp in its day (~ $600).  I freshened it up with new Convergent caps, new resistors, and new tubes this spring.  It's been a fine sounding piece, and love the low profile look with the bold red lettering on the black face.

    • Sterling Acoustics Acumen II

    These were made by my small company in Rochester, NY around 1990, and are the heart and soul of my system. They were the culmination of years of being in business and around the business.  Focal 8K kevlar woofers in a transmission line, Focal 5k midbass with an aperiodic chamber that dumps into the transmission line, modified Seas tweeter, proprietary crossover with top shelf components.  The crossover has it's own chamber, is wired with Kimber Kable teflon coated OFC copper, Litz wire inductors, Convergent Gen 1 caps, non-inductive resistors.  It took a long time to dial in the crossover values before I moved them inside the speaker.  Each driver has its own solid copper input. 

    I sold off my Merlin 4 speakers more than 30 years ago to fund the parts for these, and have loved them since finalizing the crossovers.  They've continued to reveal every component or configuration upgrade I've made.  They pretty much pass along what they're fed, with spectacular clarity and imaging.  I have zero urge to move on from these.  The only speakers I’ve heard that I’ve liked as well were Charlie Hanson’s Avalons and a pair of Magico S5 MkIIs, both driven by much higher end amplifiers. 


    • Denon DCM-440
    25+ year old CD player with 5-disc carousel and remote.
    • Modified SMSL C100 DAC

    A Topping E30 was added to my CD player's digital output in 2021.  Wasn't sure what to expect, but it made an audible improvement.  

    Edit October 5, 2024:  My E30 failed after 3 years (I suspect due to a wall wart failure), and was replaced by an SMSL C100 that's modified with a MUSES02 opamp (thanks to my good audio buddy "oranda"), and has a DIY linear regulated power supply... a very notable upgrade!

    • Sansui SR-1050E
    Found this beautiful vintage piece in mint condition locally and was happy to give it a new home. It came with the original Sansui cartridge, but have added an SAE 1000E LOMC cart to it. This has recently been installed as my main TT, and I swap out my Nagaoka and SAE carts on it.

    This TT was put into the main system in late 2024, along with my FrankenNag MP150/500 or the SAE 1000LT.
    • Hagerman Bugle 3

    The Hagerman Bugle 3 phono stage got added recently, mainly because I was having some issues with  the phono section of my vintage Lazarus tube preamp.  It's a nice sounding unit for the money, and can be pretty easily modified, which appeals to my urge to experiment.  I've upgrade the power supply significantly, along with the op amps, and some key resistors and capacitors in the signal path.  It's sounds extremely good these days, and is a welcome addition.

    • Audio Technica LP-120XUSB

    This was a gift from my kids a while back.  I sold my AR-ES1 with a Premier MMT arm and Grado Signature 8 many years ago, which I’ve regretted ever since.  This is the newer version of the LP120"X" that offers some fixes and sound improvements over the former LP120.  I upgraded the stylus to the nude Shibata, upgraded the RCA cables, added a cork mat, damped the underside of the platter with Flexseal, lined the plinth with modeling clay, added O-rings to the tonearm, and weighted grip tape to the counterweight to move it closer to the pivot point.  I also added a zebra wood frame, sorbothane feet, a Brute record weight, and have since upgrade the VM95SH shibata to a Nagaoka MP150 with the MP500 nude line contact profile and boron cantilever....what a fantastic cartridge!  I'm duly impressed with the sound I'm getting from this humble TT, and it’s performance has been enhanced by the addition of a modified Hagerman Bugle 3 to my vinyl playback.

    • Garrard Type A70 Mk II
    This was a 60's era turntable owned by my uncle.  It worked when I got it, but needed more work than I could give it to restore it's original functions, so I stripped away the automation, added a Marantz tonearm with an updated nude elliptical stylus on a Pickering cart, and a custom plinth to make a respectable sounding fully manual table.  I offered this to my son as part of grad school graduation gift.
    • Thorens TD-124 MkI / Ortofon ESL S1000 Gyro Balance Tonearm
    This belonged to my cousin's grandfather.  She mentioned having an old TT in the basement, and offered it if I was interested.  My eyes bugged out of my head, and I stammered a lot when I saw it...I was fully expecting something along the lines of an old plastic BSR, etc.  Wow. A precision beast of an overbuilt machine if I ever witnessed one.  Made in 1958, in excellent condition, not working, but fully intact.  I cleaned it up, did some research and maintenance, and it's alive and well again.  It's back in the hands of my cousin now, and being used regularly.

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