This is an advanced parafeed designed headhone amp. The designer is Doug Savitsky and is built by Tom Beezar of Beezar Audio. This is the most advanced amp that has a lineage developed from the original Torpedoe T1, T2, T3 and now the T4, no longer called a Torpedo…
You can read some very interesting stuff on SBAF where Tom goes into a long history of how Beezar Audio came about, and really interesting stuff in the early days of headphones and all the todays power players!! IMO a must read.
Beezar Audio/ECP Audio History
Marv graciously created a subforum for Beezar so that Dsavitsk (ECP Audio) and I could tell you a bit about ourselves, how we got started, and maybe…
T4 Headphone Amplifier by ECP Audio, exclusively assembled and sold by Beezar Audio
*****NOTE: T4 Total Price is $2000. Pre-Orders accepted with $1000 deposit, non-refundable! A new set of completed amplifiers are estimated to ship by mid-October, 2019. *****
*** Each customer with a deposit will be contacted prior to shipment for the final $1000 payment ($2000 total for the T4) and shipping costs. ***
Just some of the incredible features of the T4: * Custom machined and finished casework with hand-oiled wood sides
- ECP Audio custom-designed Lundahl output transformers
- Audience Auricap XO parafeed capacitors for the finest detail and tone
- New thin-film Vishay/Beyschlag resistors throughout
- Special Vishay low-noise nickel chrome tube plate resistors
- SMD differential circuit with thermal bar, full case dissipation for optimum heat transfer
This is it! The T4 differential hybrid parafeed headphone amplifier, custom assembled by Beezar Audio. Created by ECP Audio’s Dsavitsk, the T4 continues in the tradition of the Torpedo III with its totally unique design in the world of headphone audio. The T4 combines tubes with a fully differential solid-state output, feeding into custom-manufacture Lundahl output transformers for the finest single-ended, zero-feedback output. The result is perhaps the finest tube headphone amplifier available anywhere at this price point.
For those of you familiar with ECP Audio designs, the T4 is a tube-fed DSHA amplifier!
Why a fully differential circuit but single-ended on the output?
Answer: Because circuit/device distortion is fully cancelled out by the solid-state output portion of the circuit. At the same time, combining the solid-state output with the tubes results in more power than would be available simply from the tubes. The output transformers assist with this, ensuring that ample current and voltage are available, regardless of the impedance of the load.
As before, ECP Audio designed the T4 headphone amplifier to utilize the ubiquitous 12A*7 audio tube family. Specifically, the T4 is designed for the 12AY7 or 12AT7 tube, but others can be used that meet the general 12AT/U/V/X/Y/Z/7 tube specifications. There are many, many other tube types that will work, too. Refer to the Torpedo III website for a list. All tubes that worked in the Torpedo III should perform excellently in the T4.
The T4 includes a “Z” switch that allows switching between low and high-impedance loads (75 to 300 ohms). This switch may be thrown at any time - even while music is playing and headphones are plugged in. Note also that with a true, output-transformer-coupled amp, there is no need for any kind of power-on or power-off protection.
The good news is Tom is sending me a T4 on loan for a few days to experience this latest iteration of a high end parafeed amplifier.
I will share my findings with the community ASAP.
Alex
Ok I finally got thru several days of being sick and under the weather but we finally got time to listen with the T4 in great detail!
Tom Blanchard of Beezar Audio recently contacted me on Head-fi about some comments about his T3 torpedo para-feed headphone amp I made in a recent review. I got a note from him that explained how the issue had been corrected. In the conversation Tom asked me if I was interested in taking a listen to his new ECP Audio T4 para-feed headphone amplifier, this was back in December and here we are in Feb of 2020 and I just received the second prototype T4 which he uses as a loaner. Its pretty much the same amp electrically and has a few cosmetic changes, like smaller vacuum tube openings and logo. Sonically its the same as the production runs Tom has built and sold.
Until I met Jim Hagerman and his Tuba para-feed amp several months ago I really had no clue that there was another para-feed headphone amp out there. Tom has been involved with the Torpedo series headphone amps for quite sometime and it has gone through several “long” shaped iterations.(hence torpedo).
This amp, the T4 is the first amp that the shape has morphed into a more desktop rectangular shape with some nice looking walnut wooden sides. Toms opinion is the T4 is different than the T3, by quite a bit. “With the T3 he seemed to find a magical tube in the 12AZ7, even though it ran very hot in that amp (higher heater current). The T4 seems to prefer a regular 12AT7 tube best, with the best quality 12AT7 tube performing as advertised from audiophile tube sources. In that vain, the new JJ 12AT7 tubes are superior to the Electro Harmonix 12AT7 tubes,even though I’ve always thought Electo Harmonix tube construction was superior. (You will find JJ tubes varying by 1/4" or more in length!).” (this is from Tom directly).
My experience is with the T4 only, and not a comparison with the 3F which is a solid state amp designed for the Focal Clears to handle its undamped drivers. The T4 is a high voltage, low current amp, the 3F is a low voltage high current amp. And the T4 has a tubes in it 
As stated in other comments, the T4 was designed to work with a wider range of headphones and impedance’s and utilizes some very special low DC resistance output transformers made by Lundahl. There is a Hi/Lo Z switch on the right front side.
From the Owners manual description:
" The T4 differential hybrid para-feed headphone amplifier amplifier , custom assembled by Beezar Audio was created by ECP Audio. The T4 continues in the tradition of its predecessor, the ECP Audio/Beezar Torpedo III. Its circuit and configuration are totally unique in the word of headphone audio. The T4 combines tubes with a fully differential solid-state-output feeding into custom-manufactured Lundahl output transformers for the finest in single-ended, zero feedback output from a headphone amplifier. The result is perhaps the finest tube amplifier available anywhere at this price point.
The tubes are configured in a long-tail pair that results in a fully differential output. From there a fully differential solid state buffer is used, terminating in output transformers configured into a para-feed arrangement, where the differential signal is combined back into a single ended connection at the headphone jack… Because of the fully differential circuit, common mode distortions is fully canceled out. At the same time, the solid state buffer output after the tubes results in more power than would be available from the tubes themselves. The output transformers assist with this, ensuring that ample current and voltage are available, regardless of the impedance of the load.
ECP audio designed this amp to utilize the ubiquitous 12A*7 audio tube family. Specifically designed for the 12AY7 or 12AT7, but others can be used that meet the general 12A(T,U,V,X,Y, Z)7 tube specifications. The Z switch is a 75or 300 ohm choice. Toroid transformer, ALPS Blue Velvet potentiometer, Special Visahy low-noise nickel chrome tube plate resistors, new thin film Vishay/Beyschlag resistors throughout. Finally a new advanced thermal bar heat rejection through casework.”
SPECS:
The overall look of the T4 is simple elegance, a large volume knob makes for easy articulation. Its smooth and stays put at all positions. I might state here that the amp is dead silent at any volume output, or impedance switch setting. There are no turn on or off thumps to startle you. The only other port on the front is the large 4pin XLR port. My focal Clears plugged into this with the balanced cable and works fine. If you have SE cans only you will need a special XLR to TRS adapter cable. Tom included one in the box and I used it to connect my HD600’s and it worked just great. I think the adapter is a $50 option.
I have built many, many DIY amp, Amateur Radio gear and torn in to lots of retail products to look, see and modify stuff, and I can easily tell if something is well thought out, built well, etc…and the T4 is very well thought out and put together nicely. Its a simple laid out amp with high quality components, great soldering and tube sockets that are very well connected to the PCB. Even with this prototype inserting and removing tubes required a good amount of physical effort and you can be assured that your tubes have a great solid connection. In the T4 I received there are 2 yellow Auriacps XO, instead of the white caps in the pictures above…Tom tells me the Auricaps were a solid design choice for them and the photos will be updated to reflect the new Auricaps.
Tube changing requires removing the top lid via several small machine screws and using a small plastic tool to gently pry up the top and remove. Once inside tubes are easily accessible. Insert tubes, replace and screw top back and your good to go. Simple.
On the back side there is a power on/off/fuse unit to attach the power cord and on the opposite side a single set of RCA phono plugs for your source connection. I used simple Y-connectors off the back of my dac to run to two amps for fast comparisons.
Tom sent me two sets of 12AT7’s to play with, one set of CV4024 Mullards and a set of JJ 12AT7’s. More on that later.
First impressions are usually lasting ones. My first impression with the T4 was indeed a very, very good and lasting one. What impresses me most is of course how does it improve or make my listening experience better and secondly how well is it built. The pedigree of the T4 over the years speaks for itself and with the changes to lowering the DC resistance with those really special Lundahl transformers speaks volumes in the design of the amp and the the results are very apparent.
NOTE: All music was sourced via a new Schiit Bifrost2 True Multibit dac, via USB to a HP 27" AIO using the Schiit Unison Interface. Jriver MC 24 setup up for bitperfect playback was used, no weird stuff or plugins or eq’ing.
This is an amp that tells me “STOP thinking about specifications, power output, and just listen to the music “stupid””. From the first moment I turned it on and hit play, not even with my demo stuff, just some random stuff vial Jriver MC24 my jaw dropped and I was instantly mesmerized. OMG for the next two hours…not jumping around trying to find that tune that makes things sound good, it all sounded good…the tubes in the sockets for this first audition were the CV4024’s.
I started out the first night with just the Focal Clears, the second day I moved to the Senn 600’s. Low Z for the Clears, Hi Z for the Senns. I have never had an amp that paired with the Clears tonality characteristics as well as the T4. Matter of fact this has to be one of THE best pairings for the Clears period! Over and out!..
Day 3 I powered up the Bottlehead Mainline for a comparison, starting with the HD600’s level setting and making sure all the switches on the Mainline were set to HIGH impedance and UNBAL outputs, we started listening to Cowboy Junkies. Trinity Revisited, Dreaming My Dreams. The opening bass and male voice was delicious on the T4 and with a quick switch to the Mainline, the presentation was very similar! Both setups were delivering sound that was very close in comparison. The bass tightness on the T4 was slightly tighter or it seems to be at times but we are splitting hairs here.
The ambiance and background minutiae was present in about the same detail. But the T4 just eeks out the Mainline in clarity.
Second song was Eva Cassidy, Time After Time, I wish I was a Single Girl…her voice and strong guitar strumming here are in your face wonderful. The holographic depth the the sound-stage, hearing those studio reverberations are clearly heard. Tonality of the guitar strings are very well reproduced.
Third song was an old Eric Clapton, The Cream of Clapton, Badge, and this is a mediocre recording and it sounded equally mediocre on both amps! But popping on Eric Claptons 24 Nights and the Bad Love rendition…totally different story! Excellent recording and the T4 shine very, very well here! A live rock and roll session with Clapton at his best!!!
Fourth song was Michael Buble’s, Michael Buble, Fever! Wow this one the winner is decidedly the T4 here, but not by much. The difference in this recording compared to the others is this is a typical loud, brassy, fast sharp transients you hear from a Las Vegas nightclub band…BAM! in your face…The presentation with the T4 was just a little different in that it was more holographic and the tonality was just more to my liking…again either one is great, but we all have opinions. I would have to say the T4 is more accurate in being able to present all what in this recording, with no faults attributed to the amp, as the Mainline adds some smoothness to the overall sound…depending on the source materiel, time of day, your mood etc…this could change.
Alison Krauss, A Hundred Miles or More, A Collection, Jacobs Dream…Alisons beautiful voice and guitar strumming here are very, very well done, clear, and her high voice reverberate throughout the room…It was again pretty much a tie for both amps. the difference again with good recordings seems to be a slightly overall clarity and bass control of the T4 over the Mainline…
Switching over to the Focal Clears, Mainline set for Low impedance, and balanced output, quick level match…and up comes Rhythm Devils, the Apocalypse Now Sessions and Cave…what a weird strange recording, but it has lots of minutiae and minuscule sounds that actually make for interesting testing of stuff…Both amps did well.
Next up was an explosive Mino Cinelu, Mino Cinelu, Will O’the Wisp…WAHM!! the Both amps did very well…bass drum lines and bright distinct cymbal crashes with huge drum slams will surprise and shock you if your too loud…plus throw in a male voice…very busy recording excellent demo track.
Listening to Dave Brubeck – Time Out Classic…with the Clears…Simply the best I have ever heard…cleanly defined bass drum whacks that are so real…explosive…
Trying our a set of Beyerdynamic T90’s was a nice surprise on how well they worked in Hi Z mode with the T4. The ususal treble sparkle seemed to be tamed down just the right amount. The T90s are 250 ohms and they have enough power to be driven exceedingly well…From Special EFX , Slice of Life to Luiz Bonfa’s Non-Stop to Brazil. Keiko Matsui, Dragon Wings a holistic reproduction! Clean, crisp and articulate.
The Clears on the T4 have never sounded so tonally accurate and crisp…not over done just soo sooo right IMO. Again both amps are great, musically its hard to choose one over the other…but the T4 again edges out the Mainline with its slightly tighter overall control on the low end and overall clarity…like we are talking in the high 95% + area of getting to a perfect no faults, which doesnt exist in my book…
Lastly there is no complete test with out some LeaAnn Rimes country and western stuff!! LOL…Not my favorite genre but some of her recordings are so well done you can cut thru glass with them! LeAnn Rimes Unchained Melody" The Early Years…Sure Thing…This is CW Jukebox music and your gear if its any good should be able to handle this with aplomb! Both amps do well again, but this time the T4 just takes is away in handling everything, Fast transients, loud in your face piercing vocals with no sibilance. Some female voices can really grate on your ears, like Adele for me. but Rimes is like listening to a human glass cutter, amazing. the T4 handles this so well.
HD600’s attached with the XLR to TRS adapter cable:
This wasn’t meant to be a T4 vs Mainline shootout, but I wanted to see how two high end tube amps would fare against each other…and both do very well. Which one to pick? Well if you really want the best and can afford $2000 the T4 is the answer. If you like 12AT7 tubes…you can play to your hearts content, and no internally bias adjustments are required and you dont have to spend mega bucks on tubes, the CV 4024 are around $60 a pair…and worked so very well… With the Mainline the 6C45pi’s are pretty much it, not many other affordable options out there. The T4 only has the one Neutrik 4-pin XLR headphone jack , compatible with 4-pin XLR balanced headphone connections,so if your using balanced cables your set to go, There is no 1/4" phone plug, so for your SE cans you need to purchase an adapter to convert from 1/4" stereo to XLR. The one provided to me by Tom is an excellent TRS to ¼ cable, high quality and will stand the test of time.
So in closing, if you have a set of Focal Clears and want one of the best amps for them the 3F is out there if you can catch one, but its designed again for these cans…while the T4 will play the Clears so much nicer than many other amps AND if you want to use your HD800’s and other high impedance headphones, well the T4 can do that as well!! The T4 is a no-brainer choice IMO.
I want to thank Tom Blanchard for allowing me to listen to this marvelous amp, its a real winner and whoever winds up with one will have a piece of gear that will provide thousands of hours of enjoyment. I really hate to send this one back! Its really world class!
Maybe someday!!
Alex
