[erikzen]

Introduction

This year has already been monumental for me. It seems that my previous preference for hyper-detailed cans and analytical amps is on the wane. I recently had the opportunity to have an extended audition of the new Triad Audio Valvecode prototype amp for the past month and it has changed my mind about a couple of things. One is that although I like to hear lots of detail in my music, it should not be at the expense of musicality. Some of the hyper-detail I was enjoying, especially through a set of headphones like the Sony MDR-SA5000, kept me from being fully immersed in the music. I have also lost my fear of tubes and now have a better understanding of how tube amplification can make the music sound better. As is often the case with these demos, this has opened my eyes to new things and tempted me to upgrade or expand my equipment. So manufacturers, take note: demos are good for business. So keep ‘em coming guys!

Background

I have never been a “tube guy” when it comes to headphone amps. I was always concerned about heat, space, warm up time and understanding and dealing with tubes. It always seemed like more trouble than it was worth, especially since I have always gravitated more towards the cleaner, drier, analytical sound of solid state amps and like the idea of plug and play. Still, tubes held a sort of mystical allure for me. I do like the idea of tinkering with audio equipment even if I’m not the most knowledgeable guy out there when it comes to electronics.

When Triad Audio contacted my about sending the Valvecode to the NY meet on December 13, of course I couldn’t refuse, but deep down I wondered if I would even spend any time with it at home outside of the meet. Where would I put this thing? Would I burn my house down or worse yet, would I damage the amp and be responsible for destroying a one of a kind piece of headphone electronics, designed by one of the most respected audio designers around? Oh the shame, the shame.

The Valvecode and me at the NY Meet, December 13

However, I had no choice once the amp arrived a few days before the meet to make sure I could get it working. So I made some room in my listening area and set this beast up. And it truly is a beast, too. This thing must weigh 40 lbs. if it weighs an ounce. It accepts two input tubes, two output tubes and is tube rectified for a total of 5 tubes running the amp. The package included a variety of tubes, but more on that later.

Design Notes*

The Valvecode Prototype from Triad Audio

The Valvecode, according to its designer Philip P. LaRocco (ppl), is the world’s first all cascoded single ended triode amplifier. It utilizes triodes exclusively to avoid the nonlinearities of pentodes and remain true to the heritage of the single ended triode amplifier. It is implemented with cascode circuit design for low distortion and extended high frequency reproduction and to improve the performance and musicality of tube amplification.

The Valvecode employs an overbuilt power supply starting with a massive 240 watt power transformer rectified by a high current tube rectifier. It utilizes a fraction of its rated output for long life and low heat. The output transformer has a 100 watt core, laminated with high grade Z11 steel. It has a perfectly layered coil wound on a low loss nylon bobbin. The amp uses the Swiss made DACT CT2 stepped attenuator. It has only one Auricap coupling capacitor in the signal path. It is also fitted with a 6 position rotary impedance selector allowing the use of any headphone from 16 to 600 ohms and has two headphone jacks, one that utilizes the impedance selector, with the other one bypassing it.

The Valvecode is designed to operate with dual triode vacuum tubes with an 8 pin octal base such as tube types 6SN7 and 6BL7 or equivalent. For the output tubes the preferred tubes are the 6BL7GTA and the 6BL7GT and will also accept the 6BX7GTA and 6BX7GT types.

For input the recommended tube types are the 6SL7GT and 6SN7GT or GTA. The 6SL7 ahs more gain and the 6SN7 should provide greater dynamics. The 6BL7GTA also works and results in lower gain than either of the other two tubes but provides the highest dynamics.

The specified rectifier tube is the 5U4GB. The European GZ34 can be substituted with good results.

Initial Impressions

When the amp arrived I had four full size headphones on hand, Grado HF-1, Ultrasone Proline 750, Sony MDR-SA5000 and a pair of Denon AH-D5000 on loan from Lawton Audio with the “markl Mods” and rewired with Jena Labs cable. First up was the SA5000. This is technically my “best” headphone. It has the highest retail price of any of my cans and is recabled with a very well regarded Moon Audio Black Dragon cable (not including the Denos, which are not mine but are more expensive).

The SA5000 is well known as a very fast, clear and detailed headphone. As such, it is also considered to be somewhat fatiguing and can often sound bass shy. Plugging them into the Valvecode was a completely unexpected experience. They no longer sounded cold or analytical but extremely well balanced. Add this to the excellent speed, clarity, imaging and soundstage and the SA-5000 comes close to being my perfect headphone. And if the SA5000 isn’t my perfect headphone, the Valvecode certainly seems like the perfect amp for the cans.

The HF-1 were a nice surprise with the Valvecode. I am the original owner of these very limited edition headphones and I’ve held onto these more for their collectable value than for their sonic signature. Honestly, I have rarely listened to them and if you believe in burn in, they probably haven’t even been broken in yet. Plugging them into the Valvecode however was a completely different experience. The sound was very balanced, full and so much smoother than with any other amp I’ve tried them on. I have a set of Headphile C-pads for these and I thought that the Valvecode added the positive aspects of the C-pads without the negatives. With the C-pads the bass gets deeper and the sound is less fatiguing but it also sounds a bit mushy, losing the detail and excitement that makes the Grados so unique. With the Valvecode, bass was deep and tight, not at all flabby. Details were preserved but the “Grato” sound was completely eliminated. The soundstage was compressed, a signature of these headphones, but instrument separation was greatly improved.

Perhaps the only real disappointment I had with the Valvecode was with the Proline 750s. The Prolines have excellent soundstage capabilities. The Valvecode actually took them to a whole new level in that regard. The sound seemed to expand and encircle my head creating a fairly large stereo image. However, my disappointment came with the sound of the midrange. I’m not sure why but the sound was scooped out, as if the midrange had been cut. There just didn’t seem to be any synergy between the Valvecode and the Proline 750s.

Listening to the Denons took some time to get used to. At first, my impression was that there was too much bass. It was very deep but seemed to overpower the rest of the music. I’ve read some impressions of the Denons that state they need to be powered by solid state amplifiers to sound their best and I can agree to a certain extent, although with some tube rolling I was able to get them to sound very musical, while taming some of the bass. However, tipped the sound may have been towards the low end, the midrange on the Denons was breathtaking. I especially liked the sound of electric guitar, saxophone and vocals. On music that does not have electric bass the midrange is really allowed to bloom and sound so, well, musical.

Tube Rolling

Since the Valvecode accepts the 6SN7 there should be no limit to the amount of tube rolling that can be done. For many tube amp enthusiasts out there, this should be a tube roller’s dream.


Included with the amp were a few sets of alternate tubes: 2 6EM7; 2 RCA 6BL7GTA; 4 GE 6BL7GTA, 2 Black Plate, 2 Gray Plate; 2 Russian 6SN7GT; and the 5U4GB rectifier tube. When I first tried out the amp I got the recommended tube compliment wrong and used the 6BL7GTA in the input and the 6EM7. While this did not produce the most detail and the cleanest reproduction it actually made the SA5000 sound really nice. It was a bit slow and syrupy but I’ve come to the conclusion that this is just what the super fast and highly detailed SA5000 need to sound their best. I had never heard this headphone sound so good. However, plugging the Denons in with this tube combination sounded bloated. It was just too much bass to be enjoyable.

The clearest, airiest sound was realized by using the 6EM7 in the input, the RCA black plated 6BL7GTA in the output section. This gave the Denons new life and gave them a very musical feel with awesome soundstage. The sound of the electric guitar was some of the best I have ever heard outside of standing next to a well warmed up Mesa Boogie Road King. The Sonys also opened up more in this configuration but I could start to hear some of the sharpness to the highs that it sometimes displays. This was also the best tube configuration for the Grados. Where the Sonys still had some edginess to them, the Grados were detailed but smooth. The only drawback to the Grados however is that you really lost any semblance of soundstage as it sounded much more upfront. Not necessarily a bad thing but it did not allow the amp to show off what it does best for me: provide a lush yet detailed stereo image that expands well beyond your head.

I also tried the Russian 6SN7GT in the output stage and that was actually a good match for the Sonys. They lost some of their edge but still had the detail and space that makes them such a great headphone. They remained transparent without being hyper-detailed, which can sound unrealistic. However, the amp seemed to exhibit more hum with these tubes although it did not interfere with the enjoyment of the music.

Lasting Impressions

I’ll start with the negative side and I assume most of these issues have to do with the fact that this is a prototype and constructive criticism will be used to make the production model that much better. First, there was a low level hum that could be heard when no music was playing. This could be negated for the most part by switching the impedance selector and changing out the tubes. I found the 6EM7 in the input and black plated 6BL7GTA tubes in the output to be the quietest configuration. Bear in mind that all of my headphones are relatively low impedance (Grado – 32 ohms; Sony – 70 ohms; Ultrasone – 40 ohms; Denon – 25 ohms) so if I don’t know what it would sound like if you tried a pair of Sennheiser 650s or the like.

It also took a bit of trial and error to understand how to use the ohm selector switch and to understand the difference between the two headphone jacks. This was easily remedied by a few emails back and forth with Phil Larocco and I assume that when the amp goes into production there will be ample documentation.

This is a big piece of equipment. The thing weighs a ton and has a large footprint. This is necessary due to the high quality parts, but the amp is not for everyone. This is certainly not a desktop amp so start clearing out a space in your audio rack now.

Trying to make room for "The Beast".

On the positive side, this amp positively sings. There wasn’t a recording I threw at it that didn’t sound wonderful and even though I complain about the scooped out mids on the Prolines, there were times when I felt they sounded their best also. Dynamics on everything from classical to hard rock were outstanding.

There was a very definite openness to the presentation. On a headphone like the SA5000 the soundstage was absolutely huge, the best I’ve heard. Even on the Grados, which normally have a compressed soundstage, it was expanded to beyond my eyeballs, which is usually my experience with that headphone.

While treble detail and bass “oomph” was certainly there in spades, where the amp really shined was in the midrange. Guitars, vocals, alto sax, all sounded so tangible. This to me is the essence of a musical amp, since so much of the melody of music falls into the midrange.

The true indication of how much I enjoyed the amp was the emptiness I feel now that it’s gone. Music was such an effortless pleasure to listen to with it and my enjoyment of headphones has been reinvigorated.

Please do take what a say with a grain of salt. As I stated in the beginning, I am not a “tube guy”. This is my first extended audition of any tube amp, let alone one of this caliber. It is so hard to express intangible things like the enjoyment of music without resorting to some hyperbole. However, I do consider myself a life long music lover and as such think that in some way qualifies me to comment on this very fine piece of equipment. I do not know the exact details of when this amp will become generally available or what the price will be, but if you are an aficionado of tube amplification or just a music lover like me, you need to check out the Valvecode.

In a Nutshell

Pros

1. New tube design by well respected audio engineer, Phil Larocco
2. Great dynamics
3. Involving Midrange
4. Lush smoothness that does not sacrifice detail
5. Deep and wide soundstage with excellent stereo imaging
6. Many tube rolling options

Cons

1. Low level background hum with some tube/headphone configurations
2. Large size for the real estate challenged
3. "Valvecode for Dummies" manual needed

[size=xx-small]Endnotes

*Amp Design

The specifications on the build of the amp come from the designer, Philip P. Larocco. If something seems incorrect it is probably my fault. Although questions about the build of the amp would be greatly appreciated in this thread, your questions may be better answered by either Phil or Brad Taylor (remitrom on HeadFi). Ideally, they will answer any questions you have here so we have one place to discuss this amp. Over the past month these guys have shown themselves to be extremely knowledgeable, friendly and customer oriented, so I’m sure they would also welcome your private messages.

Source Equipment

Transport - SACDMod DVP-NS755V with stereo modifications
SACDmods.com--Upgrades for the Sony DVP-NS755V DVD/SACD Player

Ack dAck 2.0 with ultra resolution Teflon coupling capacitors
Ack! Industries

Music

While I listened to a variety of music with the Valvecode some the following is a selection of some of the albums that stood out when auditioning:

Chesky NARM Sampler 1991 – Various Artists
Of particular note are the tracks “My Blue Heaven” by John Pizzarelli and “Born in Chicago” by Natasha

Maria Rita – Maria Rita

Raising Sand – Robert Plant and Alison Krause

Tchaikovsy Violin Concerto in D major – Itzhak Perlman soloist

American Song – Andy Bey[/size]

 

[fkclo]

Awesome impressions!

I have also wondered how the ValveCode sounds and thanks so much for the impressions now I have some idea.

This is definitely one of the "die-for" amps. I do agree that if the foot print can be modified so that it is less deep it will be easier to find a place for it. Alternative, would a two box design serve the purpose even better ?

F. Lo

 

[Uncle Erik]

Thanks for the great review and that amp is truly interesting. Any chance it'll make its way west this May? I would love to give it a listen at CanJam '09.

Erikzen, any chance you're going to make the move to tubes? I've had much the same impression of the SA5000 on other tube amps - I have a hard time listening to them on solid state now.

 

[erikzen]

Since Triad is on the west coast I assume it will eventually make it back out there. I have no idea if they are planning to attend CanJam but I think it would be a good idea. It assume it would get their products some more exposure.

I am definitely looking at picking up a tube amp. I've been reading up on some of the entry level offerings. I've been considering the LD MKIII and Lunchbox II. I'm not sure about the Lunchbox with low ohm cans though. I've read conflicting information on that. I will eventually email Eddie Current if I decide I'd really like to buy it. The SA5000 definitely needs tubes, although the Valvecode is going to be out of my league, at least in the short term (like until I pay off my mortgage!).

 

[Rob N]

6FM7 isn't that a double dissimilar triode with a compactron base?

 

[erikzen]

Quote:

Originally Posted by Rob N /img/forum/go_quote.gif 6FM7 isn't that a double dissimilar triode with a compactron base?

Looking up the codes you are right, it is. 6FM7 was marked on the box but now that I think of it on the tube it was marked 6EM7, which should be identical triode cells and an octal base. I will make the correction.

 

[Skylab]

Erikzen, nice review! Well done and a good read. Thank you!

The ValveCode prototype is on its way to me for review, and I look forward to hearing it.

 

[Rob N]

Quote:

Originally Posted by erikzen /img/forum/go_quote.gif Looking up the codes you are right, it is. 6FM7 was marked on the box but now that I think of it on the tube it was marked 6EM7, which should be identical triode cells and an octal base. I will make the correction.

6EM7 still has dissimilar sections,one high mu one low mu.How does it work in this amp?

 

[erikzen]

According to the designer a dissimilar triode can be used but it is not optimal. I used the 6EM7 in both the input and output as it was recommended to me by someone who had auditioned the amp prior to me. Not having a lot of experiene with tubes and really only having the amp for a month, to me it sounded excellent. I found by putting it in the output, it may have lacked some punch but was very lush sounding. Putting it in the output produced a more detailed sound.

I would probably have to say though that having 6BL7 tubes in both input and output gave the best overall sound.

 

[jpelg]

Nice review, Erik. Well done!

Seems like you've gone "whole hog" by immersing yourself into some serious valve knowledge. Glad you are enjoying the journey.

 

[ghostmusic]

Erikzen, did you try both the OTL configuration and the traditional transformer output? If so, I was wondering if you can give us a feedback on the difference between two modes... I heard that you can choose between the two?

 

[erikzen]

Quote:

Originally Posted by ghostmusic /img/forum/go_quote.gif Erikzen, did you try both the OTL configuration and the traditional transformer output? If so, I was wondering if you can give us a feedback on the difference between two modes... I heard that you can choose between the two?

Yes it's true. There are two headphone jacks and one is from the tranformer the other directly from the tubes. I would have to say the differences were subtle and I would need more experience with both this and other amplifiers to make a definitive comparison between the two. However, I will say that I ended up listening through the OTL jack more often. I can't really say why but it just was more enjoyable.

Quote:

Originally Posted by jpelg Nice review, Erik. Well done! Seems like you've gone "whole hog" by immersing yourself into some serious valve knowledge. Glad you are enjoying the journey.

Thanks Jimmy! It's been fun so far but I feel like I still have so much to learn. Many thanks to Triad for enhancing my education.

Quote:

Originally Posted by skylab Erikzen, nice review! Well done and a good read. Thank you! The ValveCode prototype is on its way to me for review, and I look forward to hearing it.

Glad you enjoyed it. Hopefully it does something to add to the knowledge base.

You should be receiving the amp today if you haven't already.

Quote:

Originally Posted by Uncle Erik Erikzen, any chance you're going to make the move to tubes? I've had much the same impression of the SA5000 on other tube amps - I have a hard time listening to them on solid state now.

I couldn't resist. Yesterday I bought a Little Dot MKIII. It's a toy compared to the Valvecode but it's something to learn from and goof around with until I can save up enough for a Valvecode.

 

[vcoheda]

great review.

it certainly sounded good.

 

[jpelg]

Quote:

Originally Posted by erikzen It is also fitted with a 6 position rotary impedance selector allowing the use of any headphone from 16 to 600 ohms and has two headphone jacks, one that utilizes the impedance selector, with the other one bypassing it.

Perhaps that's why we didn't hear significant changes when we played with that switch at the meet?

Can you elaborate how this is implemented in the circuit & should be used by the listener?

 

[ppl]

Thank you Eric for your thoughtfully honest review of my latest Design. I can completely relate to your fear of Tubes. I like yourself come from a Solid state background and also was completely put-off by high voltages and the horror stories I hear often about this or that Tube Amp blowing up for no apparent reason. I even have to witness such an event live and in person at one of the few meets I attended. This incident also involved electrostatic headphones. This totally convinced me I wanted nothing to do with tubes or high voltage, even thought the mega detail of electrostatic cans can be captivating! one must ask themselves is this really worth your life???.

There must be a tube Amp Virus permeating the very air we breathe because since about the 1980’s tubes and vinyl becoming used more and more, however I simply attributed this to nostalgic reminiscing of the good old days, like Classic cars and Watches. While I went about my marry way in the sand I kept thought of thermionic butterflies displaying their sublime charm. Earlier this year for no apparent reason, I just had to have a tube amp. However, I did not want just any tube amp and I simply did not want a tube amp for the sake of having a tube Amp ether. (Yes, I also have and Enjoy several separate Systems) However, I wanted to revisit the technology with a clean slate and first off define just what I did not find attractive about tubes the most important deterrent for me we already covered however there remained serious technical issues that always seemed to plague tube amps. I made a list of these and set about what I believe were logical solutions without resorting to the use of solid-state devices

Since I have a phobia of transistors self destructing in the presence of heat and high voltage. Another scary item about tube amps is Biasing and customers tube rolling, We have all read about tubes arching inside, Glowing Red parts of the tube that are not intended normally to have a glow of their own like the Plate. To solve this issue one must simply look at how our grandfathers dealt with this situation. After all, even in the tube era most people were cautious around electricity so the tube amps for mass-market consumption had to be plug_and_play. When it became time to replace tubes customers demanded the ability to go to their local drug store or supper market where one would find one of THESE then plug in the tubes removed from the malfunctioning gear note the defective tube and simply insert the replacement tube in the socket where the defective tube was previously. Plug and Play simple, No bias to adjust no balancing to set. The bad side of that was this only was only available on Inexpensive appliance equipment for cost savings by not having to include bias adjustment components. The disadvantage to this is the tubes were often Biased on the low conservative side so performance of this type of equipment is seriously hampered from the onset from this aspect alone. The true high Fidelity and professional Amplifiers can include tube adjustment facilities in the Amplifier without additional cost. These procedures’ still required skill and dedication if it is to be done correctly, so Audiophiles routinely delegated this to the local TV & RADIO service facility or Dealer’s service shop.

I did not want people to go through a long and potentially dangerous adjustment procedure every time they changed tubes. I used cathode biasing with resistors augmented with resistive local feedback networks to provide automatic bias adjustment of the tubes via self-biasing so the output tubes are operated at their ideal dissipation regardless of age or brand. The tubes simply find their own comfort zone and operate there and this zone can change as the tube ages. This way the advantages of adjustable bias to assure the tubes are operating at there intended point with no worries.

This is my 1st tube Amplifier design in over 3 ½ decades so it is still evolving however from the prototype the Production units are smaller and are built upon my Full metal jacket PC Board to hopefully deal with the slight hum of the Point to point build of the prototype. The chassis is more compact footprint of 14” W X 12” D from the prototype’s 15 ½”W X 16”D Unfortunately, it still is heavy. Actually, I could be 14 LBS More as I upgraded the Output transformers to ones with 2.5 the Inductance for more extended Bass with substantially lower distortion. You will notice that the lower Left corner of the Chassis is vacant real estate; I am looking for suggestions of what to put in there? Perhaps a tube Magnetic Phono preamp? The circuit I know tube Amp people want to know what kind of Circuit is utilized, this document should answer those questions.

The 1st run of Amps we will offer no options however limited Options and custom request may be entertained in the future. Since this Amplifier is Expensive as all get up just in parts Brad have to make a minimum number of units to make it worthwhile so this initial Launch will be fixed in this regard however you will have everything needed. Basically you get one set of unbalanced CARDAS RCA Inputs, 2 sets of unbalanced ¼” 3 conductor Headphone sockets, A do all Medical grade power entry module that incorporates Fusing, Power on/off switching.

The OTL connection was used only on the prototype the production unit will have both jacks connected in parallel so that two people with the same type of headphones can listen at once. The OTL connection in the prototype is via a 330uF 450 Volts low Z Electrolytic capacitor connected to the plate of the output Tube along with the power transformer. The Valvecode is going to be produced in the same efficient Electronic assembly facility as LISA III and Headcode so quality will be maintained from unit to unit like LISA III. The standard TRIAD Audio operating procedure will be used on the Valvecode like LISA III, once all stock is sold the buy now button for the Product will be removed so no sales can take Place until stock is replenished. This way customers get there Amps as expected in a quick and timely manner. Since professional electronic Assembly, facilities assemble all TRIAD Audio products Quality will like LISA III be 1st rate with few if any malfunctions while in use and the one or two defects that mistakenly slip by are promptly replaced. The Primary reason for sending the Amp out was to get an idea what if any changes folks would like to see in the production unit. Brad really listens to what his customers say and passes down that info to myself, the machinist as well as service and assembly people. Service as well as modifications are performed by a professionals service shop that specialists in professionals Studio and pro Audio Equipment. TECHRON and Brad work together on customer requests, upgrades, Options and good old fashion Quick competent Service with a smile.