Amperex 7308 dual triode tubes come in three basic flavors:  white, orange and green.  These colors are an indication of when the tubes were made with white label tubes produced between 1959 to 1967 and the orange and green ones made from 1967 to 1975.  I’m not sure what, if anything distinguishes the orange and green labeled tubes.  It may be just the color of the ink used.  The Amperex 7308 was made in the Hicksville, NY and Heerlen, Holland manufacturing plants.

Some tubes of this type bear the “PQ” shield on their labels while others have the Amperex globe logo.  They all bear the Amperex four-seam, ridged top and have gold pins.  The 7308 was created as an upgraded 6922 with improved resistance to shock, vibration, and was also designed to have lower mcrophonics than the 6922.  It’s rated as having a 10,000 hour life expectancy.

The Amperex JAN 7308’s used in this review are all from the Hicksville plant, were produced in 1968, and have the green globe logo.  They were intended for military use and that’s why they bear the acronym “JAN” (for Joint Army Navy) in their labels.  Two of the tubes in this review were from Vintage Tube Services and bear the distinctive red and green paint on their tips which indicate that they have ultra-low microphonic test scores.  These are microphonic scores appropriate for a line level preamplifier but below a moving magnet or the even more stringent moving coil grades used in phono stages.

Upscale Audio carries the Amperex 7308 for $50 to $80 each, depending upon grade, and VacuumTubes.net has them for $80 a piece.  They may also be found at other online tube sellers and auction sites.

Even though the tubes in this audition were previously used by me, they did take some time to settle in before sounding their best.  Total playing time during the course of the audition was 25 hours.

The dual triode tubes used previously in the Premier 16LS2 were the Amperex USN-CEP 7308 and Telefunken 6DJ8.  Some comparisons to those tubes will be made below.

Listening Impressions:

• The green label 7308’s present the typical grainless quality of Amperex but with a bit more bite than the USN-CEP white label variety.
• Drums are resonant and provide a more solid foundation to the music than was the case with the TFK 6DJ8’s.
• Timbre and decay are excellent with music realistically sustained and then fading into the noise floor.
• Clear midrange that makes understanding dialogue no chore.
• Detail is excellent with instruments easy to pick out of the mix and follow.
• Electronic instruments such as synthesizers are exceptionally well rendered.
• Treble is accurate to the limit of my hearing with sharpness when it’s called for by the program material.  Although instruments such as massed violins are generally smooth, they are never dull sounding.
• Reference level sound staging that projects solid images well into the listening room.
• Music is enjoyable and permits an emotional connection.

Although some are of the opinion that all Amperex 7308’s sound the same, that hasn’t been my experience.  I’ve always felt that the white label version has a slightly more refined sound while the green is more incisive.  I don’t believe that I’ve ever assembled a set of the orange label 7308’s and therefore do not have an opinion of them.

This tube has been a long time favorite of mine both in the c-j Premier 16LS2 and Premier 140, where it’s used as the input tube.  Although the rankings of my favorite 6DJ8/7DJ8/6922/7308 tubes change position depending upon what power tubes they’re being partnered with and quite honestly, my mood, this particular type has always been in my top five or six.  This is due to its ability to play well with just about any output tube I’ve used and in my opinion, none come to mind where the combination was anything other than salutary.

If you’re fortunate enough to be able to purchase these, you will most likely not be disappointed.

The physical description of the 6550EH is basically the same as the KT88EH:  it is a top getter only, three-hole grey plate tube with a chrome-colored collar and black base.  The 6550EH is less expensive than its fraternal twin, the KT88EH.  You can purchase a single tube for $29.95 at Upscale Audio and a matched pair will cost you $49.95 at the Tube Depot.  I’m sure it is also available at many other tube vendors since it is still in current production.

6550EH front view                                                                                  6550EH rear view
             

 
6550EH close-up
 

A Little Background

The New Sensor web site states that the 6550EH dissipates 42 watts in tetrode mode which makes me wonder whether this is really more like a KT88 than a 6550.  (A 6550 output tube is rated at 35 watts dissipation while a KT88 dissipates 42 watts.)  However, they also spell Genalex as “Genelex” in the same ad copy and that makes me wonder, too, how closely I should pay attention to their ad copy.

And speaking of ad copy, every single description I read about this tube, regardless of the web site, states that the 6550EH has “four-pillar construction” even though I count six.  Four of the support rods clearly run from top to bottom.  Maybe the other two are just additional supports for the getter splash screen but they certainly seem to me to be embedded in the plates and then come out the bottom.  I have two words for you:  Sturgeon’s Revelation.

All four tubes under review were manufactured in November, 2001 and, therefore, may bear no relationship to current production.  One of them has the tell-tale greenish cast.  Perhaps that has to do with the leaded glass formulation that New Sensor says is used in their construction.

The tubes continued to change, for the better, during the audition and didn’t fully burn-in until approximately 28 hours total playing time. Because of this relatively long time period, I believe the tubes were unused prior to auditioning them.  The KT88EH, in comparison, took less than half that time (about 12 hours) before they were fully settled-in.

Two comments before I get to my Listening Impressions.  There seems to be a real dichotomy between how I feel they sound when listening to music on CD and LP versus the sound portion of video on a source such as cable or Netflix streaming through my Oppo BDP-95.  I preferred them with purely musical source material and quite honestly, I’m not sure why there was a difference.  When listening to music, I prefer these to the KT88EH but the case is reversed with video sources.

Second, although the 6550EH appear to be physically identical to the KT88EH, except for minor differences in bottle shape, and their claimed dissipation is the same as a KT88 type tube, they do not sound identical.  That having been said, they sound more similar than dissimilar.  I don’t think I’m in “how many dancing angels” territory here, but thought you should know.

Listening Impressions:

• A little bass shy and lacking the articulation heard with very good output tubes in the 6550/KT88 family.  At times, it seemed more thuddy than deep.
• Violins were pleasant but too soft without any bite at those times when they should’ve had it.
• The “clacking” which sounded so realistic with the GEC KT88, is much less realistic this time around. 
• Crowd noises and clapping weren’t as nicely defined as the KT88EH.
• Their strength is in the midrange.  Listening to Sade’s “Love Deluxe,” there were times she sounded like she was in the room and there was a rich, creamy texture to her voice.
• Dynamics and detail were better than the KT88EH but still nothing to write home about.
• Very good sound stage abilities and similar to the KT88EH, there was more to be heard behind the plane of the speakers than typically.
• Images were compact and, for the most part, occupied their own space with only occasional blending of imagery.

The 6550EH doesn’t have the apparent power and smoothness of a GE JAN 6550A or the clarity of a three-hole Tung-Sol 6550 but at 1/5^th the price of the former and 1/10^th of the latter, the comparison is unfair.  However, when viewed from the context of more cost equal offerings from Russia and China, they still do not shine in my opinion.

It isn’t that they do anything especially badly.  The bass could go deeper, the treble could be more open but I could say that about a good deal of the output tubes in this family that I’ve reviewed of late.  But ultimately, they just leave me cold.

Of course, your mileage will most definitely vary.

The Electro-Harmonix KT88EH can be widely purchased from online tube vendors such as Upscale Audio for $34.95 each and the Tube Depot for $59.95 per pair.  The KT88EH is a top getter only, three-hole grey plate tube with a chrome-colored collar and black base.  Two of the tubes in this matched quad have a decidedly greenish cast to the glass bottles.  To my eyes, the KT88EH looks remarkably similar to the Electro-Harmonix 6550EH, differing only in bottle shape.  I would assume, however, that there are electrical differences between the two.  Whether these differences extend to how these two output tubes sound, will remain an open question until the 6550EH review.   

 KT88EH Front view                                                                               KT88EH Rear view
        

KT88EH Close-up                                                                                 6550EH and KT88EH side by side.  Note the greenish cast to the KT88EH
         

The quad of KT88EH in this review, although in my possession for years, had only a little use on them and continued to improve for the first day and a half (approximately 12 hours) of my audition.  My comments are based on how they sounded to me after they were fully broken-in.  Total playing time was about 27 hours.  .

Listening Impressions:

• Lacking in deep bass
• Average (good) treble transients and a bit closed in on the very top of the range (that I can hear).
• Very  good midrange with clear dialogue and vocals; realistic in portraying clapping and crowd noises.
• Macro-dynamics are somewhat reined in and I find myself turning up the volume two or three clicks from its normal position (so about a 1.5 to 2 dB boost in level is needed).
• As I have found to be typical of most output tubes in the KT88 family, soundstage width, depth and height are a borderline 4 out of 5 (where fair = 1, good = 2, very good = 3, 4 = excellent, and 5 = reference level).
• Image specificity is very good with more going on behind the speakers than typically the case.
• In general they are pleasant sounding, although ultimately just competent and somewhat uninvolving.

In the final analysis, I would place these on par with the Shuguang KT 88-98 at the bottom of the output tubes reviewed so far during this phase of auditions.

Sidebar:

A reader’s review in Upscale Audio has the statement that “the KT88EH and Gold Lion are virtually the same tube, with the Gold Lion recieving (sic) more QC/QA and a really spiffy paint job.”  Now, the KT88EH that I have are from October, 2002 and January, 2003 but I’ve also looked at the picture of this tube from Kevin Deal’s web site and his tube is from July, 2006 and the New Sensor Gold Lion KT88 and the KT88EH are most definitely structurally not the same tube. 

The differences I noted, from top to bottom:  The KT88EH has a single top getter ring while the Gold Lion has two top getter rings;  the KT88EH has six support rods while the Gold Lion has four; the KT88EH has a circular getter splash shield while the Gold Lion’s started as a circle but had its two opposite sides squared-off plus it has a large hole in its center that the KT88EH lacks; the KT88EH has no side getters while the Gold Lion has a centrally located side getter on either side.

I think you can tell from this description that while the same parent company, New Sensor, may produce both of these tubes, they are, in fact, quite different in appearance and, in my opinion, are nowhere near in sound. 

The lesson to be learned here is to not take everything you read, including my own ramblings to be the gospel truth.  Remember Sturgeon’s Revelation (usually mistakenly referred to as Sturgeon’s Law):  “ninety percent of everything is crap.” 

I thought that a further discussion of the differences between TFK tubes and TFK-branded tubes manufactured by Siemens might be of interest.

NB:  The tube that was actually made by Siemens was noted as such by the Internet tube seller, so there was no monkey business involved on his part in this transaction.

The first photo shows what appears to be a Telefunken manufactured PCC88/7DJ8 dual triode standing next to the TFK box in which I received it.  As we shall shortly see, this tube was, in fact, manufactured by Siemens.

In the second photo, we have two PCC88/7DJ8 tubes that are both labeled as Telefunken.  The tube on the right is the one actually manufactured by Telefunken while the other was made by Siemens & Halske.  From this photo, it’s really not possible for me to tell one manufacturer from the other.  Although note the construction differences between the two.  Specifically:  the size of the top getter flashing (the one on the right does not extend as far down the top of the tube), the positioning of the getter ring support (the one on the right is bent) and the presence of a getter splash screen on the right-hand tube.

The third photo shows the bottom of the tube.  Note that there isn’t any diamond shape molded into the bottom of the glass between the pins.  What we do see is the number “6” which also happens to be imprinted on the tube’s box.  The lack of the diamond indicates this isn’t actually a TFK tube.  In addition, Siemens typically molds a number into this part of the tube.

In the fourth and final photo, we see the top of the suspect tube.  Note the four seams which are not found on TFK tubes but, as mentioned in Part 1 of the TFK ECC88/6DJ8 review, is an indication that a tube’s been made either by Amperex or Siemens.

Finally, although it can only be seen partially on the left bottom-side of the first photograph, the following is imprinted on the tube:

DJ8
≠0K

The “DJ” signifies that this is a PCC88/7DJ8 type tube and the number “8” indicates it’s from the eighth construction iteration of this tube type.  The “≠” indicates it was made in the Munich plant of Siemens & Halske, the “0” indicates it was made in 1970 (an educated guess as to the decade, I doubt if it were 1960) and the “K” which is the 11^th letter of the alphabet tells us it was made in November.  Typically, a number would follow the letter "K" indicating the week of the month in which it was made, but it was not present on this particular tube.   

The next installments will most likely focus on two output tubes from Electro-Harmonix:  the KT88EH and the 6550EH.

The TFK ECC88/6DJ8 tubes used for this review were well broken-in but, as is typical, changed character a little over the course of their audition.  During the second day they were in the Premier 16LS2, I hooked-up three sets of Shunyata Venom3 power cords to the Oppo BDP-95, the c-j 16LS2 and the Olive O3HD music server.  The power cords had just arrived from being treated on an audiodharma Cable Cooker (as always, thank you, John) and the difference was both immediately apparent and taken into account.

I think it’s important for the reader to have as much background information as possible in order to properly evaluate what’s being described.  Many of the qualities noted are in direct comparison to the Amperex white label 7308 tubes that were in the 16LS2 just before switching to the TFK’s.

Listening Impressions:

• The TFK’s present a clear representation of the sound with a touch of sweetness but to a lesser degree than the Amperex 7308’s.
• Vocals reside more in the mouth and throat and less in the chest of the speaker/singer.
• The high frequencies are more pronounced than the Amperex but less so than the Mullard 7DJ8.
• Bass is solid and articulate, not boomy in any way but there are times I wish it might have a bit more heft (an Amperex 7308 strong point).
• There is a “quickness” to the sound both starting and stopping when the program material calls for it.
• Drums have a little less resonance but higher pitched sounds such as the clacking of bamboo rods and wooden blocks are extremely realistic.
• Images are specific and clearly distinguishable although perhaps a little smaller.

In the final analysis, there is no single-best small signal tube just as there is no single-best car, wine, wristwatch, etc.  Much depends on set and setting.  Specifically, how we judge the characteristics of a specific type of tube will depend upon the gear being used, the room’s acoustics, and even our frame of mind.  That having been said, in my circumstances, the Telefunken ECC88/6DJ8 dual triode remains one of my very favorites tubes of this type.

Since I'm leaving the GEC KT88's in the Premier 11A for a while, I thought I'd focus on some small signal tubes used in the Premier 16LS2 preamplifier.

In the current review set, four of the Telefunken (TFK) ECC88/6DJ8 tubes are a matched set from 1968, made in the Ulm production plant for the German military.  They are packed in military boxes and bear the BWB designation (Bundesamt für Wehrtechnik und Beschaffung:  German Federal Office of Defense, Technology and Procurement).

Although not visible in the photograph, they display the Letters "BWB" and a falcon underneath.  The other pair, year made unknown, comes from the Telefunken Berlin plant. 

Military production tube with box
 

All six on the larger (left) and smaller (right) standard TFK boxes.  
Note the code starting with the letter "B" on the third and final tubes
which show they were produced in Berlin.

                                                                                                                   

All bear the TFK hallmark diamond molded into to the bottom of the tube between the pins.  Tubes marked as Telefunken that do not have the diamond were not actually made in the Telefunken plants.  For example, some tubes were marked as TFK but were made by Siemens, another German manufacturer.  You can distinguish these latter tubes by the seams (sometimes two, other times four) visible at the top of the tube.  These are very respectable tubes and you’d be lucky to have them even though they aren’t genuine TFKs.  The only other manufacturer with seams visible on the tube top is Amperex.  

Diamond molded into glass                                                                Amperex 7308 (left) with four seams visible and TFK with no seams (right)      

The TFK ECC88/6DJ8 tubes replaced a set of Amperex USN-CEP (US Navy-Commercial Electronics Philips, I think) 7308’s made in Hicksville, NY.  These Amperex 7308’s are among my favorites in the Premier 16LS2.  

 Amperex USN-CEP 7308
 

Most tube aficionados consider Amperex, Siemens and Telefunken to be the premier manufacturers of vintage European tubes.  Based on my limited familiarity with the company, I would add the Lorenz PCC88/7DJ8 made at their Stuttgart plant in the 1960’s to this august group.

In the next installment:  Are Diamonds an Audiophile’s Best Friend?

With all the reviews I’ve been doing lately of tubes in the KT88 family, I thought it’d be appropriate for another reality check.  So, I took out a quad of GEC KT88 tubes to give them a listen.

It’s become almost fashionable lately to bash the GEC KT88 as being not worth the money.  I’m not going to get into the midst of that argument.  I’m just going to describe how they sound to me and along the way, there may be some comparisons to other tubes, but that will only be in passing.  My intention isn’t to say what’s worth what.

The sample tubes were manufactured by the Marconi-Osram Valve Co. in England at their Hammersmith plant which is designated by the letter “Z” on the tube label.  They are the solid, black plate type with two side getters.  Interestingly, the getter splash screen is transparent (see photo below).  One tube is a 1972 vintage with a blue GEC label (see photo), two are from 1975 and one is from 1978.  All three of the latter have the amber label (also see photo).  The have a brushed aluminum-colored collar and a brown base.

Rear(?) of GEC KT88 showing Hammersmith "Z" designation                   GEC KT88 and its box 

Close up of transparent splatter shield                                                Newer amber label and older blue GEC labels

These tubes were intended for sale in Europe since those for US sale were labeled either “Genalex,” “Gold Lion,” or “Gold Monarch.”  This name-differentiation was due to the fact that it was felt “GEC” might be confused with the American manufacturing giant, General Electric.  In fact, GEC does stand for General Electric Company but it had absolutely no affiliation with the similarly-named American company.  I think this was a tempest in a teapot, but that’s only my opinion, naturally.

Listening Impressions:

• Smooth and delicate sound with treble transients integral to the whole without drawing attention to themselves.
• Excellent bass response with instruments such as the cello having a woody, resonant sound.
• Horns are burnished but can be blatty (I know that’s not a word, so live with it) when the recording calls for it.
• Voices and vocals are natural and almost life-like.
• Continuous sound stage but instruments occupy their separate acoustic spaces. 
• Effects such as studio reverb are easily distinguishable from natural reverberation.
• The “emotion” of the music is conveyed without effort (see examples below).
• Detail is abundant but never in your face.

I said I’d give some examples at how good these output tubes are at conveying music’s emotional content and here are three examples.  Two of the lachrymose kind and one just plain evocative.

While listening to Kenny G’s “Wedding Song” (no comments, please) I found that tears were streaming down my face without my even realizing what was happening.  Now perhaps the song was triggering some unconscious memories and associations, I don’t know.  What I do know is that the song was evoking such a strong emotional response, that my body was reacting to a stimulus I didn’t even know was there.

Second example.  I was watching one of Anthony Bourdain’s eat-fest travelogues and this one took place in Lisbon, Portugal.  Throughout the hour-long show, the music of a Portuguese guitar duo by the name of Dead Combo was featured.  These two guys played a type of Iberian-infused rock that I’d never heard before.  But it managed, somehow, to bring me back to my much younger years when guitar work by people like Jimi Hendrix, Carlos Santana, David Gilmour, Eric Clapton and a host of others spoke to me in a way that was personal and direct.  The Dead Combo didn’t sound anything like these guitar players, but the connection was there nevertheless. 

Final example.  A 27 year old Portuguese woman by the name of Arnauth Mafalda was featured for a brief sample of one of her songs.  She’s evidently quite popular in Europe although I’d never heard of her before and she sings in the Portuguese style known as fado.  I don’t speak or understand Portuguese:  its vocabulary and pronunciation are sufficiently different from the Romance language I know a little of that I can only pick out words here and there.  However, she sang with such emotion, such anguish that once again, I found the tears rolling from my eyes before I knew what the hell was going on.

Of the output tubes I’ve had in my system of late, only the Tung-Sol black plate 6550 and surprisingly to me, the Valve Art KT88 have left an impression on me that come near to the GEC KT88.  Each of those sound different, but then almost everything does.  They may come near, but for me right now, not all that close.    

Maybe my medication needs to be changed.  I don’t know.  What I do know is that with the GEC KT88 tubes in my system, there’s an emotional connection to the music that seems to bypass my head and go straight to my heart.  I may take a hiatus from reviewing other power tubes for the immediate future; I just don’t want to take these out.  

The final entry in my review of Chinese manufactured output tubes is the Valve Art KT100.  As is the case with its VA brethren, the VA KT100 is a three-hole, grey plate tube, with a chrome-colored collar and black base.  The tube has a single side getter positioned at the bottom of the plate, but in this case, the getter ring is uniquely fastened through the bottom oblong hole of the plate structure.

These tubes are still available through Analog Tubes for $94.25 per matched pair.  GD-Audio (aka Good Components) carries a Shuguang KT100A version of the tube, which appears to be of different construction, for $27.50 per tube. 

The review sample was purchased approximately eight years ago and had been previously broken-in, although not used in recent years.

VA KT100 Front View                                                                          Side View Including Getter 

NB:  As reality check, I had Tung-Sol 6550 black plates with the two side getters in the 11A for a few days just to refresh my sonic memory and remind myself what that standard of mine sounds like.  Two days later I also replaced the Voshkod 6H23π-EB small signal tubes in my Premier 16LS2 with Amperex USN-CEP 7308’s.  I then listened to that combination for an additional two days before switching to the Vale Art KT100’s in the Premier 11A.

Listening Impressions:

• There may be a little extra oomph (macro-dynamics) due to the KT100’s extra plate dissipation
• Percussion instruments are especially realistic
• Images solidly occupy their acoustic space and are nicely distinct from each other -- borderline excellent in this regard
• Although there is a decided sense of air around instruments, treble transients are more subtle and a bit rounded rather than sharp
• Low level detail is very good but not among the best
• Inner detail/timbre is borderline excellent
• Evenly balanced through most of the frequency range

In general, I found the VA KT100 to be musical, enjoyable and always at the service of the music.  While the VA KT88 remains my favorite in this group, the KT100 acquitted itself well.  The VA KT100 bears a strong resemblance to the VA KT88 sonically.  I’ve been pleased, generally, with the superior sound staging abilities of the various output tubes sampled in this series of reviews.

I had always thought, frankly, that the KT100 was somewhat “crude” sounding but this time around it has proven to be musical and surprisingly, really talented at conveying most of the music’s nuances and emotion.  Another winner from Valve Art.

How Does It Sound?

I’ve only used one power cord with the Hydra-8 and that’s the Shunyata Taipan Helix Alpha 20 amp power cord.  Therefore, I find it nearly impossible to separate the “sound” of the Taipan from that of the Hydra Model-8.  Although a good cord, the Taipan was the bottom model in Shunyata’s product line of Taipan ($700), Python ($1,200) and Anaconda ($2,000) power cords.  They have since been replaced with newer models:  the Zi TRON series Cobra ($995), Python ($1,995) and Anaconda ($2,995) and perhaps the closest, at least in terms of price, to the Taipan, the Black Mamba ($600).  The Black Mamba, as far as I know, doesn’t utilize Shunyata’s Zi TRON technology.

Please bear this in mind when reading my listening impressions of the Hydra-8 because in a very real sense, they are my impressions of both products.

That having been said, I did give the Taipan a well-deserved vacation recently back to its original home on the West Coast.  While there, the Taipan basked in the warm California sun and was also treated to an invigorating spa treatment via the audiodharma Cable Cooker.  I will, therefore, be able to comment on how my system sounded minus both products and when they were reintroduced, any changes I may have heard in the Taipan.

There was one other confounding affect to all of this.  Once the Taipan returned and the Hydra Model-8 was hooked back up, I also removed two Venom3 power cords (one from the Oppo BDP-95 and the other from the c-j Premier 16LS2) and sent them to the same spa in California for treatments of their own.  I realize that I’m breaking audiophile-approved rules left and right, but that’s what happens in real life.

After the Taipan and Hydra-8 were back in the system, my immediate impression was that of a smoothness to the sound that hadn’t been there during their absence.  Additionally, the bass was more weighty without the quality of the bass suffering from bloat or overhang. 

Over the three or so days it took for the Taipan to recover from its treatment, the system gained an added degree of extension in the high end of the frequency spectrum.  This was heard as a sense of air around instruments previously missing and a bit of extra detail to boot.  Two words that kept appearing in my listening notes were “subtle” and “delicate”.

All the while the power cord settled in, the smoothness remained and I attribute that primarily to the Hydra-8 itself because that was one of the characteristics I remember prior to all of the changes having been made.

Once both the Taipan and the Hydra-8 were back in service, the sound stage became deeper and its images a bit more solid.  One change I can attribute to the Taipan’s Cable Cooker treatment, was the shape of the sound stage.  Previously, the sound stage had been fairly squared-off behind and in the plane of the speakers.  Depending on the tubes in service, source, and material, the sound stage would extend to my listening position on occasion, in a triangular shape.  After treatment, however, the sound field near my listening seat has become, for lack of a better way of expressing it, more populated.  And not only is there more going on, but the shape of the sound field has changed also.  It’s now square further into the room and is more like a truncated pyramid at my listening position rather than a triangle.

This may sound as if I’m splitting hairs or counting dancing angels, and maybe I am.  But I don’t think so.  Something the c-j equipment has always done very well in conjunction with the ESL-989 speakers is project a three-dimensional sound stage.  As a result, I tend to pick up on auditory cues and changes in this regard pretty easily.  It’s one of the reasons I tend to focus on this aspect of my system’s sound reproduction as much as I do.  Perhaps to the detriment of other qualities such as evenness of frequency response, micro- and macro-dynamics, etc.  

I always find the portion of the review dealing with describing a subjective experience in a somewhat objective manner the most difficult.  There is always the tendency, I find, to read more into the experience than may actually be there.  Hopefully, I have enough listening time at this stage in the game that I’m able to recognize when that’s beginning to happen and I can prevent it.  But in the final analysis, other than using measurements that may or may not have anything to do with the actual listening experience, what can we do? 

I thought I would split the Shunyata Research Hydra Model-8 Power Conditioner review into two parts.  The first installment deals with the physical description of the unit and the second will cover how the power conditioner affects the sound of my system.

NB:  The material used for this part of the review has been gleaned from online sources.  The snide remarks, however, are mine.
 

Physical - Outside

The Hydra Model-8 measures 13"W x 9 1/4"D x 5 3/4"H and weighs in at 17 pounds. 

The fascia is ¼ inch aluminum and the chassis is also made of fairly thick aluminum painted a basic black.  Four rubber feet support this passive power conditioner that’s made in Poulsbo, Washington.

There is just one user-control and that is the on/off switch on the rear right side (as you face the rear) of the Hydra Model-8 just above the 20 amp IEC connector.  I guess the IEC connector could be seen as a second “user-control” since you get to pick the power cord.  There isn’t one included with the $1,995 (at time of purchase) unit.

Continuing with the outside of the Hydra Model-8, there are four duplex electrical outlets that are made to specification for Shunyata by Hubbell Incorporated in Connecticut.  The Venom outlets (I know, enough with the snake references) are triple-plated in silver and rhodium and are made by Hubbell without any ferrous materials and all carbon has been removed.  Once Shunyata gets their hands on the outlets, they are then cryo-treated.  

Although the Venom outlets appear correctly oriented to me with the grounding plug below the twin electrical blades, the Hubbell name reads upside-down on the top of each outlet.  The Venom outlets are also grouped in two pairs for analog and the other two for digital sources.  Presumably the internal wiring is also separated to prevent noise from the digital outlets from entering the analog ones.

Physical – Inside

The Venom outlets are housed within a separate enclosed chamber inside the Model-8 and are surrounded by Shunyata’s proprietary Fe-Si 1002 ceramic compound.  This is said to passively reduce electromagnetic interference in a way similar to ferrites although it has no metallic content.  That being the case, I think including “Fe” (the chemical symbol for iron) in the name of the compound causes confusion.  Unlike ferrites, FeSi-1002 does not dampen high frequency energy, blunt transients or darken the overall sonic landscape, according to Shunyata.  And, they make a slithering sound when you move or shake the unit.

The Hydra Model-8 utilizes a three bus layout, each weighing two pounds, made from pure CDA-101 copper ingots.  This is the same copper that Shunyata utilizes in all their products.

The passive power conditioning is comprised of a three-prong approach, appropriately named the Trident Defense System.  Besides being the name of a US submarine launched ballistic missile, there’s a Trident Bangor Base located a few miles from Shunyata’s Poulsbo facility.  And finally, the trident is the logo for the Italian pasta rocket manufacturer, Maserati, which can’t hurt your image.  So we have three phallic symbols wrapped into one product:  snakes, missiles and cars.  I wonder who comes up with their marketing?

As you might expect the Trident Defense System (TDS) encompasses three parts. 

First, there's the Venom filter, Shunyata's four-element capacitive array designed to eliminate over-voltage spikes of only a few volts to beyond 1,000 volts on transients. 

Second, there is a six-element array of thermal metal-oxide varistors (TMOVs), that provides 6,000 volts of over-voltage protection and up to 60,000 amps of peak-current protection. The TMOVs are, according to Shunyata Research, "next-generation devices" -- "20mm varistor discs that have integrated, internal thermal protection" and can't "explode or catch fire in the rare event of a catastrophic over-voltage condition."  I would hope not.

Third and finally, the Hydra Model-8 uses a Carling electromagnetic circuit breaker with large-surface-area contacts to allow for unrestrained current flow but also shut down in the event of over-current episodes that exceed 20 amps.

For those of you who have made it this far (thank you), I’m not sure what the difference is between 60,000 amps of peak-current protection versus 20 amps during over-current episodes, but then I’m no electrical engineer.  Shunyata Research also points out that the Model-8 is rated for 2,400 watts of continuous power delivery.

Next installment:  so, alright already, how does it sound?