They say the "HERD" is almost always wrong. Presently, the audio herd is buying into the more "Power" paradigm with
regard to output power tubes. Let me be honest here, I have not tried the 120 or the 150. However, I have used the the
New Sensor Corp. Genalex KT88's for the last few years. In my opinion, more power doesn't necessarily translate into
better sound. However, the audio pundits will have you believing it does. This Blog establishes the Output tube change to
my VTL Stereo 90 that in my opinion, contributed synergistically to the incredible sound I achieved swapping my Ge 5
star triple mica 6201signal tubes with the Telefunken Long Plate 5965's from my previous Blog on this rare tube.
Before I expound further on the Output tube change to my amplifier, I want to communicate a few poignant points that
I neglected to touch on in that previous Blog. (1)The main differences between Long Plate tubes and Short Plate
tubes can be summed up in 3 words: 3D, Lively, and Open. (2) The 5965 tubes are computer tubes and (3) The 5965
tubes draw more heater current than a 12AT7.
Several years ago, I bought my VTL Stereo Ultra-Linear which had Ge 6550A output tubes and Ge 6201 signal tubes. In
spite of fact that I enjoyed the sound of the 6550's, I bought into the audio hyperbole of the greater power of the KT88's
will enhance your sound and re-tubed my amp with the New Sensor Corp. KT88's. Further more, the Gec/Mov KT88 has
been lauded as the King of Output tubes and the New Sensor Corp. Genalex current Russia production tubes are
marketed as the closest you can sonically come to the sound of the iconic Gec/Mov KT88. In addition, I changed my
input signal tubes to Siemens 801s and my driver tubes to Ge 5 star black plate triple mica 6201.
Recently, I lost my right channel from a KT88 tube gone bad and I decided this would be the perfect opportunity to have
my amp inspected and if needed, upgrade capacitors, resistors, etc..... A good friend of mine who has the iconic Marantz
7c pre-amp had his technician totally restore his pre a few months ago. I was extremely impressed with the quality of the
work and this is the person I decided to use for my power amp issues.
He called me a day later after I dropped off my amp to him and informed me that the filaments in one of my tubes had
touched and damaged my board which knocked out my right channel. I asked him what his impression was of the
KT88 output tube? He replied with the following question: What type of music do you listen to? I told him jazz,
classical, blues, R&B and rock with jazz, blues and classical the priorities. He then went on to tell me that the KT88's
exaggerated the frequency range between 4.5 KHz-6.5 KHz which gives the majority of instruments an unnatural
sound. Only a few instruments sound natural in this frequency range. He went on to say that the tube envelope
design, which is indented towards the top of the envelope, pushes the high frequency spectrum to an almost bright level.
In contradistinction, he told me the 6550's straight side envelope provides a more organic, even-handed presentation,
better transients, and a more relaxed sound. He replaced my electrolytic capacitors, replaced the cheap Chinese resistors
with higher quality, re-soldered my board and changed my RCA inputs to gold plated ones. In addition, he rejuvenated
my KT88's and brought them back to 80%.
I still had my original Ge 6550A output tubes and brought them with me when I went to pick up my amp. My tech
tested them and they all tested strong. At this point I decided to have him take out the KT88's and put in my original
6550's. I decided not to go back to my original signal tubes and kept the Siemens 801s and 5 star Ge 6201 in the
input and driver positions. Listening sessions corroborated the tech's opinion. The overall presentation with the
6550a's just sounded purer and more real than the KT88's. Let me be clear and say that the Genalex re-issues
presented a very decent sound for current production tubes. However, in my opinion, the Ge 6550's are unbeatable.
Tones are richer, and transients have greater impact across the entire frequency range which imparts a greater
realism and completeness to the musical presentation.
In conclusion, replacing the KT88's with the Ge 6550's and swapping the Ge 5 star 6201's with the Telefunken Long
Plate 5965 has resulted in an inexorably addictive sound and not until I can no longer source NOS 6550's will I
change my Output Power Tube direction. What can I say? At this moment in time, as well as the foreseeable future,
I'm not following the "HERD".