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Commentary: affordable tubes

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This quarantine has been difficult and although I do play records a lot during the day, I’ve needed some other things to do audio-wise. So, I have been changing things around in my stereo: swapping cartridges, rolling tubes, and even substituting different electronic components.

In this article, I am writing about my experiences and the resulting preferences for various power tubes I have used over the past 12 years. I am focusing on inexpensive brands as opposed to the more esoteric offerings. The brands used were mostly manufactured by JJ and, to a lesser extent, Sovtek and Electro-Harmonix. All tubes were purchased from

My system: The turntable used is the AR “The AR turntable” with a Sumiko Premier MMT tonearm that is played through an NAD PP1 phono stage. The phono cartridge is the Hana EH moving coil. My digital gear consists of an Audio Alchemy transport and Audio Alchemy D/A converter. The tube line stage is the Antique Sound Lab Line One with a single 12AU7 tube. The power amplifiers are a pair of Quicksilver Mini-Mite 25 watt tube power amplifiers. These drive the Acarian Systems Alon 1 speakers. AudioQuest speaker cables and interconnects are used throughout my system. My records are cleaned regularly with a Nitty Gritty vacuum record cleaning machine. My Antique Sound Lab line stage inverts polarity, so I reverse the speaker cables although I am not sure if I can really hear the difference.

I started my tube power amplifier journey based on a discussion with fellow Dagogo writer Marc Silver, ex-owner of Soundscape Audio & Visual. Marc suggested a pair of Quicksilver Mini-Mite 25 watt mono blocks. I had some concerns that 25 watts would not be sufficient to drive the 87 dB Alon speakers, but Marc assured me that there would be enough power for my needs and the tube sound would be spectacular. I had to take Marc at his word because these amplifiers are not readily available to audition. My pair was drop shipped from the Quicksilver factory. When I first listened to these 25 watt amplifiers, I knew that not only was Marc was absolutely correct about the power but also about the sound: my Alon’s were elevated to a whole new level. These were the best power amplifiers I had ever owned. The Quicksilver Mini amplifiers each come with a single 12AX7 and a pair of EL34 output tubes. These amplifiers are auto-biasing and can use KT88, KT77, KT66, 6L6 and 6550 tubes, making it easy to compare the differences. Also, unlike a number of tube amplifiers, the power output of 25 watts does not change no matter which tube is used.  Quicksilver does recommend matched pairs for each amplifier. All of the tubes I tried were used for many hours over the years.

The Quicksilvers came with EL34 tubes, so this will be my first description. The three-dimensional sound with such rich lushness that gives you the impression you are listening to live music was something I noticed right away. The soundstage and image had a wide open sound that I feel can only be achieved with tubes. The one drawback of this tube was the attenuation of the frequency extremes, especially the bass. Tubes can vary in their lifespan and the original EL34s only lasted about a year before I started having problems with them. One channel would intermittently go out. Quicksilver checked out the amplifier and said there was nothing wrong with the amplifier and the problem ended up being a malfunctioning tube. I have found tubes can go bad in different ways, from a channel intermittently going out to a weird light show. Usually I seem to get about 2,000 hours from output power tubes.

Enter Tube Depot. Mike Sanders, the owner and designer of Quicksilver, suggested I try the KT77, which has a similar sound to the EL34 but with a more robust bass. This ended up being my favorite pair of power tubes. I purchased these tubes from Tube Depot and since the amplifiers are auto-biasing, it is easy to swap out the tubes. The sound of the Quicksilvers with the KT77 was very similar to the EL34 but with much more satisfying bass. The resolution may have been a bit more pleasing with the EL34, but the better bass made the KT77 my favorite.

Tube Depot carries a variety of tubes and offers free shipping on orders over $99 so I decided to experiment by ordering a variety of tubes. The customer service employees know their tubes and suggested I try the 6L6. These tubes had a little bit different presentation; however, the bass was similar to the KT77. The midrange was comparable to the KT77 with maybe a touch more presence. This was a very enjoyable tube that was right up there with the KT7 as my favorite. The wide open sound connects you to the music in the same way as the KT77. You can save a little money buying a pair of 5881 tubes, which is like an economy version of the 6L6.  The 5881 had a similar sound to the 6L6 at a more economical price, although I would spend a little more and buy the 6L6 as the price difference was not very much.

The most expensive tube that I tried was the KT88. Mike Sanders from Quicksilver told me that even though this tube will work in my Quicksilver Minis, he designed these power amplifiers around the EL34 tube, so he did not think I would enjoy the KT88 tubes as much. While the KT88 was the most linear and had bass similar to the KT77, it was not as musically engaging as the KT77 or the 6L6 and it was the most expensive. The midrange with the KT88 seemed a little more forward and the top end was a little bright. It still had the tube sound, although it seemed a little closer in sound to a solid state amplifier. I even preferred the sound of the EL34s with their bass limitations, and they are less than half the price of the KT88s. See what happens when you don’t listen to the experts?

In summarizing the sound, the KT77 and the 6L6 tubes were the best balanced and, with the more complete bass, were my favorites. The EL34 had the pure midrange that gave me that tube magic and some people may prefer this tube, despite the rounding of the bass. These three tubes were the ones I have reordered and have been using.  The KT88 may be preferable in some applications, especially if you prefer a more extended top end. However, my Alons are already a little bright and the other tubes cost less, making the decision easy for me. I definitely enjoy the sound of tubes no matter which tubes I used — even the KT88s. The characteristics of each tube were closer in sound to each other in my Quicksilver Mini amplifiers than they were to any of my solid state amplifiers. There are many inexpensive tube amplifiers available and, for those who haven’t tried tubes ever or in a long while, they may give you a whole new listening experience. Sure, it may be a little more work, but once I went with tubes I never looked back.

Tube Depot regularly has specials, so I stocked up on tubes and now have enough to last me for at least the next 10 years. They really know the tubes they sell and were very helpful every time I called, even though their focus seems to be more on guitar amplifier tubes.


Copy editor: Dan Rubin


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2 Responses to Commentary: affordable tubes

  1. nickolas says:

    the recent JJ EL34L ‘s have all the EL34 magic with improved bass

  2. Jon says:

    Have you tried the Genalex Gold Lion KT-77 reissues yet? Those are the best current production EL34 variant I’ve found.

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