QuestionQUESTION: I have a very old turntable that uses vacuum tubes. It has not been used for I don't know how long, and I need to get the layers of grime off the components. What would be the best way to eliminate the built up dirt? Also, I've heard that there is a difference in sound in equipment that uses vacuum tubes and equipment that doesn't; is this true? Finally, I was wondering how I would go about changing the system to play from a 3.5mm jack. I found the plug that connects the turntable to the amplifier, which is a three-pronged plug. How would I go about adapting this?
ANSWER: Hi Max-
The method I would suggest for cleaning these components is:
- Using compressed air (you can buy it in an aerosol can at an office supply or computer store), blow the loose dust and dirt off the components
- Whatever is left behind, you should be able to remove with rubbing alcohol and q-tips. The alcohol is ideal because it evaporates at room temperature and won't leave any residue.
There is a difference in how equipment sounds depending on whether it uses vacuum tubes or transistors. Vacuum tubes, or valves, are said to make the sound "fat" or "warm." As with many things with audio equipment, it is very subjective and very much a personal preference, and as transistor technology and circuit designs get better and better, the differences are less and less noticable. Wikipedia has this to say... "In general terms the sound from a tube amplifier will typically have a softer attack and the bass frequencies will be more prominent giving a warmer and less "harsh" sound. Instrumentation such as pianos and vocals sound softer and "fatter" than with transistor amplifiers. But as noted the reasons for these effects are not simply and unavoidably related to the gain device type, today a good designer using either technology has to make synergistic design compromise choices. And the sonic differences are less stereotyped than they used to be as a result."
Your three prong plug is most likely an XLR or mini XLR (sometimes called DIN) plug. You can get adapters to convert this to 1/8 mini / 3.5mm jack. If it's *not* an XLR or mini XLR, it's probably some weird proprietary connector, and you may not be able to adapt it easily unless you do a little bit of soldering. If you go this route, you will have to experiment until you figure out what each pin does. Most likely, the pins correspond either to left/right/ground or +/-/ground, but it's impossible to tell unless you fool around with it.
Hope this helps!
-Steven L Smith
---------- FOLLOW-UP ----------
QUESTION: First of all, thanks for the fast and very helpful response. I had just forgotten to ask how to clean the vacuum tubes. I'm also supposed to use the rubbing alcohol for the best result, right? Also, where could I get spare vacuum tubes?
AnswerYes, use good, clean Isopropyl alcohol (96-99% pure if possible; DON'T use rubbing alcohol - it contains minerals and oils that tubes don't like). You can use Q-tips with the alcohol- the wood ones work best because the paper ones usually can't withstand the pressure you'd be applying.
Sometimes the easiest way to re-establish good contact for the pins is simply removing the tube and putting it back in! This often cuts through the oxidation and re-makes the contact.
Tube sockets should be cleaned as well. Pipe cleaners work fine for larger-pinned output tube sockets.
It helps to wear rubber gloves when handling tubes... the oils in your skin can cause the tubes to crack when they get hot.
Spare vacuum tubes are difficult to come by, but there is an online store tubedepot.com that may have replacements for you.
