"Keep a good head and always carry a lightbulb."
Tubes
I just bought a Vox AC50 (hooray me!) and was wondering if anyone had any advice on tubes. I switched out the Ruby EL34 power tubes for a set of Electro Harmonix 6CA7's, and it sounds a lot better.. much warmer and a lot less harsh. However, I was wondering if anyone had any recommendations or knowledge about tubes, and which ones had particular characteristics. Any advice would be most appreciated!!!!
# 1
Hi Silvervox,
Great amp. Congrats!
Not only many years as a musician (just applied for my pension from the AF of M), but I had the good sense to obtain a degree in Electronics and have spent years re-furbing vintage tube amps. Here's my two pennies worth.
I've had customers that prayed to the Groove Tube gods and the list goes on from there. However, it's been my experience that one of the most consistant and reliable tubes on the market is Sovtek. Yep, plain old cheap Sovtek. Never had a complaint from a customer.
I asked an Engineer once why, of all products on the market, why the Soviet made Sovtek tube seemed to out perform all others. His reply was, "Think about it....The tube is the Russian "State of the Art". The Mir Space Station was full of them. Go figure.
One more thing.....The key to life on any tube amp is the Bias adjustment. That makes all the difference in the world on the sound of the amp, regardless of the tubes used.
To set the Bias on an amp I use a "dummy" load instead of a speaker (to save the ears) and monitor the output on an oscilloscope while inputing a 1k sine wave at near full volume. A super clean Bass amp (SVT for example) should have a near perfect sine wave on the output (no "crossover" distortion).
Guitar amps are a different animal. Some crossover distortion is warranted. And, the ammount of crossover distortion determines the ammount of "crunch" the amp delivers. For example, with a 99.9% success rate, I'll ask a customer if they would like a Blues type "it crunches when you dig in to it", or Hendrix or anything in between. Over the years I can look at the ammount of crossover distortion and deliver exactly what the customer is looking for. Hope you have a good repair shop in your area.
Oh, if your so inclined, you can adjust the Bias by ear. I've had to do that on a gig after blowing a tube in "mid-show".
The main thing is have fun and enjoy the AC50.
db
Great amp. Congrats!
Not only many years as a musician (just applied for my pension from the AF of M), but I had the good sense to obtain a degree in Electronics and have spent years re-furbing vintage tube amps. Here's my two pennies worth.
I've had customers that prayed to the Groove Tube gods and the list goes on from there. However, it's been my experience that one of the most consistant and reliable tubes on the market is Sovtek. Yep, plain old cheap Sovtek. Never had a complaint from a customer.
I asked an Engineer once why, of all products on the market, why the Soviet made Sovtek tube seemed to out perform all others. His reply was, "Think about it....The tube is the Russian "State of the Art". The Mir Space Station was full of them. Go figure.
One more thing.....The key to life on any tube amp is the Bias adjustment. That makes all the difference in the world on the sound of the amp, regardless of the tubes used.
To set the Bias on an amp I use a "dummy" load instead of a speaker (to save the ears) and monitor the output on an oscilloscope while inputing a 1k sine wave at near full volume. A super clean Bass amp (SVT for example) should have a near perfect sine wave on the output (no "crossover" distortion).
Guitar amps are a different animal. Some crossover distortion is warranted. And, the ammount of crossover distortion determines the ammount of "crunch" the amp delivers. For example, with a 99.9% success rate, I'll ask a customer if they would like a Blues type "it crunches when you dig in to it", or Hendrix or anything in between. Over the years I can look at the ammount of crossover distortion and deliver exactly what the customer is looking for. Hope you have a good repair shop in your area.
Oh, if your so inclined, you can adjust the Bias by ear. I've had to do that on a gig after blowing a tube in "mid-show".
The main thing is have fun and enjoy the AC50.
db
# 2
Wow, thank you.. I never would have guessed Sovteks, and probably would never have tried them.. I had my eyes on these big, expensive, gold-plated tubes (In typical new-owner fashion, I'm very protective and will only settle for the best... lol) but now I'll just fill my spare case with the Sovteks. 5 for 45 bucks? I was about to spend almost that much for a single tube! Anyway, thank you for your help, DB. Good luck with your retirement, and remember to stay busy! I heard from a very reputable source (Kill Bill Volume 2) that the number one killer of old people is retirement. Lol anyway thank you again.
"Keep a good head and always carry a lightbulb."
# 3
