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I have a dilemma and am once again seeking advice.
I have a Sears Silvertone amplifier. It dates to the early 60's. Here is the dilemma. It needs new tubes, which I can replace through E-Bay. Since it is so old I wonder if I am taking a chance on blowing the transformer by replacing them?
I doubt I could find another transformer. Part of the sound of the amp is because of the old tubes. Sure would hate to destroy one of my prized possessions.
Help!!!!
I don't know the answer, but I sure would be careful.
Maybe have a music shop check it out first?
Thanks for the concern Backstop. I worked at the local music shop for 10 years.I should know what to do but I am stumped.
It is truly a dilemma.
With the increasing arthritis in my left hand I doubt that I will play in a band setting anymore. I am hoping to leave the Silvertone to my son as part of his meager inheritance.
I am looking at around $80 worth of tubes, I have no idea what the cost of replacing the transformer would be. As it sits now the amp is worth around $500. As it was my first amplifier to me it is priceless. Being able to pass it on to my son in working order would be indescribable.
Man, that would be great.Quote:
Originally Posted by Luke
Wish I could offer some advice but I don't know enough about tube electronics.
I'll bet Rick knows! :D
Barring that, maybe check around for a local Mom-N-Pop TV/electronics repair shop. Preferably one that has been around for a good long while.
No... you are not taking a chance.Quote:
Originally Posted by Luke
You can still, I believe, order vacuum tubes through Radio Shack if you go online. At least you could last year.
What are the tube numbers? Do you KNOW for a FACT they all need replacement? What are the symptoms?
I can probably help you trouble shoot it. Simply audio amplifier with tubes. Easy stuff.
Tell me the symptoms.
Power tubes/6L6's glow with normal blue haze.
6CG7 X2 occasionaly get noise, a gentle tap on the side of the tube stops the hum
12AX7 X3 one of the three also gets noise
My concern is that by replacing the tubes I would put more of a load on the transformer. I don't know if transformers denagrate with time. I know they are not under a vacum like tubes.
I need more information on this "normal blue haze" because that's not normal for a 6L6. Those are actually horizontal oscillator tubes. They are multielement tubes and are used as amp tubes (usually class C type amps, you're using them as audio Amps so probably class A or AB)Quote:
Originally Posted by Luke
Microphonic tube (of a sort, usually when you tap on one that is bad you'll hear the vibration in the amp). Sounds like this one should be replaced.Quote:
6CG7 X2 occasionaly get noise, a gentle tap on the side of the tube stops the hum
12AX7s are triodes if I REMEMBER correctly - used probably as the preamp before the 6L6s. (The 6L6s are the BIG tubes, right?)Quote:
12AX7 X3 one of the three also gets noise
This is not a concern. Replacing the tubes with properly operating tubes will not load it down MORE, but should make it function CORRECTLY. As to loading down the transformer (are we talking about the AUDIO transformers feeding the speakers, or the AC power transformer that is drawing power)....this should NOT happen unless you have bad impedance speakers (wrong impedance for those speakers) or your AX transformer is BAD to begin with (which I DOUBT on old tube equipment).Quote:
My concern is that by replacing the tubes I would put more of a load on the transformer. I don't know if transformers denagrate with time. I know they are not under a vacum like tubes.
Does this help?
On the "glowing blue haze" - this typically means one of two things. The first isn't so bad and that's perhaps the tube is running a bit hotter and higher voltages than normal - however, this should NOT be the case.
The other thing is you might have a tube that has gotten air in it. This can happen over time with old tubes because they just start to fail. If you're getting blue glow that means the tube is PROBABLY bad.
See Luke, told ya. :D
"This is not a concern. Replacing the tubes with properly operating tubes will not load it down MORE, but should make it function CORRECTLY. As to loading down the transformer (are we talking about the AUDIO transformers feeding the speakers, or the AC power transformer that is drawing power)....this should NOT happen unless you have bad impedance speakers (wrong impedance for those speakers) or your AX transformer is BAD to begin with (which I DOUBT on old tube equipment)."
Thanks a bunch electron guru! I feel confident that replacing the vacum tubes will solve all the issues I have with the old Silvertone! I thank you for the comments. The old Sears will rock on!
With luck you won't have to spend much money on tubes. Seriously try RS (internet) and look up Allied Radio ( I THINK they are still around)
Try Sayal Electronics too. I checked Mouser Electronics and Digi-Key but they don't seem to carry tubes.
UPDATE; The new tubes must have helped as Ms. Luke is most upset with new found volume!;)
/snickersQuote:
Originally Posted by Luke
I forgot to tell you about the side effects.