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Hi, I'm new to the forum. I'm in my early 60's. First and foremost, I have VERY basic radio skills and tend to be more automotive/mechanical. I had my Grandparents Philco F-1902-121 Hi-Fi (they bought it new) gone through locally by a very sharp young man. Tubes checked, replaced some transistors, capacitors, and cleaned pots. It all works. I had'nt heard it in 40+ years but I am sure that the unit used to have bass that would literally rattle the windows. Am I imagining this? It is not capable of that now and at higher volume and bass levels it make the sound quite distorted/fuzzy/muddy. He repairs many very old radios, but I don't think he is aware of this ones potential as he isn't real familiar with them. He thought it might be that the 2 larger tubes (T-6L6GB-PSV) were not "matched" so 2 new "matched" tubes were installed. It may have helped some but it is still way off the mark sound wise on records and radio both. I will say he did check the 15" speaker for damage and said there was none. Could the speaker still be lacking in some way? I could divert the 15" speaker wires to a boxed speaker for testing if needed. The treble is handled by an electro static amphitheater which sounds pretty good. I will add that Grandpa did replace a socket for one of the aforementioned tubes and the remaining one you have to wiggle the tube to make it glow intermittently. Even if they are glowing could there be high resistance in either of those sockets causing an issue? I am capable of soldering new ones in if needed. Also there is a slight hum to it. I'm not sure if that is normal but I could add a grounded power plug (ground the 2 chassis's) if that might help. Again, I don't think I am imagining how rich it used to sound and am looking for suggestions on how to get it back up to snuff. Thanks! Dave.
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Welcome to the Phorum, Dave! Let's address the issues you've brought up. Loose tube socket pins can cause all sorts of issues. Try cleaning the pins with Deoxit and tighten them up a little by gently squeezing them with needlenose pliers to try and eliminate the contact issues. This unit is 66 years old. Replacement of all paper/electrolytic caps and out of tolerance resistors should be done. Try cleaning the speaker with compressed air to remove any dust bunnies and see if that helps. There is also a selenium rectifier in the tuner that should probably be replaced. Lots of help available here from our members with your project; just need to ask. Take care and BE HEALTHY! Gary
P.S. You may want to look into the local source of assistance also available to you. The Iowa Antique Radio Collector Club.
www.radio-collector.com
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Gary - Westland Michigan
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10-4 on the sockets. So, if the speaker works at all and the cone is not ripped and is clean the issue is most likely not the speaker itself? I will double check with my repair guy but the repair order does say 28 capacitors and 20 resistors and 1 diode replaced.... Again,sound quality issue is with radio and turntable both so I can assume (maybe incorrectly) that it is something that both utilize. Thanks again and look forward to more ideas.
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Welcome to the Phorum Dave. Your speaker is still suspect. The cone is made of paper and over the years it is exposed to humidity and temperature changes causing possible slight warping. This will shift the voice coil to the point of rubbing on the magnet pole. Sometimes a person can feel or hear the rubbing when gently pressing the center of the cone in and out. You will also get a rubbing if the gap of the voice coil becomes dirty or has other particles. The easiest way to check is to substitute another known good speaker.
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To re-iterate what Gary and Rod have said, and to add some:
1. This sharp young man, when did he go through the radio? Attributing distortion and lack of base to non-matched 6L6 to me is superficial.
2. Has he replaced ALL the paper tube caps and the electrolytics?
3. The speaker could be easily checked with an audio oscillator and any amp (this radio likely uses a perm magnet type so it is easy).
4. What kind of rectifier is used in the radio?
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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Hi and welcome,
You could use a scope and an audio generator to "sweep" thru the audio stages to see where the distortion is and what the frequency response is like.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
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