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dkevin

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  1. https://www.youtube.com/watch?v=XbtiZLHJQwg
  2. I realize this thread is very old but I ran across it just this morning...I have replaced OT's in Gibson amps that used 2 6v6's in parallel output/single-ended configuration with an OT from Allen Amps. From the Allen Amps website: "TO11S Heyboer output transformer rated 4,000 ohms primary to 4 or 8 ohms secondary. It is the same as the above TO11C but mounted on its side the short way to prevent transformer coupled hum. It will now be the standard OT for the 10W Chihuahua. Excellent choice for a 6L6 or EL34 single-ended amp using either a 4 or an 8 ohm speaker load. 3-1/8" mounting centers. It is the same physical size as my TO22 transformer"
  3. It appears to be an early GA-5 without the "Skylark" designation that has 2 inputs added by a modifier. I can't think of why you would need 2 more inputs for a 5 watt amp...The cabinet is the earlier variant with larger edges at the top and bottom of the face. These amps are great! Congrats!
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  5. I know it would be cooler looking to have the original interstage caps for appearances sake...but I think almost all of mine were found to be leaky. I chose expensive caps (Auricaps) for one amp ... 716P orange drops for another and I think I used Mallory 150's for a third. None of them sounded bad but they all had unique tone. It sounds like you are moving cautiously and thoughtfully...that is a very wise thing to do.
  6. One of these days I'm going to learn how to place links in my replies...but...until then...I used Google to find Paul Ruby. His website has a tech section. In the tech section one of the first things he covers is "I finished my amp and now I want to power it up for the first time". I am learning how to work on tube amps from the generous help of more experienced people. I started up by purchasing very simple amplifiers that needed to be repaired. I gravitated to Gibson amps because they were not (at the time) in high demand and I could get a fixer for $100 or less. Diagnosing problems and repairing tube amps requires focus and attention to detail. I don't know about you, but these two things do not come naturally to me. And just about the time you start to think you've seen it all, along comes a real head-scratcher that really humbles you. I hope your amp gives you many hours of joy! John King is another Tweed Skylark fan...he wrote several articles about them. When yours is up and roaring, you'll be amazed at how un-Champ like this simple 3 tube amp sounds.
  7. Looks like you got a real gem there! I have found a few unmolested examples and a couple of badly hacked ones too. These amps are fairly logical in layout and use a minimum of parts. Gibson was fond of the cardboard "party-caps". In the more thrashed examples this large cap is pimpled or fairly near-bursting open. I usually replace it with individual F&T caps. The cathode bypass caps are a must-do. I usually replace badly drifted resistors as required. The interstage caps may hold up or they may fail as the amp is powered up. I try to keep them if at all possible. Do you have a tube tester? If not, you may want to use a known-good set of tubes to start the amp up. It helps to eliminate some of the possible points of failure before you plug it in and smoke-test it. Paul Ruby has a very good start up procedure for tube amps after repairs. I think he recommends starting up without tubes-checking AC voltages (high voltage windings/5v filament and 6.3 volt heaters) from the power transformer at the 5Y3 socket and the 6V6 socket. Only after these voltages are verified does he proceed to install the tubes and continue the testing.
  8. Actually there are two GA-19RVT's with slightly different schematics. The early one has a rear-facing chassis (like a 5E3) and uses a 7199 tube as the reverb driver. This amp is very highly regarded for its tone. The later (Crestline) variant uses a 6C4 to drive the reverb and has a forward facing chassis. This amp (yours) has a rep for sounding thin and lacks volume. However, the reverb and the tremolo are still considered to be awesome. When you look for the GA-19RVT schematic, the 7199 version is probably the one you will find. If you download a copy of the M-216RVT (Gibson-Maestro version of the Falcon) it will be the correct version for your amp. (I use EL-34 World's Tube schematic page). Just check that the 6C4 is used for the reverb. Even if you are not planning to learn tube amp maintenance, having the schematic and being able to identify the problem parts is important. I have found that Gibson used a few "labor-saving" devices to speed production. One of these is a tone network that looks like a small piece of orange taffy with three wires protruding from it. This is a collection of resistors and small capacitors sealed in epoxy and attached to the volume pot. As new, it probably functioned well. But 50-60 years down the road, it is one of the reasons why this amp lacks oomph. This network is but one of several pinch-points in the amp. If you are content with the sound of this amp (as-is) then there is no reason to worry yourself further about optimizing the circuit. The advice given you about replacing the two wire cord (removing the death-cap)and updating the electrolytic capacitors is sufficient to protect it (and yourself) for the time being. Enjoy!!
  9. Congratulations on your amp find! I have a couple of these amps and they are great. Yours appears to be the later Crestline Falcon from 62 or so. Sometimes people will trash them for sounding thin and lacking volume. I think your wariness about finding a trustworthy tech and the $ involved in sorting out the issues has merit. I am somewhat surprised that the amp sounds as good as you say without any attention. If it is playable, you have several options. You can sell it as is.. or you could have it checked out by a local amp tech. It would cost you some money to do so but at least you would know what you have and prioritize your repairs. The 3-wire cord can be done when the tech is checking things out and should not be a huge expense. The reverb hum could be as simple as a tube (or cable) or as complex as replacing individual components. As others have advised you, the electrolytic capacitors (if original) are living on borrowed time. If they fail, they can take out your tubes and transformers. Gibson was infamous for using the paper "party" caps which according to some, was a bad idea from the get-go. The cost factor is why I started working on my own amps. There are a lot of helpful people (and a few not-so-helpful) who can advise you and help you learn. Ultimately, only you can decide whether this course is right for you. It is not easy...nor is it simple (as some have stated) but it is an excellent way to own, play through and maintain tube amps that otherwise would be out of our reach.
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