You're obviously a more than competent tech, but what I'm most impressed with is your attention to detail. Deburring chassis holes and not using transformer bolts as grounds are some things most techs wouldn't bother with. Good work sir!
This may be the best tube amp restoration video I've seen on RU-vid. Thank you for the demonstration, explanation, hypothesizing and testing. Pretty inspiring to watch and consider what you are doing and why all along the way. (:
I really like the uncluttered layout of this amp. The caps and resistors are readily accessible, and not buried way down in the back corner under a bunch of other stuff. It's a nice amp!
I have a Scout and two Epiphone Galaxies from this era, they are three of my favorite amps. The Scout/Galaxies also use the 6AQ5 tubes. I always thought the 6AQ5 was more similar to a 6V6 than a 6BQ5/EL84, like a small bottle 7-pin version of a 6V6. However, unlike 6V6s and EL84s, there are tons of relatively inexpensive NOS 6AQ5s out there which makes it affordable to compare brands.
You are correct. The RCA tube manual lists the specs for the 6AQ5A as being equivalent to the 6V6 except for maximum voltage and power dissipation, And the transfer curves for the 2 types are virtually identical. The 6AQ5 is listed as a beam power tube, same as the 6V6, but the EL84 is a true Pentode with a suppressor grid. The beam power tube design was the result of RCA's effort to get around the Phillips patent on pentode tube design. The 6005 W is the military and industrial ruggedized version of the 6AQ5A.
I love the deep dive on the Skylark. I sold my 64 and now have a 61. I have found that if you roll the tone on the SG back to 8 the 6bq5 Skylarks, fatten up very nicely.
Well done, sir. Another fantastic video and explanation here! There are a few schematics for the GA-5 Skylark. Gibson originally designed these without that T filter per schematics I've found. I have three of these amps and was able to compare versions against each other and the original spec, without the T filter, are the best sounding GA-5's in my opinion. A bit more low end, yes, but the mids are also fuller and the amp breakup at 10 just rocks. That said, originality plays a hand in how these are serviced and originality outweighing "tonal improvements" is smart. The 6AQ5's are surprisingly sweet sounding power tubes. I really love these GA-5's for some insane reason.
Can't blame the brittleness of stock speaker on not being broken in😂 Great information about the caps👍 Glad the tornadoes have left you in one piece 😎👍 Heard that the new Supro low wattage amp "Amulet" has somehow been able to eliminate the hum that seems to be part and parcel of low wattage amps...?
Great work as always, plus a good explanation. I liked it through the 2x12 cab. Kinda tinny with the original speaker and I have my doubts that the mounted baffle will be much better. Could be just some VC rub or just not a great speaker. Some old speakers sometimes used Kraft paper VC formers. When exposed to humidity and temp differences over many years they can malform. Either way, that seems to be the amps major drawback as it sits now imho.
I suspect they may have used hide glue or something similar on some of those 1950s and early sixties vintage speakers. The glue holding the voice coil former to the cone has a tendency to crystallize and become brittle leading to dropped or misaligned voice coils.
I admire your attention to detail. How many techs would bother with demurring holes or removing all the lead wire from a terminal strip? Thanks for sharing.
I don't think the caps sound much different but I do notice with new paper and oil caps, that the sweep on the tone control stays brighter as u turn it down. Then other capacitors. I agree vishey caps are good quality, I use them everything. Never had a failure or problem.
Thanks for yet another great video! Question about the black sprague cap: I have heard that the black spragues with red writing are a difilm construction that rarely leaks or goes bad, but the ones with yellow writing are paper and foil and nearly always leaky. Have you found this to be true?
I love these Gibson amps. Wish they would reissue these. I have 2 and my 60’s amp is missing a power knob. Any tips on where to find a suitable replacement?
Another tech suggested in his video that this amp is very similar to the Princeton…. How do you feel about that? And how could a tech do that? I have this Gibson so I go send it to you if you want to put it on your show
No, enlarged a hole for the power cable retainer. That cable is not against bare metal. The wires passing through the ungrommeted hole are factory and the owner wanted it kept stock as possible.
Hey Lyle, what's the over/under on how many comments you get about keeping/using the transformer mounting hardware as grounds even though this transformer is so light it doesn't make a difference? I wish we could set up a "But you said..." counter!
Technically not up to code though right? Supposed to have a dedicated connection/bolt just for ground? I know it's "technically" fine & will always be fine, but we nitpick here right? Would it be "cool" if this amp came in from another tech like this or would we "need" to change it because we don't use transformer bolts for grounds? I'll be on the lookout for a video of this amp from the next tech with "60's Gibson Skylark amp: Tech tries to kill player & almost burns down the local blues jam". All fun & games & I love your work Lyle. I appreciate these videos & have learned a ton from them.
To think the number of those sprague that I replaced and trash caned and replacing them with high grade polyprop and styrenes in Dynaco preamps ETC . If only one saw that some poorly informed people would pay that much for those I would have save all of them . And bought all of them I passed on NOS surplus . Hype is a wonderful thing if your the seller not so much if your the buyer. For 6aq5 with small output transformer I would suggest that about all you could expect. The lack of low end causes the amp to sound tinny so to speak . Most human are hearing in a relative way so less bass more treble when the treble is the same and bass is way up or down . It this amp it is both an unfriendly treble and low bass output to me .
Great episode! Love the value-added "digressions". :) Original inspection video is here, in case others are intersted: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENaj4A0JWhE.html 👍
