That's cool that it was the same factory tech that looked at both amps. It looks like that amp was also repaired two other times at the Fender factory in 67!
I seen a guy go into a old fender and the first thing he did was cut all the tone caps out it was about 5 years ago and I was thinking why he did that without checking them ,now I know how important they are to the tone of the amp and im sure some one in the comments tore him up for doing that
I’ve got a 67 Bassman like this*. No emblem, brownish grille cloth, better tolex but more little knicks in the black panel. Love it, it sounds amazing but has some 60hz tone on the power tube grids I can’t shake. Manifests as intermodular distortion/ghost tones. Think it’s bias voltage differential between the two tubes being close but not close enough. Just to clarify, I’ve still got all the old blue coupling caps at least.
Maybe you have a little dc leaking from somewhere. If you had dc on the grids, you’d go into thermal runaway, though. If it’s 60hz that’s pre rectifier, so maybe some noisy imbalanced heaters or a lead dress issue? Edit: ghosting is usually associated with failing power supply caps. Forgot to mention.
NICE AMP! I am blessed to own a 1967 Showman in really good condition. Only difference between this and a Twin, is that the Twin has Midrange on both channels. I have gone to installing 5881's in my 6L6 amps ... I don't need so much power and I think the bottom is a little tighter with the 5881's. I am a fan of the new Tung-Sols. And PT is tough stuff. But good on you for wanting to go that route, initially. What's fun, is putting that nut BACK onto that screw behind the power transformer! I use a piece of rolled tape stuck to my finger with the nut stuck to the tape. I am not a tech; but SoZo blue caps for tone and coupling look pretty snappy and sound QUITE nice! And there ARE people who "steal" those Blue Ajax caps and sell them on eBay. And I absolutely agree with you on that "drifting" thing. I am in the slow process of having all my Fenders de-junked inside.
All your comments are solid gold! Spot on, too. There was a time when a dude could find Phillips JAN 6L6WGBs for next to nothing and they’d do such a treat for lowering perceived headroom in the bigger iron Fenders. Now when someone asks me to help bring out some compression and smoothness tweak the screen supply. That nut is what I all the not from hell lol. I have a long socket that I use to position it, but even then you have to use the force and go by feel 😂
@@thatampguy Yessir! I started playing seriously, in 1961 when tubes were really good and just taken for granted ... Western Electric was going to start making real tubes again here in the States ... but I haven't seen a single one come out of Georgia! And neat that this Fender tech made two appearances on your bench! Amazing, what? And historically ... My very first guitar was a 1954 Stratocaster I got for Christmas of 1963 (I had been playing my brother's Jazzmaster, prior.). Glad you enjoy these old Fender amps so much. I am blessed to own a 1964 Super Reverb that I bought NEW in 1964! Thanks for your reply. Very kind of you.
I see this kinda thing almost daily. I got a Blues Deluxe Mk1 that had been clipped and tack soldered with what I assume was non resin core solder and track repair with wire. The owner said he couldn't find a Tech so he gave it to a hobbyist who repairs radios. Poor radios....
I just made a comment on another channel about how old amps have a story to tell. Thats part of the charm of working on them. and keeping the history alive.
Isn't it a fitting tribute to Leo Fender's commitment to quality that everyone just took it for granted that these amps were just indestructible (and so treated them accordingly)?
Not all fenders from the black or silver face families shared identical negative feedback and tone cap values for what it’s worth. Some had .022μf in the tone stack for example.
Generally the jacks are wired in parallel to share the output from the amp. When you connect speakers to both, the amp splits its power between them, and the total impedance seen by the amp changes. The speaker jack must have something plugged in for the extension jack to function properly. On some, using the extension jack only could damage the amp.
That is really cool and what would be even cooler is if Lupe Hand wired it, and her tag was still inside,oh what a shame all the tone caps disappeared ,I guess Lupe wasnt there after CBS bought the company but I was hoping
We do not typically measure that, as transconductance, which we measure in Siemens, is used to express how efficiently a tube (edit: or transistor) converts input voltage to output current. Instead, when biasing, we are setting the operating point of the tube to a range between cutoff and saturation.
@@thatampguy To measure each output tube In-Circuit you measure the DC or AC input voltage at the grid and divided by the plate DC current = Transconductance, isn't this what some tube testers do or the tube testers that measure transconduance is apply an AC sinewave voltage to the Grids and measuring the plate current?
Transconductance is basically a measurement of gain. If you want to see that math, Transconductance is expressed as: Gm = ΔI out / ΔV in ΔI out = the change in output current ΔV in = the change in input voltage Edit: yes that’s what some tube testers essentially do. Apply a sine at the tube’s input then run the numbers.
@@thatampguy I didn't know that the tube testers were applying an AC sinewave form and measuring the output tubes plate current I'm guessing by taking the "average" of the Input voltage low to high RANGE and taking the average transconductance. If you put you oscilloscope Ch#1 at the grid and Ch#2 on the plate it can measure the output tubes voltage GAIN, but how is this different than transconductance?
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That's cool that it was the same factory tech that looked at both amps. It looks like that amp was also repaired two other times at the Fender factory in 67!
Totally possible!
I seen a guy go into a old fender and the first thing he did was cut all the tone caps out it was about 5 years ago and I was thinking why he did that without checking them ,now I know how important they are to the tone of the amp and im sure some one in the comments tore him up for doing that
So cool! (the coincidence and the dual showman)
Mind. Is. Blown. It's like he guided it here to my bench.
I’ve got a 67 Bassman like this*. No emblem, brownish grille cloth, better tolex but more little knicks in the black panel. Love it, it sounds amazing but has some 60hz tone on the power tube grids I can’t shake. Manifests as intermodular distortion/ghost tones. Think it’s bias voltage differential between the two tubes being close but not close enough.
Just to clarify, I’ve still got all the old blue coupling caps at least.
Maybe you have a little dc leaking from somewhere. If you had dc on the grids, you’d go into thermal runaway, though. If it’s 60hz that’s pre rectifier, so maybe some noisy imbalanced heaters or a lead dress issue? Edit: ghosting is usually associated with failing power supply caps. Forgot to mention.
NICE AMP! I am blessed to own a 1967 Showman in really good condition. Only difference between this and a Twin, is that the Twin has Midrange on both channels. I have gone to installing 5881's in my 6L6 amps ... I don't need so much power and I think the bottom is a little tighter with the 5881's. I am a fan of the new Tung-Sols. And PT is tough stuff. But good on you for wanting to go that route, initially. What's fun, is putting that nut BACK onto that screw behind the power transformer! I use a piece of rolled tape stuck to my finger with the nut stuck to the tape. I am not a tech; but SoZo blue caps for tone and coupling look pretty snappy and sound QUITE nice! And there ARE people who "steal" those Blue Ajax caps and sell them on eBay. And I absolutely agree with you on that "drifting" thing. I am in the slow process of having all my Fenders de-junked inside.
All your comments are solid gold! Spot on, too. There was a time when a dude could find Phillips JAN 6L6WGBs for next to nothing and they’d do such a treat for lowering perceived headroom in the bigger iron Fenders. Now when someone asks me to help bring out some compression and smoothness tweak the screen supply. That nut is what I all the not from hell lol. I have a long socket that I use to position it, but even then you have to use the force and go by feel 😂
@@thatampguy Yessir! I started playing seriously, in 1961 when tubes were really good and just taken for granted ... Western Electric was going to start making real tubes again here in the States ... but I haven't seen a single one come out of Georgia! And neat that this Fender tech made two appearances on your bench! Amazing, what? And historically ... My very first guitar was a 1954 Stratocaster I got for Christmas of 1963 (I had been playing my brother's Jazzmaster, prior.). Glad you enjoy these old Fender amps so much. I am blessed to own a 1964 Super Reverb that I bought NEW in 1964! Thanks for your reply. Very kind of you.
@Tonetwisters dude I’d love to have you on the show at some point. You guys are super interesting and had boots in the ground back in the day!
I see this kinda thing almost daily. I got a Blues Deluxe Mk1 that had been clipped and tack soldered with what I assume was non resin core solder and track repair with wire. The owner said he couldn't find a Tech so he gave it to a hobbyist who repairs radios. Poor radios....
😂
I just made a comment on another channel about how old amps have a story to tell. Thats part of the charm of working on them. and keeping the history alive.
Indeed, man. I think it’s a way to honor the old techs too.
Great origin story! Thanks for sharing!
Thanks for suffering through it. Was it like watching a caveman discover fire? 😂
Another casualty of an unscrupulous tech (probably). RIP blue's
…and all the air goes out of the room😢
Isn't it a fitting tribute to Leo Fender's commitment to quality that everyone just took it for granted that these amps were just indestructible (and so treated them accordingly)?
That’s the truth, lol. Leo was a Repairman, so I suppose he didn’t want to see these things coming back in for service. Ha ha.
wrong FB Resistor, should be 820 ohm with 100 ohm to ground. Also Mid Caps in Tone Circuits should be .047
Not all fenders from the black or silver face families shared identical negative feedback and tone cap values for what it’s worth. Some had .022μf in the tone stack for example.
@ from what I know only the Super Reverb had .022 Mid Cap
Ah you mean this specific amp, sorry. Yeah the combos typically had the smaller value if I recall. My brain has been mush the last month or so 😂.
What's the actual difference between the "speaker" and "ext. speaker" outputs? I've only seen the "ext. speaker" output on a combo amp.
Generally the jacks are wired in parallel to share the output from the amp. When you connect speakers to both, the amp splits its power between them, and the total impedance seen by the amp changes. The speaker jack must have something plugged in for the extension jack to function properly. On some, using the extension jack only could damage the amp.
one of my favourite guitarists, Efrim Menuck uses one of these, incredible amp!
I will look him up! Ty for mentioning him.
cool info in here!
Thanks for watching! 🤘🏽
That is really cool and what would be even cooler is if Lupe Hand wired it, and her tag was still inside,oh what a shame all the tone caps disappeared ,I guess Lupe wasnt there after CBS bought the company but I was hoping
Yeah man I don’t think she was around :(. Still a cool project. Man. Unreal.
When biasing the output tubes, how do you measure each of the output tubes transconducance?
We do not typically measure that, as transconductance, which we measure in Siemens, is used to express how efficiently a tube (edit: or transistor) converts input voltage to output current.
Instead, when biasing, we are setting the operating point of the tube to a range between cutoff and saturation.
@@thatampguy To measure each output tube In-Circuit you measure the DC or AC input voltage at the grid and divided by the plate DC current = Transconductance, isn't this what some tube testers do or the tube testers that measure transconduance is apply an AC sinewave voltage to the Grids and measuring the plate current?
Transconductance is basically a measurement of gain. If you want to see that math, Transconductance is expressed as:
Gm = ΔI out / ΔV in
ΔI out = the change in output current
ΔV in = the change in input voltage
Edit: yes that’s what some tube testers essentially do. Apply a sine at the tube’s input then run the numbers.
@@thatampguy I didn't know that the tube testers were applying an AC sinewave form and measuring the output tubes plate current I'm guessing by taking the "average" of the Input voltage low to high RANGE and taking the average transconductance. If you put you oscilloscope Ch#1 at the grid and Ch#2 on the plate it can measure the output tubes voltage GAIN, but how is this different than transconductance?
Transconductance is how effectively it changes or converts the input into the output!
His name was Reginald Carlisle, and you can't tell me any different 🤣
The 3rd! Lol, I was hoping his name was Ronald Cabrini 🤌🏽🤌🏽
@@thatampguy happy to see that your Alnico speaker survived the fall from the backada truck! AAAAAAAyyy
@GetTheLedOut8585 😂lol
Slopa paloza!😅
Sorry 😂I meant to cut that out
Sanctimonious? You ain't
😂
Pontificating? Pontificatious? 🤔