Anyone know what type of caps Fender used AFTER the Chocolate Drops in 70's SF's?

[BrownsBrick]

I came across some caps I thought were Mallory PVC's in my Deluxe Reverb, only to find they were the original mid coupling caps (.47). They are blue drops, slightly misshaped with silverish/white lettering.

Worth keeping/replacing? Did Fender ever change from Chocolate Drops to Blue Drops? I'm feeling my amp a tad sterile and these might be part of the culprit. Sozo just came out with they're copy of the original Blue Atoms in .33, I may check these out or just stick with Mallory 150's.

Thanks and much appreciation,
BB

[muchxs]

I use "plain" Sprague orange drops in most of my stuff. It's not so much about magic parts as using the right parts in the right place.

[BrownsBrick]

Originally Posted by muchxs

I use "plain" Sprague orange drops in most of my stuff. It's not so much about magic parts as using the right parts in the right place.

I agree. Since I just started getting into working on amps I've come to the conclusion that all this fancy mojo/carbon comp resistor/lead dress stuff doesnt make too much of a real difference anyways. I did a sloppy job of building my first amp, then went back and redid everything, only to find it sounded exactly the same as it did before just more pic friendly. I guess just more or less interested in these post-chocolate drop caps, doesnt seem to be much info on them.

[muchxs]

Just a thought but the late Deluxe uses a 5U4G rectifier which is harder than the hinges of Hell. I like the 5AR4 used in the earlier Deluxe, I don't like the higher voltage I get when I swap a 5AR4 for a 5U4G. Just me but I'd mess with that and see if there isn't a little mojo there. Bear in mind that when you change your supply voltage you may want to fiddle with your PA bias point. Don't worry about it, don't obsess over it, just be aware that it's something to think about.

[BrownsBrick]

Originally Posted by muchxs

Just a thought but the late Deluxe uses a 5U4G rectifier which is harder than the hinges of Hell. I like the 5AR4 used in the earlier Deluxe, I don't like the higher voltage I get when I swap a 5AR4 for a 5U4G. Just me but I'd mess with that and see if there isn't a little mojo there. Bear in mind that when you change your supply voltage you may want to fiddle with your PA bias point. Don't worry about it, don't obsess over it, just be aware that it's something to think about.

The voltage from the wall in my area is already a whopping 125, I WISH I could use a 5ar4, but I have a feeling that could kill even JJ's in my amp. BUT funny enough, I checked the bias and the JAN Sylvania's were running at 10ma with 465 volts on the plate. Weird thing is, I biased the thing just about a month ago at 20ma and havnt used it since (stupid drummer lost the practice space keys). Biased it back up to 20ma and it made a world of difference.

maybe someone else was putting some work on it...:?

[Wally]

Brownsbrick, if those were new tubes they may have 'burned in' after the first hours of hot use???? I would keep an eye on the bias just to know how stable those tubes are.
20ma at what voltage??? For my purposes, I would bias that thing as warm as I could stand it just to bring the voltage down. You may have it about as hot as it can go, though. 20ma at 460V = 65.7% of max plate dissipation. OF course, that voltage is just a guess for the equation, right?

[muchxs]

Originally Posted by BrownsBrick

I checked the bias and the JAN Sylvania's were running at 10ma with 465 volts on the plate.

Originally Posted by Wally

You may have it about as hot as it can go, though. 20ma at 460V = 65.7% of max plate dissipation.

Originally Posted by BrownsBrick

Biased it back up to 20ma and it made a world of difference.

I know you love your FACS, Wally but this thing is a poor man's Kelley at that kind of voltage. It's no wonder it sounds a little "stiff". I think the high plate voltage in Deluxe Reverbs is a design flaw. They sound better when correctly biased but they'd sound better still IMO with less than 400v on the plates.

[ThermionicScott]

I don't agree with biasing the tubes hotter just to get the plate voltage under a certain number. If the tubes are going to arc at a particular voltage, they'll arc when the plate voltage swings up during a signal, I would think.

Just for fun, I threw some old GE 6V6's in my 5E7 and because they are tired tubes that didn't sip much current, the plate voltage went up to 470V or so. I cranked up the amp and played some loud stuff and nothing bad happened. Now, maybe they were fine because they used the later glass disc mounting rather than the earlier pinch base, but my point is that voltage isn't the main concern as long as you're using decent tubes.

I don't have a DR to try this on, but does anyone know what the B+ sags to under maximum signal? For all I know, Leo Fender was actually following RCA's advice that the plate voltage could be 350V at maximum signal, and that the screens could be as high as the plates as long as their dissipation was in check.

On a slightly-related note: I found it neat that when I had an o-scope and a signal generator hooked up to my 5E7 clone (which has idle voltages very close to the schematic), the plate voltage sagged to almost exactly 360V at max signal, and was putting out the rated 26W into a dummy load.

- Scott

[celeste]

Originally Posted by muchxs

I use "plain" Sprague orange drops in most of my stuff. It's not so much about magic parts as using the right parts in the right place.

Ahhh, but which Orange Drop, there are so many, 715 716 225 418..........


LOL, as they say the devil is in the details and it is devilish to give only part of the story.

[Wally]

Hmmmm...muchxs, instead of championing that high voltage, it seems I was trying to think of a way...any way... to bring that plate voltage down...increasing the current draw will do that to some small extent. And I am sure that the 465V decreased some bit when the draw went from 10ma to 20ma. I should have suggested a VAriac. This is the best way of maintaining consistent voltages that are simular to the voltages in use when these vintage amps were used. 100-117VAC will put that DR in a different mood.
AS for LEo's design errors, would that I could build an amp that would be so
much-desired in the marketplace 3,4,5 or 6 decades on. OR....that so many folks would be copying those decades later.
As I understand it...limited in my own way....many of these 6V6 and EL-84 amps really don't have much right to function very long at all....but they do. Engineers sometimes have to admit that reality can show theory the path to success. PErhaps Celeste can shed some light on how these amps that apply voltages much above the recommended limits can manage to function and not burn tubes down in a matter of minutes?
Also, can anyone explain to me how, given otherwise equal physical attributes, a redheaded woman is so much hotter looking than a blonde? I have my thoughts...but some other viewpoints might help my understanding on that subject, too. (;^)

[celeste]

Wally, I have to say, it really depends on the redhead or blond, and once she smiles and starts talking, all bets are off.

Oh yeah, the tube thing, you distracted me there for a moment.

I believe that a lot of the tube life above max specs thing is about what tubes were expected to do and how they were rated. Tubes were expected to be relieable at for years and years. When I look at the 10 and 20,000 hour tubes, most of the differences I see between them and their standard breathern are in the filiment, not the plate or cathode or grids. To me that seems to say that in a standard tube operated close to max spec, the weak link is the filiment, so as long as you stay below arc voltage and the heat under control so as not to distort the structor, the tube well may last 2000 hours of the filiment rating.

In other words they are just over built and under spec'ed in the first place. RCA, Syk, KenRad, TunSol et al, even GE (ick) took great pride in their products and tryed to make sure every one met customer expectition.

The whole "modern mains voltage" thing is such a can of worms for people trying to clone vintage amps, or use the real thing. The antiphase bucking transformer on the primary of the PT seems like the best way to go if your PT has old standard primary. I know they make nice dainty Variacs but mine is a 3 phase 30amp unit that is such a pain in the back, hands, arms, the whole body really, to use that I just do not think good things when someone says "Use a variac"

[Wally]

Thanks, Celeste. IME, our society has put up such a 'model' of what a blonde is that many of them do not put forth the effort. They think it should all come to them..they are cold and distant. The redheads, on the other hand, are rare and they know it. They have a self-confidence that simply exudes heat, and they bring their presence forward.
So, how do you increase the current draw in a blonde? Oh, I'm sorry...tubes.....again....LOL

YEp, my old Variac weighs as much as some small amps. I completely understand. It sure does bring those old amps into line, though, and makes the WEstern Electric circuit designs seem more in line with tube design. Good thing they overdeisnged the tubes and underhyped the specs, though.