Question for Fender guys

[catalin gramada]

Hallo,
have a question regards power tubes used in Bassman 100 from 70-73 era,please. I just remark this series from those years used a quad RCA power tubes with 2 short bulbs and 2 long bulbs like the pics show. From begining I thought it was a sort of factory mistake but if you look at bassman 100 amps from this era will see is a current factory practice which was assumed from whatever reasons they have. Did someone know from what reasons they used for , please? Thank You.
Best Regards
Catalin





Those pics are from two different amps stock factory powertubes

[loudthud]

A guitar player in one of my bands had one of those amps that he got new back then. IIRC all the 6L6's were the same size. I moded the amp to have an extra gain stage. Added a 12AX7 next to the phase inverter. He played it into a Marshall 4X12 slant that I re-wired to 4 Ohms.

[catalin gramada]

Hi
Yes I know. many of these amps have all 6l6 in same size. Just I wonder what's happening with some from 70' era. A friend of mine wants to buy a 73' one and he saw it have all RCA 6l6 from different size (two by two). We suspect it was replaced or it was a factory mistake in best case.But looking at other bassman 100 from the same era (original power tubes) we saw was not a isolate case, it was a common practice, I wonder what reason they have to use it ?

[Enzo]

It is human to try and see patterns in everything. But Fender did not select different size tubes for some purpose. The tube innards are the same regardless if the glass envelope is taller on some. Fender didn't even match tubes, that is a latter day fetish. If some came from the factory that way, it was luck of the draw pulling tubes out of the bulk boxes of tubes. Perhaps a production line worker found a couple cases of tubes of different size envelopes and out of boredom decided to put taller ones in the center just because he/she could. I'd read nothing more into it that that. It certainly isn't a "mistake".

[catalin gramada]

Hi Enzo
They are the same tubes, for sure, just diferent bulbs. It is just curious how the same pattern was used for some. I thought the same like you till found other amps pics from that era looks identical

[Leo_Gnardo]

Perhaps a production line worker found a couple cases of tubes of different size envelopes and out of boredom decided to put taller ones in the center just because he/she could. I'd read nothing more into it that that. It certainly isn't a "mistake".

^^^ What I was about to write. About that time RCA started using taller bottles, the insides still the same with the four "c" cutouts in the top mica. Later on even that went away & they were still very good tubes, just not the vaunted "black plate."

Then RCA went away and Sylvania "STR" 6L6GC were the norm. Also good tubes. I sometimes find them in old Fenders, still working fine.

[catalin gramada]

So, in consequence looks like a "soft transition" at components supply. Thanks for your answers

[mort]

The way I understand it, Fender didn't waste anything. This is evidenced also by the '64 model "transition" amps when they switched from brown tolex & control panels to the later black tolex and control panels. There are plenty of amps that have black tolex but a brown control panel, or vise versa. They depleted all stock even if it meant not matching and this sounds like the same sort of thing.

[g1]

I would guess that during the transition to the new bottles, they were supplied with both. The line workers were probably told to use pairs or quads, but not 3 & 1 as that would look odd to the consumer.
The actual arrangement when using 2 different pairs was probably at the discretion of the line worker.

[catalin gramada]

I would guess that during the transition to the new bottles, they were supplied with both. The line workers were probably told to use pairs or quads, but not 3 & 1 as that would look odd to the consumer.
The actual arrangement when using 2 different pairs was probably at the discretion of the line worker.

It is a best probable scenario

[Enzo]

I dunno, that sounds like a rationalization to me. After all, if they still had supplies of both sizes, then it would not be necessary to mix them. Just put all four of the same size into each amp. Some might be taller than others, but you only notice that comparing amp to amp. No one does that. So if you have boxes of tall ones and boxes of short ones, no need to reach into two boxes. Just pick one and install four tubes from it. If we come down to the end of the boxes of tubes, we might have ONE amp needing the mix. because if you have enough tubes of each type to do TWO amps evenly with both sizes, then you have enough tubes to do two amps with all the same in each.

REmember, this is a production line environment. Your tubes came in boxes of 100 or whatever.

[catalin gramada]

I.m not a Fender defender but just can to suppose if they was at the end of stock and still needs to do pairs or quads it is more difficult to choose from a limited stock. Mixing with new ones they still have a chance to use all tubes from old stock they had. Just my supposition....

[Enzo]

But why not just use the old stock period? if you have enough amps in production to use them up. What woul dbe the point of mixing in newer ones just to make using up the older ones take longer?

If you have a half carton of eggs in your cooler, and buy a new dozen of eggs, would you mix in new eggs with the old for your omelet to use up the old? or would you just finish the old ones first?

We are thinking up convoluted reasons for something that Fender wouldn't care in the slightest about.

[52 Bill]

We are thinking up convoluted reasons for something that Fender wouldn't care in the slightest about.

And why not only use short bottles in amps with only 2 6L6s?

It was probably a bored line worker that liked to add his or her "signature" to the amps. At least until some supervisor caught it or they got bored with doing it.

[g1]

My theory on that was based on the (probably mistaken) idea that the tube supplier was supplying cartons of tubes with both size bottles in them. At least during their bottle size transition period. After all, they are the "same" tubes.