Sunn logos through the years...

[Rex B]

Here's my best guess for some of the logo questions. Sundholm owned Sunn: Smiley faces and Silver on black, either anodized or silkscreened. Harzell owned Sunn: White Sunn, Red 0))  either screened on metal, later plastic. The yellow/orange on metal is most likely fading (sunlight etc)  probably from switching  screen ink formulas to something less toxic because screeners were getting goofy on fumes. It was always kinda like happy hour in the silkscreen dept. Late Hartzell, (1984-ish) serif logo. The serif logo tends to go with the Bennett miter-fold cabinets, with the plastic edge molding and plastic laminate instead of tolex. (Bennett was in Troutdale OR, cabinets were built there after Sunn closed the Williamstown KY plant, a cost-cutting measure)  Fender owned Sunn: Back to the White Sunn, Red 0)), plastic logo. There was always some overlap / mixing because logo plates were bought by the thousands, and chassis were made in relatively small quantities. 

[Rex B]

Fender / Sunn logo's, crossbranding.

I think the serif logo was incorporated around 1984 as a "new look" with the Bennett miter-fold cabinets (plastic edge trim). Sunn was struggling, they were cutting costs and corners, and Jim and Tom Hartzell were getting disillusioned. This lasted until Fender bought Sunn in 1985.

To the best of my knowledge, other than building out and selling existing Sunn stock, Fender never built the miter-fold cabinets or used the serif logo. They didn't need to: John Cherry was building great cabinets in S Cal, and Ensenada was firing up with good cabinets too.  By the time Fender bought Sunn, there really wasn't much left to buy, other than Tote Box powered mixers and lighting, which were both actually doing fairly well, with good profit margins.  Fender's main interest in Sunn was to have a manufacturing facility to bring manufacturing back to the USA from Japan.

There were many Fender products that got Sunn logos put on them because this allowed Fender to sell thru both Fender and Sunn distribution channels, primarily overseas. There were Twins, Champs, Deluxes etc dressed in Sunn clothing, with different model names, and likewise, Sunn products dressed in Fender clothing (mixers etc). Same guts. Fender was doing VERY well, and could barely grow fast enough to build the new red knob Fender stuff, much less any slow-selling Sunn stuff. Sunn got lost in the shuffle. There was no slapping the Sunn logo on inferior stuff that I know of, at least not in Lake Oswego.

[EdBass]

I think the switch from the smiley face to this logo (sans the "R") was made in 1966;

That was fairly early in the Sundholm era, and I believe Hartzell used it as is for a year or so, before adding the red graphic in the mid-late 70's.

On a side note; I personally think the serif logo is butt ugly!

[CLD]

Conrad sold the company to Hartzell some time in 1971, so they stuck with that style at least through 1975 (the last catalog I have from that era).