Best 25" tube chassis color rectangular set of all time? - Videokarma.org TV - Video

maxhifi · #1 09-11-2019, 09:27 AM

I have limited experience as a collector, and I'm curious if there is any consensus among people who have been around more TVs than I have.

My impression is that Zeniths are better quality, but RCA has a better picture, particularly in terms of better color. The only RCA tube chassis I have is a CTC38, and it produces a beautiful picture. Solid red on the RCA tends ever so slightly toward magenta, but skin tone is perfect, and green looks fantastic.

On the other hand, my Zenith has a slightly sharper picture, with better defined scan lines, but the color just isn't great like the RCA. No matter what I do, green is slightly dull, and skin tone never looks completely real. The RCA has almost no buzz in the audio, where the Zenith always does on bright graphics.

If a person wanted to find the absolute best 25" rectangular screen tube chassis TV chassis ever made, from the perspective of picture and sound quality, where should he look?

Is it the RCA CTC17? Is it a Zenith? Is it something else?

Electronic M · #2 09-11-2019, 10:54 AM

IIRC 25" viewable came out around 1970...By that time most makers were tube/SS hybrid. Probably the only all tube rectangular sets were 23" viewable.

IDK if they sold the 20BC50/20CC50 with 25" tubes, I have a 23" CC though, but those have very good color and all the sharpness of the higher semiconductor count (read higher end) chassis of their day...they preform on par with the flatchass CCII sets Zenith rolled out around that time.

maxhifi · #3 09-11-2019, 11:01 AM

I should clarify by saying 25" nominal, or 23" viewable - like the 25XP22, or etc.

I mean TVs of the 1966 - 1970 era, more or less.

Popester · #4 09-11-2019, 08:15 PM

I guess I would favor the zenith line slightly. It's all a matter of personal preference. I favor Zenith mainly from a quality stand point. They had less flyback failures. RCA always seemed to have issues with flyback failures. Maybe because of the donut design that they used. As for picture quality. I think Zenith and RCA were really neck and neck about the same. As for me my favorite was when Sony came out with the 26" line. Favorite delta tube set would be the CCII black matrix picture.

trinescope · #5 09-11-2019, 08:31 PM

The best 25 (23V) 1960s set I ever saw operating was an RCA CTC40. I put a used 25XP22 in it to replace the tired Colorama rebuilt 25BCP22 that was in it and was blown away with the clarity and color from that set. Of the tube type sets from that era IMO the RCAs gave the best picture, but had to have the small signal tubes in top shape for that. Zenith was a VERY close second and normally more reliable. Motorola tube sets had weird color reproduction, probably from that jack of all trades, master of none 6LE8 demodulator with the G-Y output taken from a screen grid. Silvertone color sets just never looked good to me. The Motorola TS-915 was decent but not as good as the CTC-40. The GE KC I had was really good as well, that one used separate diode demodulators for the three color difference signals.

maxhifi · #6 09-11-2019, 09:53 PM

I have a TS-915, albeit with a weak tube, and the color isnt even close to my CTC38. The detail and geometry are better, but color is really important. That said, the ctc38 improved substantially when I changed a bunch of 6GH8s. It surprised me how hot they get, I suspect the tv runs them hard.

I'm going to have to read about the ctc40, I don't remember seeing one in person.

Electronic M · #7 09-12-2019, 08:57 AM

I'd probably vote Setchel Carlson followed by Zenith...In the roundy era RCA sent engineers to SC to try and figure out how SC was getting a better picture out of RCA made roundy color CRTs than RCA themselves were. SC also has the advantages of being a 100% hand wired MODULAR chassis where you could do neat things like pull the color module and have it continues to operate as a monochrome set. Circuits were a mix of RCA based stages and their own designs.

It is funny some folks think Sivertone was worse than RCA... most Silvertone color sets were RCA clones the early ones were nut and bolt clones, and as time progressed they started customizing chassis metal board placement and component placement... granted they probably were not using the latest RCA circuits at any given time...so a new RCA that out performed older RCAs probably looked good next to a new Silvertone some years.

trinescope · #8 09-12-2019, 10:17 AM

Quote:

Originally Posted by Electronic M

I'd probably vote Setchel Carlson followed by Zenith...In the roundy era RCA sent engineers to SC to try and figure out how SC was getting a better picture out of RCA made roundy color CRTs than RCA themselves were. SC also has the advantages of being a 100% hand wired MODULAR chassis where you could do neat things like pull the color module and have it continues to operate as a monochrome set. Circuits were a mix of RCA based stages and their own designs.

It is funny some folks think Sivertone was worse than RCA... most Silvertone color sets were RCA clones the early ones were nut and bolt clones, and as time progressed they started customizing chassis metal board placement and component placement... granted they probably were not using the latest RCA circuits at any given time...so a new RCA that out performed older RCAs probably looked good next to a new Silvertone some years.

Never seen a Setchell Carlson set myself, so I know nothing about them. The Silvertones, maybe the ones I had were tired and full of bad tubes, but they all had the same "soft" picture quality to them. These were not the straight ahead RCA clones, but the late 60s models. I would like to find one of these now and see just how good I can get one to work with the knowledge and equipment I have now versus back in the 80s as an early teenager who could only do tube replacement and simple troubleshooting. I'm hoping it will change my earlier first impressions of this brand.

I do have a Sears Medalist II 19" hybrid here now that shows a lot of promise for being a great performer. It just needs a bit of tweaking to get to 100%. It has a nice Sylvania black matrix CRT in it with a red that looks really close to 15GP22 red. But that set is from 1973 and probably was designed better than the earlier ones. The PC boards are actually really nice with silk screening on both sides, so it's easy to figure out how everything is connected, and all the module pins are labeled as to their function.

maxhifi · #9 09-12-2019, 10:36 AM

The roundie Silvertone set I had, but sold, had two different tint controls, as does my Motorola TS-915. Both of these sets are very cumbersome to adjust to get the tint set right, and it always seems a little off to me. I could adjust them to look good with one source, and then change the channel and it would look off a bit.

The single tint control on the RCA and Zenith sets seems a bit more evolved to me.

I dug out my RCA service info for 1969-1970, and was going through the CTC40 circuit last night. This looks like a really neat set - basically a drop in solid state replacement chassis for the CTC38. If anyone viewing this needs factory schematics for any of the 1969 RCA sets, I can scan some of the info.

How does 15GP22 red differ from 25XP22 red? I noticed on the 25XP22, that red isn't a deep red, but more of a bright red. It is slightly different from what a modern TV would produce, but not in an offensive way. This is noticable with things like the CNN logo, for example. It's actually my only complaint about the colour on the CTC38.

trinescope · #10 09-12-2019, 11:23 AM

25XP22 had the rare earth red phosphor which was less orangey than the sulfide red used in the earlier tubes since the 21CYP22. The 15GP22 red is more of a deep blood red color but not very efficient. The big deal about it was that particular red color got enshrined as the "correct" red in the NTSC specs along with the green and blue as well. Later tubes got the red color closer to the original NTSC spec again.

I remember the first time I ran across the sulfide red was in a Zenith 23XC38 with a 25AP22 tube. The reds were more orange than what I was used to seeing from my parents' 25CC50 Zenith and later inline RCA sets.

bgadow · #11 09-18-2019, 08:48 PM

I've seen a very pleasant picture from a Sylvania and even a DuMont (Emerson) from that era, and I had a Philco that really impressed me. But an RCA, if in good working order, is a notch above. The Zeniths I've had from that period didn't quite match an RCA in color but they ALWAYS beat them in reliability.

freakaftr8 · #12 09-18-2019, 10:11 PM

When an RCA is finely tuned and properly set up, I have to say RCA hands down. I don't know what it is about them, especially my CTC-39, which has the best picture I've ever seen on a tube set, the picture quality is top notch with excellent DC restoration and razor sharp focus and excellent convergence. Even my old CTC-16 that Chrisw6ATV got from me a few years back had an amazing picture after I rebuilt half the damn chassis. An out of sync RCA thou, looks like some of the worst. Now I have seen great pictures come out of Chromacolor sets, I just have not seen any "jump out of my seat" video output being produced by anything Zenith pre chromacolor. Imho, zenith has always had issues with DC restoration, way too much contrast and adversely affects greyscale when there is a bright image on the screen that also requires black level content, and that audio buzz... drives me nuts.. Magnavox is blah and has a muddy soft picture. Silvertone and wards airline sets too. That's about all I have owned.

trinescope · #13 09-19-2019, 11:53 AM

I forgot about Sylvania... the only one I had (hybrid chassis) when it worked was at least the equal of a Chromacolor for picture quality.

The Motorola TS-918 I have now is working pretty well for what it is and looks about Zenith picture quality except for the weird flash tones that always seem off no matter what the hue control is set at. I need to find a vectorscope and investigate. The demodulator angle looks to be fixed by non adjustable components.

I have a basket case Zenith 20X1C38 that I need to get working and do a comparison with the Motorola. Both are 21" tabletop sets. The Zenith has a few difficult fixes needed like replacing the HV rectifier filament winding that was cut off and a solid state diode (that had failed) installed, two adjustable coil forms in the convergence assembly fell apart, and two pins on the CRT pulled out and stayed in the socket. I did get a raster for a brief time so the CRT is still under vacuum. Maybe defogger grid conductive epoxy can fix this.

consoleguy67 · #14 09-19-2019, 01:25 PM

You say that Magnavox sets had muddy pictures? I had a 1964 roundie set that was outstanding. My parents had a 19" table model that had one of the clearest, and accurate color pictures. The biggest problem with Magnavox was that after Phillips bought them, the reliability wasn't there anymore.

sampson159 · #15 09-20-2019, 10:22 AM

the zenith flat chassis was the best set.they were built like tanks with the famous zenith black matix crt.sylvania hybrid sets especially the d16 with slide controls were very close as where the early xl100 sets.philco produced some great sets as well.i have a magnavox bicentennial set that might have the best picture in my collection.its really a matter of taste.the best picture i saw was a tossup between the first color set which was a ctc 100,first zenith color and a zenith hybrid that had a picture that rocked the house!i like the sylvania dark matrix crt but had a short life.vdc rebuilt a few that lasted many years.i have one in a e45 set.also saw a setchell carlson that had an unbelievable picture.the only sc color set we ever got in.