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Scott
Mono: 310, 314, 330 (schematic), 330C (schematic and alignment guide), 350, LT-10 (schematic, instruction book)
Stereo: 310E (service bulletin and schematic), 333A (schematic), 335, 350B (schematic), 350C (schematic), 370-B (service bulletin and schematic), 4310, LT-110 (schematic), LT-111

Scott's tube tuners were almost all the 3XX series, with popular models like the 310A/B/C/D/E and 350A/B/C. The exception was their kits, which had LT in the model number - like LT-10, LT-110 and LT-111. The LT-111 was the kit version of the 370. For more information on Scott tuners, Lee Shuster's H.H. Scott website and John Byrns's site are 'must-reads.' Here's something to make you say 'wow': A Scott 4310 sold for $2,582 on eBay in 5/05.

Our panelist Bob rebuilt a Scott 335 and came to like it. 'I have it hooked to the H detector output on the Kenwood 600T. It needs a LOT of caps replaced to sound good - there are 5 ceramics and 3 old mylar in the signal path that have to go because they make it sound horrible stock. But after repacing caps, and a few other things, and a good alignment, it is a really nice sounding unit for perhaps the best of everything. One hangup, though, is that it absolutely NEEDS to be aligned to a particular tuner - the separation adjustment is a function of the incoming 19 kHz pilot level, so you need to know the tuner output level, or better, have the tuner on hand, to do the best alignment. Those that like tubes may want to grab one when convenient.'

Our contributor Larry has one of the Scott 350 series tuners, 'a stereo unit with excellent soundstage and tonality. Cap upgrades and tube choices really make a difference here - I used Angela Audio foil in oil caps for the signal path, and primo NOS tubes all around. The 350 sounds better than the Marantz 2130 to me.'

John Byrns comments, 'The Scott 310E uses the same RF, IF, and detector circuits as the 4310, but uses a completely different FM stereo multiplex decoder of a later more refined design than the one used in the 4310. The different multiplex decoder designs may affect the relative sonics of the two tuners. The 310E multiplex decoder was the pinnacle of Scott multiplex decoder design, and later Scott tube tuners and receivers used multiplex circuits that were cost optimized.'

John also describes the differences among the various models of 350 and 350x: 'The original 350 was based on the monophonic 314 which had a cascode RF stage using a dual triode tube, a triode local oscillator and a pentode mixer, with two pentode IF stages and a pentode limiter driving a wide band ratio detector. There was a large open space on the 314 chassis intended for a multiplex decoder module, and the 350 was essentially a 311 with the 4-tube multiplex sub-chassis from the 335 multiplex decoder bolted into the open space on the 314 chassis. The limiter was also changed from the pentode limiter of the 314 to a 6BN6 gated beam limiter in the 350, and additional shielding was added around the IF stages. The 314's tuning eye tube was also replaced with a tuning meter in the 350.

'The 6BN6 gated beam limiter used in the 350 was dropped in the 350B which went back to the original pentode limiter. The 350B also used a higher gm 1st IF tube, although some 350Bs may have also been built with the old standby 6AU6 1st IF tube. The 4-tube multiplex decoder module was replaced with a virtually identical 3-tube design that moved the audio output tube to the main tuner chassis. I assume this change in the multiplex module was made to facilitate its use in receivers where the audio stage would have been redundant. The 3-tube multiplex module differed from the 4-tube module in two ways in addition to the deletion of the audio stage. First, it added switching and some capacitors to create the 'Sonic Monitor' which was Scott's system for identifying stereo broadcasts. Second, the L/C ratio of at least one of the 19/38 kHz tank circuits was changed, presumably to improve the 38 kHz subcarrier recovery.

'The 350C was much like the 350B, but got the new Scott cosmetics, and the limiter was changed to a 6U8 based dual limiter with a diode limiter followed by a pentode limiter. The multiplex module was as in the 350B. Allied radio sold a special version of the 350C with 350B cosmetics, and labeled as a 350B, although it had the new 350C limiter circuit. The 350D dropped the traditional Scott circular dial, which seemed to be a turnoff for many people, and replaced it with a standard slide rule dial to be more competitive in the market. The 350D also used a new simplified multiplex decoder module with automatic stereo/mono switching. The 350D was the only tuner in the 350 series to offer automatic stereo/mono switching.'

Here's John again (perhaps we need to give him his own page?): 'The LT-10 is essentially a kit version of the 314, the only two differences I know of being that the tuning 'eye' tube in the 314 was replaced by a tuning meter in the LT-10, and the original LT-10 had a brown painted face plate while the 314 had the brushed gold color. The [stereo] LT-110B was much like a kit version of the 350B. There were two circuit variations of the LT-110, the main difference being the multiplex subchassis and 'Sonic Monitor' circuit, as in the 350 vs. 350B. The IF/limiter stages of the LT-110B were unlike those of either the 350 or 350B, using three 6AU6 pentodes, the final one as the limiter, as in the original 311. I can't remember if the 'B' designation on the LT-110B refers to the circuit change, or if it only designates the later change to the new styling. Also I forgot to mention that the original 350 used a tube rectifier while the 350B, and later models used a solid state rectifier, IIRC the original LT-110 also used a tube rectifier and the LT-110 with the revised circuit and the LT-110B used solid state rectifiers.

'As far as performance differences between the LT-110 and the 350-D, I haven't had any personal experience with the 350-D, but I would expect that the difference was insignificant as far as RF performance goes. I could never tell the difference performance-wise between the LT-10 and the 310-D even though the 310-D had an extra IF filter and two more tubes in the IF/limiter stages. Theory says the 310-D should have a little more selectivity, but the LT-10 was equally sensitive in my experience. The 310-D did have some extra bells and whistles, though, including a squelch circuit. There could be a difference in the sound quality of the LT-110 vs. the 350-D due to the considerable differences in the multiplex circuits the two tuners use, but as I said I have no experience with the 350-D so I don't know one way or the other. I do prefer the sound of the multiplex circuit in the 310-E to that of the 350(B,C), but the 310-E multiplex is a more sophisticated multiplex decoder design than either the 350(B,C) or the 350-D design. My ideal Scott tuner would be an LT-10 with the 310-E multiplex circuit in it. The 350-D seems to be a somewhat rare tuner, I assume because the 312 came out about the same time as the 350-D, so why would anyone buy an old technology tuner like the 350-D when they could have a nice modern transistorized 312, unless saving a few dollars was important.'