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HH Scott Solid State

R

rmp

Active Member
Several writers have commented that HH Scott quality started to go down in the mid sixties, about the time of the switch over to solid state. I don't think that's true, at least as far as the tuners go. In fact, the quality and innovation continue through to the initiation of bankruptcy proceedings in November of 1972 by the original company, HH Scott Inc of Maynard, Mass. HH Scott himself retired in 1973.

I think the following list includes all the SS tuner offerings during that period. Dates are approximate. Model changes generally reflected external feature changes. Technical changes sometimes led or lagged the model changes.

1964 – 312, LT-112 (kit), and 4312. Nuvistor front end, transistorized remainder. All hard wired.

1965 – 312B. 3-FET front end. Printed Wiring Boards. 315 (budget).

1966 – 312C. Cosmetic changes. LT-112B.

1967 – 312D. Integrated circuit IF section. L/R phones output level.

1968 – 312D (late) LT-112B-1. Ceramic (crystal) filters in IF. 315B.

1971 – 431 AM/FM. LC filters in IF.

1971 – 433 Digital. Nixie tubes and punch tuning cards.

Cosmetics aside, these tuners continue to perform and compare quite well. Interestingly, Scott stayed with a 3-gang front end for the whole analog era.
 
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The 390R was made around 1978 by HH Scott Electronics in Woburn. It's essentially a different company.
 
Recently got a 312C off ebay. Since I already had the virtually identical LT-112B, I almost didn't look at the ad. Fortunately, the seller had taken a photo without the cover, and I saw integrated circuits in the IF strip. It's a stealth 312D. People pay extra for the 312D because of its reputation and because of the L/R phones output controls. As a plus, this unit came with a wood case. It's more appropriate for Scott's tubed equipment and easily sold.

After renovation, the unit's performance is superb, although the muting is flaky. Being analog, it's a pleasure to use.

Scott's combination of a 3-FET, 1-NPN front end and a 4-IC IF set a high bar.

A stealth 348B receiver also recently sold as a plain 348.
 
I want to make some minor additions and corrections to the above info.

The 312 had at least one running change, when the IF strip was moved from alongside the front end to a right angle from it. The MPX section had 5 transistors and 3 transformers.

The 312B added a second function, tuning, to the strength meter. It also re-positioned the rear volume controls to the chassis top. Nuvistors continued through most, or all, of this model. PWBs were incorporated quite early. The LT-112 corresponds to the 312B and had a tri-function meter including alignment.

The 312C and LT-112B added multipath function to the meter, scope outputs, muting, enclosed rear, and FET front end. Integrated circuits were a running change to the IF late in this model. The MPX section had 7 transistors and 2 transformers.

The 312D added L/R phone output level, low impedance rear output, accessory output, 300/75 ohm antenna input, and detachable power cord. The ceramic filter running change to the IF (denoted -1) is reported to lessen sensitivity. The MPX changed again, but I have no detail.
 
As someone mentioned earlier, the 312D (originally circa 1968) had a fairly significant revision somewhere along its production run. The original IF strip with four uA703 opamps and four conventional IF transformers was replaced with a different IF strip with only three opamps and two unadjustable crystal filters. I have been a HUGE fan of the earlier 312D with the IF transformers since I bought mine 48 years ago. As has also been mentioned, this model was virtually the identical circuit to that used in the 348B receiver. I have both versions of the 312D and have aligned them both myself for optimum operation. The early version with the IF transformers is noticeably better in BOTH sensitivity and selectivity than the newer version with the crystal filters. The early one, call it the 312D-1 is the one you want. And I've serviced a 348B and can confirm that it performs just as well as the 312D-1 tuner with respect to its sensitivity and selectivity.

The H.H. Scott 312D-1 when properly aligned is really a remarkable machine. It's the best tuner that Scott ever made, and it remains a top performer today. I have owned and serviced quite a number of tuners, old and new, and while some of them are near matches to the 312D-1, I can't think of one that really works better. The sensitivity and selectivity make it a great DX tuner. The IF bandwidth I've measured at about 230kHz at the 6dB down points which makes it remarkably selective for a single-bandwidth design. The newer 312D-2 I've measured at 260kHz, so it's just slightly less selective than the earlier version.

By comparison, the excellent MacIntosh MR-77 and MR-78 have narrower IF bands at about 150kHz, but they don't actually perform any better in real world reception tests than the 312D-1. The newer tuners with selectible IF bandwidths tend to have them ALL too wide for good selectivity. The Kenwood 600T, for example, is a great design and works very well, but its three bandwidths can best be described as "wide", "wider", and "widest". I've measured the 600T in "wide" mode at 360kHz and in the "narrow" mode at 260kHz. So it doesn't beat out the Scott D-1 for selectivity. And that's the way it performs when you listen to it hooked up to an antenna. If you get a chance to snag a 312D-1, go for it. Get it aligned and I think you'll like it a lot.
 
SEL100 said:
As someone mentioned earlier, the 312D (originally circa 1968) had a fairly significant revision somewhere along its production run. The original IF strip with four uA703 opamps and four conventional IF transformers was replaced with a different IF strip with only three opamps and two unadjustable crystal filters. I have been a HUGE fan of the earlier 312D with the IF transformers since I bought mine 48 years ago. As has also been mentioned, this model was virtually the identical circuit to that used in the 348B receiver. I have both versions of the 312D and have aligned them both myself for optimum operation. The early version with the IF transformers is noticeably better in BOTH sensitivity and selectivity than the newer version with the crystal filters. The early one, call it the 312D-1 is the one you want. And I've serviced a 348B and can confirm that it performs just as well as the 312D-1 tuner with respect to its sensitivity and selectivity.

The H.H. Scott 312D-1 when properly aligned is really a remarkable machine. It's the best tuner that Scott ever made, and it remains a top performer today. I have owned and serviced quite a number of tuners, old and new, and while some of them are near matches to the 312D-1, I can't think of one that really works better. The sensitivity and selectivity make it a great DX tuner. The IF bandwidth I've measured at about 230kHz at the 6dB down points which makes it remarkably selective for a single-bandwidth design. The newer 312D-2 I've measured at 260kHz, so it's just slightly less selective than the earlier version.

By comparison, the excellent MacIntosh MR-77 and MR-78 have narrower IF bands at about 150kHz, but they don't actually perform any better in real world reception tests than the 312D-1. The newer tuners with selectible IF bandwidths tend to have them ALL too wide for good selectivity. The Kenwood 600T, for example, is a great design and works very well, but its three bandwidths can best be described as "wide", "wider", and "widest". I've measured the 600T in "wide" mode at 360kHz and in the "narrow" mode at 260kHz. So it doesn't beat out the Scott D-1 for selectivity. And that's the way it performs when you listen to it hooked up to an antenna. If you get a chance to snag a 312D-1, go for it. Get it aligned and I think you'll like it a lot.
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A major question for you. Do you have manuals? If so, are you willing to scan them? I need manuals. The 312D-1 is a gem, I regard it as the best tuner Scott ever built, and it beats McIntosh in RF prowess in tuners, and matches them on audio quality. My example is cherished.
 
Yes, I have the factory publication for the early 312D-1. Scott published only what they called a "service bulletin" for this model rather than a full service manual. The bulletin contains only the circuit board layouts and the sketchmatics for the early 312D-1. I call it the D-1 to distinguish it from the later version with the crystal filters which I call the 312D-2. Scott made NO model distinction between these two on the front panel or on the serial number tags. So you can't tell one from the other without looking inside at the IF strip. I have not seen any Scott bulletin or manual for the D-2. Which is kind of inconvenient because the D-2 uses a different opamp in the IF strip from the uA703s that were used in the D-1. I have no idea what the newer opamp is. If anyone knows what this chip is, please advise. The one in my D-2 has a Scott part number on it rather than a standard JEDEC type number. I can scan and upload the D-1 service bulletin if you need it. But the 348B complete service manual which includes the alignment procedure for the tuner is available from hifiengine.com. You have to join the group but then you can download any of the manuals for free. I recommend it as a good source for service manuals.
 
Based on the deep reservoir of knowledge here. I purchased a mint LT-112B Thats in for a complete overhaul/upgrade. Eagerly awaiting a listening comparison with the TU9900.
 
SEL100 said:
Yes, I have the factory publication for the early 312D-1. Scott published only what they called a "service bulletin" for this model rather than a full service manual. The bulletin contains only the circuit board layouts and the sketchmatics for the early 312D-1. I call it the D-1 to distinguish it from the later version with the crystal filters which I call the 312D-2. Scott made NO model distinction between these two on the front panel or on the serial number tags. So you can't tell one from the other without looking inside at the IF strip. I have not seen any Scott bulletin or manual for the D-2. Which is kind of inconvenient because the D-2 uses a different opamp in the IF strip from the uA703s that were used in the D-1. I have no idea what the newer opamp is. If anyone knows what this chip is, please advise. The one in my D-2 has a Scott part number on it rather than a standard JEDEC type number. I can scan and upload the D-1 service bulletin if you need it. But the 348B complete service manual which includes the alignment procedure for the tuner is available from hifiengine.com. You have to join the group but then you can download any of the manuals for free. I recommend it as a good source for service manuals.
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Please scan the 312D-1 service bulletins, that is the tuner I own. And the owner's manual would be nice. Thank you, also thanks for pointing out the service bulletin nature of the service information. I'll get the 348B complete service manual, and I am already a member there. and they also had the 312D-1 service bulletin. Just got these downloaded, thanks!!!!
 
KentTeffeteller said:
Please scan the 312D-1 service bulletins, that is the tuner I own. And the owner's manual would be nice. Thank you, also thanks for pointing out the service bulletin nature of the service information. I'll get the 348B complete service manual, and I am already a member there. and they also had the 312D-1 service bulletin. Just got these downloaded, thanks!!!!
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I emailed that service document to the AK database keeper today. If it does not appear shortly, please send me a PM and I will be happy to share it. I have a 312 C.
 
I am looking at a 312-D on auction. If anyone can please tell me how to differentiate the older and newer ones, I would appreciate it!
 
The one at auction now is the earlier one. There are no external clues, except possibly the serial number. Internally, if you look at the IF strip, you will see 4 black (dark brown with a white dot) integrated circuits with 6 legs arranged between the tall transformers. There are no crystal filters.
 
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