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 Post subject: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Mon 19, 2021 4:44 pm 
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Joined: Apr Mon 19, 2021 1:57 pm
Posts: 27
Hi all,

I'm new to the restoration game and was really excited to find such a good forum full of experts on these vintage goodies. :-)

Mission Statement (I start with the TL,DR): I want to restore my Grandfather's Scott components (LK-72 amp and LT-110 tuner), which I inherited about 25 years ago and used briefly in college. They will be my little tribute to the past & a remembrance of him in the new HiFi/Home Theater zone I'm building next year.

  • I have some general electronics/soldering experience, but I'm no electronics engineer, and will have to borrow some of the tools (o-scope etc).
  • Last time I plugged in the components they worked, but this was >20 years ago. I plan to replace many critical components before powering up. Pots were scratchy for sure.
  • Are the tubes worth using or shall I just replace them immediately? They are surely the original tubes.
  • I'll be running it on the EU 240V/50Hz line with a voltage step-down transformer, any issues I should watch out for?
  • Is it possible to tell what schematic, repair manual, etc revision I need by the Serial # (190894, 149387 I think - blurry photos from family)? I noticed the hhscott website seems to be down, so I'm a bit uncertain where to search for the schematics/manuals, as every place I've found points to hhscott. I have the assembly booklet & mech. assy diagram (no circuit diagram) of the tuner.
  • I need to get the amplifier and tuner from USA to Germany. Anyone have experience shipping these things internationally? Does customs try to assign a high value? (I've owned them for 25y already, but still...)
  • Is there any list of critical components to replace & where to get them? I'll be searching in Germany, unless I wait for the next home trip to pick them up in the USA (who knows when) or ship them here with the hifi gear.
  • Are there any resources or checklists for a non-expert to learn some tips about what to watch out for in such a restoration? (I've got a few local friends I can lean on as well but they're not so familiar with stuff this old)

Thanks for any advice / help, I can try to document what I do to help the next newbies ;-).

Cheers,
Dave
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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Tue 20, 2021 11:12 pm 
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Location: Fernandina Beach, FL
Dave,

I am not ignoring you. I have a few HH Scott amplifiers and tuners. I actually have a couple examples of what you have. I will get time and give you some intelligent answers (hopefully!) soon. I don't want to just shoot from the hip.

BTW, what you have is some excellent equipment. Back to you very soon.

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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 10:08 am 
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Joined: Apr Mon 19, 2021 1:57 pm
Posts: 27
Thanks Don! No rush as I still need to figure out how to get the components to Germany.

I should mention I'm a mechanical engineer with a lot of simpler projects under my belt: subwoofers galore, electronic smoker controller with SSR, PC assembly, a couple solid state power amp kits back in the day. Just completely new to tubes and refurbishing.

Cheers,
Dave


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 1:23 pm 
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Posts: 11080
Location: Sunbury, Ohio 43074
Quote:
I have some general electronics/soldering experience, but I'm no electronics engineer, and will have to borrow some of the tools (o-scope etc).
Last time I plugged in the components they worked, but this was >20 years ago. You probably won't need more than a voltmeter and perhaps a signal tracer if they don't work. A scope is not required but might be helpful if you know how to use one

I plan to replace many critical components before powering up. Pots were scratchy for sure. Does that mean you've powered it up already? ;-) .... clean all pots and switches before powering up. Then again if they remain scratchy once you start testing.

Are the tubes worth using or shall I just replace them immediately? They are surely the original tubes. I would suggest you DO NOT replace the tubes, unless they are bad, or unless you like spending money for no reason. Chances are they are all OK. Wait for the testing phase and see.

I'll be running it on the EU 240V/50Hz line with a voltage step-down transformer, any issues I should watch out for? If it's a 60Hz transformer in the Scott, you may find it overheats on 50Hz. There's really not much you can do about that, since it has to do with the windings themselves. Possibly try and locate an actual 50Hz transformer? But also check...yours may be spec'd for either

Is it possible to tell what schematic, repair manual, etc revision I need by the Serial # (190894, 149387 I think - blurry photos from family)? I noticed the hhscott website seems to be down, so I'm a bit uncertain where to search for the schematics/manuals, as every place I've found points to hhscott. I have the assembly booklet & mech. assy diagram (no circuit diagram) of the tuner. I'd either wait for the Scott site to come back, or try on HiFi Engine.com or AudioKarma perhaps. Even DIYaudio.com

Is there any list of critical components to replace & where to get them? I'll be searching in Germany, unless I wait for the next home trip to pick them up in the USA (who knows when) or ship them here with the hifi gear. Critical in what way? I'd either test, or better yet replace, any electrolytic filter capacitors, and any old paper capacitors, before powering it up


Good luck with your project. Plenty of help here, as you know, and as you'll find out shortly ;-)

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https://www.bbtvtestequipment.com


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 1:43 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13276
Location: Fernandina Beach, FL
Barry H Bennett wrote:
Quote:
I have some general electronics/soldering experience, but I'm no electronics engineer, and will have to borrow some of the tools (o-scope etc).
Last time I plugged in the components they worked, but this was >20 years ago. You probably won't need more than a voltmeter and perhaps a signal tracer if they don't work. A scope is not required but might be helpful if you know how to use one

I plan to replace many critical components before powering up. Pots were scratchy for sure. Does that mean you've powered it up already? ;-) .... clean all pots and switches before powering up. Then again if they remain scratchy once you start testing.

Are the tubes worth using or shall I just replace them immediately? They are surely the original tubes. I would suggest you DO NOT replace the tubes, unless they are bad, or unless you like spending money for no reason. Chances are they are all OK. Wait for the testing phase and see.

I'll be running it on the EU 240V/50Hz line with a voltage step-down transformer, any issues I should watch out for? If it's a 60Hz transformer in the Scott, you may find it overheats on 50Hz. There's really not much you can do about that, since it has to do with the windings themselves. Possibly try and locate an actual 50Hz transformer? But also check...yours may be spec'd for either

Is it possible to tell what schematic, repair manual, etc revision I need by the Serial # (190894, 149387 I think - blurry photos from family)? I noticed the hhscott website seems to be down, so I'm a bit uncertain where to search for the schematics/manuals, as every place I've found points to hhscott. I have the assembly booklet & mech. assy diagram (no circuit diagram) of the tuner. I'd either wait for the Scott site to come back, or try on HiFi Engine.com or AudioKarma perhaps. Even DIYaudio.com

Is there any list of critical components to replace & where to get them? I'll be searching in Germany, unless I wait for the next home trip to pick them up in the USA (who knows when) or ship them here with the hifi gear. Critical in what way? I'd either test, or better yet replace, any electrolytic filter capacitors, and any old paper capacitors, before powering it up


Good luck with your project. Plenty of help here, as you know, and as you'll find out shortly ;-)


Barry is correct. I was typing the next response when he responded. Please, see the below...

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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 1:44 pm 
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Location: Fernandina Beach, FL
Dave,

I understand priorities. In shipping those components, what is especially vulnerable is that soft anodized aluminum face plate. They will bend with the slightest bash to the package. What might be desirable is to at least, remove the face plate and secure it to the bottom or something like that.

As for the electronics, the tuner may well be OK with no work at all. The components in the tuner were not worked very hard. I have on the bench another LK-48 that I have brought back to life. What I find in these amplifiers is that the first filter after the GZ34 may be marginally OK. But they will probably be leaky. The tube sockets are particularly trouble prone. But a good non-abrasive cleaning with DeOxIt D5 and a dental brush (Dentek orange in color). You can feel the resistance when you first start brushing. Soon, the brush gets easier to clean with.

I have had 222, and 299 series (and kit versions) that were totally dead and it was simply tube sockets. Also, tube pins get corrosion on them and cause intermittent operation. Most conventional tubes do not have any kind of plating so I use an Xacto knife and gently scrape the pins individually. (Talking 9-pin, not octal) Switches, potentiometers and jacks can be stiff, stuck or intermittent. WD-40 is my choice of chemical (I know, some will toss harpoons my way about that but...).

The amp that I have on the bench came up first time. But the right channel was weak and distorted with any moderate volume. Problem? One of the two 7189 tubes was not lighting up! Tension adjustment of lugs 4-5, the filament was not successful. So the socket was replaced. I also had replaced the first filter capacitor, 20-20-20-20 µFD with a JJ 40-20-20-20 µUFD and made sure that the 40 µFD section was used last.

Next problem was moto-boating with the volume advanced full when in "Phono". Monitoring the power consumption, it was obvious that this oscillation was really consuming power. The problem was the next filter which essentially measured open. It was a 20-20 µFD @ 450 VDC and 25-25 µFD @ 25 VDC cathode bypass capacitors. The two smaller capacitors were placed at the tube with smaller tubular capacitors and the two other high voltage capacitors were replaced by a JJ 32-32 µFD @ 500 VDC capacitor. So from above it looks OK.

If you do have problems, it will probably be with the LK-72. But that is a gem of an amplifier and is extremely easy to get going. On the plus side, it appears that you have the original tubes. No doubt, the 9-pin tubes are Telefunken, the rectifier is either Mullard or Amperex (or possibly a GE 5AR4) and the 7591 tubes are Westinghouse.

Often, one can determine how much an amplifier was used by the "Loudness" control markings. If the numbers are worn off, it was obviously used a lot. And, heat damage will also show that. I bring up the amplifier slowly with a Sencore PR57 which allows me to ramp up the voltage whilst monitoring power consumption. It becomes obvious quickly if there is a problem. A "gently" used amplifier may well work with original filters. But it is often a time bomb waiting to explode. It depends on how you intend to use the amplifier.

Last note, some American Radionic Ceracap capacitors were paper and later they were Mylar. The Mylar caps are probably still good. The paper ones need to be replaced because they will be (or are) leaky. Resistors are often very, very close to the correct value. HH Scott used good resistors (So did Fisher) and they rarely drift in value. Plate resistors, 100Kꭥ are 1-watt on the 12AX7 preamp tubes which is way overkill. They too should be good.

If you hang out on one of the Audio forums, be advised that there can be a lot of smoke and mirrors there. I frequent there but post seldom because a lot of the members are self-appointed experts. If you want factual information, post a question on this forum and await the answers. Most of the guys here take this seriously and provide detailed, accurate and honest answers. The bovine scat does not flow here!

Take care of that equipment; it is excellent stuff.

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Don


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 2:11 pm 
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Posts: 13276
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One more note, it is normal for the signal strength meter to be fully deflected to the right when the tuner is off.

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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 4:01 pm 
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Joined: Apr Mon 19, 2021 1:57 pm
Posts: 27
Barry H Bennett wrote:
Quote:
I have some general electronics/soldering experience, but I'm no electronics engineer, and will have to borrow some of the tools (o-scope etc).
Last time I plugged in the components they worked, but this was >20 years ago. You probably won't need more than a voltmeter and perhaps a signal tracer if they don't work. A scope is not required but might be helpful if you know how to use one

I plan to replace many critical components before powering up. Pots were scratchy for sure. Does that mean you've powered it up already? ;-) .... clean all pots and switches before powering up. Then again if they remain scratchy once you start testing.

Are the tubes worth using or shall I just replace them immediately? They are surely the original tubes. I would suggest you DO NOT replace the tubes, unless they are bad, or unless you like spending money for no reason. Chances are they are all OK. Wait for the testing phase and see.

I'll be running it on the EU 240V/50Hz line with a voltage step-down transformer, any issues I should watch out for? If it's a 60Hz transformer in the Scott, you may find it overheats on 50Hz. There's really not much you can do about that, since it has to do with the windings themselves. Possibly try and locate an actual 50Hz transformer? But also check...yours may be spec'd for either

Is it possible to tell what schematic, repair manual, etc revision I need by the Serial # (190894, 149387 I think - blurry photos from family)? I noticed the hhscott website seems to be down, so I'm a bit uncertain where to search for the schematics/manuals, as every place I've found points to hhscott. I have the assembly booklet & mech. assy diagram (no circuit diagram) of the tuner. I'd either wait for the Scott site to come back, or try on HiFi Engine.com or AudioKarma perhaps. Even DIYaudio.com

Is there any list of critical components to replace & where to get them? I'll be searching in Germany, unless I wait for the next home trip to pick them up in the USA (who knows when) or ship them here with the hifi gear. Critical in what way? I'd either test, or better yet replace, any electrolytic filter capacitors, and any old paper capacitors, before powering it up


Good luck with your project. Plenty of help here, as you know, and as you'll find out shortly ;-)


Thanks for the helpful info, Barry! This is excellent. I will try to get the tubes sent with the amp or brought here in luggage, if the original ones should still be good. Didn't realize they can still be perfectly fine after some 60 years.

Scratchy pots, this was the case in the late 90's when I last had it powered up ;-). It hasn't been on since then.

Good point about the transformer! Next to the power plug it indicates 50-60Hz, so it looks like I'm in luck and the input transformer should be good for 50Hz as long as I have the voltage step-down transformer for the mains. Whew!

I'll keep holding for the hhscott site, as I'm not currently in a rush and also can't tell (yet) exactly what spec I need. I'll have to check the components vs. some diagrams to find the right "rev" if there's no S/N decoder.

Capacitors: that's exactly what I meant by the critical stuff, I'd prefer to replace them before powering on (electrolytic and paper) in that case. I don't want to risk damaging something or having that "time bomb" effect in a couple years. I have a buddy here who can help me identify which are which caps (well, electrolytic I can spot). What type are these metal can capacitors that I read so much about replacing on many forums? Are they important to replace (either with retro-remakes, or electrolytics hidden inside the original can)?


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 5:28 pm 
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Joined: Apr Mon 19, 2021 1:57 pm
Posts: 27
Thanks Don for the detailed info! I'll ask my Dad to remove the face plate when shipping, if possible. Or package the whole thing in soft foam and peanuts with an oversized box.

It's good news about the tuner if I don't have to do much, I guess I should replace all paper + electrolytic caps on the tuner as Barry suggested to avoid "time bomb" effects? For the amplifier I would definitely do that, because I will likely use it at a decently high power level for rock music listening.

Very good info about the tubes, sockets, contacts, pot cleaning. That will be something to do before powering up, for sure. I've used medium to fine sandpaper for cleaning dirty contacts sometimes in the past.

It's great if I don't have to replace resistors (unless I have a fishy issue that traces to one). I'm guessing the amp had plenty of usage years, but at low volume. This bodes well for all those power-sensitive components.

Haven't looked in many other forums, but in some areas I found a lot of hypothetical craze about how to modify/improve/enchant Scott amplifiers for the "ideal" sound. But I picked this one because it looks quite fact based :-) My speaker cables are 12ga stranded Parts Express and the RCA's are probably a lot of gold-plated Radio Shack stuff. So I'm not after the subjective magic sound you can supposedly get from a $50,000 phonograph or a $2k speaker cable. Just a nice warm tube sound like what my Pop-pop used to play. 8)


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Thu 22, 2021 8:19 pm 
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one51 wrote:
Thanks Don for the detailed info! ...
Haven't looked in many other forums, but in some areas I found a lot of hypothetical craze about how to modify/improve/enchant Scott amplifiers for the "ideal" sound. But I picked this one because it looks quite fact based :-) My speaker cables are 12ga stranded Parts Express and the RCA's are probably a lot of gold-plated Radio Shack stuff. So I'm not after the subjective magic sound you can supposedly get from a $50,000 phonograph or a $2k speaker cable. Just a nice warm tube sound like what my Pop-pop used to play. 8)

There is a lot of rubbish being spouted by some who think that they are smarter than the engineers who designed the Scott amplifiers. They are not. For the best sound and reliability, using what the engineers specified is always best.

I too am NOT into the audiophoolery that is spouted on some other sites. I am into facts only.

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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sat 24, 2021 3:24 am 
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Don Cavey wrote:
There is a lot of rubbish being spouted by some who think that they are smarter than the engineers who designed the Scott amplifiers. They are not. For the best sound and reliability, using what the engineers specified is always best.
I too am NOT into the audiophoolery that is spouted on some other sites. I am into facts only.


+1

I've seen too many valuable vintage audio gear actually damaged/degraded/devalued by so-called audiophile "upgrades" or "improvements". I strongly advise you staying away from this game and use standard restoration techniques only, just needed for safety and long term reliability.
You'll be highly pleased by the sound without "audiophilizing" the units.


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sat 24, 2021 11:57 am 
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Tubologic wrote:
...
I've seen too many valuable vintage audio gear actually damaged/degraded/devalued by so-called audiophile "upgrades" or "improvements". I strongly advise you staying away from this game and use standard restoration techniques only, just needed for safety and long term reliability.
You'll be highly pleased by the sound without "audiophilizing" the units.

Hear, hear, what he said. That is just so true. It makes me cringe to see a stock HH Scott amplifier that has been "Improved" by destroying the original design with the goal of making it "better". It was best on the day it was removed from the original box. You can be assured that the original design and subsequent Scott changes to design were for the best. Armchair self appointed "experts" are not your best advisor.

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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sat 24, 2021 12:55 pm 
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You have a wonderful pair of stereo components and they appear to be in remarkable condition. Did your Grandfather build these Scott Kits? I have an LT-110 tuner and your LK-72 amp's little brother, an LK-30 set up as a bedroom system. (I didn't build them, though.)

There is one small wrinkle in using a US-made LT-110 in Germany. It has to do with the differences in the transmission pre-emphasis (high frequency audio boost) and receiver de-emphasis (complementary high frequency roll-off) used in the two countries. This is used to help reduce high frequency noise, especially when receiving weak signals. US stations have more boost than they have in Germany (and other European countries). So stations there will sound somewhat "muffled" compared to US stations.

The de-emphasis in he tuner can be easily modified by changing the value of a pair of capacitors (and possibly a pair of resistors) in the stereo decoder circuit. (I don't know which components or what their new values should be at the moment.) Alternatively, you could just turn up the amp's treble controls to approximate the difference.

For reference, here is a chart showing the different FM transmission standards used in various countries by international agreement.

Attachment:
File comment: Click on image to enlarge.
ITU FM Transmission Standards.jpg
ITU FM Transmission Standards.jpg [ 303.52 KiB | Viewed 1931 times ]


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sun 25, 2021 12:54 am 
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To change the LT-110 deemphasis for 50µS (European standard) you need to lower the value of C526/527 on the mpx decoder chassis. Exact value is hard to compute because it's a complex filter also including 38/19 KHz rejection circuits. But going from the (original) value of 2,7 nF to something like 1.8 nF should be close enough. To really check the accuracy of the deemphasis curve you need to measure the audio response curve above 5 KHz with an audio signal generator feeding the decoder's input. But don't worry too much: the difference between 75 and 50µS deemphasis is less than 4 dB@ 10 KHz ,which can easily be compensated for with the amp's treble control. (see graph attached below)

Re. the (power) transformer (potential) issue when used on 50 Hz mains which has been mentioned previously: I have a big collection of US (117V/60 Hz) vintage HH SCOTT gear which I'm using with a 240/110V stepdown transformer and never had any transformer failures. Maybe they are running a little bit hotter but apparently Scott used good quality transformers with some safety margin. It's much more important to check the voltage at the secondary of your stepdown transformer and keep it under 117VAC (under load) for better reliability and avoid stressing the parts (tubes, capacitors,...). I would consider 120V as the absolute upper limit for vintage U.S audio gear.


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sun 25, 2021 6:41 pm 
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Dave Doughty wrote:
You have a wonderful pair of stereo components and they appear to be in remarkable condition. Did your Grandfather build these Scott Kits? I have an LT-110 tuner and your LK-72 amp's little brother, an LK-30 set up as a bedroom system. (I didn't build them, though.)

There is one small wrinkle in using a US-made LT-110 in Germany. It has to do with the differences in the transmission pre-emphasis (high frequency audio boost) and receiver de-emphasis (complementary high frequency roll-off) used in the two countries. This is used to help reduce high frequency noise, especially when receiving weak signals. US stations have more boost than they have in Germany (and other European countries). So stations there will sound somewhat "muffled" compared to US stations.

The de-emphasis in he tuner can be easily modified by changing the value of a pair of capacitors (and possibly a pair of resistors) in the stereo decoder circuit. (I don't know which components or what their new values should be at the moment.) Alternatively, you could just turn up the amp's treble controls to approximate the difference.

For reference, here is a chart showing the different FM transmission standards used in various countries by international agreement.

Attachment:
ITU FM Transmission Standards.jpg


Dave


Ah, that's interesting... I probably would leave it as-is, I likely won't use the tuner all that much and I won't be surprised if FM is switched off here in 10-15 years or so :-/. For the amount of radio I would listen to, probably just turning up the treble is a good enough solution. But I'm very glad to know this in case it does sound really strange!


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sun 25, 2021 6:57 pm 
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Tubologic wrote:
To change the LT-110 deemphasis for 50µS (European standard) you need to lower the value of C526/527 on the mpx decoder chassis. Exact value is hard to compute because it's a complex filter also including 38/19 KHz rejection circuits. But going from the (original) value of 2,7 nF to something like 1.8 nF should be close enough. To really check the accuracy of the deemphasis curve you need to measure the audio response curve above 5 KHz with an audio signal generator feeding the decoder's input. But don't worry too much: the difference between 75 and 50µS deemphasis is less than 4 dB@ 10 KHz ,which can easily be compensated for with the amp's treble control. (see graph attached below)

Re. the (power) transformer (potential) issue when used on 50 Hz mains which has been mentioned previously: I have a big collection of US (117V/60 Hz) vintage HH SCOTT gear which I'm using with a 240/110V stepdown transformer and never had any transformer failures. Maybe they are running a little bit hotter but apparently Scott used good quality transformers with some safety margin. It's much more important to check the voltage at the secondary of your stepdown transformer and keep it under 117VAC (under load) for better reliability and avoid stressing the parts (tubes, capacitors,...). I would consider 120V as the absolute upper limit for vintage U.S audio gear.


If we talk about a bit of deemphasis at 10KHz that's fine, I don't like "hot" treble anyway so usually have the treble turned down a bit ;-) Don't get me started about the "crisp" sound of B*se, which (20y ago) had a huge treble boost to persuade yuppies to buy it in the store, never mind the hearing fatigue they'd have after listening to 90's pop for a few hours at home.

Good point about the voltage - I have sold almost all 120V gear I brought with me from the US many years ago, but as far as voltage transformers I kept the best toroidal (300W) one that I had back then. I can check its output voltage under load and make sure it's well below 120V. At least I can feel relaxed that my HH Scott has 50/60Hz printed on the back so maybe if I'm lucky it's a later model where they had the beefiest transformer. I don't think it draws more than 300W (hmm).

By the way Dave asked if my Grandfather built the kits, actually I have no idea. He was a chemist and has a lot of patents for epoxy when it was a hot new invention. Not sure if he was too much into electronics; so he might have bought pre-built. I probably have to guess after checking if the wiring looks like the pre-built ones (by neatness) or what happens when a layperson builds something like this ;-). Or I could ask my relatives... they might remember this.

At the end I'll have the gear hooked up to either my Nubert speakers, some 20y+ old (recently new surrounds) Boston Acoustics bookshelves, or something I custom build for the occasion. It's looking like the transport may take a few months or half a year, because I'm not sure my parents are up for the "serious" packing job that would be needed to ship via USPS.


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sun 25, 2021 7:04 pm 
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Tubologic wrote:
Don Cavey wrote:
There is a lot of rubbish being spouted by some who think that they are smarter than the engineers who designed the Scott amplifiers. They are not. For the best sound and reliability, using what the engineers specified is always best.
I too am NOT into the audiophoolery that is spouted on some other sites. I am into facts only.


+1

I've seen too many valuable vintage audio gear actually damaged/degraded/devalued by so-called audiophile "upgrades" or "improvements". I strongly advise you staying away from this game and use standard restoration techniques only, just needed for safety and long term reliability.
You'll be highly pleased by the sound without "audiophilizing" the units.


+++

The stuff I've seen at some audio conventions was quite eye-opening... there's a lot of art, prestige, and snake oil mixed together. Maybe some of the weird speaker designs have something to them, maybe not. But I've been happy with high-end "prosumer" stuff and the good soundstage I get (e.g. Denon), no multi-$k cd player and ultra damped record player.

And modifying an engineering work of art that defines a bygone era, just because someone on the internet thinks a bunch of additions will make it better... doesn't sound wise :-}


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Sun 25, 2021 8:39 pm 
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one51 wrote:
If we talk about a bit of deemphasis at 10KHz that's fine, I don't like "hot" treble anyway so usually have the treble turned down a bit ;-) Don't get me started about the "crisp" sound of B*se, which (20y ago) had a huge treble boost to persuade yuppies to buy it in the store, never mind the hearing fatigue they'd have after listening to 90's pop for a few hours at home.

Good point about the voltage - I have sold almost all 120V gear I brought with me from the US many years ago, but as far as voltage transformers I kept the best toroidal (300W) one that I had back then. I can check its output voltage under load and make sure it's well below 120V. At least I can feel relaxed that my HH Scott has 50/60Hz printed on the back so maybe if I'm lucky it's a later model where they had the beefiest transformer. I don't think it draws more than 300W (hmm).

By the way Dave asked if my Grandfather built the kits, actually I have no idea. He was a chemist and has a lot of patents for epoxy when it was a hot new invention. Not sure if he was too much into electronics; so he might have bought pre-built. I probably have to guess after checking if the wiring looks like the pre-built ones (by neatness) or what happens when a layperson builds something like this ;-). Or I could ask my relatives... they might remember this.

At the end I'll have the gear hooked up to either my Nubert speakers, some 20y+ old (recently new surrounds) Boston Acoustics bookshelves, or something I custom build for the occasion. It's looking like the transport may take a few months or half a year, because I'm not sure my parents are up for the "serious" packing job that would be needed to ship via USPS.


I have a huge collection of vintage (tube) tuners and noticed that the Scott ones usually have a tendency to sound brighter if compared to other brands (Fisher tuners sounds darker and duller in comparison), maybe this was intentional at the design stage ? I allways convert all my vintage U.S tuners for 50µS deemphasis but leave the Scotts untouched because (to my ears) they sound more balanced like that (here in Europe). But if you feel there's is a lack of upper end just change the two caps and listen...

All H.H Scott gear with the "L" prefix were sold in kit form only, to be assembled by the buyer. (Tuners came with factory pre-assembled/aligned RF front-ends and multiplex decoder units) , thus unless your Grandfather had bought them second hand chances are high he assembled these himself. The building process was very easy and straightforward, no technical knowledge was needed (only soldering abilities) and the Scott assembly manual (in color !) was the best I've ever seen (even better than Heathkits which is considered as the reference). ScottKits were sold in Europe (at least here,in Belgium) but were never successful due to their very high price (here) which made them uncompetitive against ready made (built) Hi-Fi gear.


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Mon 26, 2021 3:50 pm 
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Tubologic wrote:
All H.H Scott gear with the "L" prefix were sold in kit form only, to be assembled by the buyer. (Tuners came with factory pre-assembled/aligned RF front-ends and multiplex decoder units) , thus unless your Grandfather had bought them second hand chances are high he assembled these himself. The building process was very easy and straightforward, no technical knowledge was needed (only soldering abilities) and the Scott assembly manual (in color !) was the best I've ever seen (even better than Heathkits which is considered as the reference). ScottKits were sold in Europe (at least here,in Belgium) but were never successful due to their very high price (here) which made them uncompetitive against ready made (built) Hi-Fi gear.


Aha, I've checked and my Grandfather indeed assembled the kits himself, with my Mom holding the wires when assistance was needed!

I have the assembly booklets for the tuner, but unfortunately they don't seem to be there for the amplifier.


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 Post subject: Re: First-time Restoration: Scott LK-72 and LT-110
PostPosted: Apr Mon 26, 2021 5:16 pm 
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one51 wrote:
...

I have the assembly booklets for the tuner, but unfortunately they don't seem to be there for the amplifier.
If you send me an email address (via PM or whatever), I will send you a scan of the assembly manual. It is invaluable when you want to see how something is done. It is in color and about 9 meg in size.

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