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OLDLEE
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Location: Ontario Canada

Sound Scriber schematic

Post: # 3503Unread post OLDLEE
Tue Sep 23, 2008 2:11 pm

Does anyone out there have a schematic for the older tube-type Sound Scriber circa 1950 (I think)? Mine is model LPR1KOS (5 tubes) in leather case with small lift-up front for loading blanks and accessing microphone.
Or does anyone know an Internet site where one can buy a schematic?

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cd4cutter
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Post: # 3505Unread post cd4cutter
Wed Sep 24, 2008 1:56 pm

Generally speaking, there are two essential sources of service information for consumer electronic devices. Prior to model year 1947, the source was the Rider's Perpetual Troubleshooting (PPT) Manuals. These are MASSIVE binders of reprints of manufacturer's service data collected by the Rider group and published for service technicians. You can now find this data reduced to one or two DVD-ROMs from several sellers on eBay. After about 1947, the Rider service ended and that function was taken up by publisher Howard W. Sams. Sams still exists and has a website where you can browse for you model number. You may have to buy a compilation of data from them which will include many other models that you don't want. A third source on the internet is A.G. Tannenbaum:

http://www.agtannenbaum.com/agtannenbaum.root/shop/
Collecting moss, phonos, and radios in the mountains of WNC

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OLDLEE
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Location: Ontario Canada

Sound scriber schematics

Post: # 3506Unread post OLDLEE
Wed Sep 24, 2008 5:20 pm

Thanks, cd4cutter. I hadn't thought of Sams or Riders...good advice. I am much obliged.

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VinzVideo
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Post: # 4682Unread post VinzVideo
Sun Apr 05, 2009 7:03 pm

I was able to get patent information, including schematics, for my mini portable SoundScriber (the one that only cuts the small discs.)
I was able to repair it, and get the little bugger working!

I found the information at
http://www.freepatentsonline.com/

There's a lot of other stuff there too. It might be a longshot, but hey, you never know.

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tape
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Post: # 4850Unread post tape
Fri May 01, 2009 5:20 pm

I found a lot of soundscriber patents there - but none about the little portable one. Could you point to a specific patent?

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VinzVideo
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Post: # 4858Unread post VinzVideo
Sun May 03, 2009 7:28 pm

The patent number is 2952747. If you search for it, it will show up.
You have to be registered to see the PDF files. I forgot my L/P, so I'll probably have to register again. But you should be OK!

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dx7tnt
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Re: Sound Scriber schematic

Post: # 23482Unread post dx7tnt
Thu Feb 21, 2013 10:43 am

Hi

New member here - did a schematic or circuit diagram for the Sound Scriber ever appear? The patents don't seem to give much info on the electronic workings of the machine. I have a 1949 vintage machine, that needs repairing and restoring to bring it up to shape. Any new help would be most appreciated. Looking forward to getting cutting.

Thanks

Rhys

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markrob
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Location: Philadelphia Area

Re: Sound Scriber schematic

Post: # 23491Unread post markrob
Thu Feb 21, 2013 1:22 pm

Hi,

It nice to have a schematic, but I find that old tube based eqipment like this is pretty straightforward to restore ansd troubleshoot if you take your time. In general, replace all of the paper caps with modern film types. The old paper caps are normally leaky. Also, replace the electrolytics. The muti section types can be expensive, so I usually disconnect them and use single axial lead units of similar value and voltage rating. Just doing this is normally all you need to do. You can ususally figure out what is going on in the circuitry by refering to a copy of the RCA tube manual and use it to ID pinouts of the of each tube.

The soundscribers used a magnetic embossing head, so it should be good. If you don't want to restore the old electronics, you can just drive the head from a modern audio amp capable of a few watts into 8 ohms.

Mark

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dx7tnt
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Re: Sound Scriber schematic

Post: # 23525Unread post dx7tnt
Fri Feb 22, 2013 7:30 am

Hi

Thanks for the pointers. I don't know loads about valve equipment, but I have a friend who is extremely knowledgable looking into it for me. Some of the valves aren't giving anything like full emission, and one I don't think is working at all, and they're american spec valves not as common here in the UK so the costs will start increasing if it needs a full set of new valves. It seems like it's half working though so maybe the caps are ok, now they've been re-formed (we brought it up on a variac.) It's just the main problem is that it's quite a small unit, so the circuitry is a nest of point-to-point wiring, that is neither easy to understand, debug or even work on, as it is so random and compact, hence the request for a schematic. My expert probably knows the ins and outs of what's going on, we'd just prefer to see it laid out so we can unpick it.

However, your advice to drive the cutter head from any power amplifier is a great tip. I should have thought of it, but it hadn't yet occurred to me, and I want to get cutting more than I want to use valves so I will bypass the internal circuitry this evening and give it a go. The turntable platter seems to be rotating fine so I think it should work. Another thing I was thinking of doing to it would be to see if I can make the turn table run at half speed, or some easy ratio, so I can cut at 16 and then playback at 45 to get that bit more fidelity and S/N. Time will tell. Will post results, if and when I have them.

Thanks!

Rhys

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markrob
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Re: Sound Scriber schematic

Post: # 23527Unread post markrob
Fri Feb 22, 2013 10:21 am

Hi,

Before you try to drive the head from a modern power amp, measure the DC resistance to make sure its not a 500 ohm head. I don't think they were. The measured DC resistance will be much lower than the actual impedance, so if get readings in the 2-8 ohm range, you should be good to go.

Mark

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dx7tnt
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Re: Sound Scriber schematic

Post: # 23528Unread post dx7tnt
Fri Feb 22, 2013 10:34 am

Thanks for the tip. that was going to be my next question! Is it easy to blow this head up, or the coils? I really don't want to do that so will have to be very careful. Any more thoughts or answers most appreciated. Clever Trolls.

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markrob
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Re: Sound Scriber schematic

Post: # 23529Unread post markrob
Fri Feb 22, 2013 11:04 am

Hi,

Once you verify that the DC resistiance is in a reasonable range, I'd start out by driving it with a 1Khz sine wave at something like 3 Volts AC RMS. If its an 8 ohm head, this would equate to a bit over 1 watt. These heads are not designed to take very much power. I doubt the power amp on the Soundscriber does more than 5 watts. You can determine this by identifying the output valve(s) and looking at the typical operating specs. For example a 6BQ5 (or EL84) running single ended can do about 5 watts pentode connected.

Mark

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dx7tnt
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Re: Sound Scriber schematic

Post: # 23883Unread post dx7tnt
Wed Mar 06, 2013 7:38 am

Hello All

It works! Bypassed the electronics and using small 3W amp for time being, and the machine cuts great! Shallow impression, it's inscribing rather than "cutting" after all, and some issues with tracking if too much bass, but a remarkable introduction to this remarkable world. The platter is noisy and runs about 27rpm, so slowing music down in computer for playback at 45, and playback is remarkably good, on some material. It feels so good, as a recording engineer, to have a concrete product in your hands, especially given the intangible nature of modern digital recording etc. What an insight! Thanks a lot!

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markrob
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Re: Sound Scriber schematic

Post: # 23884Unread post markrob
Wed Mar 06, 2013 8:03 am

Hi,

Glad you were able to get that working.

By running at a slower speed, you will get a bit better performance (half speed mastering).

You can increase the power available to drive the head, which will help you with the high frequencies. 50 watts would be pleanty. Its ok to hit the head with higher power for short tranient peaks. Just make sure your average leves don't get much beyond 3-5 watts and you'll be ok. In general, the head will probably start to distort long before you reach its thermal limits. Adding a 1/2 amp fuse to the head will keep you from doing something bad. You need to boost the highs starting at about 2Khz and ending 8-10Khz (about 10-13db of boost at the extreams). Also, depending on the head response, you might need some cut below 500 hz. These are the RIAA high and low freq turnover points. Do the EQ before you re-sample the audio to the slower rate. After re-sampling, check the spectrum and kill any excess sound in the audio above 6-8Khz (use a lowpass filter with a -12db/oct slope or better). These frequencies will probably not be cut and just end up wasting power and causing excess heat in the head.

Embossing is tricky as the groove geometry tends to be U shaped. This makes it tough for a standard playback stylus to track. It also places some limits on the high frequency performace you can attain becuse the conicial tip, in effect, self erases the highs. You may need to increase the pressure so that you get a really deep groove. At some point, you stop embossing and will start to cut into the base material. That's about the limit to how deep you can go. Still, with some exprimentation, you should be able to get very good results.

Mark

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dx7tnt
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Re: Sound Scriber schematic

Post: # 23885Unread post dx7tnt
Wed Mar 06, 2013 8:20 am

Hi

Thanks for all the tips. Have been experimenting with EQ and Filters - I used to work at a record company getting vinyl cut and manufactured so I know quite a lot about the process, it's just that this is my first practical experience with it. I think one of the main issues, above feeding the head, is the mechanical problems with the turntable, because there's quite a bit of noise transmitting from the motor and all kinds of other mechanical nastyness that you just wouldn't ever want from a platter you're cutting off. I think it needs a proper disassembly and rebuild and lubrication of the motor, if not a completely different motor altogether. Also, because it's build to just record voice at this slower speed, the track width doesn't seem to be very large at all - it tracks so it can fit 15 minutes onto a 7inch disc (all the way from extremes of edge and centre though, already ditched that) I forget what you guys call how many grooves you get per inch, but that anyway, it's like it tracks across quite slowly on its mechanical arm, so a way of increasing that would be interesting, but I'm likely to have to get into completely diassembling and building a computer controlled arm to move the head like on a vinylcutter or traditional lathe. Would make a great project though. also have some doubts about the metal stylus (is that what you call the cutting tip still?) and so it might benefit from a new or smaller one of them. It's given me a lot to think about anyway. One other thing is that I have had a pile of 50 or so of the worst flex-discs in the world - it was a pack of records each one demonstrating some kind of readers digest compilation of mantovani style music, anyway, I've had these things in my record collection for years but have not been able to bin them, and they caught my eye the other day, and they're all single sided! so, now got a big stack of flexis to cut directly on to by way of practice. Really enjoying myself basically. Another ten years and I'll be ready for a go on a Neumann or Scully!

Thanks again.

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