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llwhtt 8th February 2013 11:23 PM

Sound Technology 1700B
I have a Sound Technology 1700b but no input cable. What is the correct cable to use, the book says "twisted pair", make it or buy it?


PChi 10th February 2013 10:54 AM

No one else has answered so my best attempt is to make it yourself. Unless you need the best common mode noise rejection when twisted pair with an overall screen would be best.

I think that the input connections are just 4 mm terminal post sockets. Possibly the spacing is the 'standard 0.75 inch' so a 'BNC female to double stacking banana plugs adaptor' could be useful for testing single ended equipment. Common mode noise, apart from mains harmonics, is usually not a problem (grosss generalization).

Elvee 10th February 2013 03:09 PM

If you use its balanced capabilities, you need indeed a shielded twisted pair.

If your sources are mainly unbalanced, you can use shielded or coax cable, and strap the (-) and ground posts.
That is the configuration I use myself in 99%+ of cases

llwhtt 20th February 2013 10:47 PM

I found a cable that should just fine- Pomona #1167-36, getting one from Mouser.


toxic ingestion 13th December 2013 04:27 AM

How do you like the 1700b? I have a chance of picking one up and wondered what you thought of it. Thanks.

Elvee 13th December 2013 06:55 AM

I like it, but be sure to test it properly before you buy, because some of the parts do not age very well: the carb comp resistors, switch contacts, analogue optocouplers, potentiometers, etc.

Make it measure its own THD on the most sensitive scale: if there are such issues, they will generate extra noise, and the measurement floor will be too high

TerrySt 13th December 2013 03:01 PM

I have a 1700b also. When working, they are very nice instruments. The only complaint would be the size. They eat up a lot of work bench space. But the are capable instruments and seem to work well.
I like that the calibration procedure can be done without any expensive , rare equipment. It pretty much uses itself to calibrate itself. A good voltmeter, frequency counter and oscilloscope is all that is needed.
But if it isn't working, they are a bear to work on. Depending on which options it has, it can be difficult to get to the bottom side of the boards. The manual suggests for most repairs you cut the leads of the bad component on the top side and tack the new part to the remnants of the leads. For some parts that is not possible. Getting the boards out so you can work on them can be done, but it requires patience. Take careful notes and pictures, because none of the manuals I have found online show the board interconnects very well.
Check that the oscillator works in the low distortion setting. When you switch it to this position, it should turn off the LED and settle in. If if clicks back and forth from fast response to low distortion, then you have some work to do. Hopefully just an alignment, but the circuit uses a light dependant resistor that can fail. It is obsolete, so finding a new part that works may require some circuit modifications and re-tuning. There is info on the web on how to do it though.


desertrunner123 7th July 2016 04:43 AM

I have all the original schematics for the 1700 and 1700b equipment from sound technology

oldsiralan 5th September 2016 11:02 PM

A 1700B sold on eBay came with the following comment: Unfortunately, as far as I know,*the optos are no longer available. Fortunately, I have a second working unit, and*I was able to characterize the optos from that unit --two of the analyzer optos are installed in pin sockets, so they*are easy to remove. For replacement optos*I used the Silonex NSL-32SR3. These are readily available from Digikey. Two of the analyzer optos*act as switches, they are either totally on or totally off and therefore they are fairly easy to substitute, and the NSL-32SR3 works perfectly fine. The other two analyzer optos are critical and need to closely match*the original opto characteristics. For these I used two NSL-32SR3 optos with their LEDs wired in*parallel and used only one of the opto LDR outputs wired in series with a 120 ohm resistor. This combination very closely matches the original*optos taken from my other*working unit. The generator also required the NSL-32SR3 combination--refer to*photos.

1audio 6th September 2016 04:58 AM

I don't think that's necessary for the 1700. I believe there are direct crosses in the Silonex/whatever today. Digikey has them under Luna Special Purpose | Isolators | DigiKey Looking through the original Vactec specs : my guess from several clues is the VTL5C9 which has the fastest response and the highest dynamic range and is the least stable. Off resistance is 50 Meg, on seems to be 100 Ohms I think the NSL32SR2 would be the best choice in their collection and available as 1 piece for $3.45 It should be lower distortion than the Vactec's were.

More info relevant to ST1700 stuff here:

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