Klark-Teknik KT-2A (2A-KT) -- level question

Blue Jinn

Blue Jinn

Rider of the ARPocalypse
Kinda dumb question here, but I believe the KT-2A is designed for "pro" level +4dBu in and out. Is there really a problem using it on "prosumer" -10dBm signal path, or should I bring the level up on the input and back down on the output.? I've had advice that it's fine either way, but would work better bringing the level up, as the compression is dictated by "how hard you hit it." (The level amp would probably have a lower output impedance too.) Looking for opinions/advice.

TIA.
 
Just looked up the (rather poor) user manual and I see it is an "Optical valve compressor". Now, valves, unless a VERY expensive bit of kit, mean lowish gain and rather more noise than a solid state device would give you, it is therefore rather more important to run such gear at its optimum input level. Too low and it won't "compress" and the output will not be super clean.

So, you need about a 12dB boost at the front (easy enough to do with an op amp or Art make a box) but then is the compressor feeding another neg ten device? If so you will need a 12dB attenuator (two resistors!) to prevent overload. All a bit of a kluge?

The bottom line is that compressors, by the very nature of their function, need to operate at an optimum audio level. However, it might well be that inserting the box in the audio chain gives 'some' effect and that might be good enough for your purposes.

Oh! And don't worry about "impedance" it hardly ever matters. LEVEL is the king.

Dave.
 
Blue Jinn said:
Kinda dumb question here, but I believe the KT-2A is designed for "pro" level +4dBu in and out. Is there really a problem using it on "prosumer" -10dBm signal path, or should I bring the level up on the input and back down on the output.? I've had advice that it's fine either way, but would work better bringing the level up, as the compression is dictated by "how hard you hit it." (The level amp would probably have a lower output impedance too.) Looking for opinions/advice.
Click to expand...
Yes there is a problem - you are mismatched on the Front End of the KT-2A - If you plug a -10dBV output into a +4dBu input the signal is coming in 11.79dB quieter than the gear was designed for - so turn something up.
 
Just looked up the (rather poor) user manual and I see it is an "Optical valve compressor". Now, valves, unless a VERY expensive bit of kit, mean lowish gain and rather more noise than a solid state device would give you, it is therefore rather more important to run such gear at its optimum input level. Too low and it won't "compress" and the output will not be super clean.

So, you need about a 12dB boost at the front (easy enough to do with an op amp or Art make a box) but then is the compressor feeding another neg ten device? If so you will need a 12dB attenuator (two resistors!) to prevent overload. All a bit of a kluge?

The bottom line is that compressors, by the very nature of their function, need to operate at an optimum audio level. However, it might well be that inserting the box in the audio chain gives 'some' effect and that might be good enough for your purposes.

Oh! And don't worry about "impedance" it hardly ever matters. LEVEL is the king.

Dave.
 
Radial makes a nice line booster for such purposes, a clean and solid device:

www.radialeng.com

J+4 - Radial Engineering

The Radial J+4 is a -10dB to +4dB stereo preamp that lets you boost a low output unbalanced signal and interface it with a balanced professional audio system.
www.radialeng.com www.radialeng.com

C.
 
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I am not that impressed with that Radial device. I was also wrong to say "impedance does not matter". In this case it does because the K-T unit has an input impedance of only 600 Ohms. That Radial pre amp has the rather peculiar output impedance of 1.6k and therefore will be attenuated by over 11dB. It is also not a good idea to feed transformers from such a high impedance.

Dave.
 
A mono preamp/channel strip could feed the KT2A at+4db.... like a Symetrix 528E. or others. It has the 200ohm out and looks for a 600 ohm load. (528E is a really cool piece with a lot of engineering options.) http://www.symetrix.co/repository/528E_ug.pdf

Then the output of the KT2A +4db would feed your Interface LINE IN which is "unknown ?" but probably can handle +4db... Im assuming its a tracking application being its a mono unit. Line or Mic level instrument...

I wonder what are the interface specs?
 
Thanks everyone. . It'll pass signal at -10dB. I do have an Aphex line level shifter I picked up at a computer surplus place of all things for a few dollars. I think I'll just go ahead and patch in Aphex.
 
Cosmic said:
Radial makes a nice line booster for such purposes, a clean and solid device:

www.radialeng.com

J+4 - Radial Engineering

The Radial J+4 is a -10dB to +4dB stereo preamp that lets you boost a low output unbalanced signal and interface it with a balanced professional audio system.
www.radialeng.com www.radialeng.com

C.
Click to expand...
Thanks. I've had a similar issue sending signals from my recorder to my WA2A. I think I'll order one of these.
 
PorterhouseMusic said:
Thanks. I've had a similar issue sending signals from my recorder to my WA2A. I think I'll order one of these.
Click to expand...
I wanted to correct something I said there....

I meant the WA76 compressor - not the WA2A compressor. The issue is that 76 style compressors don't have a threshold control. You "lower" the threshold by hitting the compressor harder by adjusting the input. My issue is that to get the compressor working like I want - I have to crank the input control - which cause more noise than I'd like.

Just wanted to clear that up.:-)
 
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