Pick up transformer AT630
Somewhat difficult to describe this device, especially to someone who does not want one or even knows that one is desirable. Indeed part of the description needs to focus on the device that precedes it, the moving coil cartridge. Audio-Technicas AT630 transformer owes it’s existence to these exotic low output moving coil transducers.
In the same way moving coil (MC) cartridges are superior to moving magnet/iron types, then the lower output MC versions are superior to the higher output MC versions. The superiority is in the form of greater tracking ability, better micro and macro dynamics and a wider frequency response band. Why, well the moving bits, stylus, cantilever, armature and coils are lighter in moving coils and more so in the low output versions. Lighter moving parts are easier to articulate and by definition produce a more precise signal.
If you thought the first two paragraphs are nerdworthy then do not read further. Low output refers the the cartridge output voltage, usually in the range of 0.15mV to 0.4mV or thereabouts. Low output does not mean low energy however, plenty of current is generated by these cartridges. Problem is, well several problems really. Amplifiers, the active electronic boxes we audio people seem to have plenty of, like to see a few volts at their inputs. And whilst there are plenty of amplifiers happy to amplify tiny signals, they generally present a high load impedance to the source.
Now for the nerdy bit … to get the most energy out of a generator (the cartridge) the generator needs to drive into a load that has the same (or close to it) impedance as the generator itself. All low output cartridges have low internal impedances, why, fewer coils, lighter. I told you this was nerdworthy!!
A lot of phono stages, even high end ones, just load up their inputs with resistors that sink valuable signal to ground. The low output cartridge is happy as it is driving into a low impedance. However it is less than optimal turning valuable signal into load resistor heat!! A side effect of this sorry state of electrical affairs is that high frequency noise is favoured over signal in these less than satisfactory input circuits!
The best way to treat a signal from a Low Output MC is to send it into a pick up transformer. Here the voltage will be stepped up whilst current is stepped down, that is the signal is transformed. The transformed signal will now be more suitable for valve and transistor front end circuits of most phono stages. Further more, a carefully made transformer like the AT630 featured here, is made to present an ideal load to the cartridge. This ensures the cartridge is producing the healthiest signal it can. Those of you that think I am talking crap please look up “Maximum Power Transfer Theorem” Page 280 Exploring Electricity and Electronics, by Hazen. Last but not least noise transfer is at least hindered and not aided.
- Frequency response: 15Hz – 80kHz
- Distortion: <0.05% at 1mV
- Suits Cartridge Impedances: 20Ω and greater
- RCA input/outputs plus grounding
- Dimensions: 46W x 38H x 119D
- Weight: 190grams
Last but not Least
This preowned audio-technica AT630 is in very good cosmetic and working condition. The images in this listing are of the actual unit. And you guessed it, we can and will pack it properly for an interstate trip if required.
For an interesting essay by an SUT designer go to Essay
For another SUT available on our site go to Mitchell Cotter