Audio Technica 33 PTG

[RCruz]

Hi

I am planning to use an Audio Technica 33PTG cartridge and would apreciate information regarding it´s best loading in ohm.

A good friend of mine suggested 180 - 220r so that will be my first attempt but as this is a critical build, I would like some more opinions.

Regards

Ricardo

[RCruz]

I have been informed the AT 33PTG is happy with 30~40 ohms.

Any comments ?

I am searching the net and I believe the EAR phono preamp 834P uses a step up TX that loads the MC cart with 50 ohms.... am I getting closer ?

Regards

Ricardo

[merlin el mago]

Becarefor Ricardo, step-up impedance isn't the same that a load resistor. Vinylengine suggest a minimum load resistor of 20 ohms or more

The coil resistance is 17Ω, so the load impedance is 94x the coil resistance. Any value greater than 10x is usually OK.

The series combination of coil inductance and load resistance will have a -3dB point at R/(2πL)

For example if you choose 170 ohms / 2π x 0.070uH (coil inductance) = -3dB at 386Hz

Mine advice is try to left out the -3dB of the ear bandwith in this case is more easy to do with lower resistance possible so:

20 ohms / 2π x 0.070uH (coil inductance) = -3dB at 45Hz not bad far away from mids-lows it's a good choice

That's always theoretically of course fine adjust by ear.

[RCruz]

Where did you find the value 0.070uH ?

Here: http://www.audiocubes2.com/product/A...Cartridge.html

I can read Coil inductance: 70 mu H (1kHz)

I am quite confused with the units

[merlin el mago]

AT33PTG Audio Technica?Greater China?Limited

Sorry are 0.070H = 70uH but the calculations are well done only a typo.

[merlin el mago]

Sorry bad calculated, I trust in Audio Technica web so 70uH = 0.00007H

-3dB point at R/(2πL)

100 ohms / 2π x 0.00007H = -3dB at 227.355Hz very good out of ear bandwith

If was milihenry like Audiocubes web 70mH = 0.07H

100 ohms / 2π x 0.07H = -3dB at 227Hz very bad mid-low range bandwith

I doubt Audiocubes specs, seems the coil inductance very high for a small magnet wire....

[RCruz]

I guess the real value should be 0.7mH (0.0007H)

In this case using 170r I would get 38k6 bandwidth (Hagerman Technology LLC: Cartridge Loading)

Salas indicated me to use between 180 and 220.... I guess 180 should perfectly do it

[merlin el mago]

0.7mH = 700µH = 0.0007H
70µH = 0.07mH = 0.00007H

Inductance Conversion - FREE Unit Converter

Don't worry about the bandwith with 180 ohms:
0.7mH = 40.946 KHz
0.07mH = 409.463 KHz

Mine Denon DL103R has a coil Inductance: 56µH....