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Dynaco PAT 4
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Posted on January 15, 2025 at 13:58:30 | ||
Posts: 67
Joined: June 27, 2006 |
A friend gave me a Dynaco PAT 4 some years ago. I have used it off and on over the years but mostly it just sits on a shelf. I am thinking of getting a power tube amp or maybe a SS power amp kit or updating a 8w tube amp kit I built several years ago. Regardless, I broke out my old turntable and plugged that into the PAT4 and used the headphone out. Sounded OK but the volume was low even with the volume knob all the way up. I tried two different headphones, both easy drivers at only 64 ohms. The cartridge has an average output of 4.7 mV and the specs on the phone input say ma of 10mV. There is a low, cer and high input on the phono on the back. Only the low even worked at all. I am thinking of getting the upgrade kits from Akitika (upgrademydynaco). In the meantime, is this normal? |
Remember the origin of the PAT-5 BiFet?, posted on January 16, 2025 at 13:22:26 | |
Posts: 40054
Joined: May 12, 2000 Contributor Since: April 5, 2002 |
It was Frank Van Alstine at Jensen's Stereo who modified PAT-5s using lower noise RN60D resistors, tantalum and polystyrene signal capacitors, stiffened the power supply and...replaced the LM301 op amps with newer LF356 models which used a combination of bipolar and JFETs. Bypassed the tone control circuits altogether. I used one of his FET-5s in the late seventies replacing a Citation 11. Was pretty darn good but the SP-6 that followed was significantly better. There is a similar story to how Van Alstine modified the Stereo 400 into the Double Dyna which was later adopted by Dynaco as the Stereo 416 including the optional external capacitor bank for the power supply. I took that approach to an Audire power amp at the time with great results. Taught me a valuable lesson as to the qualitative and dynamic advantages of extremely stiff power supplies.
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