Dynaco pat-5

[Mitchell]

Hi you Dynaco buffs.

What are the differences between the pat-5 and the BiFet pat-5? Anyone know?
I only have a schematic of the pat-5 bifet. One difference is the Pat-5 Bifet has a hi-lo phono switch.

 

[cademan]

I have the PAT-5 and mine does not have the hi-lo phono switch, but has hi-lo individual RCA inputs, so maybe this is the difference unless someone knows more about it.

 

[Renzor213]

I've owned an original PAT-5 since new, but haven't used it in year's. Main difference is the FET driver stage IC used in the newer model, for supposedly lower noise than the original's Bi-Polar unit. As mentioned, hi-lo phono level, different faceplate around the volume knob and aluminum push button's. Very flexible unit's, with 2 phono input's, EQ processing loop, good tone control design, speaker swithing and more. The low filter's a joke though, with a basic 1st order filter design that really cut's into the bass. Never liked the plastic push button's on earlier Dynaco's, so later got the aluminum job's. Probably have lot's of the plastic's laying around somewhere.

 

[Dr Tinear]

IIRC, the original PAT-5 used an LM301 op amp as the gain element on the line and tone control board. The BiFET changed this part to an LF357 FET-input op amp with a much higher slew rate than the LM301. Dynaco also upgraded some of the passive parts (mostly caps) when they made the op amp change.

 

[LeonRoose]

Plastic Push button caps

I've owned an original PAT-5 since new, but haven't used it in year's. Main difference is the FET driver stage IC used in the newer model, for supposedly lower noise than the original's Bi-Polar unit. As mentioned, hi-lo phono level, different faceplate around the volume knob and aluminum push button's. Very flexible unit's, with 2 phono input's, EQ processing loop, good tone control design, speaker swithing and more. The low filter's a joke though, with a basic 1st order filter design that really cut's into the bass. Never liked the plastic push button's on earlier Dynaco's, so later got the aluminum job's. Probably have lot's of the plastic's laying around somewhere.

Do you still have some of those plastic push button caps? If so, are you willing to part with a couple? Will pay..