I've had my PAT-4 since 1975. For the second time since then, I tore it down again to rebuild for fun.
Over the years (decades) I found there were things I never used, such as the low filter switch, the high filter switch, the A-B-Blend switches and the front panel input/output phone jacks. Loudness I used rarely. I got rid of my turntable after my vinyl classical collection was destroyed by tropical storm Harvey, and I haven't had a tape deck in years. So I decided to get unused stuff out of the circuit. Except the Phono input; it just seemed wrong to exclude that.
With all this talk about bypassing the tone controls, I added that capability using the now available A-B-Blend switches, which gives me the ability to use or bypass each tone control separately. So I can bypass treble but keep the bass, and add a bit of bass to substitute for the Loudness switch, so presto, the Loudness switch is out of the circuit as well. My new Loudness switch is the "B" rocker switch.
I remember the high filter rotary switch assembly was a pain to assemble, but then I never used it, never. So it is replaced by a 3-position rotary switch that gives me Stereo-Blend-Mono capability. A-Only Mono and B-Only Mono I no longer have, but I never used that anyway.
I put in the Darlington transistor upgrade for Q4.
The thing sounds pretty good to me.
A request: Your advice on what I did to defeat the two unused low-level inputs, tape head and special. Just disconnecting them made for a terrible squeal when they got selected, so I grounded those selector switch lugs. It still makes a noise, but not nearly as bad. Of course I'll avoid that setting any way. Image attached. Many thanks.
Over the years (decades) I found there were things I never used, such as the low filter switch, the high filter switch, the A-B-Blend switches and the front panel input/output phone jacks. Loudness I used rarely. I got rid of my turntable after my vinyl classical collection was destroyed by tropical storm Harvey, and I haven't had a tape deck in years. So I decided to get unused stuff out of the circuit. Except the Phono input; it just seemed wrong to exclude that.
With all this talk about bypassing the tone controls, I added that capability using the now available A-B-Blend switches, which gives me the ability to use or bypass each tone control separately. So I can bypass treble but keep the bass, and add a bit of bass to substitute for the Loudness switch, so presto, the Loudness switch is out of the circuit as well. My new Loudness switch is the "B" rocker switch.
I remember the high filter rotary switch assembly was a pain to assemble, but then I never used it, never. So it is replaced by a 3-position rotary switch that gives me Stereo-Blend-Mono capability. A-Only Mono and B-Only Mono I no longer have, but I never used that anyway.
I put in the Darlington transistor upgrade for Q4.
The thing sounds pretty good to me.
A request: Your advice on what I did to defeat the two unused low-level inputs, tape head and special. Just disconnecting them made for a terrible squeal when they got selected, so I grounded those selector switch lugs. It still makes a noise, but not nearly as bad. Of course I'll avoid that setting any way. Image attached. Many thanks.
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