PL2000 Series 2

mlucitt

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#21
All new film caps.
All new 1% metal film resistors.
Joe's DC protect film cap mod.
Joe's secondary voltage reduction mod.
Joe's grounding mod.
Joe's LED mod.
Mark , Joe, and Lee's Opa 2134 Browndog mod.
New mil-spec wiring.
Feet.
IEC socket.
George, you should document all the changes and mods you made (with part numbers) and post it in the documents section so others may find it and you can become that famous PL2000 Series 2 guy.
 

laatsch55

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#22
The balance control and reverb controls have negligible effect. I think the balance control is wired wrong...
 

George S.

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#23
Pretty sure the balance is wired as when I got it, but I will check, easy enough to do. I have old photos from the first time I unsoldered it from the board, and photos from today before I removed the old wire and replaced it. Several weeks ago I pulled it off the board, cleaned and greased it again, and wrote down the ohm meter readings. The pot is unbalanced internally, as the scope led me to believe. It's definitely in that balance pot.
The reverb used to be very minimal, no longer, but then the amount depends on source material, right? Dire Straits appears to be a good source. Have to try it with a mono source.
Tomorrow I'll double check the wiring, and get the part #s together. I bought enough to do two preamps as I'm planning to get another.
 

George S.

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#27
Hooked up rear channels with a Optimus MPA-250 amp and Pioneers. Interesting how the PL2000 works driving front and rear channels. The reverb knob basically works as a volume control for the rear channels. Listening to music, most of the vocals are on the front speakers, with instruments evenly divided depending on the knob setting.
Watched a couple movies as I use this system as a home theater, works OK, decent surround sound. Think it would be better in a very large room with matched amps and all 4 speakers matched.
So the pre amp works properly with all mods as described. Think I'm done with upgrades.
 

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George S.

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#28
Picked up a second PL2000 S2. This one looks all original. No sign of rework on the board and original caps. Appears like it was originally a 220/240v unit and rewired at some point for 120.
I've been doing A/B comparisons between it and the fully modded unit.
The original sounds fine, but thin, constrained, and somewhat flat compared to the modded.
The modded definitely sounds much more open and dynamic, just not constrained at all.
Have to say the upgrades were definitely worth while if one wants a PL preamp.
Mark asked I work up a PDF document with all the part#s and instructions for the upgrades. Will do so and I have most of the parts for the second preamp. Just need to get a couple other projects done first and summer is here. So, it's going to take awhile.
 

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Gepetto

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#30
The original op amps used by PL were nothing to write home about. I designed back in the mid 70s with the original uA739 decompensated op amps. They were a 741 that externalized the compensation components to tailor the performance for your application. I used them for tape head amplification in DIGITAL tape recording applications for computers. They were fine for that because I did not have to listen to it, the computer did.

That is how old that technology is...
 

Wheel-right

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#31
Picked up a second PL2000 S2. This one looks all original. No sign of rework on the board and original caps. Appears like it was originally a 220/240v unit and rewired at some point for 120.
I've been doing A/B comparisons between it and the fully modded unit.
The original sounds fine, but thin, constrained, and somewhat flat compared to the modded.
The modded definitely sounds much more open and dynamic, just not constrained at all.
Have to say the upgrades were definitely worth while if one wants a PL preamp.
Mark asked I work up a PDF document with all the part#s and instructions for the upgrades. Will do so and I have most of the parts for the second preamp. Just need to get a couple other projects done first and summer is here. So, it's going to take awhile.
Looking forward to your future post on this since I'm considering upgrade my 2000II and using it again. Phono section very important to me.
 
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#32
Looking forward to your future post on this since I'm considering upgrade my 2000II and using it again. Phono section very important to me.
I too am looking forward to your PDF as I re-capped that P3600’s electrolytics only and used Nichicons…. A mix of MUSE and other “high end audio”, per their datasheet descriptions. It just sounds thin and tinny to me. I recently found a comparison blog that somebody put together that touts the Elna Silmac elecrolytics as being the go-to parts to use. I’m sure there is a fair amount of experience/brain trust out here that would have recommended which caps are best suited for amp/power/etc sections of audio equipment.
 

Gepetto

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#33
I too am looking forward to your PDF as I re-capped that P3600’s electrolytics only and used Nichicons…. A mix of MUSE and other “high end audio”, per their datasheet descriptions. It just sounds thin and tinny to me. I recently found a comparison blog that somebody put together that touts the Elna Silmac elecrolytics as being the go-to parts to use. I’m sure there is a fair amount of experience/brain trust out here that would have recommended which caps are best suited for amp/power/etc sections of audio equipment.
Do you have the 3600 manual to share? I doubt your caps are the culprit if you replaced them with Nichicon Muse.
 

Gepetto

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#34
I too am looking forward to your PDF as I re-capped that P3600’s electrolytics only and used Nichicons…. A mix of MUSE and other “high end audio”, per their datasheet descriptions. It just sounds thin and tinny to me. I recently found a comparison blog that somebody put together that touts the Elna Silmac elecrolytics as being the go-to parts to use. I’m sure there is a fair amount of experience/brain trust out here that would have recommended which caps are best suited for amp/power/etc sections of audio equipment.
Looking at the schematic, there are only 2 electrolytics in the main signal path (if you have tone out and are using an input other than phono). Primarily C131 and secondarily C107. Both are 22uF. Any other cap you replaced does not matter to the signal path.
 
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#38
Do you have the 3600 manual to share? I doubt your caps are the culprit if you replaced them with Nichicon Muse.
That’s half the problem… I do not have the service manual, just swapped out like value electrolytics for new. There were certainly more than two that I swapped out, including all the ones in the phono preamp circuit.
 

Gepetto

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#39
That’s half the problem… I do not have the service manual, just swapped out like value electrolytics for new. There were certainly more than two that I swapped out, including all the ones in the phono preamp circuit.
I have the schems if you need them. Very simple preamp.
 
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#40
I have the schems if you need them. Very simple preamp.
Thank you Joe. Incredibly simple circuit when you consider I don’t use the turntable section (yet), and the same for the tone controls.
Given the various options of brands and manufacturers, as well as capacitor types: electrolytics, mica, tantalum, film, aluminum, etc., what selection methodology would you use to select replacement caps when doing a rebuild? I went with just replacing electrolytic caps with same value and volts, and used what I believe is a top-tier brand. Mark, you mentioned film…would that have been a better option to use for these caps? Trying to understand how you guys approach a rebuild. Thanks!
 
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