Mr. Bode found that the LM4562 seems to behave quite nicely and that the LT1113 is not well behaved. Mind you, this is just for the first amplification section of the P3 driving the 75us pole and second half opamp. Disregard the data above 20MHz
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LT1013 is Linear Technology's high precision reimplementation of the very low performance, extremely low cost, LM358. LT dramatically shrank the input offset voltage, and boosted the gain-at-DC significantly. And raised the price.
LT1013's datasheet says its gain bandwidth product is 0.7 MHz and its slew rate is 0.4 Volts per microsecond. Which are simply terrible specs for audio! Even the lowly LM741 does better: 1.5 MHz and 0.7 Volts per microsecond (link to LM741 datasheet)
LT1013's datasheet says its gain bandwidth product is 0.7 MHz and its slew rate is 0.4 Volts per microsecond. Which are simply terrible specs for audio! Even the lowly LM741 does better: 1.5 MHz and 0.7 Volts per microsecond (link to LM741 datasheet)
jackinnj,
Thanks to and Mr. Bode for posting your findings.
The first time around on my bench the P-3 had a OPA1656 soldered directly to the PCB.
This time I will fabricate the P-3 PCB's with a socket to test drive additional Op-Amps.
Thanks DT
I used them a score of years ago when I built a micro-processor controlled vacuum tube tracer. In hindsight, the precision wasn't so necessary for vacuum state devices! I didn't know it would be that wild until i ran the scan!
I should note that the graph was done in the low gain setting of the first stage. Will repeat with the high gain setting tomorrow.
Just a quick FYI concerning dual PSU builds.
Finished the first P3 build 3 weeks ago with the kit, single PSU. The sound was so good I ordered a another kit for my second VPI Prime stereo rig. Since the transformers for the kit PCB are not currently available decided to use 2 18V+- ones I had gotten from Randy. Just finished this second P3 build and can report that the 2 PSUs provide a significant improvement over the first build. Have only listened for a day but note the improved soundstage clarity and positioning, a certain secure fullness to the timbral accuracy, and a deathly quiet to all -- so much so that it rivals CDs. New vinyl (such as the just released rsd of Ronstadt's Asylum years -- 4 albums) sound stunning. Of sourse YMMV but in my case am going to retrofit the first build to another dual PSU combo.
AND, thanks again Wayne. Your special skill in designing makes all of us DIYers most appreciative.
Finished the first P3 build 3 weeks ago with the kit, single PSU. The sound was so good I ordered a another kit for my second VPI Prime stereo rig. Since the transformers for the kit PCB are not currently available decided to use 2 18V+- ones I had gotten from Randy. Just finished this second P3 build and can report that the 2 PSUs provide a significant improvement over the first build. Have only listened for a day but note the improved soundstage clarity and positioning, a certain secure fullness to the timbral accuracy, and a deathly quiet to all -- so much so that it rivals CDs. New vinyl (such as the just released rsd of Ronstadt's Asylum years -- 4 albums) sound stunning. Of sourse YMMV but in my case am going to retrofit the first build to another dual PSU combo.
AND, thanks again Wayne. Your special skill in designing makes all of us DIYers most appreciative.
@mhenschel: Took the duplication back to a single outlook in (see the attached). Thought about two AC ins and guessed that because of the low amperage the AC in did not need to be duplicated. The 6 prong umbilical terminals are from Mouser and are expensive -- but I use this on my preamp design to send both polar and non-polar DC current from the outboard PSU to the preamp chassis. The P3 attaches to a 20 amp Furman power conditioner that also runs the 5 sets of power amplifiers I switch to with a system I call "active amp listening." Jim has been sent photos of this preamp design and it, too, uses Wayne's preamp board. Would love to learn more about his background since he is so obviously a brilliant mind.
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Hello Craigl59,
I fully agree with your impressions. I've built 3 versions of the PEARL 3. During the 'test phase' on the wooden board I used a PSU with one transformer followed by two seperated filterboards. Then I switched to a complete
dual mono build.
My impressions are also a better stereo imaging and a better listen into the depth of the recording room.
That is the reason why I have built a few Preamps (Waynes Line Stage, BA-3-pre, Frontend2022, PEARL 2)
and a few poweramps (Mono blocks) in complete dual mono configuration.
This is a lot of effort and costs are going up. For me well worth the expense.
Cheers
Dirk
I fully agree with your impressions. I've built 3 versions of the PEARL 3. During the 'test phase' on the wooden board I used a PSU with one transformer followed by two seperated filterboards. Then I switched to a complete
dual mono build.
My impressions are also a better stereo imaging and a better listen into the depth of the recording room.
That is the reason why I have built a few Preamps (Waynes Line Stage, BA-3-pre, Frontend2022, PEARL 2)
and a few poweramps (Mono blocks) in complete dual mono configuration.
This is a lot of effort and costs are going up. For me well worth the expense.
Cheers
Dirk
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@cubicincher: Exactly. It's "turtles all the way down," right? One channel = one PSU for each stage. Then get a speaker capable of moving a lot of air accurately (I use Tekton Double Impacts) and you're at high end, studio-like performance.
For a fraction of the cost of those uber-expensive cables currently being sold.
For a fraction of the cost of those uber-expensive cables currently being sold.
@mhenschel: those are Randy's flex polar pcbs from 2 years ago. Contact him to see if he has any more.
@Toys4Boys: the boards require attention to the smds and be careful to identify the correct cap parts. They are not all labeled. The + and - regs also should be carefully placed as they are hard to redo. Check the smd values by continuity to their next link. I always find a dead soldering connection that must be redone.