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Hi everyone.
I'm currently in the process of building an OPA Alice based microphone using a NW-700 body and TSB2555B capsule.
Jules instructable is an amazing guide that makes it trivial for anyone to build an OPA Alice using the linked supplies.
But one thing I find lacking is more information regarding the component selection.
As someone who's new to mic building and analog circuitry in general, I wonder how exactly the passive components got selected.
For this reason I've kept most components I plan to use for my mic the same as the provided BOM on PCBWay.
I did substitute some as I think they may perform better or because I already have them in stock.
If anyone could give me some feedback on these choices I would be more confident in my ability to finish this project.
For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance.
The 200 Ohm resistor is just a basic 1% thick film resistor as it doesn't really affect anything important in the circuit AFAIK.
I also plan on replacing the output capacitors with non-polar Panasonic ECE-A1HN4R7U caps.
This is based on the data from Henry at Audio Improv who showed that non-polar caps on the output reduced distortion.
Finally I replaced the 22nF EMI/RF suppression caps with TDK FG14C0G2A223JRT06 as these have a C0G dielectric making them non microphonic.
(BTW these are shown as 0.22nF on the instructables schematic which was super confusing)
I hope my modifications and my reasoning behind them make sense and thanks in advance for taking a look.
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Le 06/06/2024 à 16:03, Lode Willems a écrit?: For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance. The importance of matching these resistors is quite exaggerated. For a strat, the legs going to pin 2 and pin 3 are different. One takes its source from the source of the FET, and the other from the drain, making them of significantly diferent. Typically, the legs have? a difference of about 5 ohms, which is what would result from using 10% tolerance resistors. IMO, there's no need for better than 1% resistors, but a real improvement would be to use a 47r resistor on the source leg and and a 43r on the drain leg.
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Thanks for the positive feedback on my OPA mic instructable. I will look at the ".22nF" on the instructable schematic. I use metal film resistors and 1% for all of it except for the 1Gig, which is 5% or 10% (can't remember off the top of my head). As it is, the design?is already 40dB less distortion than the standard FET based Schoeps circuit and about 12dB of self noise. Component changes or use of .1% resistors are not going to provide measurable improvements. Even using Henry's output capacitors?wont drastically affect the output. You can measure the difference on the bench as he has.? Henry put the OPA mics through testing here:?
I love his quote at the end:?In short, these op-amp boards are the flattest and least distorted mic circuits I’ve ever tested. If you were to describe the “flavor” it would have to be something like “distilled water”. OTOH, like any mic, the main contribution to a “sound” is the capsule, and a good capsule will shine. A poor capsule will have no cover.
All my builds now are with SMD components with "normal" Mouser 1% thick film resistors. I still use the 22nF caps from the instructable as they are RF/EMI protection. Even if they are microphonic, the surrounding circuitry is so low impedance that they won't introduce?anything that the mic capsule isnt already picking up at orders of magnitude louder.?
Jules
On Sat, Jun 15, 2024 at 7:59?AM Lode Willems via <micbuilders= [email protected]> wrote: Hi everyone.
I'm currently in the process of building an OPA Alice based microphone using a NW-700 body and TSB2555B capsule.
Jules instructable is an amazing guide that makes it trivial for anyone to build an OPA Alice using the linked supplies.
But one thing I find lacking is more information regarding the component selection.
As someone who's new to mic building and analog circuitry in general, I wonder how exactly the passive components got selected.
For this reason I've kept most components I plan to use for my mic the same as the provided BOM on PCBWay.
I did substitute some as I think they may perform better or because I already have them in stock.
If anyone could give me some feedback on these choices I would be more confident in my ability to finish this project.
For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance.
The 200 Ohm resistor is just a basic 1% thick film resistor as it doesn't really affect anything important in the circuit AFAIK.
I also plan on replacing the output capacitors with non-polar Panasonic ECE-A1HN4R7U caps.
This is based on the data from Henry at Audio Improv who showed that non-polar caps on the output reduced distortion.
Finally I replaced the 22nF EMI/RF suppression caps with TDK FG14C0G2A223JRT06 as these have a C0G dielectric making them non microphonic.
(BTW these are shown as 0.22nF on the instructables schematic which was super confusing)
I hope my modifications and my reasoning behind them make sense and thanks in advance for taking a look.
-- Best Regards,
Jules Ryckebusch
214 399 0931
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I have built quite a few of these with absolutely normal 1/4 w resistors from Amazon and they perform amazing. Compliments are really made to a high standard these days and most things will be just fine without fancy resistors.
On Sat, Jun 15, 2024, 10:12 AM Jules Ryckebusch via <ryckebusch= [email protected]> wrote: Thanks for the positive feedback on my OPA mic instructable. I will look at the ".22nF" on the instructable schematic. I use metal film resistors and 1% for all of it except for the 1Gig, which is 5% or 10% (can't remember off the top of my head). As it is, the design?is already 40dB less distortion than the standard FET based Schoeps circuit and about 12dB of self noise. Component changes or use of .1% resistors are not going to provide measurable improvements. Even using Henry's output capacitors?wont drastically affect the output. You can measure the difference on the bench as he has.? Henry put the OPA mics through testing here:?
I love his quote at the end:?In short, these op-amp boards are the flattest and least distorted mic circuits I’ve ever tested. If you were to describe the “flavor” it would have to be something like “distilled water”. OTOH, like any mic, the main contribution to a “sound” is the capsule, and a good capsule will shine. A poor capsule will have no cover.
All my builds now are with SMD components with "normal" Mouser 1% thick film resistors. I still use the 22nF caps from the instructable as they are RF/EMI protection. Even if they are microphonic, the surrounding circuitry is so low impedance that they won't introduce?anything that the mic capsule isnt already picking up at orders of magnitude louder.?
Jules
On Sat, Jun 15, 2024 at 7:59?AM Lode Willems via <micbuilders= [email protected]> wrote: Hi everyone.
I'm currently in the process of building an OPA Alice based microphone using a NW-700 body and TSB2555B capsule.
Jules instructable is an amazing guide that makes it trivial for anyone to build an OPA Alice using the linked supplies.
But one thing I find lacking is more information regarding the component selection.
As someone who's new to mic building and analog circuitry in general, I wonder how exactly the passive components got selected.
For this reason I've kept most components I plan to use for my mic the same as the provided BOM on PCBWay.
I did substitute some as I think they may perform better or because I already have them in stock.
If anyone could give me some feedback on these choices I would be more confident in my ability to finish this project.
For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance.
The 200 Ohm resistor is just a basic 1% thick film resistor as it doesn't really affect anything important in the circuit AFAIK.
I also plan on replacing the output capacitors with non-polar Panasonic ECE-A1HN4R7U caps.
This is based on the data from Henry at Audio Improv who showed that non-polar caps on the output reduced distortion.
Finally I replaced the 22nF EMI/RF suppression caps with TDK FG14C0G2A223JRT06 as these have a C0G dielectric making them non microphonic.
(BTW these are shown as 0.22nF on the instructables schematic which was super confusing)
I hope my modifications and my reasoning behind them make sense and thanks in advance for taking a look.
--
Best Regards,
Jules Ryckebusch
214 399 0931
|
Components not compliments
I have built quite a few of these with absolutely normal 1/4 w resistors from Amazon and they perform amazing. Compliments are really made to a high standard these days and most things will be just fine without fancy resistors.
On Sat, Jun 15, 2024, 10:12 AM Jules Ryckebusch via <ryckebusch= [email protected]> wrote: Thanks for the positive feedback on my OPA mic instructable. I will look at the ".22nF" on the instructable schematic. I use metal film resistors and 1% for all of it except for the 1Gig, which is 5% or 10% (can't remember off the top of my head). As it is, the design?is already 40dB less distortion than the standard FET based Schoeps circuit and about 12dB of self noise. Component changes or use of .1% resistors are not going to provide measurable improvements. Even using Henry's output capacitors?wont drastically affect the output. You can measure the difference on the bench as he has.? Henry put the OPA mics through testing here:?
I love his quote at the end:?In short, these op-amp boards are the flattest and least distorted mic circuits I’ve ever tested. If you were to describe the “flavor” it would have to be something like “distilled water”. OTOH, like any mic, the main contribution to a “sound” is the capsule, and a good capsule will shine. A poor capsule will have no cover.
All my builds now are with SMD components with "normal" Mouser 1% thick film resistors. I still use the 22nF caps from the instructable as they are RF/EMI protection. Even if they are microphonic, the surrounding circuitry is so low impedance that they won't introduce?anything that the mic capsule isnt already picking up at orders of magnitude louder.?
Jules
On Sat, Jun 15, 2024 at 7:59?AM Lode Willems via <micbuilders= [email protected]> wrote: Hi everyone.
I'm currently in the process of building an OPA Alice based microphone using a NW-700 body and TSB2555B capsule.
Jules instructable is an amazing guide that makes it trivial for anyone to build an OPA Alice using the linked supplies.
But one thing I find lacking is more information regarding the component selection.
As someone who's new to mic building and analog circuitry in general, I wonder how exactly the passive components got selected.
For this reason I've kept most components I plan to use for my mic the same as the provided BOM on PCBWay.
I did substitute some as I think they may perform better or because I already have them in stock.
If anyone could give me some feedback on these choices I would be more confident in my ability to finish this project.
For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance.
The 200 Ohm resistor is just a basic 1% thick film resistor as it doesn't really affect anything important in the circuit AFAIK.
I also plan on replacing the output capacitors with non-polar Panasonic ECE-A1HN4R7U caps.
This is based on the data from Henry at Audio Improv who showed that non-polar caps on the output reduced distortion.
Finally I replaced the 22nF EMI/RF suppression caps with TDK FG14C0G2A223JRT06 as these have a C0G dielectric making them non microphonic.
(BTW these are shown as 0.22nF on the instructables schematic which was super confusing)
I hope my modifications and my reasoning behind them make sense and thanks in advance for taking a look.
--
Best Regards,
Jules Ryckebusch
214 399 0931
|
Yea, 40 years ago when I was a younger engineer, metal film resistors were an improvement over carbon composition ones of the day. ?Same with capacitors etc. ?I’m certain we will have some golden ear gurus dive in on this one!? Best Regards,
Jules Ryckebusch?
toggle quoted message
Show quoted text
On Jun 15, 2024, at 09:53, Paul E Marchman via groups.io <scarlettamps1@...> wrote:
? Components not compliments
I have built quite a few of these with absolutely normal 1/4 w resistors from Amazon and they perform amazing. Compliments are really made to a high standard these days and most things will be just fine without fancy resistors.
On Sat, Jun 15, 2024, 10:12 AM Jules Ryckebusch via <ryckebusch= [email protected]> wrote: Thanks for the positive feedback on my OPA mic instructable. I will look at the ".22nF" on the instructable schematic. I use metal film resistors and 1% for all of it except for the 1Gig, which is 5% or 10% (can't remember off the top of my head). As it is, the design?is already 40dB less distortion than the standard FET based Schoeps circuit and about 12dB of self noise. Component changes or use of .1% resistors are not going to provide measurable improvements. Even using Henry's output capacitors?wont drastically affect the output. You can measure the difference on the bench as he has.? Henry put the OPA mics through testing here:?
I love his quote at the end:?In short, these op-amp boards are the flattest and least distorted mic circuits I’ve ever tested. If you were to describe the “flavor” it would have to be something like “distilled water”. OTOH, like any mic, the main contribution to a “sound” is the capsule, and a good capsule will shine. A poor capsule will have no cover.
All my builds now are with SMD components with "normal" Mouser 1% thick film resistors. I still use the 22nF caps from the instructable as they are RF/EMI protection. Even if they are microphonic, the surrounding circuitry is so low impedance that they won't introduce?anything that the mic capsule isnt already picking up at orders of magnitude louder.?
Jules
On Sat, Jun 15, 2024 at 7:59?AM Lode Willems via <micbuilders= [email protected]> wrote: Hi everyone.
I'm currently in the process of building an OPA Alice based microphone using a NW-700 body and TSB2555B capsule.
Jules instructable is an amazing guide that makes it trivial for anyone to build an OPA Alice using the linked supplies.
But one thing I find lacking is more information regarding the component selection.
As someone who's new to mic building and analog circuitry in general, I wonder how exactly the passive components got selected.
For this reason I've kept most components I plan to use for my mic the same as the provided BOM on PCBWay.
I did substitute some as I think they may perform better or because I already have them in stock.
If anyone could give me some feedback on these choices I would be more confident in my ability to finish this project.
For the 47, 2.2k and 47K resistors I went with 0.1% 25ppm/C 0603 resistors from the YAGEO RT series.
As I understand it matching the resistors on the XLR3 and XLR2 lines is important for good performance.
The 200 Ohm resistor is just a basic 1% thick film resistor as it doesn't really affect anything important in the circuit AFAIK.
I also plan on replacing the output capacitors with non-polar Panasonic ECE-A1HN4R7U caps.
This is based on the data from Henry at Audio Improv who showed that non-polar caps on the output reduced distortion.
Finally I replaced the 22nF EMI/RF suppression caps with TDK FG14C0G2A223JRT06 as these have a C0G dielectric making them non microphonic.
(BTW these are shown as 0.22nF on the instructables schematic which was super confusing)
I hope my modifications and my reasoning behind them make sense and thanks in advance for taking a look.
--
Best Regards,
Jules Ryckebusch
214 399 0931
|
Indeed they are! That is a very insightful thing to say and I'm glad you're posting such high quality responses.? ;)
-Scott
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Show quoted text
On 6/15/24 09:52, Paul E Marchman wrote:
Compliments are really made to a high standard these days
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
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A bit of perspective on component selection: as far as audible performance goes, the only parts that matter are the capsule and op-amps. If this were food, the capsule is the cut of meat and determines the flavor. Resistors and capacitors are the choice between table salt, sea salt, or kosher salt. You will have to listen very closely to distinguish between them. For example while it is known that non-polar aluminum electrolytic caps distort less than polarized ones, the distortion is so small it can't be measured on most circuits. It is lost under other non-linearities. I wondered if this mic and my interface were clean enough to detect the difference, and surprise!, they are. But notice that test was run injecting the test tones directly, and no capsule was connected. I didn't bother changing the caps on the other boards because the distortion is inaudible.
Also note that the boards I tested were laid out and built by Homero Leal. (Thanks, Homero!) They are similar, but not identical to Jules' layout used by JLI. It turns out with the huge open-loop gain and wide bandwidth of modern op-amps, board layout and grounding matter. In my experience a lot of the rules "everybody knows" about audio grounds, such as single point star grounds, don't apply. There just isn't enough current or power involved with phantom power, and more important are solid contacts and shielding. A filled ground plane on the circuit board with plated through mounting holes so the PCB ground is solidly connected to the mic body is less troublesome than depending on a single point such as the screw of the XLR insert. Tube mics where more power is involved are different.
C0G MLCCs are preferred in audio because they have near constant capacitance with voltage. They are still microphonic, though less so than X7R and other class 2 MLCCs. The high-capacitance dielectrics generate 3rd harmonic when used in filters where a variable signal appears across the cap. In straight DC blocking service, where both sides of the cap rise and fall together, distortion is minimal. Capacitors are slightly microphonic, but a mic capsule is VERY microphonic. If the circuit board is reasonably secured to the mic body, microphonic caps aren't a worry. Note that film caps are usually microphonic, too, and they are not tested for it. The electrodes move slightly, just like a condenser capsule.
In short, your choices are fine. You should have a fine mic when finished. Audio electronics don't usually require extreme precision. In fact, a lot of it is deliberately distorted to replicate some ancient piece of gear that is now rare and expensive. You'll find analog electronics interesting, and some of it will open your eyes for digital design as well. After all, signals on a digital PCB travel as analog voltages.
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This is such a basic question, but please...
One name that is repeatedly repeated in all mic forums is 'Alice'.
What is the original source for this?
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Great question: One of our members, Scott Helmke, designed?a simple (but excellent) version of the Schoeps circuit for use in microphones using??. He called it the "" It was the first?mic I built?and discovered how good a DIY mic could be. I updated the circuit adding in a 1Meg Pot to bias the fet and called it the "Pimped Alice". I also wrote up an instructable on a mic build using a different capsule, the . When I designed?an Ambisonic Mic I asked Scott if I could call it the Ambi-Alice. Then when I came up with the OPA based mic, I asked him if I could call it the OPA Alice.?
Massive Kudo's to Scott!
Jules
On Sun, Jun 16, 2024 at 5:44?AM Glenn Wardle via <glenn.wardle6328= [email protected]> wrote: This is such a basic question, but please...
One name that is repeatedly repeated in all mic forums is 'Alice'.
What is the original source for this?
-- Best Regards,
Jules Ryckebusch
214 399 0931
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Thanks, Jules.
None of this stuff gets done by one person, of course - Dave Latchaw was the first to build one with the TSB-165A capsules that we were just then able to get via a group buy, back when we lived in a wilderness of Panasonic capsules and not much else.? I adjusted the circuit a tiny bit to my preferences and then put a bit more work into a cool housing and a then a project website.
The name came about because I was trying to take photos and failing miserably at representing its size... also back in those days we didn't have bananas for size reference.? Trouble with sizes -> "Alice".
Thanks,
-Scott
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Show quoted text
On 6/16/24 06:04, Jules Ryckebusch wrote: Great question: One of our members, Scott Helmke, designed?a simple (but excellent) version of the Schoeps circuit for use in microphones using this capsule <>?. He called it the "Alice <>" It was the first?mic I built?and discovered how good a DIY mic could be. I updated the circuit adding in a 1Meg Pot to bias the fet and called it the "Pimped Alice". I also wrote up an instructable on a mic build using a different capsule, the TSB2555B <>. When I designed?an Ambisonic Mic I asked Scott if I could call it the Ambi-Alice. Then when I came up with the OPA based mic, I asked him if I could call it the OPA Alice.
Massive Kudo's to Scott!
Jules
On Sun, Jun 16, 2024 at 5:44?AM Glenn Wardle via groups.io <> <glenn.wardle6328@...> wrote:
This is such a basic question, but please...
One name that is repeatedly repeated in all mic forums is 'Alice'.
What is the original source for this?
--
Best Regards,
Jules Ryckebusch
214 399 0931
Linkedin <>
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
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"Components not compliments" ... um ... condiments? :-) (Anonymous)
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I relish this sort of discussion. -Scott On 6/17/24 18:43, Richards wrote: "Components not compliments" ... um ... condiments? :-) (Anonymous)
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ---- "I have ceased distinguishing between the religious and the secular, for everything is holy" - Joe Henry
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Scott says -- I relish this sort of discussion. . . .
I says -- OUCH !! You got me with that one!
I surrender. :-(
( Anonymous)
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Thanks to everyone here for the responses, they gave me a better perspective on the importance of some components.
I did end up going with most of my component choices from my initial post (the .1% resistors aren't that expensive and the C0G caps won't hurt anything) except for the non-polar caps as that would increase the number of items on the BOM while the original caps should be fine.
As for grounding the PCB, I did use a copper pour on all layers connected with plenty of vias. Early in the design process I did have plated mouting holes but in the end those got removed for fear of creating ground loops. Maybe I'll at those back if I ver do a rev 2 :p
For the community I've made my own JLI-2555BXZ3-GP saddle 3d model public so anyone can print it.
I'll attach some pictures of the finished result for closure on this topic ;)
?
 
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So cool to see this! How do you like the Mike? Best Regards,
Jules Ryckebusch?
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Show quoted text
On Jul 11, 2024, at 08:09, Lode Willems via groups.io <micbuilders@...> wrote:
? Thanks to everyone here for the responses, they gave me a better perspective on the importance of some components.
I did end up going with most of my component choices from my initial post (the .1% resistors aren't that expensive and the C0G caps won't hurt anything) except for the non-polar caps as that would increase the number of items on the BOM while the original caps should be fine.
As for grounding the PCB, I did use a copper pour on all layers connected with plenty of vias. Early in the design process I did have plated mouting holes but in the end those got removed for fear of creating ground loops. Maybe I'll at those back if I ver do a rev 2 :p
For the community I've made my own JLI-2555BXZ3-GP saddle 3d model public so anyone can print it.
I'll attach some pictures of the finished result for closure on this topic ;)
?
<inline.0.part> <inline.1.part>
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I've finished this project only a few days ago, but so far so good. Output is very clear and definitely better than what I had before. Only thing of note is that "S" sounds are quite harsh compared to the unmodified microphone, but I guess that that's just the reality and this mic picks it up better :p (Sorry if I don't use the right terminology, not really an audio guy)
It was definitely a fun project and I've learned a lot while doing it.
Thanks again for the amazing instructable.
?
P.S. tip for anyone planning to build this mic, double check the resistor values with a multimeter once fitted, I had tons of noise on the output bc the 2 47Ohm resistors where 10+kOhm in reality, still no idea how that's possible.
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"P.S. tip for anyone planning to build this mic, double check the resistor values with a multimeter once fitted, I had tons of noise on the output bc the 2 47Ohm resistors where 10+kOhm in reality, still no idea how that's possible."
Te noise is from having not enough?current to the Opamp. I learned this once too...
On Thu, Jul 11, 2024 at 11:00?AM Lode Willems via <micbuilders= [email protected]> wrote: I've finished this project only a few days ago, but so far so good. Output is very clear and definitely better than what I had before. Only thing of note is that "S" sounds are quite harsh compared to the unmodified microphone, but I guess that that's just the reality and this mic picks it up better :p (Sorry if I don't use the right terminology, not really an audio guy)
It was definitely a fun project and I've learned a lot while doing it.
Thanks again for the amazing instructable.
?
P.S. tip for anyone planning to build this mic, double check the resistor values with a multimeter once fitted, I had tons of noise on the output bc the 2 47Ohm resistors where 10+kOhm in reality, still no idea how that's possible.
-- Best Regards,
Jules Ryckebusch
214 399 0931
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Paul E Marchman