Re: Parallel capsules with simple p48
Others will correct me if wrong, but based on what I've read here
about this:
With Simplest P48 (capsule + resistor + capacitor) you can indeed
parallel the capsules. You use a single resistor/capacitor set,
but you cut the resistor value in half for two capsules, to 1/3rd
for three capsules, etc.
You can apparently also parallel the entire SP48 circuit off the
XLR, which someone suggested might be better for 3 or more
capsules.
My notes say "Could theoretically power ~14 in parallel, but CMRR
degrades with each capsule (because SP48 loads only one of the
6.81k resistors used in phantom); "in the real world you should be
OK putting three or four P48's in parallel" "
Someone on this list (sorry for lack of attribution) also said
"Doubling the number of capsules can improve your SNR by
1/sqrt(2). So going from 1->2 improves things by that much.
Going from 2->4 does so again. Going from 4->8 does so
again. But that's where things get a little iffy. 2 capsules
arranged vertically mostly works because most sources are going to
be in the plane of the mic so you won't get much in the way of
comb filtering between the capsules. By the time you've crammed
eight capsules into one spot, it's going to start having a
noticeable effect. Also, if you look at what 1/sqrt(2) looks like
in dB, it's tiny. It's about a 1.4dB improvement in SNR. I don't
know how tight the tolerances are on the Primo or PUI capsules,
but you may be able to better that by just picking the best of a
batch and using those as single capsules per channel."
There are other considerations, but that about sums it up. :-)
-c
On 2/13/25 15:31, Cram via groups.io
wrote:
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Hi all,?
First post on here - I've done a search through the group but
couldn't find a definitive answer.
I've been mucking around lately with aom5024 capsules to go
along with the clippy mics that I have, and have been quite
happy with their performance. I've got some as PIP, and I've
built some into XLR plugs using the simple p48 circuit to use
with a zoom h5, and these also work a treat.
I've seen a few mentions online about the merits of running two
or more capsules in parallel, and would like to try this myself.
Seems fairly straightforward with the PIP examples online,
however I've been overthinking it in regards to the phantom
power XLR connection and am now double guessing myself.
My question is:
1) can I use the the same p48 circuit I used for a single
capsule, and just wire two capsules in parallel
2) do I do #1 but adjust the cap/resistor values to
accommodate the multiple capsules
3) does each capsule require its own resistor/cap?
Thanks in advance guys :)? ??
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Parallel capsules with simple p48
Hi all,?
First post on here - I've done a search through the group but couldn't find a definitive answer.
I've been mucking around lately with aom5024 capsules to go along with the clippy mics that I have, and have been quite happy with their performance. I've got some as PIP, and I've built some into XLR plugs using the simple p48 circuit to use with a zoom h5, and these also work a treat.
I've seen a few mentions online about the merits of running two or more capsules in parallel, and would like to try this myself. Seems fairly straightforward with the PIP examples online, however I've been overthinking it in regards to the phantom power XLR connection and am now double guessing myself.
My question is:
1) can I use the the same p48 circuit I used for a single capsule, and just wire two capsules in parallel
2) do I do #1 but adjust the cap/resistor values to accommodate the multiple capsules
3) does each capsule require its own resistor/cap?
Thanks in advance guys :)? ??
|
Re: Alctron MA-1 Schematic question
The MA1 circuit is a blatant rip-off of the Triton Fethead
version 2, which is marginally less bad than the version 1.
Le 13/02/2025 à 12:06, Jerry Lee Marcel
via groups.io a écrit?:
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Isn't the cascode an inverter?
Le 13/02/2025 à 11:37, Goran Finnberg
via groups.io a écrit?:
The schematic is in error.
XLR1 Pin 3 goes to XLR 2 Pin 2.
XLR1 Pin 2 goes to XLR 2 Pin 3.
This implies that we get a polarity shift.
Very bad design indeed.
Is this really the original schematic or a fake copy.
.........
Best regards,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden
E-mail: mastering@...
Learn from the mistakes of others, you can never live long
enough to
make them all yourself.??? -?? John Luther
(\__/)
(='.'=)
(")_(") Pyret, Ranglet, Aron, VovVov, Nero, Smurfen &
Pussin:RIP
|
Re: Alctron MA-1 Schematic question
Isn't the cascode an inverter?
Le 13/02/2025 à 11:37, Goran Finnberg
via groups.io a écrit?:
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Show quoted text
The schematic is in error.
XLR1 Pin 3 goes to XLR 2 Pin 2.
XLR1 Pin 2 goes to XLR 2 Pin 3.
This implies that we get a polarity shift.
Very bad design indeed.
Is this really the original schematic or a fake copy.
.........
Best regards,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden
E-mail: mastering@...
Learn from the mistakes of others, you can never live long
enough to
make them all yourself.??? -?? John Luther
(\__/)
(='.'=)
(")_(") Pyret, Ranglet, Aron, VovVov, Nero, Smurfen &
Pussin:RIP
|
Alctron MA-1 Schematic question
The schematic is in error.
XLR1 Pin 3 goes to XLR 2 Pin 2.
XLR1 Pin 2 goes to XLR 2 Pin 3.
This implies that we get a polarity shift.
Very bad design indeed.
Is this really the original schematic or a fake copy.
......... Best regards, Goran Finnberg The Mastering Room AB Goteborg Sweden E-mail: mastering@... Learn from the mistakes of others, you can never live long enough to make them all yourself.??? -?? John Luther (\__/) (='.'=) (")_(") Pyret, Ranglet, Aron, VovVov, Nero, Smurfen & Pussin:RIP
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Re: What is the role of the capacitor in Simpl48 circuit?
Hi Jerry,
You're right, the second one is the simplest48 circuit.
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Re: RCA/Shure Model # MI-559156
Bob,
?
I have bought some very old and dirty microphones at flea markets or recycling stores. I am not a professional micbuilder, but I am always happy when I can find technical information about the microphones and give them a new life.
?
Btw: I also searched on SHARC's website for 559156, but it seems the RCA handmic PDF is the only information they have.
?
559156 site:https://sharc.net/
?
Heinz
?
On Thu, Feb 13, 2025 at 11:54 AM, Bob W8RMV wrote:
Heinz,
I looked again at the RCA handmic link you sent & think I found the schematic for mine.
It shows an unidentified PNP along with the resistors & cap that is on my mic's board.
?
Thank you again!
-Bob
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Re: RCA/Shure Model # MI-559156
Heinz,
I looked again at the RCA handmic link you sent & think I found the schematic for mine.
It shows an unidentified PNP along with the resistors & cap that is on my mic's board.
?
Thank you again!
-Bob
?
?
?
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Re: RCA/Shure Model # MI-559156
Thanx Heinz.
Never thought of searching for a pdf. Duckduckgo didn’t find that.
I did more surgery on it & in the base there is a small amplifier in it.
It has a RCA branded 2N408 germanium PNP that tests good as does the mic cartridge.
It also has a 10uF 15 V cap that surprisingly tests very good for value & ESR.
I imagine 8-12 vdc would be a good supply voltage.
I may reachout to the SHARC’s & see if they have anymore.
Or I may just bypass it to use with my Tempo One transceiver.
?
Thanks again - Bob
?
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Re: RCA/Shure Model # MI-559156
Hi Bob
When I searched Google for:
"MI-559156" filetype:pdf
Two results came up:
Shure OEM Model Prefixes
PDF
MI-559156. 344A4611. 122037. 209468P3. GE. 559853D1. 99A86. 99B86. Base station, 6418, RCA, 97B140D (444var.?) Condenser, amplified, DTMF, handheld, Ericsson/GE ...
South Hills Amateur Radio Club
RCA ?(Courtesy of the RCA and the RCA 500 Series two-way radio forum.)
MI-559156-(4 COND. STK. #241762) TERM. A, B, C & D. MI-559156-A(6 COND. STK. #241763) TERM. A, B, C, D & F. MI-559156-A1(8 COND. STK. #244033) TERM. A, B, C ...
The RCA500mic.pdf contains some MI-559156 relateded amplifier circuits.?
For more information and if other micbuilders don't have any more details on the MI-559156, you can try contacting the South Hills Amateur Radio Club in Pennsylvania. If you're lucky, they may ask their members for a (copy of) a manual or schematic diagrams. at
Hope this helps!
Heinz?
Greetings,
I've a RCA/Shure Model # MI-559156 that I am trying to find a schematic or user manual for.
This mic looks like a 444 or 444D & has a Shure Brothers sticker on the bottom but has some unique circuit construction in the base.
The mic element has only 2 connections so it is not the 444D element.
There are 3 or 4 resistors & a capacitor inside the base and has black, white, red, green cable wire.
I did search old messages here & the interweb but haven't found anything.
I also contacted Shure to no avail.
This is my last hope!
?
73 Bob
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Re: Merging three Capsules on two Preamps?!
If you could briefly sketch the schematic you suggested that would be amazingly helpful!
?
I've attached the Primo EM272 datasheet.? Look at the diagram on the right, that's what I'm referring to.? In the place of the 5 volt battery you can use a 9 volt battery and a higher value resistor, say around 6-10k ohms.? You can use the same battery to power all three capsules, each through its own resistor.
?
On the output side, you have an unbalanced signal with plenty of gain for a recorder.? You can put a resistor from the capacitor to your mic input, and if you connect two capsules that way you can adjust the resistor values to set the ratio between the capsules.? Or use a variable resistor, also called a potentiometer, so that you can adjust it while listening.
?
This will work with electret capsules, it does not quite give you the "XLR mic input for a vocal mic" you were referring to.? However, you could build your own vocal mic using a cardioid pattern capsule and this same approach.?
?
-Scott
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RCA/Shure Model # MI-559156
Greetings,
I've a RCA/Shure Model # MI-559156 that I am trying to find a schematic or user manual for.
This mic looks like a 444 or 444D & has a Shure Brothers sticker on the bottom but has some unique circuit construction in the base.
The mic element has only 2 connections so it is not the 444D element.
There are 3 or 4 resistors & a capacitor inside the base and has black, white, red, green cable wire.
I did search old messages here & the interweb but haven't found anything.
I also contacted Shure to no avail.
This is my last hope!
?
73 Bob
|
Re: Grounding Issue with TSB2590
#P48mems
On Wed, Feb 12, 2025 at 12:26 PM, @MusketenManfred wrote:
Id like to try the metal strainer approach. Where do I ground this to tho? Would I use a ground of one of the xlr connectors?
Yes, connect the metal strainer to pin 1 of one of the XLR connections. It's easy to test if you can borrow a metal strainer from your kitchen. A test lead with alligator clips is useful here.
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Re: Grounding Issue with TSB2590
#P48mems
Id like to try the metal strainer approach. Where do I ground this to tho? Would I use a ground of one of the xlr connectors?
?
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I cant imagine this being the case. As I said in the other thread, apart from the electrical buzz they sound fine. But I think the capsules are different because there wouldve been at least some other people having the same problem with the originals as I just followed the Instructable of the ambi alice. Everything works fine so the Circuit works except for the emi shielding, wich I think is the difference between the originals and the "fakes". I had previously built this mic with 4 em272 primo capsules wich worked great so Id just like to upgrade the capsules to working ones so I dont have to alter the design.?
The easiest solution imo would just be to replace the capsules with original ones.
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Re: What is the role of the capacitor in Simpl48 circuit?
This is different than the schemo in your previous post.
The former has a capacitor to isolate DC, the latter has none.
Both may work but require different values for the resistors.
Le 12/02/2025 à 15:57, Adam Jo5eph via
groups.io a écrit?:
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Another picture for assembled components.
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Re: What is the role of the capacitor in Simpl48 circuit?
Another picture for assembled components.
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Re: What is the role of the capacitor in Simpl48 circuit?
This is the snapshot from the original video.
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We read about your buzz/hum issue, and threw out some solutions for that. Beside that issue, did your 2590 lookalikes work at all? They usually do, even though their specs aren't quite the same.
?
Be warned that "real" 2590s will also show all the same issues, if there are problems with your circuit or shielding. So I would suggest that you keep experimenting with your clones to get them working nicely. You might be happy with the results, and if you do decide later to upgrade, you will be installing the new capsules into a working design.
?
?
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Re: Merging three Capsules on two Preamps?!
Hey Scott,
Pls allow me some beginners questions.
Is what you are describing similar to the simple P48 circuit just with a smaller resistor?
And would 4,7 uF be a "nice big" capacitor?
And the 9V is connected just as Phantompower would be connected?
If you could briefly sketch the schematic you suggested that would be amazingly helpful!
?
Thanks a lot!
?
?
?
?
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Bob W8RMV
