Alctron MA-1 Schematic question
I've recently seen the schematic for the Alctron MA-1. However, there are a couple of features that aren't clear and I hope to get some help from the group.
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On the input side, after XLR1, there are two items labeled S1 and S2. They look like switches. S1 could be a mute switch. S2 looks like it connects XLR1-3 to either R1 or R2, perhaps to compensate for mic Zin.?
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The other question I have is: where is power applied? Alctron's literature says it "operates on 48V, but does not pass phantom power to the mic." OK, but where is the power applied??
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Dan
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Re: Grounding Issue with TSB2590
#P48mems
Aah, OK! So the buzz is due to teh fact that the capsules are not
properly shielded.
The shield must extend as far as possible to cover most of the
capsule. Ideally, even the front of the capsule should be shieded.
Of course, a mesh should be used, to allow sund to hit the
diaphragm.
Le 11/02/2025 à 07:08,
gerttreggertert223 via groups.io a écrit?:
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They work great except for the buzzing. Im just using a
simple p48 circuit so 1 3.3uF cap and a 100k resistor on the xlr
plug.
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Re: Grounding Issue with TSB2590
#P48mems
They work great except for the buzzing. Im just using a simple p48 circuit so 1 3.3uF cap and a 100k resistor on the xlr plug.
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Re: Grounding Issue with TSB2590
#P48mems
The one on the left is a 3-wire capsule, when the one on the
right is a 2-wire.Depending on the circuit, they may be
incompatible.
Apart from the buzz, does it work?
Le 11/02/2025 à 03:45,
gerttreggertert223 via groups.io a écrit?:
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Maybe this is helpful. Ive attached both circuits of the
datasheets of the capsules. On the left is the JLI2590a and on
the right is the dr2501 I used. They look a bit different.?
Should i adjust the wiring?
?
?
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Re: Grounding Issue with TSB2590
#P48mems
Maybe this is helpful. Ive attached both circuits of the datasheets of the capsules. On the left is the JLI2590a and on the right is the dr2501 I used. They look a bit different.?
Should i adjust the wiring?
?
?
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Re: Grounding Issue with TSB2590
#P48mems
The capsules themselves are properly isolated from one another. They also look the same as the originals and i doubt they would go through the steps to make a fake of the tsb2590s. I think they just come out of the same factory under a different name to sell them on other places.?
Is there a way I can reduce the voltage potential the capsules float at? Maybe by adding another cap somewhere? Im not an electrical engineer and honestly dont know what to google for in this situation.?
Thanks for your help :D
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Re: Grounding Issue with TSB2590
#P48mems
I use the shield but only connect it to ground at the XLR. The capsules float at potential above ground and each one is a bit different. They need to be insulated from each other and handling. Also “real” TSB2590’s and I think the Primos have small internal 30pF or so for EMI Protection.? Best Regards,
Jules Ryckebusch?
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On Feb 10, 2025, at 19:13, gerttreggertert223 via groups.io <gerttreggertert223@...> wrote:
? So ive built an Ambi-Alice based on the Instructable by Jules and used em272 capsules. I noticed my mistake (that these are omni and not cardiod capsules) and ordered some TSB2590 knockoffs off of ali. They arrived and sound fine but I get a weird electrical buzzing sound wich gets amplified if i touch the capsules, so i suspect it could be a grounding issue.?
I used 4.7uF Capacitors and 100k ohm resistors for the simple p48 circuit wich worked great with the em272s and should also work fine with the new capsules right?
Is there a way to fix this??
The instructable doesnt use the cable shielding connected to the microphone capsule, could this help or am i gonna destroy the mics by doing that?
Any help would be appreciated :D
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Sorry I Just came across your Message now. Ive got them installed but having a bit of a problem with them as I described in another post :/ If im not able to fix the issue id gladly come back to your offer tho :)
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So ive built an Ambi-Alice based on the Instructable by Jules and used em272 capsules. I noticed my mistake (that these are omni and not cardiod capsules) and ordered some TSB2590 knockoffs off of ali. They arrived and sound fine but I get a weird electrical buzzing sound wich gets amplified if i touch the capsules, so i suspect it could be a grounding issue.?
I used 4.7uF Capacitors and 100k ohm resistors for the simple p48 circuit wich worked great with the em272s and should also work fine with the new capsules right?
Is there a way to fix this??
The instructable doesnt use the cable shielding connected to the microphone capsule, could this help or am i gonna destroy the mics by doing that?
Any help would be appreciated :D
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Re: What is the role of the capacitor in Simpl48 circuit?
OK thanks.
My document was with a 147k resistor, which implied modifying the
preamp (deleting one of the phantom resistors).
Le 10/02/2025 à 18:00, Fuzzyface via
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This is what I have.
In this particular instance I'm doubling up the capsules but
for a single capsule I'd have used a resistor of about 20k.
I think the resistor values should maybe be slightly higher
as 9V at the capsule is pushing it a bit.
?
Sorry to jump in on your post Adam but this info may be
relevant.
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Re: What is the role of the capacitor in Simpl48 circuit?
This is what I have.
In this particular instance I'm doubling up the capsules but for a single capsule I'd have used a resistor of about 20k.
I think the resistor values should maybe be slightly higher as 9V at the capsule is pushing it a bit.
?
Sorry to jump in on your post Adam but this info may be relevant.
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Re: What is the role of the capacitor in Simpl48 circuit?
There's some confusion about what a "simplestp48" is. Can you
post a schemo?
Le 09/02/2025 à 22:52, Fuzzyface via
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Yes, working ok with my standard Zoom F3.?
I'll check the setup tomorrow though as you have me doubting
myself now....... just cautious as I can't find any references
online anymore.
From memory the resistor value is different to that when
using a capacitor. I'm using AOM5024 capsules.
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Re: Tsb 2590 mid side microphone?
#P48mems
Ricardo, I sent emails to your email address. Hope you received the two posts.
Regards,
zephyrmic
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Re: What is the role of the capacitor in Simpl48 circuit?
Thank you Jerry,
I want to use PUI5024 capsule with Evo4 Audio interface, and the xlr output voltage is 47.6V.
I thought 8.5v output voltage is best for long term use/recording and maximum SN ratio, but I could be wrong...
I have experimented with different Simple48 output voltages (10v, 9.5v and 9v) and I did not see a serious change at voltages above 8.5v.
?
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Re: What is the role of the capacitor in Simpl48 circuit?
Yes, working ok with my standard Zoom F3.?
I'll check the setup tomorrow though as you have me doubting myself now....... just cautious as I can't find any references online anymore.
From memory the resistor value is different to that when using a capacitor. I'm using AOM5024 capsules.
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Re: What is the role of the capacitor in Simpl48 circuit?
Are you sure that SimplestP48 works with an unmodified preamp?
Le 09/02/2025 à 22:41, Fuzzyface via
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So what difference will be expected in the recording between
a simpleP48 and a simplestP48 mic?
I've been using Martin's resistor only simplestP48 for a
while and just assumed I would be missing any low frequency cut
off.
I've looked for the YouTube clips for the simplestP48 but
they are no longer there.
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Re: What is the role of the capacitor in Simpl48 circuit?
So what difference will be expected in the recording between a simpleP48 and a simplestP48 mic?
I've been using Martin's resistor only simplestP48 for a while and just assumed I would be missing any low frequency cut off.
I've looked for the YouTube clips for the simplestP48 but they are no longer there.
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Re: What is the role of the capacitor in Simpl48 circuit?
The gentle LF rolloff set by the choice of C value is not going to "cut off" anything. Please read up on single pole filters. If you need a hard cutoff below a specific frequency, the easiest place to get that is the highpass filter available on most field recorders, or by filtering in an audio editor afterwards.
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Re resistor values, the documentation of the SimpleP48 circuitry is superb, and covers all of this quite well. I did a little experimentation with my PUI AOM5024 capsules, but mostly to ensure that I wasn't exceeding the voltage and current ratings for the capsules. I ended up choosing 82k for resistor. I've built two simpleP48 pairs so far with AOM5024 capsules. In one pair, I used 4.7uf caps. In the other pair, which is now semipermanently installed outside, I used 2.2uf. There's still more than enough low-end there.?
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Re: What is the role of the capacitor in Simpl48 circuit?
Regarding "cut frequencies below 70Hz " see
/g/MicBuilders/message/37143
Regarding "8.5v output voltage": I suppose you mean DC voltage
across the capsule Why specifically 8.5?
DC voltage depends very much on the characteristics of the
built-in FET. FET's have quite a large tolerance. Put in the same
conditions, two capsules may show differences of 50%.
You don't mention the vboltage of the power source, which directly
affects the voltage across the capsule.
Le 08/02/2025 à 02:33, Adam Jo5eph via
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Thank you so much everyone.
Is there any formula/equation to calculate resistor and
capacitor values to getting cut frequencies below 70Hz and 8.5v
output voltage?
By the way, I wan to use PUI5024 capsules.
Many thanks.
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Bamboo Jecklin Disk prototype
I recently did some Jecklin Disk's experiments and uploaded pictures and a three-channel test recording to this folder.
The recording was not edited except that the volume was increased slightly.
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Microphones used: Micbuilder's SimpleP48 based on
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The three-channel Jecklin Disk stereo image recording method ?(one mic for the center...) is part of the OSIS 3-2-1 surround recording technique, which Jecklin used to record orchestras. In addition to other known recording methods he utilized two discs to record image and space.
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The three channel Jecklin Image Disk I experimented with in the field is a little larger (and looking like a scarecrow?! :-).?
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A number of original scripts by Jürg Jecklin on this topic are made available by the University of Music and Performing Arts Vienna under the following link (for private use and for study purposes...):
(all scripts are written in Jecklin’s native language...).
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