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Homebrew AT BP4025 ideas?

 

I'm looking at creating an XY mic for some field recording. I have seen that the Audio Technica BP4035 is a popular choice in this regard.
I've started to think about trying to create something of a replica to this.
I have been looking at Primo capsules, as being in the UK I find it limiting getting hold of supplies that I often see on here.
I have been drawn to the Primo EM204, as it seems to be sensitive for a cardioid.
EM204
Cardioid
-31 dB sensitivity
16 dB self noise
78 dB SNR

Does anyone have experience of this cap and are you able to chime in with any observations or advice for this or other caps? Or for that matter advice in general for an XY mic build?

Cheers
Adrian
 

I used 3 x EM204 capsules for an experimental Mid/Side mic I built into a BM800 body, and was very pleased with the results.? (Picture attached)
I think the EM204 is probably the the best sounding electret capsule I've tried to date?
?
Couple of points ...
? It is sensitive, and has a relatively low max SPL. It will depend on your application whether that is likely to be a problem?
M/S and XY mics are not often used in close micing situations, so it probably won't be a problem
The alternative EM200 may be more sutiable, for a high SPL mic?
?
? I found the EM204 capsules very sensitive to wind noise. You're going to need a decent wind shield of some sort - especially for outdoor use.
?
? I have had problems with Primo capsules if they accidentally have more than the exact specified max? DC bias voltage applied.
Not specifically with the EM204, but some Primo caspules do seem to be less tolerant of? - even small amounts? - of excess DC bias voltage, compared to some of the cheaper electrets.
?
? It's a good sounding capsule, an can be used to create a mic that can 'punch above its weight' as it were.
?
?
?
On Fri, Sep 13, 2024 at 02:12 PM, Adrian Hicks wrote:

I'm looking at creating an XY mic for some field recording. I have seen that the Audio Technica BP4035 is a popular choice in this regard.
I've started to think about trying to create something of a replica to this.
I have been looking at Primo capsules, as being in the UK I find it limiting getting hold of supplies that I often see on here.
I have been drawn to the Primo EM204, as it seems to be sensitive for a cardioid.
EM204
Cardioid
-31 dB sensitivity
16 dB self noise
78 dB SNR
?
Does anyone have experience of this cap and are you able to chime in with any observations or advice for this or other caps? Or for that matter advice in general for an XY mic build?
?
Cheers
Adrian
 

Thanks Arjay,

It seems it could be a good candidate. I never knew you could use opposed cardioids as a figure 8. I assume they are wired out of phase with each other?
For an XY, what circuitry?would be best do you suppose? Would simple P48 suffice, or would it be beneficial to have something more? Wondering if a zener diode couldn't be?employed to protect any overvoltage....
For my purposes I'd not be worried about high SPL, but could consider using an EM200 for another mic that could be used for louder subjects. I like the idea of cashing in (audibly?speaking) on all of the aircraft traffic around me.
With regards to wind shielding, I got hold of a lot of faux fur from a company specialising in blimps and shockmounts?here in the UK. And I am currently doing some CAD for a blimp. That should protect them pretty well.


On Fri, 13 Sept 2024 at 16:55, Arjay1949 <info@...> wrote:
I used 3 x EM204 capsules for an experimental Mid/Side mic I built into a BM800 body, and was very pleased with the results.? (Picture attached)
I think the EM204 is probably the the best sounding electret capsule I've tried to date?
?
Couple of points ...
? It is sensitive, and has a relatively low max SPL. It will depend on your application whether that is likely to be a problem?
M/S and XY mics are not often used in close micing situations, so it probably won't be a problem
The alternative EM200 may be more sutiable, for a high SPL mic?
?
? I found the EM204 capsules very sensitive to wind noise. You're going to need a decent wind shield of some sort - especially for outdoor use.
?
? I have had problems with Primo capsules if they accidentally have more than the exact specified max? DC bias voltage applied.
Not specifically with the EM204, but some Primo caspules do seem to be less tolerant of? - even small amounts? - of excess DC bias voltage, compared to some of the cheaper electrets.
?
? It's a good sounding capsule, an can be used to create a mic that can 'punch above its weight' as it were.
?
?
?
On Fri, Sep 13, 2024 at 02:12 PM, Adrian Hicks wrote:
I'm looking at creating an XY mic for some field recording. I have seen that the Audio Technica BP4035 is a popular choice in this regard.
I've started to think about trying to create something of a replica to this.
I have been looking at Primo capsules, as being in the UK I find it limiting getting hold of supplies that I often see on here.
I have been drawn to the Primo EM204, as it seems to be sensitive for a cardioid.
EM204
Cardioid
-31 dB sensitivity
16 dB self noise
78 dB SNR
?
Does anyone have experience of this cap and are you able to chime in with any observations or advice for this or other caps? Or for that matter advice in general for an XY mic build?
?
Cheers
Adrian
 

Can you share your uk source of faux fur?
 


On Fri, 13 Sept 2024, 18:58 , <jeremy@...> wrote:
Can you share your uk source of faux fur?
 

On Fri, Sep 13, 2024 at 09:16 AM, Adrian Hicks wrote:
For an XY, what circuitry?would be best do you suppose? Would simple P48 suffice, or would it be beneficial to have something more?
I made one pair of cardioid mics using Transsound TSB 140 capsules and simpleP48 powering, and they have been OK for general field recording. I think it's an easy thing to try first; you can always build something more elaborate later.
 

Yes - the 2 side capsules are connected out of phase. The idea was 'borrowed' :) from Jules' great M/S instructable here: ?
?(Here's my take on the same concept: )
?
That application uses 'FETless' electrets, so it's not quite the same with capsules that have integral FETs - like the EM204.
?
The configuration for the mic image in my first post was this circuit, which was constructed onto stripboard:
?
('rogs' is another of my internet aliases! )
?
When it comes to XY it's simpler of course - there's no need to create the differential side channel.
?
The P48 circuit you mentoned is really more suitable for 3 terminal capsules? - like the EM200. It is an ingenious way of creating a very simple 'balanced' input.
Turning the EM204 into a '3 terminal' capsule is possible - but not at all easy! .. Far better to use an EM200, if you are keen to use circuits like the P48?
?
For 2 terminal electrets - like the EM204 - I tend to use this configuration:?
?
It'unbalanced, but as the EM204 capsule output impedance is quite low, it works very well? with single cored screeen cable, with lengths up to at least 3 metres (and probably a bit more!)
( The 6v2 zener diode is included to protect the capsule from overvoltage when 'hot plugged'. )
?
There are commercial versions of this type of interface - the for example.
Of course you can connect the EM204 directly to a PIP ('Plug In Power')? input by simply attaching a 2 core screened cable to the EM204 terminals. (Core to 'HOT' -- screen to 'GND' )
The other end will need a 3.5mm stereo (TRS) jack. Both 'T' (tip) and 'R' (ring) are connected to the cable core (HOT). The 'S' (sleeve) connection is GND.
?
Using the interface I've shown above is just a way of turning a 48 v phantom powered balanced input into a 'PIP' input!
?
I prefer Mid/Side to X/Y. Capsule orientation is less critical - especially in a single enclosure - and you retain the ability to modify your stereo 'image' afterwards, if required...
?
There's lots of options -- but mic building can become very addictive, so beware !
?
?
?
?
?
?
 

Thanks, that's some good info. I'll read up on Jules' link too.?
Do you have that schematic in a larger format? I can't make out what the transistors are properly

On Fri, 13 Sept 2024, 19:22 Arjay1949, <info@...> wrote:
Yes - the 2 side capsules are connected out of phase. The idea was 'borrowed' :) from Jules' great M/S instructable here: ?
?(Here's my take on the same concept: )
?
That application uses 'FETless' electrets, so it's not quite the same with capsules that have integral FETs - like the EM204.
?
The configuration for the mic image in my first post was this circuit, which was constructed onto stripboard:
?
('rogs' is another of my internet aliases! )
?
When it comes to XY it's simpler of course - there's no need to create the differential side channel.
?
The P48 circuit you mentoned is really more suitable for 3 terminal capsules? - like the EM200. It is an ingenious way of creating a very simple 'balanced' input.
Turning the EM204 into a '3 terminal' capsule is possible - but not at all easy! .. Far better to use an EM200, if you are keen to use circuits like the P48?
?
For 2 terminal electrets - like the EM204 - I tend to use this configuration:?
?
It'unbalanced, but as the EM204 capsule output impedance is quite low, it works very well? with single cored screeen cable, with lengths up to at least 3 metres (and probably a bit more!)
( The 6v2 zener diode is included to protect the capsule from overvoltage when 'hot plugged'. )
?
There are commercial versions of this type of interface - the for example.
Of course you can connect the EM204 directly to a PIP ('Plug In Power')? input by simply attaching a 2 core screened cable to the EM204 terminals. (Core to 'HOT' -- screen to 'GND' )
The other end will need a 3.5mm stereo (TRS) jack. Both 'T' (tip) and 'R' (ring) are connected to the cable core (HOT). The 'S' (sleeve) connection is GND.
?
Using the interface I've shown above is just a way of turning a 48 v phantom powered balanced input into a 'PIP' input!
?
I prefer Mid/Side to X/Y. Capsule orientation is less critical - especially in a single enclosure - and you retain the ability to modify your stereo 'image' afterwards, if required...
?
There's lots of options -- but mic building can become very addictive, so beware !
?
?
?
?
?
?
 

I've posted a easier to read PDF on my Google Drive. You can find it here: https://drive.google.com/file/d/1HCo-FlprkyOc7AldyMdqdHUubp-Wjfz_/view?usp=sharing
?
On Fri, Sep 13, 2024 at 10:21 PM, Adrian Hicks wrote:

Thanks, that's some good info. I'll read up on Jules' link too.?
Do you have that schematic in a larger format? I can't make out what the transistors are properly

On Fri, 13 Sept 2024, 19:22 Arjay1949, <info@...> wrote:
Yes - the 2 side capsules are connected out of phase. The idea was 'borrowed' :) from Jules' great M/S instructable here: ?
?(Here's my take on the same concept: )
?
That application uses 'FETless' electrets, so it's not quite the same with capsules that have integral FETs - like the EM204.
?
The configuration for the mic image in my first post was this circuit, which was constructed onto stripboard:
?
('rogs' is another of my internet aliases! )
?
When it comes to XY it's simpler of course - there's no need to create the differential side channel.
?
The P48 circuit you mentoned is really more suitable for 3 terminal capsules? - like the EM200. It is an ingenious way of creating a very simple 'balanced' input.
Turning the EM204 into a '3 terminal' capsule is possible - but not at all easy! .. Far better to use an EM200, if you are keen to use circuits like the P48?
?
For 2 terminal electrets - like the EM204 - I tend to use this configuration:?
?
It'unbalanced, but as the EM204 capsule output impedance is quite low, it works very well? with single cored screeen cable, with lengths up to at least 3 metres (and probably a bit more!)
( The 6v2 zener diode is included to protect the capsule from overvoltage when 'hot plugged'. )
?
There are commercial versions of this type of interface - the for example.
Of course you can connect the EM204 directly to a PIP ('Plug In Power')? input by simply attaching a 2 core screened cable to the EM204 terminals. (Core to 'HOT' -- screen to 'GND' )
The other end will need a 3.5mm stereo (TRS) jack. Both 'T' (tip) and 'R' (ring) are connected to the cable core (HOT). The 'S' (sleeve) connection is GND.
?
Using the interface I've shown above is just a way of turning a 48 v phantom powered balanced input into a 'PIP' input!
?
I prefer Mid/Side to X/Y. Capsule orientation is less critical - especially in a single enclosure - and you retain the ability to modify your stereo 'image' afterwards, if required...
?
There's lots of options -- but mic building can become very addictive, so beware !
?
?
?
?
?
?
 

Thanks, really appreciate all this help and info.


On Fri, 13 Sept 2024, 22:47 Arjay1949, <info@...> wrote:
I've posted a easier to read PDF on my Google Drive. You can find it here:
?
On Fri, Sep 13, 2024 at 10:21 PM, Adrian Hicks wrote:
Thanks, that's some good info. I'll read up on Jules' link too.?
Do you have that schematic in a larger format? I can't make out what the transistors are properly

On Fri, 13 Sept 2024, 19:22 Arjay1949, <info@...> wrote:
Yes - the 2 side capsules are connected out of phase. The idea was 'borrowed' :) from Jules' great M/S instructable here: ?
?(Here's my take on the same concept: )
?
That application uses 'FETless' electrets, so it's not quite the same with capsules that have integral FETs - like the EM204.
?
The configuration for the mic image in my first post was this circuit, which was constructed onto stripboard:
?
('rogs' is another of my internet aliases! )
?
When it comes to XY it's simpler of course - there's no need to create the differential side channel.
?
The P48 circuit you mentoned is really more suitable for 3 terminal capsules? - like the EM200. It is an ingenious way of creating a very simple 'balanced' input.
Turning the EM204 into a '3 terminal' capsule is possible - but not at all easy! .. Far better to use an EM200, if you are keen to use circuits like the P48?
?
For 2 terminal electrets - like the EM204 - I tend to use this configuration:?
?
It'unbalanced, but as the EM204 capsule output impedance is quite low, it works very well? with single cored screeen cable, with lengths up to at least 3 metres (and probably a bit more!)
( The 6v2 zener diode is included to protect the capsule from overvoltage when 'hot plugged'. )
?
There are commercial versions of this type of interface - the for example.
Of course you can connect the EM204 directly to a PIP ('Plug In Power')? input by simply attaching a 2 core screened cable to the EM204 terminals. (Core to 'HOT' -- screen to 'GND' )
The other end will need a 3.5mm stereo (TRS) jack. Both 'T' (tip) and 'R' (ring) are connected to the cable core (HOT). The 'S' (sleeve) connection is GND.
?
Using the interface I've shown above is just a way of turning a 48 v phantom powered balanced input into a 'PIP' input!
?
I prefer Mid/Side to X/Y. Capsule orientation is less critical - especially in a single enclosure - and you retain the ability to modify your stereo 'image' afterwards, if required...
?
There's lots of options -- but mic building can become very addictive, so beware !
?
?
?
?
?
?
 
Edited

Do I create a proper mid/side setup by using 3 microphones => 1 hard left - 1 mid - 1 hard right? I guess by doing so I don't have to? deal with phasing issues?
 

MS is a bit different than that. The Mid mic is cardioid and is panned center. So equal amounts in left and right. The side mic is figure 8. You send it in phase to one side and then invert it and send it out of phase to the other side. What this does in theory is to??mathematically?create an XY pattern.??



On Sat, Sep 14, 2024 at 6:26?AM A Van Der Reijden via <avdreijden=[email protected]> wrote:

[Edited Message Follows]

Do I create a proper mid/side setup by using 3 microphones => 1 hard left - 1 mid - 1 hard right? I guess by doing so I don't have to? deal with phasing issues?



--
Best Regards,

Jules Ryckebusch

214 399 0931

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