BM800 capsule mod

[Technotech]

Hey all,

I've never done a mic mod before, but after doing a light headphone mod, I feel like I'd like to try out a mic mod. I'd like to record a brass instrument, and my current cheap Amazon mic peaks very harshly when I play it even somewhat close, and at a quiet volume.
I've narrowed down on trying a BM800 mod, replacing the capsule with a "TSB-2555BXZ3-GP". I've run into an issue with picking a desirable amplifier circuit, in that shipping from JLI Electronics for the OPA Alice will cost just under $50 USD, which I'm not quite prepared to spend on this board, especially if I'm not familiar with DIY mics yet.

Additionally, shipping the capsule from JLI is also a no-go, as you can imagine the shipping price isn't great either.
Currently, I figure that buying the donor body and capsule from Aliexpress will work, and there is a welcome deal available for nice savings, but I haven't found a clear replacement for the board there.

• The body I'm thinking to use is https://www.aliexpress.com/item/1005001530540883.html and an photo of the internals posted in a review shows that the board inside this body, is probably useless.
• The capsule choice is https://www.aliexpress.com/item/1005004732197698.html which looks very similar to a real 2555BXZ3, but I suppose the only way to know, is to try it.
• The board I'm considering is https://www.aliexpress.com/item/1005005996097078.html, but I am far to inexperienced to know whether this will work. A review shows somebody using this board in a similar project though.

Alternatively, I did check PCBWay, which oddly quotes 1 assembly, and 20 assemblies of the OPA Alice at the same price ($34 USD). I've also never used PCBWay, so I'm unsure if this calculated price will stick.

Are there any better alternatives for these parts in the OCE region? It seems shipping prices from familiar suppliers is quite a bit more for here, and I wouldn't mind using Aliexpress parts if they work. Any help would be greatly appreciated.

 

[pmfalcman]

Consider this:

https://groupdiy.com/threads/simple-quiet-mic-with-an-electret-capsule.88953/

I'm really happy with the outcome. The circuit and the capsule.

Audioimprov, if I remember correctly, compared 3 electret Ali capsules and the one you're planning to buy came out as the worst soundwise while being the most expensive one.

And, as @k brown suggested get a BM 700 body. For better headbasket shape.

From my (relatively limited but pleasant) experience with PCBWay, the price they give you after evaluation doesn't change. You should be careful though and do not go for their default (shown) shipping agent. There's a list of available options and though one needs to wait longer, the cost can be muuuch lower.
Also play with quantities. The default qty is 5 but you can get more for the same price.
At least it works for unpopulated PCBs (that's what I order).

I live in Europe, not Australia (not anymore anyway) so YMMV

P. S. @rogs builds his circuit on stripboards and he gives nicely detailed build instructions on the site. Might be more convenient option for you.

 

[Technotech]

Thanks for your reply! I thought that the electret capsule I linked would work well since it looks very identical to the real 2555 in my eyes.
I read through the Audioimprov blog that you mentioned (I believe this is the one you meant? https://www.audioimprov.com/AudioImprov/Mics/Entries/2019/9/7_More_Electret_Capsules.html)
Based on that, I suppose I'll opt for https://www.aliexpress.com/item/4000016436315.html instead, given that's what is linked in the blog post (unless there's a better option to go for). I would like to avoid requiring phantom power, so I believe that limits me to electret capsules.
Is it known if this aliexpress capsule is equivalent in quality to an actual TSB2555?

 

[Khron]

I would like to avoid requiring phantom power

On one hand, the rest of the circuitry WILL require phantom power (coming from your preamp / interface / mixer / whatever you connect the mic to, unless you're aiming for battery-power..?)

On the other hand, i'm assuming you mean a voltage booster for externally-polarized condenser capsules. But even those you could use with "just" whatever voltage is left from the phantom power fed to the mic - MXL 2001, Neumann U87 (non-A), AKG C414EB P48 seem to manage just fine.

 

[Technotech]

A bunch of the videos on Youtube that use the TSB2555 don't seem to require phantom power, so I was under the impression that it would not require extra power?

 

[Khron]

A bunch of the videos on Youtube that use the TSB2555 don't seem to require phantom power, so I was under the impression that it would not require extra power?

I don't enjoy being a pedant, but certain words / expressions have certain meanings - otherwise, all communication breaks down and ends up being meaningless. Surely you agree?

https://en.wikipedia.org/wiki/Phantom_power

Please do try NOT to confuse that, with a capsule requiring a polarization voltage (or not).

 

[k brown]

A bunch of the videos on Youtube that use the TSB2555 don't seem to require phantom power, so I was under the impression that it would not require extra power?

Phantom power is primarily used to power the impedance converter and output circuitry of a microphone. A seondary circuit boosts the phantom power to polarize capsules that require external polarization. Mics with electret capsules don't need to provide power to the capsule.

Perhaps when you said 'phantom power', you meant capsule polarization voltage? If so, then the 2555, being an electret, doesn't require external polarization.

The capsule you linked to is considerably better than the 2555, but the samples I bought were quite a bit brighter.

 

[Technotech]

The capsule you linked to is considerably better than the 2555, but the samples I bought were quite a bit brighter.

Interesting, "considerably better" is not what I was expecting.

https://en.wikipedia.org/wiki/Phantom_power

Please do try NOT to confuse that, with a capsule requiring a polarization voltage (or not).

Perhaps when you said 'phantom power', you meant capsule polarization voltage? If so, then the 2555, being an electret, doesn't require external polarization.

I believe that is what I meant. My understanding is that most 34mm capsules are LDC capsules and require external polarisation. I read that electret capsules will generally be between 1-10V, but the Aliexpress pages do tend to be a bit vague on that, so I was trying to make sure. I might still not understand it though so I do apologise in advance if that is the case.

Phantom power is primarily used to power the impedance converter and output circuitry of a microphone.

To clarify, what does this mean for a setup like the one I am describing? Would a 25mm electret capsule + OPA Alice/OPIC.41 require 48V phantom power? (Sorry if that's a very basic question)

Finally, I might also ask another (perhaps similarly basic?) question.

And, as @k brown suggested get a BM 700 body. For better headbasket shape.

I'm reviewing options for that. Are there any recommendations between cheap BM700s and cheap U87s (aside from the shock mounts, for which the BM700 would seem to be better given it's not all plastic)?
U87 clone: https://vi.aliexpress.com/item/1005006053782365.html
BM700: https://vi.aliexpress.com/item/1005005081212544.html

 

[Khron]

I read that electret capsules will generally be between 1-10V

Well, that'll also depend whether they do or don't have a built-in JFET. The 2555 does not; the ones that do, will have the rear of the capsule made out of PCB material (FR4 with solder-resist etc; i've only seen green and blue so far).

To clarify, what does this mean for a setup like the one I am describing? Would a 25mm electret capsule + OPA Alice/OPIC.41 require 48V phantom power? (Sorry if that's a very basic question)

Yes it would. The opamp's not going to power itself, out of thin air

 

[rogs]

....... Would a 25mm electret capsule + OPA Alice/OPIC.41 require 48V phantom power? (Sorry if that's a very basic question)

Yes -- THIS OPIC PAGE shows the ciruitry required to interface a 'FETless' electret capsule.....
• An impedance converter powered by 48V phantom power.
• No separate capsule polarisation voltage circuitry required.

 

[Technotech]

Yes it would. The opamp's not going to power itself, out of thin air

Fair enough on the opamp's part I suppose! I've been somewhat attached to the 2555 after watching this video,

(at the linked timestamp he makes a distinction about requiring a preamp). It doesn't seem like he requires external power for his setup, which is why I'm hoping I could find something that does the same, but I might still be understanding it wrong.

 

[Khron]

(at the linked timestamp he makes a distinction about requiring a preamp)

Yes he does, but he is talking about the USB-C mic that's the subject of the video, NOT the opamp board from JLI.

What were / are you intending to use this mic for / with?

 

[Technotech]

What were / are you intending to use this mic for / with?

I was hoping to record my brass instrument (euphonium to be specific), and also for general voice use. I've seen demos of singing and guitar playing with the 2555 so I figured that it would work.
I don't have a phantom power supply or mic preamp as I haven't owned any "professional" mic equipment before, which is why I was trying to avoid the requirement of one.
(The two opamp boards I've been looking at are https://www.pcbway.com/project/shareproject/OPIC_Microphone_fce72e5c.html and https://www.pcbway.com/project/shareproject/Dual_OPA__Alice__Microphone_Circuit.html but it's worth me noting that I'm not really sure what the difference is between the two, aside from the OPA Alice using an OPA1642, and the OPIC using an OPA1641)

 

[Khron]

I was hoping to record my brass instrument (euphonium to be specific)

Ok, how? Phone, computer, stand-alone recorder? Tape recorder? Wax cylinder?

 

[Technotech]

Ok, how? Phone, computer, stand-alone recorder? Tape recorder? Wax cylinder?

Through my computer into a DAW. A basic setup, I guess.
Current mic peaks atrociously when I attempt to record it, but is fine for voice use.

 

[Khron]

Through the built-in sound card?

 

[Technotech]

Through the built-in sound card?

Yes, I'm guilty as charged. No preamp... no sound card either. Still a newbie to proper audio setups.

 

[Khron]

In that case, don't get your hopes up about low-noise.

And there's no need to spend hundreds on gear - you must be able to snap up something like a Focusrite Saffire 6 USB 2.0, or a Scarlett Solo or 2i2 (any generation ) for 50 bucks or so. Used, of course...

 

[zawad_tahmid]

It doesn't seem like he requires external power for his setup, which is why I'm hoping I could find something that does the same, but I might still be understanding it wrong.

Well, you can power it up from usb.
Here's the Mark Kahrs' schematic from micbuilders https://groups.io/g/MicBuilders/attachment/36116/1/newamp.pdf
But you should definitely get a preamp, there are some decent budget preamps out there.

 

[Technotech]

you must be able to snap up something like a Focusrite Saffire 6 USB 2.0, or a Scarlett Solo

But you should definitely get a preamp

Ebay is only showing mounts/stands for those for some reason. I’m wary of Facebook Marketplace, but I have spotted a Scarlett Solo + Scarlett Studio CM25 for a good price (both are >5 years old). Is the stock CM25 any good, or would be better (or even possible) to change the capsule out (without buying a new PCB for the inside of the mic)?