Blue Microphones Spark capsule

"This is a new capsule design for Blue, not found in any of its other products to date. " - Recording Hacks

Currently have it on my bench - so!

Capsule isn't anything else than chinese TSB-2555 electret transducer - in fact really decent.
Yes, it is external polarised
It can ba made also with different electret transducers, especially LDC (like AKG "teflon" electrets).
Circuit have some bugs, like HPF adaptation - nasty, nasty.
I did modification of the circuit, removed HPF (owner don't need it) and reused switch to change capsule mode - electret/external polarised.

This microphone can be usefull tool after moodification

Wait a minute - electret, AND external bias? What the..?

Yeah, why not? Different sensitivity - electrode is electrode - slightly different material but can be polarised externally

Do you think there would be any luck throwing a large capsule on this mic with the same circuit?

Abiquaengineer said:

Do you think there would be any luck throwing a large capsule on this mic with the same circuit?

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It not really have sense -  i know that gearslutz beloved modder do that - but still - i don't see any sense.
Why?
First of all - hpf adaptation of the circuit is really poor - i would remove it for better performance of the microphone.
Polarisation voltage is less than 40V - not much as for LDC.
With most chinese capsules you will get bright response in this circuit and headbasket.
You can reuse hpf switch to make optional use of original capsule as electret without extra polarisation.
Of course you will get less sensitivity, but this microphone is pretty loud.
Why use it as typical electret?
Because this capsule is pretty fine and without extra voltage it sounds much more smooth.
550$ microphone use this capsule - so it can't be bad i think
http://recordinghacks.com/microphones/Ear-Trumpet-Labs/Edwina

What's wrong with the HPF?

abbey road d enfer said:

What's wrong with the HPF?

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Original input topology is the same as we talk about in "5-pattern mic circuit" topic - two 1gohm resistors, cap in series, DC and AC on one node.
HPF is made with the input cap + simply added 39Mohm resistor to ground.
I'm not a fan of messing with anything on the input  at high impedances (also pad and hpf in u87 style).

ln76d said:

Original input topology is the same as we talk about in "5-pattern mic circuit" topic - two 1gohm resistors, cap in series, DC and AC on one node.
HPF is made with the input cap + simply added 39Mohm resistor to ground.
I'm not a fan of messing with anything on the input  at high impedances (also pad and hpf in u87 style).

Click to expand...

It's often done that way, although it increases distortion and noise; apparently, it's not a big issue for many users and designers...

MXL does this too. (Terminate the capsule with a relative low value resistor as a 'high pass filter'.)
The low frequencies are reduced, but the noise is increased!

Hello, please tell me: does the headbasket “split” in 2 pieces? I wanted to access the inside mesh/capsule but cannot find a way (no screws)

You asked me about that via email and i respond to you - check your "spam" if you didn't received email.

ln76d said:

You asked me about that via email and i respond to you - check your "spam" if you didn't received email.

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Thanks but I never received it, or went to spam and it's too late now

Anyway I've managed to detach the basket; i'm now trying to mod the circuit -- removing the HPF + the other mod you  mentioned for less voltage would be great. Can you share more info on that please?

I have electronic engineering background, but never actually modded a Mic circuit before.

Sorry for OT, does anyone know where to get TSB-2555 capsules in Europe?

Thanks, Anders

ln76d said:

Yeah, why not? Different sensitivity - electrode is electrode - slightly different material but can be polarised externally

Click to expand...

Do you mean you add external bias to increase the effective bias voltage? I understand it increases sensitivity and diaphragm tension. When is it useful?

Piotr,
What do you experience when you apply aditional polarization? Is it change in sound, or sensitivity/noise thing? If so, what kind of tonal change?

Does polarity of capsule matter when applying aditional BV?

I am so tempted to do it with c3000b capsule, even though i love the sound of it. Unique, but great.

By the way, your mod for GT55(md1bfet) works like a charm with Sterling Audio ST51!

Sredna said:

Sorry for OT, does anyone know where to get TSB-2555 capsules in Europe?

Thanks, Anders

Click to expand...

Some time ago i ordered them from china, but the source dried. Don't know any source in Europe.  If you will find it, please let us know.

abbey road d enfer said:

Do you mean you add external bias to increase the effective bias voltage? I understand it increases sensitivity and diaphragm tension.

Click to expand...

No, this is what Blue did. I added switchable option to use it as standard electret.

abbey road d enfer said:

When is it useful?

Click to expand...

For this you need to ask Blue.

I can only speculate it was made for two reasons - noise specs on a paper looks better, response of microphone is boosted in HF range.
Without extra polarisation voltage microphone sounds more neutral/flat.

kingkorg said:

Piotr,
What do you experience when you apply aditional polarization? Is it change in sound, or sensitivity/noise thing? If so, what kind of tonal change?

Does polarity of capsule matter when applying aditional BV?

I am so tempted to do it with c3000b capsule, even though i love the sound of it. Unique, but great.

By the way, your mod for GT55(md1bfet) works like a charm with Sterling Audio ST51!

Click to expand...

Depend on capsule, polarisation voltage range and the circuit.

It change sound - higher voltage -> higher tension -> less LF -> more HF
Sensitivity increased -> better noise specs (on a paper - you will not hear the difference) -> less headroom!
Usual better to polarise backplate.

Rather don't suggest to apply voltage into C3000B you will go back to original response with decreased headroom.
Look for other things in the circuit

I'm really glad that you like it

ln76d said:

No, this is what Blue did. I added switchable option to use it as standard electret.
For this you need to ask Blue.

I can only speculate it was made for two reasons - noise specs on a paper looks better, response of microphone is boosted in HF range.
Without extra polarisation voltage microphone sounds more neutral/flat.

Click to expand...

If I wanted to remove the extra polarisation voltage in this circuit (forever, don't need switch), whats the most simple way to do it?

Thank you and sorry to bother with noob sh*t

prismv said:

If I wanted to remove the extra polarisation voltage in this circuit (forever, don't need switch), whats the most simple way to do it?

Thank you and sorry to bother with noob sh*t

Click to expand...

Sorry i forgot to answer your last email.

On my FB site you have pic of modified mic. You can see there what need to be removed  and how the capsule is connected. Black wire from the cpasule just put to ground and that's it.

So you basically remove R2 (1Gohm) and C1, and connect red wire between the Transistor and 1Gohm R3, correct? 

With this mod I can't apply 48v Phantom right? Just use it as a dynamic?

I might also upgrade the other condensers, if you care to share the brands. Can't really see the button connections to proceed with the rest of the mod.

Thank you so much.

EDIT: I see now, you are using the switch as ON/OFF for the White wire. When "focus" is off you use external voltage, I assume. I don't get why you connect the last 2 pins of the on/off switch tho?

Yes, as you can see on the pic.
It's electret not dynamic
I don't have this microphone anymore, so i don't remember all the wiring.
Anyway it is simple, so you should be able to figure out.
You need just to make switchable connection between black wire from the capsule and voltage node or ground node.