substituting LD electret capsules for "standard" LD condensors in tube mics?

armstrom

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Mar 17, 2010
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I'm going to be building the a5500 tube mic kit from Aurycle soon and I've done quite a bit of research regarding possible upgrades. Swapping the tube is not an issue for me, however the alternative capsule of choice (the Peluso PK47) is almost twice the price of the kit itself! Is there any possiblity of modifying the circuit to work with one of the more popular (and much cheaper!) LD electret capsules like the TSB-2555A from transsound? The transsound capsule doesn't have a built-in jfet so it shouldn't require any modification, however I'm sure I'll have to remove the polarizing bias voltage. Beyond that, is there anything else that must be changed or should I just try it and see what happens? :)

-Matt
 

abbey road d enfer

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Yes, you would need to remove the capsule bias (R10) and connect the capsule directly to the grid. The capsule needs a DC path to ground in order to function.
But I sincerely doubt this would be a valid alternative. It is probably a worse choice than the original included capsule. The output level is significantly lower, so the noise figure will deteriorate and the max SPL of 120dB is a very mediocre figure (although I'm not sure it's accurate, since ALL their capsules exhibit the same SPL and S/N figures).
The capsule is the single most important factor in a condenser mic. A good capsule is expensive.
You can experiment with capacitors, tubes, transformers, you will have small changes in flavour, but nothing as significant as changing the capsule.
 
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