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Parallel capsules with simple p48
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Hi all,?
First post on here - I've done a search through the group but couldn't find a definitive answer. I've been mucking around lately with aom5024 capsules to go along with the clippy mics that I have, and have been quite happy with their performance. I've got some as PIP, and I've built some into XLR plugs using the simple p48 circuit to use with a zoom h5, and these also work a treat. I've seen a few mentions online about the merits of running two or more capsules in parallel, and would like to try this myself. Seems fairly straightforward with the PIP examples online, however I've been overthinking it in regards to the phantom power XLR connection and am now double guessing myself. My question is: 1) can I use the the same p48 circuit I used for a single capsule, and just wire two capsules in parallel 2) do I do #1 but adjust the cap/resistor values to accommodate the multiple capsules
3) does each capsule require its own resistor/cap? Thanks in advance guys :)? ?? |
开云体育Others will correct me if wrong, but based on what I've read here about this: With Simplest P48 (capsule + resistor + capacitor) you can indeed parallel the capsules. You use a single resistor/capacitor set, but you cut the resistor value in half for two capsules, to 1/3rd for three capsules, etc. You can apparently also parallel the entire SP48 circuit off the XLR, which someone suggested might be better for 3 or more capsules. My notes say "Could theoretically power ~14 in parallel, but CMRR
degrades with each capsule (because SP48 loads only one of the
6.81k resistors used in phantom); "in the real world you should be
OK putting three or four P48's in parallel" " Someone on this list (sorry for lack of attribution) also said "Doubling the number of capsules can improve your SNR by 1/sqrt(2). So going from 1->2 improves things by that much. Going from 2->4 does so again. Going from 4->8 does so again. But that's where things get a little iffy. 2 capsules arranged vertically mostly works because most sources are going to be in the plane of the mic so you won't get much in the way of comb filtering between the capsules. By the time you've crammed eight capsules into one spot, it's going to start having a noticeable effect. Also, if you look at what 1/sqrt(2) looks like in dB, it's tiny. It's about a 1.4dB improvement in SNR. I don't know how tight the tolerances are on the Primo or PUI capsules, but you may be able to better that by just picking the best of a batch and using those as single capsules per channel." There are other considerations, but that about sums it up. :-) -c On 2/13/25 15:31, Cram via groups.io
wrote:
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Thanks so much for the reply Casey - this is most helpful. I'd figured there shouldn't be any harm in doing #3 (apart from increased parts cost and space for components), but wanted to be sure there wasn't a better way of doing it. I'm at work right now so don't have my mics in front of me. From memory I had my single capsule p48 5024's running at around 5v and they sound quite good to me. I was thinking of pairing up two capsules per channel to try this out, though I do have enough to do three. Now you've given me some clarification I can do some experimenting.? Being an astrophotographer also, stacking data to increase SNR is something I'm familiar with, though it's interesting to note your assessment of the dB gain in this situation. Having been reading through Vicki Powys' website and a few others touting parallel capsules, including micbooster themselves, it's been suggested there's an approx.? 3dB increase to SNR and 6dB to sensitivity. In micboosters case it really does appear to be just 2 capsules in parallel like other tinkerers do online. I'll be interested to see the outcome with my mics.? ? Cheers!? |
Being an astrophotographer also, stacking data to increase SNR is something I'm familiar with, though it's interesting to note your assessment of the dB gain in this situation. Having been reading through Vicki Powys' website and a few others touting parallel capsules, including micbooster themselves, it's been suggested there's an approx.? 3dB increase to SNR and 6dB to sensitivity.Yeah other members here (Joules and Jerry Lee, not sure who I'm quoting here) have said "The concept is that the audio signal from the capsules is correlated and the def noise is not.? The math part says that adding two capsules gives you a 6dB increase in signal. But the noise only adds 3dB.? Real world is close." So that accords with your 3dB idea, but I'm not sure how to square that with the 1.4dB quote. Perhaps someone here can clarify. Some other quotes from my notes: "...one must consider the changes in directivity pattern. Depending on the physical arrangement (side by side, colinear, back-to-back...) the results may change significantly. The side-by-side arrangement is the one that gives the best improvement in S/N, but it also results in some narrowing of the pattern at HF, which may or may not be desirable." -c |
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开云体育Thanks! So you're saying the parallel capsule (case of two
capsules) does in fact increase SNR by 3dB (in ideal mathematical
conditions)? -c On 2/13/25 20:20, Jerry Lee Marcel via
groups.io wrote:
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开云体育It's true for sounds that are radiated in the pruimary
directivity lobe. Le 14/02/2025 à 05:41, Casey via
groups.io a écrit?:
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