Hi Len, The test has up until now been entirely focused on the B-Formats.
We are now talking about equivalent input noise, to determine whether your assertion regarding preamp gain affecting the performance of Tetra and Octomics was correct. I am assuming this is one of the ‘errors’ you refuse to clearly outline. We ran a second recording test at a higher gain level, which would appear to improve the noise performance, although the microphone’s self noise still dominates, as expected. It turns out the Zoom F8s preamps do get noisier below 40dB, by a very small amount as shown here: -------------- next part -------------- A non-text attachment was scrubbed... Name: image0.jpeg Type: image/jpeg Size: 290137 bytes Desc: not available URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20231105/40c2b87c/attachment.jpeg> -------------- next part -------------- If we had made our test recordings at 15dB gain, the degradation would be audible, but thankfully we chose 38dB. 2dB below the linear range threshold. Now that we are talking about the equivalent input noise of preamps, at your insistence, the performance of a single capsule is absolutely relevant. Perhaps not for any of the other microphones in the test but since you have made assertions about your microphones not performing well with the F8 recorder, it’s extremely important that I address your concerns to avoid others doubting the usefulness of the study. One of your concerns appeared to be not recording at a high enough gain, due to the low sensitivity (-43dB) of the capsules you use and the noise performance of the F8 at certain gain settings. Your proposed solution is to use a $4000 preamp, which is perhaps not accessible to all and certainly not practical for field recording, which is where the majority of ambisonic microphones are used currently. Your other concern regarding your non-use of a particular Transound capsule (sold as JLI-120A-T -43dB) has been addressed and the PDF has been updated. The specs and appearance are remarkably similar to the capsules you use, so I’m sure you can understand how this error could have been made. If you could outline any other errors you think we may have made that would be greatly appreciated. Thanks. Jack Sent from my iPhone > On 4 Nov 2023, at 23:31, lenmoskow...@optonline.net wrote: > Ambisonic microphones are always used as complete arrays and in B-format, so > that's the way they should be tested. Test results from single capsules are > irrelevant and misleading. > > Single capsule testing doesn't include what the the A- to B-format encoder > modifies. Some encoders do very creative things. > > So testing and evaluation should be done at B-format. > > > Len Moskowitz (mosko...@core-sound.com) > Core Sound LLC > www.core-sound.com > Home of OctoMic and TetraMic > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit > account or options, view archives and so on. _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
