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Hello, it´s me again.
I bought the revelator io24 a few weeks ago to substitute my Focusrite scarlett solo because I wanted an easy way to compress my headphone mix during recording. In the last two years I recorded many hours with my existing equipment so I know the sound fairly well. My microphone is a DIY Alice microphone (https://www.instructables.com/OPA-Based ... d-a-Figur/). When using the revelator I felt the sound of the mic was dull compared to my former equipment. The last weekend I compared the old and the new interface and found something interesting. To explain what I did: I recorded a phrase of a song 4 times with different configurations of 1 microphone, 1 mic preamp and 2 interfaces. I first used the microphone inputs of the interfaces. Then I used a mic preamp and the 1/4" jack of each interface. The only thing I changed in the setting was to adjust the input level of the interfaces so that I always recorded with the same headroom. To do this I used a testtone played on my phone I held 20 cm away from the mic. The sound files are completely unedited, no eq, no compressor and, as you may hear, no melodyne  I only normalized them to -1 dB. You can hear the difference in sound of the mic input (example C) and the instrument input (example A) of the revelator. The scarlett in comparison shows almost no difference between the inputs. Maybe someone has an explanation for me? I did not expect such a difference. Greetings, Michael.
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For this test to be accurate, you'll need to bypass the presets.
Did you do that?
PLEASE ADD YOUR SYSTEM SPECS TO YOUR SIGNATURE.
Download the SO 6 PDF MANUAL. Access your MY.PRESONUS account. OVERVIEW of how to get your issue fixed or the steps to create a SUPPORT TICKET. Needs to include: 1) Subject 2) Description 3) Country 4) Product 5) OS 6) Audio Software Windows 11 Pro 64-bit (23H2), Studio One 6.6 Professional | Notion 6.8.2 | Universal Control v4.2.0.96206 Intel NUC 13 (Intel i5-1340P, Intel Iris Xe Graphics, 32GB RAM, 2TB SSD, Revelator, SIII 32 |
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Hello Trucky,
yes, presets were bypassed and I checked that the fat channel was turned off. Thank you for your patience! Michael. |
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Maybe the io24 doesn't provide enough phantom power to fully power your mic? Does your mic need an upper limit amount of phantom power?
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Thats a good idea. But I have no clue how to measure this. And I dont know what the io24's power limit is. I know that it worked with another interface on the same USB port.
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A good comparison would be to measure DC voltage between pin 2 and pin 1 (and/or between pin 3 and pin 1) of the XLR cable, with the microphone plugged in. Simply open the male XLR plug before plugging it into the interface, exposing the contacts inside the plug. You should be able to remove the barrel completely. Don't short any metal bits together when phantom power is on! All wires are safe to the touch.
Ideally you would see a DC voltage of 48V (or at least 40V). Repeat the test after removing the microphone from the cable, and also with another condenser microphone if you have one. Test both interfaces. The results you get will show if phantom power is a likely suspect. If it's low on the io24 compared to the other interface then it may be because phantom power on the io24 is weak anyway or because the interface requires more power (from the USB port). |
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Hello SwitchBack,
I measured the DC Voltage. Without the mic I had about 47V which dropped to 20.1V when I plugged the mic in! I thought: this is it - until I tested the other interface (drops to 20.7V) and the mic preamp which has an external power supply. Even this one drops to 20.0V. This seems strange to me. I have no other condenser mic but I will try to borrow one and keep you updated. But it seems that the voltage is not the cause for the change in sound. Edit: The voltage is fine. According to the troubleshooting guide of the mic the voltages between pins 2/3 and pin 1 should be at 20.83V. Did you listen to my examples? Do you agree with me that ex.C sounds noticeably different or am I expecting too much? Michael. |
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Yes, C sounds muffled, as if anything fast or high frequency gets smothered. This can be a voltage level problem: fast changes draw extra on the power supply. When power supply is marginal then that's the first to suffer.
And that 20.83V will be with your mic plugged in. So all those inputs seem to struggle with it. |
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The mic is not a "real" condenser mic, it's an electret capsule. Internally, the mic uses a voltage divider to generate a virtual ground for an op amp. The voltage of around 20 V DC is perfectly fine. It is not because the mic draws so much power but because of the circuit that's inside the mic.
The best would be to make the test again with a condenser mic. But first I have to get one. Thanks. |
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Many condenser mics use electret capsules. The difference between electrets and condenser capsules that need external voltage is usually ignored because both need a preamp built into the microphone anyway. So from the outside both are condenser principle microphones that need phantom power. And keeping a capsule charged doesn't need power, just voltage.
But the preamp/impedance converter does need power and some designs need more than others. More power = more current = more voltage drop. So I'm curious what the voltage drop will be if you try your preamps with a simple AT/Rode/Samson pencil mic, or something like that. |
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Hello SwitchBack,
I thank you for your thoughts. I found someone to lend me his Rode NT2. I hope I find the time to do the test within the next few days. So I will do the same 2 test recordings and I will measure DC Voltage. I will keep you updated. Michael. |
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Hello Forum,
so I did the same test with the rode nt2. Good news: There is no big difference with the nt2 plugged into the revelator or with an additional mic preamp. As the rode is a true condenser mic (no electret capsule like mine) and therefore works in a different way I did not measure the DC voltage. Because I still wanted to know what the problem is I plotted a frequency analysis curve and found something interesting: The muffled recording (C) shows deep dips in the frequency curve above 4 kHz which the others don´t have. For those who are interested I added two plots. I have no explanation for this because now it gets weird: I did the same recording today to find out if I can reproduce this muffled sound. I even put the mic cable rolled to a coil directly on top of the power supply of my laptop. But the problem doesn´t occur anymore. So what do I learn from this: The revelator works as normal, my mic works as normal and there is an audible difference between the rode and the DIY-Alice mic. Which sounds better? Hard to say. Judge for yourselves if you want to. Thank for trying to help me although there is no real solution. Greetings! Michael.
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I still believe that's power related. Did you use the same USB cable for you io24, into the same computer USB port? USB voltage is only 5V so USB powered devices use charge pumps to boost voltages to required levels. If for some reason current from the USB port is insufficient (because of a poor cable or bad contact or because the USB port can't deliver enough mAmps) then charge pumps start to stutter (at a high frequency). That C-signal seems to dip every 4kHz which could indicate just that.
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Hello SwitchBack,
i thought about this too and therefore ordered a measuring device to see the current the revelator draws from the USB port and compare it to the scarlett and post the results. I already had issues with the USB ports: When I use the USB-2-ports then studio one gets very slow: the meter display freezes from time to time. So I only use the USB-3-ports. But according to the manual the io24 should work with USB-2, too. The presonus support told that the device is a USB-C-device whatever that means regarding the current. I think if it is advertized as both USB-3 and USB-2 compatible there should be no issues in this regard. |
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Hello forum,
I measured the voltage and the current with the Rode NT2 and my Alice-mic I with my high-end chinese measuring device. The voltage always stays at 5.07V, the current changes slightly: Revelator without phantom power on: 0.33 A Scarlett without phantom power on: 0.3 A Revelator with Rode NT2: 0.4 A Revelator with Alice: 0.44 A So it seems that all voltages and currents are well within the range of the USB 2 standard of max. 500 mA and I still have no idea what the reason for the muffled sound was. I think I don´t want to spend more time searching and hope the problem will never occur again. Thank you! Michael. |
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