millenium pp2b mod
Those little handheld fieldrecorders like the sony pcm-d50 are fine but there are occasions where an external mike is more handy. Only, the pcm-d50 has no phantom power so a solution must be found.
Sony makes a very nice unit but it costs almost more then the recorder. You could use a battery powered mixer but that is also an expensive solution.
The sony preamp is actually not bad at all so only a power supply would be needed.
I could not resist to order a battery powered phantom power supply for 29 euro.
First thing I did was to take it apart.
Now, I like to keep my microphone lines balanced only to unbalance them with transformers close to the recorder.
There is plenty of place in the power supply to house two neutrik nte4 step-up transformers. They are very affordable, I payed less then 10 euro for one.
The mod is very easy, just bridge the output xlr with the transformer. I mounted a 3.5mm jack to connect the recorder. You can solder the trafo wires to the 100K resistors.
The finished result, now I can use any mike I want. Total cost less then 50 euro.
By the way, this also works as a splitter.
update
I explain in the comments why I used a 1:4 transformer and I made some measurements.
There is also a very good document on the Jensen site.
update
A better picture where to connect the transformers
update
Some more measurements.
Comments
But i wondering why you chose a
transformer with 1:4 step-ratio?
Would the neutrik nte 1 (1:1) not be a better match?
So why a step-up?
The idea is to take advantage of the 22K input impedance of the PCM-D50 to gain a few dB. The 1:4 ratio will lower that 22K to 1.38K which is still acceptable.
I did not measure the result but you gain 12dB in voltage from the 1:4 step-up and you loose something from the (16x)higher source impedance. That source impedance will be related to the mike.
What's your opinion on the matter, is there anything to gain from buying a more expensive unit for example Rolls pb224 or something even more expensive. The Millennium voltage is in the range of Phantom power standard 48v +/-4v, so that should be no problem, but are those more expensive ones more quiet because of better components.
I'm thinking of getting a unit to go between my Karma audio K-10 mics and Olympus ls-10. The mics have self noise of about 17db A-weighted, sensitivity of 14 mV/Pa and output impedance of less than 200 ohms.
Thanks for the interesting post!
Input of the LS10 is unbalanced so you will need the transformers for the best results.
If you are not a solder slinger you will need to find a transformer and a Y cable to connect the transformers to the LS10.
(hey, and that was the reason for the mod in the first place..)
I'm looking to pick up a couple of these for Ambisonic field recording. My Tascam DR680 has far too much phantom power noise at higher gain (the level I'm often recording at). Could you comment on their overall noise level if hitting the gain pretty high? I was considering the 2phant, but that price tag is a bit much. Perhaps I could swap out some of the "el-cheapo" components for better ones?
Thanks for your opinion
(Having trouble posting, apologies for double posting)
I used a battery powered NTG-2 with my recorder via a xlr to dual mono cable (pin 3 short to pin 1 and pin 2 to both tip and ring) and it worked well.
I'm wondering if shorting pin 1 and 3 on the output side of the pp2b won't damage the unit or the mic? From the schematic it looks like I'll be shorting the phantom?
Any thoughts? If that is ok then I'll probably try your mod.
Thank you for your reply. I boight the NTE-4 transformers and will be doing the mod. I have a question. I only have a transformer soldering gun. Can I use it to solder the transformers in? I've heard that they can demage electronics by electromagnetic, induction field etc. Any thoughts on that?
Can you tell me if the Millenion stops when the batteries are dead or does the current drops slowly with the batteries ? (That will be no good)
Thank you and best regards Aart
1. Does the signal on the xlr output becomes less by soldering in the neutrik?
2. If so can I simply put a on/off switch between the neutrik yellow input wire
3. Can I use the pp2b with neutrik as a standard interface between the xlr input and the camera to do a proper unbalancing.(I mean even when I do not need phantom) For example when I receive two lines xlr from the sound people in a theatre setup ?
Thank you for this very helpfull article.
With regard to question 3, the load of the phantom power circuit can usually be neglected. just switch off the power.
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