That one with the LM317 sounds interesting… I’m already starting to cook something in my mind using those schematics and the phantom power example on the SSM2019 datasheet… I think the most expensive components there would probably be the capacitors (if I want to get decent ones), but maybe I should start a new thread to discuss that
In other news… I was playing around with gnome wave cleaner and I liked its noise removal. I didn’t know this app but I think it performs pretty well. The gui has some bugs but it’s usable.
It seems overkill to me, and I don’t see how they’re getting rid of rapid charge and discharge. Although that circuit would do it. Initially, I couldn’t see where they were getting enough DC to run everything, the monolithic regulator needs at least three volts across it to work, then I saw they were using two power supplies one + and one -.
But they’re both half-wave rectifiers. Wouldn’t you get better and stiffer raw DC with bridges or full wave? Then you might not need lab grade regulation or such large caps.
I didn’t look up the international spec on 48v phantom. I’m pretty sure there is one. It’s scary that people are not just using the juice to run a small amplifier inside a microphone. I have a new microphone that has three LEDs on the case as well as direction management and filter generation. Given all that, I’m sure they regulate inside the case. They were firm that they couldn’t do all those jobs on less than 48v.
I’m still not sure what I’ll use for source of power… I might go for a DC-DC converter. I have plenty of old power supplies ranging from 5V to 12V (DC) so I might use one of those and just make the voltage conversion to 48V plus some caps for filtering…
I can also try to use the 5V or 12V from the PC’s power supply, or even the USB’s 5V…
If I had a dollar for every time I’ve seen (or heard) a microphone being plugged in or unplugged with the phantom power on and the gain turned up on the desk I’d be moderately wealthy. Equipment needs, whenever possible, to be designed to withstand such abuse. The LM317 data sheet provides example schematics for how to protect the PSU from damage due to output short circuit. It also gives an example for a “soft start” regulator.
Trying to make my shopping list for farnell… Capacitors are probably going to be the most expensive components…
Farnell has many Nichicon’s but no FGs or KGs… For 63V rated caps they have Nichicon TVX series… dunno if they’re any good. I’ll probably go for the Panasonic FCs which they have, but only sell in packs of 5 units minimum…
Not all of the capacitors are “critical” though it’s unlikely to do harm to user over-specified parts (other than harm to the wallet). Capacitors in-line with the signal path (for de-coupling DC) are probably the most critical. Hopefully the microphone itself will have a reasonable degree of immunity to noise on the supply line and a regulated supply should be pretty quiet without using expensive capacitors, but if you have a capacitor across the power supply output I’d use a good one there.
Farnell have a second on-line outlet called CPC. They carry much of the same stock but have a different pricing structure so to compare one with the other you need to factor in shipping and handling charges.
As an aside, I’ve just about finished the new version of the noise gate - ended up rewriting it from scratch. The actual processing is very similar to the original but with a few refinements. It automatically applies a gentle (first order) high pass filter at 20Hz which takes care of DC off-set and it now follows the absolute amplitude (positive and negative) whereas the first version only looked at the positive part of the waveform. I’ve also tweaked the “cross-over” for a smoother response when frequency dependent gating is used and I’ve added a feature for measuring the noise floor though this last feature still needs a bit of work.
I think CPC only ships to the UK… I’m in Portugal, so no good for me
For the two DC de-coupling caps I’ll surely use the panasonics. For the power supply part I might buy something else… The panasonic FCs are not that expensive, main problem is that farnell only lets me order a minimum of 5 units of each capacity… I might also check local stores to see if they got any…
I was reading more thoroughly one of the reviews of my sound board and I just found out that almost all caps on it are Nichicon FGs, except for a few Sanyo OS-CON on the power connector. It’s a pity farnell doesn’t have the FGs.
I’ve been searching CPC for some of the components I need to buy and the price difference is marginal… Since I already have an account at farnell and I know they will ship to portugal without getting into more trouble I think I’ll stick to it… but thanks anyway for your suggestion Steve, appreciated!
While I don’t build my own preamp (which might take a while… like all DIY projects) I’m seriously thinking about getting the Art USB Dual Pre
While this will probably be redundant for you bgravato when you get your new pre-amp, I’ve finished the new version of the Noise Gate.
@ Koz, since you have experience with noise gates I’d be particularly interested in how you get on with this one - it’s even got a gizmo for measuring the noise level noisegate_v2-1.ny.zip (2.83 KB)
I was doing some more tests today… and I must give kudos to Steve… I tried different positions and distances for the mic, but at the end it was the 30cm in front of 12th fret that seemed to give a more balanced and less bass boomy kind of sound…
Tomorrow I shall receive the Art amp and I’ll post some samples once I get my hands on it
I only had half hour to play with it and I probably won’t have much time till sunday to get back to it, but here is the first sample recorded on linux: 31-art-usb-dual-pre-sample1.flac
I’ll post some more when I have more time… Still need to try it on the mac, but should work fine too.
So what’s that - 200% over budget? Oops - but not a penny wasted
Very nice indeed. If I was going to be hyper critical, you may need a new chair - is that sound at 31.7 seconds a wooden chair creaking?
Pretty late here too (I think we’re in the same timezone) and I should be sleeping 'cause I have a wedding tomorrow morning (it’s not mine no worries ), but I guess I’m still too excited about the ART to be able to sleep
Not sure what the cracking sound might be… surely not a wooden chair, because the one I was sitting on is made of metal and plastic and it’s new… Maybe it was the foot rest, which is also metallic but quite old so might produce some cracking noises… I didn’t even notice that sound until you mentioned it… I must be careful now… looks like this mic capture everything! (I hope I didn’t fart )
Your sample is in stereo and it sounds a bit like large room echo kind of sound… may I ask how you did it?
I’ve found a nice spot in my appartment where I can get a similar large hall echo effect “naturally”. I’ll try to record something there whenever I get a chance.
As for the budget… yeah like 250% over the initial expectations hehe but I think it was worth it.
One thing I’ve learn through time… if you get the cheapest… you’ll probably regret and end up getting the better one (did happen with the micplug). Also getting the most expensive doesn’t mean you’re getting the best one or, at least, not by a wide margin… I think the trick is always in trying to find that sweet spot between cost and quality… before entering the range where you need to pay 3 times more to get 5% more quality and above the range where you feel “damn this is crappy what a waste of money, I need better”.
Soon I’ll update the first post in this thread with my findings, conclusions and advices to those who might come next… and save them some work
), but I guess I’m still too excited about the ART to be able to sleep