Mini Studiomaster Mixer

 Posted by on June 7, 2008  Add comments
Jun 072008
 

re: Scott Walker. If you were familiar with those pieces of his work, you would understand
Just amazing lyrics, songwriting and the composition is amazing


I carried out some subjective experiments with my mini studiomaster mixer the other night.
After sending my line level out from Emu to mixer with all gains maxed on mixer the level was still lower than when it left Emu
This is because of the signal loss of the unbalanced RCAs I was telling you about
Also it seemed to lose some of the bass. Now this could be due to the fact that analog signals have a cut off point at 20hz where digital go lower than this. However, when i put a hi-pass on both of the tracks(before and after) there was still a difference in tone
Could also be to do with needing new capacitors
What do you think?
Paul

  6 Responses to “Mini Studiomaster Mixer”

  1. Hi Paul
    Check out what I mean by meter weighting as it means two different things….!
    One is for an actual physical meter and refers to the actual mass and return spring combination of the actual needle that jiggles. i.e. heavy needle = heavy weight so slow to react; heavy spring=needle returns to LHS stop quickly (and vice-versa etc)
    Two is the sound weighting applied to a frequency sensitive detector. This was done to try and model the human ear equal loudness curves because the ears are very sensitive at about 1-3kHz and the faint rustling 10kHz frequencies – that’s evolution for you. You’ll see phrases like “using the A-weighted curve” in various audio blurbs. Well they did this to sound level meters as well. So it means that -3db of steady 1kHz tone appears the same on all meters but as soon as you start doing music through them, they read differently.

    Modern software models all this for you and like I said, I’ve seen (Audacity I think, possibly) places in software where you can choose your type of meter and weighting curve to apply to it.

    Definate triple zeds now matey.
    zzz

  2. Hey man, as of the sound becoming quite thin across all frequencies, I was referring to a track that is out of phase and NOT the mixer.

  3. Hi Paul
    I thought you meant it was thin after it’d been through the little mixer. So you meant it goes thin if you’ve got two channels out of phase with each other. If so, that’d do that.
    It’s pretty hard describing this stuff in words. It doesn’t help if I don’t read the question properly coz that’s got us all of a tither. I’ll go back and amend comment #1.

    Then I’m off to bed. I’ve just put a picture up from the Alice dog show. Check it out. It’s all wrong man, all wrong.

  4. Woops sorry Paul.
    I set off on the wrong track there – I should have read your words closer on the high pass bit, what a twit. My brain flipped..
    Looking at all you’ve said, it looks like it’s just trimming a bit too much off the top and bottom of the audio spectrum or there’s some sort of presence-like peak inbuilt either by design or accident. That could explain your two (conflicting) statements of: “the sound becomes quite thin across all frequencies” and “with (…) digital (…) definite separation (…) whereas (…) mixer had more togetherness (…) a shit load better
    To my ears thin is a bit like separate and together suggests mushiness. But I sort-of know what you’re getting at despite that.
    For the levels thing, there’s a whole science devoted to the art of level control and meters. I haven’t checked in Reaper but I’ve seen in some of the programs you can decide what sort of meter you want and the weighting that it’s working off. It’s probably in this area that the discrepancy lies. There’s more to it than just peak, average, VU, S, etc etc They are designed for specific purposes (the BBC S-meter was initially to make sure the transmitter didn’t blow!) Tape meters did it another way etc. That’s the “art” behind getting to know your equipment. Some can go up to +10db others distort at >0db. Some is like “don’t let it drop below -3db”.
    I have found some info on your mixer though. Not very good I know, but it’s on the equipment checklist of an Indiana organisation called “Whitewater Community Television” – perhaps you could drop them a line to see if they’ve got an old manual lying around. http://wctv.info/forms/EForm.pdf
    Read the blurb. It’s a station set up for the residents of Wayne County! The Wayne County I knew had his nuts chopped off and is now Jayne County. He had the best title (and worst actual music) for a song ever:
    “If You Don’t Want to Fuck me Baby, then Baby, Fuck off”. That’s a YouTube link. Probably not a bit like Scott Walker. ๐Ÿ˜‰

  5. Hey man, a hi-pass does exactly that. It lets all high frequencies through at the selected frequency. So if you set it to 120hz, then everything below that is attenuated by way of whatever slope it is. I have tried to take some pictures with my phone and camera, but at such close proximity the pics are just blurred and further away you cant tell what it is. The mixer is a Studiomaster compact 4-2(they call it a mini mixer). I couldnt seem to find any info on the web at all. All checks were done with headphones and a spectrum analyzer. I could see the difference between the unprocessed track with the processed track. There was more level on the unrpocessed track in the bass region. Say 10kz to about 60hz. the one thing that I didnt try doing was swapping the channels, which I will later. Usually though the sound becomes quite thin across all frequencies when this happens from what Ive noticed. I will however check it.
    As of the levels being different, I matched them pretty accurately on the output meters of Reaper. The only problem was is you could match the peak, but not the avereage or match the average but not the peak. The mixer was definetely changing the transients or average. Not sure how though. Another thing, with the digital mix there was definite serperation between the individual sounds, whereas the mix processed through mixer had more togetherness(as a whole). Lets put it this way, it sounded a shit load better.
    As of all the technical stuff, still not quite there yet. I have ordered the Art of Electronics from the library though and am trying to get hold of a copy of Getting started in Electronibs by Forrest Mimms. There just doesnt seem to be an Audio electronics book for dummies book out there. Yet. Still looking for more info though. Have purchased a couple of books and understand quite a bit, but its just the basic parts and calculations
    There have been no mods made to this mixer. It seems like its never been used. None of the cpacitors are swollen or anything. I understand the whole theory of decoupling, but wouldnt know where to look though.
    I have however been giving a lot of thought o what I want to build, but we’ll leave that for another thread
    Me

  6. Hi Paul.
    It’s a pity I can’t have a look at it somehow – the mixer, that is.
    It’s a funny old thing this connecting equipment together lark. Usually it’s straightforward. Sometimes just just add a bit of gain or stick a bit of padding in to drop the levels to prevent clipping in the chain. Anyway, just thinking aloud while waiting for further info….

    The thing about the bass @20Hz is that you can’t really hear that sort of sound – you feel it, and it’s a very rare sound system that puts it out (headphones excluded) no matter what it says on the back…
    Whatever, when you say you’ve put a high pass on your tracks, I suppose you mean to strip out all the high freq and just listen to the bass end, somewhat muffled and all eh? And then when you put it through this (cheap?) mixer, it’s not as bass-y, yes?
    How did you do this, on phones or through your speakers or with a frequency analysis thingy?
    If you perceived the bass drop with your body then it’s a high bass cut-off, if you perceived it with your ears then it’s even higher, say 120Hz plus. If you’ve used a spectrum analyser you should be able to see the frequency effects on the screen and give answers more complex than you first thought!
    Also, if it’s an acoustic test, if the overall drops 6dB and you don’t match levels on the test, you will perceive less bass due to the “loudness” effect i.e. our ears aren’t “flat” and they are even less flat for changes in volume. See http://en.wikipedia.org/wiki/Equal-loudness_contour and https://www.phys.unsw.edu.au/jw/hearing.html

    Have you checked the phase of your stereo signal? It may be that you’ve mixed a stereo into mono and the phasing has cancelled the bass as it’s the first to go?

    If it’s a dodgy contact, dry joint etc, the top end goes first.

    You’ve already mentioned a capacitor. Usually, the low end roll-off comes from the “decoupling” capacitor. It’s called this so that it “decouples” each amplification stage from it’s neighbours. It obviously doesn’t decouple everything – as the sound wouldn’t pass! It just blocks DC and a few Hz up from that. It’s purpose is so that the correct DC bias is applied to each amplification stage correctly which governs the voltage “swing” that each transistor can make to a maximum before the high & low rails are hit and clipping kicks in.
    A side effect is to stop big voltage surges going through the stages (like at switch on or when to stick an instrument in – or out). This can seriously damage later stages and your speakers.
    Anyway, the high-pass rollover freq of this part of the input is a combination of this capacitor and the input resistor. It could be that one or both or the solder joints are iffy. Replace them all if necessary, they’re not expensive.

    One other point though. Is the overall gain down as well as the bottom end? Yes, it is, you said. Really it’s nothing to worry about. 6dB or whatever is nothing to make up. If I knew what the mixer was and it’s age it’d be easier. But it just looks like a manifestation of the different standards that have come over the years. One man’s Line Level isn’t the same as another’s unless it actually states on the packet that it’s working to the international line standard.

    One other, other point ๐Ÿ˜‰
    If this an old mixer, it could be that someone has previously “customised” it to their particular set-up. They might have had super-duper high-output pre-amps so to increase electrical flexibility and instead of using padding externally, they may have hard wired dropper resistors behind their input terminals. This would give the effect you’re experiencing.

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