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Tube Comps?

Discussion in 'Pro Audio Equipment' started by eddies880, Dec 1, 2004.

  1. eddies880

    eddies880 Guest

    According to several post Ive read about using a tube compressor,it seems like the use of any other compressors is a waste of time and money.
    I plan on buying a tube compressor here shortly,but in the mean time,Im stuck using my Alesis 3630.
    Which tube comp should I look for ($500.00 range)--------and my next question---------------what do you think I can get away with (safely) when using the Alesis comp? :?
    And last but not least-----why do tube compressors sound better?
     
  2. Nathan_Eldred

    Nathan_Eldred Active Member

    My $.02 is that you shouldn't buy a tube comp in the $500 range. It's going to be a low voltage, low fidelity toy. Look into something like an RNC or maybe a DBX 160xt (I think that's the model number, a guy here in Orlando has a couple and they sounded decent on drums for the money). The RNC is basically a soft knee design, the DBX I'm pretty sure has a harder knee in general making it maybe a little better for percussion, where the RNC is going to better at things like vocals, acoustic guitars, etc...although both will be fine on just about anything if you know how to set it right. The problem is, is that there is a big gap in the market between something like the FMR RNC and specifically the Empirical Labs Distressor. If someone could come up with a single channel comp of truly pro quality in the $900 range it would do well.
     
  3. mikE@THECAVE

    mikE@THECAVE Guest

    use the RMS setting on the alesis and back off the ratio so it doest change the sound alot
     
  4. Massive Mastering

    Massive Mastering Well-Known Member

    There are bunches of nice SS comps out there... You don't "need" tubes to get a nice sound.

    That being said, I think everyone should have at least one Art Pro VLA. That's less than $500, and quite a nice, usable unit.
     
  5. anonymous

    anonymous Guests

    Ahhhh, yes... the advertising works

    Now there's the $64,000- question!!

    Tube compressors don't necessarily sound "better", in fact, there are a whole lot of 'um that don't even sound "good" never mind "better".

    There are a few different types of "tube" compressors, there are "remote shutoff" tube compressors [which is actually a real tube compressor as it actually uses the tube as the gain reduction element] and there are compressors with a different, non-tube gain reduction cell with a tube amplifier infront, and/or behind the gain reduction cell. Most often these gain reduction cells use the principle of optical attenuation, but I'm not going to get into that principle today.

    Now, a "remote shutoff" or "delta- MU" [or if you're into trademarks, "variable-MU"]... The way a remote shutoff/"Delta MU" limiter works [warning: seriously over simplified explanation to follow] is that the audio modulates the voltage to the grid of the tube. The control voltage on the grid controls the amplification factor of the tube [a.k.a "MU" of the tube], in a remote cutoff triode you have a much greater range of gain control because of the way the grid wire is wound... the spacing is non-uniform. In a sharp cutoff triode like a 12ax7 the spacing is wound uniformly and there comes a certain point where the flow of electrons is pinched off causing the tube to stop passing audio... in a good remote cutoff the tube never cuts off entirely...

    So, as the quantity of audio increases [stuff gets louder, more voltage] the current to the grid of the tube decreases, thus the output level of the amplifier decreases. When you employ a "Variable Gain Amplifier" [VGA] of this nature, it creates a situation where you do indeed have less dynamic range, the point and purpose of an audio compressor/limiter. The amplification a tube provides is called the "MU" of the tube, by changing the "MU" you change the gain, by changing the gain of the tube in a manner controlled by the actual audio, you control the dynamics of the signal.

    There are different tube types that can be applied for this task, some are triodes, some are pentodes. Generally, we find that triodes have a greater abundance of even order harmonics associated with their distortion characteristics so we find them "warm" and musically pleasing, however, some pentodes also fit into this category... in other words, the tube chosen for the circuit is an integral portion of the design of the circuit and will seriously affect the resultant tone of the equipment.

    One of the biggest questions when choosing a tube for this application is how smoothly the tube responds to the variations in plate voltage. With all triodes the wires on the grid are wound around two metal posts. With triodes like a 12ax7 the way the grid is wound is very uniform so you can actually get the tube to "turn off". With tubes that are really suited to a remote shutoff application [like a 6386 or a 6es8] you will find a very musical, fluid response to the way the tube handles the audio. The way the grid is wound on tubes that are well suited for a "delta MU" design is that the grid windings are fatter in the middle and narrower on the edges... which means that the electric field never cuts off the flow of electrons between plate and cathode... i.e. the sound doesn't totally cut off and you have a greater control range on the attenuation. The reason I mention this is because there are some "remote shutoff" units out there that employ a 12ax7 tube because they're in plentiful supply and rather inexpensive... the problem is that they don't do the job properly... but hey, they have the right buzzwords so who cares.

    So... if you've gotten this far without your eyes glazing over... let's just say that this kind of science and attention to detail doesn't happen in the $500- range. In fact, it doesn't happen in the $1000- range, you're looking at like $3,500 for a good quality two channel unit... or you're looking at getting suckered by one of the nice people who make the garbage you will find in your local Banjo Mart that says "toob" on the faceplate [or in the case of the real ^#$%ing garbage, has the "toob" showing through the faceplate].

    The more you know, the less they can snooker you... I hope this was of some assistance.
     
  6. JeffreyMajeau

    JeffreyMajeau Active Member

    And as far as the dbx units, I'm fairly certain that most of them are "soft knee". I know that some of them have a switchable knee, from dbx's "overeasy" to hard, but any of the 1/2 rack units, I'm pretty sure, don't.

    I have a pair of 163x's that are definitely soft knee. They certainly have a sound, too. Squash the $*^t outta whatever you put thru em. Great for the "spank" channel of paralell compression.
     
  7. afelluss

    afelluss Guest

    The problem I've run into with low end compressors (specifically dbx 163x and Alesis 3630) is a major degradation in signal quality. I've checked both of these by patching a mic pre into it, and then around it. The difference is not good, worth checking out if you have the time.
    I like Maprotulz' idea of using the dbx as a supplementary sound though.

    I love the TLA 100 for recording vocals, but it's a little pricey for me now. I'm interested in learning what's up with the TLA-50, halfrack deal... anyone checked it out?
     
  8. JeffreyMajeau

    JeffreyMajeau Active Member

    My dbx 163x's will absolutely beat the $*^t out of whatever you stick through them. Not subtle. I hardly ever use them.

    Any compressor will compress your dynamic range, but not all of them sound good while doing it.
     
  9. eddies880

    eddies880 Guest

    Looks like you have some knob turning expierence with the Alesis.
    How about some ideas comping guitars and vocals :cool:
     
  10. JeffreyMajeau

    JeffreyMajeau Active Member

    If you're using a DAW, I've gotten into using the automation to "manually" compress the vocals. Just write an automation pass of fader rides, or go draw them in. Sounds way cleaner than any hardware box or plugin and you can make it rock to the music.

    Once that's done, you should be able to go back and use a setting between 3:1-6:1 or so and get it to lop off about 6dB on the hottest parts - feed in an appropriate amount of makeup gain and it may get you part of the way there.

    This isn't a universal formula, though, ya gotta fool with it to get the sound you want. I hate overcompressed vox on most things, so I try not to beat it up too much.
     
  11. David French

    David French Well-Known Member

    I second that. Great lesson. :cool:
     
  12. eddies880

    eddies880 Guest

    got-it :cool:
     
  13. Big_D

    Big_D Well-Known Member

    Fletcher, Superb post!!! Now that's information I can really use. :cool:
     
  14. Screws

    Screws Active Member

    I use an Avalon 747 on the mix quite a bit. It's an opto comp with a tube amplifier circuit. Switching the tube into the signal path gives the mix a bit of sparkle and roundness that is great for certain things.

    I'd love to mess with an ES-8, though.
     
  15. mikE@THECAVE

    mikE@THECAVE Guest

    well i used it in the RMS auto mode that sets the attack and release for you then you have to pick the amount of ratio you want
     
  16. eddies880

    eddies880 Guest

    Thanks Mike :cool:
     

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