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hapakid
Luna Ho`omalu
USA
1533 Posts |
 Posted - 02/21/2005 : 07:25:02 AM
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On impulse, I bought a Presonus TubePre preamp at Guitar Center for $99. I wanted it to boost vocals and passive instrument pickups before going into a little mixer and into my laptop for home recording. It's a small box and has a single 12AX7 tube, which is a standard tube for many amps.
Overall, I like it a lot. I put down a couple songs last night and the vocals jump out in front of the instruments better with the preamp. When I would plug in a mic directly before, I had to almost max out the gain and volume on my little mixer in order to get enough into the software. Now I run the gain and volume at moderate levels and it still sounds nice.
I'm looking forward to trying it with more instruments and different microphones.
On the downside, it seems to introduce a slight hiss, depending on the gain level selected. Maybe it's normal for a tube preamp, maybe it's from some other source or maybe I got a bad unit, I don't know.
But it makes my cheap selection of mics sound better.
http://www.musiciansfriend.com/srs7/g=home/search/detail/base_pid/184125/
Jesse Tinsley
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kihoalukid
Lokahi
USA
289 Posts |
Posted - 02/21/2005 : 07:57:37 AM
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| Watchout Jesse, it all starts innocently enough with your little 1 tube wonder, pretty soon it'll be a Marshall stack and you'll be playin Ledward Zeppelin,ya know, Whole Lotta Lilikoi, Stairway to Hana,etc... |
Lee |
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/21/2005 : 09:15:31 AM
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Jesse,
Tube preamps, especially modestly priced ones, will tend to be a little noisier than most (but not all!) modern solid state preamps. Tubes are high impedance devices (at the input) and Mics are low impedance devices. (Why?... Well... that is another subject) High impedance devices have low current-noise levels but high voltage-noise levels (there is always a trade-off between these two kinds of electronic noises). The best tube preamps will use super-high-quality input transformers to match the low impedance of the Mic with the grid (input) impedance of the tube. Such transformers are expensive (hundreds of dollars), but they have a great advantage in that they can create noise-free voltage gain if their output is connected to a high-impedance device (like a tube). This will let the tube run with lower gain and thereby result in much less overall noise. Tube preamps also create a little bit of a pleasant form of (even order) distortion which adds some "warmth" to the sound, and this often works well in the mix.
I used to design these things when I was a "kid" and still have some really-really good transformers out in the garage somewhere. But these days I would design using a FET rather than a tube (FETs are also high impedance input devices).
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
Edited by - Lawrence on 02/21/2005 09:19:38 AM |
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hapakid
Luna Ho`omalu
USA
1533 Posts |
Posted - 02/21/2005 : 12:38:14 PM
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Mahalo for the explanation, Lawrence! I think...
I did wonder what the definition of "warmth" was in relation to tube amp circuits.
Any recommendations for a reasonably-priced solid state single-channel desktop preamp?
Jesse Tinsley |
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/21/2005 : 3:43:09 PM
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Depends upon what you call "reasonably priced".
The unit that Ilio Nui has (Grace 201) is pretty good.
However, if you do not already have a small mixer, about the best thing you can do is buy a Mackie 1202 or 1402 (VLZ Pro). The preamps in these units are as good as the Grace (and petty much anything else on the market) but you get more of them for less money and you also get a mixer to boot. To make maximum advantage of these (or any other) good preamp you would need to take the channel direct outputs and feed them into a GOOD digitizer (NOT A SOUNDBLASTER or anything else from Creative Labs). Something like an Echo Gina or Darla or something from MOTU (Mark Of The Unicorn).
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
Edited by - Lawrence on 02/21/2005 3:43:24 PM |
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hapakid
Luna Ho`omalu
USA
1533 Posts |
Posted - 02/21/2005 : 4:17:44 PM
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Thanks again, Lawrence.
I'm using SM58 clone mikes into a Mackie DFX-6 mixer then into the audio-in port of my G4 Mac laptop. I thought the preamps in my little mixer would be adequate, which they are, but they don't add much oomph (not sure how to describe it.) Using a preamp makes the signal sound boomier, more live, and with more presence. I'm not sure what makes it that way, because if I did, I would understand what Lawrence and Big Dog were talking about on these topics.
I may take advantage of Guitar Center's return policy and see if I can't get something quieter.
Jesse Tinsley |
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/21/2005 : 5:55:08 PM
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Jesse,
I just checked the specs on your Mackie DFX-6, and you would have done better to get a 1202 or 1402 VLZ Pro, not that you did too badly. The preamps in your mixer have a EIN (equivalent input noise) of -127 db whilst the better preamps have EIN of -129.5db (with 150 ohm input - the input resistance matters a great deal, some folks cheat by listing specs with the lowest possible resistance which makes the numbers look better). A VERY careful listener can hear this difference (2.5db) under ideal circumstances. This means your Mackie DFX-6 is a wee-bit noisier than the best Mackie, but it is probably quieter than the tube units.
I mis-spoke about needing a 1202 however, cause if you get the Echo Gina3G you also get some pretty good preamps too, so you do not need the extra ones.
I suspect that the audio-in on you MAC is acceptable but not great.
However, you are obviously MAC-centric so the best equipment for you situation would be a little different.
You mention "boomier" sounds from the Mackie as opposed to the preamps. Hmmm... This sounds (pun intended), providing everything else is the same, (like the room, the micing distance and position, etc) like a microphone LOADNG difference. This is a little complicated, but has to do with impedance matching, which normally is not much of a issue these days in audio (except for microphones).
To simplify a little, some microphones are designed to be "loaded" with a particular impedance (resistance). This is kind of like a car that is designed to perform best with a certian weight. Too little and the thing is too springy and harsh, too much and the thing is swaying around and bottoming-out. The load presented to your microphones will be different between the two preamps, and so there will be a little difference in the sound (Dynamic mics are more sensitive this way because they do not have built-in amps/buffers - (condenser mics do)). As an illustration, me and some other audio engineers, back in the seventies, were able to get a better sound out of the Shure 545 microphone (relatively cheap) than the SM57 (more money), by running them into a higher impedance input (running them unloaded). The difference was amazing, and several professional releases were made this way.
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
Edited by - Lawrence on 02/21/2005 6:17:03 PM |
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hapakid
Luna Ho`omalu
USA
1533 Posts |
Posted - 02/21/2005 : 8:23:23 PM
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Thanks for the mike explanation. That clears up some foggy notions I had about mics. I still have a lot to learn.
My Mackie DFX-6 was $100 at a pawn shop. I like it because it has built-in effects for playing gigs, which I do about every six months or year. I had bought a Nady mini-mixer for the same purpose, but the digital delay effect sounded cheesy.
I have a couple of $20 SM58 clones and a $50 SM81 (condenser) clone. My laptop was issued to me by my employer, so I'm into basement recording for under a couple hundred bucks plus blank CDs whenever I want to inflict my music on friends. The preamp, representing a 50 percent increase in investment, was headed back to the store until I saw what a really good preamp cost. The Grace 201 is only about $1900. Ouch. I know why high-end studios buy names like Avalon and Grace.
Since I do this just for fun, big expenditures are not in the budget. But I've learned a lot from these discussions. After hearing Lawrence's work on the Kahumoku Workshop CD recordings, I must say that his kung fu is the best.
Jesse Tinsley |
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Reid
Ha`aha`a
Andorra
1526 Posts |
Posted - 02/22/2005 : 10:45:15 AM
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Lawrence,
A question or two on connectivity and duplication of function:
I assume you feed 2 XLR outs (for the mixed signal from various mics and black boxes) from your mixer to 2 XLR ins on your Layla, right? Wrong?
If you have good preamps in your mixer and good preamps in your Layla, which do you use? Both, at some level? The mixer's alone? I know that Echo products have some gain at minimum trim, so you don't have any choice about that, but which does the bulk of the preamplification?
Both mixer and Layla supply 48V phantom power, right? Which do you use for your mics? The mixer's?
still confused...
...Reid
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/22/2005 : 11:24:27 AM
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Reid,
My (older) Layla does NOT have any preamps. I use the direct-outs from the first eight channels of my Mackie to feed the eight line level inputs of the Layla. This is done with TRS balanced cables at a +4dbu level. This is one reason I got the Layla, because it supported fully professional levels with balanced lines in and out.
With the new Layla I would have to give up two line inputs, because the first two channels do not appear to have optional line inputs.
I do not actually do much mixing with the mixer, it serves as a preamp box, monitor control and I/O cross-connect, but it's MY party and I can MIX if I want to. Also I can drag the mixer out to gigs and such. And of course, the mixer yields the phantom, but only when I wear a mask and do "condensed" opera. 
Now I will start the discussion on how to use oxygen-free copper litz wire.... 
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
Edited by - Lawrence on 02/22/2005 11:25:42 AM |
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Mark
Ha`aha`a
USA
1628 Posts |
Posted - 02/22/2005 : 3:38:47 PM
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Hey Jesse -
I'd vote for keeping the Presonus pre. You can learn to control the hiss, and the extra warmth (OK distortion, But good distortion) coupled with the slight amount of "tube compression" you get should make up for any slight amount of hiss.
B'sides, with the mics you are using, plus the other, um, low end stuff (no offence meant -- just that a $20 SM58 clone can't really deliver the goods. Heck, neither can a real 58...), I'd guess you need a little extra whomp.
If you have a pick-up in your guitar, try using the pre as a direct box when you play live, too. Should really improve things.
The trick with all tube preamps is to dial in enough "warmth" without overdoing it. Back off until the tube's in the flow but you don't hear the hiss.
quote:
But it makes my cheap selection of mics sound better.
The bottom line is: if it sounds good, it is good.
cheers,
Mark |
Edited by - Mark on 02/22/2005 3:42:04 PM |
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/22/2005 : 4:03:35 PM
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One thing to add to what Mark said.
The Presonus seems to be popular among a lot of acoustic guitarists to use between their Guitar pickup and an Amp or for a "direct box". That extra knob on the unit that dials-up the distortion (tube drive) will come in handy in such a circumstance.
Yes, and some Mics with higher output will allow you to turn down the gain and get less noise.
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
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hapakid
Luna Ho`omalu
USA
1533 Posts |
Posted - 02/22/2005 : 4:14:44 PM
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Thanks, Mark and Lawrence. After looking at what is available in my cheapie price range, I decided to keep the Presonus and figure out how to work out some of the hiss.
Plus I want to try gigging with it. Heck, I'd just like to try gigging.
After listening to my first track through the tube amp, it struck me that it sounded like music we used to hear in the 1970s. Not because of the music, but the hiss recreated what music sounded like before the digital age. And I didn't mind it so much.
Jesse Tinsley |
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Mark
Ha`aha`a
USA
1628 Posts |
Posted - 02/24/2005 : 3:37:15 PM
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Ah, that lovely analog sound.
Ya know, Jesse, there are all kinds of effects you can buy that recreate the sound of tape saturation, tube compression -- and even surface noise from an LP so that your digital recordings sound like they came from tape or an LP.
Nuthin' like the real thing...
If you recall the early days of CDs, they usually had some sort of disclaimer to the effect of: "Because of the superior reproduction of the CD, flaws in the original analog recording may be audible."
When one of my LPs first came out on CD way back in the way back I wanted to include the following note: "This digital recording was remastered from an analog source. It will not sound nearly as good as it did on vinyl."
cheers,
Mark
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Lawrence
Ha`aha`a
USA
1597 Posts |
Posted - 02/24/2005 : 6:46:28 PM
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quote:
It will not sound nearly as good as it did on vinyl."
Hear..Hear... to that one. At the "peak" of the vinyl technology the frequency response exceed 80KHz! Now we are squashed down to a brick wall for CD's at 22.05KHz, and most aren't even that good. Fortunately, I can't hear past 20K anymore (but I can see it in the FFT!).
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Mahope Kākou...
...El Lorenzo de Ondas Sonoras |
Edited by - Lawrence on 02/25/2005 07:17:24 AM |
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hapakid
Luna Ho`omalu
USA
1533 Posts |
Posted - 02/25/2005 : 07:39:30 AM
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When I listen to my recordings made with the tube preamp, it sounds like I'm listening to a cassette, which is kind of eery.
Jesse Tinsley |
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