Simple Question

I think :slight_smile:

Hi Guys :)

I purchased a presonus tube preamp to improve the quality of my vocal recordings a little while back. However I realize that I am not clear on how i should use it in the signal chain. Do I try and totally bypass my mixer now so as not to pollute the hopefully cleaner and nicer signal of the presonus preamp ? Or do I run the rather hot outboard signal of the preamp into a channel on my mixer and watch the gain staging carefully ? Or something else all together ?

I would appreciate any help and when you answer feel free to assume I know nothing, this would be a safe assumption :)


Thanks To All,

Ted

I would say deonds on how clean your mixer is…
At teh same time there is nothing wrong with adding more colour by going through the mixer if it sounds good…

Also, depending on how many inputs you have on your soundcard it may eb easier to leave the presonus permanantly connected to one of your mixer channels than having to unplug and plug it back in all the time… This may come down to a trade off in convenience vs percieved difference in sound…

FWIW I have my ART DPS preamp permanently connected to 2 inputs on my soundcard with a behringer compressor in between.
Even if I’m not using the compressor I don’'t bother reconnecting the leads to bypass it… I don’t think there is a noticeable difference in sound to my ears…

Do we buy tubes to get cleaner sound? :)

Try both, but I’d just use the presonus right into the sound card, unless your mixer is something really nice.

Which presonus? I got the Eureka a couple of weeks ago. Man, is that a great box. :D

Hello Tom and Rich :D


I looked up the Eureka Tom, it looks like it gets great reviews, you obviously have a bigger budget than i do, hehe.
The preamp I bought is a Presonus TubePre, it is just a Pre with no compression or EQ. However I just got an incredible deal on two stereo compressor/limiters from Samson. So I guess I will hook mine up the way you and Rich are suggesting, which is ( see below )

Mike ----> Preamp ----> Compressor -----> Soundcard.

Is that what yall suggest ?

My mixer is not exactly top of the line ( its a behringer ) so I guess I’ll bypass it all together. I am using a Rode NT1a as my mike.

From what I understand I can also use the Presonus as a direct box for Bass and Guitars and run that like this ( see below )

Guitar/Bass ----> Preamp -----> Compressor —> Soundcard

Is that right ? This will actually make things simpler for me because the Presonus Pre and the Samson compressor are very easy to setup and I like simplicity :)

Thanks Guys for your time and attention,

Ted

You can use it directly into the soundcard but if you adjust the gains carefully you can probably run it through the mixer without losing the improvements you purchased it to achieve. Set the mixer input trims to minimum gain and adjust the preamp gain so that you are below clipping on the mixer and you should be OK unless your mixer is unusually bad.

The primary advantage of a tube preamp is the way it handles overloads and the nature of the distortion characteristics. These benefits are most significant at higher signal levels so you want to make sure that you clip in the preamp rather than the mixer. At the other end of the dynamic range the performance is typically determined by the noise performance of the very first stage of amplification (in this case the preamp or possibly the microphone itself). The reason for this can be easily understood by imagining two amplifiers with the same noise performance in series. If you think of the noise as appearing at the input of the amps (input-refered noise) you can see that the noise at the output is increased by the gain of the amp. If (for example) the first amp has a gain of 20 dB, then its output noise will be 20 dB greater than the input-refered noise of the second amplifier (for identically performing amps). The sum of both those noise sources is only a fraction of a dB greater than the noise contributed by the first stage alone. If the second amplifier has a noise that is 20 dB worse than the first (equal to the output noise of the first stage and an extreme case), the combined noise will only be 3dB greater than the contribution of the first stage into a noise-free second stage. It takes an awfully bad mixer preamp to generate those kinds of noise-levels so this is rarely a problem, even if you are not satisfied with the noise levels of the mixer when used alone.

The reason for running through the mixer would be to make it easier to set up a monitor mix.

Jim

Hi Jim Bob :D


Thanks for the thorough response. I have gotten so used to running my stuff thru my mixer, prior to owning the Preamp, that I was uncertain what would be the ideal setup given my new situation.

I appreciate your help,

Ted

The first outboard pre I ever bought was a Presonus Blue Tube. I was recording everything through a Mackie 1642 VLZ before that. When I got the BlueTube I tried recording vocals and acoustic guitar with the pre running into my Mackie vs. hooking the pre directly into my Delta 1010. Big difference in sound. The tracks sounded much better going directly into the card. The direct tracks had more depth, were more articulate, and had a fuller sound. I also compared the BlueTube to the Mackie pres and there was an even bigger difference in favor of the BlueTube.

Before that I thought my Mackie sounded pretty good. As soon as I realized the difference was so great between that cheap little BlueTube and my Mackie I started buying more outboard pres as my budget would allow. I now have two ART Pro Channels, another BlueTube (4 channels total) a Presonus MP20, Electro Harmonix 12AY7, and an ART MPA Gold. Everything is hooked directly into my Delta 1010 and Delta 66. I avoid the mixer completely now.

I believe you will find the same thing with your Behringer but you should try it and see.

It’s not just noise in the berry, jimbob, IMHO, it’s that they can sort of kill sound. But try it and see, of course, Ted. Maybe you do need it for monitoring. I would bet the Rode will sound really nice through it all. I love Rode mics. :)

The orders you have are correct. The comp needs to come after the pre.

Tom,

The other aspect I didn’t mention was frequency response. It is possible that the mixer EQ can mess things up or that the mixer does not have flat response to the same bandwidth as the outboard preamp or your converters.

In general there are three issues in audio - frequency response, distortion (including amplitude distortion or compression) and noise (noise being any signal you don’t want). Any time there is a perceivable difference between audio components you will, if you are careful, be able to measure differences in one or more these parameters. It also means that you can get some idea where to look for problems.

A component which can “sort of kill sound” probably has a frequency response problem if that is happening regardless of level. This could easily be true of a mixer, especially if the EQ does not have accurate knobs.

Compression can also “kill the sound” and in a mixer preamp would probably result in distortion as well since there is no actual compressor circuit. This would not show-up unless the signals are near a clipping point. Getting the gains correct so that no clipping is occuring anywhere in the signal chain can be more difficult with a mixer since it is possible to saturate an internal point even when the input is not clipping. By keeping all the faders at 0 dB or below you will reduce any chance of this (altough most mixers can handle boost as well).

Noise tends to be less subtle and usually can be identified by careful listening. It is less likely to take the “life” out of a signal but may render it unusable anyway.

If you want to be able to keep the mixer for monitoring and minimize the impact on recording you can split the output of the preamp, sending one output to the board and the other to the soundcard. This should work although there is some chance of picking up hum because of the proliferation of ground paths. While combining inputs passively is problematic, passively splitting outputs is usually easier, especially when the output is a low-impedance and the input high (as is usually the case with a preamp feeding either a soundcard or mixer).

There are actually very few true “mysteries” in audio these days but there are a lot of under-explored regions on the map. A few well-understood phenomena happening at the same time can still leave you scratching your head. This is made more difficult by the large amounts of money to be made by spreading misinformation to raise the selling price of various products (Monster and the like comes to mind but almost anything where all the “proofs” are subjective).

Jim