Tube pre-amp for recording?

[guitardude57]

So you aren't going to transformer couple then?
Low impedance would be highly desirable.
There are some sources for Neve type trannies out there. With tubes.....oh boy!

[selloutrr]

Is tube not the opossite of squeekie clean? If he is after transparent clean tell him to buy a grace 801. The best part of tube is the color and dimension of the image and how it breaks up when pushed. Not it's cleans. When I need clean tube is not what i plug in!

Make him a nice API 312 knock off with a hardy op amp and jensen iron should run you about $400. prob cheaper then a studio quality tube pre. And put a big smile on his face!

preamps are the last place you want to cut corners. I'd rather do a session with only sm57's and a few nice preamps then any neumann or Sony c800 or eLam and a lithargic preamp.

Just trying to help

[guitardude57]

I agree, there are a lot of kits out there to build API, Neve, and many others.
The 312 is a wunnerful sounding unit. 1081 and 1073's are nice too. 1073 is an easy build.....the 1081 is pretty hairy. You could do a 312 pretty easy, and it would flip your friends' wig for sure.

[bluesfendermanblues]

Great post guys.

I have a little different take on the recording thing.

Prioty of studio gear purchases
I don't believe that the pres are all that important. Don't get me wrong they are, but only after you have

1) great monitor listening area acoustics
2) Monitors you can trust (Dynaudio BM5's are ok, but not great)
3) The right mics. SM57 is the standard, but try a Beyer M160 its classes abobe - add in a SM57 or MD421 and you're close to pro sound quality.

The preamps are barely noticable unless the have the above. When you read interviews with top pro producers, they talk a lot about the preamps having this or that sound, but most (99%) of all home recordists won't be amle to hear any difference between these, because the don't have the above in place first. Preamps are the spice in the dish - at best!

Don't believe that preamps are more important that having the right mics.
When someone claim something like that, have them demonstrating it to you. My bet is that you'll be hard pressed to hear any difference at all.


Sound of Pres
I have access to
- (DIY) Neve 1272 pre,
- (DIY) Gyraf G9 tube amp pre and a
- Sytek MPX-4Aii
- build in mic pres in a MOTU MK828II

First of all I never felt that tubes are 'warm' on the contrary. Comparing the the NEVE (transistor) with the G9 (Tubes). The Neve is warm (probably due to the carnhill transformers) whereas the G9 har a nice top end. The Sytek (uses no transformers) is squiky clean like the build-in pres in the MOTO 828.

[M Fowler]

Come on guys squeaky clean as far as tube pre goes. Kind of like saying the clean channel on a Twin Reverb. He just doesn't want gain or distortion options.

I would like to build that API 312 knock off as well thanks for suggesting that. I better get googling unless you got the info handy.

Mark

[Jana]

Some random Monday morning musings (coffee hasn't kicked in yet either)--economical yet decent seems to be the watchwords.

Mic input--get one of those Shure low to hi / hi to low impedance microphone adapters. Most musicians have one in their gig bag that never gets used. Rip it apart and inside there is a little transformer that you can use to bring a balanaced, low impedance mic into the preamp and connect to the first tube stage.

Don't use the typical fender/marshall style tone circuit as shown in the alembec schematic. They are anything but flat. Great curves that we all know and love for guitar but there is no "flat" setting to be found with them.

Instead, use a bass/treble tone circuit that really can become flat. Bass is cut or boost, treble is cut or boost. No need for mid control because the bass and treble give you that--cut bass and treble and you have a mid boost. I seem to have a vague recollection buried in the back of my mind that Bandaxall is the word to search for on this.

Follow this up with a gain recovery for the tone and a low impedance output. A cathode follower would do nice. No need for an output transformer unless you want to go back to a balanced line out. On the other hand, an output transformer would let you do a totally isolated output to avoid ground loops and the like.

Be sure to test and watch gain levels between stages so that it stays clean.

A bass boost/cut switch could be implemented with a selectable bypass cap on the first stage. Have a .68 or 1 uf cap for bypass all the time and another cap, 25uf that can be switched on in parallel with the .68.

Just my ramblings.

[Bear]

The deep end of recording studio DIY: http://www.prodigy-pro.com/diy/

You've gotta ask yourself at some point, though: am I a recording engineer who plays music or a musician who records? The best DIY recording priority for the later is probably one of the better priorities for a good recording -- get your room sounding good and start from there. If you get a few good pieces of equipment from there and don't get lost trying to get two of everything like you're Noah, then you can make good recordings. Limited choices in the recording chain helps you focus your ears in on the essential thing, the performance in the room.

[guitardude57]

Jana,

You have the right idea. The tone stack is unlike guitar amp types for the flat/cut/boost. Some have additional mid cuts, and most are active boost/cut from anywhere from 2 to 5 band.

Transformer/transformerless designs work well for personal preference reasons.

I prefer transformer types myself, because of the warmth imparted by a great design of the tranny. It is nice to have a HI Impedance in/out, but Low really needs to be there to eliminate noise of cable runs and correct level with other +4 Input of equipment/recorders. No reason not to have a hybrid build with a FET and/or tube circuitry switchable. Or one or the other. Lot's of wonderful options. When the budget allows plan on building a few of these myself

In a lot of cases, the Mic Pre will bypass the desk channels straight to the recording medium. Money not being an object may also include a fast compressor, a slower compressor, an EQ of some type. Everyone has their "magic" combo that works for them. All sound different and match well or not, with a particular mic choice.

Mics are a whole other issue. You have guys that use the old SM 57, and others use Royer 122 ribbons for recording guitar. One is $100 the other is $1600. I have a nice mic collection that allows me to experiment different sounding setups. Most of the time a 57 sounds the best. I'll use that and a 1200 buck mic for an ambient. Or a $100 one for an ambient. Depends on what i am going for.

I use a Focusrite sometimes as a front end or as a processor. Works well as a vocal bus processor for vocals when I do Pro Audio gigs.

But, I love the sound of my MOTU 896HD Preamps, even though it is a Transformerless design. Works great into my monster recording computer.

All in all, everything in the chain from the source to the end medium, makes a difference in what it sounds like.

Mark,
There is a whole network of builders like us, into knock off LA2A's Calrecs, Neves, API's and SL's. You can buy the boards, and other parts from them. There is a cat in Hungary, that makes real nice metal boxes with awesome screen jobs. Sometimes, a fellow has a bunch of original components they are selling off. Like Neve modules from the BBC Studios used in the 50-60's.

Do a search for DIY LA2A or Mic Pre kits. These guys are friendly and extremely helpful........like us.

[M Fowler]

Thanks everyone still pondering my simple design and taking your notes seriously.

[Andy Le Blanc]

I had a thought.... (ouch)

You could use a series of wein bridge networks

C1 = C2..... real simple the larger C the lower the frequency

they are driven from a low imp. source like a follower and sum like a mixer.

the gain stage can be biased any way you choose, ( that 4.7 is meg.).

[selloutrr]

If you wanted to make a simple low mid hi eq track down a Joe meek schematic they make a very musical simple eq and a sought after preamp.