That Minimalist Mic Pre

[mikka]

I've been off in la la land for a while. Is the schematic of a FET based DIY mic pre that was highly praised in Tech Talk over at Recording.org still available? I can't seem to find it using the "search" function.

Did it end up sounding wonderful? (subjective, I know)

Thanks

Mikka

 

[tony dB]

Was that the Hampton maybe?

 

[mikka]

I'm not sure. I don't think so. I checked out the Hampton and it looks as if it has a lot more components. This one was a DIY project in Tech Talk I think. Apparently had a very forward vocal sound.

Thanks

 

[tony dB]

i know of a preamp build by Sloblo but that was a valvething, straightforward no nonsense and very good sounding on vocals. I used it once on a project in my studio and liked it very much for that peticular type of vocal.

Tony

 

[rafafredd]

I don´t think there is anything more minimalistic than the Hamptone FET preamp. That´s probably what you are talking about. Note that this is not the hamptone tube pre, it´s the FET one.

 

[mikka]

Thanks Tony. I'd be interested in finding them but I can't really buy at the moment. How are they spelt? I can't find "Sloblo" on the net. For now I'll need to build something if I want champagne quality on a beer and chip budget.

 

[tony dB]

if you search for Shalimar you'll find stuff on this forum about it.
I belief Shalimar and Sloblo are the same person.

 

[mikka]

Many thanks Tony.

 

[rafafredd]

[quote author="tony dB"]if you search for Shalimar you'll find stuff on this forum about it.
I belief Shalimar and Sloblo are the same person.[/quote]

Yes. This is the same person. In fact, Shalimar = Slowblow = Slowie = Sismofyt... Many names! Try this links:

http://www.wwnet.net/~dhicks/misc/stuff.html

http://www.sismofyt.net/dual_srpp.htm

http://www.mindspring.com/~absentia/slow/index.htm

 

[Svart]

i looked around but didn't see the FET preamp...

 

[dominique]

hey,

it seems you don't want the ultimate "true" sound, but something nice sounding AND simple.

The most simple mic preamp I ever built was just containing one bjt transistor. I'm sure you'd be surprised at how good that sounds. The thing is just it has to be adapted to your mic sensitivity and impedance.

I mean something like in the schematic below (if you don't need a symmetric input) , maybe use a higher voltage than those 9V and adapt the resistor values.

Trying this and thinking about usual mic preamp designs, I was astonished at how much more effort is needed to gain so little advantage...

Cheers,
Dominique

 

[Svart]

and thus the brickwall in innovative design.. seems that for a while we've just been revising the same tired designs trying to scratch every little ounce of performance out of them. We've done valves, we've done BJT's, we've done FETs of all kinds, we've done opamps... what's next?

I keep asking myself that question.. but i keep drawing a blank.

 

[tk@halmi]

People, we cannot stop. We have not done a MOSFET preamp yet. :grin:

 

[PRR]

> We have not done a MOSFET preamp yet.

I have.

High noise, distressingly large non-linear input capacitance, not a lot of gain and not that linear.

MOSFETs work great if you slap them hard. Output stages. Not input stages.

I'm sure it can be done. Maybe done well. I do notice that MOSFETs have improved since I last looked at it (around 1980). MUCH more power, better Gm/Cin ratio. Noise has not been a priority (except in that very noisy devices are likely to be defective and prone to early death) so I don't expect to find a real-quiet MOSFET.

But if you want very-funky: get an old CMOS hex-inverter logic chip in the 400x series (no extra letters for high speed low voltage) and put feedback around 1 or 3 of them. CMOS logic does have a usable "linear" range, but not too linear, not colorless. If you don't need exactness, it can be one $0.09 chip, one resistor, two caps, and a 9V battery.

 

[Consul]

Would those big power op amp chips, like the LM3886, be useful for a mic pre? I've been thinking about that one, but as usual, have not the money to try something out.

 

[Consul]

You know, why couldn't you do something like that?

What's the issue when driving a transformer? The power of the output stage, right? (Okay, I might be wrong, but we're all here to learn, right?)

So, start with a 5532 for an unbalancing input stage, run that signal to an LM3886 or something similar (maybe a lower-power variety), and use that to drive a transformer output, like one of those inexpensive API output jobbies.

The design seems pretty straightforward, and it wouldn't be an expensive build, unless you want a nice input transformer.

I'll try to draw this up today. I 'll post it in the Drawing Board, though, if I do.

 

[strangeandbouncy]

Darren,

those cheap API output jobbies are not available at the mo' . . . Profile are at some kind of loggerheads with over them

Andy P[/i]

 

[alk509]

[quote author="strangeandbouncy"]those cheap API output jobbies are not available at the mo'[/quote]

Yes they are.

http://www.groupdiy.com/index.php?topic=5856

Peace,
Al.