D.I.Y. Pre-amp

operator_tape · Post by **operator_tape** » Tue Feb 28, 2006 7:23 pm

I have to ask this because I am freaking out trying to figure this out, I really need a 8 channel mic pre, what is in your opinions, the best sounding mic pre for the cheapest amount of money, in terms of sound, to D.I.Y. any suggestions would be helpful.

peterc · Post by **peterc** » Wed Mar 01, 2006 12:21 pm

Operator_tape

I hope I am not blowing my own trumpet too loudly here, but the Green pre is an excellent DIY pre.

Have a look at a couple I have built here:

http://1176neve.tripod.com/id15.html

It costs between $50 & $75 per channel (excluding the case & PSU) depending on where you source the parts. It uses easy to find parts & there is a parts kit available ($65-00)

Email me for further details. peterc(at)onwe.co.za

Peter

matta · Post by **matta** » Wed Mar 01, 2006 3:23 pm

Pete,

You don't blow your own trumpet, you just hold it in the winds... Hah hah

But seriouslly, I can't praise Pete's Greens enough. I have built a few over the last year and just completed a 4 channel version of his earlier work (sans metering, on board switches and low cut filter).

If you are looking for easy to build pre that sounds great, is clean, has a great transient response, gobs of headroom and gain (65dB's), look no further.

Here is a pic of my new 4 channel unit.

Cheers

Matt

peterc · Post by **peterc** » Thu Mar 02, 2006 10:21 am

Thanks for the cool words Matt! Your biltong's in the post...

Peter

marc · Post by **marc** » Thu Mar 02, 2006 11:26 am

Wow. Those pres (the one above, and the one on 1176neve.tripod.com) look amazing! That seems not a bad price range at all, what do the PSUs usually run?

matta · Post by **matta** » Thu Mar 02, 2006 12:49 pm

Hey Marc,

Thanks for the kind words.

I'm not sure what your question is? Are you talking about costs or voltages?

Cost of the PSU board I think is under $10 for the PCB and you could knock one out for around $20-$30 in parts excluding the power transformer.

If you question was related to running voltages, it is a bi-polar design, +-15V, with a +48V rail for Phantom Power.

In a blind test at a local studio 3 of 4 of the engineers chose my pres over the now discountinued Focusrite Green Mic Pre (similar IC topology), and cost a fraction of the price to build...

Pete, Biltong, I LOVE Biltong, none of this nancy beef stuf though, bring on the Kudu or Springbok, game is there to be eaten!

Cheers

Matt

hyde maintenance · Post by **hyde maintenance** » Thu Mar 02, 2006 10:07 pm

Um...aren't the Focusrite Green's generally regarded as...well...sort of not so special?

matta · Post by **matta** » Fri Mar 03, 2006 12:13 am

Well they were no ISA or Red series, but then the topology is different since both the ISA and RED are transformer coupled, the Green series were IC based/balanced... much like the AMEK / Pure Path, which I would put in a similar battle class..

The Focusrite Greens are, at their time of release VERY decent, leagues ahead of the now budget 'Platinum' range.

Peter 'Greens' are based around a IC design of a classic high end console pre...

Matt

eeldip · Post by **eeldip** » Fri Mar 03, 2006 9:27 am

hyde maintenance wrote:Um...aren't the Focusrite Green's generally regarded as...well...sort of not so special?

i think at under $100 a channel you shouldn't expect miracles. i just ordered some PCBs... now to hunt around for housing.

hyde maintenance · Post by **hyde maintenance** » Fri Mar 03, 2006 12:14 pm

OK ok. Fair enough. Just sayin' is all. Jeez. (translation- Yeah I think I might order some too).

matta · Post by **matta** » Sun Mar 05, 2006 11:47 pm

I think at under $100 a channel you shouldn't expect miracles.

I would expect it to sound better than any IC based design under a retail price of say $500, if not more.

Sure, they will not fit the bill for everything. But for a clean, quite pre-amp with loads of gain, it is awesome. Plus it is a fun 1st time DIY project.

I also have a pair of Telefunken V672's, Spectra Sonics 101's, Hamptone JFET's and these hold their own, but sound VERY different.

Firstly all the aforementioned pres feature discrete op-amps, while Peter's feature the NE5532 IC opamp, which is not to be scoffed at.

Sure there are lower noise, faster response designs today (THAT, Burr Brown, LT etc), but it is the implementation that counts. The same chip is found in the Focusrite Red range, and many 'vintage' designs we pay ALOT of money for. And Peter? design shares some similarity with an old AMEK design.

Not that this is at all a scientific test but I did an A/B with my stock Digi 002R Pres vs the Green Pres, using the 002R as the A/D, straight into Pro Tools, with no processing. The mic was a basic Chinese LDC, an ADK-A51.

002R Acoustic Guitar 1.5MB
Green Mic Pre 1.5 MB

Take a listen, let me know if you notice a difference.

Cheers

Matt

Spark · Post by **Spark** » Tue Mar 07, 2006 7:30 pm

I think it sounds pretty good compared to the digi pre... maybe my next project? hmmm,.....

amishsixstringer · Post by **amishsixstringer** » Wed Mar 08, 2006 7:24 pm

That thing sounds very pretty. I mean, the 002R pres shouldn't be too hard to beat, but the Green certainly has a sweet character to her. Lots less mud.

bplr · Post by **bplr** » Wed Mar 08, 2006 8:52 pm

i'm pretty confident that the answer is no, but i'll ask anyway:

is there a way to put optical out on an 8 channel green pre? i need to take advantage of my digi002 opti ins and could use another pre project.

justin

matta · Post by **matta** » Thu Mar 09, 2006 5:09 am

The answer is no, not unless you can build a ADC from the ground up

There are a couple inexpensive boxes that can do this for you, the best
value for money One is the SM PRO A08
(http://www.smproaudio.com/A08.htm), $150, and it will convert 8
analog inputs to an ADAT out, for use with your Digi ADAT port.

It uses the Delta Sigma converters, 24Bit/96Khz, which are used by some
higher end AD/DA's as well, great value for money.

The Green certainly has a sweet character to her. Lots less
mud

Indeed, and that is a single track, imagine the definition on a 24 track mix
tracked on the Green's vs the 002R...

Cheers

Matt

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