Green with envy... (A Green Pre Review)

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matta

Well-known member
Joined
Jan 11, 2005
Messages
1,640
Location
Cape Town, South Africa
Hey Guys,

I thought this might be of interest to alot peeps who are sitting on the
fence about building a Green Pre, Newbies looking for a first time project
or just anyone interested in my thoughts/results.

I love the Green and I am on Green #4 right now. The first 2 were
?prototypes? on home etched PCB?s which I received from Peter C (Many thanks
Oom Piet!) and needed some basic work to get up and running which was a
great way to test my unknown DIY skills.

From there I went on to build 2 more from quality components like Rubycons
and Wima?s Caps on the silk-screened boards he has available now.

I have been shooting out these little guys in my modest home studio against
what I have and in the ?clarity class? it wins hands down against the 002R
and Soundcraft 328 Console I own, though the Soundcraft did have a musical
peak in the midrange that was quite usable, more so that the ?dull? ?flat?
sound of the 002R.

First thoughts and comments were that the Green is pretty flat... no over
emphasised freqs. Tests were confirmed by sweeping it with signal generator
and scope and it remained pretty flat up to around 15-20K.

Last night I took the Green round to another studio in town to try it up
against some other pres and this is where the fun starts...

For those that might not be aware of the Peter C Green Pre it is Mic Pre based
around the A*M*E*K Mozart /9*0*9*8 topology. A top quality, simple design
(uses basic IC Op amps) which is an easy build even for a complete Newbie,
which is what I was when I started out just a few months ago.

Anyways back to the studio...

So I get there with my little pair in my customized 2U rack (read plain
metal case with holes) and proudly show them off to the house engineer. He
was sceptical to say the least... I gave him the run down of the features
(66db of Gain, Phantom Power, Phase and High Pass filter), showed him the
insides (I built mine sans the metering section, which is optional) and was
ready to give it a go.

He remained sceptical and so decided to shoot it out against a Mackie... a
Mackie! Anyways I went along. We tracked spoken word with both male and
female vocals reciting passages from the Yamaha sound reinforcement manual
(which was just too funny) and then blasted away on a trumpet to test
transient response. The mics used were a pair of SDC Rode?s.

Well the Mackie was blown away and I mean BLOWN away. On vocals it sounded
muddy and undefined with some sonic weirdness in the lower mids
whereas the Green remained clean and even across the board (neither pres
uses a high pass filter/notch). It really showed up on the trumpet track
where the Mackie just crapped out as the headroom was not all that great
plus the transient response paled when compared to the Green.

Okay Green 1 Mackie 0.... I had now got the ears of the engineer (and 2
other engineers who stopped by).

Next he hauled out a Focusrite Green Channel Strip. Now to see what my Green
would really be able to do... The Focusrite Green in no Red or ISA series
but it is still seen by some as a mid-level to high-end piece of gear and
this studio paid a fair bit of cash a few years ago for 2 of these strips.

The topology is similar in that both are IC op amp designs and
transformer ess and so I felt it would be comparing apples with apples.

This time we focussed purely on spoken word, mainly female. The results were
quite amazing.

These pre?s sounded much closer together in the same ball park as each
other but my Green still had a smoother and clearer high end, which was a
little blocked up on the Focusrite.

The tests were done blind wherever possible and in the end my Green came out
tops, 2 out of 3, the engineer who uses the Focusrites preferred his, but by
his own admission it was prob. due to the fact he was ?used to that sound?.

At the end of the session the engineer turned round and asked me to order a
pair of boards and PSU from Peter so they can get a pair.

The DIY audio community wins a game on the Pro Audio away field!

But seriously, not enough can be said about these great little preamps. Kev
Ross along with countless others have sung their praises and I guess I?m
doing nothing new, though I am trying to give you insight into my real world
scenario.

I will at some point build another 8 of these as I think you can always find
a place for these guys and even if you just build one or 2 I?m sure they
will remain practical for years to come in certain studio applications.

They are easy to build, cheap and sound great. I could build 16 for the
price of one of those Focusrite?s, okay so the strip has a compressor and EQ,
but you could always build a bunch of Calrecs and What compressors ;-)

For those keen to find out more about the Green check out the Meta here:
http://www.groupdiy.com/index.php?topic=5150

It has all the info you need to get started, and if you don?t find your
answer in there then feel free to post here and someone will help you.

Cheers

Matt
 
Good review
May I suggest a new forum - Reviews - where we can put stuff like this...
This idea is too good to go away
I know that talking about music like this is like dancing to architecture (copyright - Steve Martin) - but I like this sort of thing...
 
Nice idea indeed to review stuff over here !
Let's add a cover-CD as well :wink:

But serious, some added goodies like audioclips & specific
details could be very illustrative (wherever possible).
Details like some component-info (e.g. cap-types used),
the used supply voltage for DOA's,
pics of studio-engineers face before & after testing etc etc

Regards,

Peter
 
From there I went on to build 2 more from quality components like Rubycons
and Wima?s Caps on the silk-screened boards he has available now.
Just curious, what did you use for all those 22pF caps ?
Ceramic NPO/COG ? Polystyrene ?

Thanks
 
Hi Peter,

Thanks for comments. I will try and see if I can?t get those audio files from
the studio for reference and upload them.

I didn?t take any photos, I thought about it, but
didn?t, darn it! And no cover CD!

I would also love to see a Reviews section where we can out out DIY gear
through it?s paces versus other ?Pro? audio gear.

RE the caps I used Ceramic. I actually posted in another post in which you
asked if anyone had tried them side by side (Poly vs Ceramic).

I posed the question to Peter C and he had tried them side by Side and he
said that is was not a noticeable difference (Poly vs Ceramic in the 22pF
and 150pF values)

What was noticeable was using the WIMA MKS2 caps in place of some cheaper
polys I used in my prototype. The WIMA?s yielded a ?brighter? high end.
Don?t ask for a technical explanation... I can?t give one.

RE components here is a brief run down.

Op amps were all TI branded
Resistors all 1%, 1/4W metal film
Electros were Rubycon YXF series (except the 4700uF one, which was Hitano)
Polys were WIMA MKS2 range
Transistors were Phillips
Ceramics (unknown, though possibly Murata)
1K Trim Pot was Murata
Lorlin switch switch was Taiwan ALPHA
10K Log pot was Phifher

I think that was pretty much it.

I hope that helps you out.

Cheers

Matt
 
Thanks for comments. I will try and see if I can?t get those audio files from
the studio for reference and upload them.
Nice, we'll notice if it was possible.

I would also love to see a Reviews section where we can out out DIY gear
through it?s paces versus other ?Pro? audio gear.
Would be interesting.
For our own health though, I guess we'd better don't make this too luxorious (as a thing for its own sake) since we need to be soldering & playing & recording etc, not computering :wink:

RE the caps I used Ceramic. I actually posted in another post in which you
asked if anyone had tried them side by side (Poly vs Ceramic).

I posed the question to Peter C and he had tried them side by Side and he
said that is was not a noticeable difference (Poly vs Ceramic in the 22pF
and 150pF values)
Oops, I totally forgot and also partly missed it. Sorry & thanks for the info ! I'll be inserting CGO/NPO-ceramics.

I hope that helps you out.
Sure, thanks for the various added info.

Regards,

Peter
 
Thanks Matt
Really nice reading, your review....and great to see your BOM with brands and details. Is it possible to get partnumbers on capacitors (just one of values), op amps and transistors on the shop you use for orders? Just to find the exact ones on our local dealers?
 
Hi, friends. I agree with these reviews. I have reviewd my green with most of hi-end mic pres with fantastic resaults!!!!
I redesigned the mic pre 2 years ago, adding excellent psu, quality components and ofcource double sided pcb.
Believe me, only few pres can stand side by side with my green version...

This is my green mic pre version, called "TsoLias".
http://www.qsl.net/sv3eao/micpre.htm
 
I redesigned the mic pre 2 years ago, adding excellent psu, quality components and ofcource double sided pcb.

Hi,

Nice pics, surely a nicely made unit !

Since you mentioned 'redesigned', I'm curious to what you changed in the circuit.
(imho, selecting higher-spec components but keeping values & topology the same isn't yet redesign - again imho).

Regards,

Peter
 
[quote author="FotisGR"]This is my green mic pre version, called "TsoLias".
http://www.qsl.net/sv3eao/micpre.htm[/quote]
Very NICE!!!!!!!!! :shock: :thumb:
 
clintrubber, look carefully the pre's pcb. There isn't 1000uf in series with the volume switch , no second ne 5532, every semiconductor has its own road to psu, new pcbs, highest quality psu e,t,c.
 
[quote author="Minguta"][quote author="FotisGR"]This is my green mic pre version, called "TsoLias".
http://www.qsl.net/sv3eao/micpre.htm[/quote]
Very NICE!!!!!!!!! :shock: :thumb:[/quote]

Looks really nice!
BTW everyone please notice the smart use of double sided pcb,for building this designs,single sided,leaving the component copper side for a big ground plane...the holes that are not supposed to make contact,are opened a bit with a higher diameter drill bit,the ones that are ground are soldered both sided ! that is at least what i understand from the pictures...
A smart thechnique froma clever radio frequency guy :idea: :idea: :thumb:

Congratulations again...i will definitely try that on my diy pcb's ( i did some double sided toner tranfered pcb's,but this technique aplies to any single sided design
 
clintrubber, look carefully the pre's pcb. There isn't 1000uf in series with the volume switch , no second ne 5532, every semiconductor has its own road to psu, new pcbs, highest quality psu e,t,c.

Hi FotisGR,

First of all, I didn't want to skimp on your very nice unit, please don't get me wrong. I just got triggered by the redesigning-word, got interested in what was done to the actual circuit-topology etc.

Interesting, so you eliminated the big 1000uF cap ? I didn't see adjustment-pots in your amplif-PCB, so how did you do it ? (I have no idea so far how big eventual offset-problems would be)
I couldn't see the values of the four big blue caps, what's their function ?
Are they related to it ?

As for the no-second-5532, I understand you're going directly balanced out from the first '5532, right ?

Regards,

Peter
 
BTW everyone please notice the smart use of double sided pcb,for building this designs,single sided,leaving the component copper side for a big ground plane...the holes that are not supposed to make contact,are opened a bit with a higher diameter drill bit,the ones that are ground are soldered both sided ! that is at least what i understand from the pictures...
You are OK 100%. It's not dificult, i made everything with this technique. In my pcb designs i use always the top for the groung and the bottom for components conections. So, no ground loops...


First of all, I didn't want to skimp on your very nice unit, please don't get me wrong. I just got triggered by the redesigning-word, got interested in what was done to the actual circuit-topology etc.
Don't worry, i am not this kind of guy... :grin:

Interesting, so you eliminated the big 1000uF cap ? I didn't see adjustment-pots in your amplif-PCB, so how did you do it ? (I have no idea so far how big eventual offset-problems would be)
Yes 1000uf is eliminated. If you mean the gain pot ,is there. If you mean balance ofset it doesn't needed. Everything is matched for 0% diference. Even on the pcb the hot circuit is ecactly the same with cold cirquit ( because double sided pcb add some pf capacitance to the cirquit)

I couldn't see the values of the four big blue caps, what's their function ?
They are 10+12=22uf MKP instead the electrolytics.



As for the no-second-5532, I understand you're going directly balanced out from the first '5532, right ?
:thumb: 100%

Cheers
Fotis


Everything, is what you need. Try it . You will like it....
 
Hi,



Quote:
Interesting, so you eliminated the big 1000uF cap ? I didn't see adjustment-pots in your amplif-PCB, so how did you do it ? (I have no idea so far how big eventual offset-problems would be)

Yes 1000uf is eliminated. If you mean the gain pot ,is there. If you mean balance ofset it doesn't needed. Everything is matched for 0% diference. Even on the pcb the hot circuit is ecactly the same with cold cirquit ( because double sided pcb add some pf capacitance to the cirquit)
I meant eventual offset-trimmings.
What do you mean by hot & cold... w.r.t. temp or the pos & neg signal polarities ?

I was considering to double the cap in value and connect it anti-series, with the in-between-node to +Vsupply by say 1MOhm. But based on your unit it looks like that big cap isn't needed anyway - still a bit wondering if this keeps going wel at all gains & temperatures & situations & types of music :wink:

BTW, I saw that the 9*0*9*8-circuit uses even two times a 4700uF...
so I assume you didn't add a 1000uF but you didn't add a 10,000uF, correct ? :wink:

Quote:
I couldn't see the values of the four big blue caps, what's their function ?
They are 10+12=22uf MKP instead the electrolytics.
Cool, didn't expect this big a value so that you could replace the electrolytics. Nice one.


Regards,

Peter
 
I meant eventual offset-trimmings.
What do you mean by hot & cold... w.r.t. temp or the pos & neg signal polarities ?
It doesn't offset trimming... (is there an idea about? )
By hot and cold i mean positive and negative polarity. :grin:

still a bit wondering if this keeps going wel at all gains & temperatures & situations & types of music

There isn't cap at this point. The only problem that i found is an audible "doop" when i play with the gain switch, but no problem for me. I don't play with it the time that i use the preamplifier :grin:

I know that maybe there isn't the right way ( i wish someone can explain it ) but the sound is really better than before. Saying "better" i don't mean more bass or tremples e.t.c. I mean clarity and detail.
I have 2 pieces of "green" mic pre. The one is the "original" and the other is the modidied that we say about. The original is a bit muddy and dirty and the modidied is more clear , absolutely wider and the tremples is absolutely wonderfull!!!
A friend of mine (vocalist) say that the modified green is "driveller" (slobberer) . Sometimes is going front of his mic (tlm103) and play with his lips. Smiling is always says: i don't need to sign, this pre make my slobber to sound like a good song...

Cheers
Fotis
 
[quote author="Bauman"]Matt, great work!!! :thumb:

A review forum is a great ideia!

cheers!
Fabio[/quote]

I second to that!, can't a paralell review forum be set up inside the "Prodigy Professional Forum Index" ?
 
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