A cleanish preamp

[G-Sun]

Hi!

In your opinion, what would be a DIY equivalent to:
- DAV BG-1
- Millennia

I'm considering buying a BG-1 (Millennia is out of budget), but are wondering what my DIY options are.

Thanks!

 

[pyjaman]

Great River MP 2 ?

 

[s2udio]

SSL9K
Easy to build.
Available in several flavours

 

[gemini86]

Could also consider a THAT pre... 1512 into a 1646, doesn't get much cleaner than that.

 

[okgb]

Investigate the topologies which will influence the " sound " somewhat
the millennia  is balanced all the way through the circuit .
the Green pre [ not quite the same  ] has a proven track record , so there should
be some build help available .
The Great River is , I believe indeed great but not the easiest build maybe , probably
go for something without transformers make it easier on your pocket book .

Allot of pres sound clean until compared to others then they just sound different
[ slightly ] sometimes not until pushed or certain sources are used .
the average quality of gear has gone up over the years , so i think it won't be hard to find something you can use

 

[grantlack]

apparently the more recent BG1's use the THAT1510.
so you could do the green, i think there's a 1512->1646 self-etch floating around, or if you're looking for a kitted route the seventh circle t15 has always struck me as similar (also THAT1512 into 1646).  the seventh circle option wouldn't be as straightforward to power though, as he has his own supply convention.

 

[andre tchmil]

IJ Research Albatross . the vocal version

 

[Rob Flinn]

9k out of the self builds I have experienced.

 

[warpie]

Interesting opinions. I've been looking something similar for my beyer m160.
Unfortunately, with the preamps I have available, it's a no no on acoustic guitars and oher quite sources.

 

[G-Sun]

Thanks folks!

It has to be one of the better documented DIY preamps for me to embark on it. (So there goes the IJ Research Albatross I guess )

Transformers is a big yes. Unless someone convince me that I can have an excellent sounding pre without.

"That pre"? Is that just a component  used e.g in green pre, or is it an unique build?

the seventh circle option wouldn't be as straightforward to power though, as he has his own supply convention.

Like very special? So I couldn't just use a JLM AC/DC kit?

 

[grantlack]

Transformers is a big yes. Unless someone convince me that I can have an excellent sounding pre without.

well the DAV is iron-free, and iirc so is the millennia... so if that's convincing enough ?

"That pre"? Is that just a component  used e.g in green pre, or is it an unique build?

just referring to the basic topology.  there's any number of variations, the T15 i referred to as one specifically.

the seventh circle option wouldn't be as straightforward to power though, as he has his own supply convention.

Like very special? So I couldn't just use a JLM AC/DC kit?
[/quote]
i retract my 'not straightforward, it could be done all sorts of easy ways depending on your confidence.  looks like the 6-pin psu connector is just +-30V and +48V with redundant power grounds and a phantom ground.  it's further down-regulated at the module board so as to not fry this particular module.  you could:
a) waste the power and build the module as packaged, supplying the +-30VDC,
b) bypass the regulators and supply it w/ the appropriate regulated voltage from a kit (+-18V would be appropriate).
c) bonus points: should be able to just rectify a +-18VAC transformer and tack it right on at the psu pins, your Vout-Vin would still be >5V at the regs. (18v*1.4~ 25vdc -18 = 7, which is within the lm317/337 spec)
it's all in the schematics/datasheets (wink wink, nudge nudge)...

 

[Rob Flinn]

Interesting opinions. I've been looking something similar for my beyer m160.
Unfortunately, with the preamps I have available, it's a no no on acoustic guitars and oher quite sources.

the 9k works well with ribbons in my experience & has lots of gain available.

 

[G-Sun]

well the DAV is iron-free, and iirc so is the millennia... so if that's convincing enough ?

Yes, that's convincing enough. Many questions about that though.. Told you -newbie

i retract my 'not straightforward, it could be done all sorts of easy ways depending on your confidence.  looks like the 6-pin psu connector is just +-30V and +48V with redundant power grounds and a phantom ground.  it's further down-regulated at the module board so as to not fry this particular module.  you could:
a) waste the power and build the module as packaged, supplying the +-30VDC,
b) bypass the regulators and supply it w/ the appropriate regulated voltage from a kit (+-18V would be appropriate).
c) bonus points: should be able to just rectify a +-18VAC transformer and tack it right on at the psu pins, your Vout-Vin would still be >5V at the regs. (18v*1.4~ 25vdc -18 = 7, which is within the lm317/337 spec)
it's all in the schematics/datasheets (wink wink, nudge nudge)...

Ok, a little more than I understand, but thanks anyway  :

 

[kante1603]

the 9k works well with ribbons in my experience & has lots of gain available.

+1 for the 9k!Have done 2 pieces to check them,now doing an 8 channel unit-excellent for classic recording as well as other sources where you want no or low colour but big dynamic response,superlow ends and tons of gain-just what I experienced and liked to hear of course

Best,

Udo.

 

[Meathands]

It has to be one of the better documented DIY preamps for me to embark on it. (So there goes the IJ Research Albatross I guess )

Once Igor gets the final revision of the Albatross together, I'll be documenting it as I did with the 4KCC. Not sure what your time frame is, but it looks like it's going to be a pretty awesome project.

 

[G-Sun]

Hm.. a 2ch 9k looks interesting.
Are there many major choices regarding transformers and so on? Pad, highpass (Gustavs PCBs)?

 

[grantlack]

Ok, a little more than I understand, but thanks anyway  :

well have you looked at the schematic  ??? ?  pg 2 would be an excellent place to start.  so would this
http://www.national.com/ds/LM/LM117.pdf
look at the equation/diagram on the bottom left of datasheet pg. 1, and compare it to the LM317 (U5) in the T15 schematic.  plug in the resistor values... recognize that voltage?  (pro tip: if you didn't get ~18V, try again.)
also note the similarities in the surrounding circuit to the "adjustable regulator with improved ripple rejection" on pg. 16.  he didn't just pull this circuit out of the clouds.
then look up "ripple" as it relates to current, and find out why you want to reject it.
once you get that, you might wonder what c17 is there for, and why is it so darn big?  do some reading on filter capacitors.
the nice thing here is that you only have to pay attention to half the circuit.  the other half is the same, but using LM337 for negative voltage.
i'm not necessarily partial to the t15, i just suggested it because it would end up being the most 'do it for me' of any of the builds mentioned so far.  good way to get your feet wet, and more importantly learn.

 

[ricardo]

Millenia Media tell us their preamp is based on Graeme Cohen's classic design, the quietest mike preamp in the known universe.
http://leonaudio.biz/cohen.htm
The Earthworks, the quietest mike preamp you can buy, is probably based on it too.

There are other Cohen copies, none of which, including Millenia come anyway near the original Cohen performance.

DIY copies include the Green, Super Green and also Seventh Circle's C84 http://www.seventhcircleaudio.com/C84/C84R20/c84_about.htm

Of these, the C84 is best and could be made to approach the original Cohen very closely (with a lot of work).  The kit has excellent bits.

Their cheaper T15 kit has a paper spec similar to the Millenia and is recommended.  They have excellent support on their forums.

 

[G-Sun]

Ok, a little more than I understand, but thanks anyway  :

well have you looked at the schematic  ??? ?  pg 2 would be an excellent place to start.  so would this
http://www.national.com/ds/LM/LM117.pdf
look at the equation/diagram on the bottom left of datasheet pg. 1, and compare it to the LM317 (U5) in the T15 schematic.  plug in the resistor values... recognize that voltage?  (pro tip: if you didn't get ~18V, try again.)
also note the similarities in the surrounding circuit to the "adjustable regulator with improved ripple rejection" on pg. 16.  he didn't just pull this circuit out of the clouds.
then look up "ripple" as it relates to current, and find out why you want to reject it.
once you get that, you might wonder what c17 is there for, and why is it so darn big?  do some reading on filter capacitors.
the nice thing here is that you only have to pay attention to half the circuit.  the other half is the same, but using LM337 for negative voltage.
i'm not necessarily partial to the t15, i just suggested it because it would end up being the most 'do it for me' of any of the builds mentioned so far.  good way to get your feet wet, and more importantly learn.

Thanks! I re-read your previous post, and are slowly getting it.
It's a nice option, since case, psu with shipping at Seventh Circle is very expensive -at least if you just want two channels.

 

[G-Sun]

Millenia Media tell us their preamp is based on Graeme Cohen's classic design, the quietest mike preamp in the known universe.
http://leonaudio.biz/cohen.htm
The Earthworks, the quietest mike preamp you can buy, is probably based on it too.

There are other Cohen copies, none of which, including Millenia come anyway near the original Cohen performance.

DIY copies include the Green, Super Green and also Seventh Circle's C84 http://www.seventhcircleaudio.com/C84/C84R20/c84_about.htm

Of these, the C84 is best and could be made to approach the original Cohen very closely (with a lot of work).  The kit has excellent bits.

Their cheaper T15 kit has a paper spec similar to the Millenia and is recommended.  They have excellent support on their forums.

Thanks! Many options it looks like
Could you give me the Green vs. Super Green -short story?