All things Green Pre

[kato]

If you liked that, just wait till you try the green with a decent microphone. (mwah-ha-ha.)

 

[sunyata]

Hi,
I have some questions. I would like to fit my Green Pre with some switchable set filters. First of all I'd like a 100 Hz HP filter (standard rumble cut), then I'd like a shelving filter with two different frequencies (3 or 5 kHz), and finally I'd like a set parametric filter in the high end (8kHz).
Does anybody know where I can find out how to build such filters into my Green Pre?

Grateful for any response.

Lars

 

[sunyata]

[quote author="kato"]If you liked that, just wait till you try the green with a decent microphone. (mwah-ha-ha.) [/quote]

So, do you have any suggestions? Something that won't ruin me. Is it possible to change caps in my Röde NT1000? Would it be worth the effort?

/Lars

 

[kato]

[quote author="sunyata"][quote author="kato"]If you liked that, just wait till you try the green with a decent microphone. (mwah-ha-ha.) [/quote]

So, do you have any suggestions? Something that won't ruin me. Is it possible to change caps in my Röde NT1000? Would it be worth the effort?

/Lars[/quote]

I'm sorry - I'm really just kidding.

I had an NT-1 that sounded really harsh and unnatural. But i understand some are better than others. NT-1000? or NT-1?

I bought mine in 1998, sold it in 2000 because my voice simply sounded better with every other mic I owned.

So all I'm suggesting is that a different mic pared with the Green might cut down on the harshness. Try a dynamic too and see if you like it.

Glad to hear your Green sounds great. Mine does too!

 

[sunyata]

Where can I find a design for a DI/instrument-input-buffer for the Green Pre?

Best regards

Lars

 

[sunyata]

[quote author="kato"][quote author="sunyata"][quote author="kato"]If you liked that, just wait till you try the green with a decent microphone. (mwah-ha-ha.) [/quote]

So, do you have any suggestions? Something that won't ruin me. Is it possible to change caps in my Röde NT1000? Would it be worth the effort?

/Lars[/quote]

I'm sorry - I'm really just kidding.

I had an NT-1 that sounded really harsh and unnatural. But i understand some are better than others. NT-1000? or NT-1?

I bought mine in 1998, sold it in 2000 because my voice simply sounded better with every other mic I owned.

So all I'm suggesting is that a different mic pared with the Green might cut down on the harshness. Try a dynamic too and see if you like it.

Glad to hear your Green sounds great. Mine does too![/quote]

The test was done with a NT1 (maybe a NT2). I have a NT1000 myself. I think I read somewhere in a forum about somebody who replaced the caps in a Röde mic

 

[Hammond]

Hi all
I've a 30VA dual 15v power trafo.
From what i understand i can connect it with secondary in series or in parallel ( doubling the current ) which way works best for the green?
I have power 2 ch.

Thanks in advance

 

[peterc]

You to connect the secondaries in series or else you will not get the required voltage for the +15v & -15v needed for powering the mic pre.

Petr

 

[Hammond]

Thanks Peter, so my voltages looks like that:

+15.1
-15.2
+63.8

isn't too much for the phantom?

 

[peterc]

Those look good, I assume that the 63v is before the phantom regulator? If you are getting 63v after the reg, then it is blown....

I would use 100v electrolytics for the doubler, 63v are right on the edge.

 

[Hammond]

All right

I have 48.5 after the regulator and 63.4 before.
The 63.8 was between 48v & V- :roll:

do you mean the 47uf caps? if it's so i already have all four of them 100v

 

[ENS Audio]

Hi, Im not sure if this question was already asked during this thread but for the 4700uf 16v would that alter the Green Pre design if I "doubled" to a max Volts rating of 30V??

Also, is that cap when im meauring for voltage supposed read near or at its maximum voltage rating, as well as the other caps? Just curious, Im quite the knowleable newbie but there are things that should be so damn obvious to me by now that I didnt learn along the way.

I've been working on 8chs on and off for about 8months and because I rushed through carelessly I've found that there are mistakes through and through despite that some channels are just....there


Say so that future newbies will not have to go through the agony that I've been going through, I decided to start making an assembly manual of sorts similar format that the LA2A and N72 manuals are in which Gregory did an awesome job on btw.

I have some random stuff and will be using Corel Draw for the "visual" references and so just PM me if interested.

Now back to the question again :green:

 

[peterc]

30v caps will be fine here, might be a bit LARGE though!

A construction guide would be welcomed, I am sure. Thanks.

Peter

 

[ENS Audio]

[quote author="peterc"]30v caps will be fine here, might be a bit LARGE though!

A construction guide would be welcomed, I am sure. Thanks.

Peter[/quote]

Now when im measuring voltage of the 4700uf 16v cap am I supposed to get voltage measurements at or near maximum capacity?? Reason for asking is that im only getting a few volts and havent got a chance to reorder some more 20v zeners which may be the culprit.

 

[ENS Audio]

Another lame question...the BC transistors that are used in this project appear to be 45v max rating from what theyre saying on mouser.com

Would it alter the functionality of this circuit if lets say I used something rated at 50v???


Yeah I just want to be sure here if im using 48v and the max rating of the BC550 is 45v wouldnt that cause the transistor to "fry"???

once I get confirmation on some of these questions im going to make a reference to votages/measurements for some of the main components.

BTW...would the 863-BC550CG fare as a better choice?

Dont mean to ask so many questions, I just want to clear up any confusion once and for all, for my sanity (whatevers left at this point) and your sanity as well :wink:

Thanks,

 

[peterc]

The 48v will not get to the transistors, it is blocked by the input capacitors. The zeners are there to block spikes generated by the 48v switching & transients.

Peter

 

[ENS Audio]

[quote author="peterc"]The 48v will not get to the transistors, it is blocked by the input capacitors. The zeners are there to block spikes generated by the 48v switching & transients.

Peter[/quote]

and when measuring voltage of the "input capacitors" is there a particular amount of "volts" that I should be getting or do I need to make sure the voltage reads near max capacity?

 

[ENS Audio]

Bump...If someone to whom has a green pre working 100% properly and could tell me what voltage theyre getting from the 4700uf cap and the other caps near the input of the preamp, I'll post the voltage references in the User/Assembly guide that im looking to put together.

Being that Im still somewhat "green" with some electronics theory, I am just not sure if the caps im referring to in particular are supposed to read at or near maximum voltage rating and also about the zeners if there a specific voltage/current measurement I need to look for.  Apologize for asking what may be a "no brainer" but i'd like to at least put together some resource guide so that there won't be any need for asking those basic/redundant questions

 

[ENS Audio]

Bump.....

 

[jdbakker]

Bump...If someone to whom has a green pre working 100% properly and could tell me what voltage theyre getting from the 4700uf cap and the other caps near the input of the preamp, [...]

In an ideal world you'd see zero volts DC across the 4700uf cap. With perfectly matched parts[1], that capacitor could be replaced by a short.

In the real world, input transistor Vbe mismatch and (to a lesser extent) phantom decoupling capacitor leakage current mismatch will cause a DC offset voltage between a few mV to a few tens of mV with unknown polarity to appear across this capacitor. Without this capacitor this offset voltage would appear across the gain-setting network, causing audible clicks when the gain is changed.

Note: as with all other steady-state measurements, this offset voltage is best measured with a 150-200Ohm resistor between the input terminals, to simulate the impedance of a typical microphone. And while it may be tempting to try and match the transistors and the phantom caps to eliminate this cap altogether, the offset voltage will drift over time and temperature such that one single trim setting will never get rid of all the clicks.

[1] or a good servo

JDB.