Need Help with V1 of Green Pre??

Hi, I am building a Couple Channels of Green Pre but I am Building an Old version (2 IC"s) and I am haveing Problems Finding detailed info on this Pre....

I have allready allmost finnished assembling most of 2 Channels and have started the PSU but I can not find any Info On things Like what the 500r Trimmer is for and If I can use Ceramics for the Low value Caps (150nf and under) and I also don"t know how to Connect 2 Channels to one Power supply (In series or Paralell??) or info on Proper Grounding....

I also would like to know if there is a way to incorporate a Power on LED and a Clipping LED as there doesn"t seem to be one in the PCB design but in the Pics I have seen I have Noticed both of these Features??

I also need to know if I can use 1N4002 Diodes instead of the 1N4007 Doides for the PSU??(the Prrv is 100v for the 4002 and 1000v for the 4007 and all other specs are the same)...I also couldn"t Find info on what Bridge rectifier to use in the PSU, I have a W005 Bridge recrifier that is Rated at 50v and 1.5 amps ,Will this one work out??

It seems that allmost all of the detailed Info on the Green Pre is for v9 to v14 were I think the one I am building is Version 1......

If someone could Point me towards Info that is specificly for this version of the Green Pre I would be very greatfull......


ThanX a Lot!!!

PS: I have used the Search feature but I still can not find info on these specific questions.....

This is the One I am building...

http://1176neve.tripod.com/id10.html

Did you look here?
http://www.groupdiy.com/index.php?topic=5150
Aharon

Yes....

Another Question...

I am trying to Figure out how to Connect my Transformer to the PSU...

My Transformer is a 2 x 13v AC Center tapped Transformer and I was told by PeterC that it should work fine with V4 of the Green PSU but I don"t know how to Connect it...

The PSU has a +15v input and a -15v Input and a -0v (Ground??) Input and My Transformer has 2 x 13v leads and one other lead but I don"t know if it is the correct lead to work with this PSU....

This is what my Transformer look like:



It puts out 2 x 26 v when running in 110v mode and 2 x13v when running the 220v leads off of 110v.....

Im pretty sure that I just connect the Two 13v leads to the +15v and -15v inputs on the PSU and then just Take the Third lead and connect it to the 0v input...But I just want some Confirmation before I blow the Thing up.....

ThanX

OK, I just did some Voltage Tests on my Transformers useing my Digital Multimeter which I have never used to measure Voltages before...

Here is what I got...With the leads touching the Black and Brown wire I get 12.75v AC and with the Leads touching the Black and Red wires I get 12.75v AC and with the Leads touching the Brown and Red wires I get 25.45v AC....

Does this Help you tell me which wires go to the +15v/-15V and 0v??

ThanX

I have allready allmost finnished assembling most of 2 Channels and have started the PSU but I can not find any Info On things Like what the 500r Trimmer is for and If I can use Ceramics for the Low value Caps (150nf and under) and I also don"t know how to Connect 2 Channels to one Power supply (In series or Paralell??) or info on Proper Grounding....

Click to expand...

1.The 500R trimmer if for setting up the CMRR, which is done the same was as per Rev14 in Peter's notes.
2.Yes, for the nF caps you can indeed use Ceramics.
3.Grounding is universal, it doesn't differ from this version of the pre to the latest version. I star ground my gear, search for star ground info here on the Forum and you will get some good info.

I also would like to know if there is a way to incorporate a Power on LED and a Clipping LED as there doesn"t seem to be one in the PCB design but in the Pics I have seen I have Noticed both of these Features??

Click to expand...

I've not seen too many people with V1 pres that have a clipping LED, if any, they are mainly Power LED's and +48V LED's, I'm sure it is possible, I've just not done it, though a while ago someone offered up a clip LED schematic for mic pres.

The Power LED is easy to do, you can run it off of your +15V rail.

I also need to know if I can use 1N4002 Diodes instead of the 1N4007 Doides for the PSU??(the Prrv is 100v for the 4002 and 1000v for the 4007 and all other specs are the same)...I also couldn"t Find info on what Bridge rectifier to use in the PSU, I have a W005 Bridge recrifier that is Rated at 50v and 1.5 amps ,Will this one work out??

Click to expand...

You could get away with IN4002's, but I tend to use higher value diodes, just remember that is you use the voltage tripler for the +48V rail on the Green PSU it gets yo up to around +-70VDC already. I would er on the side of caution and get a higher rated IN Diode.

The W005 Bridge will work fine, since your input transformer below is about half the voltage of the max voltage of the W005.

It seems that almost all of the detailed Info on the Green Pre is for v9 to v14 were I think the one I am building is Version 1......

Click to expand...

Well the latest revision uses the heart of the Rev 1 version, with the layout being almost identical in the audio circuit, the only major change I think is that on Rev you don't have as may decoupling caps across the lytics.

If someone could Point me towards Info that is specificly for this version of the Green Pre I would be very greatfull......

Click to expand...

Well most of the in of for the Rev14 applies to the Rev1, I've built 4 Rev1's after doing a couple Rev14 and it seems logical if you compare the 2 together that there are a lot of similaries.

OK, I just did some Voltage Tests on my Transformers useing my Digital Multimeter which I have never used to measure Voltages before...

Here is what I got...With the leads touching the Black and Brown wire I get 12.75v AC and with the Leads touching the Black and Red wires I get 12.75v AC and with the Leads touching the Brown and Red wires I get 25.45v AC....

Does this Help you tell me which wires go to the +15v/-15V and 0v??

Click to expand...

Yes it helps, you have kind of answered your own question. Though the transformer is well marked as well which helps.

It is hard to see from your photo's but based on your finding the Black wire is your 0V and the Red and Brown wires are your 12.75VAC's which go to the 15V AC inputs on the Green Pre PSU.

Hope that helps.

Matt

ThanX a Lot... That is what I though, I just needed confirmation to know that I wasn"t Interpreting things Incorrectly....


But Wait!! i think I have a Few more questions if you Don"t mind?? :shock:

I have the Instructions for setting the CMMR But what Is the CMMR?? Also it says in the Instructions that the Trimmer is a Different Value than in the Schematic (500r VS 1k) Can I use a Different Value as 500r Trimmers are hard to Find?? also it says to use a Signal Generator, What if you don"t have one??(What is one??)

ThanX a Lot Matt..... :thumb:

You can use any value trimmer between 500R & 1k

CMRR stands for Common Mode Rejection Ratio, the ability to reject hum from the mains.

also it says to use a Signal Generator, What if you don"t have one??(What is one??)

Click to expand...

http://en.wikipedia.org/wiki/Signal_generator

Peter

Hi, So can I use say a Generated Tone say from my PC directly into the Pre amp useing some form of software??

ThanX

The easy answer is yes... but there are so many factors to consider when doing this... which I'm not going to go into now.

I know this is going to be cheating and taking the easy way out, but the pre will work even without the CMRR set up, and yes it is GOOD to set it up correctly, but it will still work if you don't set it up, in case you were wondering.

Your best bet is to try and borrow a generator. You can use software like Audio Right Mark, but you may need to build some kind of buffer box due to impedance issues.

NY Dave offered up something, try and search for it, i don't know hat he called it though.

Cheers

Matt

ThanX....But I am into a Whole New set of Problems....

EDIT: i have Solved them... I am getting 15.17V+/- DC and +47.75v for Phantom power....

I had to run the Transformer in 2 x26v Mode though but I am not haveing any heating problems with the regulators....

The Problem I had was that the Guy at the electronix store sold be 8R2 resistors and told me they were 8K2 so I was only getting 2.2v for Phantom power and a really Hot Regulator......

Well It works and without too much Trouble and I used the 1N4002 Diodes and these Huge .1uF polyester Caps so hopefully it should be pretty quiet..( I guess I should have used the Polyester on the Pre but they were way too big so I used smaller generic Polypropaline caps)...


Thanx guys....

OK... I have some more Questions if you don"t mind?!?!

I am wondering how much Power each Channel of Pre sucks up because I think my Transformers are only Rated at about maybe 250mA...

( I get Conflicting readings from my Digital Multimeter, When I set the DMM to mA I get about 175mA from the Phantom power but only about 15mA from the +/-15v DC but if I set the DMM to 10A I get about 1.5Amps from the +/-15v DC which I don"t think is Right because these Transformers are really small....)

Also how do i wire 2 of these Transformers together so I get twice the Current but the same Voltage??

Also has anyone Tried different IC"s than the 5532"s and gotten a Better/Different sound??? I have quite a few IC"s that might be compatible like some OPA2107"s which should work??


ThanX a Lot!!!


Cheers

Minion,

Why not just a GOOD toroidal transformer with a 15-0-15V 30VA rating (2amps), this is MORE than enough juice for 2 pres, and can even do around 4 of the V1's.

Toroidal transformers have better hum rejection compared to the big CT type you are using, especially if you plan on putting the transformer into the same rack as the pres.

Off the top of my head I can't recall how much current each Green pulls, though I know it is somewhere in the META. But I think 25ma is okay for a pair of V1 Greens.

Cheers

Matt

Hi, I would get a Torodial Trans but every one I have Looked at was in the $50 to $100 Range which is Far too much money for me to Spend (I only make about $500 a Month and am Disabled) and I have about 8 of these Small ones which I should be able to use if I can wire them together to get more Current....

Do you Know how to wire 2 of these Transformers together to double the Current??? That would really solve the Problem!!!

ThanXx

If you do a search for green + current, you'll get to these links:

http://www.groupdiy.com/index.php?topic=13914&highlight=green+current

http://www.groupdiy.com/index.php?topic=10005&postdays=0&postorder=asc&highlight=green+current&start=15

When I set the DMM to mA I get about 175mA from the Phantom power

Click to expand...

Did you have the meter in SERIES with the power lines? To measure current, you need to break the lines. The easiest way to measure current on the Green is to measure the voltage across the 10R resitors & divide by 10 - Ohms Law.

Peter

Hi PeterC, I am wondering if you might know what is wrong here....

I was testing the Current on the PSU and I must have touched something that I shouldn"t have(all I touched was the Ground and the +48v while trying to test amperage) because I got a Big spark on my Multimeter and suddenly my Phantom power is reading 88vDC....

Do you think that the Regulator might be Blown?? Or maybe a Diode??

Also I read Both of those Posts and got Conflicting Info, someone said something like 13mA and someone else said 250mA but at this Point i just want to Figure out why the phantom power is not working right....


Cheers

EDIT: OK the Diodes seem to be OK so all I can think is that it is the Voltage regulator that regulates the Phantom power.....

What do you think??

EDIT#02: Well I was right I just changed the Regulator over to a new one and it is working fine now...I also decided to Wire up 4 transformers in Paralell so I can Up the Current and it seems to be working fine...I have no idea what these Transformers are rated at but it must have been pretty low as they are very small but hopefully now I should have enough currect to run at least 2 channels....

Do i wire up the seperate pre Channels to the PSU in Paralell??

ThanXX

I also decided to Wire up 4 transformers in Paralell so I can Up the Current and it seems to be working fine...

Click to expand...

You can check to see if the transformer is under-rated. Wire one up to the PSU & attach 1 channel of pre. Check the AC voltage on the secondary. Is it OK?

Switch off, add another pre, check the AC volts, OK?

Keep adding pre channels. If the transformer cannot handle the current, the AC voltages will collapse below the rated level or they might wander up & down if they are on the edge.

Series or parallel? Whaddaya tink? :wink: Think of resistors drawing current in series & parallel....

Peter

Hi PeterC, ThanX for the Tips but I can not connect my Pre channels yet as I am still waiting for some BC550C"s to Show up and I have still to find some 500r Trimmers and Ferrite beads before they will be Completed....

I wired up 4 of these Transformers in Paralell and Connected them to the PSU and everything seems to be working OK.....

Once I get the 2 Channels Finnished I will try what you said to see if I can run both Channels of just 2 Transformers because my Rack Case I am useing is Very small ,Eveb the Caps on the Boards stand higher than the Top of the Case so i am going to have to find a way to Put the top on the Case......


Here is One Question you might be able to answer for me (Hopefully??!!) How would I integrate a Power on Led and a Phantom power LED??

I would Like to somehow connect them to the Power switch and the Phantom switches but don"t know if that will work because I think the Voltages will be too high for the Leds....

Can you tell me how to do this is very easy to understand Step by Step English??

ThanX a Lot!!!! YOU RULE!!!

Hi, I"m sorry for constantly bothering you guys with my problems but I"m haveing another Problem...

I just tried wireing the Resistors to my Lorin switches which from looking at the Pics seemed pretty easy and after a bit of my sloppy craftmanship I finnished them both without any major problems...Or so I thought....

I figured I would connect the Leads to my DMM and read the resistance as I turned the dial on the switch to make sure it was working But the Problem is I am getting about the same resistance at allmost every setting....

Maybe it is supposed to be like that?? the resistance for the First 5 or 6 positions is between 4.09k to 4.14k and then it drops down to arround 2.15 to 2.50 for most of the rest....

Is there some Graph that will show me what resistance I should get at each setting or is what i am getting correct??


ThanXX

Well after looking at the Pictures of switches on this site I have come to the conclution that I have Totally screwed up my Lorin Switches(They came out a real mess also)....

It seems that I have started wireing the resistors starting at the wrong Pole of the switch and in the wrong direction and I somehow ended up with not enough poles for all of the resistors.....

Is there a way I can just use a couple of On off switches to just get Like 3 different levels of gain so I don"t have to deal with those Buggery Lorin switches as I have allready Ruined 2 of them (They do not have the Pins labeled)....


Cheers

The Lorlins are numbered, look closely at the moulding in the plastic.....

The numbers correspond to the letters on the schem.

Peter

"Your" Lorins are Numbered... Mine aren"t....Mine actually look Totally different than the ones in the Pics accept for the Number of Pins and Positions of the Pins and they both resemble a Switch but that is as far as the resemblance goes.....

Actually mine aren"t even called Lorin switches (well when I asked for them by that name at the electronix store all I got was a Funny Look) these are simply 12 position rotary switches but from every thing I looked at they do the Same Thing....


:grin:

Should I post a Pic??