The official G9 help thread

[braeden]

That's good to hear, also... I hate Farnell :-X

 

[mrdarwin]

Hey Hey!!!

48VPSU works better with a zener 56V than with a 4148...

and there was a shortcut with the screening can of OEP A3E on channel 2: 48V came to 6k8 resistors and after nothing because  a contact with ground and phantom.

SO EVERYTHING WORKS FINE, NO HUM, FANTASTIC!

Thanx to BRAEDEN and GEMINI86 for help

and SPECIAL THANX TO LORD OF DIY, MR JAKOB FOR HIS AWESOME DIY PROJECTS!!!

Did someone try the G9 line input on a master mix???

 

[Graph]

I am having some problems with my G9, i have used it for 2 years now.

I really likes how it sounds. But in 2 years, the gain switch(lorlyn) its getting some noise when it rotates.

The only problem is a small ground noise in channel 1()the only one i made.. at -75dBsFS. measured in logic. This noise doesnt changes if i add some gain, if i move the master pot, the noise is fixed at -75dBs.

What i tried:
If i disconnect the cable which goes to gain switch, noise remains.
If i disconnect any tube, ground noise goes away.
If i disconnect the cables which goes for: Line/Instrument/Mic+48v, polarity, master and LF, ground noise goes away.
My polarity switch when i bought i didnt bought the right lorlyn switch, as it is, 3 positions. 2 positions, inverting and non inverting, and 1 position without connection, in that position, there is no signal. so i guess the problem is before it.



For caps in general, i used Polyester, tubes i used, first time i used a Sylvannia 12au7 pair NOS, which didnt sound too good, they fried after 6 months in use(i guess that happened because sometimes in my studio i left it ON, for more than a week. Tubes i use now, are JJ 12au7 pair from tube depot).

How should i debbug the preamp to find the problem? Jack´s Input and output cables are shielded.

It is not a very big problem, if i record anything, from a mic, for example, it doesnt bothers, but if i record a guitar through a DI box, and use some plug ins to give high gain, noise is very present, same as if i reamp it through a high gain Amplifier.
Thank you

 

[gyraf]

..if you have same-level hum, regardless of gain setting, it's likely to be power transformer hum introduced into output transformer. Try moving/rotating power transformer(s) and/or move output transformer further away from power transformer..

Jakob E.

 

[gemini86]

Have you swapped tubes between channels?

 

[Graph]

..if you have same-level hum, regardless of gain setting, it's likely to be power transformer hum introduced into output transformer. Try moving/rotating power transformer(s) and/or move output transformer further away from power transformer..

Jakob E.

Oh well, if thats the case i will have to forget about it. Since i am using normal transformers, not toroidal ´cause they are very expensive here in Argentina(and i havent seen a 220:240 + 15+15).

Channel 2 is unusable, moved transformers and tubes to channel 2, and there were more hum than signal.

 

[gemini86]

Can you find a 220:12v and a 220:15v toroid?

then wire them back to back, just like the schematic shows.

 

[mrdarwin]

..if you have same-level hum, regardless of gain setting, it's likely to be power transformer hum introduced into output transformer. Try moving/rotating power transformer(s) and/or move output transformer further away from power transformer..

Jakob E.

Oh well, if thats the case i will have to forget about it. Since i am using normal transformers, not toroidal ´cause they are very expensive here in Argentina(and i havent seen a 220:240 + 15+15).

Channel 2 is unusable, moved transformers and tubes to channel 2, and there were more hum than signal.

Hi!
A quick suggestion...
When I wrong wired input instrument of my G9 preamp, I was having more hum than signal and noise in gain switches, because circuit was "open" between output of input transformer and C2(220n). see schematic.
So you should test continuity of your front panel jack connections.
Perhaps your switching jack instrument input is not working.

 

[Weimann Stage and Sudio]

Hey Guys,

First im new in this forum so i like to explain myself first:

My name is Michael 21 from germany and im working as a event engeneer and my english is ot the best sorry for that.
im a diy er fo about 3 years but now its time to get some "serious" studio gear

So:

Im interestet of building the G9 my Question: is there an up to date BoM? would be Great ...


Thanks and have a nice sunday, Michael

 

[gyraf]

The BOM should be quite correct - only thing is some 220nF/470nF confusion, which is close to unimportant for performance.

Jakob E.

 

[mrdarwin]

Hey Guys,

First im new in this forum so i like to explain myself first:

My name is Michael 21 from germany and im working as a event engeneer and my english is ot the best sorry for that.
im a diy er fo about 3 years but now its time to get some "serious" studio gear

So:

Im interestet of building the G9 my Question: is there an up to date BoM? would be Great ...


Thanks and have a nice sunday, Michael

Hi!
I finished my g9 one week ago and it works perfect!
Just  folow the bom on Jakob's website page: http://www.gyraf.dk/gy_pd/g9/g9_components.txt

 

[Graph]

Can you find a 220:12v and a 220:15v toroid?

then wire them back to back, just like the schematic shows.

I cant, i have to send it to make them, and minimum order quantity = 10  of each one, cost like 80usd each one(total 20 transformers = 1600usd ). Maybe in ebay i can get lucky, or is there any international manufacturer which i can ask them for? If i can find them, maybe i will complete second channel and get nice caps.

EDIT: Oh.. nice price in ebay!!

 

[gyraf]

RS Components and Farnell are represented in Argentina afaik?

Jakob E.

 

[Graph]

RS Components and Farnell are represented in Argentina afaik?

Jakob E.

Yeah, but 4 times its international price.

 

[gyraf]

Horrible.

Time to start your own distribution company then

Jakob E.

 

[ramshackles]

Hiya. Almost finished my G9, but just want to verify that Im connector the power switch correctly, before I kill myself...

I\ve drawn a crude picture, which is attached. What I think is the correct way is:

- Neutral pin on IEC connector goes to power switch and the output of power switch goes to one of the primaries on the trafo (brown)

- Live pin on IEC connector goes straight to the other primary

- Earth pin goes to chassis (should pin 1 of the xlrs also go to this pin?)

This good?

Cheers!

 

[ramshackles]

dumb question...a clearer mind and obviously - its a 2 pole switch so I can switch both L & N...duh!

 

[gyraf]

;D

 

[ramshackles]

Way hay!
My G9 is done. I've tested it with a condenser mic and it seems to work fine. I'll test all settings tomorrow.

One small problem - When I pull out the output xlr cables (I've not tested with othe connections yet), if my other hand is touching the chassis of the unit, I get a lovely little shock. It's not particularly strong...but strong enough to jump away and curse

Any ideas what causes this - have I messed up my grounding? All the chassis pins on the XLR connectors are tied together, and pin 1 on the output xlr's are connected to this. This then goes to the power ground on the IEC connector, which is connected to the chassis.

 

[gyraf]

All XLR pins1 should go together - otherwize correct.

Take very much care if you have voltage on chassis - specially check that nothing from mains primary is in contact with 0/chassis. If in doubt, use a grounded mains outlet. And measure AC voltage from chassis to a local earth to verify what voltage you have floating around there.

The only situations where I've had this problem is when the G9 is connected to a ungrounded computer, which's powersupply can mess up ground like this.

Jakob E.