The official G9 help thread

caseyc said:

BUT, ok i have read this thread and cant access oscillation problem thread for some reason....but on the the three last gain settings it both channels it totally goes too high...

Click to expand...

I've been trouble shooting a similar problem but I have high freq osc only on the right channel (closest to the PT) with the last 3 gain settings...I would imagine this the same issue that needs traces cut but only on problem channel?
Edit: I'll answer my own question and say yes, the DI mod helps tremendously.
I just performed the mod and it ended any HF oscillations in the furthest gain settings.

Also, I've been researching ground schemes for the G9 design and have found that there are many seemingly successful grounding schemes - pin1 inputs strapped, inputs and outputs strapped, 1 input strapped directly to IEC, starground to chassis : which is the best?

Heres mine BTW, and other than the oscillation, its pretty quiet..:

Edit: I think I'm going to pull the output grounds and just tie input and IECplug to a star ground at chassis.The pres are pretty quiet untill they are full out then have just a trace of crackling and hum. I'm trying for ultra-quiet..

hi, i made a lot of g9 and i love it
i have 8 channels in my studio using OEP and 4 channels using Lundal transformers

i would like to do a dual channel without transformer (with op amp or something else)

somebody as an idea about that?

thank you

David

  Hi,

A little help please  ;D

  I am getting together a parts order list for a G9 and have a few newbie questions..sorry.. ;D

I think I'm good with the resistors

Output Level pot - 47kb (log) 6mm - any suggestions ?

10k Trimmer 5x10mm or 5x2.5mm  - any suggestions ?

C6,106 - 68p 50v ceramic, is this one correct?
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BC1011TR-ND

Need voltages for, C8,108 - C9,109

D3,D4,D5, - ZD39 - any suggestions ?

D6 - is this correct?
http://www.mouser.com/Search/ProductDetail.aspx?qs=rsHPD1Ud3U45bB7MnDGbLQ%3d%3d

TL783 - is this one correct?
http://www.newark.com/texas-instruments/tl783ckcse3/linear-regulators/dp/10M0615

78S12 - is this one correct ?
http://www.newark.com/stmicroelectronics/l78s12cv/voltage-regulator-ic/dp/89K0776?_requestid=243966

TIP121 - is this one correct ?
http://www.newark.com/jsp/search/browse.jsp?N=500003+1001808&Ntk=gensearch_001&Ntt=TIP121&Ntx=

  and the lorlin switch's - use silver, Gold plated or Gold Flash ?

  Any and all help greatly appreciated,

                Thanks ,
                          Chip

This isn't a bom for the G-9. But here is the Mouser order I made back when I built my G-9. It should have all the parts I needed from Mouser for my G9. But probably has a few items for other projects also. But not many. Maybe it can answer a couple of your questions.

I did also order some parts from Farnell, triode, and digikey etc. tho...

www.stagefrightrecords.com/G9.rtf

And Gyraf has the parts list on www.gyraf.dk It lists the voltages for the caps.

Hope it was some help. Hope you have a great build!!

John

Hi John,

      Thanks so much, that answered a lot of them.

I am going by Gyrafs list, but am having difficulties finding the right values for some of the parts listed, and also because of my Newbie-ness  ;D

  Output Level pot  -  47k (Log) pot - logarithmic/inverse/linear - carbon/conductive plastic - there's so many different types

  Need voltages for, C8,108 - C9,109 - there is no listed voltages on Gyrafs list

  D3,D4,D5, - ZD39 - any suggestions ? - link to the only .5w mouser lists - not sure if the voltage is correct
http://www.mouser.com/Search/ProductDetail.aspx?qs=DHPsj9PSUngBff3BfOGZhA%3d%3d

  Thanks again,
                  Chip


 


   

 

 

I'll try to help ya best I can If ya can gimme a little to check parts orders. And BE VERY SAFE. There are HIGH voltages in there when ya get done. Best to have 2 meters. 1 on the high tension line. So you can see when it is safe and one meter to check other stuff like heaters or phantom etc. Leave the high one on ALL the time. Be back in a bit lemme look... The bom I used went down. And wasn't correct anyway. The diodes are listed in my Mouser order somewhere... Type zd39 into mouser search engine... For cross reference.

Think the diodes are this  526-NTE5086A. And the c8/108 and c9/109 are for the high pass filter. Get anything. I think I used wimas for accuracy. But totally unnecessary. Don't think voltage is much a problem on them...  But I may be corrected soon. LOL

Digikey and Farnell suck at histories sorry that is all I got.

You can buy a 47k log pot anywhere. And try not to be a newbie with tubes! Just be careful.

Hi,

  John,
          Thanks so much for the help and advice, I've read it in hear many time - " One hand in the pocket"

  I think I am all set for now, will post back on progress,

                                                                      Thanks again,
                                                                                        Chip

hey guys,

i am experimenting a bit with psu ...i have a toroid which is putting in 287 volts across the 470r is this too much for the tl783 to handle? my 470r keeps blowing up.

cheers
keith

resistors should not burn no matter what.

If you read through the circuit description, you'll notice that the in/out voltage difference for the TL783 voltage regulator circuit must be kept below 120V - so at 245V out, it should accept some 255 to 360V DC (but around 260 to 280 is ideal).

Remember - as mentioned several times earlier in this thread - that you can only measure voltages with tubes in-circuit and heated up.

Jakob E.

First post. My tech and I are about to embark on this project. We plan on doing 4 channels, 2 separate power supplies, VU meters and vintage knobs. For those of you who built this, what brand of tubes are you using and why? I was looking on tubedepot.com and they have a lot of ECC82's to choose from so any suggestions would be great.

I used JJ´s in mine... sounds just great

I have some old Jan specs-love them.

Hi All,

    A Little confused 
 

  On the Gyraf site it says:
                                      "For 110V mains, you'll need two 110+110:15+15V (30VA or larger) toroid transformers. The two first primaries - for mains input - should be coupled in parallel, for 110V. The two primaries of the second transformer should be connected in series, to bring voltage up to around 220Vac."

  but in the shoppig list it says:

                                  "OR - if you're in a 110V mains area:
First:    110+110:15+15V/ 30VA TOROID      PSU 220V mains to 15VAC
First:    110+110:12+12V/ 30VA TOROID      PSU 15VAC to 220VAC *note:updated!

  So.... which one is it?
                              Two 15v or one 15v and one 12v  ?


    I haven't read ALL the Metas, but I think I've read enough, and haven't read anything on this? 

  Sorry for,the Newbie-ness

                        Chip

where it says *note:updated! - we changed from two 15V transformers to a 15V and a 12V - to get voltages closer to what we want.

Jakob E.

Hi,
    Jakob, Thanks so much, and Thanks for Designing such an awesome project. I'm learning, and having a blast !

            Chip    ;D

I used NOS GE's Vintage mid 60's on mine from tubeworld.com and am very happy. They were also reasonably priced. I have also gotten other tubes from there for other projects and they all tested great on my tester and sounded just perfect. I think he listens to them if you tell him it is for a preamp. Nice guy.

audiophreak when you get this done and start using it you will say holy crap can't believe I built this. It's worth it and best of luck to you! My G9 is on right now. In use once again...

John

hi jakob ,
thanks for your reply , i am not even coming close to measure voltages as soon as i hit the switch on the 470r immediately burn out...im so confused ... i've checked all components ....do you have an idea what could cause this?

thanks

keith

edit : could it be the capacitors ? i am trying to test them but i do not have a propr capacitance meter...

Hmmm...
Never noticed that now we are using a 15v and 12 v transformer.  I just ordered two 15v torroids.  Does that just make the 78s12 run hotter?  I remember having problems with that before and having to get a really big heatsink, but all runs fine now after a few years with the two 15v torroids...

Cruious to know.
Thanks,
joel

Hi,
 
  Need some advice, I've noticed in pics of others G9s that the
  C3-103
  C4-104
  C5-105
  C7-107
  C10-110
  C13-113
 
  Polys were WIMAs, or what looks like Hovland Musicaps, or others I dont know the manufacturer of.

    Do these make a huge difference in the sound, I know that's very subjective, but am in the middle of the build and want to use the best components,

I have been looking at:

  TRT Dynamicaps/Wondercap, Hovland Musicap,Solen/Axon, and Jupiter beeswax and paper caps


  any advice or preferences appreciated,
      Thanks,
              Chip