The official G9 help thread

[burglar]

Are you sure that I need just one of these for the build?  The specs on the site seem to keep changing, now it is saying one of the secondary's is 15v?

https://www.don-audio.com/G9-Audio-Power-Trafo-Sec-230V-15V-12V-Integrated-Shielding

 

[Harpo]

Are you sure that I need just one of these for the build? 

One transformer for a dual Gyratec IX micamp. No additional stepdown/stepup for the 230VAC secondary hv winding required.

The specs on the site seem to keep changing, now it is saying one of the secondary's is 15v?

Sometimes parts improve and/or are made closer to the goal, maybe it only was a typo correction. Don would know best what he offers.

 

[JingleDjango]

burglar I think I understand your confusion. Jakob's documents call for two transformers, one feeding the other, to get the different power rails. The particular transformer you're looking at has all of the appropriate secondary windings so that you only need to use one. Does this help?

 

[burglar]

Yes, thank you, I see now.  The 15v sec goes to D13 / 16 and the 230v sec goes to D17/ 20.  The 12v secondary will be unused?

 

[JingleDjango]

I'm actually not familiar with this particular transformer. I used the same combination as Deepdark suggested above, with great results. You do need a 12v rail for the filament heaters, though. I think that's what you're looking at.

 

[burglar]

I see, I'm not seeing that coing from either transformer on the schemo.  Am I being blind?!

 

[JingleDjango]

I believe the schematic still reflects the original 2x15V setup, whereas the updated components list recommends 15V for the 48V current source and 12V for the heaters.

EDIT:  Actually the schematic I have saved is Rev#8 and it reflects the change to 12V. Someone else may be able to explain this better.

 

[Harpo]

Yes, thank you, I see now.  The 15v sec goes to D13 / 16 and the 230v sec goes to D17/ 20.  The 12v secondary will be unused?

No.
The higher current 12VAC sec for the heaters goes to D13...D16 (BR2 from schematic),
the 230VAC sec goes to D17...D20 (BR1 from schematic),
the 15VAC sec for the tripler in order to get phantom +48VDC goes to D8, C26, C29, ...

 

[burglar]

Hi Guys,

On the PCB, the 10k trimmer seems to have 5 terminals?  I've not seen a pot that requires this pin out so which ones am I using?

 

[Deepdark]

In fact it has 3 terminals, but include 2 footprint to accomodate both casing.

 

[JingleDjango]

burglar, here's a bundle of images of different implementations of this project. They're culled from this thread. You might find them a helpful guide in selecting parts and organizing your build.
http://gardensound.ca/hotlinks/groupdiy/G9_Pics.zip

 

[burglar]

Spot on, thanks to you  both

 

[burglar]

So chaps, I have another question.  I'm about to buy a couple of power transformers.  Do they need to be rated 30va for 15va per winding?  Or do I need60va for 30va per winding?  If so, do I need that spec on both transformers. 

I did see some discussion about this whilst reading the thread but I cant seem to find it now.  The closest I can get to the latter is 80va for 40va per winding?

 

[gyraf]

you'll need some 30VA for each transformer - not for each winding

 

[Deepdark]

The transformer I used are rated 50VA. probably over rated but it works fine and aren't expensive 

 

[JingleDjango]

Could someone please point me to their preferred lamp/holder for the pilot light? I haven't seen any appropriate 12v bulbs in the electronics shops nearby.

 

[dribro]

Maybe Banzai ?http://www.banzaimusic.com/Jewel-Full-Assembly-Amber.html

You'll have to measure voltages as this is a 6.3v bulb. Or maybe fit the right 12v bulb

 

[gyraf]

I've seen these used: Monacor 02.0350 "SB-6/WS" - it's a 6V bulb, so it takes a series resistor to run on 12V.

Jakob E.

 

[mihailojocic]

Hello good people!

My G9 have more than few years of hard work, so probably I should change my JJ electronics.

Can you please suggest me some good tubes but not to expensive!

I don't like theory to much, so if you have real experience with different tubes and differences between them (noise, sound etc., specially if it is significant) please write your thoughts.

thanks in advance
Mihailo

 

[burglar]

So Folks,

I am about ready to start wiring this badboy up.  I have a couple of questions:

- Is there a wiring diagram for the instrument jack?  If not, could someone explain the hook up in some detail?

- I am using the switches from diy valves sold specifically for this project.  How do I orient the 3 pos switches?

- My grandad kindly gave me x2 Mullard ECC82.  Where to use these (assuming they sound good) for maximum effect.  Both on output?

Cheers!

B