The official G9 help thread

[johnchantler]

Thank you for this info and reassurance.

It powers up fine and with power applied it no longer shows any continuity between 12V/0V.

Both channels now sounding great, too — just a noisy DI on Ch 2. not so bothered for now as will mostly use mic/line inputs. Will have another look when I have time/energy to open it up again.

Jakob — Thanks so much for making this project possible!

 

[rockinrudeingo]

Hi Godders,
i don't think it's a grounding issue, cos it's there even if i lift ground completely, anyway heres my grounding, i know it's hard to see, but there's the green/yellow-wire coming from the IEC-Inlet to pin 1 on the XLR-F from there a black wire to chassis ground and one to pin 1 XLR-F (channel 2) from there a black wire to pin 1 XLR-M (channel 2) and one from pin 1 XLR-F (channel 1) to pin 1 XLR-M (Channel 1). From the XLR-F 's ground goes to Mainboard. the XLR-M (output) don't go on the board yust shielding the wire...

thanks ev'ryone
tschau Ingo

hi! today i finally solved the issue. now i have a totally hum free g9! isn'nt that a thing!
Beitrag im Thema 'Gyraf G9 Stereo Röhren Micpreamp' Gyraf G9 Stereo Röhren Micpreamp

 

[lightningbefore]

Hello, does anyone have a recent bom cart for this they’d be willing to share?

 

[TillM]

hi! today i finally solved the issue. now i have a totally hum free g9! isn'nt that a thing!
Beitrag im Thema 'Gyraf G9 Stereo Röhren Micpreamp' Gyraf G9 Stereo Röhren Micpreamp

thanks for the link !
As a German, I never think about searching on a German site.
My Gyraf was quite but the second channel always had lower volume (like 3-4db).
After that modification booth channels have the same output.

 

[Clbraddock]

Is there a good alternative for the TL783? I can't find any and it sounds like there might not be any more except surface mount.

 

[gyraf]

I have NOT heard any rumors of the TL783 in TO-220 going obsolete..? Can you point to a source for this?

There's no real alternative, so it's quite dramatic if really discontinued

/Jakob E.

 

[Clbraddock]

This thread is what came up when I searched for TL783 substitute:

https://groupdiy.com/threads/instead-of-tl783s.6038/
Information could very well be wrong though. I just saw that no one had them in stock and then that thread mentioned being discontinued, except surface mount. That said, I didn't realize that that thread was from 2005 when I looked at it. I've bought TL783s since then. So, probably the thread is wrong and they are just out of stock.

 

[gyraf]

Yes, that was a scare we had some 17 years ago - turned out to be the design not entirely predictable enough for medical electronics, but was "re-issued" as a not-for-critical category device.

I have not heard about trouble since then?

 

[Brian Roth]

I hope I have some in stock, since it seems like the usual distributors have orders pending, with delivery NEXT YEAR! My backup for oddball parts, Jameco.com, has nothing. A web search found a "scalper" website selling them for $34 IIRC.

Bri

 

[Brian Roth]

We should start a new thread re. TL783 so the discussions don't clog this thread.

Bri

 

[jamierichards7]

Hi, I'm trying to revive 2 G9 builds I started several years ago as I now have a little more time to finish them..

I'm just wondering - Looking at the Gyraf site, the main page says I need 2 x 220v/15+15v power transformers, but the shopping list says I need one 220v/15v+15v and one 220v/12v+12v.

Could someone please clarify which I need to buy?

Thanks!

Jamie

 

[jamierichards7]

Hi, I'm trying to revive 2 G9 builds I started several years ago as I now have a little more time to finish them..

I'm just wondering - Looking at the Gyraf site, the main page says I need 2 x 220v/15+15v power transformers, but the shopping list says I need one 220v/15v+15v and one 220v/12v+12v.

Could someone please clarify which I need to buy?

Thanks!

Jamie

Ah just looked at the schematic and it has 220/12v+12v as the second one so I guess I'll go with that

 

[Clbraddock]

What is the best way to separate the pcb boards (the power supply board and front panel boards)? Do you just cut them with an exacto knife?

 

[johnchantler]

I used a dremel.

 

[Clbraddock]

@Deepdark

Thanks for sharing your mouser cart. It seems like a great starting point for sourcing the parts. One question: I noticed a handful of carbon film resistors. Did you choose those over metal film for tone or for cost savings?

 

[gyraf]

..no tone in resistors..

 

[Clbraddock]

..no tone in resistors..

I was under the impression that carbon composition had voltage coefficient of resistance meaning that as the voltage changes, so does the resistance. In effect this causes distortion. The only place I'm aware with voltage swings large enough to make a difference with voltage coefficient is basically the plate resistor though. Is this not accurate?

 

[lightningbefore]

@Deepdark @Clbraddock would you mind sharing the Mouser cart with me? I've been looking through the thread and can't find it.

 

[Clbraddock]

Here is Deepdark's https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=0bb030cf12

Here is mine (I subbed for some items that were no longer available. I couldn't sub for everything that was unavailable though, so some stuff I just deleted. Therefore, Deepdarks is more complete but also has more out of stock) https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=fd889a7026

Edit: With either cart there are still other items you will need, such as transformers etc. This is just a good starting place for most of the generic parts.

Edit2: Also be aware that some ICs like TL783 are out of stock until 2023 before you order the cart. I didn't realize the lead time was quite that long when I started. I might end up trying my hand at making a discrete voltage regulator.

 

[lightningbefore]

Thank you, that's so helpful! I'm not in a rush so 2023 is fine - I have a big backlog to build in the meantime but want to get the ball rolling on this one any way possible. Much appreciated!