The official G9 help thread

[gemini86]

Yes

 

[ibanman555]

Hey all,

This may have been asked already, but I can't search well... Which in your opinions, is a better transformer for the G9?? The Lundall or the OEP? Thanks in advance!

 

[gemini86]

The Lundahls are superior, but much more expensive. If you can afford them, I don't think you'll regret them.

 

[ibanman555]

Great thank you! I figured as much when I was pricing out all the parts, and found the Lundall's to be far more expensive, yes! You get what you pay for right?

 

[gyraf]

I agree - the Lundahl is expensive, but very very nice.

Jakob E.

 

[knight84]

Hi everyone, I am a very new DIY builder from Turkey. It is impossible to get the Lundahl's in the country. I sent an email to Farnell and learned that they dont supply lundahl anymore. Can you please give me suggestion from where I can get them easiest ?

 

[bruce0]

I will be in istanbul at the very end of august, the US distributor is K&K I think, may be others, you can look.

Long time to wait.

 

[gyraf]

In UK, Canford has some of them: http://www.canford.co.uk/Lundahl

Also, if there is no Turkish distributor, you can buy directly from Lundahl in Sweden.

Jakob E.

 

[spase]

Are you also using a "make before break" switch for SW2?
Maybe you can probe with a 10Meg scope for any DC offsets before and after the pop?

Yes... MBB but I modified BBM to make them that way, so maybe I screwed up.
Re: Probe prior... that is what I was planning, thanks

Can you give me some info about that modification...maybe some pictures.

 

[gemini86]

http://www.groupdiy.com/index.php?topic=51020.msg654764#msg654764

 

[spase]

Thank you.

 

[bruce0]

But again, my popping noise I was trying to cure was caused by microphonic tubes, and I only modified 1 of my modules, the rest I left as BBM with no ill effect.

 

[mrdarwin]

Hi!
I just finished my G9 preamp and I need help please!
The instrument input works perfect, on two channels.

But I've got some trouble with line/mic input...
I loose very much signal, like a low cut at 400Hz... On channel 2, 48V works and sometimes doesn't work... and big noise/hum on each channel.

I tried to bypass the relay, feed signal directly to OEP transformer, no change. It's strange because the input instrument is just after OEP and it works!..
I use OEP transformers input and output with screening cans. I'm sure at 99.9% I've put A3E on input and A2E on output.
I use Axicom Swiss relay C93402.

So if the someone has an idea...
Please tell me if the answers is on a page of the 70 of this thread, thanx.

And please sorry for my "french" english.

 

[braeden]

Hi!
I just finished my G9 preamp and I need help please!
The instrument input works perfect, on two channels.

But I've got some trouble with line/mic input...
I loose very much signal, like a low cut at 400Hz... On channel 2, 48V works and sometimes doesn't work... and big noise/hum on each channel.

I tried to bypass the relay, feed signal directly to OEP transformer, no change. It's strange because the input instrument is just after OEP and it works!..
I use OEP transformers input and output with screening cans. I'm sure at 99.9% I've put A3E on input and A2E on output.
I use Axicom Swiss relay C93402.

So if the someone has an idea...
Please tell me if the answers is on a page of the 70 of this thread, thanx.

And please sorry for my "french" english.

Is your 1/4" jack input a switching type?

When switching to 48V (on the rotary switch), connect your multimeter leads between pins 1&2, 1&3 and check that there is 48V at the input jack.

I think your problem lies somewhere around the line select switch (LINE-MIC-48V), but who knows with these things.

Braeden

 

[mrdarwin]

Thanx for the answers Braeden.
So, my input instrument on front panel is 1/4 switch jack but well wired (I think)
And my mic/line input on rear panel is a XLR connector.

I will try your exam and tell you. ( I couldn't work to G9 before wednesday...)

 

[mrdarwin]

Thanx for the answers Braeden.
So, my input instrument on front panel is 1/4 switch jack but well wired (I think)
And my mic/line input on rear panel is a XLR connector.

I will try your exam and tell you. ( I couldn't work to G9 before wednesday...)

So after quick measurement this morning, my 48V is sometimes 62,3V(!) on two channels, and sometimes works and sometimes not on channel 2...

 

[gemini86]

check out your wiring and correct parts in the 48V power supply section. Sounds like your voltage regulation is not working there. Double, triple check all your wiring, this is the biggest cause of problems. Also, did you do the DI wiring modification?

 

[mrdarwin]

check out your wiring and correct parts in the 48V power supply section. Sounds like your voltage regulation is not working there. Double, triple check all your wiring, this is the biggest cause of problems. Also, did you do the DI wiring modification?

I didn't check 48Vpsu yet.
A quick look to the datasheets of my Axicom MT2 C93402 relay and Jacob's preconised relay: when you look "over":

Axicom:
16    13  11  9
1      4    6    8


I don't know where is "+", datasheet says "2nd generation non polarized" (?)

Omron:
1      4    6    8
16    13  11  9

"+" is on pin 1

Do I have to change the relays with Omron likes?
Thanx

ps: I didn't do the DI wiring mod

 

[gemini86]

Well, the relays are identical.

some relays may have a built in diode across the coil to suppress voltage spikes when the coil is deenergized. The omron, as well as yours do not. That is good. So it won't matter if you swap the +- pins, but there's no way to actually do that, since it has to fit in the PCB.

Check:
1) wiring from the input transformer's secondary windings is correct. It should go from the transformer secondary to the instrument jack's normally closed pin (on the tip contact), then from the tip contact to C2. Look at the schematic for a clear view of what I mean.
2) Check out the 48V supply. 62V is much too high, and that's typically the voltage seen on the input side of the regulation, just after the voltage tripler.

after that's all good, then you can worry about the relay.

 

[mrdarwin]

Well, the relays are identical.

some relays may have a built in diode across the coil to suppress voltage spikes when the coil is deenergized. The omron, as well as yours do not. That is good. So it won't matter if you swap the +- pins, but there's no way to actually do that, since it has to fit in the PCB.

Check:
1) wiring from the input transformer's secondary windings is correct. It should go from the transformer secondary to the instrument jack's normally closed pin (on the tip contact), then from the tip contact to C2. Look at the schematic for a clear view of what I mean.
2) Check out the 48V supply. 62V is much too high, and that's typically the voltage seen on the input side of the regulation, just after the voltage tripler.

after that's all good, then you can worry about the relay.

Hi!

So problem solved for xlr input: wrong wiring instrument SWITCHING input...

and for 48VPSU: I ordered zener diodes PHC56 but Farne** *******14 sent me PH4148... thank you!
I'll try to find zener 56V and tell you soon.