Smoke

Some G9 questions
« on: November 17, 2004, 08:37:57 PM »
These may sound a bit lame to the pro's, but oh well I have to learn.

1) The G9 project uses some 1N4001 diodes, specifically D2 and D8-D16. I have a pack of 100x 1N4007, could I replace the 1n4001 with 1n4007? As far as I understand it the 1n4007 can take up to 1000v and 1n4001 100v, and some of those diodes should protect greater voltage going through so it probably wouldnt be appropriate.

2) This may be silly, but how do you "SET" a rotary switch, specifically 12 position to 11 and 3 pos to 2 (PHASE G9)?

3) can someone please give me more details on the relays... i went to my local Jaycar Electronics and the people there didn't know what a "12V 2xCO RELAY" is.  A possible RS components or farnell part number would be appreciated

4) I would like to be more educated about the second 15v to 245v toroid transformer... Why do we convert 220v to 15v, then the 15 back to 220v? Is that inefficient and power-draining? and wouldn't it be cheaper to skip the 15v to 220v transformer and take 220vac from the mains into the D17-D20 1n4007 diodes? What would the drawbacks be if possible at all?there must be a reason and i really want to know (:

Thanks all.


mcs

Re: Some G9 questions
« Reply #1 on: November 17, 2004, 08:46:16 PM »
Quote from: "Smoke"
could I replace the 1n4001 with 1n4007?

Yes, use whatever type you have

Quote
This may be silly, but how do you "SET" a rotary switch, specifically 12 position to 11 and 3 pos to 2 (PHASE G9)?

The Lorlin switches have a small ring on top you can turn to set the number of positions you want.

Quote
can someone please give me more details on the relays...

You need a 12V DIL-relay. A common type is the Omron G5V-2, but they are made by most/all relay manufacturers.

Best regards,

Mikkel C. Simonsen

bluebird

Some G9 questions
« Reply #2 on: November 17, 2004, 08:52:04 PM »
Yes you can use 4007's instead of 4001's.

to set the rotory switch you have to open the switch up and move the internal washers with the small tabs so the switch only moves as many space as you want.

I believe the relays are 12 Volt double pole double throw or DPDT. so there are actually two switches per relay...these are very common.

Smoke

Some G9 questions
« Reply #3 on: November 17, 2004, 08:58:46 PM »
thanks guys I'll stick in the 1N4007's, i'm still worried about that D2 though. I hope everything is ok.

Yeah i found the metal plate for the switch positions, pretty cool.

I also updated my questions (: any knowledge sharing on the transformer question?

This forum is great there's ppl on 24/7 (:

mcs

Re: Some G9 questions
« Reply #4 on: November 17, 2004, 09:46:22 PM »
Quote from: "Smoke"
and wouldn't it be cheaper to skip the 15v to 220v transformer and take 220vac from the mains into the D17-D20 1n4007 diodes? What would the drawbacks be if possible at all?there must be a reason and i really want to know (:

If you have plans to kill someone - go for it! :wink:

Best regards,

Mikkel C. Simonsen

tubejay

Re: Some G9 questions
« Reply #5 on: November 17, 2004, 09:58:13 PM »
Quote from: "mcs"
Quote from: "Smoke"
and wouldn't it be cheaper to skip the 15v to 220v transformer and take 220vac from the mains into the D17-D20 1n4007 diodes? What would the drawbacks be if possible at all?there must be a reason and i really want to know (:

If you have plans to kill someone - go for it! :wink:

Best regards,

Mikkel C. Simonsen


Can you explain that a little more?  Is it an amps thing or something???  I'm a real dullard with this stuff.

mcs

Some G9 questions
« Reply #6 on: November 17, 2004, 10:21:14 PM »
If you power an amp directly from the mains, the chassis will be connected to the mains. So touching it (or anything connected to it) will be unpleasent...

The old transformer-less radios and TVs had isolated chassis and everything connected to the outside going through safety transformers and safety caps (often with a 5kV rating). Even if you isolated the ground in the G9, the small OEP or Lundahl transformers are NOT safety transformers.

And working on a mains-powered circuit is dangerous - the limited current from a small transformer is safer.

Best regards,

Mikkel C. Simonsen

Smoke

Some G9 questions
« Reply #7 on: November 17, 2004, 10:37:37 PM »
as far as I understood this, theres a higher risk of having high current through the circuit, and a the 220v to 15, then 15 to 220v transformer system sorts that stuff out.

The only part i cant understand is the chassis connected to the mains... the only thing connected to the chassis is the ground.
What am I missing?

Smoke

Some G9 questions
« Reply #8 on: November 17, 2004, 10:45:56 PM »
I have a capacitor question.

is it always ok to place a larger voltage capacitor than the required?

In my case, the G9, C8 and C9 i have 10nF and 22nF both 100V, are those ok and will they have a (negative) effect on sound?

thanks

zebra50

Some G9 questions
« Reply #9 on: November 18, 2004, 03:53:28 AM »
Higher voltage caps will be fine - just use what you have.

I do recall there was a discussion here (or elsewhere) about the thickness of the dielectric making some kind of sonic change, but I don't think there were any firm conclusions.
Ribbon microphone services
http://www.xaudia.com
Microphone blog


Smoke

Some G9 questions
« Reply #10 on: November 18, 2004, 04:31:58 PM »
I actually figured out that power transformer question thing (with some reading).

This first 220v to 15v acts like an isolator from the mains circiut. It reduces the voltage, but also drastically reduces the current. when you convert it from 15v to 220v that new 220v is not as lethal as the 220 from the mains. Theres a less greater chance that 220v will kill you, but don't try it!

someone correct me if im wrong, or add something (:

dukasound

Some G9 questions
« Reply #11 on: November 19, 2004, 05:41:43 AM »
Hi
Does anyone knows exactly position of Gain switch in db?
Thanks
Duka
I am waiting for some caps and chassis and it will be finish :roll:

gyraf

Some G9 questions
« Reply #12 on: November 19, 2004, 05:47:43 AM »
Quote from: "dukasound"
Does anyone knows exactly position of Gain switch in db?


No, I haven't measured that. The steps are around 4dB - as close as standard values allows.

With the continous output level control, marking the input gain in dB's wouldn't make sense in absolute terms.

Jakob E.
..note to self: don't let Harman run your company..

dukasound

Some G9 questions
« Reply #13 on: November 19, 2004, 05:54:06 AM »
Quote from: "gyraf"
Quote from: "dukasound"
Does anyone knows exactly position of Gain switch in db?


No, I haven't measured that. The steps are around 4dB - as close as standard values allows.

With the continous output level control, marking the input gain in dB's wouldn't make sense in absolute terms.

Jakob E.


Ok. What can be max gain?
Thanks (like allways)
Duka

gyraf

Some G9 questions
« Reply #14 on: November 19, 2004, 06:04:44 AM »
max gain around 60dB, I think
..note to self: don't let Harman run your company..

dukasound

Some G9 questions
« Reply #15 on: November 19, 2004, 06:33:22 AM »
Quote from: "gyraf"
max gain around 60dB, I think


Thanks

Smoke

Some G9 questions
« Reply #16 on: November 20, 2004, 06:00:25 PM »
just another question,
is a metal film 1/4watt 1% resistor considered as a precision resistor?
(the 6k8 R1 and R2 in G9)
Im using these for all my resistors.

AudioJunkie

Some G9 questions
« Reply #17 on: November 20, 2004, 10:42:35 PM »
Quote from: "Smoke"
just another question,
is a metal film 1/4watt 1% resistor considered as a precision resistor?
(the 6k8 R1 and R2 in G9)
Im using these for all my resistors.



I think that's fairly close precision.  Though i've seen some makers offer as much as .1% tolerance.  I usually buy 1% in multiples of 10 and match in pairs.  Usually can get as close as .1% that way.

Daniel

gyraf

Some G9 questions
« Reply #18 on: November 21, 2004, 05:34:49 AM »
But yes, 1% is all you'd really need for the phantom 6K8's. Higher precision will give you less annoying clicks when switching phantom on and off though..

Jakob E.
..note to self: don't let Harman run your company..

Smoke

Some G9 questions
« Reply #19 on: November 22, 2004, 12:27:58 AM »
i thought i migh ask this
Kev's page has a photo of Jacobs prototype.
http://recording.org/users/kev/G9_tube_micpre.htm

the INPUT switch has for options, inst, line, mic, 48v
while the front panel on Jacob's site, has 3 options, missing the inst.

However they start from 1 o'clock instead of 12 o'clock. Can someone explain this a bit more.

Thanks


 

Related Topics

  Subject / Started by Replies Last post
38 Replies
8447 Views
Last post December 14, 2005, 01:46:03 AM
by hejsan
13 Replies
1876 Views
Last post September 08, 2005, 09:12:58 AM
by Emperor Tomato Ketchup
3 Replies
1212 Views
Last post November 12, 2005, 09:14:12 AM
by maxime
1 Replies
992 Views
Last post July 20, 2007, 01:09:37 PM
by drpat