The official G9 help thread
- Thread starter gyraf
- Start date
Help Support GroupDIY Audio Forum:
Hi folks,
I wiring up my G9. with regard to the 15v, 220v and 12v pcb connections. How do I determine which terminal is - or +??
Going by the schemo the terminals coloured red in the attached image are going to the top rail of the rectifiers. This conflicts with the hook up in Skylars diagram which is throwing me??? http://www.mediafire.com/view/mu6u0fz7780gx1p/G9Toroidconnections.jpg
I wiring up my G9. with regard to the 15v, 220v and 12v pcb connections. How do I determine which terminal is - or +??
Going by the schemo the terminals coloured red in the attached image are going to the top rail of the rectifiers. This conflicts with the hook up in Skylars diagram which is throwing me??? http://www.mediafire.com/view/mu6u0fz7780gx1p/G9Toroidconnections.jpg
Attachments
Harpo
Well-known member
These are VAC (voltage of alternating current) connections (symbol ~). After rectification these get + and - VDC (voltage of direct current) in respect to the other voltage rail.burglar said:
Thanks for your post Harpo,
I'm sorry, I'm explaining my problem badly. I am trying to determine which terminals the positive and the negative of the toroidal secondaries go to on the PCB respectively...
The secondaries on the toroids have a 0v connection & a Vsec connection http://www.spiratronics.com/data/1593.pdf
I'm puzzled as to which terminals they go to on the PCB. I guess 0v goes to the bottom of rectifier and vsec to the top?
I'm sorry, I'm explaining my problem badly. I am trying to determine which terminals the positive and the negative of the toroidal secondaries go to on the PCB respectively...
The secondaries on the toroids have a 0v connection & a Vsec connection http://www.spiratronics.com/data/1593.pdf
I'm puzzled as to which terminals they go to on the PCB. I guess 0v goes to the bottom of rectifier and vsec to the top?
Harpo
Well-known member
As previously said, these are AC connections. If one terminal is positive in respect to its other winding end for a specific moment in time, this will be just the other way round 1/50sec. or 1/60sec. later, depending on frequency of the local mains voltage of your location. (please update your profile with your location data.)burglar said:
They don't. This is just one way to express the start and end of a winding. (you might as well have noticed the dots...). Knowing these is essential for a windings series or parallel connection, F.I. in order to connect to local 115 or 230VAC mains or for creating a center tapped connection from series connected secondary windings.
..or just the other way round. Doesn't matter in this case.
Thanks for your post Harpo.....So,
on power up I have a very loud earth loop and the G9 is not passing audio. The tubes are glowing, i have panel light and the earth loop reacts to the gain switch and output pots. Here is a sound clip. BE CAREFUL! it gets loud as I go up through the gain settings and some of it is very high frequency. https://soundcloud.com/sdosuk/earth-loop
I am using these transformers: http://www.spiratronics.com/data/1593.pdf
2x 115v - 2x 15v & 2x115v - 2x12v both 50va. I am in the UK so both sets of 115v connections are in series. I soldered together the grey & the purple on both transformers.....
The red & black 15v sec is going to the heater
the yellow and orange 15v sec connections are joining the 12v secondary of the other toroid which is in parallel so, 15v yellow connects to 12v yellow & red. 15v orange connects to 12v orange & black. Pic attached.
I don't have the instrument jacks yet so I am powering up without them, not sure if this makes a difference?
I'd really appreciate some help with this. Hoping it's just a newb hook up error :L
B
on power up I have a very loud earth loop and the G9 is not passing audio. The tubes are glowing, i have panel light and the earth loop reacts to the gain switch and output pots. Here is a sound clip. BE CAREFUL! it gets loud as I go up through the gain settings and some of it is very high frequency. https://soundcloud.com/sdosuk/earth-loop
I am using these transformers: http://www.spiratronics.com/data/1593.pdf
2x 115v - 2x 15v & 2x115v - 2x12v both 50va. I am in the UK so both sets of 115v connections are in series. I soldered together the grey & the purple on both transformers.....
The red & black 15v sec is going to the heater
the yellow and orange 15v sec connections are joining the 12v secondary of the other toroid which is in parallel so, 15v yellow connects to 12v yellow & red. 15v orange connects to 12v orange & black. Pic attached.
I don't have the instrument jacks yet so I am powering up without them, not sure if this makes a difference?
I'd really appreciate some help with this. Hoping it's just a newb hook up error :L
B
Attachments
Harpo
Well-known member
Have a look at the schematic and wonder why signal doesn't make it from mic transformer to c2 without the switching input jack in between ? This as well causes c2 to be unterminated with one side hanging in the air, that most likely will be the cause of your "earth loop". A cranked guitar amp with plugged in guitar cable, but without the guitar connected will behave/hum the same...burglar said:
ok so all seems well now, just needs a tidy up and a front panel.
I'm using OEP's and this unit does seem light on the low end.
Did people get to the bottom of what the cause is?
Are there any mods to counter the roll off?
I'm using OEP's and this unit does seem light on the low end.
Did people get to the bottom of what the cause is?
Are there any mods to counter the roll off?
For some reason when powering a mic with 48v i get interference which varies from mic to mic and changes as I move the mic around. I have the control pcb's out of the case at the moment as I don't have a front panel. Moving the control pcb's position seems to affect the noise as well.
This does not occur without 48v. sound clips:
mic 1 - https://soundcloud.com/sdosuk/at-pncil-mic-48v?in=sdosuk/sets/48v-noise
mic 2 - https://soundcloud.com/sdosuk/mxl-mic-48v?in=sdosuk/sets/48v-noise
This does not occur without 48v. sound clips:
mic 1 - https://soundcloud.com/sdosuk/at-pncil-mic-48v?in=sdosuk/sets/48v-noise
mic 2 - https://soundcloud.com/sdosuk/mxl-mic-48v?in=sdosuk/sets/48v-noise
burglar said:
Changing noise when moving microphone points towards poorly shielded mic or very-noisy environment, not towards problem in P48
Not having the unit enclosed in shielding, it's impossible to judge noise and so. Finish the project with case and all before starting worrying about this.
Jakob E.
Ok thanks Gyraf,
I have quite severe bass roll off with my unit currently. I am using OEP in and out. From what I read in this instance it is best to swap input transformers for lundahl and leave OEP on output.
Is there anything else I should be doing or checking to counter this?
Cheers
I have quite severe bass roll off with my unit currently. I am using OEP in and out. From what I read in this instance it is best to swap input transformers for lundahl and leave OEP on output.
Is there anything else I should be doing or checking to counter this?
Cheers
Paperweight
Member
I was looking at Gyraf's own site for the G9 and printed off the shopping list to buy parts. On the parts total list there are 2 x 220k listed in the totals but I don't see them in the components list or the schematic. Any help would be appreciated. Sorry if this is a stupid question.
Edit: I see a 2002 schematic with R9 at 220k and a 2006 schematic with R9 at 47k. Is this where the mix up happened? I was wondering about the count of the 47k resistors (parts list says 8 ) being short by 2 according to the board. You might want to fix that for future reference. I can't believe that's been like that for 10 years.
Edit: I see a 2002 schematic with R9 at 220k and a 2006 schematic with R9 at 47k. Is this where the mix up happened? I was wondering about the count of the 47k resistors (parts list says 8 ) being short by 2 according to the board. You might want to fix that for future reference. I can't believe that's been like that for 10 years.
Stagefright13
Well-known member
Well my G9 that Gyraf was kind enough to let us build rocks totally. Been using it for years. So long in fact that the lorin switches are getting scratchy. I had A producer hear that... I said sorry old tube pre. He said I wanna use that! And loved it. Made great CD. Thanks Gyraf!
Hi everyone,
I use the Don Audio's special trafo for G9. I've just wired it but I found 320V instead 245V for HT, 35V instead 12V and I can't reach 48V for the phantom power (got 42V).
These values are without load, no tubes and no mic in input too. I'm afraid of putting tubes with these values...
Someone used the same trafoin this tread don't spoke about the values...
I wish he could help me (or someone else
)
Thanks!!!
I use the Don Audio's special trafo for G9. I've just wired it but I found 320V instead 245V for HT, 35V instead 12V and I can't reach 48V for the phantom power (got 42V).
These values are without load, no tubes and no mic in input too. I'm afraid of putting tubes with these values...
Someone used the same trafoin this tread don't spoke about the values...
I wish he could help me (or someone else
)Thanks!!!
As mentioned a couple of times earlier in this thread (please read it), you can't measure voltages without tubes in circuit.
Jakob E.
Jakob E.
Paperweight
Member
A variac would be the ideal solution to this situation. Have a volt meter monitor the high tension with tubes in place and slowly adjust the variac up to full outlet voltage.
So, I've finished and closed up my unit. I am waiting on some JJ tubes. I have a hand full of old ecc82 here that my grandad gave me but they are untested. Having tried all of them, the configuration makes little to no difference to the symptoms.
I am experiencing high noise floor and fairly low output considering the G9 is maxed out in this test. Listen to the G9 condenser clip. There is some interference in the noise floor switching frequency. The lid is on and sealed. I have not done the trace mod, and I am close to monitor, computer, etc. For grounding I have just connected all earth tags on my XLR connectors and joined pin 1 of input 1 to the star point ground by the IEC.
There is quite severe bass roll off as you can hear in comparison to the audient preamp. I am using OEP transformers in and out.:
https://soundcloud.com/sdosuk/g9-comparison/s-igN03
I am experiencing high noise floor and fairly low output considering the G9 is maxed out in this test. Listen to the G9 condenser clip. There is some interference in the noise floor switching frequency. The lid is on and sealed. I have not done the trace mod, and I am close to monitor, computer, etc. For grounding I have just connected all earth tags on my XLR connectors and joined pin 1 of input 1 to the star point ground by the IEC.
There is quite severe bass roll off as you can hear in comparison to the audient preamp. I am using OEP transformers in and out.:
https://soundcloud.com/sdosuk/g9-comparison/s-igN03
Hi,
at this point I have my 240V for HT.
I've found some twisted wires on the instrument input and got some sound.. I've put my bass in and got a very distorded sound and i've to put the two level at the maximum to heard something...
By the way, the mic input doesn't works but I keep the faith
at this point I have my 240V for HT.
I've found some twisted wires on the instrument input and got some sound.. I've put my bass in and got a very distorded sound and i've to put the two level at the maximum to heard something...
By the way, the mic input doesn't works but I keep the faith
