Rob Flinn
Well-known member
The switches will operate the relays without the leds connected up. The switches are 2 pole & one of the poles operates the relay & the other pole turns the led on.
API 312 Thread!
- Thread starter fallout
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Help Support GroupDIY Audio Forum:
robomatique
Well-known member
If you are using Fabio's boards and want to use the OEP input traffo, these are the changes you have to make (thanks Joe at JLM!).
Maybe you all knew, but for me that info was very important and appreciated!
One more question. If using an "original" sowter input traffo, should I mount RL?
Here is Fabio's Schematic:
http://www.thediypill.phx.com.br/forumfiles/R312sch_rev3.pdf
And the original from sowter site:
http://www.waltzingbear.com/Schematics/API/API_312.JPG
Thanks!!!
Robert
Maybe you all knew, but for me that info was very important and appreciated!
One more question. If using an "original" sowter input traffo, should I mount RL?
Here is Fabio's Schematic:
http://www.thediypill.phx.com.br/forumfiles/R312sch_rev3.pdf
And the original from sowter site:
http://www.waltzingbear.com/Schematics/API/API_312.JPG
Thanks!!!
Robert
pmroz
Well-known member
... still confused about 2*5*2*0 BC GND connection.
On BC board layout, there is a blue dot.
On opamp schem , i can't see the GND connection anywhere... but..
... on pre schem gnd is on loop with V-, 100n etc.
So it must connect to something? What goes in the hole next to GND pin?
Going to read more Pass and Self, etc... any help thanks
On BC board layout, there is a blue dot.
On opamp schem , i can't see the GND connection anywhere... but..
... on pre schem gnd is on loop with V-, 100n etc.
So it must connect to something? What goes in the hole next to GND pin?
Going to read more Pass and Self, etc... any help thanks
the GND on the opamp board is used for 100n caps between +v gnd and -v gnd.
I'm fitting mine under the board. This GND is also used by the original maker to shield the opamp, I have been told about some unetched board connected to GND over the opamp board.
Someone said that a metalic case grounded around the opamp is a good idea...
I think the empty GND hole was for the shielding...
:guinness:
Fabio
I'm fitting mine under the board. This GND is also used by the original maker to shield the opamp, I have been told about some unetched board connected to GND over the opamp board.
Someone said that a metalic case grounded around the opamp is a good idea...
I think the empty GND hole was for the shielding...
:guinness:
Fabio
pmroz
Well-known member
Fabio, thanks for the quick reply.
BTW wiring is too messy to relay spots, i'm going for relays...
This is just too much fun... thanks agin
So CD1 and CD2 mounted on pre-board take care of this. I wondered why those were on both the opamp parts and pre parts lists. Tracing the tracks i see what you're saying.
Cool... gotta figure a case/ shield for these still. Anybody know a source for correct size little black boxes... jewelry etc.?I think the empty GND hole was for the shielding...
BTW wiring is too messy to relay spots, i'm going for relays...
This is just too much fun... thanks agin
dukasound
Well-known member
Hi Fabio
Any informations about RL, RC, CC with OEP transformer.
I need it for ordering parts.
Thanks
Duka
Any informations about RL, RC, CC with OEP transformer.
I need it for ordering parts.
Thanks
Duka
dukasound
Well-known member
[quote author="Bauman"]Duka,
back a little bit
http://www.groupdiy.com/index.php?topic=68977#68977
or here at this page
http://www.groupdiy.com/index.php?topic=69334#69334
:thumb:[/quote]
Thanks Fabio, but here are different solutions.
On second link stay "For the OEP A262A3E RL = 27k and RC & CC should not be fitted as they are not needed".
Best
Duka
back a little bit
http://www.groupdiy.com/index.php?topic=68977#68977
or here at this page
http://www.groupdiy.com/index.php?topic=69334#69334
:thumb:[/quote]
Thanks Fabio, but here are different solutions.
On second link stay "For the OEP A262A3E RL = 27k and RC & CC should not be fitted as they are not needed".
Best
Duka
alo
how are your api going?.
well,mine still do not work,but since one of my doubts were the 1731,just to make sure these were okay,i put them in my jlm99v,and they worked just fine with +-15v.
so the problem i have it is in the boards,but i just do not know where.
best regards
pedro
how are your api going?.
well,mine still do not work,but since one of my doubts were the 1731,just to make sure these were okay,i put them in my jlm99v,and they worked just fine with +-15v.
so the problem i have it is in the boards,but i just do not know where.
best regards
pedro
Greg
Well-known member
hey Fabio:
I've got one of boards completely up and running... mic and line inputs... all works well. But I did notice one small problem with the phantom power. When I first turn on the circuit with phantom power "off", everything is fine. Then I turn phantom power "on", and I get my 48VDC. Then I turn phantom power "off", and the phantom voltage is hanging up in the 40VDC range for a really long time and slowly discharges. At the switch, I don't have any phantom, but at the mic input I do. So I'm guessing the CPP is not discharging properly. I think I put a 200R for RPP3... is RPP3 a bleed resistor? Are you having similar behavoir on your boards?
I've got one of boards completely up and running... mic and line inputs... all works well. But I did notice one small problem with the phantom power. When I first turn on the circuit with phantom power "off", everything is fine. Then I turn phantom power "on", and I get my 48VDC. Then I turn phantom power "off", and the phantom voltage is hanging up in the 40VDC range for a really long time and slowly discharges. At the switch, I don't have any phantom, but at the mic input I do. So I'm guessing the CPP is not discharging properly. I think I put a 200R for RPP3... is RPP3 a bleed resistor? Are you having similar behavoir on your boards?
chrissugar
Well-known member
Hey Greg,
I looked at Fabio's schem and there is normal what you describe because CPP1 is charged even if the relay disconects the 48V power. Rpp3 is not conected when phantom is disabled so it is has no role in discharging CPP1.
chrissugar
I looked at Fabio's schem and there is normal what you describe because CPP1 is charged even if the relay disconects the 48V power. Rpp3 is not conected when phantom is disabled so it is has no role in discharging CPP1.
chrissugar
Greg
Well-known member
Then perhaps a bleed resistor should be added to discharge CPP1... I wouldn't want to hit a ribbon with phantom?!?
What do you think?
Also, I don't think a relay is involved with the PP, just the PAD, POL, LINE, and HIZ.
What do you think?
Also, I don't think a relay is involved with the PP, just the PAD, POL, LINE, and HIZ.
chrissugar
Well-known member
Sorry I'm not too familiar with this schem, now I see that there is no relay for phantom [it is because in my projects I use relays for all the functions].
One solution to discharge the CPP1 is to do some changes. Exchange the conections between RPP3 and PWR48 at switch 1A [ I mean conect the CPP1resistor to where is conected PWR48 and conect PWR48 to where is conected RPP3]. Also conect the unused pin of switch 1A to ground.
Now when the switch is on, RPP# goes to 48V.
When the Switch is off, RPP3 is conected to ground so CPP1 will discharge.
chrissugar
One solution to discharge the CPP1 is to do some changes. Exchange the conections between RPP3 and PWR48 at switch 1A [ I mean conect the CPP1resistor to where is conected PWR48 and conect PWR48 to where is conected RPP3]. Also conect the unused pin of switch 1A to ground.
Now when the switch is on, RPP# goes to 48V.
When the Switch is off, RPP3 is conected to ground so CPP1 will discharge.
chrissugar
Hi Greg,
true. no extra bucks in PP relay needed
The thing is the capacitor will keep some charge for some time, I was not aware it was an issue since I used to turn off the phantom before I disconnect the mic, then the mic bleeds the PP out the cap... : :wink:
you can do this: do not use the PP LED where it was supposed to be but connect it in the PP
going to the input connector. raise the the led resistor to 5k1 at least. it will turn on when the power is on the way to the input connector and will drain the charge when the PP is turned off...
:guinness:
Fabio
true. no extra bucks in PP relay needed
The thing is the capacitor will keep some charge for some time, I was not aware it was an issue since I used to turn off the phantom before I disconnect the mic, then the mic bleeds the PP out the cap... : :wink:
you can do this: do not use the PP LED where it was supposed to be but connect it in the PP
going to the input connector. raise the the led resistor to 5k1 at least. it will turn on when the power is on the way to the input connector and will drain the charge when the PP is turned off...
:guinness:
Fabio
chrissugar
Well-known member
Yes, it is a good solution to use the led to discharge the capacitor.
chrissugar
chrissugar
Greg
Well-known member
I compared the MM-990 to the Melcor 1731 today... VERY different sounding opamps. I will be trying API opamps tomorrow. These preamps are awesome. Now that I know they work, it's time to get these racked up and presentable. :thumb:
chrissugar
Well-known member
"I compared the MM-990 to the Melcor 1731 today... VERY different sounding opamps. "
Hey Greg, if you use the API ouput transformer the test is not valid because the Millenia 990 is not capable to drive low impedance output transformers . If you want to hear the real diference between the two opamps you should test them without the transformer.
chrissugar
Hey Greg, if you use the API ouput transformer the test is not valid because the Millenia 990 is not capable to drive low impedance output transformers . If you want to hear the real diference between the two opamps you should test them without the transformer.
chrissugar
Greg
Well-known member
I emailed John at Millenia and asked him if the MM-990 could drive that tranny (I even did tell him the primary impedence), and he said yes. But I do agree with you that his opamps are probably not the best match in an API 312 preamp. I have other plans for the pair I got from him... :wink:
btw - I bought my tape machine from John.
btw - I bought my tape machine from John.
Hey Greg!
Got my 4 in a 1U finally wired and something bad is going on.
I have connected the 7805 to the R1/C1 point and with PAD and INVERT relays on in the 4 APIs, the regulator drops out. I mean, I think it gets hot and go to 0V.
With some heatsink on it gets better but after a while, it drops out again...
So 1 psu for each 2 channels is the best way to go.
(still working around this cos I don´t have room now for another PSU board :S)
cheers!
Fabio
Got my 4 in a 1U finally wired and something bad is going on.
I have connected the 7805 to the R1/C1 point and with PAD and INVERT relays on in the 4 APIs, the regulator drops out. I mean, I think it gets hot and go to 0V.
With some heatsink on it gets better but after a while, it drops out again...
So 1 psu for each 2 channels is the best way to go.
(still working around this cos I don´t have room now for another PSU board :S)
cheers!
Fabio
