No secrets here, I used transparent foil for overhead projectors.
PRR-176 Vari-Mu REV 2 - *Group Buy 7/13!*
- Thread starter abechap024
- Start date
Help Support GroupDIY Audio Forum:
Edward
Well-known member
Do I ground the PSU pcb from pin 4, which is the CT? Is that the only connection to ground needed from the pcbs?
with vu meter I can not get a correct reading of the compression
this might work?
Thanks
http://www.ebay.it/itm/PM-2-1MA-MOVING-COIL-METER-1MA-/130753131630?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item1e717e746e
this might work?
Thanks
http://www.ebay.it/itm/PM-2-1MA-MOVING-COIL-METER-1MA-/130753131630?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item1e717e746e
abechap024
Well-known member
Edward said:
What do you mean exactly? You don't need to add anything. The only connection you will need to "ground" (connecting the audio ground to chassis ground) will be at one of the input XLRs (you have all the pin 1s of all your xlrs connected directly to chassis at the xr right? ) and you only connect any of the XLR pin 1s at ONE and only one xlr to the respective pin 1 on the pcb.
Hope that helps
Abe
Edward
Well-known member
abechap024 said:Edward said:
What do you mean exactly? You don't need to add anything. The only connection you will need to "ground" (connecting the audio ground to chassis ground) will be at one of the input XLRs (you have all the pin 1s of all your xlrs connected directly to chassis at the xr right? ) and you only connect any of the XLR pin 1s at ONE and only one xlr to the respective pin 1 on the pcb.
Hope that helps
Abe
I was reading the rev 1 thread and somebody was writing about that... From now on I will try to stick to the plan and stop trying to figure out stuff by my own as it usually turns out horribly wrong. Thanks again.
abechap024
Well-known member
Edward said:abechap024 said:Edward said:
What do you mean exactly? You don't need to add anything. The only connection you will need to "ground" (connecting the audio ground to chassis ground) will be at one of the input XLRs (you have all the pin 1s of all your xlrs connected directly to chassis at the xr right? ) and you only connect any of the XLR pin 1s at ONE and only one xlr to the respective pin 1 on the pcb.
Hope that helps
Abe
I was reading the rev 1 thread and somebody was writing about that... From now on I will try to stick to the plan and stop trying to figure out stuff by my own as it usually turns out horribly wrong. Thanks again.
Hi Edward,
Sorry I know its pretty confusing!
abechap024
Well-known member
earl said:
Thanks for the kind words
Much thanks goes to PRR though, hes the mastermind behind the original idea. I must agree, these units do sound nice!
Hi!
I'm having a problem with my power transformer(s) 230v
I have 2x25vac and 2x15vac toroids.
I've connected one 24vac secondary to 15vac secondaries witch are connected in series and I get 260vac am I doing something completely wrong here?
Thanks!
I'm having a problem with my power transformer(s) 230v
I have 2x25vac and 2x15vac toroids.
I've connected one 24vac secondary to 15vac secondaries witch are connected in series and I get 260vac am I doing something completely wrong here?
Thanks!
abechap024
Well-known member
sedit1 said:
Do you have the 15V transformer the one that is connected to the mains? Also maybe measure each transformer to be sure of the voltage they are putting out.
abechap024 said:
Thanks Abe,
The 2x24v is connected to mains. Transformers measure 2x24->28vac 2x15->18vac. I've connected them like in the g9 picture http://i73.photobucket.com/albums/i222/skylargray/G9/G9Toroidconnections.jpg
I think that might be the problem? Because I was just testing this with tx's what I have at home already but they are just single primary straight to 230v. So I think I need the 15vac to be dual primary and also connect the "new secondary" in series?
abechap024
Well-known member
Well if you have the 24V connected to mains, and then connect that to the 15V transformer your going to get more that 230V on the output. Which for the G9 is fine, but this project you only want 120V or so.
When you apply 15V to the secondary side of the 15V transformer you will get the spec'ed 230V on the primaries. What happens when you increase the voltage on the secondaries? The voltage will raise faster on the primaries. So if you apply 24Vs to the 15v transformer its no big surprise you are getting more than 230v right?
(I know the whole "secondary" and "primary" is a little confusing because we are flipping the transformer around and essentially using the primary and the secondary etc etc, don't get confused its all the same to the power transformer!)
So then applying the same logic to the 24V transformer. When you apply roughly 24V on the secondarys of the transformer you get roughly 230V on the output, right? Since we want a little more than half that voltage, we'll apply a little more than half that on the secondaries. Wait, you still have that 15V transformer right? That will be perfect.
Make sense?
230::15::24::150ish
BE SAFE!
When you apply 15V to the secondary side of the 15V transformer you will get the spec'ed 230V on the primaries. What happens when you increase the voltage on the secondaries? The voltage will raise faster on the primaries. So if you apply 24Vs to the 15v transformer its no big surprise you are getting more than 230v right?
(I know the whole "secondary" and "primary" is a little confusing because we are flipping the transformer around and essentially using the primary and the secondary etc etc, don't get confused its all the same to the power transformer!)
So then applying the same logic to the 24V transformer. When you apply roughly 24V on the secondarys of the transformer you get roughly 230V on the output, right? Since we want a little more than half that voltage, we'll apply a little more than half that on the secondaries. Wait, you still have that 15V transformer right? That will be perfect.
Make sense?
230::15::24::150ish
BE SAFE!
abechap024 said:
Thanks Abe this makes perfect sense!
This was just testing the technique. My main Idea was that I would order 1x18v and 1x12v dual primary toroids -> 230::18vac::12vac secondaries in series::172.5vac (new secondary in series)
Then I would still have the other 18v winding for my 18vac input.
Does this make any sence or would it be just easiest to buy 230->115vac toroid and also use 2x18vac for 18v?
Thanks!
abechap024
Well-known member
sedit1 said:
You could use both ways. Though getting a separate (or a transformer with the correct taps) for 115V would be best.
ethervalve
Well-known member
Hi all,
Just got mine together and turned it on, psu voltages are ok but I need to do a bit of troubleshooting.
I'm a little confused by one thing in the schematic (incidentally, is the Rev1 schematic still OK to follow for Rev2 boards?):
when using the IC input option (which I'm doing), do I just jumper the OPT_1 and OPT_2 pads? Or do any of the transformer pads require bridging?
Thanks in advance
Just got mine together and turned it on, psu voltages are ok but I need to do a bit of troubleshooting.
I'm a little confused by one thing in the schematic (incidentally, is the Rev1 schematic still OK to follow for Rev2 boards?):
when using the IC input option (which I'm doing), do I just jumper the OPT_1 and OPT_2 pads? Or do any of the transformer pads require bridging?
Thanks in advance
abechap024
Well-known member
ethervalve said:
You still need the interstage transformer, or the 2 interstage transformers per channel. 4 total for the board. then you bridge both "in-ops" if your using the chip input as apposed to a t-pad attenuator. And yes rev 1 schematic is still good.
ethervalve
Well-known member
ha, I'm a buffoon. Thanks Abe. The one channel I have enough transformers for sounds great! (Seems to make cymbals sound a little nicer than are in reality; also really get's that 'September Gurls' comp'd guitar sound nicely).
edit:
I love this thing enough that I'm mulling the idea of building a second one next year. Have any of the earlier builders noticed if the threshold calibration remains stable over time? I ask this because I'm thinking it would be cool to have a 2 or 3-way switch with different calibrated threshold settings. In my case I'd be using it 75% of the time as a console insert (nominal -10dBu) and the remaining quarter of the time connected to +4dBu 2-track outs.
Also, have any of you who used the hairball/nissei meters tried replacing the scale? I'm OK with it as is, but it would be interesting to know if scale modding worked out for anyone.
edit:
I love this thing enough that I'm mulling the idea of building a second one next year. Have any of the earlier builders noticed if the threshold calibration remains stable over time? I ask this because I'm thinking it would be cool to have a 2 or 3-way switch with different calibrated threshold settings. In my case I'd be using it 75% of the time as a console insert (nominal -10dBu) and the remaining quarter of the time connected to +4dBu 2-track outs.
Also, have any of you who used the hairball/nissei meters tried replacing the scale? I'm OK with it as is, but it would be interesting to know if scale modding worked out for anyone.
