All things Green Pre

[Phrazemaster]

Thank-you Peter. You have endless patience! I appreciate it.

 

[Phrazemaster]

Although I've spent an inordinate amount of time on everything, I am making slow progress. I just wanted to post a picture of my current vision of the completed product; all things subject to change!!

Thanks any thoughts,

Mike

 

[Phrazemaster]

OK, a question. Granted relays aren't generally rated as high as 48v, but I see quite a few that will say up to 30VDC@2A, for example.

My reading tells me phantom power specs max out at 10mA...so how could I calculate if a switch could handle low amps at a higher voltage? It wouldn't just be ohms law, would it? Is there a way to tell if a switch/relay can handle higher voltage but much lower amperage? Or is it just a gamble ending with smoking components if I'm wrong?

Just feeling my way through all of this. Thanks gang.

Mike

 

[Phrazemaster]

Well with the new switches I'm getting and some more thought, here's another re-imagining of the final product... comments welcome.

 

[watkinth]

Hello all,

I'm a bit of a newbie at this, and have been combing the forums for months now on all of the information that I would need to build a pair of Green pres.  I already got the boards needed from Peter, and I've been reading the BOM and doing all sorts of electronics research into how everything is supposed to work, and I think I have the right parts ready to order.  Is there anyone who could take a look at my order and just double check to make sure I'm not going to order the massively wrong parts?  I'm ordering a few extra of most of the parts just because I don't exactly have any spares on hand for anything, but it should all be there except for the transformer, switches, and jacks.  The transformer I am getting is the Avel Lindberg from Parts Express, part num. Y236103 (it's been mentioned in the various power threads in the meta).

I also can't find a 3A, 100V bridge rectifier for the power supply ANYWHERE!  They're backordered until January at Mouser, and pretty much everywhere else doesn't stock them in the first place.  If anyone hears of a place that has them sooner please let me know!

Thanks for any help, and I welcome any suggestions on where I should go to get more general electronics information or any other build advice!

Taylor

 

[watkinth]

Of course after all of that I failed to post the Mouser project number, so here it is: ba4135afac.  Thanks!

Taylor

 

[Phrazemaster]

HI Taylor, welcome to the group!

I just searched Mouser, Digikey, Farnell, Octopart, Newark...I didn't find one either. However, there is probably a suitable alternative; perhaps a more knowledgeable member can suggest?

Good luck, and do post your progress and thoughts.

I'm in the middle of building a quad pre myself, so we'll have lots to share!

Mike

 

[peterc]

Mike

Front panel looks good.

Taylor

You can use  anything rated higher than that, so a 4A 200v rectifier should be good. My standard part is is a 4A 400v part.

Peter

 

[Phrazemaster]

Thanks Peter!

 

[isophase]

i can't find any Green pre PCB ?
who makes them ?

 

[peterc]

Me!

Send me a PM

Regards
Peter

 

[watkinth]

Thanks a lot!  4A 400V looks like a winner.  Time to get started on the build!

Taylor

 

[Phrazemaster]

Hi, I have a question probably for Peter, but if anyone else knows, great!

I am going to use illuminated switches, DPDT. One pole to drive the LEDs/incandescent bulbs, the other to operate a standard DPDT relay for HPF and phase.

My question is, can the power supply handle this extra load without problem? These are standard non-latching relays, so when the switches are engaged, they will be on continuously drawing power. Some wiser than I told me in another post that there is no need to use latching relays/ic's to drive all this, since this is not battery powered.

So, is this doable, or should I look at a latching dual coil design to minimize current draw? And if a standard relay is fine, then any suggestions on voltage? I can go as low as 1.5v, but I'm assuming a 5v would work fine here...

I don't want to reduce the pre's power or affect the audio, so if this is not smart, let me know.

Thanks in advance!

Mike

 

[Phrazemaster]

PS I should mention, I have the concern about the power because I am making a 4-channel green and will have 12 LEDs/incandescent bulbs (of which I have no idea what voltage to choose), and 8 standard relays drawing current if all those buttons are engaged...just got me worried about if the psu can handle all that easily without compromising the audio.

thx

mike

 

[Phrazemaster]

OK, back for another installment. I'm making another board to interface with the green, to add relays/leds. I have a question. Do interconnects cause problems internally? I want the layout inside to be neat, and not have wires from the main board going up to the panel over the secondary board; it gets ugly and messy fast.

However, the tradeoff is I need to connect the boards together, and I want to use some molex type connectors. Would there be an ill effect the sound if I use some molex connectors internally, instead of soldering directly? I know the solder connection is best, but I want this to be a more modular, neater design.

Here is a quick rough layout of the board for one channel. Forgive the mess; I keep rearranging everything and before going further I wanted some thoughts. It's a double sided board; the red is the top and the green is the bottom layer. I know I know, it looks like christmas!

Is there a problem just running the led bank up from the bottom to the top of the board, and the same with the trim pot; I know in a perfect world it's fine but practically speaking am I going to cause harm to the quality of the sound?

And is putting the phantom pwr a bad idea on this board? There will be 4 channels, so this will be repeated 4x.

Also, I added a couple of buffering caps (I figure .1uf) on the phantom pwr and also on the power to the little board; any thoughts on that?

Thanks so much!

Mike

I also a

Thanks,

Mike

 

[Phrazemaster]

Final Version (I think...)

hey, I don't know if anyone's following or not anymore on this thread, but after many hours I've come up with this as a design for my LED/Routing board. Basically it takes the HPF and Phase sections and allows using a relay with SPST illuminated switch. The relay uses standard dip spacing so what you see is a 14-pin IC socket, 4 positions to remain unused. This way if the relay ever fails I can just change it out easy. The Phantom power I am using a DPDT illuminated, which is why there's no relay for it. I also routed all the outputs from the end of Peter's board to make it a cinch to wire up.

Now, I *was* going to set it up all modular and cool-like, with connectors for every in/out. After many exhausting hours, I've discovered something probably many of you know...connectors are EXPENSIVE! Damned expensive. Especially in various sizes, etc. So after spec'ing it out 50 ways to sunday using interconnects, I threw in the towel on those. I can save a whole lotta cash just soldering in directly, not to mention the dubious nature of using molex connectors for our precious sound signals...so, talley ho! I'll keep posting, and hopefully someone will gimme a shout that they are still interested/following.

 

[PAGEN]

Hi
Just a newbi with a question. How do you perform this test without a scope? Things marked red. The rest is ok.

1. Find 2 100R resistors that are as matched closely as possible, ideally to 0.1 ohm.
2. Solder one end of each of the resistors together to form a 'V'.
3. Solder the un-attached legs of the resistors to the + & - inputs of the preamp.
4. Set the gain switch to the middle of it's rotation.
5. Set your signal generator to 100Hz and attach the positive lead to the joint of the 2 100R resistors. Other lead to GND. Amplitude 1v pk-pk.
6. On your scope, monitor the output of pin 1 of the middle 5532.
7. Trim the 1K trimmer until the signal on the scope is as low as possible. It should be possible to get it down to 1 or 2    mV.

This is my second build and I'm starting to get a hang of it. My first was a GSSL.

All mesuraments so far is fine and I hope to be build one more soon.

I have a ton of questions but I will start with this.

Here are a pic of the build so far.


Thanx

Mats

 

[Phrazemaster]

Just wanted to update my build process so far. Have all parts. Have designed/had made an LED driver board, the one you've seen the "christmas" colors of in previous posts. Pic of final product posted in this post. Will add more pix in next post.

 

[Phrazemaster]

Here's a final rendering of the front panel, which is being made by front panel express.

 

[Phrazemaster]

Finally, here is a pic of the knobs, which I bought from digikey and am customizing to match the "artist rendering" you saw in the above post. What a @@# load of work sanding!!!

The upper right knob is an untouched knob; the others are in varying degrees of processing. I wish I knew how to post more than one pic per post.