Nelson Pass B-1 preamp kit

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parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #220 on: 22 Apr 2010, 01:49 am »
alas, I roll my own interconnects, so I don't really have a recommendation for anything retail.

How did you do that?  Could I use regular wires and put them in plugs?  I bought quite some 20 awg apex jr wires and that would be a fantastic idea if I can use these to make interconnects.  Where to source RCA plugs?

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #221 on: 22 Apr 2010, 07:05 pm »
Question about the input switch.  How do we know which lug is right and which lug is left output? Which side is source 1 and which one is source 2?  Or it doesn't matter as long as I am consistent with L and R - like all Ls on one row and all Rs on one row?

Btw, for the Alps Pot, is the G O I the same layout as PEC pot?  like from left to right, G -> O -> I when the shafe facing me.

Thx!

Now we'll take on the input switch.



We have a DPDT for 2 source inputs. It has 6 solder lugs as you can see. The center two are the L/R outputs. The outer two are Source 1 L/R and Source 2 L/R. Hopefully the pics convey what goes where easily.

Source 1 Right



Source 1 Left




Now into the appropriate holes



As you can guess, the center two will go the middle, and the Source 2 L/R will be soldered to the bottom two on the board.




That's it for today. The Digikey stuff comes in tomorrow (I used spare resistors for this build), and I'll continue then.

wushuliu

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Re: Nelson Pass B-1 preamp kit
« Reply #222 on: 22 Apr 2010, 08:26 pm »
Or it doesn't matter as long as I am consistent with L and R - like all Ls on one row and all Rs on one row?
Thx!

correct

Btw, for the Alps Pot, is the G O I the same layout as PEC pot?  like from left to right, G -> O -> I when the shafe facing me.

Thx!




parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #223 on: 22 Apr 2010, 09:18 pm »

wushuliu

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Re: Nelson Pass B-1 preamp kit
« Reply #224 on: 22 Apr 2010, 11:33 pm »
I have one question:

- what would be the single, most influential (sound characteristic wise) part in this circuit ?

whoa, sorry Mariusz I totally missed your post. I would say the input/output caps, followed by the 1k output resistors. A good test for flavoring would be the 2 1uf input caps. I was tempted to ask you what kind of tonality you prefer, lean/neutral or warm/neutral and then swap in (hopefully) appropriate caps/resistors but I figured I would KISS and just go straight no chaser.

My guess is your B1 would be sounding on the lean, clinical side? Maybe a little forward with the dale resistors. I have found Claritycaps to smooth things out, add warmth and some space.

Mariusz

Re: Nelson Pass B-1 preamp kit
« Reply #225 on: 22 Apr 2010, 11:51 pm »
Got ya. 
Planing to roll some caps just for fun and personal curiosity.
Thanks again Wusu.

Cheers
Mariusz  :wink:

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #226 on: 23 Apr 2010, 04:36 am »
"Hum..."  Ground Noise?

So I hook it up tonight.  It works!  However, the right channel has big "hum" sound.  I put the board open.  No boxes, laying on the carpet.  Interesting enough, when I touched the power caps - the hum lowered or disappeared.  When I lift the board, the hum sound would decrease.  When my hand touching the back of the board, resistors and JEFTs, left channel will have hum sound and noise will increase. 

Not sure what to do.  Any advises are appreciated!

wushuliu

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Re: Nelson Pass B-1 preamp kit
« Reply #227 on: 23 Apr 2010, 04:42 am »
How did you do that?  Could I use regular wires and put them in plugs?  I bought quite some 20 awg apex jr wires and that would be a fantastic idea if I can use these to make interconnects.  Where to source RCA plugs?

If the apex jr wire is stranded, then sure why not. But don't you have a couple different projects on your plate right now?  :lol:

wushuliu

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Re: Nelson Pass B-1 preamp kit
« Reply #228 on: 23 Apr 2010, 04:45 am »
"Hum..."  Ground Noise?

So I hook it up tonight.  It works!  However, the right channel has big "hum" sound.  I put the board open.  No boxes, laying on the carpet.  Interesting enough, when I touched the power caps - the hum lowered or disappeared.  When I lift the board, the hum sound would decrease.  When my hand touching the back of the board, resistors and JEFTs, left channel will have hum sound and noise will increase. 

Not sure what to do.  Any advises are appreciated!

? just laying on the carpet? How about getting it on a proper surface of some kind instead of static-y carpet and pics are always a big big plus...

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #229 on: 23 Apr 2010, 12:49 pm »
? just laying on the carpet? How about getting it on a proper surface of some kind instead of static-y carpet and pics are always a big big plus...

Carpet is static-y oh- So that's the same reason with my hands I guess.  I put them on a MDF and had similar results but that could be twisted when I move the board around.  I'll check all the joints again and post pictures.  I think I have very bad soldering skill too.

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #230 on: 23 Apr 2010, 02:10 pm »
So I rechecked all solder joints and fixed some - the situation is the same.  I put the board on a MDF and lift it so no direct contacts with the board from the bottom (picture below) - no changes.

The situation is now like this:  When I hook it up (Class D amp), I turn the volume to minimum, input switch to the correct input (either 1 or 2), and there will be "Buzz or Hums" from the right channel.  When I turn the volume to maximum, "Buzz and Hums" will come out from both channels.  If I touch the bottom of the left most resistor, there will be big hum/buzz from the left channel (regardless of whether there is input signal or not).

When music is coming from Input 1 and I set the input switch to "Middle" or "input 2", if I turn the volume all the way to maximum, I can hear the music playing in low volume along with big hum/buzz.  I feel like the sound is "leaking".  Is that normal?

I added the LED and it is working correctly - it will light up when the power is on.







wushuliu

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Re: Nelson Pass B-1 preamp kit
« Reply #231 on: 23 Apr 2010, 04:39 pm »
So I rechecked all solder joints and fixed some - the situation is the same.  I put the board on a MDF and lift it so no direct contacts with the board from the bottom (picture below) - no changes.

The situation is now like this:  When I hook it up (Class D amp), I turn the volume to minimum, input switch to the correct input (either 1 or 2), and there will be "Buzz or Hums" from the right channel.  When I turn the volume to maximum, "Buzz and Hums" will come out from both channels.  If I touch the bottom of the left most resistor, there will be big hum/buzz from the left channel (regardless of whether there is input signal or not).

When music is coming from Input 1 and I set the input switch to "Middle" or "input 2", if I turn the volume all the way to maximum, I can hear the music playing in low volume along with big hum/buzz.  I feel like the sound is "leaking".  Is that normal?


The middle position for the switch should be 'off' so there should be no noise/sound at all. My guess is the switch/pot wiring is off. Could you take a closer pic or draw a diagram of how you wired the switch and alps?

earplay

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Re: Nelson Pass B-1 preamp kit
« Reply #232 on: 23 Apr 2010, 10:36 pm »
My half-pence... I am glad and grateful this thread continues to add technical info. I will be building a PassDIY B1 soon, having slaughtered a Chinese board. My bad. No pictures will be forthcoming.   :oops:

Sondale helped me a lot and now I'm on track, I think, to a great pre. It's that kind of assistance that creates a good feeling for this hobby.  :thumb:

Tried to order the Pass board today, but found that the DIY site was down. Seems it was hacked to install malware on visitors' PC's. You might want to check your machine.

 

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #233 on: 24 Apr 2010, 06:14 pm »
Well, the verdict is in.  It's the ground issue.  I put the PCB in inside an old DVD player (metal enclosure) and did a chassis ground from four corners of the PCB.  The noise disappeared.  So my plan of using a MDF box is gone.  Need to find a alumninum enclosure.  This design will attract lots of noise without enclosure / shielding / grounding.  To be safe, metal enclosure is the way to go.  So what would be an economical alumninum enclosure? :)

The middle position for the switch should be 'off' so there should be no noise/sound at all. My guess is the switch/pot wiring is off. Could you take a closer pic or draw a diagram of how you wired the switch and alps?

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #234 on: 25 Apr 2010, 12:43 am »
RCA Jacks.

I bought RCA jacks from Parts Express.  I found out that my jacks are not shielded from the chassis. 

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=090-278

However, since the touching part of the RCA jacks to the chassis are grounds, it should be better that way.  Right?

Thx!

avionic

Re: Nelson Pass B-1 preamp kit
« Reply #235 on: 25 Apr 2010, 03:55 am »




  Finally got my b1 up and running in a temporary enclosure. I can't believe how good this sounds. I am using cheap pots from radio shack until the stepped dact type attenuator gets here. Even so the sound is fantastic and dead silent. Many thanks to Wushuliu for starting this thread and all the work including the parts list. Also thanks to Mr. Pass for bringing this to the DIY community. I can't wait to get the attenuator and permanent enclosure and finish this up. Just a heads up for those that are going to use only one source. The inputs can be jumpered as I did so you don't have to buy a switch and wire it up.
   Thanks again everyone  :thumb:

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #236 on: 25 Apr 2010, 03:57 am »
What enclosure would you use?




  Finally got my b1 up and running in a temporary enclosure. I can't believe how good this sounds. I am using cheap pots from radio shack until the stepped dact type attenuator gets here. Even so the sound is fantastic and dead silent. Many thanks to Wushuliu for starting this thread and all the work including the parts list. Also thanks to Mr. Pass for bringing this to the DIY community. I can't wait to get the attenuator and permanent enclosure and finish this up. Just a heads up for those that are going to use only one source. The inputs can be jumpered as I did so you don't have to buy a switch and wire it up.
   Thanks again everyone  :thumb:

avionic

Re: Nelson Pass B-1 preamp kit
« Reply #237 on: 25 Apr 2010, 04:03 am »
 Still looking for the enclosure Parodielin. I may end up making one myself. There is a place online that sells aluminum sheet up to an inch thick and they will cut to size.

parodielin

Re: Nelson Pass B-1 preamp kit
« Reply #238 on: 25 Apr 2010, 04:05 am »
Still looking for the enclosure Parodielin. I may end up making one myself. There is a place online that sells aluminum sheet up to an inch thick and they will cut to size.

Where is it?  How much will they charge?  I am eyeing on a Hammond chassis + bottom (1441-24BK3) around $45 shipped. 

avionic

Re: Nelson Pass B-1 preamp kit
« Reply #239 on: 25 Apr 2010, 04:08 am »
  Let me see if I can find the place and then post a link. I have a hard time finding it on my home computer but it pops right up at work. Different search engine I guess.
    Found it      http://www.onlinemetalstore.com/