Nelson Pass B-1 preamp kit

wushuliu · « **Reply #40 on:** 7 Mar 2010, 01:18 am »

Well got part of the build done and plenty of pics. Still waiting for a bunch of stuff from Digikey. I'll get the first set of pics and commentary up soon!

shadowlight · « **Reply #41 on:** 7 Mar 2010, 01:21 am »

Anyone planning to put a remote control and ht bypass? Any pointers on where you can pickup a remote control?

wushuliu · « **Reply #42 on:** 7 Mar 2010, 01:39 am »

Quote from: shadowlight on 7 Mar 2010, 01:21 am

Anyone planning to put a remote control and ht bypass? Any pointers on where you can pickup a remote control?

A remote control setup would certainly complicate things, but if you are so inclined. You
could try:

http://www.partsconnexion.com/product13983.html

http://diyclub.biz/catalog/product_info.php?products_id=247

shadowlight · « **Reply #43 on:** 7 Mar 2010, 01:42 am »

Quote from: wushuliu on 7 Mar 2010, 01:39 am

A remote control setup would certainly complicate things, but if you are so inclined. You
could try:

http://www.partsconnexion.com/product13983.html

http://diyclub.biz/catalog/product_info.php?products_id=247

Thanks for the links. I will try the non-remote version first and gradually make my way up

earplay · « **Reply #44 on:** 7 Mar 2010, 03:54 am »

Just for everyone's information. I ordered one of those Chinese diy kits from eBay to make a Pass pre. It's going on three weeks and no kit yet. Parts from Canada arrived before the Hong Kong kit.

Also, what's an "ht bypass"?

The LSA installed into the Pass pre would be VI (Very Interesting). See there, I can do initials. A how-to follow-up on the LSA/Pass pre would be appreciated. I've got time on my hands, so....

shadowlight · « **Reply #45 on:** 7 Mar 2010, 04:19 am »

Quote from: earplay on 7 Mar 2010, 03:54 am

Also, what's an "ht bypass"?

My system is dual purpose system. It is both 2-channel and home theater. HT Bypass basically allows me to by pass the pre from my receiver directly into the amp.

earplay · « **Reply #46 on:** 7 Mar 2010, 04:22 am »

Aaahhhh... ht = home theater. DUH

Thanks!

wushuliu · « **Reply #47 on:** 7 Mar 2010, 05:05 am »

Quote from: earplay on 7 Mar 2010, 03:54 am

Just for everyone's information. I ordered one of those Chinese diy kits from eBay to make a Pass pre. It's going on three weeks and no kit yet. Parts from Canada arrived before the Hong Kong kit.

Also, what's an "ht bypass"?

The LSA installed into the Pass pre would be VI (Very Interesting). See there, I can do initials. A how-to follow-up on the LSA/Pass pre would be appreciated. I've got time on my hands, so....

Looks like you ordered during the chinese holiday, hence the delay.

walkern · « **Reply #48 on:** 7 Mar 2010, 01:36 pm »

I ordered one of the Chinese kits about 2 weeks ago, and it arrived day before yesterday. The packaging was rather limited... a bubble enevelope with the board stuffed insided (wrapped in very thin bubble wrap) and a bag o' parts... but everything appears to have survived the journey. Now I'm waiting for assembly details from those kind and generous sorts who've been successful at this already. Note that there is no switch for selecting inputs with the kit, and the volume pot looks pretty so-so, although at least it appears that one could mount/solder it directly to the board.

Neil

earplay · « **Reply #49 on:** 7 Mar 2010, 02:53 pm »

Thanks guys!

I've got Alps pot around here somewhere that I intend to use until the LSA situation is worked out.

Walkern, you imply that there are no instructions with the kit. Rats! I have the schematic they emailed to me, but I cannot read a schematic. I can read instructions and diagrams so we are in the same boat, waiting for others to provide a paddle.

HAL · « **Reply #50 on:** 7 Mar 2010, 04:12 pm »

Here is my Pass B1 board with parts installed before soldering. Two different views.

The B1 Board has silk screened parts numbers on it for stuffing.

Edit: The Alps Blue Pot, 100Kohm version for input volume control.

sondale · « **Reply #51 on:** 7 Mar 2010, 04:59 pm »

Hi,

I have also built up the board with loads of photos - hopefully I can get them loaded on Monday - I have to reduce them in size before posting.

Alan

schubert · « **Reply #52 on:** 7 Mar 2010, 05:16 pm »

Here's my Pass B-1 for anyone who is interested.

It's powered by a TREAD and uses PEC carbon pots, which sound nice but introduce some operational awkwardness.

wushuliu · « **Reply #53 on:** 7 Mar 2010, 06:00 pm »

Ok kids, here we go. I hope the pics are good enough, but I will also provide a link to the full rez pictures so you can zoom in if you need to.

Now I will assume that the builder will have soldered at some point in their life. If, however you need a refresher or will be taking the leap for the first time, then I highly recommend the first 2 tutorials on the following page:

http://tangentsoft.net/elec/movies/

Below is Nelson's PCB.

As you can see it is nice and spacious and very well laid out, no parts will be interfering other parts. The Part numbers are on the board as you can see, but you will need to refer the pdf to see what values correspond to what number.

http://www.passdiy.com/pdf/B1%20Buffer%20Preamp.pdf

I printed out the sheet and placed it behind the board for easy reference.

R= resistor, C=Capacitor, Q = JFET, D= diode, led

As a general rule of thumb, it is best to start populating a pcb with smallest/shortest height components first.

So that means the resistors. So just pop one in and start solderin'!

Alright. Almost done!

Ok, not quite. But the resistors make up a bulk of the soldering, take a break and rub hands together in wicked glee.

wushuliu · « **Reply #54 on:** 7 Mar 2010, 06:04 pm »

Next up are the four matched JFETS that come with Nelson's board.

Be sure it is oriented the right way when soldering. As you can see from the outline on the board, the 3-pronged jfet has a flat back and curved front - so be sure to put them in the right way.

Another good reason to buy Nelson's directly is it can be difficult to source the JFETs and since his are matched you can be assured you're getting the best out of them. Or whatever. I don't really know what they do.

let's melt some lead!

Gettin' closer!

wushuliu · « **Reply #55 on:** 7 Mar 2010, 06:04 pm »

Now we come to the input and output capacitors.

This where you have some room to experiment and show off your audiophile cred/bling. Nelson designed his with regular Axon polypropylene caps similar to the Dayton's I have below. Good enough for him, then that'll be good enough for you, but if you want to season your B1 to get that certain flavor you may find a big payoff to swapping caps (let's leave the arguments in another thread, this is strictly a suggestion, nothing more).

The one thing the Chinese ebay pcb has which Nelson's does not is a set of different lead spacings to accomadate different sized capacitors. With the Dayton's I had to bend the leads in a little on one side
to get them in on Nelson's board. No big deal, just be sure you don't block any upcoming parts.

Lookin' good!

Bemopti123 · « **Reply #56 on:** 7 Mar 2010, 06:07 pm »

wushuliu · « **Reply #57 on:** 7 Mar 2010, 06:15 pm »

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 · « **Reply #58 on:** 7 Mar 2010, 06:15 pm »

Up next is the 3W 1 0hm resistor.

And now the generic diode...

Note that the diode has a stripe on one side.

Be sure that the striped side of your diode matches the stripe on the pcb.

Sorry, had a hard time getting a clear shot, but you get the, uh, picture

Now the 1uf PS bypass cap.

wushuliu · « **Reply #59 on:** 7 Mar 2010, 06:15 pm »

Next up, PEC volume pots.

Btw: CW=input W=output CCW=ground

Inputs first

And there we be.

If your are using a stereo Alps pot, the wiring is as below: