Nelson Pass B-1 preamp kit

earplay · « **Reply #160 on:** 1 Apr 2010, 07:26 pm »

Thanks ebag4,

But I did exactly as your diagram suggests. I was hoping to get this done tonight. sondale has probably gone to bed, by now because he lives in the UK.

I'm not well-informed about electronics, but I don't think I'm giving myself too much credit when I believe that even I can figure out a one-to-one correspondence. It's disheartening!

The thing that has me going is that both channels will play, just not simultaneously. I conclude then, that both channels of the board are assembled correctly. The problem must be with the switch.

sondale and you suggested I swap a couple of leads. I swapped S100a with S200a, but that caused the sound to come out of only the right channel when the switch was in either position.

I've concluded I need professional help. I don't mean electronic help, either!

EDIT: Alan, just got your message. Which is the bottom in your view? I'll rewire according to your plan. The behaviour does suggest that mere swapping straight across will not solve the problem, IMHO.

EDIT 2: Alan, just got your diagram. Will report back.

wushuliu · « **Reply #161 on:** 1 Apr 2010, 07:34 pm »

I believe its

R2 L1
OUTR OUTL
R1 L2

ebag4 · « **Reply #162 on:** 1 Apr 2010, 07:36 pm »

Quote from: sondale on 1 Apr 2010, 07:25 pm

I think it is the board - if you look at the left/right inputs for 1 the left goes to the bottom pin on S100 and the right goes to the top pin of S200!

Alan

I agree with Sondale. Looking at the switch connections on your board it appears that the S100 side uses the bottom (as the pic is oriented) to switch input 2 and S200 uses the top top to switch input 2. If you take one side and move the top wire to the bottom and bottom to top you might fix your problem. A meter to check continuity from the input to the switch connection would be very beneficial.

edit: Just like Wishuliu is showing in his post above.

Best,
Ed

earplay · « **Reply #163 on:** 1 Apr 2010, 07:52 pm »

Healed!!!

Indeed, as sondale suggested, the board is laid out incorrectly. When I swapped the switch's leads so they were not in one-to-one correspondence, everything worked as advertised.

How can I thank you. sondale, you da' man!

And everyone else who helped, thanks to you, too.

sondale · « **Reply #164 on:** 1 Apr 2010, 07:54 pm »

Quote from: earplay on 1 Apr 2010, 07:52 pm

Healed!!!

Indeed, as sondale suggested, the board is laid out incorrectly. When I swapped the switch's leads so they were not in one-to-one correspondence, everything worked as advertised.

How can I thank you. sondale, you da' man!

And everyone else who helped, thanks to you, too.

As we say over here - Bloody Good Show - now sit back and enjoy!

wushuliu · « **Reply #165 on:** 1 Apr 2010, 09:37 pm »

Quote from: earplay on 1 Apr 2010, 07:52 pm

Healed!!!

Indeed, as sondale suggested, the board is laid out incorrectly. When I swapped the switch's leads so they were not in one-to-one correspondence, everything worked as advertised.

How can I thank you. sondale, you da' man!

And everyone else who helped, thanks to you, too.

Sweet...

earplay · « **Reply #166 on:** 2 Apr 2010, 12:29 am »

Being unable to endure what can be changed, especially if it can be changed cheaply, I removed the blue input and output connectors and soldered the wires directly to the board. Then I bypassed the 10uf caps with VISHAY-RODERSTEIN MKP-1837 Caps I had lying around. Well, those changes helped things in terms of clarity and detail. Not that the stock Chinese B1 did not improve the clarity and detail of my system. I must say though, that the B1 is smooth, too. Very smooth!

Also, I'll probably install the Alps Blue I have setting around. That may help matters. The tonality of this thing is great already, though.

Thanks again to everyone. Now I'll try to piece together an American-sourced B1.

wushuliu · « **Reply #167 on:** 2 Apr 2010, 12:46 am »

Quote from: earplay on 2 Apr 2010, 12:29 am

Being unable to endure what can be changed, especially if it can be changed cheaply, I removed the blue input and output connectors and soldered the wires directly to the board. Then I bypassed the 10uf caps with VISHAY-RODERSTEIN MKP-1837 Caps I had lying around. Well, those changes helped things in terms of clarity and detail. Not that the stock Chinese B1 did not improve the clarity and detail of my system. I must say though, that the B1 is smooth, too. Very smooth!

Also, I'll probably install the Alps Blue I have setting around. That may help matters. The tonality of this thing is great already, though.

Thanks again to everyone. Now I'll try to piece together an American-sourced B1.

If you're going to put another one together, go for some better quality caps and resistors if you can. The (2)1uf Input caps at least. The B1 is simple enough that any of those changes are reflected in the sound in a big way. So there's no where to go but up...

Angela's Instruments sells Takman, Riken, etc. resistors for cheap and they ship first class so you wont get hit w/ shipping costs. The (4) 1k resistors are the ones you will want to upgrade. Or even just 2 of them, to prevent 'too much of a good thing'. The rest you can go digikey per the BOM (including TS-HA for the PS caps!).

http://angela.com/rikenohmresistors.aspx

earplay · « **Reply #168 on:** 2 Apr 2010, 01:31 am »

Whoops! What's this?

The right channel fades out after about a minute of play. If I turn the B1 off for a few seconds, then repower it, both channels sound fine until the right channel fades out. I've done this five times now. Any ideas?

sondale · « **Reply #169 on:** 2 Apr 2010, 10:45 am »

Quote from: earplay on 2 Apr 2010, 01:31 am

Whoops! What's this?

The right channel fades out after about a minute of play. If I turn the B1 off for a few seconds, then repower it, both channels sound fine until the right channel fades out. I've done this five times now. Any ideas?

Oh dear!

Did it do this before you changed the inputs and added the bypass caps?

I would think there are two things could be wrong, firstly a cap is misbehaving - normally this would be an electrolytic - but if that was the case then it would be both channels fading. The other is that the jfets were damaged by the reverse voltage.

Recheck the solder joints on your latest work.

earplay · « **Reply #170 on:** 2 Apr 2010, 01:47 pm »

I must admit that I didn't attend closely enough to know when this happened. As I said, it takes about a minute. In that time, I would listen for a short period, then shift my attention to something else and let the B1 break-in. So, I don't know which change caused the problem.

The B1 has two electrolytics, so I was thinking one per channel. In that case, I thought, an electrolytic could go bad and not affect the other channel. But, I know I could be wrong in my assumptions there.

I do suspect my soldering of the volume pot because I can't see the rear connections very well. The legs did not align precisely with the holes, so I had to bend the legs somewhat. The rear legs do not protrude through the holes, so I may have a problem there.

I'll remove the pot and try to rejoin it to the board. Also, my afternoon is committed elsewhere, so I may not be able to fix this until tomorrow, when I have good light. I'll wire the pot to the board instead of soldering it directly. Then I can be sure my joints are good.

Will report back. Thanks again! Have a sunny day.

sondale · « **Reply #171 on:** 2 Apr 2010, 02:21 pm »

Quote from: earplay on 2 Apr 2010, 01:47 pm

I must admit that I didn't attend closely enough to know when this happened. As I said, it takes about a minute. In that time, I would listen for a short period, then shift my attention to something else and let the B1 break-in. So, I don't know which change caused the problem.

The B1 has two electrolytics, so I was thinking one per channel. In that case, I thought, an electrolytic could go bad and not affect the other channel. But, I know I could be wrong in my assumptions there.

I do suspect my soldering of the volume pot because I can't see the rear connections very well. The legs did not align precisely with the holes, so I had to bend the legs somewhat. The rear legs do not protrude through the holes, so I may have a problem there.

I'll remove the pot and try to rejoin it to the board. Also, my afternoon is committed elsewhere, so I may not be able to fix this until tomorrow, when I have good light. I'll wire the pot to the board instead of soldering it directly. Then I can be sure my joints are good.

Will report back. Thanks again! Have a sunny day.

It cannot be the electrolytics as they supply both channels, if it is a dodgy joint then something would have to get fairly hot for it to have an effect.

A Sunny Day? In England?? In Spring???

walkern · « **Reply #172 on:** 2 Apr 2010, 05:02 pm »

Some electrolytics are polarized, and you could have one in backwards? I did this once with a dac kit, and the backwards cap would get SUPER hot fairly quickly and then give out. As soon as I installed it correctly everything worked like a champ. Just a thought.

Neil

earplay · « **Reply #173 on:** 3 Apr 2010, 11:01 pm »

Well, heat build-up could explain the problem, but everything stays cool. Plus, now the distortion is immediate. I did remove the pot and resoldered it with wire leads to assure that the connections are good.

Of the few things I know, I did get the electrolytics installed correctly by aligning the stripe on the cap to the stripe on the board.

Thanks, all. I may have blown a jfet. So I've been told. I wouldn't know and I don't have high confidence in my cheap DMM. Maybe too little confidence. Plus, it is hard for me to get a reliable check because I cannot hold the leads steadily enough. Nerve damage in my hands causes them to be too unsteady at this small scale.

Maybe I should just order a couple or four and get it over with. Well, get that part of the hunt over with.

xecluded · « **Reply #174 on:** 4 Apr 2010, 04:34 am »

What is the minimum voltage requirement for the (2) 10uf caps and (2) 1uf caps. Would 63VDC be to low?

sondale · « **Reply #175 on:** 4 Apr 2010, 05:41 pm »

Quote from: xecluded on 4 Apr 2010, 04:34 am

What is the minimum voltage requirement for the (2) 10uf caps and (2) 1uf caps. Would 63VDC be to low?

No - more than adequate - the psu should be delivering no more than 18vdc.

xecluded · « **Reply #176 on:** 4 Apr 2010, 06:58 pm »

Cool. It's all done now. Much easier than I thought and the best part is it works beautifully the first time i plugged it in. This is my first built ever. Many thanks everyone who helped to make this build happened.

wushuliu · « **Reply #177 on:** 5 Apr 2010, 08:14 pm »

final build pics w/ enclosure on page 5...

wushuliu · « **Reply #178 on:** 5 Apr 2010, 08:15 pm »

Quote from: xecluded on 4 Apr 2010, 06:58 pm

Cool. It's all done now. Much easier than I thought and the best part is it works beautifully the first time i plugged it in. This is my first built ever. Many thanks everyone who helped to make this build happened.

Sexy!

Mariusz · « **Reply #179 on:** 5 Apr 2010, 08:46 pm »

Quote from: wushuliu on 5 Apr 2010, 08:14 pm

final build pics w/ enclosure on page 5...

Very nice.

Great project.

Hope that many guys will benefit from this build.

Mariusz