Nelson Pass B-1 preamp kit

wushuliu · « **Reply #380 on:** 7 Jul 2010, 07:53 pm »

I didn't do a tutorial for the DCB1, but I will do a small one for matching the LEDs and fets as this is probably the biggest stumbling block for the build to a beginner. Very easy, just need a multimeter.

Also, I will do a tour of the first DCB1 I built. I will also try to hot-rod it. I just need to get a proper enclosure first.

daniloreyes · « **Reply #381 on:** 7 Jul 2010, 09:18 pm »

Nice Build. That case looks awesome, whats the brand?
I like the idea of the integration, while trying to solder the RCA connectors was wondering the same, too many connections, welding etc and then adding interconnects (which by themselves have more connections) when it can be done one time and for all.
I'll probably end my two projects and then will do an integrated one. My B1 is looking cool, will put pics soon too.

wushuliu · « **Reply #382 on:** 8 Jul 2010, 04:51 am »

Quote from: daniloreyes on 7 Jul 2010, 09:18 pm

Nice Build. That case looks awesome, whats the brand?
I like the idea of the integration, while trying to solder the RCA connectors was wondering the same, too many connections, welding etc and then adding interconnects (which by themselves have more connections) when it can be done one time and for all.
I'll probably end my two projects and then will do an integrated one. My B1 is looking cool, will put pics soon too.

It's a gold alodine Par-Metal enclosure...

earplay · « **Reply #383 on:** 8 Jul 2010, 05:41 am »

sondale,

I just saw your post asking how I was getting on. I've got too many irons in the fire right now to do the B1 build. I will keep you posted, though, as I said I would. I see my reminder every day to do just that. Thanks for asking, though. I haven't forgotten.

Besides being busy, I'm kind of waiting for the many modification ideas to percolate in the thread.

I really don't need the B1 until cooler weather returns to south Florida. That will probably be in mid-October or November. I will use the B1 to drive my tube amp which puts out a lot of heat. The cozy glow of tubes is nice in cool and overcast climes, but the last thing I need in south Florida is one more reminder of the ^%$&*(^ heat. Just to give you an idea, the heat index (temp x humidity) will be over 100 degrees Fahranheit for five months.

In hot weather, I use my massaged Sonic Impact Super t-amp. Frankly, I'm surprised at its performance. Compared to "giant killers" I have owned (Glow Amp One w/NOS Mullards, MiniWatt w/upgraded tubes and the cap mod, Kingrex with full Audiomagus mods) it's no contest. I stumbled onto a formula that kills the giant killers. So it's cool runnings for me. I only wish I could get my hands on another one because there are a few other tricks I want to try.

I'll stop. I think I getting off topic. My mind wanders in the heat!

walkern · « **Reply #384 on:** 8 Jul 2010, 07:27 pm »

A little off topic, but I wonder what the unused secondaries (the taped off ones) are on the Class D amp torroid, and whether or not they could be used to power the DC B1? If there were a couple of 12V to 15V secondaries there, you might be able to get rid of the second (B1) transformer, and clean things up.

Just a thought?

Neil

wushuliu · « **Reply #385 on:** 9 Jul 2010, 08:38 am »

Quote from: walkern on 8 Jul 2010, 07:27 pm

A little off topic, but I wonder what the unused secondaries (the taped off ones) are on the Class D amp torroid, and whether or not they could be used to power the DC B1? If there were a couple of 12V to 15V secondaries there, you might be able to get rid of the second (B1) transformer, and clean things up.

Just a thought?

Neil

The classdaudio toroids come w/ unused secondaries now?

Nick77 · « **Reply #386 on:** 9 Jul 2010, 03:43 pm »

Quote from: Nick77 on 3 Jul 2010, 07:40 pm

Wushuliu thanks for the update on the dcB1, im sure it has to sound better or it wouldnt exist but this B1 is absoluely blowing me away. It has taken over 150 hrs to finally open up which has been very fustrating but worth the wait. I used carbon resistors in the signal path and i kept wanting to remove 2 if not all cause it sounded so lifeless and muted. Well i heard from several buddies that carbon resistors can take 300 hrs to break in so i decided to stick it out and i am glad i did. What i am hearing now is a VERY smooth warm yet detailed presentation that feels like an expensive tube preamp. I am in love, this little simple design rocks. Thanks again Wush for sharing, i would not have attempted it without your tutorial.

UPDATE:
Well i decided to give this close to 300hrs break in as several subjested but it remained to warm and syrupy for my taste. I removed the 2 carbon input resistors and replaced with prp metal fim and it sounds much more lively. A real good balance for anyone looking for a slightly warmer presentation.

Should have heeded Wushilui's warning of potentially to much of a good thing. hehe
Installing just a pair of carbon's on the output is a nice touch though.

walkern · « **Reply #387 on:** 9 Jul 2010, 04:03 pm »

Quote from: wushuliu on 9 Jul 2010, 08:38 am

The classdaudio toroids come w/ unused secondaries now?

Mine came with the blue and green wires (which were used for the Class D power supply board) and 2 or 3 additional wires (were brown if memory serves) which were NOT to be used, and needed to be clipped or taped up so they didn't short out or bump into anything conductive. I vaguely recall some folks asking about them early on in the Cheap and Cheerful Class D amp thread. I wouldn't even begin to know how to measure them... and hence my inquiry.

Okay, I re-read the Class D thread, and on page 13 they get mentioned, and on page 14 apparently Tom indicated that they are 12V secondaries which could be used for a secondary project, but are NOT used for the Class D amp. Apparently the early Antec transformers did not come with these, and the later 400VA models did. Sorry for the confusion.

Neil

wushuliu · « **Reply #388 on:** 9 Jul 2010, 04:36 pm »

Quote from: walkern on 9 Jul 2010, 04:03 pm

Mine came with the blue and green wires (which were used for the Class D power supply board) and 2 or 3 additional wires (were brown if memory serves) which were NOT to be used, and needed to be clipped or taped up so they didn't short out or bump into anything conductive. I vaguely recall some folks asking about them early on in the Cheap and Cheerful Class D amp thread. I wouldn't even begin to know how to measure them... and hence my inquiry.

Okay, I re-read the Class D thread, and on page 13 they get mentioned, and on page 14 apparently Tom indicated that they are 12V secondaries which could be used for a secondary project, but are NOT used for the Class D amp. Apparently the early Antec transformers did not come with these, and the later 400VA models did. Sorry for the confusion.

Neil

Interesting. If the secondaries are 12-0-12, then they can be used with for a DCB1.

walkern · « **Reply #389 on:** 9 Jul 2010, 06:52 pm »

That's exactly what I was thinking... which is often quite dangerous.

wushuliu · « **Reply #390 on:** 13 Jul 2010, 03:12 am »

I realized today my DCB1, which had an output impedance of 220 ohm was probably causing slight oscillation in the HF (persistent treble sizzle, reduced bass). My regular B1 had 330 and I had no problems with my classdaudio amp, but just an FYI to listen for that if you decide to go that low. In my case it was slight but prominent enough that I spent all day hunting down the cause.

And I thought it sounded good before...

daniloreyes · « **Reply #391 on:** 14 Jul 2010, 05:51 am »

Ok almost done,

Only issue is that the LED does not lit, no voltage.

How ever the sound is ok, very very clean and smooth.

used Cardas connectors, Cardas solder, western electric wires, Elna 12,000 uf 65v caps, Janzen MKP caps, and Alps 100k pot.

Big Elnas

wushuliu · « **Reply #392 on:** 14 Jul 2010, 08:14 am »

Quote from: daniloreyes on 14 Jul 2010, 05:51 am

Ok almost done,

Only issue is that the LED does not lit, no voltage.

How ever the sound is ok, very very clean.

used Cardas connectors, Cardas solder, western electric wires, Elna 12,000 uf 65v caps, Janzen MKP caps, and Alps 100k pot.

Another one down! Looks great!

Why did you choose the 100k pot?

daniloreyes · « **Reply #393 on:** 14 Jul 2010, 02:46 pm »

I used the 100k because Nelson Pass recommended anything from 25k to 100k. I just found 100k easier to get at the moment.
Sound should be the same, only percentage of volume will change, right?

I have another set of components (with PRP and Daytons caps) and will load them to a PassDIY (original) board to see the differences.

One detail I don't like is we cant adjust for bass and treble like a normal preamp, yes, I know we want pure sound, but aren't we changing caps and resistor brands to massage the sound to our liking? LOL

Note: don't use solid core wiring as it seems they break easily, I used stranded western electric NOS wiring.

Now to complete my classdaudio amp (using Cardas wires!!!).

current gear- Music Hall 25.2 cd player/Pass B1/Denon POA2200/Monitor Audio RS6= sweet sound!!!

face · « **Reply #394 on:** 14 Jul 2010, 11:29 pm »

Quote from: wushuliu on 2 Jul 2010, 01:23 am

Just an update on the DC Coupled B1: The sound has settled into a very open, easy going delivery. As sondale mentioned it is more open and transparent than the regular B1. Audibly, audibly so. It is also more engaging - maybe the term is musical? - than my battery run B1, which itself is terrific. I find myself having a hard time analyzing it as my mind wanders and I forget to skip to other demo tracks. Get lost in it pretty easily. Really involving. Not really sure how to describe the improvement except that it's absolutely worth it. I would love a comparison with higher priced gear...

The best cap is no cap.

wushuliu · « **Reply #395 on:** 15 Jul 2010, 12:03 am »

Quote from: face on 14 Jul 2010, 11:29 pm

The best cap is no cap.

I want to know how the heck you fit those massive 10uf Clarity MR's into your B1.

Have you heard the DCB1?

Bemopti123 · « **Reply #396 on:** 15 Jul 2010, 01:16 am »

Is there something special about the WE cables that were used for the wiring above? There is plenty of NOS/used WE cables in Ebay and I wonder if there is something to be gained by using such wire. It is a mystery to me....asides from the fact that it is covered with cotton or some cloth material....a la JPS.

face · « **Reply #397 on:** 15 Jul 2010, 02:31 am »

Quote from: wushuliu on 15 Jul 2010, 12:03 am

I want to know how the heck you fit those massive 10uf Clarity MR's into your B1.

Have you heard the DCB1?

They barely fit.

No, I haven't heard the DC yet. Maybe I'll get in on one of the GP's.

daniloreyes · « **Reply #398 on:** 15 Jul 2010, 07:26 am »

Quote from: face on 15 Jul 2010, 02:31 am

They barely fit.

No, I haven't heard the DC yet. Maybe I'll get in on one of the GP's.

HEHEHE those caps have a nice B1 sticked to it!!!

porfido · « **Reply #399 on:** 15 Jul 2010, 01:36 pm »

Hi everybody!
First of all, sorry for my terrible english, I'm writing from Italy....

Second, thank you so much for this very useful thread!

I finished my B1 some months ago and I'm very satisfied, but I would ask you if someone tried batteries psu with this buffer and if this kind of supply gives any advantage on, for example, switching supply like the one I'm using....
Thank you very very much!

P.S. Some pics of my B1: