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Thread: Nelson Pass B1 preamp build

  1. #111
    Bigman80 Guest

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    Quote Originally Posted by STD305M View Post
    Hi Oliver

    Ive been following this Thread with great interest, as you know I'm in the middle of a DC-B1 turbo build, not easy for me as i have no idea about electronics but I'm learning very quickly.
    Fortunately the board has the values of all the components. Iv tried where possible to order the best i can afford ie; vishay dale - Nichicon - Khozmo Series Attenuator Blah Blah Blah !!!
    Ive taken advice from yourself and Mr Firebottle ( thank you both ) and done a massive amount of research online.
    I will of course be needing a little more help to complete my project but have found working on my preamp very rewarding.
    Lets hope it sound as good as it looks.

    I cant wait to get it hooked up to my new Firebottle mono's when Alan completes them.

    Regards Steve
    Hi Steve,.

    It's a great preamp in its standard form and as you know, I will be putting a Turbo version together too.

    Some folks aren't convinced on the merits of parts such as the Dale and Vishay stuff but I Certainly am. Good move there.

    The Khozmo stepped attenuator is a fantastic bit of kit and it's been superb. It did take a number of hours before I felt it relaxed as at first I thought it sounded a bit stiff but I'm happy to report it isn't the case in the long term. Transparent and honest. Can't go wrong.

    Looking forward to seeing the finished article mate. Well done for having a bash.

    O

    Sent from my VKY-L09 using Tapatalk

  2. #112
    Bigman80 Guest

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    It's been some time since this thread got an update but seeing as it's been a bit of an experimental path, with upgrades and rebuilds done in great haste, I think a return to it and a brief summary of developments will be acceptable!

    After building the first itineration of the DCB1, selling it on and rebuilding another DCB1 with a more suitable chassis, it ran at 600mA for some time. This was always going to be a temporary thing as the real goal was to get it up to 1.2A.

    Running at 600mA certainly provided more of the best bits this preamp gives by opening up the soundstage and sounding even more transparent than my original one before we upped it's mA's

    STD305 (Steve) and I started to discuss what to do next. I wanted 1.2A so that's what we went for.

    The 1.2A was less straight forward to build than id have liked. For instance, the reported resistor values were in fact, well short of what was required to get 1.2A running through the board. I had to get some help from Alan, but as usual, he sorted it out.

    This build saw Steve and I deviate from the supplied kit in the form of swapping the brand of resistors. We were messaging daily on the status of our builds and looking for exotic parts to stuff the board with. Though the PCB kit is normally supplied with Dale Vishay resistors, We went for Audionote Tantalum resistors instead. I loved them instantly but Steve felt they were a little light on bass. Steve ventured off into ZFoil madness and more, even building an I'll fated dual moni DCB1 with zfoils in, but I kept mine running in. Eventually, they opened up and the bass was no issue. I felt the AN Tantalum were more transparent than the Dales and after some time, Steve came back to the AN, which I believe are still in situ.

    Steve and I discussed capacitors to replace the WIMA 0.22UF. At the time, i felt the WIMA were doing just fine but as usual, Steve went bonkers and bought bees wax and paper caps (I think). He really goes all out when he's on to something!

    He reported a very noticeable improvement. I remained with the WIMA until this week when I swapped mine out for some Obbligato Gold caps. I wish I'd done it earlier on.

    Today, I was absolutely convinced that this IS as good as any preamp I've ever heard. So, what's the best test of a preamp? Remove it and see what happens

    I decided to see what effect the DCB1 has on things by removing it from the chain altogether. This was only possible to do now that I have the Raspberry Pi and could control the volume via the Volumio app.

    From Pi directly to Krell.

    I listened to a fair few tracks and tried to notice whatever I could. Little notes, breaths, fret buzzes. Literally anything that COULD be masked by a lack of transparency.

    I put the DCB1 back in and listened again.

    Everything I had heard was still there BUT the DCB1 does have an effect but it's not on transparency. It's on the feel of the music. It gives it a bit more drive or potency, if you will. It's not a lot but I was using the pi to send a signal to the Krell via 2m of cable. With the DCB1 in place it felt like it was getting there a little quicker.

    Transparency and insight were absolutely unaffected and so too was tone. It was incredibly close to the sound when it wasn't there at all. So close, I'd challenge anyone to blind test it and pick between them.

    The other difference I noted was that the soundstage was a bit bigger through the DCB1 but I have no explanation for that at all.

    Overall, the DCB1 has been one of the best finds I've had in HiFi. I love mine to bits and now only have one thing left to do with it, and that is fit a power button. That should arrive this week. Pilot hole has already been drilled lol. Then the lid can finally be screwed on and left on.

    If you are in the market for a preamp, I absolutely recommend getting a listen to one.







  3. #113
    Join Date: Sep 2014

    Location: brighton uk.

    Posts: 4,737
    I'm jamie.

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    Why was the dual mono dcb1 ‘I’ll faited’?
    My System
    John Wood KT88 Amp.
    Paradise Phono Stage
    Sony TTS-8000 Turntable.
    PMAT-1010 MK6 Tonearm.
    Ortofon Cadenza Bronze
    Sony X555ES Cd Player
    Yamaha NS1000m Speakers

  4. #114
    Bigman80 Guest

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    Quote Originally Posted by karma67 View Post
    Why was the dual mono dcb1 ‘I’ll faited’?
    Steve can probably answer that more thoroughly but my understanding was that once he'd built it, under instructions given to him by the creator, the unit had a hum or ground loop or some kind of noise he couldn't get rid of.

    I believe he stripped it back to a single PCB and is now using it noise free.

    Shame because it would have been epic!

  5. #115
    Join Date: Jan 2014

    Location: london se6

    Posts: 823
    I'm AndyElectroNumpty.

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    Hi Oliver good to see the amp being improved , what effect did the Obligatos have on the sound?

    Cheers Andy

  6. #116
    Bigman80 Guest

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    Quote Originally Posted by smangus View Post
    Hi Oliver good to see the amp being improved , what effect did the Obligatos have on the sound?

    Cheers Andy
    Well, It's only my opinion but i feel the soundstage had improved vastly, almost like the odd noise or sound comes at you from an angle you didn't expect or hasn't done before. Transparency has improved. Its removed a thin film from the sound that i didn't realise was there. Bass had better detail, whilst leading edges are clearer which of course means the decay has improved too. I feel closer to the music and like i am able to pick out more. I didn't expect that from changing two capacitors.

  7. #117
    Join Date: Jan 2014

    Location: london se6

    Posts: 823
    I'm AndyElectroNumpty.

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    Thats interesting, something else to think about lol

    Sent from my SM-G950F using Tapatalk
    At the cutting edge of Numptyness!

  8. #118
    Bigman80 Guest

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    Quote Originally Posted by smangus View Post
    Thats interesting, something else to think about lol

    Sent from my SM-G950F using Tapatalk
    I know, it's a pain because everything costs.

    To be fair, I don't know why I was so surprised. I've experimented with caps in phonostages and found that some were clearly better than others. I didn't expect it though and it's always a nice moment when you make the right choice.

    The WIMA are decent caps but I've got Dale resistors, Audio note tantulum resistors, Nichicon gold caps, and SPOTFIRE wire throughout the DCB1 so really, I should've put better caps in from the start. Pleb!

    There's about 10-15 hours on the Obbligato and they sounded a little bassey in the early stages but that's evened out already. If they open up further after more hours, I'll be putting some in my Bigbottle phonostage too!

  9. #119
    Join Date: Jan 2014

    Location: london se6

    Posts: 823
    I'm AndyElectroNumpty.

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    When I bought the board I got 2 , my intention was always tobuse the 1st one as a learning experience (done!) and then use the 2nd one for better quality parts etc. So I've got this to look forwards to .

    Sent from my SM-G950F using Tapatalk
    At the cutting edge of Numptyness!

  10. #120
    Join Date: May 2017

    Location: West Sussex, UK

    Posts: 775
    I'm Steve.

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    Hi Oliver,
    Great write up on your progress.
    I've got a little respite so have decided to add to the thread.
    I've gone through several DCB1 builds including a very expensive dual mono build which was a little disappointing, only because i didn't have the skill to get to the bottom of quite a few issues it had.

    I've finally ended up going back to using a single board but stuffed full of boutique parts.
    Ive ended up having tried resistors from 6 manufacturers with audionote tantalums. They work really well and beat the Charcrofts by quite some margin.
    The buffer caps from Nichicon stayed but the Wima caps which are very good indeed were replaced with Jupier caps, they gave the whole sound a lift.

    The only thing i really would recommend is to experiment, I did at a huge cost but worth the effort even though it didn't work as it gave me the chance to see what works best.
    I'm also very lucky that when i split the dual mono and rebuilt 2 machines i recouped my costs and 2 people ended up with top quality preamps.

    Anyone putting together a dcb1, should budget allow should use tantlum resistors throughout and replace the 2 Wima caps for higher spec caps. Stay with the khozmo, Elma switch and get the best hook up wire you can find, I personally like Oliver's spitfire cable.

    Then just sit back and enjoy, very probably, the best preamp I've personally ever heard, knowing you built it yourself

    Regards Steve...
    Turntable; Rega p8
    Cartridge; Alpheta mc
    Phono Stage; Rega Aria, Bigbottle 3 mm/mc
    Amplifier; Rega Elicit
    Speakers; Rega Rx3

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