Thread: Preamp build

I am in the process of obtaining the parts to build a Pass Labs B1 preamp/buffer for my son to pair with his Parasound A21 amp.

I am using Mundorf Mcap Supremes and Clarity ESA's for caps (It was between the ESA's or Obbligoato Golds which have more air, transparency and detail but less bass). My budget for caps was $100. For resistors I am using Audio Note Tantalums, Riken Carbon (in the out put stage) and Takman Rey's along with Tx 2575's ( input stage). I am putting in a 100k Ohm Remote controlled Alps volume pot (I prefer a 50k Ohm but I cant find the Alps in a motorized version in that value). For a power supply I am going to start with a 24v wal-wart. My son wants a warmer, slightly colored darker sound.

I will try and post pic's as it progresses. It should be fun. If all goes well, I will tackle the the Pass Pearl B2 phono preamp.

Will you post pictures as you go along?

Originally Posted by Mike

Will you post pictures as you go along?

I sure will. I will start the build in about 2 weeks as I have to go to Indianapolis for a conference and I have to order a few more parts along with the Metal case, remote control volume pot and board which will come from from Hong Kong-

http://diyclub.biz/catalog/product_i...roducts_id=591

I am going with silver to match the A21 amp.

Here are pic's of my build. The preamp sounds great. Have had it done for about 2 weeks-

Nice job, Larry. Would love to hear it. Keep us updated on it's sound.

Originally Posted by Shadowfax

Nice job, Larry. Would love to hear it. Keep us updated on it's sound.

Thanks, The wiring looks a little haphazard because the chassis that I bought was pre-drilled and it does not jive with the layout of the board.
Next up is to add a torroidal power transformer and swap out the volume pot for a remote controlled pot.

It sounds better than the Pass X1 preamp that I had which sold for $6K. It is much more musical with deeper bass and a more textured midrange. The mid range is where the money is on the B1. It is full, lush, smooth yet transparent and detailed at the same time. It has excellent air with a very wide and deep sound stage. Bass is powerful and there is a little bit of bloom. It leans just a hint on the warmer side of neutral which was by design with the caps and resistors used. I have about $300 invested in the B1.

The sound is really coming along as the hours pile up and the Mundorf and Clarity caps break in. I found an 18vdc external linear power supply for $100 here in the USA. I choose it over going with a torroidal because of the potential for RF or EMI with it. The Linear PS will be external. Next up is to add a 50kohm TKD volume pot with remote control pcb to replace the Alps Blue Velvet pot and to rewire things with twisted wire and clean things up a bit since I have to move the board around. I didn't want to start out with the linear PS and remote TKD pot without knowing how it would sound. The remote pot and board is about $150. It is a much better pot and it should improve the clarity. Same for the PS. I am going to add a 3rd input as well.