Pass Labs B1 preamp build

I am currently obtaining the parts to build the Pass Labs DIY B1 Preamp Buffer. $40 for the board and JFET's from Pass. I hope to have it built in the next 30 days or so. So far I am upgrading the recommended stock parts. I want a preamp with good bass, air, transparency and detail that leans to the warmer side of neutral. I am putting in Riken Carbon resistors in the out put stage to warm things up and some Audio Note Tantalum resistors for their smooth sound. A TX2575 reisistor will go in the input stage for its clarity, resolution and dynamics.

Caps are going to be Obbligato Golds, Clarity ESA's or AmpOhm's Aluminum Paper In Oil or some combination of these. It all depends if the AmpOhms will fit. They are a cheaper alternative to Mundorf PIO but with similar sound. I would like to use Jupiter wax caps but they are expensive.

I am hoping to find a nice remote volume control. Probably an Alps.

If this build goes well I will probably build the Pass Pearl 2 phono preamp which is a bit more complex and more expensive due to the 2 boards and JFET's costing $200.

I will try to post pic's of the build which I hope to start in about 2 weeks as parts are arriving every few days.

Way to go. If it ends up sounding better than the BAT you'll be building all of us one :)

That's great. I had once or twice considered building a B1, and I'll be looking forward to your updates for sure

I was daunted mainly by the volume control issue, (since I insist on remote control), and the need to buy or build a suitable case/cabinet to house it. I'll be very interested in your solutions to these problems.

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Originally Posted by Feanor

That's great. I had once or twice considered building a B1, and I'll be looking forward to your updates for sure

I was daunted mainly by the volume control issue, (since I insist on remote control), and the need to buy or build a suitable case/cabinet to house it. I'll be very interested in your solutions to these problems.

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Here is a link to a DIY store for a chassis with a remote Alps pot-

DIYCLUB

DIYCLUB


I am going to buy the chassis in silver

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Originally Posted by blackraven

Here is a link to a DIY store for a chassis with a remote Alps pot-

DIYCLUB

DIYCLUB

I am going to buy the chassis in silver

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Those look like good choices. Also that Hong Kong site looks a bit more confidence inspiring that some.

Are you going to need an input selector?

What are you doing about a power supply for the B1 and also for the remote control. The former needs an 19-24 VDC supply while the latter needs 9 or 12 VDC.

I am going to go with the recommended wall wart for the B1 which is 18 to 24v. I will have to use a step down voltage converter. You can find them for about $5. I will have my Electrical Engineer friend help me with that.

EPS240025-P5P CUI Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

Here is the actual part list for the B1. It's about $150 for the stock parts, but I will be using better Caps and some boutique resistors, about $250 in parts.

Nelson Pass B-1 preamp kit

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Originally Posted by blackraven

I am going to go with the recommended wall wart for the B1 which is 18 to 24v. I will have to use a step down voltage converter. You can find them for about $5. I will have my Electrical Engineer friend help me with that.

EPS240025-P5P CUI Inc. | Power Supplies - External/Internal (Off-Board) | DigiKey

Here is the actual part list for the B1. It's about $150 for the stock parts, but I will be using better Caps and some boutique resistors, about $250 in parts.

Nelson Pass B-1 preamp kit

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Yep, a wall wart will work fine. Come to that, I have a draw full of wall warts from defunct electronic equipment, including an 18.5 VDC power supply from long-gone HP laptop, plus enumerable 9 and 12 VDC units.

As I discovered after posing the question, there are also slightly up-market linear power supplies that are available for about $60. E.g. ...

15W DC18V Linear Power Supply PSU With Digital Display 110V OR 220V Available | eBay

http://i.ebayimg.com/00/s/NjQ5WDgwMA...TDWsD/$_57.JPG

Set-down devices are available and cheap, e.g. ...

DC DC Converter Step Down Regulator LM2596 Power Supply 3 30V TO 1 21 18V EA | eBay

I started my build of the B1 the other day. My soldering skills are coming back to me. I am going to teach my son how to solder and let him help build it. I will post pic's as the build progresses.

I went with Mundorf MCap supreme and Clarity ESA caps for the 1uF and 10uF caps.

In addition to the Riken Carbon (output stage) and Tx 2575 resistors (input stage) I am using Audio Note Tantalum resistors through out.

I have settled on an Alps Blue Velvet volume pot 50K. And I will eventually add a remote volume pot if I like the sound.

I am using 24g stranded copper hook up wire and Cardas Silver Solder for its low melting temperature.

Thanks for the update. I'll continue to follow you progress with interest.

Do you intend to use the B1 with your Pass amp? The B1 is single-ended obviously. It seems one could use TWO B1's to make a fully balance preamp; have you heard of anyone doing this?

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Originally Posted by Feanor

Thanks for the update. I'll continue to follow you progress with interest.

Do you intend to use the B1 with your Pass amp? The B1 is single-ended obviously. It seems one could use TWO B1's to make a fully balance preamp; have you heard of anyone doing this?

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Bill, I am building this for my son to use with the Parasound A21 that I gave him. He is currently using my AVA hybrid tube preamp. It will be interesting to see how the 2 compare. The B1 is supposed to have a lot of air and transparency. I will try the B1 with the Pass but I doubt that it would better the BAT. I could use the B1 as a buffer between the Pass and BAT to fix the slight impedance mismatch.

I have thought about buying 2 boards and making a balanced unit. It would be fun to try.

I have ordered this chassis in silver-

DIYCLUB

Lite A28 A Series Preamplifier General Chassis Amp Box Preamp Case | eBay

The case looks very good, especially since it includes most hardware.

Well, we completed the B1 and it sounds awesome in my son's system tonight. He is running it with my old Parasound A21 amp, PSB B6 speakers and a laptop computer using Bug Head and an Audio Quest Dragon Fly DAC with an AQ Jitterbug. The sound has excellent air and transparency with a wide sound stage. The background is very black and the clarity is amazing. Bass is tight, controlled and powerful with just a little bit of bloom. The midrange is very smooth and liquid but detailed at the same time with very good texture. Midrange and clarity seems to be its strongest point. Vocals, horns and piano sound real and alive. What really surprised my was how dynamic the sound is with it being basically a buffer with no gain. If I had to pick a weakness, I would say it is that the very upper frequencies appear to be pushed back or slightly rolled. That may improve as it breaks in over the next 50 hours or so. If it doesn't, I may replace the carbon Riken resistors in the output stage which were used there to lend a little warmth. But I have read that they can roll off the highs a little.

I have a friend who is an EE and he helped wire in the selector switch. He put the preamp on a scope and it spec's out well. The square wave was pristine and the frequency response was spot on 20-20K. I think that you would have to spend at least $1500 or more to get this kind of performance from a preamp. Overall it took his system to a new level of audio sophistication.

Next up is to get rid of the wall wart power supply and add a torroidal transformer and a remote volume control.

I built the preamp with about $300 of parts (the chassis and shipping was $110 and the boutique Mundorf and Clarity ESA caps ran about $100) but it could easily be done for about $150.

I will post pictures on Friday when I have the day off. I will also try the preamp in my reference system and compare it to my BAT preamp and report back.

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Originally Posted by blackraven

I will post pictures on Friday when I have the day off. I will also try the preamp in my reference system and compare it to my BAT preamp and report back.

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Great project. I'd love to hear one of these. Looking forward to your BAT comparison.

How much labor do you have into it? Thats usually way more than the cost of the parts. You could build and sell these units :)

Congratulations. I'm not surprised by the good results though.

Let us know if you make further changes or upgrades. Also I'll look forward to the BAT comparison when you get around to it.

Way to go. Maybe your next system you'll just build :)

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Originally Posted by Mr Peabody

Way to go. Maybe your next system you'll just build :)

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I am eventually going to try and build the Pass Pearl Phono preamp (the boards cost $200 compared to $40 for the B1) and maybe a Pass First Watt amp.

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Originally Posted by Hyfi

Great project. I'd love to hear one of these. Looking forward to your BAT comparison.

How much labor do you have into it? Thats usually way more than the cost of the parts. You could build and sell these units :)

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HyFi, I have about 5-6 hours of labor into it. I took time to test the values of all the resistors with my multi-meter. I also had to drill some holes in the chassis. In addition, I let my son help me build it so I had to teach him to solder.

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Originally Posted by blackraven

Well, we completed the B1 and it sounds awesome in my son's system tonight. He is running it with my old Parasound A21 amp, PSB B6 speakers and a laptop computer using Bug Head and an Audio Quest Dragon Fly DAC with an AQ Jitterbug. The sound has excellent air and transparency with a wide sound stage. The background is very black and the clarity is amazing. Bass is tight, controlled and powerful with just a little bit of bloom. The midrange is very smooth and liquid but detailed at the same time with very good texture. Midrange and clarity seems to be its strongest point. Vocals, horns and piano sound real and alive. What really surprised my was how dynamic the sound is with it being basically a buffer with no gain. If I had to pick a weakness, I would say it is that the very upper frequencies appear to be pushed back or slightly rolled. That may improve as it breaks in over the next 50 hours or so. If it doesn't, I may replace the carbon Riken resistors in the output stage which were used there to lend a little warmth. But I have read that they can roll off the highs a little.

I have a friend who is an EE and he helped wire in the selector switch. He put the preamp on a scope and it spec's out well. The square wave was pristine and the frequency response was spot on 20-20K. I think that you would have to spend at least $1500 or more to get this kind of performance from a preamp. Overall it took his system to a new level of audio sophistication.

Next up is to get rid of the wall wart power supply and add a torroidal transformer and a remote volume control.

I built the preamp with about $300 of parts (the chassis and shipping was $110 and the boutique Mundorf and Clarity ESA caps ran about $100) but it could easily be done for about $150.

I will post pictures on Friday when I have the day off. I will also try the preamp in my reference system and compare it to my BAT preamp and report back.

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Got some free time and since I was intrigued about Bug Head, I decided to download it and check it out. Got it to play my files, but the files stop playing in the middle of the song. Is there a tutorial that to tell me how to use it. I sort of just shot in the dark until I got it to play. It gave me 4 icons on my home screen but the one that looks like it will work acts like it is reloading the program each time.

Jack, what are the spec's of your computer - CPU type and model, how many GB's ram.

The different Bug Head icons all run bug head, the SQ versions take more computing and ram.

Try turning off your anti-virus when running bug head.

I can walk you through the settings. Also, what version of BH are you using.

I think that you have bug head set to play part of a song and then cut off. After you have turned on Bug Head and hit start you will get the play screen. At the top of the screen, just to the right of midline you will see a box that says LPF Free. If you put your pointer just 1-2mm to the right of the LPF Free box and left click, it should open up another menu (you may have to click a couple of times if you don't have the pointer in just the right area). In that menu you will see a box called Fade Off. This should be red, otherwise the songs will fade off after 80, 90 or 100 seconds. Also, at first you may want to have Stardust turned off if you want to load songs faster. Each level of Stardust improves the sound but the songs take longer to load and clear. Things take long to load because BH clears out the memory of junk and then loads the songs.

If you want to, you can call me on my cell phone. Just send me a pm and I will send you my number. BH is truly worth the trouble as it is lightyears better than JR and HQ player.

Regards,

Larry

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Originally Posted by blackraven

Jack, what are the spec's of your computer - CPU type and model, how many GB's ram.

The different Bug Head icons all run bug head, the SQ versions take more computing and ram.

Try turning off your anti-virus when running bug head.

I can walk you through the settings. Also, what version of BH are you using.

I think that you have bug head set to play part of a song and then cut off. After you have turned on Bug Head and hit start you will get the play screen. At the top of the screen, just to the right of midline you will see a box that says LPF Free. If you put your pointer just 1-2mm to the right of the LPF Free box and left click, it should open up another menu (you may have to click a couple of times if you don't have the pointer in just the right area). In that menu you will see a box called Fade Off. This should be red, otherwise the songs will fade off after 80, 90 or 100 seconds. Also, at first you may want to have Stardust turned off if you want to load songs faster. Each level of Stardust improves the sound but the songs take longer to load and clear. Things take long to load because BH clears out the memory of junk and then loads the songs.

If you want to, you can call me on my cell phone. Just send me a pm and I will send you my number. BH is truly worth the trouble as it is lightyears better than JR and HQ player.

Regards,

Larry

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I have a Dell M1330 laptop. It's running an Intel Core 2 Duo Cpu, with 3.00 GB of ram.

The Fade off was in red, should anything else be in red?

It looks like I'm running BH 5.90 version.

Jack, I don't think that you have enough horse power with that computer especially with only 3gigs of ram. I would try one of the non SQ versions of BH and don't use stardust mode. Also, do you have a good usb cable? Cheap ones, especially longer than 6 feet can drop out the signal. I am not sure that you could even run HQ player with that computer. Both programs are cpu intensive and BH is also ram intensive.

I have 3 laptops. 2 have first and second gen I3's and BH runs fine with both that have 4 and 8 gigs of ram. My reference laptop is an I-7 with 16gb of ram. BH recommends an I-7 and 8gb ram or higher for best sound quality. I noticed a slight improvement in sound with the I-7 and 16gb, but both I3's sound great.

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Originally Posted by blackraven

Jack, I don't think that you have enough horse power with that computer especially with only 3gigs of ram. I would try one of the non SQ versions of BH and don't use stardust mode. Also, do you have a good usb cable? Cheap ones, especially longer than 6 feet can drop out the signal. I am not sure that you could even run HQ player with that computer. Both programs are cpu intensive and BH is also ram intensive.

I have 3 laptops. 2 have first and second gen I3's and BH runs fine with both that have 4 and 8 gigs of ram. My reference laptop is an I-7 with 16gb of ram. BH recommends an I-7 and 8gb ram or higher for best sound quality. I noticed a slight improvement in sound with the I-7 and 16gb, but both I3's sound great.

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That very well might be the problem. I bought the laptop just to use as a music server as it has all my HDTracks downloads on it. I use JR21 normally with no problem. I might try my other laptop as it's much more powerful and still has some music files on it.

It's a HP Pavilion DV7, with an Intel Core i7 -2670QM processor and has 8 GB of ram.

My USB cable is a Wireworld Starlight 7

I've heard nothing but great reviews about the Pearl!

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Originally Posted by Jack in Wilmington

That very well might be the problem. I bought the laptop just to use as a music server as it has all my HDTracks downloads on it. I use JR21 normally with no problem. I might try my other laptop as it's much more powerful and still has some music files on it.

It's a HP Pavilion DV7, with an Intel Core i7 -2670QM processor and has 8 GB of ram.

My USB cable is a Wireworld Starlight 7

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That computer will have no problems at all as my I-3's run BH without problems. Let me know if you still have problems and we can talk. I use the WW Starlight 7 as well but I would love to have the Platinum. The Starlight sounds veiled in comparison, however my Regen narrows the gap between the 2 cables and makes all cables sound similar.

By the way. B1 is smoothing out. I can say without a doubt that it sounds better than the Pass X1 preamp that I had. It is more musical and has better bass. The X1 sounded sterile. That is saying a lot since the X1 sold for $6K and I built the Pass B1 for $300.

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Originally Posted by blackraven

That computer will have no problems at all as my I-3's run BH without problems. Let me know if you still have problems and we can talk. I use the WW Starlight 7 as well but I would love to have the Platinum. The Starlight sounds veiled in comparison, however my Regen narrows the gap between the 2 cables and makes all cables sound similar.

By the way. B1 is smoothing out. I can say without a doubt that it sounds better than the Pass X1 preamp that I had. It is more musical and has better bass. The X1 sounded sterile. That is saying a lot since the X1 sold for $6K and I built the Pass B1 for $300.

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Ran BH on my other laptop and no problem. It's a little awkward and redundant, but I'm sure some of that will fade as I become more familiar with the format.