B1 builders thread

[vitalstates]

heres the link cos I'm not sure how to get more than one big photo on a post...

Vitalstates- Amplifiers


Ed

[jonsmith]

Hi to one and all, with special thanks to Mr. Pass:

A couple of photos of my B1. Finished it last Thus./Friday and have been listening pretty much constantly since.

Note the "fabricated from billet magnesium knobs" and the hickory case made from a tree that fell in my father-in-law's woods 25 years ago.

Am hearing things I've never heard before, and some things that used to be prominent are farther back in the mix than before. Bass is clearer, not as resonant. High end is much softer and more like I remember records sounding like.

Note that I am powering a GFA 555 amp that I bought in 1986... It sounds a lot more linear at both lower and higher volumes--less "confused." Would have never been able to afford a new preamp, so this was really a great treat to get such an improvement for little or no money! Thanks for your generosity Mr. Pass, I have really enjoyed my Adcom gear that you designed, and now I can afford some of your other stuff (if I build it myself!)

Jonathan Smith

[Nelson Pass]

We aim to please.

[Beftus]

... and all that audio nirvana is powered by just two 9 volts PP3 batteries? Must get me some of those!

[jonsmith]

The clerk at Radio Shack _did_assure me that the batteries were audiophile grade.

The preamp is now sporting a brand new hewlett packard regulated 20 V power supply from Wal Mart, currently on sale.

I think it sounds just as good, and particularly better than when the circuit is running on 6 volts, like when your audophile batteries are giving up the ghost.

[Rodeodave]

Here's my take on the B1. It will be the input-buffer of an integrated amp I'm building for a friend of mine. I somehow like to p2p and make connections with the components' leads. Half the solder joints.

Today I'll add the resistors. Cute amp.

Edit: In the hand-drawn schematic half the caps (Panasonic FC 2200uF50V) have wrong polarity, yes. I was used to draw bipolar supplies, so...
But they were installed correctly as you can see in the pic.

[Rodeodave]

And here's the data from matching the 100 2SK170BL.
First histo shows I_dss abundance with bins 0.04mA wide.
Second shows same with bins 0.01mA wide.
Third pic shows data.

The JFETS used have (7.68,7.68,7.67,7.66)mA I_dss.

Edit: I ended up with 26 unmatched JFETs, the others are matched within 0.01mA up to 0.04mA, so 37 pairs in total.

[Rodeodave]

My B1 is finished, probably. But as Papa once said:

"check everything twice, (once in the evening, once in the morning)"
(Zen Variations #8, page 8)

I'll sleep over it and fire it up tomorrow.

[jleaman]

good work guys, looking good

[studeb]

Here is my build.
Been running for a few months now, I do enjoy it very much.
The PS is a regulated 18V wall wart. PassDiy board and pretty much stock parts.
Thank you Mr. Pass and associates that are leased/rented or otherwise indebtured.
The downside is that now i need a new phono amp.......