Sunday, June 8, 2014

BHL Phono Preamp / WAC -49- #2 with Pyramid capacitors

I built another one of these using basically the same design...see my older post for the layout and general plans if you want to do one.  This time I used vintage USA Pyramid paper-in-oil capacitors for the 1 uF coupling caps.  The sound is even fatter and smoother than the standard Russian caps.  Ever so slightly, of course, but I appreciate the difference.  I think cap choice makes a pretty big difference in a preamp like this, I've read other builders say the same.  One guy used cheap panasonic film caps I think and it didn't sound as good to him.  This is no place to skimp when buying parts.  After all, this is an audiophile piece of equipment.  I had to sand the leads on the big caps clean because there was wax and junk all over them.  They soldered up fine, and work perfectly, despite their old age.  The best part is how cool they look, obviously, and the nasty wax coating that's all over them.

The other difference this time around is I used 100 uF bypass caps on all four JFETs, in parallel with the 50 ohm resistors.  The output is nice and high and easily matches a CD or MP3 of the same material in volume.  I would say that this is an essential modification to the stock BHL unit, I don't know why he didn't design his kits with more volume.  The level with no bypass capacitors in place is just not adequate.  The nice part about working on stripboard like this is it's easy to fit new parts like that, although a redesigned layout with the 100 uF caps specifically placed would probably be more elegant and not so tight.

This thing truly sounds great, and is very quiet.  The next step will be to build a dedicated 20-30 volt regulated DC power supply, and to finally ditch the old Technics direct drive for a better turntable.  I've got my eye on the Audio Technica LP1240 and various Shure and AT cartridges.

I gave the old one to a friend in need.  Things are sounding good in here.

No comments:

Post a Comment