November, 2010

How many times can I get bitten by the audio bug?

Well, I've been on the audio hiatus for quite some time now. I estimate it's been about 9-10 years since I sat down and enjoyed some music. Must be related to the having children thing and the spouse approval factor. Well the bug bit me!! I first found my old Magnaplanar MMG's in my parents house stored in the back storage room and just covered with cob webs and installed them in the family room hooked up the the home theater system. I didn't install them earlier probably because i was afraid the children would damge them. The worst was when I found out that Matthew had put his Thomas trains into the port of the subwoofer. It was difficult to get out, but became easier with a pair of chop sticks.

After the MMGs I dug out my old Dynaco ST-70 tube amp and my Audio Note Tube preamp. I had purchased the ST-70 used when we were in Memphis circa 1995 via a list serv. I then upgraded some of the parts via a upgrade kit from the now defunct Parts Connection. The upgrade consisted of some teflon silver wire, some new capacitors and resistors and a diode. It had old Mullards and some Sovtek 7199's and it sounded great. I soon then purchased the Audio Note Preamp kit when went together nicely and complemented the Dynaco.

This time around I bought a new VTA driver board that uses 12AT7 driver tubes and also bought some Electro Harmonix 6CA7EH power tubes. Installation went well but when I initially installed the old Mullards, one of the tubes would not bias. It would build up voltage but around 25 mA, it would then drop to zero. I initially thought it was a bad connection somewhere, but when I moved the tube to another location the problem followed so I deduced that it was a bad tube. How come I didn't hear the difference before the upgrade? I then installed the 6CA7 tubes and life was good. Now since the VTA was the high gain version, now my preamp was a bit sensitive and a minor volume adjustment would be a large audio change. Now my decison was between getting an attenuator or modify the driver board to accomodate the low gain parts which would mean changing some resistors and the tubes to 12AU7's... decisions!!!

The other bug that bit was for a pair of new speakers. I had built the audioreview.com bookshelf speakers from Ed Frias in 2001, but the speakers were no longer avaialable. There were modified plans using Sea drivers, but I wanted a tower speaker which I could convert the plans to, but Parts Express had a DIY project in their flyer that caught my eye a couple of months ago. These plans were enetered into the Iowa DIY competition and got 2nd place. Not only did it get 2nd but cost about 10x cheaper than it's rivals. Though I trust Ed Frias' ears I wanted something new and a challenge. The PE speakers were called the Copper project due to their copper finish, designed by Marty Hafenbreadl. It is a tower design and will require some wood work. I've purchased all the electronics necessary so now it's building the cabinets.

I have the following:
circular saw
drill

I have purchsed
straight edge for cutting wood
circle cuting jig

need to buy
router
router bits

SO the saga continues