Monday, July 16, 2012

Two Steps Forwards, One Backwards

After getting back home from a long Saturday (trip to nursury, dinner, concert) I thought I'd catch up on a few audio issues in the master bedroom.

Ever since I set up the Linn Sondek turntable system a few months back, I haven't had a 24 bit ADC to digitize the output of my Denon 3910 DVD-Audio/SACD player.  I moved the Behringer DEQ 2496 over next to the turntable to keep the analog lines short.  So I had to plug the 3910 straight into the Tact RCS 2.0 analog inputs, which are notoriously 16 bit (or at least 16 bit performance).  To add insult to injury, I also had to attenuate the DVD player output with a 6dB attenuator to be sure it did not overload the maximum 1.5V input of the Tact.  Actually, 3dB would have been sufficient, but when I set this up I had run out of 3dB attenuators.

To fix this, a few weeks back I have moved the MSB PAD-1 into the bedroom, but hadn't hooked it up.

Here's a list of things I ended up doing:

1) Removed Acurus L-10 preamp, now possibly not working (or at least LED not lighted).

2) Removed Yahama T-85 from underneath Tact.  The T-85 has issues and I haven't used it in several years.  It was finally convenient to remove the T-85 after I removed all the stuff on top of the Tact.

3) Vacuumed, vacuumed, vacuumed (top of Tact, MSB, Aragon and rack)

4) Hooked up the MSB, including its power adapter, and hook its AES/EBU output to the Tact (#5).

3) Moved the Aragon 28K preamp on top of the MSB.  It had been over near the phonograph system, but was not being used.  I had tried using it instead of the tube preamp for the Panasonic strain gauge cartridges, but it didn't work well in that application, nevertheless it had stayed there.

4) Hooked up the 28K to the analog output of the Denon.  Only the Denon is now hooked up.

5) Removed old analog line from TV to Acurus.  Apparently I had set up this line because the digital link from TV to Tact was once not working well.  I figured out why also (see below) and fixed it.  This line used a long interconnect, two 3dB adapters, and a Radio Shack isolation transformer.

6) Moved 30 foot Toslink connection from TV to Behringer used for phono system.

7) Extracted M-Audio CO2 from living room and connected to Tact with coax (finally using fancy radio shack coax, one from BJC was too stiff).  This adapter converts toslink to coax digital so I can use one of the 3 coax digital inputs on the Tact.

8) Tried BJC toslink from TV to CO2.  Very intermittent, usually not working unless I wiggled the cable at the input to CO2.  Now I remembered I had this problem before.

9) Extracted a 2nd 30ft toslink cable from behind the sofa in living room.  That second cable has been ambushed there by a snarl for several years.  Using that cable, the CO2 worked fine, so now the digital connection between TV and audio system works fine, and also allows remote switching to the digital connection between phonograph and audio system.  Previously I had to manually switch the one working 30 foot toslink cable I had between TV and phono system, which didn't encourage me to play more records.

10) Adjusted gain on 28K so that Denon would not clip MSB.  My first test was playing a Chesky jazz disc 'Havana' over and over and noting the peak level.  That was a very time consuming test, but the disc was already in the player.  Later I used the Stereophile test disc 2 on track 17 and noted the "average level".  Finally I used the 19+20K distortion test, turning off the DCX so as not to play through speakers.  With that test playing at 0dB, I had average level about -3.5dB with volume control at about 2:30.  Peak level was just above -20dB, but I don't think that is a problem.  I need to make a better test disc for this purpose.

11) Finding that I couldn't see the Denon on my TV, I reconnected the S-Video cable that goes through Isomax transformer.

12) I played a multichannel SACD and was finding that despite setting SACD control to stereo, the indicator still showed multichannel output.

13) Fiddling with the Denon setup menu, I found it was necessary to turn the Denon-link off in order to adjust the audio from multichannel to stereo.

14) I listened to several discs, notably Hanson conducts Hanson, as background music as I was working on stuff.

15) Once I got the TV working over the 2nd toslink cable, I ran that for several hours to make sure it was working without cutouts.  It was playing a Nova special on string theory.

16) Tested phono system which I haven't used for a couple months.  The Linn appears not to start.  The pushbutton light goes out quickly after the start button is pressed.

****  So I went to a lot of work to make it possible to switch digital inputs from TV to Turntable and back, and then guess what, the turntable stops working !!!

I may fiddle with the Linn a bit more.  Also this might be a good time to check out the Sony turntable.  I never actually inspected the Sony circuitry, I just disconnected it at the first sight of bad operation.

It's sad that my phono system isn't working again.  But it seems I like to play DVD-Audio and SACD discs more anyway.