HELP! Talk me off the ledge. Tonearm Troubles!

[cabsvrt]

I am a smart guy, I have built many things and have worked on plus owned many turntables and tone arms. But this has me perplexed.

Background to this problem is: I am using a new (to me) VTL 5.5 Phono Tube Preamp. I was feeding it with a Denon DD and Yamaha DD turntable while I was building my new TT. On the new TT I started off with an ET 2.5 arm which I rewired all the way to the plugs, did everything the same as in the old arm, never had anything but hum problems, channels missing or what-have-you. Scrapped that plan for my sanity (until later) and went with a new Clearaudio Satisfy Tonearm which I know would work.

The Clearaudio's left channel wasn't working. Swapped the right and left.. left channels not working! Dropped the ground wire, no left channel! Plugged in the Denon and then the Yamaha. Stereo sound! Right and left. I used an AT Shibata stylus cart on the D & Y because it was similar to the Signet MR5.0 LC on the Clearaudio Tonearm.

I inserted an RCA extension cable to check for connector mismatch. Now right channel only for Clearaudio and Stereo for D & Y, again. There is continuity in the Clearaudio leads. WTF! I am PERPLEXED and typing this from the roof on my iPad. Don't let me jump!

[cabsvrt]

Just swapped carts, now left channel is playing on the Clearaudio... but with hum.

[singa]

Hi ,
If you claim you are smart then you know fault finding is
a logical process.You seem to take things for granted.For instance you
say continuity of leads for clearaudio tonearm is good but the fact is that
the left channel is still not working.Why is that?

In continuity testing with a meter you should be experienced
enough to know that when you have a break in the wiring ,flexing it a dlfferent way will temporarily make a contact and appear as good on a meter
so when you bend it slightly another way you loose the connection.

Isolate stage by stage and measure properly.Know that breaks
either break in th middle or crimp/solder ends of the wire (more common).
The tonearm has tiny parts and wiring so make sure your meter probes are
sharp and to have good contact you may need to scratch the surface to get
to the metal and not the oxidised layer of the connector(which becomes an insulator). Stay cool and you will find the fault. Good luck.

edit: You have hum? Where is it coming from? Again isolate. Hum is usually from improper grounding or pickup from proximity of power supply transformer or wiring.Is there any shielding
of signal wires, that is the short length of it going to the RCA connectors?

[cabsvrt]

Singa, thanks for the suggestions. I did move and jiggle cables while testing to make sure there wasn't a loose connection, and I looked for cold solder joints at both ends. So I moved on to the phono stage as the culprit.

Thinking back to when I received the VTL, I wasn't getting great sound out of my Dynacos (My Atma-Sphere amps were waiting for mods) and I needed to make sure that the VTL was working in case I needed to make an eBay claim. So I pressed my NAD THX amp from my sub in the home theater into service. It couldn't handle the load from the Martin Logans (1.5-2ohms I believe) and kept shutting down. So I used my Yamaha DSP-A1 that had pre-inputs and drove the ML's (when they were in the HT) before I got my Denon 5805.

Everything was fine until one night when I put a record on the Yamaha P-850, turned up the volume and got a squealing oscillation that shut down the amp. I assumed it was the Yamaha DSP-A1 but now quite obviously it was the VTL Phono. My buddy loaned me his Parasound behemoth amp and I didn't have a problem again until now with my homemade TT & arm combos.

I had an old phono preamp sitting around and plugged it into an aux input of the VTL pre and now I have stereo, not as good as the VTL phono stage... but working. I have come to the conclusion that there is something wrong with the tube phono stage. The left channel tubes are dimmer than the right, possibly making it more sensitive to what's plugged into it. I'm going to try some tube rolling today. I am keeping my fingers crossed that it's something simple.