Audio Horizons TP 2.0 Preamplifier

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Hi all;

I'm rather new to tube equipment and high-end in general. This problem deals with the tubes on our TP 2.0n preamp.

The other night when listening, I noticed an unusual noise coming from the left speaker. We had just shaken the room with Micky Hart's Dafos album... serious bass on The Beam.

The noise was a cyclical, tinny, almost motor-like sound that would repeat in a 1-2-3 pattern. It was very noticeable from the listening position - enough to interrupt the session. Interestingly, it had the same tone or pitch as the microphonics that I *sometimes* hear on the pre-amp... if I tap the volume knob, I get that ringing sound. I turned off the TP 2.0 for a minute or two, re-started, and the sound was no longer there.

Just for gits and shiggles, I later rolled the tubes over one position. 1 went to position 2, 2 to 3, ..., 4 to position 1. I ensured that they were well seated, and then reinstalled Herbie's Tube Dampers a bit higher up - about as high up the tube as I could get them.

When I went to play again, at idle the preamp was dead silent. No microphonics - which continues to be the case - no recurrence of the cyclical noise.

So, the questions are: What's going on with the tubes? What might I have done to correct the problem - was it reseating, or repositioning? Do I have a tube going bad? If a bad tube were in, say, position 1 and then moved to position 2, am I going to be missing or risking something?

The tubes in question are Amperex PQ white label 6922s.

Thanks! I have no doubt that someone knows what's going on here.

Rob

Hi Rob,

This was a fairly common problem with all my tube preamps of the past.

You could try cleaning all the tube pins with Caig, if it still persists, you may have a slightly finicky/faulty tube that might need replacing.

I'm sure the ceramic tube sockets are OK, they're high quality and grip like a vice.

Thanks, Rx8man...

One question that I still have: What are positions 1 & 3 used for, and what do positions 2 & 4 do on the TP 2.0?

Rob

Rob,
Perhaps Joseph or Victor can answer your question best. All they told me, back when I was tube-rolling, was that locations 1 & 3 were the most critical for the sound. I would imagine that these are in the signal path. As to what locations 2 & 4 do, I can only take a layman's guess that they are for regulation. It's best to ask the "Master"( J. Chow) himself.

I'm new to AH, now trying out a modded 2.0 before ordering a 2.1. I've talked to Joe quite a bit and to answer about the tubes, 1 and 3 amplify, 2 and 4 are buffers. I love the preamp and after 2 days have already decided to order a new one and this is after living with an $8500 CJ 16LS II for over 3 years. Thanks to Grannyring for the recommendation. The demo doesn't work with my Atma-Sphere amps in balanced mode but even through the RCAs it's obviously a great preamp. I can't wait to hear the 2.1 in balanced mode as I'm sure it will be an improvement. This is the first thread my lazy ass has ever bothered to reply but this product is worth it.