Audio Horizons TP 2.0 Preamplifier

I can not seem to log on to the AH site. Has the address changed?
Joe

The site is still operating, but no mention yet of the new amp lines.

http://www.audio-horizons.com/

Tvad,
The power amplifiers are SETs. So far, an EL34 (~6 watts per channel) and an 845 (~25 watts per channel).

Has anyone who has had an early 2.0 model had to change out the four E88cc tubes yet? Mine are still original Siemens Cca and I don't have a clue how many hours I have on them. I'm curious what to listen for when the tubes are showing their age and need replaced. I'm trying to get the most out of my tubes because they are rare NOS and expensive.

I'm curious what to listen for when the tubes are showing their age and need replaced. I'm trying to get the most out of my tubes because they are rare NOS and expensive.
Sherod (Threads | Answers)

One indicator is buzz and/or hum that was not present before.

Another is loss of high end extension, but this is difficult to detect over the long term because it begins the moment the tubes are installed.

The best way to know is to test them with a tube tester. At the price of NOS CCa tubes, a tube tester like a B&K 606 is a small investment.