Audio Horizons TP 2.0 Preamplifier

I had I think a similar issue with my 2.1 and it turned out to be tube microphonics. Using Herbies tube dampers eliminated it by dulled the sound, floating the circuit board helped a bit, also you can try very gently bending the pins out just a bit on the offending tube to get a tighter connection. You can tell which tube is trouble by pulling off the top and while the unit is powered up and connected to speakers, gently tapping the tubes with a pencil eraser. You will hear if one tube is particularly microphonic.
The best solution however that I found that completely eliminated all noise and made the unit totally silent was to replace the tubes with other 6922's. I found Seimens 1960's cca's to be amazing in the unit, but also cheaper Amperex PQ's etc provide wonderful sound. Don't give up- it is a wonderful preamp and this should be able to be fixed easily. You can also talk to Victor or Joseph at AH and they will do everything in their power to help you.

Thank you very much for your help. I thought it was a tube, but best to ask. When music is playing it sounds remarkable, it sounds like everything I hoped my stereo would one day be.

One last question, the unit I have purchased has the remote on/off, do you turn it off completely on the chassis or use the remote? My AI standby always had limited current going to the tubes to ease start up.

Thank you again.

Thank you for your help. Much appreciated!

Folks, I just purchased a AH 2.1nbr preamp and have a few questions about it...

It has basic EH tubes in it, and I would like to upgrade those to a better quality tube. Any recommendations for a first roll? I'd prefer to no be purchasing $200/tube valves for this. Maybe some mullards? Actually, this thread is so large that I know that there has been some discussion about what the various tubes impart to the sound; I'm wondering if there is a good summary somewhwere.

I think someone long the way may have made a mod or two... the fuse housing to the right of the IEC outlet is not hooked up. I'd prefer to have some protection for the preamp to keep it from burning up if there is a problem. There is a fuse on the board nearest to the IES socket, but I am speculating that it is a secondary fuse. Can someone provide me with a photo or two showing how the input power fuse is supposed to be hooked up? I'll get it wired up from there.

The main ON/OFF switch on the preamp was damaged in shipping, and I need to replace it. Joseph says it'll be $25, but he is out of the country for the next month. Does anyone know exactly what the switch part number (manufacturer, etc.) is? If it's nothing special, I'll find it from another supplier and wire that up as well. Id rather not wait for Joseph to return, although I am able to get the switch to work (for now, not sure for how long, though).

Lastly, there is a bit more hiss with the preamp in the system than I had expected based on comments I have seen, so I'm wondering if this is somewhat dependant on the tubes? I don't believe the hiss is volume dependant, but it does change as the preamp goes through it's warmup. It's currently hooked up via RCA, but I'll eventually get a balanced-capable amp, which hopefully will reduce this effect if nothing else will.

Thanks,

---Michael