Audio Horizons TP 2.0 Preamplifier

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

Hi Michael,I can assist,simply e-mail me at lutesj@shaw.ca.

I strongly preferred the early 60;s Siemans cca's. But the cheaper Amprex White Label PQ's were also good, abit wetter and less controlled. Hiss level may vary with tubes. Unit should be very quiet, just a tiny bit with your ear right up to the tweeters.

hmmm...

I am having problems with the left channel popping and increased hiss on that side. I think there is a problem with this preamp. I reversed the tubes to see if it was them, and the problem stayed on the left, so I suspect there is a problem in the preamp somewhere...

This explains the higher hiss than I was expecting I think. It's really unfortunate because it sounds great when it's working fine, but I think this one has problems somewhere...

I'll talk to the seller and see what my options are.

---Michael