Frustrated with new pre-amp and need advice

Hello all. I just bought a new tube preamp from a well-respected company. I'd rather not say who at this point because I'm still trying to work with them. But I am not real satisfied with the responses I've gotten thus far and need to know if my concerns are valid.

There are two main problems: (1) whenever I change sources or go passed 0 volume, I get a loud thump through my speakers. (2) When I have the phono input selected and i'm listening to an lp (via the internal phono board) but my cd is spinning too, I can clearly hear the CD source. It's intruding into the phono input.

So the manuf. rep has pretty much blamed problem #1 on either my ground connection or my power amp. However, when I use another pre amp (a peachtree decco), this problem doesn't happen. So how can it be a problem with my ground or amp?

For problem #2, they've not commented on what could be going on, and their silence doesn't make me feel warm and fuzzy.

So I'd most like to know if others ever have similar problems with any of their gear, if they indicate a defect in the equipment, or are these issues things I'll have to learn to live with.

I appreciate all comments!

I assume the tube preamp you are speaking of is a tube unit? To me is sounds like one of two issues. 1. The preamp is faulty. 2. Some tube preamps and solid state power amps simply don't get along. If the preamp is under warranty, why not ask them to replace the unit? Then again what if they do and that doesn't solve the problem. You're right back at square one again. I have had a couple of friends that have has a popping noises in their preamps but they never mentioned the crosstalk. In a properly designed preamp you should not hear the crosstalk. It will be interesting to see what they do and what solves the problem.
I had a problem with my Cary preamp when I first got it, and I got just the opposite response. The dealer put me on the phone with Dennis Had of Cary, he listened through the phone, apologized, told me to pack it up and ship it back. I had it back the next week. Something was just miswired, it happens, and they fixed it and sent it back.

I would give the preamp back to the dealer.
Let me first say, that there's a good chance I'm not reading what you posted correctly.
It's been my experience that it's always a good practice to lower the volume to zero before switching sources and turning off the unused sources.
Unsound you are correct, that is what we were taught but you don't have to go down to 0. Go just low enough that if your preamp generaes a popping noise or pulse surge it won't send through your amp. This usually does not happen in tube amps. If your gear is designed properly, grounded properly and better than good quality components are used you should neer hear crosstalk or have any popping noises, etc. Oh, and a good power supply should be included on the list too.
Sounds a lot like this thread:

If it's same manufacturer I'd tread carefully.
Were I in your shoes, I would return the item for either a replacement unit or a full refund with preference toward the refund. Unless the unit is faulty, your use of an alternate pre proves there is something about the unit in question that makes it incompatible with your existing equipment. Good luck.

If the co. has a very consumer friendly stance, asking and getting a replacement unit this early on ought not to be an issue. Even if it’s mentioned some more run in time is required first.

A second same unit will do one of 3 things… alieviate the issue entirely, or determine it is a mismatch for your current setup or lastly, some revision is necessary to the current production models.

Each of those items ultimately formulates into a win win situation.

I don’t use all the inputs on my tube preamp. It has 4 pairs/sets. It is SE only. Normally I’ll use two. A while back after reconfiguring sources on the preamps inputs I mis-selected one of them. I forget exactly which one the selector knob was set to, and while in the other room used the remote to raise the vol. Both sources were on at the time too.

I kept raising the volume and could only faintly hear any source material. Turned out the knob was on a blank spot and the source I heard was on the adjacent or next position over.

So indeed there was some bleed through that could barely be heard yet the volume level to encounter this anomoly had to be at near the max setting.

Once previously on a 100% balanced preamp this exact same thing occurred. In both cases I feel I was very lucky.

During normal operating levels, all other sources were/are inaudible. Again, only when at the near full on vol level or at full on was anything at all audible from an adjacent source selected position… so we’re talking extremes here.

Not just run of the mill routine operating procedures.

I’ve had several preamps and amp combos in here… with some being quite inexpensive and some being very expensive. In none of those mixings have I ever had any bleed thru from one source to another aside from my above accounts.

Lastly… a brand new preamp… SS or tube… should not induce any thunks or plunks audibly to the speakers when sources are changed, especially if prudence with the volume is in force during the source changes… or at least I’ve never experienced such things with any pre or even proc I’ve yet owned..

Hopefully your brand will see to it you are treated fairly and satisfied very soon.
Proper cable dressing can go a long way in detering alternate signal pick up. Though actually being able to do it can sometimes be an excercise in futility. :-)
somehow your preamp seems to me mis-manufactured in the sense of correct values of bias supply. if the tubes are over- or under- driven that would seem to show your case. Audio Research had done some mis-manufactured units and fixed them at no even shipping cost with no questions asked from anybody. The fix was to change input(grid) resistor values from 1K to 10k. or vise versa(don't remember precisely).
I am the OP in the thread that Aggielaw references above. Note that the issues this poster is experiencing are different. The POP I have with the Nagra unit is only when it is first powered on, NOT when I switch sources subsequently. There is also no bleeding from one channel to the next. I have also subsequently learned through correspondance with several real experts around the country)that many tube preamps ( will exhibit this characteristic (a pop) when first powered on, and it is not necessarily something wrong with the pre. But it does require you to always power on your amps AFTER the pre has been powered on. Which, as an aside, is a royal pain for me. Anyway, my point here is that I think that Slanski is experiencing different, and potentially more problemmatic issues with his pre.
A bump when changing sources could be a poorly designed or miswired source selector switch.
Bleedthrough is avoidable, if the manufacturer shields the input wiring and uses a high quality source switch with low crosstalk.
Some preamps go to the extreme of shorting unused inputs, so that there is zero, nada bleedthrough.

It seems that your preamp has design or wiring issues. I suggest an exchange or return, unless it is a 200 dollar unit...then those problems are to be expected.
Which for example $200 unit?
Usually they do not have these issues.