Pre-amp causing loud hiss from speakers


I have a BAT VK3i with Quicksilver Horn mono-blocks and Klipsch LaScala's. This setup is dead quiet, however when I recently hooked up Rogue Audio M-180 mono-blocks there was a loud hiss coming from the speakers well past the listening spot. This noise was constant even with the volume down to zero and occurred with either balanced or rca connectors.

When I took the BAT out of the equation there was now only a faint hiss coming from speakers but one had to put your ear to it to hear it. After disconnecting all components from the BAT and putting it back in - the noise returns. I tried a Conrad Johnson Classic and there was no noise.

So does anyone have any ideas as to why the BAK and Rogue Audios amps do not play nice together?

Thanks
deadlift
You shouldn't have a problem. I assume you are using your Rogues balanced. What kind of IC's do you have? You need to make sure they are internally balanced, and not SE with XLR connectors. Also, make sure you try both sets of binding posts on your amps. Pick the ones that sound best.
Your Rogue amps input sensitivity is 1V (high sensitivity). Your QS input sensitivity is 9V (very low). What this means is that the gain (and it's tube noise) from your pre-amp's tube section will be magnified substantially more with the Rogue and, especially when driving highly efficient speakers such as yours, will result in noise. This is not controllable by using your pre-amps volume control as it is in the circuit before the tube section which is always seen by the amp at it's full output gain.

Your problem could be that the tubes in your pre-amp are not 'low noise' enough for the Rogue Amp when it is amplifying your high efficiency speakers. If low noise tubes are not the problem and you still want to use your pre-amp with this amp/speaker combo you can try using in-line attenuators at the amp inputs to reduce the gain from your pre-amp. This may be inelegant but there is not much down side - it is nothing much more that a fixed value resistor in this kind of attenuator.

Hope that helps a bit.
I purchased a used BAT VK-300SE which had the same problem upon arrival.
I decided to work with the seller and had to return the unit to BAT.
It was fixed and worked flawlessly thereafter.
BAT said it had a bad "voltage regulator".
BAT graciously fixed it under warranty even after we explained that I was the new owner.
Like the late-great HP used to say: "If it works the first time, it's not high end"...
As Newbee correctly points out the gain architecture of the system is completely wrong for the extremely high sensitivity LaScalas, which will magnify any noise upstream.

For what it's worth, IMHO the Quicksilvers are much better sounding amps than the big Rogues and will have much lower operating costs as well. Add to that the lower gain which is correct in the context of your system and it may be time to move the Rogues on.
I will experiment more with the IC's and binding posts, but I fear as noted the gain architecture is way off - oh well part of the journey. I do wonder if it's not inappropriate here to ask what a set of Rogues would be worth with less than 30 minutes run time?

Thanks
Since you're in for a penny you might as well check one more thing. With the amp off, remove the interconnects from the amp. Replace them with, preferably, shorting plugs, but RCA caps would probably work as well. Turn the amp back on. What you are now hearing is the internal noise from the amp alone.

If the noise is not too bad you may be able to use line level attenuators such as those available from Parts Express between the preamp and amp and this will solve the problem without heroic efforts as Newbee suggested.

The other possibility is to call Rogue, they are most helpful and may be able to internally alter the gain of the amp.

Finally, Rogue is a hot brand and I would start at 20% off retail and probably be ready to accept 30% off retail. Just a guess here.
I will give it a shot nothing to lose. Those attenuators are RCA would using balanced attenuators make any really difference?

thanks again
I can't think of any reason that the balanced attenuators would sound better, or even different. What will make a difference though is the amount of attenuation that they will provide. 10db attenuators are common (and the ones that I have used) but that might not be enough. You can also get them in 20db and perhaps anything in between. FWIW Rothwell makes a nice in-line attenuator. If the hiss is really loud I'd try the 20db ones first.
can't you just proceed with unhappy return after half-hour of listening?
"05-27-15: Deadlift
I will experiment more with the IC's and binding posts,"

Just list your IC's. Someone here will know if they are balanced or not.

"05-27-15: Czarivey
can't you just proceed with unhappy return after half-hour of listening?"

I agree. Any good dealer will try to do something for you.
The interconnects are from Transparent Audio probably about 10 years old. I really want to try to make this work before heading back to the dealer.
There is a benefit from getting all one's components from the same manufacturer....they play together well.
Well, I guess your run of the mill, 10 year old Transparent cables are probably internally balanced. Try new amps first and if they don't work out, you can always revisit the cable issue.
I suppose I could use the Conrad Johnson with the Rogue's as for whatever reason that combo producing no noise and leave the BAT's with the Quicksilvers and go back and forth as I wish....
Interestingly the output gain of the CJ is either 22 or 27 depending on where you look (different models?) and the BAT is 20. This suggests to me that the BAT output stage is just inherently noisier than the CJ or that the tubes you are using have not been screened for noise, i.e. 'low noise'. Maybe both.

BTW, FWIW, cabling, wires, cords, connectors., etc can have an effect on tone and clarity, but they do not create or reduce 'hiss'. If you really like the BAT's sound more than the CJ, and that's apparently the current issue, just focus on the gain issue, i.e. tubes and/or attenuator. But if the CJ is just as good to your ears when combined with the Rogue, just use it, and put the BAT in the closet until your change your mind. :-)
That's what I noticed as well, I thought the situation would get worse with the CJ not better. I did re-tube the BAT awhile back I will detail the tubes I put in tomorrow - perhaps there are better tube choices.
"BTW, FWIW, cabling, wires, cords, connectors., etc can have an effect on tone and clarity, but they do not create or reduce 'hiss'."

Yes they can and I can show you any time on my own system. Any time you start fooling with balanced and SE components and cables you can make a mistake and end up with a noise.
Interestingly, the cj Classic is not a tube preamp, but a tube/solid state (FET) hybrid, which may speak to the lack of noise in the piece.
I agree Viridian. Tube electronics today used more to please the child inside adult.
Veridan, Excellent observation, I missed that.

Zd542, I realize that there can be line noise on single ended connections that may be eliminated using a balanced
system and cable, especially in long runs. But this conversation was not about line noise, it was about 'hiss' originating in the pre-amp which is going to persist when passed on to the amp without change because of cabling and/or connectors. That is my experience. Your comments, without specificity anyway, baffle me, but I'm open to hearing about your experience when you encountered this issue in the past. And the techie stuff to explain it if you are aware. Thanks.............Perhaps we can all learn something.
"This noise was constant even with the volume down to zero and occurred with either balanced or rca connectors."

The OP referred to the problem as a constant noise in the above quote. To me, that sounds like the problem may be something other than a hiss. Sometimes these type of problems are hard to explain in words, and that's why I recommended the OP check his cables.

"That is my experience. Your comments, without specificity anyway, baffle me, but I'm open to hearing about your experience when you encountered this issue in the past. And the techie stuff to explain it if you are aware. Thanks.............Perhaps we can all learn something."

Heres a specific example of a noise caused by improper cable selection in one of my systems. I have an Ayre V-5 which is balanced and a CJ Premiere 18 preamp that is SE. Sometimes I put the CJ in the system with the Ayre. If I use SE cables, I get a constant noise. When I use balanced cable, I don't get a noise. Just to be clear, the sound is a noise, not a hiss.

In my other system, I have a pair of Wilson's that are pretty efficient (94 is I remember correctly). I use a Wadia CD player going directly to the amp. In this system, I can get a hiss related to too much gain using the factory setting on my Wadia. In order to get rid of it, I need to go inside and lower the global gain with the dip switches Wadia puts there just for this purpose.

And that's it. Either way, noise or hiss, its just something I need to be aware of and know how to deal with it. As far as the techie stuff as to why this happens, I really don't know. I'm able to fix the problem and that's my main concern.
Just some updates - the balanced cables I was using were Transparent Audio Balanced Musiclink plus. As for the tubes in the BAT they were purchased from Upscale Audio - 4 Electro-harmonix 6922 and 2 Pope 6V6GT.

I will spend some more time this weekend checking cables etc.
I checked on your IC's. They're fully balanced cables, so there's no need to go further with any checking. Unfortunately, it looks like your fix will be one of the more expensive solutions that some of the others have suggested. But I would still keep experimenting and definitely get in touch with your Rogue dealer. The longer you wait, the more permanent the sale will most likely become.
Wanted to add an update to this: I found a Brent Jesse on these forums and contacted him, he felt it could very well be the 6922's in the BAT causing the issue. I purchased four tubes from him, checked just to make sure the issue had not resolved itself and then swapped in his tubes. Now only dead silence with either balanced or RCA connectors - life is good.

I did add some of those attenuators as well which are working very well. So thanks to all for your help and support.
Deadlift, the same thing happened o me. Bought a used pre-amp that came with 2 sets of tubes. Turns out both sets were noisy and I thought it was the pre-amp. After purchasing a new set of tubes, I was very happy to find that the issue was the tubes, although I paid a premium price because of the value of the supposedly good tubes. My loss.
Just about two hours ago I put another new set in and they are dead quiet too. Happiness in tubeland. :)