Problems getting the best out of my Berning

Hi Peter

Initially I would be tempted to agree with Dan but there shouldn't be an impedance mismatch with the Berning/Pro-ac's. It must be elsewhere in your system or set-up. There is another proac/Berning user (Ian where are you?) that loves this combo. Obviously (at least to me) there is something wrong here beyond what you expected. There should be NO tube glare unless there is an interface problem with wire, certainly not from the amp unless you have a bad tube(s) which is possible, but somehow I doubt it, Berning is too meticulous to send out a new product with such a defect. Upgrading tubes will enhance performance but that is not the answer for tube glare with the zh270, break-in possibly.

An emphasis on the midrange is something more puzzling and I have no answer off the top of my head because I don't hear this in my system and never have nor have I heard it with other speakers and the zh270. I would agree that the bass through the Berning won't offer the slam of other ss amps but it should't be a problem, to the contrary. Bass should balance well with the mids and highs. This amp is all about superb tonal balance along with that clarity. You don't mention high frequency performance at all which with the right speakers and wire should be top shelf. So now all that is left is to troubleshoot.

Have you tried the 3 feedback settings. Do you note any changes between them.

What is the amp sitting on, how close to the digital source. The amp uses ultra high frequency so there could be a possible problem with the location of the amp that may be contributing to what you are hearing.

As Dan asked, are you running directly from your digital source to the amp or do you use a pre.

Certainly the MIT's in general are forgiving cables and shouldn't present a problem at all. The fact that you have tried so many different cable configurations leads me to believe that this isn't the foundation of the problem either but still...it wouldn't hurt to try something else, maybe Cardas. I am using Luminous Tech Syn Sig cables with superb results.

Lastly it could be a break-in of the amp. I wouldn't completely eliminate this. I have heard it first hand and it can never be ruled out. The bottom line is the Berning with the pro-acs should be singing in your system and you shouldn't be hearing any of what you are describing. Please keep us updated. I am confident you will find the problem so hang in there.

If your ZH270 currently has the JAN Phillips 12AT7 tubes in it, I would try to change them to NOS Mullard 6201 Gold Pins($35 each from Upscale Audio). In my MicroZOTL these JAN Phillips 12AT7's were the primary cause of the tube glare. I just looked up the ZH270 tube complement on the website, and found that indeed it does use 12AT7's, as I suspected, because Dave likes to use the 12AT7. When I did this with my MicroZOTL, the tube glare was gone. Substituting Sylvania GTA for the stock Sovtek 6SN7's made an improvement in detail and bass. But I feel in your case, the offender is likely to be the JAN Phillips 12AT7's.

Hi Peter...I'm not saying that there is some sort of mismatch going on with your components or cabling (it sounds like there is), but I did want to point out that the Berning amps are an OTL amp...not a standard tube amp. OTL amps don't have a standard tube amp sound.

It might be worth checking into other interconnects and cabling. I haven't used Kimber PBJ for years, but I always found them to favor the upper frequencies. I never used them for my primary sources. I'm not familiar with the Audioquest.

Twl

I have never had a glare problem with the Berning. Actually it is only the second tube product I've ever owned that didn't have this problem which was usually fixed with rings and better tubes but never completely eliminated, especially the high frequencies which is damn annoying trying to correct. The Transcendent OTL was the only other tube amp that didn't do the ringing/glare thing. I also had this problem with several pre-amps as well. I suppose it can't be ruled out. I would be more inclined towards a bad tube being the culprit rather than the absolute quality of the tubes being used. The tubes are operated very conservatively in this circuit so while better tubes will yield increased performance a bad tube would present very audible problems. Peter if you have access to a tube tester, check out the tubes to see how they measure. Maybe you have a short in one or more.

If all else fails, I will recommend the following tube compliment I use 12AT7's Brimar Black Plates NOS 1950's, 5965's GE "5 Star" NOS Platinum 1% pair 1970's for the input/drivers and you may want to get in touch with Allan Bhagan @ info@allanbhagan.info for the cryogenically treated 6jn6 outputs. These tubes especially made a dramatic increase in performance, like a component upgrade. I still think you have a problem elsewhere, including the aforementioned bad tube (s).

Hi Phild

The Berning doesn't have a standard tube amp sound to be sure but it could never be mistaken for a ss amp. It has the soul of an SET with resolution of low level harmonic detail across the frequency spectrum. It is as airy and resolving of spacial information as any amp I've ever heard, period. Of course I can imagine it not sounding this way if everything else is not right in a given system.

The reason it sounds different from most other transformer coupled tube amps is simply that it is faster which is the OTL sound that you speak of, they all seem faster and more resolving. There is definitely a problem with Peter's system/amp that will be worked out, of that I am certain.