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Problems getting the best out of my Berning

Hello fellow Agoners,

I beckon for help from experienced users of the Berning ZH270! I just received mine new a week ago, and although it is an incredible amp, it is not meeting my expectations. HELP!

First the good news:

This is the fastest amp I have ever head, and it has virtually no noise floor. I am truly impressed with these aspects. It handles most everything with ease and clarity.

Now my system:

Proac 2.5 loudspeakers
Cary CD308 and Arcam FMJ CD23
Kimber PBJ Interconnnects
Audioquest Type 4 cables

(I've also used Dynaudio Audience 72's and all MIT cables, and Triangle Titus + Audioquest Slate cables and PBJ IC's).

OK - now to the problem:

On all three setups mentioned above, the amp seems strongly biased towards the midrange and upper midrange, resulting in a fatiguing presention. There is a significant decrease in bass (not detail, but the actual movement of air) from the other amps I have used for comparison (Classe CAP 101, Pass Aleph 3, Adcom GFA 5400). While the detail and fastness are truly amazing, the midrange emphasis is getting the worst of me!

I've spoken with David Berning and Frank S (FS Audio.com) and both encourage some tweaking to get rid of this perceived (psycho?) acoustic bias. Frank is going to send me some interconnects to try. David mentioned that others have changed the tubes. He doubts anything is wrong with the amp.

Is this all in my head, or have others had similar problems and needed to make adjustments to get it right? While all my other amps are currently SS, I have trouble believing that this is the "tube sound" (I've heard other tube amps). Other threads mention system tweaking to get rid of a "glare" with the ZH270, changing tubes, sensitivity to cabling. My perception of the sound is pretty strong - currently I like my Aleph 3 a whole lot more with the existing setup.

I'm willing to put some time and money into making this work - because in all other respects, this is an absolutely amazing amp. Perhaps it doesn't suit my ear - but I want the advantages of this amp without the disadvantages I just mentioned. Please - suggestions on what to do from all you experienced Berning fans... so many high commendations cannot be that far off (right?).
peter_s
twl
3,251 posts
 
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.
phild
603 posts
 
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.
tubegroover
2,320 posts
 
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).
tubegroover
2,320 posts
 
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.
twl
3,251 posts
 
Hey Tubegroover, Nice Tubes! I just thought that I would pass along my "glare" info. I don't have a 270, so I was sort of just "extrapolating" the PP Microzotl circuit to the PP zh270 circuit. However, I did get a much better midrange smoothness when I got rid of the JAN Phillips 12AT7. So I thought that might help in this case. Of course, 1950's Brimar Black plates would be even better than my Mullard 6201's.
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