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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

Showing 4 responses by twl

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.
twl
3,251 posts
 
You need to get some NOS tubes. I have a MicroZOTL and I had the same problem with tube glare. The manufacturers cannot use NOS tubes in a production unit, because there is no guarantee of availability of the right tubes at any given time, and the price fluctuates too much.

Talk to A'gon member Tubegroover. He has a 270 and has some experience with NOS in it.

When I put Mullard 12AT7's and Sylvania 6SN7's in my MicroZOTL the glare was gone and overall sound and detail was much improved.

For the best bass control, use the Normal Feedback setting. It provides the lowest output impedance for best bass.

And trying different cables is a good idea, because, as we all know, cables are very synergy dependent on the amp and other components. When you change an amp, it is likely that cable changes may be in order also.

It is my opinion that the NOS tubes will give the improvements that you want. I know that it is a bitch to have to get NOS tubes when you have just bought a new amp, but that's the name of the game. I have come to expect to have to do that. They just can't put them into the amp for the reasons I described above. There is a limited supply of NOS and they are getting rarer, and more expensive, and eventually they will dry up altogether.
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.
twl
3,251 posts
 
Ken, I am doing just that. I have a pair of Lowther EX3's in modified Voigt Pipes(100db), and I have a special order cutom amp coming from David Berning. It will be a battery powered, choke-loaded, SET ZOTL, with type 45 output tubes, and 2 watts nominal. I will be using the Emission Labs VV45 Mesh-Plate tubes. It will be loosely patterned after the Siegfried, but with the obvious differences of battery power, and choke-loading, and of course the type 45 tubes. Some people I've talked to are calling it the "Holy Grail" of amp designs. Probably pretty close.
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