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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
tubegroover
2,279 posts
 
Peter I'm with Ian, your summary was great and I think the problem is narrowed down. Based on what you said I believe there is a tube problem somewhere, more than likely the inputs. You should be getting more bass than you are. This amp goes down to 2hz, almost dc into an 8 ohm load. The bass performance shouldn't even be an issue. With the pro-acs 8 ohm load you should note a big improvement in the bass with the zh270. Further I am really mystified by this glare you are hearing; poor bass, tube glare from the zh270, its gotta be a tube problem.

Try Brendan at tubeworld.com and just get the tubes recommended above, shouldn't be more than 175.00 or so to upgrade all 6. You'll want to do this down the road anyway, it is a great improvement and may just solve the problem. I really believe you have a tube mortality somewhere or a weak tube causing this anomaly. Try this FIRST and forget the wire for now. In the meantime see if you can locate a tube tester. I also don't believe the problem is with the Cary CD308. And keep up posted on the results.

When you get it right then you'll want to try those cryoed tubes for one of the best audio expenditures you'll ever make.
peter_s OP
1,088 posts
 
Tubegroover - would you go for the Cryo'd tubes first? Or do the NOS first? Thanks.
tubegroover
2,279 posts
 
Peter

I don't think the problem is with the output's, the 6jn6 tubes. Generally, a problem as you are describing is in the input/driver circuit, not the output circuit. I would try the inputs first, the tube complement recommended above.

So far as the cryoed 6jn6 output tubes go, try to get in touch with Allan Bghan at the e-mail link above and see if he even has a set of them on hand. I'm not sure that he does but he is talking about producing another batch, mucho inquiries. These tubes are all individually tested prior to the cryo treatment. So he is using the creme de le creme before the process. They are probably a lot better tubes to start with than Berning uses. Twl's point in his first post is a good one and true. The cryoed tubes are well worth it and you might want to just get both the inputs and outputs. If neither of these upgrades turn out to be the problem you still aren't throwing away your money, believe me. You can be assured that there is a system synergy problem but when you find it, your zh270 will be ready and waiting :)
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drubin
3,240 posts
 
Waitaminute!!! No offense tubegroover, but he just bought a brand new, highly-respected and expensive amplifier, and now we're saying he has to upgrade the tubes in order to get even acceptable performance from it? Does this mean Berning sells a $4500 amp that basically sucks unless you do aftermarket upgrades? He should send the friggin' amp back to David Berning and have it checked out, or get his money back. The thing should be damn good as it is. Later on, he can look into extracting higher levels of performance with tube changes and the like.
tubegroover
2,279 posts
 
Dan, maybe I didn't make my point clear enough. If there is a bad tube Berning should and will replace it. If one were to be conservative and not spend the money, the tubes should first be tested with a tube tester as noted above. I really believe the most ill advised thing to do at this point is to replace cables and cd players. Peter has 2 cd players and several sets of cables on hand and he is getting the same results. Process of elimination and common denominator leads to the prime suspect being the amp. Since David Berning's products have a legendary track record of reliability, my guess, based on the symptoms, is that there is a tube problem.

You are absolutely right, he should get acceptable performance from the amp stock. The problem is that he isn't so where does the problem lay? That hasn't been detemined yet. My recommendation is on the premise that there is a tube problem but this is not certain. Is the dealer readily available? How much would it cost to ship back to Berning to have him check it out? I am speaking of a 300.00-350.00 total expenditure for NOS and cryoed treated tubes that will improve the performance of the amp in the long run regardless of what the problem is now. If Peter's resources are limited I would recommend first getting the tubes tested to see if that is where the smoking gun is holing up.
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