Tubes Asylum: REVIEW: David Berning zh-270 Amplifier (Tube) by az

Model:	zh-270
Category:	Amplifier (Tube)
Suggested Retail Price:	$4500
Description:	see the web page
Manufacturer URL:	David Berning
Manufacturer URL:	David Berning

Review by az ( A ) on October 23, 2002 at 05:22:31
IP Address: 158.166.10.72

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for the zh-270

please note, this is just a description of how this amp sounds in my system. your mileage in your own systems may vary. i don't understand how its works: for technical explanations find the berning web site.
i've compared this amp to both my previous very well reviewed solid state mosfet uk amp which uses a switch mode power supply, and a valve amp i had using kt88 in the output stage working into output transformers.
put quickly it identifies the weaknesses of the otheramps quite clearly.
it makes the solid state amp sound slightly crude and harsh. what appeared to be resolution and dynamism somehow no longer appear to be that. the berning gives as much if not more energy, but provides more detail and information without sounding sharp.
it makes the valve amp sound slightly rounded and comfortable. what appeared to be sweetness and presence seem now to be a slight lack of precision perhaps fuzziness.
overall, the berning combines unusual characteristics, at least for me:
very convincing solid precise soundstage, a great deal of detail without any agression or sharpness, dynamism and subtlety. perhaps the most surprising attribute is the bass: very quick, dynamic, but subtle and informative at the same time. it makes the solid state amp sound like someone thumping a door.
one point to remember: the amp has three feedback settings. all of the above comments are based on the maximum feedback setting. the amp can sound sweeter still: in fact i'm enjoying more and more the medium feedback setting. the low feedback setting sounds pretty relaxed in my system but is still surprisingly alive.
i have changed the valves for the 'input' stages to NOS. This resulted in small but worthwhile improvements. Slightly more precision, more of a pinpoint focus.
incidentally, the berning has also been tried out in a friends system which includes mbl 101 speakers. it was only a short try out under suboptimal conditions, more to come on this, but first impressions were very good. it gave a lot of precise low frequency energy and information listening to a mapleshade percussion recording (asante if i remember correctly). it coped with the speakers without any difficulties. perhaps this should not be a surprise. the dick olsher review on enjoythemusic describes how the amp manages to drive the big soundlab a1s quite well. for me, one unexpected result of the session with the mbl 101s was that even on the medium feedback setting where the output impedance is around 3 ohms, the bass still sounded really under control.
the comments above aren't meant to imply its the perfect amp. its just that given my listening experience that's how it seems.
although i'm part of the cd generation, given the improvements with the berning, i'm actually thinking of getting a turntable. it could be even more impressive. any experiences with electrostatics/otl type amps and listening profile similar to mine?

Product Weakness: in the context of my system: clear, lively, subtle, dynamic, transparent, informative, 'natural'?
Product Strengths: in the context of my system: none i'm conscious of, i have the impression the cd may now be the limited factor.

Associated Equipment for this Review:
Amplifier:	as in review
Preamplifier (or None if Integrated):	audiosynthesis pro passion: dual mono attenuator, shallco mechanism, vishay bulk metal foil resistors
Sources (CDP/Turntable):	meridian 506-20 heavily modified: output transistors, clock circuit, voltage regulators, capacitors
Speakers:	audiostatic dci plus (now called wing)
Cables/Interconnects:	audiosynthesis silver hard wired to attenuator, goertz speaker cable
Music Used (Genre/Selections):	mostly classical, some folk, acoustic, and jazz
Room Size (LxWxH):	18 x 27 x 8
Room Comments/Treatments:	experimenting all the time
Time Period/Length of Audition:	enough
Other (Power Conditioner etc.):	some kimber power cords
Type of Audition/Review:	Product Owner

Product Weakness:	in the context of my system: clear, lively, subtle, dynamic, transparent, informative, 'natural'?
Product Strengths:	in the context of my system: none i'm conscious of, i have the impression the cd may now be the limited factor.