the NEW Zana Deux, ZDT and Balancing Act thread

[oatmeal769]

So, I'll start.

What's the deal with the 4 pin connection, and slew rates being improved? Is it by virtue simply of the 4-wire connection, or is it a byproduct of having the two transformers as well?

Does it have the same virtues of a balanced setup as far as greater separation and less crosstalk? Please feel free to wax on to a non technical type, I'm here to learn.

Do I need to consider a ZDT rather than a ZD if I have no plans to run speakers off the amp?

[tkam]

The 4-pin is likely for K1000s and/or balanced phones. Headroom kinda made the 2 x 3-pin xlr's standard for balanced phones but many people prefer the single 4pin xlr for that.

[Sherwood]

The ZDT, by simple virtue of having a transformer, will sound very different than the ZD. It should, if I'm not mistaken, have a "tubier" sound, since the primary explanation I've heard for the good tube sound is an output transformer.

Also keep in mind that having speaker-level outs is useful for more than just speakers. Stax transformer boxes run off speaker outputs, and are (in my experience) an excellent way to listen to Stax headphones for a lot less than a dedicated amp.

And I much prefer the 4 pin balanced connection. Makes more sense to me.

[jp11801]

if you want a plain ZD I think youll need to go used

[jp11801]

The ZDT, by simple virtue of having a transformer, will sound very different than the ZD. It should, if I'm not mistaken, have a "tubier" sound, since the primary explanation I've heard for the good tube sound is an output transformer.

The ZDT sounded more controlled and linear to me than the ZD did but both are examples of non mushy/bloomy tube amps.

[Icarium]

Yeah the ZDT does not sound "tubier" imo. It's very musical but its also extremely precise and detailed.

[tkam]

Yeah for some reason transformers get a bad rap, but good transformers sound a hell of a lot better than most things.

[Sherwood]

I imagine they get a bad rap because they're associated with a time when amps were poorly designed, and could not function without them. The OTL amp was a revelation, or so I'm told.

[dsavitsk]

It should, if I'm not mistaken, have a "tubier" sound, since the primary explanation I've heard for the good tube sound is an output transformer.

The primary reason for good tube sound is that tubes are very linear devices.

Transformers are useful things, and when correctly designed and implemented, will do little damage to the signal.

Yeah for some reason transformers get a bad rap, but good transformers sound a hell of a lot better than most things.

Transformers get a bad rap because good ones tend to be expensive.

I imagine they get a bad rap because they're associated with a time when amps were poorly designed, and could not function without them.

You have your decades wrong. The poor designs are from the 50's. Transformers were, by then, old hat.

The OTL amp was a revelation, or so I'm told.

Oh my.

[Sherwood]

Really? Am I that off? I read this huge article about George Kaye, and how he and his mentor pioneered the OTL amp, and how it turned the amp world on its head. I freely confess my ignorance on the history of tube design. I probably should have shut up already.

That's the last time I take Stereophile at face value. I suspect you've all come to the same conclusion, but I'm the trusting sort.

[deepak]

If a chicken is a cow, and why wouldn't it be, then chicken wings taste like steak

[Sherwood]

[Sherwood]

...

[Sherwood]

[dsavitsk]

Lots of things have turned the amp world on its head. Feedback, transistors, Class B, Class D, etc. Maybe OTL is among them. That doesn't mean that these things lasted, or that the long term evaluation is necessarilly good. It also doesn't mean that they are bad. I am sure there are plenty of wonderful OTL amps out there (well, I'm not actually sure of that, but for the sake of argument I'll stipulate to it), but OTL is too generic of a description to necessarilly mean much. There are certainly bad ones too.

Me, I often use transformers as I find the designs I make with them to be both intellectually interesting, and good sounding. But, you'll find that others disagree.

[Donald North]

I'll take a GOOD transformer any day over a capacitor.

As for transistors...

[TheSloth]

Slightly off topic, but I've always wanted to understand a bit more about this tube v. transistor argument.

I understand that there are lots of sonic preferences involved, but from a purely technical perspective, is it possible to design/produce a pure tube amp that can measure as well as a state of the art solid state job in terms of output power/harmonic distortion/damping factor/FR linearity/anything else you can throw at it?

I'm not trying to say those measurements necessarily 'mean' anything in the overall sound, I'd just like to know some of the 'science' behind the arguments. I have some dumb conception that I've picked up that somehow a good SS amp is more 'accurate' to the original source signal, and would like to know if there is actually any technical basis to that statement whatsoever, at least comparing best case scenario to best case scenario.

[dsavitsk]

It's a big topic. These are probably as good as anywhere to get started:

[url=http://www.sixmoons.com/industryfeatures/distortion/distortion.html]6moons.com - industry features: "Distortion &

[oatmeal769]

if you want a plain ZD I think youll need to go used

Why do you say that?

[Sherwood]

I'm not sure that Craig is still making them. Everything he does is in small, limited runs.

[oatmeal769]

Besides, where in the world would I find a used one? I don't think I've seen one ever...

[Hopstretch]

They come up for sale on HF reasonably regularly. The last one went for $1600-odd.

[Icarium]

I forget if the ZDT comes with tubes or not but at 2.5k or 2.6k or whatever with the ZD new at 2.2k with output tubes (Or is it more for the SE?)... ZDT is a no brainer for me. It's a flat out superior amp single ended to single ended even.

Then again I base my experience on the nautilus and the ZDT is supposed to be quite improved from the nautilus.

[oatmeal769]

I forget if the ZDT comes with tubes or not but at 2.5k or 2.6k or whatever with the ZD new at 2.2k with output tubes (Or is it more for the SE?)... ZDT is a no brainer for me. It's a flat out superior amp single ended to single ended even.

Then again I base my experience on the nautilus and the ZDT is supposed to be quite improved from the nautilus.

To my ears, the ZD is about the best I've heard so far across a broad spectrum for general listening. (There may be others that do certain things better) Do you think the ZDT 'sounds' better, or is it that it 'measures' better? I only care about the former.

The $300 difference isn't a big deal when we're already in the $2K range, but maybe it just comes down to whether one likes some transformer sound in the mix, or more of a pure tube sound?

[recstar24]

Slightly off topic, but I've always wanted to understand a bit more about this tube v. transistor argument.

I understand that there are lots of sonic preferences involved, but from a purely technical perspective, is it possible to design/produce a pure tube amp that can measure as well as a state of the art solid state job in terms of output power/harmonic distortion/damping factor/FR linearity/anything else you can throw at it?

I'm not trying to say those measurements necessarily 'mean' anything in the overall sound, I'd just like to know some of the 'science' behind the arguments. I have some dumb conception that I've picked up that somehow a good SS amp is more 'accurate' to the original source signal, and would like to know if there is actually any technical basis to that statement whatsoever, at least comparing best case scenario to best case scenario.

The only thing that I have read about a tube design with actual published specs and measurements that seems to even come close to solid state stuff is here:

Axiom Project

Doug I sent you a link to that a while back, I would love to hear your comments. Some of it I believe you already agreed with, specifically the idea that tubes should be operated as constant current, variable voltage devices. The axiom uses plate choke loading where you have used a CCS for my amp and some of yours, I think a choke however has some non-linearities towards the extremes of the frequency response. I wonder what your thoughts are on his claim about the use of diodes in the cathode circuit reducing distortion.

As for tubes vs. transistors the only applicable thing to this thread I can add is that when I asked Craig about it when I reviewed the original ZD, he felt that tubes captured the signal transfer characteristics that resembled music much better than transistors. He also said that if you were to compare the perfect output transformer to the perfect output coupling cap the transformer would be better due to lower source resistance, better drive and bandwidth and less loading of the tube. In the real world that is not ideal especially SE because SE transformers need big cores to allow DC without saturating but big cores means not as good coupling between the primary and secondary, and doing both is very hard and expensive. Good coupling caps with good dissipation factors are much easier and cheaper to build but some people's ears just tune better to one or the other. Again this is for SE pushpull is a different story.