There are two ZDs listed for sale that are available right now!

New & Used Stuff

I inquired if both were from the 2009 run and Craig confirmed that they are. I kinda want a ZD now but if I actually go for one (not really sure yet), I think I'll be going for a new one with the impedance switch...

once you go BA you never go back:p I love the ZD but the BA is just sooo much better. I know its a grand more but that is why god blessed you with 2 kidneys one for you and one for ebay

once you go BA you never go back:p I love the ZD but the BA is just sooo much better. I know its a grand more but that is why god blessed you with 2 kidneys one for you and one for ebay

Well looking at your last few purchases *galabier* cough, I guess you have no kidneys left.

I'm using a mr coffee filter at the moment

You should try something organic. Or recycled. Or both.

I find cardboard on an end grain works

I'm going to go ahead and give you 24hrs to ponder that remark.

My bad about being a sarcastic asshat...

My bad about being a sarcastic asshat...

Well, this is a step in the right direction. Welcome back.

My bad about being a sarcastic asshat...

Asshat is rather generous. We reserve the term jagbag for situations like this.

Some quick questions for my technically-minded friends. So how would one likely implement a high/low impedance control on an OTL amp like this? And how much of a performance advantage is it actually likely to afford with low-impedance headphones over the stock configuration? At the NY meet, I thought the stock Zana sounded very good with HP-1s, though I know the combo wouldn't necessarily be considered a great match on paper.

Ah theng kyew.

Typically (and I don't know the Zana topology specifically) the only thing that could be done easily would be to run each output through different sized coupling caps. The high-ohm output requires a smaller cap to achieve uniform frequency response so typically builders/designers use high-quality film caps here, for the low-ohm output the cap size can need to be 10x as large (uF wise) and therefore it's simply not practical or affordable to use a film cap so what is often done is to use a film/electrolytic couple in parallel. Could be that the low-ohm switch just adds the electrolytic in parallel with the cap used on the high-ohm output. Hard telling not knowing.

In a more complex world it might be possible to alter a portion of the circuit to allow the tubes to more efficiently drive the low-impedance load but doing so via a switch wouldn't sit well with me.

Some quick questions for my technically-minded friends. So how would one likely implement a high/low impedance control on an OTL amp like this? And how much of a performance advantage is it actually likely to afford with low-impedance headphones over the stock configuration? At the NY meet, I thought the stock Zana sounded very good with HP-1s, though I know the combo wouldn't necessarily be considered a great match on paper.

Ah theng kyew.

I asked Craig about it, basically I asked if whether the switch somehow increases the feedback a bit so that it brings the output resistance lower, and he said "That's about it". Last time I checked, the 6C33C-B is biased for a plate resistance of about 90 ohms, and with a little bit of feedback, he brings it to 12 ohms output in stock configuration. So I would imagine the easiest way to implement a lower impedance through a switch would be just having that switch either have a different bias setting for the 6C33CB so the plate resistance is a bit lower, either increasing the feedback level, or maybe a combo of both.

Multiple input switch. I like that. Wish more manufacturers did that.

Multiple input switch. I like that. Wish more manufacturers did that.

Lots do on their full sized gear, which in particular are you wishing did?

My WA6 has an impedance switch - not sure how it works on that amp (whether a multi-tap transformer, or some other trick).

The Woo6 has output transformers so you are switching between multiple taps.