[MojoAudio]

  Hi, everyone.  New to this forum and a new owner of a microZOTL2 + LPS amplifier (serial number 0153).  The fact that Berning is interested in a ZOTL-based electrostatic headphone amplifier fascinates and baffles me. The genius of the ZOTL design is the  active impedance dropping circuity that Dave has developed to power low impedance dynamic headphones (16 to 600 ohms) from the high impedance output tube plates without using audio frequency transformers.  But electrostatic headphones have very high impedance, roughly 100,000 ohms or higher.  This is an impedance level that tubes can easily drive without help from an output transformer or from a ZOTL section. Thus, there is no need for a ZOTL output section; the tube plates can be directly coupled (by capacitor) to the electrostatic stators.  This has been recognized for decades, and dozens of amplifiers from Stax and others (Gilmore, Woo) have gone down this OTL path.  What I want to know is what Dave could possibly devise that is new and worth marketing along this line.

 
I can't speak for everyone else, but my reason for me wanting a ZOTL10 electrostatic amp would be that I could have one amp in my bedroom that would be a ZOTL10 to play through a pair of speakers, as well as a dynamic headphones, as well as electrostatic headphones. Can any of those other electrostatic amps drive dynamic headphones and speakers too?

 

[Egghead]

   
I can't speak for everyone else, but my reason for me wanting a ZOTL10 electrostatic amp would be that I could have one amp in my bedroom that would be a ZOTL10 to play through a pair of speakers, as well as a dynamic headphones, as well as electrostatic headphones. Can any of those other electrostatic amps drive dynamic headphones and speakers too?

I concede none can, but the size of the market for such flexibility in one box must be minuscule.  If I have already invested in high quality electrostatic headphones worthy of a super quality amplifier (one to thousands of dollars), then I already own a quality electrostatic amplifier. If it is solid state it is already OTL, and if it is tube it is likely to be OTL. So what I need for my electrostatic amplifier is an add-on step-down device that drives dynamic headphones and small speakers via the headphone output jack.  This is just the opposite of the step up transformers Stax markets for electrostatic headphones driven from standard amplifier speaker terminals.  But the approach is problematic for a ZOTL add-on, since a wide variety of electostatic headphone amps must be accommodated with the potential for gain and feedback stability issues when driving a ZOTL circuit.  If one wanted flexiblity and is willing to put up with two boxes, why wouldn't one buy a good, standard integrated amp (maybe even solid state!) and add an electrostatic step up transformer? Or better, keep the electrostatic headphone amp and by a microZOTL2 or ZOTL10 modified with an added headphone jack? 

 

[MojoAudio]

  I concede none can, but the size of the market for such flexibility in one box must be minuscule.  If I have already invested in high quality electrostatic headphones worthy of a super quality amplifier (one to thousands of dollars), then I already own a quality electrostatic amplifier. If it is solid state it is already OTL, and if it is tube it is likely to be OTL. So what I need for my electrostatic amplifier is an add-on step-down device that drives dynamic headphones and small speakers via the headphone output jack.  This is just the opposite of the step up transformers Stax markets for electrostatic headphones driven from standard amplifier speaker terminals.  But the approach is problematic for a ZOTL add-on, since a wide variety of electostatic headphone amps must be accommodated with the potential for gain and feedback stability issues when driving a ZOTL circuit.  If one wanted flexiblity and is willing to put up with two boxes, why wouldn't one buy a good, standard integrated amp (maybe even solid state!) and add an electrostatic step up transformer? Or better, keep the electrostatic headphone amp and by a microZOTL2 or ZOTL10 modified with an added headphone jack? 

 
This would not be some compromise as you are implying. No step up or down - the topology of the ZOTL10 is nearly identical to a direct-drive electrostatic amp. I'm an EE and I would simply have a switching board that would allow me to direct drive the high impedance electrostatic headphones through a constant current source with a bias current, and switch to the ZOTL circuit for everything else.
 
I own/love a highly modified Stax T1 amp and Omega II SR-007 Mk1 headphones. We have a few high-level DIYers here in ABQ and we literally meet a few times a month to play our upgraded or custom Stax amps for each other (we're actually meeting tomorrow). All I can say is the concept of an all tube direct-drive electrostatic amp with EL84 output tubes intrigues me.
 
Since I already wanted a ZOTL10 for my bedroom, I'm tickled that LTA is considering this project. No promises from LTA, but I'm crossing my fingers, and I want an amp from the first production run

 

[zachawry]

I read on the LG thread that you were getting the Glass. Did you get around to it? managed to compare it to the MZ2?

Was going to get the Glass, but didn't relish the thought of waiting 7-8 months for it. Got the MZ2 instead. 

 

[Wildcatsare1]

Was going to get the Glass, but didn't relish the thought of waiting 7-8 months for it. Got the MZ2 instead. 

I was in line for an LAu, but have decided to go with the ZOTL (review pending). Listened to the LAu at the Nashville Meet and slightly preferred the ZOTL, it actually had superior clarity. Plus it's much less expensive and the acquisition process is superior.

 

[sheldaze]

I was in line for an LAu, but have decided to go with the ZOTL (review pending). Listened to the LAu at the Nashville Meet and slightly preferred the ZOTL, it actually had superior clarity. Plus it's much less expensive and the acquisition process is superior.

Looking forward to your review!
Also, hope things are all settled for you. I'll definitely have to make the next SouthEast meet.

 

[Wildcatsare1]

Looking forward to your review!
Also, hope things are all settled for you. I'll definitely have to make the next SouthEast meet.

I look forward to finally meeting you Sheldon! Just need to get my Audio Room/Office set up again. Hated to miss Canlanta, but it was literally on our moving day.

Does anybody know if there is a Head Fi Group in the Lexington, Louisville, Cinncinati area?

 

[Egghead]

   
This would not be some compromise as you are implying. No step up or down - the topology of the ZOTL10 is nearly identical to a direct-drive electrostatic amp. I'm an EE and I would simply have a switching board that would allow me to direct drive the high impedance electrostatic headphones through a constant current source with a bias current, and switch to the ZOTL circuit for everything else.
 
I own/love a highly modified Stax T1 amp and Omega II SR-007 Mk1 headphones. We have a few high-level DIYers here in ABQ and we literally meet a few times a month to play our upgraded or custom Stax amps for each other (we're actually meeting tomorrow). All I can say is the concept of an all tube direct-drive electrostatic amp with EL84 output tubes intrigues me.
 
Since I already wanted a ZOTL10 for my bedroom, I'm tickled that LTA is considering this project. No promises from LTA, but I'm crossing my fingers, and I want an amp from the first production run

If you want a taste of EL84 sound, the Kingsound M-20 exists today and is an EL84 output electrostatic amp.  It runs all triode, with a similar input amp and phase splitter design as the microZOTL but not in constant current on the output tubes.  This last gives it a softer, tube-like sound which I anticipate will be the sound of a ZOTL 10 modified as you suggest but without constant current.  I use the Kingsound with my L-700s every day.  It works well, but the sound is definitely not ZOTL sound.

 

[MojoAudio]

  If you want a taste of EL84 sound, the Kingsound M-20 exists today and is an EL84 output electrostatic amp.  It runs all triode, with a similar input amp and phase splitter design as the microZOTL but not in constant current on the output tubes.  This last gives it a softer, tube-like sound which I anticipate will be the sound of a ZOTL 10 modified as you suggest but without constant current.  I use the Kingsound with my L-700s every day.  It works well, but the sound is definitely not ZOTL sound.

 
I'm not looking for a "taste" of anything. I likely have the parts in my spare parts bins to build an EL-84 electrostatic amp and I could probably build one on a piece of wood in about a day.
 
I have no doubt the Kingsound amp is high-value product. The problem is that both my T1 and the Kingsound are built from modest quality parts (as all components in their price range are) and they have little room inside their chassis to add proper parts. Of course ZOTL chassis are much bigger
 
I have two local high-level DIYers coming over today to audition and discuss the various modifications we've made to our personal electrostatic headphone amps in the past couple of weeks. Between the three of us we own a pair of Stax Lambda Pros, Lambda Nova Signatures, Omega 007 Mk1, and Mk2. 
 
We are literally going through all the old Stax and Gilmore schematics we can get our hands on and re-engineering them with better power supplies and better component part choices. I have no doubt that in the next year or three I'll be building myself a custom electrostatic amp that will weigh around 50 pounds and cost me over $3K in parts. Seriously. Good iron is heavy and expensive.
 
The BIG advantage of this still theoretical ZOTL10 electrostatic amp is that no other electrostatic amp can drive both electrostatic headphones and dynamic speakers.  So even after I've built my dream electrostatic headphone amp I'm sure I would still want to have such a versatile little amplifier in my bedroom.
 
As interesting as the topic of LTA making an electrostatic amp is, this is an mZ2 thread, and we've gotten pretty far off topic discussing theoretical future products from LTA.

 

[Jozurr]

   
Where, in what thread, on what specific posts, are you reading this?

 
Went back and searched, I read vibrant and not dynamic.

 
Was going to get the Glass, but didn't relish the thought of waiting 7-8 months for it. Got the MZ2 instead. 

 
Did you hear the glass? If yes how did you like it compared to your MZ2?
 

I was in line for an LAu, but have decided to go with the ZOTL (review pending). Listened to the LAu at the Nashville Meet and slightly preferred the ZOTL, it actually had superior clarity. Plus it's much less expensive and the acquisition process is superior.

 
Other than clarity, what else did you like on the Zotl vs the LAu?
 
I've just acquired the Liquid Glass, which is an amzing amp in it's own right, but my curiosity is still making me consider the MZ2.

 

[Wildcatsare1]

Went back and searched, I read vibrant and not dynamic.

Did you hear the glass? If yes how did you like it compared to your MZ2?


Other than clarity, what else did you like on the Zotl vs the LAu?

I've just acquired the Liquid Glass, which is an amzing amp in it's own right, but my curiosity is still making me consider the MZ2.

Not so much superior, but more of an equal to the LAu. Though, show conditions and the ZOTL was in my personal system to review. I love the Cavali house sound, have the LC, but equality at half the price makes me tilt to the MicrZOTL 2.

 

[MojoAudio]

Not so much superior, but more of an equal to the LAu. Though, show conditions and the ZOTL was in my personal system to review. I love the Cavali house sound, have the LC, but equality at half the price makes me tilt to the MicrZOTL 2.

 
I think the LG is a unique concept with all the various tubes you can use. But the same electronics schema that allows for all that versatility will invariably limit performance with all the extra switching and physical proximity between parts. Any engineer worth his salt will tell you "less is more."
 
Everyone has experienced this with one product or another.
 
Personally I own/love my Honda Element that converts from an SUV to a passenger mini-van to a cargo van and to a camper. It does all those things but none of them particularly well. Of course I love it because I needed versatility over ultimate performance. I think many of you will find you'll have a similar opinion of the LC.
 
Back to the mZ2, what PSU did you use with your mZ2 when you compared it to the LC Wildcatsare1?
 
The reason I ask is that is if you compared the LG with the original ZOTL/SMPS and it was close to the LG, then the mZ2 with the new ZOTL LPS could be significantly better than the LC for a fraction of the price.
 
Now factor in that the LG has to have either output caps or transformers that inevitably distort time/tune/phase and limit bandwidth and the mZ2 doesn't.
 
For a person with deep pockets that was looking to spend >$2,500 on a dynamic headphone amp, I would seriously recommend considering an mZ2 upgraded with an über PSU that sells for >$1K, such as a Paul Hynes or Uptown Audio. And if you had really deep pockets there are even better power supplies out there for >$1,500

 

[MojoAudio]

Did I ever mention that if any of you wanted to upgrade your mZ2, for about $350-$500 in parts and an afternoon with a soldering gun, you could take an mZ2 to a whole new level of performance?

 

[Greggo]

For whatever it is worth, I will share my own recent struggles in planning my ongoing headphone journey...
 
I have a Cavalli Liquid Carbon on the way and I am expecting it will be my last amp for a while but I could easily see myself upgrading to a used Crimson or Glass. I have a Nighthawk and getting ready to add an HD800S to the equation.
 
I will wait another year or two and see what Hifiman, Audeze, and Mr Speakers come up with, but the one thing I heard recently that really blew my mind was @comzee 's rig at the Minneapolis meet a couple weeks ago. I would be really tracking the anticipation of the Mr Speaker's electrostat but the idea of needing a Cavalli Lightning or something similar means it would be just too much of an investment and too narrow of a focus to have any rationale role in my plans. I would either go "all in" electrostatic or stay away and remain focused on dynamics and planars. I know I could never do the former because it is not a sound that I would truly love across all genres all the time as my only option, but it is something I would truly treasure as one of a few options depending on my mood
 
The idea that I might be able to buy an amp that would stay in the 2-3k range (???) instead of 4-5k range, and allow me to do justice to an HD800S and any high end electrostat would be a complete game changer and I  would be all over it, especially if a really high end electrostatic headphone option in the 2.5k range became an option at some point down the road.

 

[Hifi01170]

  Did I ever mention that if any of you wanted to upgrade your mZ2, for about $350-$500 in parts and an afternoon with a soldering gun, you could take an mZ2 to a whole new level of performance?
 

 
can you please share how??