[SteveM324]

The 500 mW into 50 ohms from the HI power output that was quoted from the Stereophile review was given to the reviewer by LTA's PR guy, Nicholas Tolson. That specification seems quite different from the specs on the LTA website of 3W @ 32ohms on the HI power output. The reviewer, Herb Reichert, said the 10e had zero punch, instrumental weight or get up and go energy driving the Susvara. Based on that description, I suspect that the 500mW @50 ohms high output maybe the correct spec and not the 3W@32 ohms. I'm just quoting the review, I have no experience with the 10e.

 

[jtnt]

Hey everybody. Nicholas from LTA here. Thought I'd clear up any confusion about the output on the Z10e.

Herb's review unit was sent to him before we changed the headphone output to match the speaker output. There is a manufacturer's comment in the back of the issue to that effect, but of course some won't see this. So, I will include our comment in its entirety below for sake of clarity.

Many thanks to the venerable Herb Reichert for his thoughtful column on our Z10e electrostatic headphone amp / integrated amp. We know it takes a lot of time to dive into such a versatile product, and we appreciate the effort Herb put in to so thoroughly explore the Z10e's capabilities.

Herb mentions that the dynamic headphone output fell a bit short of expectations with the hard-to-drive HiFiMan Susvara, and laments, "Why can't Linear Tube Audio give the headphone output the same power and gain it gives the speaker output?"

Since sending Herb this amp for review, we have heard the same from our customers. So, we reworked our original, conservative headphone outputs to be more powerful.

The “HI” output now puts out the same voltage and gain as the speaker outputs, about 3W into 32 Ohms. We are certain that this is ample power for the Susvara and other hard to drive headphones. The “LO” output provides 240mW to 32 Ohms.

If any of you ever have any questions about a piece of equipment, from LTA or anyone else, I encourage you to reach out directly to the manufacturer. We are always happy to answer questions and clear up any confusion that may be out there.

Thanks.

 

[SteveM324]

Hey everybody. Nicholas from LTA here. Thought I'd clear up any confusion about the output on the Z10e.

Herb's review unit was sent to him before we changed the headphone output to match the speaker output. There is a manufacturer's comment in the back of the issue to that effect, but of course some won't see this. So, I will include our comment in its entirety below for sake of clarity.



If any of you ever have any questions about a piece of equipment, from LTA or anyone else, I encourage you to reach out directly to the manufacturer. We are always happy to answer questions and clear up any confusion that may be out there.

Thanks.

Thanks for the clarification Nicholas!

 

[Jon L]

If any of you ever have any questions about a piece of equipment, from LTA or anyone else, I encourage you to reach out directly to the manufacturer. We are always happy to answer questions and clear up any confusion that may be out there.

Thanks.

Hello. Can you confirm if LTA Z10e is adding transformers to Z10's output to step up the voltage for electrostat drive? Thank you.

 

[headinclouds]

There does not seem to be much info available that describe the difference between LTA Z10 vs. Z10e. Both are rated at 12 watts into 8 Ohm speakers, so I presume the basic amplification circuit is same/similar, so how is the electrostat drive derived? It's difficult to think LTA would simply add Stax SRD-7 style transformer to LTA Z10, but..?

They are tube amplifiers and before the ZOTL matching to the speaker load there exists outputs at hundreds of volts already. I doubt any transformers are involved. But it is not for me to second guess LTA

 

[jtnt]

Hello. Can you confirm if LTA Z10e is adding transformers to Z10's output to step up the voltage for electrostat drive? Thank you.

@headinclouds is correct, there are no transformers. The electrostatic signal comes straight off the tube, and due to ZOTL's unique topology, the tubes run natively at 750V, for a 1500V peak to peak (each channel has two tubes, one is for the bottom half of the signal and one for the top half, so the full voltage swing is both added together). The ectrostatic headphone output is live all the time, because we didn't want to degrade the audio signal with a switch.

 

[headinclouds]

Thank you Nicholas for those interesting facts.

 

[Jon L]

@headinclouds is correct, there are no transformers. The electrostatic signal comes straight off the tube, and due to ZOTL's unique topology, the tubes run natively at 750V, for a 1500V peak to peak (each channel has two tubes, one is for the bottom half of the signal and one for the top half, so the full voltage swing is both added together). The ectrostatic headphone output is live all the time, because we didn't want to degrade the audio signal with a switch.

That's good to hear. Thanks.

 

[thomaskong78]

@headinclouds is correct, there are no transformers. The electrostatic signal comes straight off the tube, and due to ZOTL's unique topology, the tubes run natively at 750V, for a 1500V peak to peak (each channel has two tubes, one is for the bottom half of the signal and one for the top half, so the full voltage swing is both added together). The ectrostatic headphone output is live all the time, because we didn't want to degrade the audio signal with a switch.

Nice work!

I am intrigued with your amp since I have 009s.

 

[davesa]

Just another thought - I have my amp being fed by my Yggdrasil - I have both XLR and RCA cables going to the amp and I can switch between them ( since there are 3 inputs ) - most of the time I have been listening on the XLR input, even though it gets converted to single ended. I switch to the RCA if I am driving more sensitive headphones.

I use the Monoprice Premier series cables, which sound really good to me, even though they are pretty inexpensive. I just ordered and tried their new Monolith XLR cables. The Monoliths are very well made and look great, but seemed darker to me, and I liked the brighter sound of the premier so I will be returning the Monoliths.

 

[complin]

@headinclouds is correct, there are no transformers. The electrostatic signal comes straight off the tube, and due to ZOTL's unique topology, the tubes run natively at 750V, for a 1500V peak to peak (each channel has two tubes, one is for the bottom half of the signal and one for the top half, so the full voltage swing is both added together). The ectrostatic headphone output is live all the time, because we didn't want to degrade the audio signal with a switch.

Sill somewhat confused by your reply as we are not asking if the amplifier uses output transformers as those of us who have used David Berning's stereo amplifiers for years are aware they do not use transformers like a traditional valve amplifier. However; from my experience they do still use small transformers for the high frequency carrier on which the audio signal piggy backs so that the traditional large output transformers can be dispensed with hence ZOTL. This is all explained on David's web site.

The assumption is that this product is based on your speaker amplifier and what we are trying to understand is how you have implemented the electrostatic driving function.
Many manufacturers do this by implementing in their amplifier functionality like the SRD-7 energizer driven by the speaker output. Basically it piggy-backs on the existing speaker amplifier, where it takes the current from the speaker amplifier and converts it to the necessary high voltage power (via 2 small transformers, one for each channel) for driving the Stax Electrostatic headphones. It provides both the drive for the signal and the 580V bias voltage to charge the stators

Perhaps you could clarify further?
Perhaps a simple circuit diagram would help?

Stax Energizer

 

[jtnt]

@complin My response to @headinclouds and @Jon L about transformers was specific to the question about whether we use step-up transformers to achieve the necessary voltages for the electrostatic output, not about the overall use of output transformers. Excuse my use of the word "transformers" without the "step-up" placed before it that would have possibly provided the necessary specificity to avoid this confusion.

As detailed in my answer, the voltages we run natively in the tubes provide us all we need for the 580V electrostatic output, which comes straight off the tubes - the same tubes that run the speaker output and everything else - without needing any step-up transformers or other functionality.

 

[saidentary]

Hello Nicholas,

Is there any difference between the circuits for the dynamic headphone outputs for the Z10 integrated amplifer and the dynamic headphone outputs for the Z10E? Based on carefully reading the specifications (which were recently revised for the dynamic outputs of the Z10E, as you note above), it looks (to me at least) like they're identical, and that the dynamic headphone outputs for both units should sound identical. Is that correct or not?

 

[complin]

@complin My response to @headinclouds and @Jon L about transformers was specific to the question about whether we use step-up transformers to achieve the necessary voltages for the electrostatic output, not about the overall use of output transformers. Excuse my use of the word "transformers" without the "step-up" placed before it that would have possibly provided the necessary specificity to avoid this confusion.

As detailed in my answer, the voltages we run natively in the tubes provide us all we need for the 580V electrostatic output, which comes straight off the tubes - the same tubes that run the speaker output and everything else - without needing any step-up transformers or other functionality.

Thankyou @jtnt
You also mentioned in your original post that "the tubes run natively at 750V, for a 1500V peak to peak each channel"
Are these voltages you have quoted the operating voltages of the tubes?
If that is the case could you say more about what the actual output of the electrostatic headphone output provides, that is the specification in electrical terms.
For example what the overall gain in db, output voltage etc.....
i.e. 400V power, 800vppss

 

[jtnt]

Thankyou @jtnt
You also mentioned in your original post that "the tubes run natively at 750V, for a 1500V peak to peak each channel"
Are these voltages you have quoted the operating voltages of the tubes?
If that is the case could you say more about what the actual output of the electrostatic headphone output provides, that is the specification in electrical terms.
For example what the overall gain in db, output voltage etc.....
i.e. 400V power, 800vppss

Running the tubes at those voltages (and 1/3 the current) is part of the unique nature of the ZOTL circuit.

I'll have to consult more technical minds than me if you want deeper info, but the electrostatic output is the standard STAX 580v interface. https://staxaudio.com/technology